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A GNU Manual
(b) The FSF's Back-Cover Text is:
You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development.
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This manual documents how to use the GNU compilers, as well as their features and incompatibilities, and how to report bugs. It corresponds to the compilers version 4.7.2. The internals of the GNU compilers, including how to port them to new targets and some information about how to write front ends for new languages, are documented in a separate manual. See Introduction.
GCC stands for “GNU Compiler Collection”. GCC is an integrated distribution of compilers for several major programming languages. These languages currently include C, C++, Objective-C, Objective-C++, Java, Fortran, Ada, and Go.
The abbreviation GCC has multiple meanings in common use. The current official meaning is “GNU Compiler Collection”, which refers generically to the complete suite of tools. The name historically stood for “GNU C Compiler”, and this usage is still common when the emphasis is on compiling C programs. Finally, the name is also used when speaking of the language-independent component of GCC: code shared among the compilers for all supported languages.
The language-independent component of GCC includes the majority of the optimizers, as well as the “back ends” that generate machine code for various processors.
The part of a compiler that is specific to a particular language is called the “front end”. In addition to the front ends that are integrated components of GCC, there are several other front ends that are maintained separately. These support languages such as Pascal, Mercury, and COBOL. To use these, they must be built together with GCC proper.
Most of the compilers for languages other than C have their own names. The C++ compiler is G++, the Ada compiler is GNAT, and so on. When we talk about compiling one of those languages, we might refer to that compiler by its own name, or as GCC. Either is correct.
Historically, compilers for many languages, including C++ and Fortran, have been implemented as “preprocessors” which emit another high level language such as C. None of the compilers included in GCC are implemented this way; they all generate machine code directly. This sort of preprocessor should not be confused with the C preprocessor, which is an integral feature of the C, C++, Objective-C and Objective-C++ languages.
For each language compiled by GCC for which there is a standard, GCC attempts to follow one or more versions of that standard, possibly with some exceptions, and possibly with some extensions.
GCC supports three versions of the C standard, although support for the most recent version is not yet complete.
The original ANSI C standard (X3.159-1989) was ratified in 1989 and published in 1990. This standard was ratified as an ISO standard (ISO/IEC 9899:1990) later in 1990. There were no technical differences between these publications, although the sections of the ANSI standard were renumbered and became clauses in the ISO standard. This standard, in both its forms, is commonly known as C89, or occasionally as C90, from the dates of ratification. The ANSI standard, but not the ISO standard, also came with a Rationale document. To select this standard in GCC, use one of the options -ansi, -std=c90 or -std=iso9899:1990; to obtain all the diagnostics required by the standard, you should also specify -pedantic (or -pedantic-errors if you want them to be errors rather than warnings). See Options Controlling C Dialect.
Errors in the 1990 ISO C standard were corrected in two Technical Corrigenda published in 1994 and 1996. GCC does not support the uncorrected version.
An amendment to the 1990 standard was published in 1995. This
amendment added digraphs and __STDC_VERSION__ to the language,
but otherwise concerned the library. This amendment is commonly known
as AMD1; the amended standard is sometimes known as C94 or
C95. To select this standard in GCC, use the option
-std=iso9899:199409 (with, as for other standard versions,
-pedantic to receive all required diagnostics).
A new edition of the ISO C standard was published in 1999 as ISO/IEC 9899:1999, and is commonly known as C99. GCC has incomplete support for this standard version; see http://gcc.gnu.org/gcc-4.7/c99status.html for details. To select this standard, use -std=c99 or -std=iso9899:1999. (While in development, drafts of this standard version were referred to as C9X.)
Errors in the 1999 ISO C standard were corrected in three Technical Corrigenda published in 2001, 2004 and 2007. GCC does not support the uncorrected version.
A fourth version of the C standard, known as C11, was published in 2011 as ISO/IEC 9899:2011. GCC has limited incomplete support for parts of this standard, enabled with -std=c11 or -std=iso9899:2011. (While in development, drafts of this standard version were referred to as C1X.)
By default, GCC provides some extensions to the C language that on rare occasions conflict with the C standard. See Extensions to the C Language Family. Use of the -std options listed above will disable these extensions where they conflict with the C standard version selected. You may also select an extended version of the C language explicitly with -std=gnu90 (for C90 with GNU extensions), -std=gnu99 (for C99 with GNU extensions) or -std=gnu11 (for C11 with GNU extensions). The default, if no C language dialect options are given, is -std=gnu90; this will change to -std=gnu99 or -std=gnu11 in some future release when the C99 or C11 support is complete. Some features that are part of the C99 standard are accepted as extensions in C90 mode, and some features that are part of the C11 standard are accepted as extensions in C90 and C99 modes.
The ISO C standard defines (in clause 4) two classes of conforming
implementation. A conforming hosted implementation supports the
whole standard including all the library facilities; a conforming
freestanding implementation is only required to provide certain
library facilities: those in <float.h>, <limits.h>,
<stdarg.h>, and <stddef.h>; since AMD1, also those in
<iso646.h>; since C99, also those in <stdbool.h> and
<stdint.h>; and since C11, also those in <stdalign.h>
and <stdnoreturn.h>. In addition, complex types, added in C99, are not
required for freestanding implementations. The standard also defines
two environments for programs, a freestanding environment,
required of all implementations and which may not have library
facilities beyond those required of freestanding implementations,
where the handling of program startup and termination are
implementation-defined, and a hosted environment, which is not
required, in which all the library facilities are provided and startup
is through a function int main (void) or int main (int,
char *[]). An OS kernel would be a freestanding environment; a
program using the facilities of an operating system would normally be
in a hosted implementation.
GCC aims towards being usable as a conforming freestanding
implementation, or as the compiler for a conforming hosted
implementation. By default, it will act as the compiler for a hosted
implementation, defining __STDC_HOSTED__ as 1 and
presuming that when the names of ISO C functions are used, they have
the semantics defined in the standard. To make it act as a conforming
freestanding implementation for a freestanding environment, use the
option -ffreestanding; it will then define
__STDC_HOSTED__ to 0 and not make assumptions about the
meanings of function names from the standard library, with exceptions
noted below. To build an OS kernel, you may well still need to make
your own arrangements for linking and startup.
See Options Controlling C Dialect.
GCC does not provide the library facilities required only of hosted implementations, nor yet all the facilities required by C99 of freestanding implementations; to use the facilities of a hosted environment, you will need to find them elsewhere (for example, in the GNU C library). See Standard Libraries.
Most of the compiler support routines used by GCC are present in
libgcc, but there are a few exceptions. GCC requires the
freestanding environment provide memcpy, memmove,
memset and memcmp.
Finally, if __builtin_trap is used, and the target does
not implement the trap pattern, then GCC will emit a call
to abort.
For references to Technical Corrigenda, Rationale documents and information concerning the history of C that is available online, see http://gcc.gnu.org/readings.html
GCC supports the original ISO C++ standard (1998) and contains experimental support for the second ISO C++ standard (2011).
The original ISO C++ standard was published as the ISO standard (ISO/IEC
14882:1998) and amended by a Technical Corrigenda published in 2003
(ISO/IEC 14882:2003). These standards are referred to as C++98 and
C++03, respectively. GCC implements the majority of C++98 (export
is a notable exception) and most of the changes in C++03. To select
this standard in GCC, use one of the options -ansi,
-std=c++98, or -std=c++03; to obtain all the diagnostics
required by the standard, you should also specify -pedantic (or
-pedantic-errors if you want them to be errors rather than
warnings).
A revised ISO C++ standard was published in 2011 as ISO/IEC 14882:2011, and is referred to as C++11; before its publication it was commonly referred to as C++0x. C++11 contains several changes to the C++ language, most of which have been implemented in an experimental C++11 mode in GCC. For information regarding the C++11 features available in the experimental C++11 mode, see http://gcc.gnu.org/projects/cxx0x.html. To select this standard in GCC, use the option -std=c++11; to obtain all the diagnostics required by the standard, you should also specify -pedantic (or -pedantic-errors if you want them to be errors rather than warnings).
More information about the C++ standards is available on the ISO C++ committee's web site at http://www.open-std.org/jtc1/sc22/wg21/.
By default, GCC provides some extensions to the C++ language; See Options Controlling C++ Dialect. Use of the -std option listed above will disable these extensions. You may also select an extended version of the C++ language explicitly with -std=gnu++98 (for C++98 with GNU extensions) or -std=gnu++11 (for C++11 with GNU extensions). The default, if no C++ language dialect options are given, is -std=gnu++98.
GCC supports “traditional” Objective-C (also known as “Objective-C 1.0”) and contains support for the Objective-C exception and synchronization syntax. It has also support for a number of “Objective-C 2.0” language extensions, including properties, fast enumeration (only for Objective-C), method attributes and the @optional and @required keywords in protocols. GCC supports Objective-C++ and features available in Objective-C are also available in Objective-C++.
GCC by default uses the GNU Objective-C runtime library, which is part of GCC and is not the same as the Apple/NeXT Objective-C runtime library used on Apple systems. There are a number of differences documented in this manual. The options -fgnu-runtime and -fnext-runtime allow you to switch between producing output that works with the GNU Objective-C runtime library and output that works with the Apple/NeXT Objective-C runtime library.
There is no formal written standard for Objective-C or Objective-C++. The authoritative manual on traditional Objective-C (1.0) is “Object-Oriented Programming and the Objective-C Language”, available at a number of web sites:
The Objective-C exception and synchronization syntax (that is, the keywords @try, @throw, @catch, @finally and @synchronized) is supported by GCC and is enabled with the option -fobjc-exceptions. The syntax is briefly documented in this manual and in the Objective-C 2.0 manuals from Apple.
The Objective-C 2.0 language extensions and features are automatically enabled; they include properties (via the @property, @synthesize and @dynamic keywords), fast enumeration (not available in Objective-C++), attributes for methods (such as deprecated, noreturn, sentinel, format), the unused attribute for method arguments, the @package keyword for instance variables and the @optional and @required keywords in protocols. You can disable all these Objective-C 2.0 language extensions with the option -fobjc-std=objc1, which causes the compiler to recognize the same Objective-C language syntax recognized by GCC 4.0, and to produce an error if one of the new features is used.
GCC has currently no support for non-fragile instance variables.
The authoritative manual on Objective-C 2.0 is available from Apple:
For more information concerning the history of Objective-C that is available online, see http://gcc.gnu.org/readings.html
The Go language continues to evolve as of this writing; see the current language specifications. At present there are no specific versions of Go, and there is no way to describe the language supported by GCC in terms of a specific version. In general GCC tracks the evolving specification closely, and any given release will support the language as of the date that the release was frozen.
See GNAT Reference Manual, for information on standard conformance and compatibility of the Ada compiler.
See Standards, for details of standards supported by GNU Fortran.
See Compatibility with the Java Platform, for details of compatibility between gcj and the Java Platform.
When you invoke GCC, it normally does preprocessing, compilation, assembly and linking. The “overall options” allow you to stop this process at an intermediate stage. For example, the -c option says not to run the linker. Then the output consists of object files output by the assembler.
Other options are passed on to one stage of processing. Some options control the preprocessor and others the compiler itself. Yet other options control the assembler and linker; most of these are not documented here, since you rarely need to use any of them.
Most of the command-line options that you can use with GCC are useful for C programs; when an option is only useful with another language (usually C++), the explanation says so explicitly. If the description for a particular option does not mention a source language, you can use that option with all supported languages.
See Compiling C++ Programs, for a summary of special options for compiling C++ programs.
The gcc program accepts options and file names as operands. Many options have multi-letter names; therefore multiple single-letter options may not be grouped: -dv is very different from ‘-d -v’.
You can mix options and other arguments. For the most part, the order you use doesn't matter. Order does matter when you use several options of the same kind; for example, if you specify -L more than once, the directories are searched in the order specified. Also, the placement of the -l option is significant.
Many options have long names starting with ‘-f’ or with ‘-W’—for example, -fmove-loop-invariants, -Wformat and so on. Most of these have both positive and negative forms; the negative form of -ffoo would be -fno-foo. This manual documents only one of these two forms, whichever one is not the default.
See Option Index, for an index to GCC's options.
Here is a summary of all the options, grouped by type. Explanations are in the following sections.
-c -S -E -o file -no-canonical-prefixes
-pipe -pass-exit-codes
-x language -v -### --help[=class[,...]] --target-help
--version -wrapper @file -fplugin=file -fplugin-arg-name=arg
-fdump-ada-spec[-slim] -fdump-go-spec=file
-ansi -std=standard -fgnu89-inline
-aux-info filename -fallow-parameterless-variadic-functions
-fno-asm -fno-builtin -fno-builtin-function
-fhosted -ffreestanding -fopenmp -fms-extensions -fplan9-extensions
-trigraphs -no-integrated-cpp -traditional -traditional-cpp
-fallow-single-precision -fcond-mismatch -flax-vector-conversions
-fsigned-bitfields -fsigned-char
-funsigned-bitfields -funsigned-char
-fabi-version=n -fno-access-control -fcheck-new
-fconserve-space -fconstexpr-depth=n -ffriend-injection
-fno-elide-constructors
-fno-enforce-eh-specs
-ffor-scope -fno-for-scope -fno-gnu-keywords
-fno-implicit-templates
-fno-implicit-inline-templates
-fno-implement-inlines -fms-extensions
-fno-nonansi-builtins -fnothrow-opt -fno-operator-names
-fno-optional-diags -fpermissive
-fno-pretty-templates
-frepo -fno-rtti -fstats -ftemplate-depth=n
-fno-threadsafe-statics -fuse-cxa-atexit -fno-weak -nostdinc++
-fno-default-inline -fvisibility-inlines-hidden
-fvisibility-ms-compat
-Wabi -Wconversion-null -Wctor-dtor-privacy
-Wdelete-non-virtual-dtor -Wnarrowing -Wnoexcept
-Wnon-virtual-dtor -Wreorder
-Weffc++ -Wstrict-null-sentinel
-Wno-non-template-friend -Wold-style-cast
-Woverloaded-virtual -Wno-pmf-conversions
-Wsign-promo
-fconstant-string-class=class-name
-fgnu-runtime -fnext-runtime
-fno-nil-receivers
-fobjc-abi-version=n
-fobjc-call-cxx-cdtors
-fobjc-direct-dispatch
-fobjc-exceptions
-fobjc-gc
-fobjc-nilcheck
-fobjc-std=objc1
-freplace-objc-classes
-fzero-link
-gen-decls
-Wassign-intercept
-Wno-protocol -Wselector
-Wstrict-selector-match
-Wundeclared-selector
-fmessage-length=n
-fdiagnostics-show-location=[once|every-line]
-fno-diagnostics-show-option
-fsyntax-only -fmax-errors=n -pedantic
-pedantic-errors
-w -Wextra -Wall -Waddress -Waggregate-return -Warray-bounds
-Wno-attributes -Wno-builtin-macro-redefined
-Wc++-compat -Wc++11-compat -Wcast-align -Wcast-qual
-Wchar-subscripts -Wclobbered -Wcomment
-Wconversion -Wcoverage-mismatch -Wno-cpp -Wno-deprecated
-Wno-deprecated-declarations -Wdisabled-optimization
-Wno-div-by-zero -Wdouble-promotion -Wempty-body -Wenum-compare
-Wno-endif-labels -Werror -Werror=*
-Wfatal-errors -Wfloat-equal -Wformat -Wformat=2
-Wno-format-contains-nul -Wno-format-extra-args -Wformat-nonliteral
-Wformat-security -Wformat-y2k
-Wframe-larger-than=len -Wno-free-nonheap-object -Wjump-misses-init
-Wignored-qualifiers
-Wimplicit -Wimplicit-function-declaration -Wimplicit-int
-Winit-self -Winline -Wmaybe-uninitialized
-Wno-int-to-pointer-cast -Wno-invalid-offsetof
-Winvalid-pch -Wlarger-than=len -Wunsafe-loop-optimizations
-Wlogical-op -Wlong-long
-Wmain -Wmaybe-uninitialized -Wmissing-braces -Wmissing-field-initializers
-Wmissing-format-attribute -Wmissing-include-dirs
-Wno-mudflap
-Wno-multichar -Wnonnull -Wno-overflow
-Woverlength-strings -Wpacked -Wpacked-bitfield-compat -Wpadded
-Wparentheses -Wpedantic-ms-format -Wno-pedantic-ms-format
-Wpointer-arith -Wno-pointer-to-int-cast
-Wredundant-decls
-Wreturn-type -Wsequence-point -Wshadow
-Wsign-compare -Wsign-conversion -Wstack-protector
-Wstack-usage=len -Wstrict-aliasing -Wstrict-aliasing=n
-Wstrict-overflow -Wstrict-overflow=n
-Wsuggest-attribute=[pure|const|noreturn]
-Wswitch -Wswitch-default -Wswitch-enum -Wsync-nand
-Wsystem-headers -Wtrampolines -Wtrigraphs -Wtype-limits -Wundef
-Wuninitialized -Wunknown-pragmas -Wno-pragmas
-Wunsuffixed-float-constants -Wunused -Wunused-function
-Wunused-label -Wunused-local-typedefs -Wunused-parameter
-Wno-unused-result -Wunused-value -Wunused-variable
-Wunused-but-set-parameter -Wunused-but-set-variable
-Wvariadic-macros -Wvector-operation-performance -Wvla
-Wvolatile-register-var -Wwrite-strings -Wzero-as-null-pointer-constant
-Wbad-function-cast -Wmissing-declarations
-Wmissing-parameter-type -Wmissing-prototypes -Wnested-externs
-Wold-style-declaration -Wold-style-definition
-Wstrict-prototypes -Wtraditional -Wtraditional-conversion
-Wdeclaration-after-statement -Wpointer-sign
-dletters -dumpspecs -dumpmachine -dumpversion
-fdbg-cnt-list -fdbg-cnt=counter-value-list
-fdisable-ipa-pass_name
-fdisable-rtl-pass_name
-fdisable-rtl-pass-name=range-list
-fdisable-tree-pass_name
-fdisable-tree-pass-name=range-list
-fdump-noaddr -fdump-unnumbered -fdump-unnumbered-links
-fdump-translation-unit[-n]
-fdump-class-hierarchy[-n]
-fdump-ipa-all -fdump-ipa-cgraph -fdump-ipa-inline
-fdump-passes
-fdump-statistics
-fdump-tree-all
-fdump-tree-original[-n]
-fdump-tree-optimized[-n]
-fdump-tree-cfg -fdump-tree-vcg -fdump-tree-alias
-fdump-tree-ch
-fdump-tree-ssa[-n] -fdump-tree-pre[-n]
-fdump-tree-ccp[-n] -fdump-tree-dce[-n]
-fdump-tree-gimple[-raw] -fdump-tree-mudflap[-n]
-fdump-tree-dom[-n]
-fdump-tree-dse[-n]
-fdump-tree-phiprop[-n]
-fdump-tree-phiopt[-n]
-fdump-tree-forwprop[-n]
-fdump-tree-copyrename[-n]
-fdump-tree-nrv -fdump-tree-vect
-fdump-tree-sink
-fdump-tree-sra[-n]
-fdump-tree-forwprop[-n]
-fdump-tree-fre[-n]
-fdump-tree-vrp[-n]
-ftree-vectorizer-verbose=n
-fdump-tree-storeccp[-n]
-fdump-final-insns=file
-fcompare-debug[=opts] -fcompare-debug-second
-feliminate-dwarf2-dups -feliminate-unused-debug-types
-feliminate-unused-debug-symbols -femit-class-debug-always
-fenable-kind-pass
-fenable-kind-pass=range-list
-fdebug-types-section
-fmem-report -fpre-ipa-mem-report -fpost-ipa-mem-report -fprofile-arcs
-frandom-seed=string -fsched-verbose=n
-fsel-sched-verbose -fsel-sched-dump-cfg -fsel-sched-pipelining-verbose
-fstack-usage -ftest-coverage -ftime-report -fvar-tracking
-fvar-tracking-assignments -fvar-tracking-assignments-toggle
-g -glevel -gtoggle -gcoff -gdwarf-version
-ggdb -grecord-gcc-switches -gno-record-gcc-switches
-gstabs -gstabs+ -gstrict-dwarf -gno-strict-dwarf
-gvms -gxcoff -gxcoff+
-fno-merge-debug-strings -fno-dwarf2-cfi-asm
-fdebug-prefix-map=old=new
-femit-struct-debug-baseonly -femit-struct-debug-reduced
-femit-struct-debug-detailed[=spec-list]
-p -pg -print-file-name=library -print-libgcc-file-name
-print-multi-directory -print-multi-lib -print-multi-os-directory
-print-prog-name=program -print-search-dirs -Q
-print-sysroot -print-sysroot-headers-suffix
-save-temps -save-temps=cwd -save-temps=obj -time[=file]
-falign-functions[=n] -falign-jumps[=n]
-falign-labels[=n] -falign-loops[=n] -fassociative-math
-fauto-inc-dec -fbranch-probabilities -fbranch-target-load-optimize
-fbranch-target-load-optimize2 -fbtr-bb-exclusive -fcaller-saves
-fcheck-data-deps -fcombine-stack-adjustments -fconserve-stack
-fcompare-elim -fcprop-registers -fcrossjumping
-fcse-follow-jumps -fcse-skip-blocks -fcx-fortran-rules
-fcx-limited-range
-fdata-sections -fdce -fdelayed-branch
-fdelete-null-pointer-checks -fdevirtualize -fdse
-fearly-inlining -fipa-sra -fexpensive-optimizations -ffat-lto-objects
-ffast-math -ffinite-math-only -ffloat-store -fexcess-precision=style
-fforward-propagate -ffp-contract=style -ffunction-sections
-fgcse -fgcse-after-reload -fgcse-las -fgcse-lm -fgraphite-identity
-fgcse-sm -fif-conversion -fif-conversion2 -findirect-inlining
-finline-functions -finline-functions-called-once -finline-limit=n
-finline-small-functions -fipa-cp -fipa-cp-clone -fipa-matrix-reorg
-fipa-pta -fipa-profile -fipa-pure-const -fipa-reference
-fira-algorithm=algorithm
-fira-region=region
-fira-loop-pressure -fno-ira-share-save-slots
-fno-ira-share-spill-slots -fira-verbose=n
-fivopts -fkeep-inline-functions -fkeep-static-consts
-floop-block -floop-flatten -floop-interchange -floop-strip-mine
-floop-parallelize-all -flto -flto-compression-level
-flto-partition=alg -flto-report -fmerge-all-constants
-fmerge-constants -fmodulo-sched -fmodulo-sched-allow-regmoves
-fmove-loop-invariants fmudflap -fmudflapir -fmudflapth -fno-branch-count-reg
-fno-default-inline
-fno-defer-pop -fno-function-cse -fno-guess-branch-probability
-fno-inline -fno-math-errno -fno-peephole -fno-peephole2
-fno-sched-interblock -fno-sched-spec -fno-signed-zeros
-fno-toplevel-reorder -fno-trapping-math -fno-zero-initialized-in-bss
-fomit-frame-pointer -foptimize-register-move -foptimize-sibling-calls
-fpartial-inlining -fpeel-loops -fpredictive-commoning
-fprefetch-loop-arrays
-fprofile-correction -fprofile-dir=path -fprofile-generate
-fprofile-generate=path
-fprofile-use -fprofile-use=path -fprofile-values
-freciprocal-math -free -fregmove -frename-registers -freorder-blocks
-freorder-blocks-and-partition -freorder-functions
-frerun-cse-after-loop -freschedule-modulo-scheduled-loops
-frounding-math -fsched2-use-superblocks -fsched-pressure
-fsched-spec-load -fsched-spec-load-dangerous
-fsched-stalled-insns-dep[=n] -fsched-stalled-insns[=n]
-fsched-group-heuristic -fsched-critical-path-heuristic
-fsched-spec-insn-heuristic -fsched-rank-heuristic
-fsched-last-insn-heuristic -fsched-dep-count-heuristic
-fschedule-insns -fschedule-insns2 -fsection-anchors
-fselective-scheduling -fselective-scheduling2
-fsel-sched-pipelining -fsel-sched-pipelining-outer-loops
-fshrink-wrap -fsignaling-nans -fsingle-precision-constant
-fsplit-ivs-in-unroller -fsplit-wide-types -fstack-protector
-fstack-protector-all -fstrict-aliasing -fstrict-overflow
-fthread-jumps -ftracer -ftree-bit-ccp
-ftree-builtin-call-dce -ftree-ccp -ftree-ch -ftree-copy-prop
-ftree-copyrename -ftree-dce -ftree-dominator-opts -ftree-dse
-ftree-forwprop -ftree-fre -ftree-loop-if-convert
-ftree-loop-if-convert-stores -ftree-loop-im
-ftree-phiprop -ftree-loop-distribution -ftree-loop-distribute-patterns
-ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize
-ftree-parallelize-loops=n -ftree-pre -ftree-pta -ftree-reassoc
-ftree-sink -ftree-sra -ftree-switch-conversion -ftree-tail-merge
-ftree-ter -ftree-vect-loop-version -ftree-vectorize -ftree-vrp
-funit-at-a-time -funroll-all-loops -funroll-loops
-funsafe-loop-optimizations -funsafe-math-optimizations -funswitch-loops
-fvariable-expansion-in-unroller -fvect-cost-model -fvpt -fweb
-fwhole-program -fwpa -fuse-linker-plugin
--param name=value
-O -O0 -O1 -O2 -O3 -Os -Ofast
-Aquestion=answer
-A-question[=answer]
-C -dD -dI -dM -dN
-Dmacro[=defn] -E -H
-idirafter dir
-include file -imacros file
-iprefix file -iwithprefix dir
-iwithprefixbefore dir -isystem dir
-imultilib dir -isysroot dir
-M -MM -MF -MG -MP -MQ -MT -nostdinc
-P -fdebug-cpp -ftrack-macro-expansion -fworking-directory
-remap -trigraphs -undef -Umacro
-Wp,option -Xpreprocessor option
-Wa,option -Xassembler option
object-file-name -llibrary
-nostartfiles -nodefaultlibs -nostdlib -pie -rdynamic
-s -static -static-libgcc -static-libstdc++ -shared
-shared-libgcc -symbolic
-T script -Wl,option -Xlinker option
-u symbol
-Bprefix -Idir -iplugindir=dir
-iquotedir -Ldir -specs=file -I-
--sysroot=dir
Adapteva Epiphany Options
-mhalf-reg-file -mprefer-short-insn-regs
-mbranch-cost=num -mcmove -mnops=num -msoft-cmpsf
-msplit-lohi -mpost-inc -mpost-modify -mstack-offset=num
-mround-nearest -mlong-calls -mshort-calls -msmall16
-mfp-mode=mode -mvect-double -max-vect-align=num
-msplit-vecmove-early -m1reg-reg
ARM Options
-mapcs-frame -mno-apcs-frame
-mabi=name
-mapcs-stack-check -mno-apcs-stack-check
-mapcs-float -mno-apcs-float
-mapcs-reentrant -mno-apcs-reentrant
-msched-prolog -mno-sched-prolog
-mlittle-endian -mbig-endian -mwords-little-endian
-mfloat-abi=name -mfpe
-mfp16-format=name
-mthumb-interwork -mno-thumb-interwork
-mcpu=name -march=name -mfpu=name
-mstructure-size-boundary=n
-mabort-on-noreturn
-mlong-calls -mno-long-calls
-msingle-pic-base -mno-single-pic-base
-mpic-register=reg
-mnop-fun-dllimport
-mcirrus-fix-invalid-insns -mno-cirrus-fix-invalid-insns
-mpoke-function-name
-mthumb -marm
-mtpcs-frame -mtpcs-leaf-frame
-mcaller-super-interworking -mcallee-super-interworking
-mtp=name -mtls-dialect=dialect
-mword-relocations
-mfix-cortex-m3-ldrd
-munaligned-access
AVR Options
-mmcu=mcu -maccumulate-args -mbranch-cost=cost
-mcall-prologues -mint8 -mno-interrupts -mrelax -mshort-calls
-mstrict-X -mtiny-stack
Blackfin Options
-mcpu=cpu[-sirevision] -msim -momit-leaf-frame-pointer -mno-omit-leaf-frame-pointer -mspecld-anomaly -mno-specld-anomaly -mcsync-anomaly -mno-csync-anomaly -mlow-64k -mno-low64k -mstack-check-l1 -mid-shared-library -mno-id-shared-library -mshared-library-id=n -mleaf-id-shared-library -mno-leaf-id-shared-library -msep-data -mno-sep-data -mlong-calls -mno-long-calls -mfast-fp -minline-plt -mmulticore -mcorea -mcoreb -msdram -micplb
C6X Options
-mbig-endian -mlittle-endian -march=cpu
-msim -msdata=sdata-type
CRIS Options
-mcpu=cpu -march=cpu -mtune=cpu
-mmax-stack-frame=n -melinux-stacksize=n
-metrax4 -metrax100 -mpdebug -mcc-init -mno-side-effects
-mstack-align -mdata-align -mconst-align
-m32-bit -m16-bit -m8-bit -mno-prologue-epilogue -mno-gotplt
-melf -maout -melinux -mlinux -sim -sim2
-mmul-bug-workaround -mno-mul-bug-workaround
CR16 Options
-mmac
-mcr16cplus -mcr16c
-msim -mint32 -mbit-ops
-mdata-model=model
Darwin Options
-all_load -allowable_client -arch -arch_errors_fatal
-arch_only -bind_at_load -bundle -bundle_loader
-client_name -compatibility_version -current_version
-dead_strip
-dependency-file -dylib_file -dylinker_install_name
-dynamic -dynamiclib -exported_symbols_list
-filelist -flat_namespace -force_cpusubtype_ALL
-force_flat_namespace -headerpad_max_install_names
-iframework
-image_base -init -install_name -keep_private_externs
-multi_module -multiply_defined -multiply_defined_unused
-noall_load -no_dead_strip_inits_and_terms
-nofixprebinding -nomultidefs -noprebind -noseglinkedit
-pagezero_size -prebind -prebind_all_twolevel_modules
-private_bundle -read_only_relocs -sectalign
-sectobjectsymbols -whyload -seg1addr
-sectcreate -sectobjectsymbols -sectorder
-segaddr -segs_read_only_addr -segs_read_write_addr
-seg_addr_table -seg_addr_table_filename -seglinkedit
-segprot -segs_read_only_addr -segs_read_write_addr
-single_module -static -sub_library -sub_umbrella
-twolevel_namespace -umbrella -undefined
-unexported_symbols_list -weak_reference_mismatches
-whatsloaded -F -gused -gfull -mmacosx-version-min=version
-mkernel -mone-byte-bool
DEC Alpha Options
-mno-fp-regs -msoft-float -malpha-as -mgas
-mieee -mieee-with-inexact -mieee-conformant
-mfp-trap-mode=mode -mfp-rounding-mode=mode
-mtrap-precision=mode -mbuild-constants
-mcpu=cpu-type -mtune=cpu-type
-mbwx -mmax -mfix -mcix
-mfloat-vax -mfloat-ieee
-mexplicit-relocs -msmall-data -mlarge-data
-msmall-text -mlarge-text
-mmemory-latency=time
DEC Alpha/VMS Options
-mvms-return-codes -mdebug-main=prefix -mmalloc64
FR30 Options
-msmall-model -mno-lsim
FRV Options
-mgpr-32 -mgpr-64 -mfpr-32 -mfpr-64
-mhard-float -msoft-float
-malloc-cc -mfixed-cc -mdword -mno-dword
-mdouble -mno-double
-mmedia -mno-media -mmuladd -mno-muladd
-mfdpic -minline-plt -mgprel-ro -multilib-library-pic
-mlinked-fp -mlong-calls -malign-labels
-mlibrary-pic -macc-4 -macc-8
-mpack -mno-pack -mno-eflags -mcond-move -mno-cond-move
-moptimize-membar -mno-optimize-membar
-mscc -mno-scc -mcond-exec -mno-cond-exec
-mvliw-branch -mno-vliw-branch
-mmulti-cond-exec -mno-multi-cond-exec -mnested-cond-exec
-mno-nested-cond-exec -mtomcat-stats
-mTLS -mtls
-mcpu=cpu
GNU/Linux Options
-mglibc -muclibc -mbionic -mandroid
-tno-android-cc -tno-android-ld
H8/300 Options
-mrelax -mh -ms -mn -mint32 -malign-300
HPPA Options
-march=architecture-type
-mbig-switch -mdisable-fpregs -mdisable-indexing
-mfast-indirect-calls -mgas -mgnu-ld -mhp-ld
-mfixed-range=register-range
-mjump-in-delay -mlinker-opt -mlong-calls
-mlong-load-store -mno-big-switch -mno-disable-fpregs
-mno-disable-indexing -mno-fast-indirect-calls -mno-gas
-mno-jump-in-delay -mno-long-load-store
-mno-portable-runtime -mno-soft-float
-mno-space-regs -msoft-float -mpa-risc-1-0
-mpa-risc-1-1 -mpa-risc-2-0 -mportable-runtime
-mschedule=cpu-type -mspace-regs -msio -mwsio
-munix=unix-std -nolibdld -static -threads
i386 and x86-64 Options
-mtune=cpu-type -march=cpu-type
-mfpmath=unit
-masm=dialect -mno-fancy-math-387
-mno-fp-ret-in-387 -msoft-float
-mno-wide-multiply -mrtd -malign-double
-mpreferred-stack-boundary=num
-mincoming-stack-boundary=num
-mcld -mcx16 -msahf -mmovbe -mcrc32
-mrecip -mrecip=opt
-mvzeroupper
-mmmx -msse -msse2 -msse3 -mssse3 -msse4.1 -msse4.2 -msse4 -mavx
-mavx2 -maes -mpclmul -mfsgsbase -mrdrnd -mf16c -mfma
-msse4a -m3dnow -mpopcnt -mabm -mbmi -mtbm -mfma4 -mxop -mlzcnt
-mbmi2 -mlwp -mthreads -mno-align-stringops -minline-all-stringops
-minline-stringops-dynamically -mstringop-strategy=alg
-mpush-args -maccumulate-outgoing-args -m128bit-long-double
-m96bit-long-double -mregparm=num -msseregparm
-mveclibabi=type -mvect8-ret-in-mem
-mpc32 -mpc64 -mpc80 -mstackrealign
-momit-leaf-frame-pointer -mno-red-zone -mno-tls-direct-seg-refs
-mcmodel=code-model -mabi=name
-m32 -m64 -mx32 -mlarge-data-threshold=num
-msse2avx -mfentry -m8bit-idiv
-mavx256-split-unaligned-load -mavx256-split-unaligned-store
i386 and x86-64 Windows Options
-mconsole -mcygwin -mno-cygwin -mdll
-mnop-fun-dllimport -mthread
-municode -mwin32 -mwindows -fno-set-stack-executable
IA-64 Options
-mbig-endian -mlittle-endian -mgnu-as -mgnu-ld -mno-pic
-mvolatile-asm-stop -mregister-names -msdata -mno-sdata
-mconstant-gp -mauto-pic -mfused-madd
-minline-float-divide-min-latency
-minline-float-divide-max-throughput
-mno-inline-float-divide
-minline-int-divide-min-latency
-minline-int-divide-max-throughput
-mno-inline-int-divide
-minline-sqrt-min-latency -minline-sqrt-max-throughput
-mno-inline-sqrt
-mdwarf2-asm -mearly-stop-bits
-mfixed-range=register-range -mtls-size=tls-size
-mtune=cpu-type -milp32 -mlp64
-msched-br-data-spec -msched-ar-data-spec -msched-control-spec
-msched-br-in-data-spec -msched-ar-in-data-spec -msched-in-control-spec
-msched-spec-ldc -msched-spec-control-ldc
-msched-prefer-non-data-spec-insns -msched-prefer-non-control-spec-insns
-msched-stop-bits-after-every-cycle -msched-count-spec-in-critical-path
-msel-sched-dont-check-control-spec -msched-fp-mem-deps-zero-cost
-msched-max-memory-insns-hard-limit -msched-max-memory-insns=max-insns
IA-64/VMS Options
-mvms-return-codes -mdebug-main=prefix -mmalloc64
LM32 Options
-mbarrel-shift-enabled -mdivide-enabled -mmultiply-enabled
-msign-extend-enabled -muser-enabled
M32R/D Options
-m32r2 -m32rx -m32r
-mdebug
-malign-loops -mno-align-loops
-missue-rate=number
-mbranch-cost=number
-mmodel=code-size-model-type
-msdata=sdata-type
-mno-flush-func -mflush-func=name
-mno-flush-trap -mflush-trap=number
-G num
M32C Options
-mcpu=cpu -msim -memregs=number
M680x0 Options
-march=arch -mcpu=cpu -mtune=tune
-m68000 -m68020 -m68020-40 -m68020-60 -m68030 -m68040
-m68060 -mcpu32 -m5200 -m5206e -m528x -m5307 -m5407
-mcfv4e -mbitfield -mno-bitfield -mc68000 -mc68020
-mnobitfield -mrtd -mno-rtd -mdiv -mno-div -mshort
-mno-short -mhard-float -m68881 -msoft-float -mpcrel
-malign-int -mstrict-align -msep-data -mno-sep-data
-mshared-library-id=n -mid-shared-library -mno-id-shared-library
-mxgot -mno-xgot
MCore Options
-mhardlit -mno-hardlit -mdiv -mno-div -mrelax-immediates
-mno-relax-immediates -mwide-bitfields -mno-wide-bitfields
-m4byte-functions -mno-4byte-functions -mcallgraph-data
-mno-callgraph-data -mslow-bytes -mno-slow-bytes -mno-lsim
-mlittle-endian -mbig-endian -m210 -m340 -mstack-increment
MeP Options
-mabsdiff -mall-opts -maverage -mbased=n -mbitops
-mc=n -mclip -mconfig=name -mcop -mcop32 -mcop64 -mivc2
-mdc -mdiv -meb -mel -mio-volatile -ml -mleadz -mm -mminmax
-mmult -mno-opts -mrepeat -ms -msatur -msdram -msim -msimnovec -mtf
-mtiny=n
MicroBlaze Options
-msoft-float -mhard-float -msmall-divides -mcpu=cpu
-mmemcpy -mxl-soft-mul -mxl-soft-div -mxl-barrel-shift
-mxl-pattern-compare -mxl-stack-check -mxl-gp-opt -mno-clearbss
-mxl-multiply-high -mxl-float-convert -mxl-float-sqrt
-mxl-mode-app-model
MIPS Options
-EL -EB -march=arch -mtune=arch
-mips1 -mips2 -mips3 -mips4 -mips32 -mips32r2
-mips64 -mips64r2
-mips16 -mno-mips16 -mflip-mips16
-minterlink-mips16 -mno-interlink-mips16
-mabi=abi -mabicalls -mno-abicalls
-mshared -mno-shared -mplt -mno-plt -mxgot -mno-xgot
-mgp32 -mgp64 -mfp32 -mfp64 -mhard-float -msoft-float
-msingle-float -mdouble-float -mdsp -mno-dsp -mdspr2 -mno-dspr2
-mfpu=fpu-type
-msmartmips -mno-smartmips
-mpaired-single -mno-paired-single -mdmx -mno-mdmx
-mips3d -mno-mips3d -mmt -mno-mt -mllsc -mno-llsc
-mlong64 -mlong32 -msym32 -mno-sym32
-Gnum -mlocal-sdata -mno-local-sdata
-mextern-sdata -mno-extern-sdata -mgpopt -mno-gopt
-membedded-data -mno-embedded-data
-muninit-const-in-rodata -mno-uninit-const-in-rodata
-mcode-readable=setting
-msplit-addresses -mno-split-addresses
-mexplicit-relocs -mno-explicit-relocs
-mcheck-zero-division -mno-check-zero-division
-mdivide-traps -mdivide-breaks
-mmemcpy -mno-memcpy -mlong-calls -mno-long-calls
-mmad -mno-mad -mfused-madd -mno-fused-madd -nocpp
-mfix-24k -mno-fix-24k
-mfix-r4000 -mno-fix-r4000 -mfix-r4400 -mno-fix-r4400
-mfix-r10000 -mno-fix-r10000 -mfix-vr4120 -mno-fix-vr4120
-mfix-vr4130 -mno-fix-vr4130 -mfix-sb1 -mno-fix-sb1
-mflush-func=func -mno-flush-func
-mbranch-cost=num -mbranch-likely -mno-branch-likely
-mfp-exceptions -mno-fp-exceptions
-mvr4130-align -mno-vr4130-align -msynci -mno-synci
-mrelax-pic-calls -mno-relax-pic-calls -mmcount-ra-address
MMIX Options
-mlibfuncs -mno-libfuncs -mepsilon -mno-epsilon -mabi=gnu
-mabi=mmixware -mzero-extend -mknuthdiv -mtoplevel-symbols
-melf -mbranch-predict -mno-branch-predict -mbase-addresses
-mno-base-addresses -msingle-exit -mno-single-exit
MN10300 Options
-mmult-bug -mno-mult-bug
-mno-am33 -mam33 -mam33-2 -mam34
-mtune=cpu-type
-mreturn-pointer-on-d0
-mno-crt0 -mrelax -mliw -msetlb
PDP-11 Options
-mfpu -msoft-float -mac0 -mno-ac0 -m40 -m45 -m10
-mbcopy -mbcopy-builtin -mint32 -mno-int16
-mint16 -mno-int32 -mfloat32 -mno-float64
-mfloat64 -mno-float32 -mabshi -mno-abshi
-mbranch-expensive -mbranch-cheap
-munix-asm -mdec-asm
picoChip Options
-mae=ae_type -mvliw-lookahead=N
-msymbol-as-address -mno-inefficient-warnings
PowerPC Options See RS/6000 and PowerPC Options.
RL78 Options
-msim -mmul=none -mmul=g13 -mmul=rl78
RS/6000 and PowerPC Options
-mcpu=cpu-type
-mtune=cpu-type
-mcmodel=code-model
-mpower -mno-power -mpower2 -mno-power2
-mpowerpc -mpowerpc64 -mno-powerpc
-maltivec -mno-altivec
-mpowerpc-gpopt -mno-powerpc-gpopt
-mpowerpc-gfxopt -mno-powerpc-gfxopt
-mmfcrf -mno-mfcrf -mpopcntb -mno-popcntb -mpopcntd -mno-popcntd
-mfprnd -mno-fprnd
-mcmpb -mno-cmpb -mmfpgpr -mno-mfpgpr -mhard-dfp -mno-hard-dfp
-mnew-mnemonics -mold-mnemonics
-mfull-toc -mminimal-toc -mno-fp-in-toc -mno-sum-in-toc
-m64 -m32 -mxl-compat -mno-xl-compat -mpe
-malign-power -malign-natural
-msoft-float -mhard-float -mmultiple -mno-multiple
-msingle-float -mdouble-float -msimple-fpu
-mstring -mno-string -mupdate -mno-update
-mavoid-indexed-addresses -mno-avoid-indexed-addresses
-mfused-madd -mno-fused-madd -mbit-align -mno-bit-align
-mstrict-align -mno-strict-align -mrelocatable
-mno-relocatable -mrelocatable-lib -mno-relocatable-lib
-mtoc -mno-toc -mlittle -mlittle-endian -mbig -mbig-endian
-mdynamic-no-pic -maltivec -mswdiv -msingle-pic-base
-mprioritize-restricted-insns=priority
-msched-costly-dep=dependence_type
-minsert-sched-nops=scheme
-mcall-sysv -mcall-netbsd
-maix-struct-return -msvr4-struct-return
-mabi=abi-type -msecure-plt -mbss-plt
-mblock-move-inline-limit=num
-misel -mno-isel
-misel=yes -misel=no
-mspe -mno-spe
-mspe=yes -mspe=no
-mpaired
-mgen-cell-microcode -mwarn-cell-microcode
-mvrsave -mno-vrsave
-mmulhw -mno-mulhw
-mdlmzb -mno-dlmzb
-mfloat-gprs=yes -mfloat-gprs=no -mfloat-gprs=single -mfloat-gprs=double
-mprototype -mno-prototype
-msim -mmvme -mads -myellowknife -memb -msdata
-msdata=opt -mvxworks -G num -pthread
-mrecip -mrecip=opt -mno-recip -mrecip-precision
-mno-recip-precision
-mveclibabi=type -mfriz -mno-friz
-mpointers-to-nested-functions -mno-pointers-to-nested-functions
-msave-toc-indirect -mno-save-toc-indirect
RX Options
-m64bit-doubles -m32bit-doubles -fpu -nofpu
-mcpu=
-mbig-endian-data -mlittle-endian-data
-msmall-data
-msim -mno-sim
-mas100-syntax -mno-as100-syntax
-mrelax
-mmax-constant-size=
-mint-register=
-mpid
-msave-acc-in-interrupts
S/390 and zSeries Options
-mtune=cpu-type -march=cpu-type
-mhard-float -msoft-float -mhard-dfp -mno-hard-dfp
-mlong-double-64 -mlong-double-128
-mbackchain -mno-backchain -mpacked-stack -mno-packed-stack
-msmall-exec -mno-small-exec -mmvcle -mno-mvcle
-m64 -m31 -mdebug -mno-debug -mesa -mzarch
-mtpf-trace -mno-tpf-trace -mfused-madd -mno-fused-madd
-mwarn-framesize -mwarn-dynamicstack -mstack-size -mstack-guard
Score Options
-meb -mel
-mnhwloop
-muls
-mmac
-mscore5 -mscore5u -mscore7 -mscore7d
SH Options
-m1 -m2 -m2e
-m2a-nofpu -m2a-single-only -m2a-single -m2a
-m3 -m3e
-m4-nofpu -m4-single-only -m4-single -m4
-m4a-nofpu -m4a-single-only -m4a-single -m4a -m4al
-m5-64media -m5-64media-nofpu
-m5-32media -m5-32media-nofpu
-m5-compact -m5-compact-nofpu
-mb -ml -mdalign -mrelax
-mbigtable -mfmovd -mhitachi -mrenesas -mno-renesas -mnomacsave
-mieee -mno-ieee -mbitops -misize -minline-ic_invalidate -mpadstruct
-mspace -mprefergot -musermode -multcost=number -mdiv=strategy
-mdivsi3_libfunc=name -mfixed-range=register-range
-madjust-unroll -mindexed-addressing -mgettrcost=number -mpt-fixed
-maccumulate-outgoing-args -minvalid-symbols -msoft-atomic
-mbranch-cost=num -mcbranchdi -mcmpeqdi -mfused-madd -mpretend-cmove
Solaris 2 Options
-mimpure-text -mno-impure-text
-pthreads -pthread
SPARC Options
-mcpu=cpu-type
-mtune=cpu-type
-mcmodel=code-model
-mmemory-model=mem-model
-m32 -m64 -mapp-regs -mno-app-regs
-mfaster-structs -mno-faster-structs -mflat -mno-flat
-mfpu -mno-fpu -mhard-float -msoft-float
-mhard-quad-float -msoft-quad-float
-mlittle-endian
-mstack-bias -mno-stack-bias
-munaligned-doubles -mno-unaligned-doubles
-mv8plus -mno-v8plus -mvis -mno-vis
-mvis2 -mno-vis2 -mvis3 -mno-vis3
-mfmaf -mno-fmaf -mpopc -mno-popc
-mfix-at697f
SPU Options
-mwarn-reloc -merror-reloc
-msafe-dma -munsafe-dma
-mbranch-hints
-msmall-mem -mlarge-mem -mstdmain
-mfixed-range=register-range
-mea32 -mea64
-maddress-space-conversion -mno-address-space-conversion
-mcache-size=cache-size
-matomic-updates -mno-atomic-updates
System V Options
-Qy -Qn -YP,paths -Ym,dir
TILE-Gx Options
-mcpu=cpu -m32 -m64
TILEPro Options
-mcpu=cpu -m32
V850 Options
-mlong-calls -mno-long-calls -mep -mno-ep
-mprolog-function -mno-prolog-function -mspace
-mtda=n -msda=n -mzda=n
-mapp-regs -mno-app-regs
-mdisable-callt -mno-disable-callt
-mv850e2v3
-mv850e2
-mv850e1 -mv850es
-mv850e
-mv850 -mbig-switch
VAX Options
-mg -mgnu -munix
VxWorks Options
-mrtp -non-static -Bstatic -Bdynamic
-Xbind-lazy -Xbind-now
x86-64 Options See i386 and x86-64 Options.
Xstormy16 Options
-msim
Xtensa Options
-mconst16 -mno-const16
-mfused-madd -mno-fused-madd
-mforce-no-pic
-mserialize-volatile -mno-serialize-volatile
-mtext-section-literals -mno-text-section-literals
-mtarget-align -mno-target-align
-mlongcalls -mno-longcalls
zSeries Options
See S/390 and zSeries Options.
-fcall-saved-reg -fcall-used-reg
-ffixed-reg -fexceptions
-fnon-call-exceptions -funwind-tables
-fasynchronous-unwind-tables
-finhibit-size-directive -finstrument-functions
-finstrument-functions-exclude-function-list=sym,sym,...
-finstrument-functions-exclude-file-list=file,file,...
-fno-common -fno-ident
-fpcc-struct-return -fpic -fPIC -fpie -fPIE
-fno-jump-tables
-frecord-gcc-switches
-freg-struct-return -fshort-enums
-fshort-double -fshort-wchar
-fverbose-asm -fpack-struct[=n] -fstack-check
-fstack-limit-register=reg -fstack-limit-symbol=sym
-fno-stack-limit -fsplit-stack
-fleading-underscore -ftls-model=model
-ftrapv -fwrapv -fbounds-check
-fvisibility -fstrict-volatile-bitfields
Compilation can involve up to four stages: preprocessing, compilation proper, assembly and linking, always in that order. GCC is capable of preprocessing and compiling several files either into several assembler input files, or into one assembler input file; then each assembler input file produces an object file, and linking combines all the object files (those newly compiled, and those specified as input) into an executable file.
For any given input file, the file name suffix determines what kind of compilation is done:
.c.i.ii.m.mi.mm.M.mii.h.cc.cp.cxx.cpp.CPP.c++.C.mm.M.mii.hh.H.hp.hxx.hpp.HPP.h++.tcc.f.for.ftn.F.FOR.fpp.FPP.FTN.f90.f95.f03.f08.F90.F95.F03.F08.go.ads.adb.s.S.sxYou can specify the input language explicitly with the -x option:
-x language c c-header cpp-output
c++ c++-header c++-cpp-output
objective-c objective-c-header objective-c-cpp-output
objective-c++ objective-c++-header objective-c++-cpp-output
assembler assembler-with-cpp
ada
f77 f77-cpp-input f95 f95-cpp-input
go
java
-x none-pass-exit-codesIf you only want some of the stages of compilation, you can use -x (or filename suffixes) to tell gcc where to start, and one of the options -c, -S, or -E to say where gcc is to stop. Note that some combinations (for example, ‘-x cpp-output -E’) instruct gcc to do nothing at all.
-cBy default, the object file name for a source file is made by replacing the suffix ‘.c’, ‘.i’, ‘.s’, etc., with ‘.o’.
Unrecognized input files, not requiring compilation or assembly, are
ignored.
-SBy default, the assembler file name for a source file is made by replacing the suffix ‘.c’, ‘.i’, etc., with ‘.s’.
Input files that don't require compilation are ignored.
-EInput files that don't require preprocessing are ignored.
-o fileIf -o is not specified, the default is to put an executable
file in a.out, the object file for
source.suffix in source.o, its
assembler file in source.s, a precompiled header file in
source.suffix.gch, and all preprocessed C source on
standard output.
-v-###./-_.
This is useful for shell scripts to capture the driver-generated command lines.
-pipe--help--target-help--help={class|[^]qualifier}[,...]These are the supported qualifiers:
Thus for example to display all the undocumented target-specific switches supported by the compiler the following can be used:
--help=target,undocumented
The sense of a qualifier can be inverted by prefixing it with the ‘^’ character, so for example to display all binary warning options (i.e., ones that are either on or off and that do not take an argument) that have a description, use:
--help=warnings,^joined,^undocumented
The argument to --help= should not consist solely of inverted qualifiers.
Combining several classes is possible, although this usually restricts the output by so much that there is nothing to display. One case where it does work however is when one of the classes is target. So for example to display all the target-specific optimization options the following can be used:
--help=target,optimizers
The --help= option can be repeated on the command line. Each successive use will display its requested class of options, skipping those that have already been displayed.
If the -Q option appears on the command line before the --help= option, then the descriptive text displayed by --help= is changed. Instead of describing the displayed options, an indication is given as to whether the option is enabled, disabled or set to a specific value (assuming that the compiler knows this at the point where the --help= option is used).
Here is a truncated example from the ARM port of gcc:
% gcc -Q -mabi=2 --help=target -c
The following options are target specific:
-mabi= 2
-mabort-on-noreturn [disabled]
-mapcs [disabled]
The output is sensitive to the effects of previous command-line options, so for example it is possible to find out which optimizations are enabled at -O2 by using:
-Q -O2 --help=optimizers
Alternatively you can discover which binary optimizations are enabled by -O3 by using:
gcc -c -Q -O3 --help=optimizers > /tmp/O3-opts
gcc -c -Q -O2 --help=optimizers > /tmp/O2-opts
diff /tmp/O2-opts /tmp/O3-opts | grep enabled
-no-canonical-prefixes--version-wrappergcc -c t.c -wrapper gdb,--args
This will invoke all subprograms of gcc under
‘gdb --args’, thus the invocation of cc1 will be
‘gdb --args cc1 ...’.
-fplugin=name.so-fplugin-arg-name-key=value-fdump-ada-spec[-slim]-fdump-go-spec=fileconst,
type, var, and func declarations which may be a
useful way to start writing a Go interface to code written in some
other language.
@fileOptions in file are separated by whitespace. A whitespace character may be included in an option by surrounding the entire option in either single or double quotes. Any character (including a backslash) may be included by prefixing the character to be included with a backslash. The file may itself contain additional @file options; any such options will be processed recursively.
C++ source files conventionally use one of the suffixes ‘.C’, ‘.cc’, ‘.cpp’, ‘.CPP’, ‘.c++’, ‘.cp’, or ‘.cxx’; C++ header files often use ‘.hh’, ‘.hpp’, ‘.H’, or (for shared template code) ‘.tcc’; and preprocessed C++ files use the suffix ‘.ii’. GCC recognizes files with these names and compiles them as C++ programs even if you call the compiler the same way as for compiling C programs (usually with the name gcc).
However, the use of gcc does not add the C++ library. g++ is a program that calls GCC and treats ‘.c’, ‘.h’ and ‘.i’ files as C++ source files instead of C source files unless -x is used, and automatically specifies linking against the C++ library. This program is also useful when precompiling a C header file with a ‘.h’ extension for use in C++ compilations. On many systems, g++ is also installed with the name c++.
When you compile C++ programs, you may specify many of the same command-line options that you use for compiling programs in any language; or command-line options meaningful for C and related languages; or options that are meaningful only for C++ programs. See Options Controlling C Dialect, for explanations of options for languages related to C. See Options Controlling C++ Dialect, for explanations of options that are meaningful only for C++ programs.
The following options control the dialect of C (or languages derived from C, such as C++, Objective-C and Objective-C++) that the compiler accepts:
-ansiThis turns off certain features of GCC that are incompatible with ISO
C90 (when compiling C code), or of standard C++ (when compiling C++ code),
such as the asm and typeof keywords, and
predefined macros such as unix and vax that identify the
type of system you are using. It also enables the undesirable and
rarely used ISO trigraph feature. For the C compiler,
it disables recognition of C++ style ‘//’ comments as well as
the inline keyword.
The alternate keywords __asm__, __extension__,
__inline__ and __typeof__ continue to work despite
-ansi. You would not want to use them in an ISO C program, of
course, but it is useful to put them in header files that might be included
in compilations done with -ansi. Alternate predefined macros
such as __unix__ and __vax__ are also available, with or
without -ansi.
The -ansi option does not cause non-ISO programs to be rejected gratuitously. For that, -pedantic is required in addition to -ansi. See Warning Options.
The macro __STRICT_ANSI__ is predefined when the -ansi
option is used. Some header files may notice this macro and refrain
from declaring certain functions or defining certain macros that the
ISO standard doesn't call for; this is to avoid interfering with any
programs that might use these names for other things.
Functions that would normally be built in but do not have semantics
defined by ISO C (such as alloca and ffs) are not built-in
functions when -ansi is used. See Other built-in functions provided by GCC, for details of the functions
affected.
-std=The compiler can accept several base standards, such as ‘c90’ or
‘c++98’, and GNU dialects of those standards, such as
‘gnu90’ or ‘gnu++98’. By specifying a base standard, the
compiler will accept all programs following that standard and those
using GNU extensions that do not contradict it. For example,
‘-std=c90’ turns off certain features of GCC that are
incompatible with ISO C90, such as the asm and typeof
keywords, but not other GNU extensions that do not have a meaning in
ISO C90, such as omitting the middle term of a ?:
expression. On the other hand, by specifying a GNU dialect of a
standard, all features the compiler support are enabled, even when
those features change the meaning of the base standard and some
strict-conforming programs may be rejected. The particular standard
is used by -pedantic to identify which features are GNU
extensions given that version of the standard. For example
‘-std=gnu90 -pedantic’ would warn about C++ style ‘//’
comments, while ‘-std=gnu99 -pedantic’ would not.
A value for this option must be provided; possible values are
-fgnu89-inlineinline functions when in C99 mode.
See An Inline Function is As Fast As a Macro. This option
is accepted and ignored by GCC versions 4.1.3 up to but not including
4.3. In GCC versions 4.3 and later it changes the behavior of GCC in
C99 mode. Using this option is roughly equivalent to adding the
gnu_inline function attribute to all inline functions
(see Function Attributes).
The option -fno-gnu89-inline explicitly tells GCC to use the
C99 semantics for inline when in C99 or gnu99 mode (i.e., it
specifies the default behavior). This option was first supported in
GCC 4.3. This option is not supported in -std=c90 or
-std=gnu90 mode.
The preprocessor macros __GNUC_GNU_INLINE__ and
__GNUC_STDC_INLINE__ may be used to check which semantics are
in effect for inline functions. See Common Predefined Macros.
-aux-info filenameBesides declarations, the file indicates, in comments, the origin of
each declaration (source file and line), whether the declaration was
implicit, prototyped or unprototyped (‘I’, ‘N’ for new or
‘O’ for old, respectively, in the first character after the line
number and the colon), and whether it came from a declaration or a
definition (‘C’ or ‘F’, respectively, in the following
character). In the case of function definitions, a K&R-style list of
arguments followed by their declarations is also provided, inside
comments, after the declaration.
-fallow-parameterless-variadic-functionsAlthough it is possible to define such a function, this is not very
useful as it is not possible to read the arguments. This is only
supported for C as this construct is allowed by C++.
-fno-asmasm, inline or typeof as a
keyword, so that code can use these words as identifiers. You can use
the keywords __asm__, __inline__ and __typeof__
instead. -ansi implies -fno-asm.
In C++, this switch only affects the typeof keyword, since
asm and inline are standard keywords. You may want to
use the -fno-gnu-keywords flag instead, which has the same
effect. In C99 mode (-std=c99 or -std=gnu99), this
switch only affects the asm and typeof keywords, since
inline is a standard keyword in ISO C99.
-fno-builtin-fno-builtin-functionGCC normally generates special code to handle certain built-in functions
more efficiently; for instance, calls to alloca may become single
instructions which adjust the stack directly, and calls to memcpy
may become inline copy loops. The resulting code is often both smaller
and faster, but since the function calls no longer appear as such, you
cannot set a breakpoint on those calls, nor can you change the behavior
of the functions by linking with a different library. In addition,
when a function is recognized as a built-in function, GCC may use
information about that function to warn about problems with calls to
that function, or to generate more efficient code, even if the
resulting code still contains calls to that function. For example,
warnings are given with -Wformat for bad calls to
printf, when printf is built in, and strlen is
known not to modify global memory.
With the -fno-builtin-function option only the built-in function function is disabled. function must not begin with ‘__builtin_’. If a function is named that is not built-in in this version of GCC, this option is ignored. There is no corresponding -fbuiltin-function option; if you wish to enable built-in functions selectively when using -fno-builtin or -ffreestanding, you may define macros such as:
#define abs(n) __builtin_abs ((n))
#define strcpy(d, s) __builtin_strcpy ((d), (s))
-fhostedmain has a return
type of int. Examples are nearly everything except a kernel.
This is equivalent to -fno-freestanding.
-ffreestandingmain. The most obvious example is an OS kernel.
This is equivalent to -fno-hosted.
See Language Standards Supported by GCC, for details of
freestanding and hosted environments.
-fopenmp#pragma omp in C/C++ and
!$omp in Fortran. When -fopenmp is specified, the
compiler generates parallel code according to the OpenMP Application
Program Interface v3.0 http://www.openmp.org/. This option
implies -pthread, and thus is only supported on targets that
have support for -pthread.
-fgnu-tmFor more information on GCC's support for transactional memory, See The GNU Transactional Memory Library.
Note that the transactional memory feature is not supported with
non-call exceptions (-fnon-call-exceptions).
-fms-extensionsIn C++ code, this allows member names in structures to be similar to previous types declarations.
typedef int UOW;
struct ABC {
UOW UOW;
};
Some cases of unnamed fields in structures and unions are only
accepted with this option. See Unnamed struct/union fields within structs/unions, for details.
-fplan9-extensionsThis enables -fms-extensions, permits passing pointers to
structures with anonymous fields to functions that expect pointers to
elements of the type of the field, and permits referring to anonymous
fields declared using a typedef. See Unnamed struct/union fields within structs/unions, for details. This is only
supported for C, not C++.
-trigraphs-no-integrated-cppThe semantics of this option will change if "cc1", "cc1plus", and "cc1obj" are merged.
-traditional-traditional-cpp-fcond-mismatch-flax-vector-conversions-funsigned-charchar be unsigned, like unsigned char.
Each kind of machine has a default for what char should
be. It is either like unsigned char by default or like
signed char by default.
Ideally, a portable program should always use signed char or
unsigned char when it depends on the signedness of an object.
But many programs have been written to use plain char and
expect it to be signed, or expect it to be unsigned, depending on the
machines they were written for. This option, and its inverse, let you
make such a program work with the opposite default.
The type char is always a distinct type from each of
signed char or unsigned char, even though its behavior
is always just like one of those two.
-fsigned-charchar be signed, like signed char.
Note that this is equivalent to -fno-unsigned-char, which is
the negative form of -funsigned-char. Likewise, the option
-fno-signed-char is equivalent to -funsigned-char.
-fsigned-bitfields-funsigned-bitfields-fno-signed-bitfields-fno-unsigned-bitfieldssigned or unsigned. By
default, such a bit-field is signed, because this is consistent: the
basic integer types such as int are signed types.
This section describes the command-line options that are only meaningful
for C++ programs; but you can also use most of the GNU compiler options
regardless of what language your program is in. For example, you
might compile a file firstClass.C like this:
g++ -g -frepo -O -c firstClass.C
In this example, only -frepo is an option meant only for C++ programs; you can use the other options with any language supported by GCC.
Here is a list of options that are only for compiling C++ programs:
-fabi-version=nThe default is version 2.
Version 3 corrects an error in mangling a constant address as a template argument.
Version 4, which first appeared in G++ 4.5, implements a standard mangling for vector types.
Version 5, which first appeared in G++ 4.6, corrects the mangling of attribute const/volatile on function pointer types, decltype of a plain decl, and use of a function parameter in the declaration of another parameter.
Version 6, which first appeared in G++ 4.7, corrects the promotion behavior of C++11 scoped enums and the mangling of template argument packs, const/static_cast, prefix ++ and –, and a class scope function used as a template argument.
See also -Wabi.
-fno-access-control-fcheck-newoperator new is non-null
before attempting to modify the storage allocated. This check is
normally unnecessary because the C++ standard specifies that
operator new will only return 0 if it is declared
‘throw()’, in which case the compiler will always check the
return value even without this option. In all other cases, when
operator new has a non-empty exception specification, memory
exhaustion is signalled by throwing std::bad_alloc. See also
‘new (nothrow)’.
-fconserve-spacemain() has
completed, you may have an object that is being destroyed twice because
two definitions were merged.
This option is no longer useful on most targets, now that support has
been added for putting variables into BSS without making them common.
-fconstexpr-depth=n-fdeduce-init-list template <class T> auto forward(T t) -> decltype (realfn (t))
{
return realfn (t);
}
void f()
{
forward({1,2}); // call forward<std::initializer_list<int>>
}
This deduction was implemented as a possible extension to the
originally proposed semantics for the C++11 standard, but was not part
of the final standard, so it is disabled by default. This option is
deprecated, and may be removed in a future version of G++.
-ffriend-injectionThis option is for compatibility, and may be removed in a future
release of G++.
-fno-elide-constructors-fno-enforce-eh-specs-ffor-scope-fno-for-scopeThe default if neither flag is given to follow the standard,
but to allow and give a warning for old-style code that would
otherwise be invalid, or have different behavior.
-fno-gnu-keywordstypeof as a keyword, so that code can use this
word as an identifier. You can use the keyword __typeof__ instead.
-ansi implies -fno-gnu-keywords.
-fno-implicit-templates-fno-implicit-inline-templates-fno-implement-inlines-fms-extensions-fno-nonansi-builtinsffs, alloca, _exit,
index, bzero, conjf, and other related functions.
-fnothrow-optthrow() exception specification as though it were a
noexcept specification to reduce or eliminate the text size
overhead relative to a function with no exception specification. If
the function has local variables of types with non-trivial
destructors, the exception specification will actually make the
function smaller because the EH cleanups for those variables can be
optimized away. The semantic effect is that an exception thrown out of
a function with such an exception specification will result in a call
to terminate rather than unexpected.
-fno-operator-namesand, bitand,
bitor, compl, not, or and xor as
synonyms as keywords.
-fno-optional-diags-fpermissive-fno-pretty-templatesvoid f(T) [with T = int]
rather than void f(int)) so that it's clear which template is
involved. When an error message refers to a specialization of a class
template, the compiler will omit any template arguments that match
the default template arguments for that template. If either of these
behaviors make it harder to understand the error message rather than
easier, using -fno-pretty-templates will disable them.
-frepo-fno-rttivoid * or to
unambiguous base classes.
-fstats-fstrict-enums-ftemplate-depth=n-fno-threadsafe-statics-fuse-cxa-atexit__cxa_atexit function rather than the atexit function.
This option is required for fully standards-compliant handling of static
destructors, but will only work if your C library supports
__cxa_atexit.
-fno-use-cxa-get-exception-ptr__cxa_get_exception_ptr runtime routine. This
will cause std::uncaught_exception to be incorrect, but is necessary
if the runtime routine is not available.
-fvisibility-inlines-hiddenThe effect of this is that GCC may, effectively, mark inline methods with
__attribute__ ((visibility ("hidden"))) so that they do not
appear in the export table of a DSO and do not require a PLT indirection
when used within the DSO. Enabling this option can have a dramatic effect
on load and link times of a DSO as it massively reduces the size of the
dynamic export table when the library makes heavy use of templates.
The behavior of this switch is not quite the same as marking the methods as hidden directly, because it does not affect static variables local to the function or cause the compiler to deduce that the function is defined in only one shared object.
You may mark a method as having a visibility explicitly to negate the effect of the switch for that method. For example, if you do want to compare pointers to a particular inline method, you might mark it as having default visibility. Marking the enclosing class with explicit visibility will have no effect.
Explicitly instantiated inline methods are unaffected by this option
as their linkage might otherwise cross a shared library boundary.
See Template Instantiation.
-fvisibility-ms-compatThe flag makes these changes to GCC's linkage model:
hidden, like
-fvisibility=hidden.
In new code it is better to use -fvisibility=hidden and export those classes that are intended to be externally visible. Unfortunately it is possible for code to rely, perhaps accidentally, on the Visual Studio behavior.
Among the consequences of these changes are that static data members
of the same type with the same name but defined in different shared
objects will be different, so changing one will not change the other;
and that pointers to function members defined in different shared
objects may not compare equal. When this flag is given, it is a
violation of the ODR to define types with the same name differently.
-fno-weak-nostdinc++In addition, these optimization, warning, and code generation options have meanings only for C++ programs:
-fno-default-inline-Wabi (C, Objective-C, C++ and Objective-C++ only)You should rewrite your code to avoid these warnings if you are concerned about the fact that code generated by G++ may not be binary compatible with code generated by other compilers.
The known incompatibilities in -fabi-version=2 (the default) include:
extern int N;
template <int &> struct S {};
void n (S<N>) {2}
This is fixed in -fabi-version=3.
__attribute ((vector_size)) are
mangled in a non-standard way that does not allow for overloading of
functions taking vectors of different sizes.
The mangling is changed in -fabi-version=4.
The known incompatibilities in -fabi-version=1 include:
struct A { virtual void f(); int f1 : 1; };
struct B : public A { int f2 : 1; };
In this case, G++ will place B::f2 into the same byte
asA::f1; other compilers will not. You can avoid this problem
by explicitly padding A so that its size is a multiple of the
byte size on your platform; that will cause G++ and other compilers to
layout B identically.
struct A { virtual void f(); char c1; };
struct B { B(); char c2; };
struct C : public A, public virtual B {};
In this case, G++ will not place B into the tail-padding for
A; other compilers will. You can avoid this problem by
explicitly padding A so that its size is a multiple of its
alignment (ignoring virtual base classes); that will cause G++ and other
compilers to layout C identically.
union U { int i : 4096; };
Assuming that an int does not have 4096 bits, G++ will make the
union too small by the number of bits in an int.
struct A {};
struct B {
A a;
virtual void f ();
};
struct C : public B, public A {};
G++ will place the A base class of C at a nonzero offset;
it should be placed at offset zero. G++ mistakenly believes that the
A data member of B is already at offset zero.
typename or
template template parameters can be mangled incorrectly.
template <typename Q>
void f(typename Q::X) {}
template <template <typename> class Q>
void f(typename Q<int>::X) {}
Instantiations of these templates may be mangled incorrectly.
It also warns psABI related changes. The known psABI changes at this point include:
union U {
long double ld;
int i;
};
union U will always be passed in memory.
-Wctor-dtor-privacy (C++ and Objective-C++ only)-Wdelete-non-virtual-dtor (C++ and Objective-C++ only)-Wnarrowing (C++ and Objective-C++ only) int i = { 2.2 }; // error: narrowing from double to int
This flag is included in -Wall and -Wc++11-compat.
With -std=c++11, -Wno-narrowing suppresses the diagnostic
required by the standard. Note that this does not affect the meaning
of well-formed code; narrowing conversions are still considered
ill-formed in SFINAE context.
-Wnoexcept (C++ and Objective-C++ only)-Wnon-virtual-dtor (C++ and Objective-C++ only)-Wreorder (C++ and Objective-C++ only) struct A {
int i;
int j;
A(): j (0), i (1) { }
};
The compiler will rearrange the member initializers for ‘i’ and ‘j’ to match the declaration order of the members, emitting a warning to that effect. This warning is enabled by -Wall.
The following -W... options are not affected by -Wall.
-Weffc++ (C++ and Objective-C++ only)operator= return a reference to *this.
Also warn about violations of the following style guidelines from Scott Meyers' More Effective C++ book:
&&, ||, or ,.
When selecting this option, be aware that the standard library
headers do not obey all of these guidelines; use ‘grep -v’
to filter out those warnings.
-Wstrict-null-sentinel (C++ and Objective-C++ only)NULL as sentinel. When
compiling only with GCC this is a valid sentinel, as NULL is defined
to __null. Although it is a null pointer constant not a null pointer,
it is guaranteed to be of the same size as a pointer. But this use is
not portable across different compilers.
-Wno-non-template-friend (C++ and Objective-C++ only)-Wold-style-cast (C++ and Objective-C++ only)-Woverloaded-virtual (C++ and Objective-C++ only) struct A {
virtual void f();
};
struct B: public A {
void f(int);
};
the A class version of f is hidden in B, and code
like:
B* b;
b->f();
will fail to compile.
-Wno-pmf-conversions (C++ and Objective-C++ only)-Wsign-promo (C++ and Objective-C++ only) struct A {
operator int ();
A& operator = (int);
};
main ()
{
A a,b;
a = b;
}
In this example, G++ will synthesize a default ‘A& operator = (const A&);’, while cfront will use the user-defined ‘operator =’.
(NOTE: This manual does not describe the Objective-C and Objective-C++ languages themselves. See Language Standards Supported by GCC, for references.)
This section describes the command-line options that are only meaningful
for Objective-C and Objective-C++ programs, but you can also use most of
the language-independent GNU compiler options.
For example, you might compile a file some_class.m like this:
gcc -g -fgnu-runtime -O -c some_class.m
In this example, -fgnu-runtime is an option meant only for Objective-C and Objective-C++ programs; you can use the other options with any language supported by GCC.
Note that since Objective-C is an extension of the C language, Objective-C compilations may also use options specific to the C front-end (e.g., -Wtraditional). Similarly, Objective-C++ compilations may use C++-specific options (e.g., -Wabi).
Here is a list of options that are only for compiling Objective-C and Objective-C++ programs:
-fconstant-string-class=class-name@"...". The default
class name is NXConstantString if the GNU runtime is being used, and
NSConstantString if the NeXT runtime is being used (see below). The
-fconstant-cfstrings option, if also present, will override the
-fconstant-string-class setting and cause @"..." literals
to be laid out as constant CoreFoundation strings.
-fgnu-runtime-fnext-runtime__NEXT_RUNTIME__ is predefined if (and only if) this option is
used.
-fno-nil-receivers[receiver
message:arg]) in this translation unit ensure that the receiver is
not nil. This allows for more efficient entry points in the
runtime to be used. This option is only available in conjunction with
the NeXT runtime and ABI version 0 or 1.
-fobjc-abi-version=n-fobjc-call-cxx-cdtors- (id) .cxx_construct instance method which will run
non-trivial default constructors on any such instance variables, in order,
and then return self. Similarly, check if any instance variable
is a C++ object with a non-trivial destructor, and if so, synthesize a
special - (void) .cxx_destruct method which will run
all such default destructors, in reverse order.
The - (id) .cxx_construct and - (void) .cxx_destruct
methods thusly generated will only operate on instance variables
declared in the current Objective-C class, and not those inherited
from superclasses. It is the responsibility of the Objective-C
runtime to invoke all such methods in an object's inheritance
hierarchy. The - (id) .cxx_construct methods will be invoked
by the runtime immediately after a new object instance is allocated;
the - (void) .cxx_destruct methods will be invoked immediately
before the runtime deallocates an object instance.
As of this writing, only the NeXT runtime on Mac OS X 10.4 and later has
support for invoking the - (id) .cxx_construct and
- (void) .cxx_destruct methods.
-fobjc-direct-dispatch-fobjc-exceptions@try,
@throw, @catch, @finally and
@synchronized. This option is available with both the GNU
runtime and the NeXT runtime (but not available in conjunction with
the NeXT runtime on Mac OS X 10.2 and earlier).
-fobjc-gc-fobjc-nilcheck-fobjc-std=objc1-freplace-objc-classes-fzero-linkobjc_getClass("...") (when the name of the class is known at
compile time) with static class references that get initialized at load time,
which improves run-time performance. Specifying the -fzero-link flag
suppresses this behavior and causes calls to objc_getClass("...")
to be retained. This is useful in Zero-Link debugging mode, since it allows
for individual class implementations to be modified during program execution.
The GNU runtime currently always retains calls to objc_get_class("...")
regardless of command-line options.
-gen-decls-Wassign-intercept (Objective-C and Objective-C++ only)-Wno-protocol (Objective-C and Objective-C++ only)-Wselector (Objective-C and Objective-C++ only)@selector(...)
expression, and a corresponding method for that selector has been found
during compilation. Because these checks scan the method table only at
the end of compilation, these warnings are not produced if the final
stage of compilation is not reached, for example because an error is
found during compilation, or because the -fsyntax-only option is
being used.
-Wstrict-selector-match (Objective-C and Objective-C++ only)id or Class. When this flag
is off (which is the default behavior), the compiler will omit such warnings
if any differences found are confined to types that share the same size
and alignment.
-Wundeclared-selector (Objective-C and Objective-C++ only)@selector(...) expression referring to an
undeclared selector is found. A selector is considered undeclared if no
method with that name has been declared before the
@selector(...) expression, either explicitly in an
@interface or @protocol declaration, or implicitly in
an @implementation section. This option always performs its
checks as soon as a @selector(...) expression is found,
while -Wselector only performs its checks in the final stage of
compilation. This also enforces the coding style convention
that methods and selectors must be declared before being used.
-print-objc-runtime-infoTraditionally, diagnostic messages have been formatted irrespective of the output device's aspect (e.g. its width, ...). The options described below can be used to control the diagnostic messages formatting algorithm, e.g. how many characters per line, how often source location information should be reported. Right now, only the C++ front end can honor these options. However it is expected, in the near future, that the remaining front ends would be able to digest them correctly.
-fmessage-length=n-fdiagnostics-show-location=once-fdiagnostics-show-location=every-line-fno-diagnostics-show-optionWarnings are diagnostic messages that report constructions that are not inherently erroneous but that are risky or suggest there may have been an error.
The following language-independent options do not enable specific warnings but control the kinds of diagnostics produced by GCC.
-fsyntax-only-fmax-errors=n-w-Werror-Werror=The warning message for each controllable warning includes the option that controls the warning. That option can then be used with -Werror= and -Wno-error= as described above. (Printing of the option in the warning message can be disabled using the -fno-diagnostics-show-option flag.)
Note that specifying -Werror=foo automatically implies
-Wfoo. However, -Wno-error=foo does not
imply anything.
-Wfatal-errorsYou can request many specific warnings with options beginning ‘-W’, for example -Wimplicit to request warnings on implicit declarations. Each of these specific warning options also has a negative form beginning ‘-Wno-’ to turn off warnings; for example, -Wno-implicit. This manual lists only one of the two forms, whichever is not the default. For further, language-specific options also refer to C++ Dialect Options and Objective-C and Objective-C++ Dialect Options.
When an unrecognized warning option is requested (e.g., -Wunknown-warning), GCC will emit a diagnostic stating that the option is not recognized. However, if the -Wno- form is used, the behavior is slightly different: No diagnostic will be produced for -Wno-unknown-warning unless other diagnostics are being produced. This allows the use of new -Wno- options with old compilers, but if something goes wrong, the compiler will warn that an unrecognized option was used.
-pedanticValid ISO C and ISO C++ programs should compile properly with or without this option (though a rare few will require -ansi or a -std option specifying the required version of ISO C). However, without this option, certain GNU extensions and traditional C and C++ features are supported as well. With this option, they are rejected.
-pedantic does not cause warning messages for use of the
alternate keywords whose names begin and end with ‘__’. Pedantic
warnings are also disabled in the expression that follows
__extension__. However, only system header files should use
these escape routes; application programs should avoid them.
See Alternate Keywords.
Some users try to use -pedantic to check programs for strict ISO C conformance. They soon find that it does not do quite what they want: it finds some non-ISO practices, but not all—only those for which ISO C requires a diagnostic, and some others for which diagnostics have been added.
A feature to report any failure to conform to ISO C might be useful in some instances, but would require considerable additional work and would be quite different from -pedantic. We don't have plans to support such a feature in the near future.
Where the standard specified with -std represents a GNU
extended dialect of C, such as ‘gnu90’ or ‘gnu99’, there is a
corresponding base standard, the version of ISO C on which the GNU
extended dialect is based. Warnings from -pedantic are given
where they are required by the base standard. (It would not make sense
for such warnings to be given only for features not in the specified GNU
C dialect, since by definition the GNU dialects of C include all
features the compiler supports with the given option, and there would be
nothing to warn about.)
-pedantic-errors-Wall-Wall turns on the following warning flags:
-Waddress
-Warray-bounds (only with -O2)
-Wc++11-compat
-Wchar-subscripts
-Wenum-compare (in C/Objc; this is on by default in C++)
-Wimplicit-int (C and Objective-C only)
-Wimplicit-function-declaration (C and Objective-C only)
-Wcomment
-Wformat
-Wmain (only for C/ObjC and unless -ffreestanding)
-Wmaybe-uninitialized
-Wmissing-braces
-Wnonnull
-Wparentheses
-Wpointer-sign
-Wreorder
-Wreturn-type
-Wsequence-point
-Wsign-compare (only in C++)
-Wstrict-aliasing
-Wstrict-overflow=1
-Wswitch
-Wtrigraphs
-Wuninitialized
-Wunknown-pragmas
-Wunused-function
-Wunused-label
-Wunused-value
-Wunused-variable
-Wvolatile-register-var
Note that some warning flags are not implied by -Wall. Some of
them warn about constructions that users generally do not consider
questionable, but which occasionally you might wish to check for;
others warn about constructions that are necessary or hard to avoid in
some cases, and there is no simple way to modify the code to suppress
the warning. Some of them are enabled by -Wextra but many of
them must be enabled individually.
-Wextra -Wclobbered
-Wempty-body
-Wignored-qualifiers
-Wmissing-field-initializers
-Wmissing-parameter-type (C only)
-Wold-style-declaration (C only)
-Woverride-init
-Wsign-compare
-Wtype-limits
-Wuninitialized
-Wunused-parameter (only with -Wunused or -Wall)
-Wunused-but-set-parameter (only with -Wunused or -Wall)
The option -Wextra also prints warning messages for the following cases:
-Wchar-subscriptschar. This is a common cause
of error, as programmers often forget that this type is signed on some
machines.
This warning is enabled by -Wall.
-Wcomment-Wno-coverage-mismatch-Wno-cppSuppress warning messages emitted by #warning directives.
-Wdouble-promotion (C, C++, Objective-C and Objective-C++ only)float is implicitly
promoted to double. CPUs with a 32-bit “single-precision”
floating-point unit implement float in hardware, but emulate
double in software. On such a machine, doing computations
using double values is much more expensive because of the
overhead required for software emulation.
It is easy to accidentally do computations with double because
floating-point literals are implicitly of type double. For
example, in:
float area(float radius)
{
return 3.14159 * radius * radius;
}
the compiler will perform the entire computation with double
because the floating-point literal is a double.
-Wformatprintf and scanf, etc., to make sure that
the arguments supplied have types appropriate to the format string
specified, and that the conversions specified in the format string make
sense. This includes standard functions, and others specified by format
attributes (see Function Attributes), in the printf,
scanf, strftime and strfmon (an X/Open extension,
not in the C standard) families (or other target-specific families).
Which functions are checked without format attributes having been
specified depends on the standard version selected, and such checks of
functions without the attribute specified are disabled by
-ffreestanding or -fno-builtin.
The formats are checked against the format features supported by GNU
libc version 2.2. These include all ISO C90 and C99 features, as well
as features from the Single Unix Specification and some BSD and GNU
extensions. Other library implementations may not support all these
features; GCC does not support warning about features that go beyond a
particular library's limitations. However, if -pedantic is used
with -Wformat, warnings will be given about format features not
in the selected standard version (but not for strfmon formats,
since those are not in any version of the C standard). See Options Controlling C Dialect.
Since -Wformat also checks for null format arguments for several functions, -Wformat also implies -Wnonnull.
-Wformat is included in -Wall. For more control over some
aspects of format checking, the options -Wformat-y2k,
-Wno-format-extra-args, -Wno-format-zero-length,
-Wformat-nonliteral, -Wformat-security, and
-Wformat=2 are available, but are not included in -Wall.
-Wformat-y2kstrftime
formats that may yield only a two-digit year.
-Wno-format-contains-nul-Wno-format-extra-argsprintf or scanf format function. The C standard specifies
that such arguments are ignored.
Where the unused arguments lie between used arguments that are
specified with ‘$’ operand number specifications, normally
warnings are still given, since the implementation could not know what
type to pass to va_arg to skip the unused arguments. However,
in the case of scanf formats, this option will suppress the
warning if the unused arguments are all pointers, since the Single
Unix Specification says that such unused arguments are allowed.
-Wno-format-zero-length-Wformat-nonliteralva_list.
-Wformat-securityprintf and scanf functions where the
format string is not a string literal and there are no format arguments,
as in printf (foo);. This may be a security hole if the format
string came from untrusted input and contains ‘%n’. (This is
currently a subset of what -Wformat-nonliteral warns about, but
in future warnings may be added to -Wformat-security that are not
included in -Wformat-nonliteral.)
-Wformat=2-Wnonnullnonnull function attribute.
-Wnonnull is included in -Wall and -Wformat. It
can be disabled with the -Wno-nonnull option.
-Winit-self (C, C++, Objective-C and Objective-C++ only)For example, GCC will warn about i being uninitialized in the
following snippet only when -Winit-self has been specified:
int f()
{
int i = i;
return i;
}
-Wimplicit-int (C and Objective-C only)-Wimplicit-function-declaration (C and Objective-C only)-Wimplicit (C and Objective-C only)-Wignored-qualifiers (C and C++ only)const. For ISO C such a type qualifier has no effect,
since the value returned by a function is not an lvalue.
For C++, the warning is only emitted for scalar types or void.
ISO C prohibits qualified void return types on function
definitions, so such return types always receive a warning
even without this option.
This warning is also enabled by -Wextra.
-Wmain-Wmissing-braces int a[2][2] = { 0, 1, 2, 3 };
int b[2][2] = { { 0, 1 }, { 2, 3 } };
This warning is enabled by -Wall.
-Wmissing-include-dirs (C, C++, Objective-C and Objective-C++ only)-WparenthesesAlso warn if a comparison like ‘x<=y<=z’ appears; this is equivalent to ‘(x<=y ? 1 : 0) <= z’, which is a different interpretation from that of ordinary mathematical notation.
Also warn about constructions where there may be confusion to which
if statement an else branch belongs. Here is an example of
such a case:
{
if (a)
if (b)
foo ();
else
bar ();
}
In C/C++, every else branch belongs to the innermost possible
if statement, which in this example is if (b). This is
often not what the programmer expected, as illustrated in the above
example by indentation the programmer chose. When there is the
potential for this confusion, GCC will issue a warning when this flag
is specified. To eliminate the warning, add explicit braces around
the innermost if statement so there is no way the else
could belong to the enclosing if. The resulting code would
look like this:
{
if (a)
{
if (b)
foo ();
else
bar ();
}
}
Also warn for dangerous uses of the ?: with omitted middle operand GNU extension. When the condition in the ?: operator is a boolean expression the omitted value will be always 1. Often the user expects it to be a value computed inside the conditional expression instead.
This warning is enabled by -Wall.
-Wsequence-pointThe C and C++ standards defines the order in which expressions in a C/C++
program are evaluated in terms of sequence points, which represent
a partial ordering between the execution of parts of the program: those
executed before the sequence point, and those executed after it. These
occur after the evaluation of a full expression (one which is not part
of a larger expression), after the evaluation of the first operand of a
&&, ||, ? : or , (comma) operator, before a
function is called (but after the evaluation of its arguments and the
expression denoting the called function), and in certain other places.
Other than as expressed by the sequence point rules, the order of
evaluation of subexpressions of an expression is not specified. All
these rules describe only a partial order rather than a total order,
since, for example, if two functions are called within one expression
with no sequence point between them, the order in which the functions
are called is not specified. However, the standards committee have
ruled that function calls do not overlap.
It is not specified when between sequence points modifications to the values of objects take effect. Programs whose behavior depends on this have undefined behavior; the C and C++ standards specify that “Between the previous and next sequence point an object shall have its stored value modified at most once by the evaluation of an expression. Furthermore, the prior value shall be read only to determine the value to be stored.”. If a program breaks these rules, the results on any particular implementation are entirely unpredictable.
Examples of code with undefined behavior are a = a++;, a[n]
= b[n++] and a[i++] = i;. Some more complicated cases are not
diagnosed by this option, and it may give an occasional false positive
result, but in general it has been found fairly effective at detecting
this sort of problem in programs.
The standard is worded confusingly, therefore there is some debate over the precise meaning of the sequence point rules in subtle cases. Links to discussions of the problem, including proposed formal definitions, may be found on the GCC readings page, at http://gcc.gnu.org/readings.html.
This warning is enabled by -Wall for C and C++.
-Wreturn-typeint. Also warn about any return statement with no
return-value in a function whose return-type is not void
(falling off the end of the function body is considered returning
without a value), and about a return statement with an
expression in a function whose return-type is void.
For C++, a function without return type always produces a diagnostic message, even when -Wno-return-type is specified. The only exceptions are ‘main’ and functions defined in system headers.
This warning is enabled by -Wall.
-Wswitchswitch statement has an index of enumerated type
and lacks a case for one or more of the named codes of that
enumeration. (The presence of a default label prevents this
warning.) case labels outside the enumeration range also
provoke warnings when this option is used (even if there is a
default label).
This warning is enabled by -Wall.
-Wswitch-defaultswitch statement does not have a default
case.
-Wswitch-enumswitch statement has an index of enumerated type
and lacks a case for one or more of the named codes of that
enumeration. case labels outside the enumeration range also
provoke warnings when this option is used. The only difference
between -Wswitch and this option is that this option gives a
warning about an omitted enumeration code even if there is a
default label.
-Wsync-nand (C and C++ only)__sync_fetch_and_nand and __sync_nand_and_fetch
built-in functions are used. These functions changed semantics in GCC 4.4.
-Wtrigraphs-Wunused-but-set-parameterTo suppress this warning use the ‘unused’ attribute (see Variable Attributes).
This warning is also enabled by -Wunused together with
-Wextra.
-Wunused-but-set-variableTo suppress this warning use the ‘unused’ attribute (see Variable Attributes).
This warning is also enabled by -Wunused, which is enabled
by -Wall.
-Wunused-function-Wunused-labelTo suppress this warning use the ‘unused’ attribute
(see Variable Attributes).
-Wunused-local-typedefs (C, Objective-C, C++ and Objective-C++ only)-Wunused-parameterTo suppress this warning use the ‘unused’ attribute
(see Variable Attributes).
-Wno-unused-resultwarn_unused_result (see Function Attributes) does not use
its return value. The default is -Wunused-result.
-Wunused-variableTo suppress this warning use the ‘unused’ attribute
(see Variable Attributes).
-Wunused-valueThis warning is enabled by -Wall.
-WunusedIn order to get a warning about an unused function parameter, you must
either specify ‘-Wextra -Wunused’ (note that ‘-Wall’ implies
‘-Wunused’), or separately specify -Wunused-parameter.
-Wuninitializedsetjmp call. In C++,
warn if a non-static reference or non-static ‘const’ member
appears in a class without constructors.
If you want to warn about code that uses the uninitialized value of the variable in its own initializer, use the -Winit-self option.
These warnings occur for individual uninitialized or clobbered
elements of structure, union or array variables as well as for
variables that are uninitialized or clobbered as a whole. They do
not occur for variables or elements declared volatile. Because
these warnings depend on optimization, the exact variables or elements
for which there are warnings will depend on the precise optimization
options and version of GCC used.
Note that there may be no warning about a variable that is used only
to compute a value that itself is never used, because such
computations may be deleted by data flow analysis before the warnings
are printed.
-Wmaybe-uninitialized {
int x;
switch (y)
{
case 1: x = 1;
break;
case 2: x = 4;
break;
case 3: x = 5;
}
foo (x);
}
If the value of y is always 1, 2 or 3, then x is
always initialized, but GCC doesn't know this. To suppress the
warning, the user needs to provide a default case with assert(0) or
similar code.
This option also warns when a non-volatile automatic variable might be
changed by a call to longjmp. These warnings as well are possible
only in optimizing compilation.
The compiler sees only the calls to setjmp. It cannot know
where longjmp will be called; in fact, a signal handler could
call it at any point in the code. As a result, you may get a warning
even when there is in fact no problem because longjmp cannot
in fact be called at the place that would cause a problem.
Some spurious warnings can be avoided if you declare all the functions
you use that never return as noreturn. See Function Attributes.
This warning is enabled by -Wall or -Wextra.
-Wunknown-pragmas#pragma directive is encountered that is not understood by
GCC. If this command-line option is used, warnings will even be issued
for unknown pragmas in system header files. This is not the case if
the warnings were only enabled by the -Wall command-line option.
-Wno-pragmas-Wstrict-aliasing-Wstrict-aliasing=nLevel 1: Most aggressive, quick, least accurate. Possibly useful when higher levels do not warn but -fstrict-aliasing still breaks the code, as it has very few false negatives. However, it has many false positives. Warns for all pointer conversions between possibly incompatible types, even if never dereferenced. Runs in the front end only.
Level 2: Aggressive, quick, not too precise. May still have many false positives (not as many as level 1 though), and few false negatives (but possibly more than level 1). Unlike level 1, it only warns when an address is taken. Warns about incomplete types. Runs in the front end only.
Level 3 (default for -Wstrict-aliasing):
Should have very few false positives and few false
negatives. Slightly slower than levels 1 or 2 when optimization is enabled.
Takes care of the common pun+dereference pattern in the front end:
*(int*)&some_float.
If optimization is enabled, it also runs in the back end, where it deals
with multiple statement cases using flow-sensitive points-to information.
Only warns when the converted pointer is dereferenced.
Does not warn about incomplete types.
-Wstrict-overflow-Wstrict-overflow=nAn optimization that assumes that signed overflow does not occur is perfectly safe if the values of the variables involved are such that overflow never does, in fact, occur. Therefore this warning can easily give a false positive: a warning about code that is not actually a problem. To help focus on important issues, several warning levels are defined. No warnings are issued for the use of undefined signed overflow when estimating how many iterations a loop will require, in particular when determining whether a loop will be executed at all.
-Wstrict-overflow=1x + 1 > x; with -fstrict-overflow, the
compiler will simplify this to 1. This level of
-Wstrict-overflow is enabled by -Wall; higher levels
are not, and must be explicitly requested.
-Wstrict-overflow=2abs (x) >= 0. This can only be
simplified when -fstrict-overflow is in effect, because
abs (INT_MIN) overflows to INT_MIN, which is less than
zero. -Wstrict-overflow (with no level) is the same as
-Wstrict-overflow=2.
-Wstrict-overflow=3x + 1 > 1 will be simplified to x > 0.
-Wstrict-overflow=4(x * 10) / 5 will be simplified to x * 2.
-Wstrict-overflow=5x + 2 > y will
be simplified to x + 1 >= y. This is reported only at the
highest warning level because this simplification applies to many
comparisons, so this warning level will give a very large number of
false positives.
-Wsuggest-attribute=[pure|const|noreturn]-Wsuggest-attribute=pure-Wsuggest-attribute=const-Wsuggest-attribute=noreturnpure, const or noreturn. The compiler only warns for
functions visible in other compilation units or (in the case of pure and
const) if it cannot prove that the function returns normally. A function
returns normally if it doesn't contain an infinite loop nor returns abnormally
by throwing, calling abort() or trapping. This analysis requires option
-fipa-pure-const, which is enabled by default at -O and
higher. Higher optimization levels improve the accuracy of the analysis.
-Warray-bounds-Wno-div-by-zero-Wsystem-headers-WtrampolinesA trampoline is a small piece of data or code that is created at run
time on the stack when the address of a nested function is taken, and
is used to call the nested function indirectly. For some targets, it
is made up of data only and thus requires no special treatment. But,
for most targets, it is made up of code and thus requires the stack
to be made executable in order for the program to work properly.
-Wfloat-equalThe idea behind this is that sometimes it is convenient (for the
programmer) to consider floating-point values as approximations to
infinitely precise real numbers. If you are doing this, then you need
to compute (by analyzing the code, or in some other way) the maximum or
likely maximum error that the computation introduces, and allow for it
when performing comparisons (and when producing output, but that's a
different problem). In particular, instead of testing for equality, you
would check to see whether the two values have ranges that overlap; and
this is done with the relational operators, so equality comparisons are
probably mistaken.
-Wtraditional (C and Objective-C only)<limits.h>.
Use of these macros in user code might normally lead to spurious
warnings, however GCC's integrated preprocessor has enough context to
avoid warning in these cases.
switch statement has an operand of type long.
static function declaration follows a static one.
This construct is not accepted by some traditional C compilers.
__STDC__ to avoid missing
initializer warnings and relies on default initialization to zero in the
traditional C case.
PARAMS and
VPARAMS. This warning is also bypassed for nested functions
because that feature is already a GCC extension and thus not relevant to
traditional C compatibility.
-Wtraditional-conversion (C and Objective-C only)-Wdeclaration-after-statement (C and Objective-C only)-Wundef-Wno-endif-labels-Wshadow-Wlarger-than=len-Wframe-larger-than=lenalloca, variable-length arrays, or related constructs
is not included by the compiler when determining
whether or not to issue a warning.
-Wno-free-nonheap-object-Wstack-usage=lenalloca, variable-length arrays, or related
constructs is included by the compiler when determining whether or not to
issue a warning.
The message is in keeping with the output of -fstack-usage.
warning: stack usage is 1120 bytes
warning: stack usage might be 1648 bytes
warning: stack usage might be unbounded
-Wunsafe-loop-optimizations-Wno-pedantic-ms-format (MinGW targets only)printf / scanf format
width specifiers I32, I64, and I used on Windows targets
depending on the MS runtime, when you are using the options -Wformat
and -pedantic without gnu-extensions.
-Wpointer-arithvoid. GNU C assigns these types a size of 1, for
convenience in calculations with void * pointers and pointers
to functions. In C++, warn also when an arithmetic operation involves
NULL. This warning is also enabled by -pedantic.
-Wtype-limits-Wbad-function-cast (C and Objective-C only)int malloc() is cast to anything *.
-Wc++-compat (C and Objective-C only)void * to a pointer to non-void type.
-Wc++11-compat (C++ and Objective-C++ only)-Wcast-qualconst char * is cast
to an ordinary char *.
Also warn when making a cast that introduces a type qualifier in an
unsafe way. For example, casting char ** to const char **
is unsafe, as in this example:
/* p is char ** value. */
const char **q = (const char **) p;
/* Assignment of readonly string to const char * is OK. */
*q = "string";
/* Now char** pointer points to read-only memory. */
**p = 'b';
-Wcast-alignchar * is cast to
an int * on machines where integers can only be accessed at
two- or four-byte boundaries.
-Wwrite-stringsconst
char[length] so that copying the address of one into a
non-const char * pointer will get a warning. These
warnings will help you find at compile time code that can try to write
into a string constant, but only if you have been very careful about
using const in declarations and prototypes. Otherwise, it will
just be a nuisance. This is why we did not make -Wall request
these warnings.
When compiling C++, warn about the deprecated conversion from string
literals to char *. This warning is enabled by default for C++
programs.
-Wclobbered-Wconversionabs (x) when
x is double; conversions between signed and unsigned,
like unsigned ui = -1; and conversions to smaller types, like
sqrtf (M_PI). Do not warn for explicit casts like abs
((int) x) and ui = (unsigned) -1, or if the value is not
changed by the conversion like in abs (2.0). Warnings about
conversions between signed and unsigned integers can be disabled by
using -Wno-sign-conversion.
For C++, also warn for confusing overload resolution for user-defined
conversions; and conversions that will never use a type conversion
operator: conversions to void, the same type, a base class or a
reference to them. Warnings about conversions between signed and
unsigned integers are disabled by default in C++ unless
-Wsign-conversion is explicitly enabled.
-Wno-conversion-null (C++ and Objective-C++ only)NULL and non-pointer
types. -Wconversion-null is enabled by default.
-Wzero-as-null-pointer-constant (C++ and Objective-C++ only)nullptr in C++11.
-Wempty-body-Wenum-compare-Wjump-misses-init (C, Objective-C only)goto statement or a switch statement jumps
forward across the initialization of a variable, or jumps backward to a
label after the variable has been initialized. This only warns about
variables that are initialized when they are declared. This warning is
only supported for C and Objective-C; in C++ this sort of branch is an
error in any case.
-Wjump-misses-init is included in -Wc++-compat. It
can be disabled with the -Wno-jump-misses-init option.
-Wsign-compare-Wsign-conversion-Waddressvoid func(void); if (func), and comparisons against the memory
address of a string literal, such as if (x == "abc"). Such
uses typically indicate a programmer error: the address of a function
always evaluates to true, so their use in a conditional usually
indicate that the programmer forgot the parentheses in a function
call; and comparisons against string literals result in unspecified
behavior and are not portable in C, so they usually indicate that the
programmer intended to use strcmp. This warning is enabled by
-Wall.
-Wlogical-op-Waggregate-return-Wno-attributes__attribute__ is used, such as
unrecognized attributes, function attributes applied to variables,
etc. This will not stop errors for incorrect use of supported
attributes.
-Wno-builtin-macro-redefined__TIMESTAMP__, __TIME__,
__DATE__, __FILE__, and __BASE_FILE__.
-Wstrict-prototypes (C and Objective-C only)-Wold-style-declaration (C and Objective-C only)static are not the first things in a declaration. This warning
is also enabled by -Wextra.
-Wold-style-definition (C and Objective-C only)-Wmissing-parameter-type (C and Objective-C only) void foo(bar) { }
This warning is also enabled by -Wextra.
-Wmissing-prototypes (C and Objective-C only)-Wmissing-declarations-Wmissing-field-initializersx.h is implicitly zero:
struct s { int f, g, h; };
struct s x = { 3, 4 };
This option does not warn about designated initializers, so the following modification would not trigger a warning:
struct s { int f, g, h; };
struct s x = { .f = 3, .g = 4 };
This warning is included in -Wextra. To get other -Wextra
warnings without this one, use ‘-Wextra -Wno-missing-field-initializers’.
-Wmissing-format-attributeformat
attributes. Note these are only possible candidates, not absolute ones.
GCC will guess that function pointers with format attributes that
are used in assignment, initialization, parameter passing or return
statements should have a corresponding format attribute in the
resulting type. I.e. the left-hand side of the assignment or
initialization, the type of the parameter variable, or the return type
of the containing function respectively should also have a format
attribute to avoid the warning.
GCC will also warn about function definitions that might be
candidates for format attributes. Again, these are only
possible candidates. GCC will guess that format attributes
might be appropriate for any function that calls a function like
vprintf or vscanf, but this might not always be the
case, and some functions for which format attributes are
appropriate may not be detected.
-Wno-multichar-Wnormalized=<none|id|nfc|nfkc>There are four levels of warning supported by GCC. The default is -Wnormalized=nfc, which warns about any identifier that is not in the ISO 10646 “C” normalized form, NFC. NFC is the recommended form for most uses.
Unfortunately, there are some characters allowed in identifiers by ISO C and ISO C++ that, when turned into NFC, are not allowed in identifiers. That is, there's no way to use these symbols in portable ISO C or C++ and have all your identifiers in NFC. -Wnormalized=id suppresses the warning for these characters. It is hoped that future versions of the standards involved will correct this, which is why this option is not the default.
You can switch the warning off for all characters by writing -Wnormalized=none. You would only want to do this if you were using some other normalization scheme (like “D”), because otherwise you can easily create bugs that are literally impossible to see.
Some characters in ISO 10646 have distinct meanings but look identical
in some fonts or display methodologies, especially once formatting has
been applied. For instance \u207F, “SUPERSCRIPT LATIN SMALL
LETTER N”, will display just like a regular n that has been
placed in a superscript. ISO 10646 defines the NFKC
normalization scheme to convert all these into a standard form as
well, and GCC will warn if your code is not in NFKC if you use
-Wnormalized=nfkc. This warning is comparable to warning
about every identifier that contains the letter O because it might be
confused with the digit 0, and so is not the default, but may be
useful as a local coding convention if the programming environment is
unable to be fixed to display these characters distinctly.
-Wno-deprecated-Wno-deprecated-declarationsdeprecated
attribute.
-Wno-overflow-Woverride-init (C and Objective-C only)This warning is included in -Wextra. To get other
-Wextra warnings without this one, use ‘-Wextra
-Wno-override-init’.
-Wpackedf.x in struct bar
will be misaligned even though struct bar does not itself
have the packed attribute:
struct foo {
int x;
char a, b, c, d;
} __attribute__((packed));
struct bar {
char z;
struct foo f;
};
-Wpacked-bitfield-compatpacked attribute
on bit-fields of type char. This has been fixed in GCC 4.4 but
the change can lead to differences in the structure layout. GCC
informs you when the offset of such a field has changed in GCC 4.4.
For example there is no longer a 4-bit padding between field a
and b in this structure:
struct foo
{
char a:4;
char b:8;
} __attribute__ ((packed));
This warning is enabled by default. Use
-Wno-packed-bitfield-compat to disable this warning.
-Wpadded-Wredundant-decls-Wnested-externs (C and Objective-C only)extern declaration is encountered within a function.
-WinlineThe compiler uses a variety of heuristics to determine whether or not
to inline a function. For example, the compiler takes into account
the size of the function being inlined and the amount of inlining
that has already been done in the current function. Therefore,
seemingly insignificant changes in the source program can cause the
warnings produced by -Winline to appear or disappear.
-Wno-invalid-offsetof (C++ and Objective-C++ only)The restrictions on ‘offsetof’ may be relaxed in a future version
of the C++ standard.
-Wno-int-to-pointer-cast-Wno-pointer-to-int-cast (C and Objective-C only)-Winvalid-pch-Wlong-long-Wvariadic-macros-Wvector-operation-performancepiecewise, which means that the
scalar operation is performed on every vector element;
in parallel, which means that the vector operation is implemented
using scalars of wider type, which normally is more performance efficient;
and as a single scalar, which means that vector fits into a
scalar type.
-Wvla-Wvolatile-register-var-Wdisabled-optimization-Wpointer-sign (C and Objective-C only)-Wstack-protector-Wno-mudflap-Woverlength-stringsThe limit applies after string constant concatenation, and does not count the trailing NUL. In C90, the limit was 509 characters; in C99, it was raised to 4095. C++98 does not specify a normative minimum maximum, so we do not diagnose overlength strings in C++.
This option is implied by -pedantic, and can be disabled with
-Wno-overlength-strings.
-Wunsuffixed-float-constants (C and Objective-C only)FLOAT_CONST_DECIMAL64 pragma
from the decimal floating-point extension to C99.
GCC has various special options that are used for debugging either your program or GCC:
-gOn most systems that use stabs format, -g enables use of extra debugging information that only GDB can use; this extra information makes debugging work better in GDB but will probably make other debuggers crash or refuse to read the program. If you want to control for certain whether to generate the extra information, use -gstabs+, -gstabs, -gxcoff+, -gxcoff, or -gvms (see below).
GCC allows you to use -g with -O. The shortcuts taken by optimized code may occasionally produce surprising results: some variables you declared may not exist at all; flow of control may briefly move where you did not expect it; some statements may not be executed because they compute constant results or their values were already at hand; some statements may execute in different places because they were moved out of loops.
Nevertheless it proves possible to debug optimized output. This makes it reasonable to use the optimizer for programs that might have bugs.
The following options are useful when GCC is generated with the
capability for more than one debugging format.
-ggdb-gstabs-feliminate-unused-debug-symbols-femit-class-debug-always-fno-debug-types-section-gstabs+-gcoff-gxcoff-gxcoff+-gdwarf-versionNote that with DWARF version 2 some ports require, and will always use, some non-conflicting DWARF 3 extensions in the unwind tables.
Version 4 may require GDB 7.0 and -fvar-tracking-assignments
for maximum benefit.
-grecord-gcc-switches-gno-record-gcc-switches-gstrict-dwarf-gno-strict-dwarf-gvms-glevel-ggdblevel-gstabslevel-gcofflevel-gxcofflevel-gvmslevelLevel 0 produces no debug information at all. Thus, -g0 negates -g.
Level 1 produces minimal information, enough for making backtraces in parts of the program that you don't plan to debug. This includes descriptions of functions and external variables, but no information about local variables and no line numbers.
Level 3 includes extra information, such as all the macro definitions present in the program. Some debuggers support macro expansion when you use -g3.
-gdwarf-2 does not accept a concatenated debug level, because
GCC used to support an option -gdwarf that meant to generate
debug information in version 1 of the DWARF format (which is very
different from version 2), and it would have been too confusing. That
debug format is long obsolete, but the option cannot be changed now.
Instead use an additional -glevel option to change the
debug level for DWARF.
-gtoggle-fdump-final-insns[=file].), the name
of the dump file will be determined by appending .gkd to the
compilation output file name.
-fcompare-debug[=opts]If the equal sign is omitted, the default -gtoggle is used.
The environment variable GCC_COMPARE_DEBUG, if defined, non-empty and nonzero, implicitly enables -fcompare-debug. If GCC_COMPARE_DEBUG is defined to a string starting with a dash, then it is used for opts, otherwise the default -gtoggle is used.
-fcompare-debug=, with the equal sign but without opts, is equivalent to -fno-compare-debug, which disables the dumping of the final representation and the second compilation, preventing even GCC_COMPARE_DEBUG from taking effect.
To verify full coverage during -fcompare-debug testing, set
GCC_COMPARE_DEBUG to say ‘-fcompare-debug-not-overridden’,
which GCC will reject as an invalid option in any actual compilation
(rather than preprocessing, assembly or linking). To get just a
warning, setting GCC_COMPARE_DEBUG to ‘-w%n-fcompare-debug
not overridden’ will do.
-fcompare-debug-second.gk additional extension during the second compilation, to avoid
overwriting those generated by the first.
When this option is passed to the compiler driver, it causes the
first compilation to be skipped, which makes it useful for little
other than debugging the compiler proper.
-feliminate-dwarf2-dups-femit-struct-debug-baseonlyThis option substantially reduces the size of debugging information, but at significant potential loss in type information to the debugger. See -femit-struct-debug-reduced for a less aggressive option. See -femit-struct-debug-detailed for more detailed control.
This option works only with DWARF 2.
-femit-struct-debug-reducedThis option significantly reduces the size of debugging information, with some potential loss in type information to the debugger. See -femit-struct-debug-baseonly for a more aggressive option. See -femit-struct-debug-detailed for more detailed control.
This option works only with DWARF 2.
-femit-struct-debug-detailed[=spec-list]This option is a detailed version of -femit-struct-debug-reduced and -femit-struct-debug-baseonly, which will serve for most needs.
A specification has the syntax
[‘dir:’|‘ind:’][‘ord:’|‘gen:’](‘any’|‘sys’|‘base’|‘none’)
The optional first word limits the specification to structs that are used directly (‘dir:’) or used indirectly (‘ind:’). A struct type is used directly when it is the type of a variable, member. Indirect uses arise through pointers to structs. That is, when use of an incomplete struct would be legal, the use is indirect. An example is ‘struct one direct; struct two * indirect;’.
The optional second word limits the specification to ordinary structs (‘ord:’) or generic structs (‘gen:’). Generic structs are a bit complicated to explain. For C++, these are non-explicit specializations of template classes, or non-template classes within the above. Other programming languages have generics, but ‘-femit-struct-debug-detailed’ does not yet implement them.
The third word specifies the source files for those structs for which the compiler will emit debug information. The values ‘none’ and ‘any’ have the normal meaning. The value ‘base’ means that the base of name of the file in which the type declaration appears must match the base of the name of the main compilation file. In practice, this means that types declared in foo.c and foo.h will have debug information, but types declared in other header will not. The value ‘sys’ means those types satisfying ‘base’ or declared in system or compiler headers.
You may need to experiment to determine the best settings for your application.
The default is ‘-femit-struct-debug-detailed=all’.
This option works only with DWARF 2.
-fno-merge-debug-strings-fdebug-prefix-map=old=new-fno-dwarf2-cfi-asm.eh_frame section
instead of using GAS .cfi_* directives.
-p-pg-Q-ftime-report-fmem-report-fpre-ipa-mem-report-fpost-ipa-mem-report-fstack-usagestatic, dynamic, bounded.
The qualifier static means that the function manipulates the stack
statically: a fixed number of bytes are allocated for the frame on function
entry and released on function exit; no stack adjustments are otherwise made
in the function. The second field is this fixed number of bytes.
The qualifier dynamic means that the function manipulates the stack
dynamically: in addition to the static allocation described above, stack
adjustments are made in the body of the function, for example to push/pop
arguments around function calls. If the qualifier bounded is also
present, the amount of these adjustments is bounded at compile time and
the second field is an upper bound of the total amount of stack used by
the function. If it is not present, the amount of these adjustments is
not bounded at compile time and the second field only represents the
bounded part.
-fprofile-arcs--coveragefork calls are detected and correctly handled (double counting
will not happen).
With -fprofile-arcs, for each function of your program GCC
creates a program flow graph, then finds a spanning tree for the graph.
Only arcs that are not on the spanning tree have to be instrumented: the
compiler adds code to count the number of times that these arcs are
executed. When an arc is the only exit or only entrance to a block, the
instrumentation code can be added to the block; otherwise, a new basic
block must be created to hold the instrumentation code.
-ftest-coverage-fdbg-cnt-list-fdbg-cnt=counter-value-list-fenable-kind-pass-fdisable-kind-pass=range-list
# disable ccp1 for all functions
-fdisable-tree-ccp1
# disable complete unroll for function whose cgraph node uid is 1
-fenable-tree-cunroll=1
# disable gcse2 for functions at the following ranges [1,1],
# [300,400], and [400,1000]
# disable gcse2 for functions foo and foo2
-fdisable-rtl-gcse2=foo,foo2
# disable early inlining
-fdisable-tree-einline
# disable ipa inlining
-fdisable-ipa-inline
# enable tree full unroll
-fenable-tree-unroll
-dletters-fdump-rtl-passDebug dumps can be enabled with a -fdump-rtl switch or some -d option letters. Here are the possible letters for use in pass and letters, and their meanings:
-fdump-rtl-alignments-fdump-rtl-asmcons-fdump-rtl-auto_inc_dec-fdump-rtl-barriers-fdump-rtl-bbpart-fdump-rtl-bbro-fdump-rtl-btl1-fdump-rtl-btl2-fdump-rtl-bypass-fdump-rtl-combine-fdump-rtl-compgotos-fdump-rtl-ce1-fdump-rtl-ce2-fdump-rtl-ce3-fdump-rtl-cprop_hardreg-fdump-rtl-csa-fdump-rtl-cse1-fdump-rtl-cse2-fdump-rtl-dce-fdump-rtl-dbr-fdump-rtl-dce1-fdump-rtl-dce2-fdump-rtl-eh-fdump-rtl-eh_ranges-fdump-rtl-expand-fdump-rtl-fwprop1-fdump-rtl-fwprop2-fdump-rtl-gcse1-fdump-rtl-gcse2-fdump-rtl-init-regs-fdump-rtl-initvals-fdump-rtl-into_cfglayout-fdump-rtl-ira-fdump-rtl-jump-fdump-rtl-loop2-fdump-rtl-mach-fdump-rtl-mode_sw-fdump-rtl-rnreg-fdump-rtl-outof_cfglayout-fdump-rtl-peephole2-fdump-rtl-postreload-fdump-rtl-pro_and_epilogue-fdump-rtl-regmove-fdump-rtl-sched1-fdump-rtl-sched2-fdump-rtl-see-fdump-rtl-seqabstr-fdump-rtl-shorten-fdump-rtl-sibling-fdump-rtl-split1-fdump-rtl-split2-fdump-rtl-split3-fdump-rtl-split4-fdump-rtl-split5-fdump-rtl-sms-fdump-rtl-stack-fdump-rtl-subreg1-fdump-rtl-subreg2-fdump-rtl-unshare-fdump-rtl-vartrack-fdump-rtl-vregs-fdump-rtl-web-fdump-rtl-regclass-fdump-rtl-subregs_of_mode_init-fdump-rtl-subregs_of_mode_finish-fdump-rtl-dfinit-fdump-rtl-dfinish-da-fdump-rtl-all-dA-dD-dH-dp-dP-dv-dx-fdump-noaddr-fdump-unnumbered-fdump-unnumbered-links-fdump-translation-unit (C++ only)-fdump-translation-unit-options (C++ only)-fdump-class-hierarchy (C++ only)-fdump-class-hierarchy-options (C++ only)-fdump-ipa-switch-fdump-passes-fdump-statistics-option-fdump-tree-switch-fdump-tree-switch-optionsDECL_ASSEMBLER_NAME has been set for a given decl, use that
in the dump instead of DECL_NAME. Its primary use is ease of
use working backward from mangled names in the assembly file.
DECL_UID) for each variable.
The following tree dumps are possible:
-ftree-vectorizer-verbose=n-frandom-seed=stringThe string should be different for every file you compile.
-fsched-verbose=nFor n greater than zero, -fsched-verbose outputs the
same information as -fdump-rtl-sched1 and -fdump-rtl-sched2.
For n greater than one, it also output basic block probabilities,
detailed ready list information and unit/insn info. For n greater
than two, it includes RTL at abort point, control-flow and regions info.
And for n over four, -fsched-verbose also includes
dependence info.
-save-temps-save-temps=cwdWhen used in combination with the -x command-line option, -save-temps is sensible enough to avoid over writing an input source file with the same extension as an intermediate file. The corresponding intermediate file may be obtained by renaming the source file before using -save-temps.
If you invoke GCC in parallel, compiling several different source files that share a common base name in different subdirectories or the same source file compiled for multiple output destinations, it is likely that the different parallel compilers will interfere with each other, and overwrite the temporary files. For instance:
gcc -save-temps -o outdir1/foo.o indir1/foo.c&
gcc -save-temps -o outdir2/foo.o indir2/foo.c&
may result in foo.i and foo.o being written to
simultaneously by both compilers.
-save-temps=objFor example:
gcc -save-temps=obj -c foo.c
gcc -save-temps=obj -c bar.c -o dir/xbar.o
gcc -save-temps=obj foobar.c -o dir2/yfoobar
would create foo.i, foo.s, dir/xbar.i,
dir/xbar.s, dir2/yfoobar.i, dir2/yfoobar.s, and
dir2/yfoobar.o.
-time[=file]Without the specification of an output file, the output looks like this:
# cc1 0.12 0.01
# as 0.00 0.01
The first number on each line is the “user time”, that is time spent executing the program itself. The second number is “system time”, time spent executing operating system routines on behalf of the program. Both numbers are in seconds.
With the specification of an output file, the output is appended to the named file, and it looks like this:
0.12 0.01 cc1 options
0.00 0.01 as options
The “user time” and the “system time” are moved before the program
name, and the options passed to the program are displayed, so that one
can later tell what file was being compiled, and with which options.
-fvar-trackingIt is enabled by default when compiling with optimization (-Os,
-O, -O2, ...), debugging information (-g) and
the debug info format supports it.
-fvar-tracking-assignmentsIt can be enabled even if var-tracking is disabled, in which case
annotations will be created and maintained, but discarded at the end.
-fvar-tracking-assignments-toggle-print-file-name=library-print-multi-directory-print-multi-lib-print-multi-os-directory-print-multiarch-print-prog-name=program-print-libgcc-file-nameThis is useful when you use -nostdlib or -nodefaultlibs but you do want to link with libgcc.a. You can do
gcc -nostdlib files... `gcc -print-libgcc-file-name`
-print-search-dirsThis is useful when gcc prints the error message
‘installation problem, cannot exec cpp0: No such file or directory’.
To resolve this you either need to put cpp0 and the other compiler
components where gcc expects to find them, or you can set the environment
variable GCC_EXEC_PREFIX to the directory where you installed them.
Don't forget the trailing ‘/’.
See Environment Variables.
-print-sysroot-print-sysroot-headers-suffix-dumpmachine-dumpversion-dumpspecs-feliminate-unused-debug-typesThese options control various sorts of optimizations.
Without any optimization option, the compiler's goal is to reduce the cost of compilation and to make debugging produce the expected results. Statements are independent: if you stop the program with a breakpoint between statements, you can then assign a new value to any variable or change the program counter to any other statement in the function and get exactly the results you would expect from the source code.
Turning on optimization flags makes the compiler attempt to improve the performance and/or code size at the expense of compilation time and possibly the ability to debug the program.
The compiler performs optimization based on the knowledge it has of the program. Compiling multiple files at once to a single output file mode allows the compiler to use information gained from all of the files when compiling each of them.
Not all optimizations are controlled directly by a flag. Only optimizations that have a flag are listed in this section.
Most optimizations are only enabled if an -O level is set on the command line. Otherwise they are disabled, even if individual optimization flags are specified.
Depending on the target and how GCC was configured, a slightly different set of optimizations may be enabled at each -O level than those listed here. You can invoke GCC with ‘-Q --help=optimizers’ to find out the exact set of optimizations that are enabled at each level. See Overall Options, for examples.
-O-O1With -O, the compiler tries to reduce code size and execution time, without performing any optimizations that take a great deal of compilation time.
-O turns on the following optimization flags:
-fauto-inc-dec
-fcompare-elim
-fcprop-registers
-fdce
-fdefer-pop
-fdelayed-branch
-fdse
-fguess-branch-probability
-fif-conversion2
-fif-conversion
-fipa-pure-const
-fipa-profile
-fipa-reference
-fmerge-constants
-fsplit-wide-types
-ftree-bit-ccp
-ftree-builtin-call-dce
-ftree-ccp
-ftree-ch
-ftree-copyrename
-ftree-dce
-ftree-dominator-opts
-ftree-dse
-ftree-forwprop
-ftree-fre
-ftree-phiprop
-ftree-sra
-ftree-pta
-ftree-ter
-funit-at-a-time
-O also turns on -fomit-frame-pointer on machines
where doing so does not interfere with debugging.
-O2-O2 turns on all optimization flags specified by -O. It also turns on the following optimization flags:
-fthread-jumps
-falign-functions -falign-jumps
-falign-loops -falign-labels
-fcaller-saves
-fcrossjumping
-fcse-follow-jumps -fcse-skip-blocks
-fdelete-null-pointer-checks
-fdevirtualize
-fexpensive-optimizations
-fgcse -fgcse-lm
-finline-small-functions
-findirect-inlining
-fipa-sra
-foptimize-sibling-calls
-fpartial-inlining
-fpeephole2
-fregmove
-freorder-blocks -freorder-functions
-frerun-cse-after-loop
-fsched-interblock -fsched-spec
-fschedule-insns -fschedule-insns2
-fstrict-aliasing -fstrict-overflow
-ftree-switch-conversion -ftree-tail-merge
-ftree-pre
-ftree-vrp
Please note the warning under -fgcse about
invoking -O2 on programs that use computed gotos.
-O3-O0-Os-Os disables the following optimization flags:
-falign-functions -falign-jumps -falign-loops
-falign-labels -freorder-blocks -freorder-blocks-and-partition
-fprefetch-loop-arrays -ftree-vect-loop-version
-OfastIf you use multiple -O options, with or without level numbers, the last such option is the one that is effective.
Options of the form -fflag specify machine-independent flags. Most flags have both positive and negative forms; the negative form of -ffoo would be -fno-foo. In the table below, only one of the forms is listed—the one you typically will use. You can figure out the other form by either removing ‘no-’ or adding it.
The following options control specific optimizations. They are either activated by -O options or are related to ones that are. You can use the following flags in the rare cases when “fine-tuning” of optimizations to be performed is desired.
-fno-default-inline-fno-defer-popDisabled at levels -O, -O2, -O3, -Os.
-fforward-propagateThis option is enabled by default at optimization levels -O,
-O2, -O3, -Os.
-ffp-contract=styleThe default is -ffp-contract=fast.
-fomit-frame-pointerOn some machines, such as the VAX, this flag has no effect, because
the standard calling sequence automatically handles the frame pointer
and nothing is saved by pretending it doesn't exist. The
machine-description macro FRAME_POINTER_REQUIRED controls
whether a target machine supports this flag. See Register Usage.
Starting with GCC version 4.6, the default setting (when not optimizing for size) for 32-bit Linux x86 and 32-bit Darwin x86 targets has been changed to -fomit-frame-pointer. The default can be reverted to -fno-omit-frame-pointer by configuring GCC with the --enable-frame-pointer configure option.
Enabled at levels -O, -O2, -O3, -Os.
-foptimize-sibling-callsEnabled at levels -O2, -O3, -Os.
-fno-inlinealways_inline attribute. This is the default when not
optimizing.
Single functions can be exempted from inlining by marking them
with the noinline attribute.
-finline-small-functionsEnabled at level -O2.
-findirect-inliningEnabled at level -O2.
-finline-functionsIf all calls to a given function are integrated, and the function is
declared static, then the function is normally not output as
assembler code in its own right.
Enabled at level -O3.
-finline-functions-called-oncestatic functions called once for inlining into their
caller even if they are not marked inline. If a call to a given
function is integrated, then the function is not output as assembler code
in its own right.
Enabled at levels -O1, -O2, -O3 and -Os.
-fearly-inliningalways_inline and functions whose body seems
smaller than the function call overhead early before doing
-fprofile-generate instrumentation and real inlining pass. Doing so
makes profiling significantly cheaper and usually inlining faster on programs
having large chains of nested wrapper functions.
Enabled by default.
-fipa-sraEnabled at levels -O2, -O3 and -Os.
-finline-limit=nInlining is actually controlled by a number of parameters, which may be specified individually by using --param name=value. The -finline-limit=n option sets some of these parameters as follows:
max-inline-insns-singlemax-inline-insns-autoSee below for a documentation of the individual parameters controlling inlining and for the defaults of these parameters.
Note: there may be no value to -finline-limit that results in default behavior.
Note: pseudo instruction represents, in this particular context, an
abstract measurement of function's size. In no way does it represent a count
of assembly instructions and as such its exact meaning might change from one
release to an another.
-fno-keep-inline-dllexportdllexport
attribute or declspec (See Declaring Attributes of Functions.)
-fkeep-inline-functionsstatic functions that are declared inline
into the object file, even if the function has been inlined into all
of its callers. This switch does not affect functions using the
extern inline extension in GNU C90. In C++, emit any and all
inline functions into the object file.
-fkeep-static-constsstatic const when optimization isn't turned
on, even if the variables aren't referenced.
GCC enables this option by default. If you want to force the compiler to
check if the variable was referenced, regardless of whether or not
optimization is turned on, use the -fno-keep-static-consts option.
-fmerge-constantsThis option is the default for optimized compilation if the assembler and linker support it. Use -fno-merge-constants to inhibit this behavior.
Enabled at levels -O, -O2, -O3, -Os.
-fmerge-all-constantsThis option implies -fmerge-constants. In addition to
-fmerge-constants this considers e.g. even constant initialized
arrays or initialized constant variables with integral or floating-point
types. Languages like C or C++ require each variable, including multiple
instances of the same variable in recursive calls, to have distinct locations,
so using this option will result in non-conforming
behavior.
-fmodulo-sched-fmodulo-sched-allow-regmoves-fno-branch-count-regThe default is -fbranch-count-reg.
-fno-function-cseThis option results in less efficient code, but some strange hacks that alter the assembler output may be confused by the optimizations performed when this option is not used.
The default is -ffunction-cse
-fno-zero-initialized-in-bssThis option turns off this behavior because some programs explicitly rely on variables going to the data section. E.g., so that the resulting executable can find the beginning of that section and/or make assumptions based on that.
The default is -fzero-initialized-in-bss.
-fmudflap -fmudflapth -fmudflapirenv MUDFLAP_OPTIONS=-help a.out
for its options.
Use -fmudflapth instead of -fmudflap to compile and to
link if your program is multi-threaded. Use -fmudflapir, in
addition to -fmudflap or -fmudflapth, if
instrumentation should ignore pointer reads. This produces less
instrumentation (and therefore faster execution) and still provides
some protection against outright memory corrupting writes, but allows
erroneously read data to propagate within a program.
-fthread-jumpsEnabled at levels -O2, -O3, -Os.
-fsplit-wide-typeslong
long on a 32-bit system, split the registers apart and allocate them
independently. This normally generates better code for those types,
but may make debugging more difficult.
Enabled at levels -O, -O2, -O3,
-Os.
-fcse-follow-jumpsif statement with an
else clause, CSE will follow the jump when the condition
tested is false.
Enabled at levels -O2, -O3, -Os.
-fcse-skip-blocksif statement with no else clause,
-fcse-skip-blocks causes CSE to follow the jump around the
body of the if.
Enabled at levels -O2, -O3, -Os.
-frerun-cse-after-loopEnabled at levels -O2, -O3, -Os.
-fgcseNote: When compiling a program using computed gotos, a GCC extension, you may get better run-time performance if you disable the global common subexpression elimination pass by adding -fno-gcse to the command line.
Enabled at levels -O2, -O3, -Os.
-fgcse-lmEnabled by default when gcse is enabled.
-fgcse-smNot enabled at any optimization level.
-fgcse-lasNot enabled at any optimization level.
-fgcse-after-reload-funsafe-loop-optimizations-fcrossjumpingEnabled at levels -O2, -O3, -Os.
-fauto-inc-dec-fdce-fdse-fif-conversionif-conversion2.
Enabled at levels -O, -O2, -O3, -Os.
-fif-conversion2Enabled at levels -O, -O2, -O3, -Os.
-fdelete-null-pointer-checksNote however that in some environments this assumption is not true. Use -fno-delete-null-pointer-checks to disable this optimization for programs that depend on that behavior.
Some targets, especially embedded ones, disable this option at all levels.
Otherwise it is enabled at all levels: -O0, -O1,
-O2, -O3, -Os. Passes that use the information
are enabled independently at different optimization levels.
-fdevirtualize-findirect-inlining) and interprocedural constant
propagation (-fipa-cp).
Enabled at levels -O2, -O3, -Os.
-fexpensive-optimizationsEnabled at levels -O2, -O3, -Os.
-freeEnabled for x86 at levels -O2, -O3.
-foptimize-register-move-fregmoveNote -fregmove and -foptimize-register-move are the same optimization.
Enabled at levels -O2, -O3, -Os.
-fira-algorithm=algorithm-fira-region=region-fira-loop-pressureThis option is enabled at level -O3 for some targets.
-fno-ira-share-save-slots-fno-ira-share-spill-slots-fira-verbose=n-fdelayed-branchEnabled at levels -O, -O2, -O3, -Os.
-fschedule-insnsEnabled at levels -O2, -O3.
-fschedule-insns2Enabled at levels -O2, -O3, -Os.
-fno-sched-interblock-fno-sched-spec-fsched-pressure-fsched-spec-load-fsched-spec-load-dangerous-fsched-stalled-insns-fsched-stalled-insns=n-fsched-stalled-insns-dep-fsched-stalled-insns-dep=n-fsched2-use-superblocksThis only makes sense when scheduling after register allocation, i.e. with
-fschedule-insns2 or at -O2 or higher.
-fsched-group-heuristic-fsched-critical-path-heuristic-fsched-spec-insn-heuristic-fsched-rank-heuristic-fsched-last-insn-heuristic-fsched-dep-count-heuristic-freschedule-modulo-scheduled-loops-fselective-scheduling-fselective-scheduling2-fsel-sched-pipelining-fsel-sched-pipelining-outer-loops-fshrink-wrap-fcaller-savesThis option is always enabled by default on certain machines, usually those which have no call-preserved registers to use instead.
Enabled at levels -O2, -O3, -Os.
-fcombine-stack-adjustmentsEnabled by default at -O1 and higher.
-fconserve-stack-ftree-reassoc-ftree-pre-ftree-forwprop-ftree-fre-ftree-phiprop-ftree-copy-prop-fipa-pure-const-fipa-reference-fipa-pta-fipa-profilecold, noreturn, static constructors or destructors) are identified. Cold
functions and loop less parts of functions executed once are then optimized for
size.
Enabled by default at -O and higher.
-fipa-cp-fipa-cp-clone-fipa-matrix-reorg-ftree-sink-ftree-bit-ccp-ftree-ccp-ftree-switch-conversion-ftree-tail-merge-ftree-dce-ftree-builtin-call-dceerrno but are otherwise side-effect free. This flag is
enabled by default at -O2 and higher if -Os is not also
specified.
-ftree-dominator-opts-ftree-dse-ftree-ch-ftree-loop-optimize-ftree-loop-linear-floop-interchange DO J = 1, M
DO I = 1, N
A(J, I) = A(J, I) * C
ENDDO
ENDDO
loop interchange will transform the loop as if the user had written:
DO I = 1, N
DO J = 1, M
A(J, I) = A(J, I) * C
ENDDO
ENDDO
which can be beneficial when N is larger than the caches,
because in Fortran, the elements of an array are stored in memory
contiguously by column, and the original loop iterates over rows,
potentially creating at each access a cache miss. This optimization
applies to all the languages supported by GCC and is not limited to
Fortran. To use this code transformation, GCC has to be configured
with --with-ppl and --with-cloog to enable the
Graphite loop transformation infrastructure.
-floop-strip-mine DO I = 1, N
A(I) = A(I) + C
ENDDO
loop strip mining will transform the loop as if the user had written:
DO II = 1, N, 51
DO I = II, min (II + 50, N)
A(I) = A(I) + C
ENDDO
ENDDO
This optimization applies to all the languages supported by GCC and is
not limited to Fortran. To use this code transformation, GCC has to
be configured with --with-ppl and --with-cloog to
enable the Graphite loop transformation infrastructure.
-floop-block DO I = 1, N
DO J = 1, M
A(J, I) = B(I) + C(J)
ENDDO
ENDDO
loop blocking will transform the loop as if the user had written:
DO II = 1, N, 51
DO JJ = 1, M, 51
DO I = II, min (II + 50, N)
DO J = JJ, min (JJ + 50, M)
A(J, I) = B(I) + C(J)
ENDDO
ENDDO
ENDDO
ENDDO
which can be beneficial when M is larger than the caches,
because the innermost loop will iterate over a smaller amount of data
which can be kept in the caches. This optimization applies to all the
languages supported by GCC and is not limited to Fortran. To use this
code transformation, GCC has to be configured with --with-ppl
and --with-cloog to enable the Graphite loop transformation
infrastructure.
-fgraphite-identity-floop-flatten-floop-parallelize-all-fcheck-data-deps-ftree-loop-if-convert-ftree-loop-if-convert-stores for (i = 0; i < N; i++)
if (cond)
A[i] = expr;
would be transformed to
for (i = 0; i < N; i++)
A[i] = cond ? expr : A[i];
potentially producing data races.
-ftree-loop-distribution DO I = 1, N
A(I) = B(I) + C
D(I) = E(I) * F
ENDDO
is transformed to
DO I = 1, N
A(I) = B(I) + C
ENDDO
DO I = 1, N
D(I) = E(I) * F
ENDDO
-ftree-loop-distribute-patternsThis pass distributes the initialization loops and generates a call to memset zero. For example, the loop
DO I = 1, N
A(I) = 0
B(I) = A(I) + I
ENDDO
is transformed to
DO I = 1, N
A(I) = 0
ENDDO
DO I = 1, N
B(I) = A(I) + I
ENDDO
and the initialization loop is transformed into a call to memset zero.
-ftree-loop-im-ftree-loop-ivcanon-fivopts-ftree-parallelize-loops=n-ftree-pta-ftree-sra-ftree-copyrename-ftree-ter-ftree-vectorize-ftree-slp-vectorize-ftree-vect-loop-version-fvect-cost-model-ftree-vrp-ftracer-funroll-loops-funroll-all-loops-fsplit-ivs-in-unrollerCombination of -fweb and CSE is often sufficient to obtain the same effect. However in cases the loop body is more complicated than a single basic block, this is not reliable. It also does not work at all on some of the architectures due to restrictions in the CSE pass.
This optimization is enabled by default.
-fvariable-expansion-in-unroller-fpartial-inliningEnabled at level -O2.
-fpredictive-commoningThis option is enabled at level -O3.
-fprefetch-loop-arraysThis option may generate better or worse code; results are highly dependent on the structure of loops within the source code.
Disabled at level -Os.
-fno-peephole-fno-peephole2-fpeephole is enabled by default.
-fpeephole2 enabled at levels -O2, -O3, -Os.
-fno-guess-branch-probabilityGCC will use heuristics to guess branch probabilities if they are not provided by profiling feedback (-fprofile-arcs). These heuristics are based on the control flow graph. If some branch probabilities are specified by ‘__builtin_expect’, then the heuristics will be used to guess branch probabilities for the rest of the control flow graph, taking the ‘__builtin_expect’ info into account. The interactions between the heuristics and ‘__builtin_expect’ can be complex, and in some cases, it may be useful to disable the heuristics so that the effects of ‘__builtin_expect’ are easier to understand.
The default is -fguess-branch-probability at levels
-O, -O2, -O3, -Os.
-freorder-blocksEnabled at levels -O2, -O3.
-freorder-blocks-and-partitionThis optimization is automatically turned off in the presence of
exception handling, for linkonce sections, for functions with a user-defined
section attribute and on any architecture that does not support named
sections.
-freorder-functions.text.hot for most frequently executed functions and
.text.unlikely for unlikely executed functions. Reordering is done by
the linker so object file format must support named sections and linker must
place them in a reasonable way.
Also profile feedback must be available in to make this option effective. See -fprofile-arcs for details.
Enabled at levels -O2, -O3, -Os.
-fstrict-aliasingunsigned int can alias an int, but not a
void* or a double. A character type may alias any other
type.
Pay special attention to code like this:
union a_union {
int i;
double d;
};
int f() {
union a_union t;
t.d = 3.0;
return t.i;
}
The practice of reading from a different union member than the one most recently written to (called “type-punning”) is common. Even with -fstrict-aliasing, type-punning is allowed, provided the memory is accessed through the union type. So, the code above will work as expected. See Structures unions enumerations and bit-fields implementation. However, this code might not:
int f() {
union a_union t;
int* ip;
t.d = 3.0;
ip = &t.i;
return *ip;
}
Similarly, access by taking the address, casting the resulting pointer and dereferencing the result has undefined behavior, even if the cast uses a union type, e.g.:
int f() {
double d = 3.0;
return ((union a_union *) &d)->i;
}
The -fstrict-aliasing option is enabled at levels
-O2, -O3, -Os.
-fstrict-overflowi + 10 > i will always be true for
signed i. This assumption is only valid if signed overflow is
undefined, as the expression is false if i + 10 overflows when
using twos complement arithmetic. When this option is in effect any
attempt to determine whether an operation on signed numbers will
overflow must be written carefully to not actually involve overflow.
This option also allows the compiler to assume strict pointer
semantics: given a pointer to an object, if adding an offset to that
pointer does not produce a pointer to the same object, the addition is
undefined. This permits the compiler to conclude that p + u >
p is always true for a pointer p and unsigned integer
u. This assumption is only valid because pointer wraparound is
undefined, as the expression is false if p + u overflows using
twos complement arithmetic.
See also the -fwrapv option. Using -fwrapv means that integer signed overflow is fully defined: it wraps. When -fwrapv is used, there is no difference between -fstrict-overflow and -fno-strict-overflow for integers. With -fwrapv certain types of overflow are permitted. For example, if the compiler gets an overflow when doing arithmetic on constants, the overflowed value can still be used with -fwrapv, but not otherwise.
The -fstrict-overflow option is enabled at levels
-O2, -O3, -Os.
-falign-functions-falign-functions=n-fno-align-functions and -falign-functions=1 are equivalent and mean that functions will not be aligned.
Some assemblers only support this flag when n is a power of two; in that case, it is rounded up.
If n is not specified or is zero, use a machine-dependent default.
Enabled at levels -O2, -O3.
-falign-labels-falign-labels=n-fno-align-labels and -falign-labels=1 are equivalent and mean that labels will not be aligned.
If -falign-loops or -falign-jumps are applicable and are greater than this value, then their values are used instead.
If n is not specified or is zero, use a machine-dependent default which is very likely to be ‘1’, meaning no alignment.
Enabled at levels -O2, -O3.
-falign-loops-falign-loops=n-fno-align-loops and -falign-loops=1 are equivalent and mean that loops will not be aligned.
If n is not specified or is zero, use a machine-dependent default.
Enabled at levels -O2, -O3.
-falign-jumps-falign-jumps=n-fno-align-jumps and -falign-jumps=1 are equivalent and mean that loops will not be aligned.
If n is not specified or is zero, use a machine-dependent default.
Enabled at levels -O2, -O3.
-funit-at-a-timeEnabled by default.
-fno-toplevel-reorderasm
statements. Output them in the same order that they appear in the
input file. When this option is used, unreferenced static variables
will not be removed. This option is intended to support existing code
that relies on a particular ordering. For new code, it is better to
use attributes.
Enabled at level -O0. When disabled explicitly, it also implies
-fno-section-anchors, which is otherwise enabled at -O0 on some
targets.
-fwebEnabled by default with -funroll-loops.
-fwhole-programmain
and those merged by attribute externally_visible become static functions
and in effect are optimized more aggressively by interprocedural optimizers. If gold is used as the linker plugin, externally_visible attributes are automatically added to functions (not variable yet due to a current gold issue) that are accessed outside of LTO objects according to resolution file produced by gold. For other linkers that cannot generate resolution file, explicit externally_visible attributes are still necessary.
While this option is equivalent to proper use of the static keyword for
programs consisting of a single file, in combination with option
-flto this flag can be used to
compile many smaller scale programs since the functions and variables become
local for the whole combined compilation unit, not for the single source file
itself.
This option implies -fwhole-file for Fortran programs.
-flto[=n]To use the link-time optimizer, -flto needs to be specified at compile time and during the final link. For example:
gcc -c -O2 -flto foo.c
gcc -c -O2 -flto bar.c
gcc -o myprog -flto -O2 foo.o bar.o
The first two invocations to GCC save a bytecode representation of GIMPLE into special ELF sections inside foo.o and bar.o. The final invocation reads the GIMPLE bytecode from foo.o and bar.o, merges the two files into a single internal image, and compiles the result as usual. Since both foo.o and bar.o are merged into a single image, this causes all the interprocedural analyses and optimizations in GCC to work across the two files as if they were a single one. This means, for example, that the inliner is able to inline functions in bar.o into functions in foo.o and vice-versa.
Another (simpler) way to enable link-time optimization is:
gcc -o myprog -flto -O2 foo.c bar.c
The above generates bytecode for foo.c and bar.c, merges them together into a single GIMPLE representation and optimizes them as usual to produce myprog.
The only important thing to keep in mind is that to enable link-time optimizations the -flto flag needs to be passed to both the compile and the link commands.
To make whole program optimization effective, it is necessary to make certain whole program assumptions. The compiler needs to know what functions and variables can be accessed by libraries and runtime outside of the link-time optimized unit. When supported by the linker, the linker plugin (see -fuse-linker-plugin) passes information to the compiler about used and externally visible symbols. When the linker plugin is not available, -fwhole-program should be used to allow the compiler to make these assumptions, which leads to more aggressive optimization decisions.
Note that when a file is compiled with -flto, the generated object file is larger than a regular object file because it contains GIMPLE bytecodes and the usual final code. This means that object files with LTO information can be linked as normal object files; if -flto is not passed to the linker, no interprocedural optimizations are applied.
Additionally, the optimization flags used to compile individual files are not necessarily related to those used at link time. For instance,
gcc -c -O0 -flto foo.c
gcc -c -O0 -flto bar.c
gcc -o myprog -flto -O3 foo.o bar.o
This produces individual object files with unoptimized assembler code, but the resulting binary myprog is optimized at -O3. If, instead, the final binary is generated without -flto, then myprog is not optimized.
When producing the final binary with -flto, GCC only applies link-time optimizations to those files that contain bytecode. Therefore, you can mix and match object files and libraries with GIMPLE bytecodes and final object code. GCC automatically selects which files to optimize in LTO mode and which files to link without further processing.
There are some code generation flags preserved by GCC when generating bytecodes, as they need to be used during the final link stage. Currently, the following options are saved into the GIMPLE bytecode files: -fPIC, -fcommon and all the -m target flags.
At link time, these options are read in and reapplied. Note that the current implementation makes no attempt to recognize conflicting values for these options. If different files have conflicting option values (e.g., one file is compiled with -fPIC and another isn't), the compiler simply uses the last value read from the bytecode files. It is recommended, then, that you compile all the files participating in the same link with the same options.
If LTO encounters objects with C linkage declared with incompatible types in separate translation units to be linked together (undefined behavior according to ISO C99 6.2.7), a non-fatal diagnostic may be issued. The behavior is still undefined at run time.
Another feature of LTO is that it is possible to apply interprocedural optimizations on files written in different languages. This requires support in the language front end. Currently, the C, C++ and Fortran front ends are capable of emitting GIMPLE bytecodes, so something like this should work:
gcc -c -flto foo.c
g++ -c -flto bar.cc
gfortran -c -flto baz.f90
g++ -o myprog -flto -O3 foo.o bar.o baz.o -lgfortran
Notice that the final link is done with g++ to get the C++ runtime libraries and -lgfortran is added to get the Fortran runtime libraries. In general, when mixing languages in LTO mode, you should use the same link command options as when mixing languages in a regular (non-LTO) compilation; all you need to add is -flto to all the compile and link commands.
If object files containing GIMPLE bytecode are stored in a library archive, say libfoo.a, it is possible to extract and use them in an LTO link if you are using a linker with plugin support. To enable this feature, use the flag -fuse-linker-plugin at link time:
gcc -o myprog -O2 -flto -fuse-linker-plugin a.o b.o -lfoo
With the linker plugin enabled, the linker extracts the needed GIMPLE files from libfoo.a and passes them on to the running GCC to make them part of the aggregated GIMPLE image to be optimized.
If you are not using a linker with plugin support and/or do not enable the linker plugin, then the objects inside libfoo.a are extracted and linked as usual, but they do not participate in the LTO optimization process.
Link-time optimizations do not require the presence of the whole program to operate. If the program does not require any symbols to be exported, it is possible to combine -flto and -fwhole-program to allow the interprocedural optimizers to use more aggressive assumptions which may lead to improved optimization opportunities. Use of -fwhole-program is not needed when linker plugin is active (see -fuse-linker-plugin).
The current implementation of LTO makes no attempt to generate bytecode that is portable between different types of hosts. The bytecode files are versioned and there is a strict version check, so bytecode files generated in one version of GCC will not work with an older/newer version of GCC.
Link-time optimization does not work well with generation of debugging information. Combining -flto with -g is currently experimental and expected to produce wrong results.
If you specify the optional n, the optimization and code generation done at link time is executed in parallel using n parallel jobs by utilizing an installed make program. The environment variable MAKE may be used to override the program used. The default value for n is 1.
You can also specify -flto=jobserver to use GNU make's job server mode to determine the number of parallel jobs. This is useful when the Makefile calling GCC is already executing in parallel. You must prepend a ‘+’ to the command recipe in the parent Makefile for this to work. This option likely only works if MAKE is GNU make.
This option is disabled by default
-flto-partition=alg1to1 to specify a partitioning mirroring
the original source files or balanced to specify partitioning
into equally sized chunks (whenever possible). Specifying none
as an algorithm disables partitioning and streaming completely. The
default value is balanced.
-flto-compression-level=n-flto-reportDisabled by default.
-fuse-linker-pluginThis option enables the extraction of object files with GIMPLE bytecode out
of library archives. This improves the quality of optimization by exposing
more code to the link-time optimizer. This information specifies what
symbols can be accessed externally (by non-LTO object or during dynamic
linking). Resulting code quality improvements on binaries (and shared
libraries that use hidden visibility) are similar to -fwhole-program.
See -flto for a description of the effect of this flag and how to
use it.
This option is enabled by default when LTO support in GCC is enabled
and GCC was configured for use with
a linker supporting plugins (GNU ld 2.21 or newer or gold).
-ffat-lto-objects-fno-fat-lto-objects improves compilation time over plain LTO, but requires the complete toolchain to be aware of LTO. It requires a linker with linker plugin support for basic functionality. Additionally, nm, ar and ranlib need to support linker plugins to allow a full-featured build environment (capable of building static libraries etc).
The default is -ffat-lto-objects but this default is intended to
change in future releases when linker plugin enabled environments become more
common.
-fcompare-elimThis pass only applies to certain targets that cannot explicitly represent the comparison operation before register allocation is complete.
Enabled at levels -O, -O2, -O3, -Os.
-fcprop-registersEnabled at levels -O, -O2, -O3, -Os.
-fprofile-correction-fprofile-dir=path-fprofile-generate-fprofile-generate=pathThe following options are enabled: -fprofile-arcs, -fprofile-values, -fvpt.
If path is specified, GCC will look at the path to find
the profile feedback data files. See -fprofile-dir.
-fprofile-use-fprofile-use=pathThe following options are enabled: -fbranch-probabilities, -fvpt,
-funroll-loops, -fpeel-loops, -ftracer
By default, GCC emits an error message if the feedback profiles do not match the source code. This error can be turned into a warning by using -Wcoverage-mismatch. Note this may result in poorly optimized code.
If path is specified, GCC will look at the path to find the profile feedback data files. See -fprofile-dir.
The following options control compiler behavior regarding floating-point arithmetic. These options trade off between speed and correctness. All must be specifically enabled.
-ffloat-storeThis option prevents undesirable excess precision on machines such as
the 68000 where the floating registers (of the 68881) keep more
precision than a double is supposed to have. Similarly for the
x86 architecture. For most programs, the excess precision does only
good, but a few programs rely on the precise definition of IEEE floating
point. Use -ffloat-store for such programs, after modifying
them to store all pertinent intermediate computations into variables.
-fexcess-precision=stylefloat and double types and the processor does not
support operations rounding to those types. By default,
-fexcess-precision=fast is in effect; this means that
operations are carried out in the precision of the registers and that
it is unpredictable when rounding to the types specified in the source
code takes place. When compiling C, if
-fexcess-precision=standard is specified then excess
precision will follow the rules specified in ISO C99; in particular,
both casts and assignments cause values to be rounded to their
semantic types (whereas -ffloat-store only affects
assignments). This option is enabled by default for C if a strict
conformance option such as -std=c99 is used.
-fexcess-precision=standard is not implemented for languages
other than C, and has no effect if
-funsafe-math-optimizations or -ffast-math is
specified. On the x86, it also has no effect if -mfpmath=sse
or -mfpmath=sse+387 is specified; in the former case, IEEE
semantics apply without excess precision, and in the latter, rounding
is unpredictable.
-ffast-mathThis option causes the preprocessor macro __FAST_MATH__ to be defined.
This option is not turned on by any -O option besides
-Ofast since it can result in incorrect output for programs
that depend on an exact implementation of IEEE or ISO rules/specifications
for math functions. It may, however, yield faster code for programs
that do not require the guarantees of these specifications.
-fno-math-errnoThis option is not turned on by any -O option since it can result in incorrect output for programs that depend on an exact implementation of IEEE or ISO rules/specifications for math functions. It may, however, yield faster code for programs that do not require the guarantees of these specifications.
The default is -fmath-errno.
On Darwin systems, the math library never sets errno. There is
therefore no reason for the compiler to consider the possibility that
it might, and -fno-math-errno is the default.
-funsafe-math-optimizationsThis option is not turned on by any -O option since it can result in incorrect output for programs that depend on an exact implementation of IEEE or ISO rules/specifications for math functions. It may, however, yield faster code for programs that do not require the guarantees of these specifications. Enables -fno-signed-zeros, -fno-trapping-math, -fassociative-math and -freciprocal-math.
The default is -fno-unsafe-math-optimizations.
-fassociative-math(x + 2**52) - 2**52. May also reorder floating-point comparisons
and thus may not be used when ordered comparisons are required.
This option requires that both -fno-signed-zeros and
-fno-trapping-math be in effect. Moreover, it doesn't make
much sense with -frounding-math. For Fortran the option
is automatically enabled when both -fno-signed-zeros and
-fno-trapping-math are in effect.
The default is -fno-associative-math.
-freciprocal-mathx / y
can be replaced with x * (1/y), which is useful if (1/y)
is subject to common subexpression elimination. Note that this loses
precision and increases the number of flops operating on the value.
The default is -fno-reciprocal-math.
-ffinite-math-onlyThis option is not turned on by any -O option since it can result in incorrect output for programs that depend on an exact implementation of IEEE or ISO rules/specifications for math functions. It may, however, yield faster code for programs that do not require the guarantees of these specifications.
The default is -fno-finite-math-only.
-fno-signed-zerosThe default is -fsigned-zeros.
-fno-trapping-mathThis option should never be turned on by any -O option since it can result in incorrect output for programs that depend on an exact implementation of IEEE or ISO rules/specifications for math functions.
The default is -ftrapping-math.
-frounding-mathThe default is -fno-rounding-math.
This option is experimental and does not currently guarantee to
disable all GCC optimizations that are affected by rounding mode.
Future versions of GCC may provide finer control of this setting
using C99's FENV_ACCESS pragma. This command-line option
will be used to specify the default state for FENV_ACCESS.
-fsignaling-nansThis option causes the preprocessor macro __SUPPORT_SNAN__ to
be defined.
The default is -fno-signaling-nans.
This option is experimental and does not currently guarantee to
disable all GCC optimizations that affect signaling NaN behavior.
-fsingle-precision-constant-fcx-limited-rangeNaN
+ I*NaN, with an attempt to rescue the situation in that case. The
default is -fno-cx-limited-range, but is enabled by
-ffast-math.
This option controls the default setting of the ISO C99
CX_LIMITED_RANGE pragma. Nevertheless, the option applies to
all languages.
-fcx-fortran-rulesNaN
+ I*NaN, with an attempt to rescue the situation in that case.
The default is -fno-cx-fortran-rules.
The following options control optimizations that may improve performance, but are not enabled by any -O options. This section includes experimental options that may produce broken code.
-fbranch-probabilitiesWith -fbranch-probabilities, GCC puts a
‘REG_BR_PROB’ note on each ‘JUMP_INSN’ and ‘CALL_INSN’.
These can be used to improve optimization. Currently, they are only
used in one place: in reorg.c, instead of guessing which path a
branch is most likely to take, the ‘REG_BR_PROB’ values are used to
exactly determine which path is taken more often.
-fprofile-valuesWith -fbranch-probabilities, it reads back the data gathered from profiling values of expressions for usage in optimizations.
Enabled with -fprofile-generate and -fprofile-use.
-fvptWith -fbranch-probabilities, it reads back the data gathered
and actually performs the optimizations based on them.
Currently the optimizations include specialization of division operation
using the knowledge about the value of the denominator.
-frename-registersEnabled by default with -funroll-loops and -fpeel-loops.
-ftracerEnabled with -fprofile-use.
-funroll-loopsEnabled with -fprofile-use.
-funroll-all-loops-fpeel-loopsEnabled with -fprofile-use.
-fmove-loop-invariants-funswitch-loops-ffunction-sections-fdata-sectionsUse these options on systems where the linker can perform optimizations to improve locality of reference in the instruction space. Most systems using the ELF object format and SPARC processors running Solaris 2 have linkers with such optimizations. AIX may have these optimizations in the future.
Only use these options when there are significant benefits from doing
so. When you specify these options, the assembler and linker will
create larger object and executable files and will also be slower.
You will not be able to use gprof on all systems if you
specify this option and you may have problems with debugging if
you specify both this option and -g.
-fbranch-target-load-optimize-fbranch-target-load-optimize2-fbtr-bb-exclusive-fstack-protector-fstack-protector-all-fsection-anchorsFor example, the implementation of the following function foo:
static int a, b, c;
int foo (void) { return a + b + c; }
would usually calculate the addresses of all three variables, but if you compile it with -fsection-anchors, it will access the variables from a common anchor point instead. The effect is similar to the following pseudocode (which isn't valid C):
int foo (void)
{
register int *xr = &x;
return xr[&a - &x] + xr[&b - &x] + xr[&c - &x];
}
Not all targets support this option.
--param name=valueThe names of specific parameters, and the meaning of the values, are tied to the internals of the compiler, and are subject to change without notice in future releases.
In each case, the value is an integer. The allowable choices for name are given in the following table:
predictable-branch-outcomemax-crossjump-edgesmin-crossjump-insnsmax-grow-copy-bb-insnsmax-goto-duplication-insnsmax-delay-slot-insn-searchmax-delay-slot-live-searchmax-gcse-memorymax-gcse-insertion-ratiomax-pending-list-lengthmax-modulo-backtrack-attemptsmax-inline-insns-singlemax-inline-insns-autolarge-function-insnslarge-function-growthlarge-unit-insnsinline-unit-growthipcp-unit-growthlarge-stack-framelarge-stack-frame-growthmax-inline-insns-recursivemax-inline-insns-recursive-autoFor functions declared inline --param max-inline-insns-recursive is
taken into account. For function not declared inline, recursive inlining
happens only when -finline-functions (included in -O3) is
enabled and --param max-inline-insns-recursive-auto is used. The
default value is 450.
max-inline-recursive-depthmax-inline-recursive-depth-autoFor functions declared inline --param max-inline-recursive-depth is
taken into account. For function not declared inline, recursive inlining
happens only when -finline-functions (included in -O3) is
enabled and --param max-inline-recursive-depth-auto is used. The
default value is 8.
min-inline-recursive-probabilityWhen profile feedback is available (see -fprofile-generate) the actual
recursion depth can be guessed from probability that function will recurse via
given call expression. This parameter limits inlining only to call expression
whose probability exceeds given threshold (in percents). The default value is
10.
early-inlining-insnsmax-early-inliner-iterationsmax-early-inliner-iterationscomdat-sharing-probabilitycomdat-sharing-probabilitymin-vect-loop-boundgcse-cost-distance-ratiogcse-unrestricted-costmax-hoist-depthmax-tail-merge-comparisonsmax-tail-merge-iterationsmax-unrolled-insnsmax-average-unrolled-insnsmax-unroll-timesmax-peeled-insnsmax-peel-timesmax-completely-peeled-insnsmax-completely-peel-timesmax-completely-peel-loop-nest-depthmax-unswitch-insnsmax-unswitch-levellim-expensiveiv-consider-all-candidates-boundiv-max-considered-usesiv-always-prune-cand-set-boundscev-max-expr-sizescev-max-expr-complexityomega-max-varsomega-max-geqsomega-max-eqsomega-max-wild-cardsomega-hash-table-sizeomega-max-keysomega-eliminate-redundant-constraintsvect-max-version-for-alignment-checksvect-max-version-for-alias-checksmax-iterations-to-trackhot-bb-count-fractionhot-bb-frequency-fractionmax-predicted-iterationsalign-thresholdalign-loop-iterationstracer-dynamic-coveragetracer-dynamic-coverage-feedbackThe tracer-dynamic-coverage-feedback is used only when profile
feedback is available. The real profiles (as opposed to statically estimated
ones) are much less balanced allowing the threshold to be larger value.
tracer-max-code-growthtracer-min-branch-ratiotracer-min-branch-ratiotracer-min-branch-ratio-feedbackSimilarly to tracer-dynamic-coverage two values are present, one for
compilation for profile feedback and one for compilation without. The value
for compilation with profile feedback needs to be more conservative (higher) in
order to make tracer effective.
max-cse-path-lengthmax-cse-insnsggc-min-expandThe default is 30% + 70% * (RAM/1GB) with an upper bound of 100% when
RAM >= 1GB. If getrlimit is available, the notion of "RAM" is
the smallest of actual RAM and RLIMIT_DATA or RLIMIT_AS. If
GCC is not able to calculate RAM on a particular platform, the lower
bound of 30% is used. Setting this parameter and
ggc-min-heapsize to zero causes a full collection to occur at
every opportunity. This is extremely slow, but can be useful for
debugging.
ggc-min-heapsizeThe default is the smaller of RAM/8, RLIMIT_RSS, or a limit that
tries to ensure that RLIMIT_DATA or RLIMIT_AS are not exceeded, but
with a lower bound of 4096 (four megabytes) and an upper bound of
131072 (128 megabytes). If GCC is not able to calculate RAM on a
particular platform, the lower bound is used. Setting this parameter
very large effectively disables garbage collection. Setting this
parameter and ggc-min-expand to zero causes a full collection
to occur at every opportunity.
max-reload-search-insnsmax-cselib-memory-locationsreorder-blocks-duplicatereorder-blocks-duplicate-feedbackThe reorder-block-duplicate-feedback is used only when profile
feedback is available and may be set to higher values than
reorder-block-duplicate since information about the hot spots is more
accurate.
max-sched-ready-insnsmax-sched-region-blocksmax-pipeline-region-blocksmax-sched-region-insnsmax-pipeline-region-insnsmin-spec-probmax-sched-extend-regions-itersmax-sched-insn-conflict-delaysched-spec-prob-cutoffsched-mem-true-dep-costselsched-max-lookaheadselsched-max-sched-timesselsched-max-insns-to-renamesms-min-scmax-last-value-rtlinteger-share-limitmin-virtual-mappingsvirtual-mappings-ratiossp-buffer-sizemax-jump-thread-duplication-stmtsmax-fields-for-field-sensitiveprefetch-latencysimultaneous-prefetchesl1-cache-line-sizel1-cache-sizel2-cache-sizemin-insn-to-prefetch-ratioprefetch-min-insn-to-mem-ratiouse-canonical-typesswitch-conversion-max-branch-ratiomax-partial-antic-lengthsccvn-max-scc-sizeira-max-loops-numira-max-conflict-table-sizeira-loop-reserved-regsloop-invariant-max-bbs-in-looploop-max-datarefs-for-datadepsmax-vartrack-sizemax-vartrack-expr-depthmin-nondebug-insn-uidipa-sra-ptr-growth-factortm-max-aggregate-sizegraphite-max-nb-scop-paramsgraphite-max-bbs-per-functionloop-block-tile-sizeipa-cp-value-list-sizelto-partitionslto-minpartitioncxx-max-namespaces-for-diagnostic-helpsink-frequency-thresholdmax-stores-to-sinkallow-load-data-racesallow-store-data-racesallow-packed-load-data-racesallow-packed-store-data-racescase-values-thresholdtree-reassoc-widthThese options control the C preprocessor, which is run on each C source file before actual compilation.
If you use the -E option, nothing is done except preprocessing. Some of these options make sense only together with -E because they cause the preprocessor output to be unsuitable for actual compilation.
-Wp,option-Xpreprocessor optionIf you want to pass an option that takes an argument, you must use -Xpreprocessor twice, once for the option and once for the argument.
-D name1.
-D name=definitionIf you are invoking the preprocessor from a shell or shell-like program you may need to use the shell's quoting syntax to protect characters such as spaces that have a meaning in the shell syntax.
If you wish to define a function-like macro on the command line, write its argument list with surrounding parentheses before the equals sign (if any). Parentheses are meaningful to most shells, so you will need to quote the option. With sh and csh, -D'name(args...)=definition' works.
-D and -U options are processed in the order they
are given on the command line. All -imacros file and
-include file options are processed after all
-D and -U options.
-U name-undef-I dir=, then the = will be replaced
by the sysroot prefix; see --sysroot and -isysroot.
-o file-Wall#if expressions. Note that many of the
preprocessor's warnings are on by default and have no options to
control them.
-Wcomment-Wcomments-WtrigraphsThis option is implied by -Wall. If -Wall is not
given, this option is still enabled unless trigraphs are enabled. To
get trigraph conversion without warnings, but get the other
-Wall warnings, use ‘-trigraphs -Wall -Wno-trigraphs’.
-Wtraditional-Wundef-Wunused-macrosBuilt-in macros, macros defined on the command line, and macros defined in include files are not warned about.
Note: If a macro is actually used, but only used in skipped conditional blocks, then CPP will report it as unused. To avoid the warning in such a case, you might improve the scope of the macro's definition by, for example, moving it into the first skipped block. Alternatively, you could provide a dummy use with something like:
#if defined the_macro_causing_the_warning
#endif
-Wendif-labels #if FOO
...
#else FOO
...
#endif FOO
The second and third FOO should be in comments, but often are not
in older programs. This warning is on by default.
-Werror-Wsystem-headers-w-pedantic-pedantic-errors-MUnless specified explicitly (with -MT or -MQ), the object file name consists of the name of the source file with any suffix replaced with object file suffix and with any leading directory parts removed. If there are many included files then the rule is split into several lines using ‘\’-newline. The rule has no commands.
This option does not suppress the preprocessor's debug output, such as -dM. To avoid mixing such debug output with the dependency rules you should explicitly specify the dependency output file with -MF, or use an environment variable like DEPENDENCIES_OUTPUT (see Environment Variables). Debug output will still be sent to the regular output stream as normal.
Passing -M to the driver implies -E, and suppresses
warnings with an implicit -w.
-MMThis implies that the choice of angle brackets or double quotes in an ‘#include’ directive does not in itself determine whether that header will appear in -MM dependency output. This is a slight change in semantics from GCC versions 3.0 and earlier.
-MF fileWhen used with the driver options -MD or -MMD,
-MF overrides the default dependency output file.
-MG#include directive without prepending any path. -MG
also suppresses preprocessed output, as a missing header file renders
this useless.
This feature is used in automatic updating of makefiles.
-MPThis is typical output:
test.o: test.c test.h
test.h:
-MT targetAn -MT option will set the target to be exactly the string you specify. If you want multiple targets, you can specify them as a single argument to -MT, or use multiple -MT options.
For example, -MT '$(objpfx)foo.o' might give
$(objpfx)foo.o: foo.c
-MQ target$$(objpfx)foo.o: foo.c
The default target is automatically quoted, as if it were given with
-MQ.
-MDIf -MD is used in conjunction with -E, any -o switch is understood to specify the dependency output file (see -MF), but if used without -E, each -o is understood to specify a target object file.
Since -E is not implied, -MD can be used to generate
a dependency output file as a side-effect of the compilation process.
-MMD-fpch-deps-fpch-preprocess#pragma,
#pragma GCC pch_preprocess "filename" in the output to mark
the place where the precompiled header was found, and its filename.
When -fpreprocessed is in use, GCC recognizes this #pragma
and loads the PCH.
This option is off by default, because the resulting preprocessed output is only really suitable as input to GCC. It is switched on by -save-temps.
You should not write this #pragma in your own code, but it is
safe to edit the filename if the PCH file is available in a different
location. The filename may be absolute or it may be relative to GCC's
current directory.
-x c-x c++-x objective-c-x assembler-with-cppNote: Previous versions of cpp accepted a -lang option
which selected both the language and the standards conformance level.
This option has been removed, because it conflicts with the -l
option.
-std=standard-ansistandard may be one of:
c90c89iso9899:1990The -ansi option is equivalent to -std=c90.
iso9899:199409iso9899:1999c99iso9899:199xc9xiso9899:2011c11c1xgnu90gnu89gnu99gnu9xgnu11gnu1xc++98gnu++98-I-#include "file"; they are not searched for
#include <file>. If additional directories are
specified with -I options after the -I-, those
directories are searched for all ‘#include’ directives.
In addition, -I- inhibits the use of the directory of the current
file directory as the first search directory for #include "file".
This option has been deprecated.
-nostdinc-nostdinc++-include file#include "file" appeared as the first
line of the primary source file. However, the first directory searched
for file is the preprocessor's working directory instead of
the directory containing the main source file. If not found there, it
is searched for in the remainder of the #include "..." search
chain as normal.
If multiple -include options are given, the files are included
in the order they appear on the command line.
-imacros fileAll files specified by -imacros are processed before all files
specified by -include.
-idirafter dir=, then the = will be replaced
by the sysroot prefix; see --sysroot and -isysroot.
-iprefix prefix-iwithprefix dir-iwithprefixbefore dir-isysroot dir-imultilib dir-isystem dir=, then the = will be replaced
by the sysroot prefix; see --sysroot and -isysroot.
-iquote dir#include "file"; they are not searched for
#include <file>, before all directories specified by
-I and before the standard system directories.
If dir begins with =, then the = will be replaced
by the sysroot prefix; see --sysroot and -isysroot.
-fdirectives-onlyThe option's behavior depends on the -E and -fpreprocessed options.
With -E, preprocessing is limited to the handling of directives
such as #define, #ifdef, and #error. Other
preprocessor operations, such as macro expansion and trigraph
conversion are not performed. In addition, the -dD option is
implicitly enabled.
With -fpreprocessed, predefinition of command line and most
builtin macros is disabled. Macros such as __LINE__, which are
contextually dependent, are handled normally. This enables compilation of
files previously preprocessed with -E -fdirectives-only.
With both -E and -fpreprocessed, the rules for
-fpreprocessed take precedence. This enables full preprocessing of
files previously preprocessed with -E -fdirectives-only.
-fdollars-in-identifiers-fextended-identifiers-fpreprocessed-fpreprocessed is implicit if the input file has one of the
extensions ‘.i’, ‘.ii’ or ‘.mi’. These are the
extensions that GCC uses for preprocessed files created by
-save-temps.
-ftabstop=width-fdebug-cpp {‘P’:/file/path;‘F’:/includer/path;‘L’:line_num;‘C’:col_num;‘S’:system_header_p;‘M’:map_address;‘E’:macro_expansion_p,‘loc’:location}
When used without -E, this option has no effect.
-ftrack-macro-expansion[=level]-fexec-charset=charseticonv library routine.
-fwide-exec-charset=charsetwchar_t. As with
-fexec-charset, charset can be any encoding supported
by the system's iconv library routine; however, you will have
problems with encodings that do not fit exactly in wchar_t.
-finput-charset=charseticonv library routine.
-fworking-directory#line directives are emitted whatsoever.
-fno-show-column-A predicate=answer-A -predicate=answer-dCHARStouch foo.h; cpp -dM foo.h
will show all the predefined macros.
If you use -dM without the -E option, -dM is
interpreted as a synonym for -fdump-rtl-mach.
See Debugging Options.
-P-CYou should be prepared for side effects when using -C; it
causes the preprocessor to treat comments as tokens in their own right.
For example, comments appearing at the start of what would be a
directive line have the effect of turning that line into an ordinary
source line, since the first token on the line is no longer a ‘#’.
-CCIn addition to the side-effects of the -C option, the -CC option causes all C++-style comments inside a macro to be converted to C-style comments. This is to prevent later use of that macro from inadvertently commenting out the remainder of the source line.
The -CC option is generally used to support lint comments.
-traditional-cpp-trigraphsThe nine trigraphs and their replacements are
Trigraph: ??( ??) ??< ??> ??= ??/ ??' ??! ??-
Replacement: [ ] { } # \ ^ | ~
-remap--help--target-help-v-H-version--versionYou can pass options to the assembler.
-Wa,option-Xassembler optionIf you want to pass an option that takes an argument, you must use -Xassembler twice, once for the option and once for the argument.
These options come into play when the compiler links object files into an executable output file. They are meaningless if the compiler is not doing a link step.
-c-S-E-llibrary-l libraryIt makes a difference where in the command you write this option; the linker searches and processes libraries and object files in the order they are specified. Thus, ‘foo.o -lz bar.o’ searches library ‘z’ after file foo.o but before bar.o. If bar.o refers to functions in ‘z’, those functions may not be loaded.
The linker searches a standard list of directories for the library, which is actually a file named liblibrary.a. The linker then uses this file as if it had been specified precisely by name.
The directories searched include several standard system directories plus any that you specify with -L.
Normally the files found this way are library files—archive files
whose members are object files. The linker handles an archive file by
scanning through it for members which define symbols that have so far
been referenced but not defined. But if the file that is found is an
ordinary object file, it is linked in the usual fashion. The only
difference between using an -l option and specifying a file name
is that -l surrounds library with ‘lib’ and ‘.a’
and searches several directories.
-lobjc-nostartfiles-nodefaultlibs-static-libgcc
or -shared-libgcc, will be ignored.
The standard startup files are used normally, unless -nostartfiles
is used. The compiler may generate calls to memcmp,
memset, memcpy and memmove.
These entries are usually resolved by entries in
libc. These entry points should be supplied through some other
mechanism when this option is specified.
-nostdlib-static-libgcc or -shared-libgcc, will be ignored.
The compiler may generate calls to memcmp, memset,
memcpy and memmove.
These entries are usually resolved by entries in
libc. These entry points should be supplied through some other
mechanism when this option is specified.
One of the standard libraries bypassed by -nostdlib and
-nodefaultlibs is libgcc.a, a library of internal subroutines
which GCC uses to overcome shortcomings of particular machines, or special
needs for some languages.
(See Interfacing to GCC Output,
for more discussion of libgcc.a.)
In most cases, you need libgcc.a even when you want to avoid
other standard libraries. In other words, when you specify -nostdlib
or -nodefaultlibs you should usually specify -lgcc as well.
This ensures that you have no unresolved references to internal GCC
library subroutines. (For example, ‘__main’, used to ensure C++
constructors will be called; see collect2.)
-pie-rdynamicdlopen or to allow obtaining backtraces
from within a program.
-s-static-shared-shared-libgcc-static-libgccThere are several situations in which an application should use the shared libgcc instead of the static version. The most common of these is when the application wishes to throw and catch exceptions across different shared libraries. In that case, each of the libraries as well as the application itself should use the shared libgcc.
Therefore, the G++ and GCJ drivers automatically add -shared-libgcc whenever you build a shared library or a main executable, because C++ and Java programs typically use exceptions, so this is the right thing to do.
If, instead, you use the GCC driver to create shared libraries, you may find that they will not always be linked with the shared libgcc. If GCC finds, at its configuration time, that you have a non-GNU linker or a GNU linker that does not support option --eh-frame-hdr, it will link the shared version of libgcc into shared libraries by default. Otherwise, it will take advantage of the linker and optimize away the linking with the shared version of libgcc, linking with the static version of libgcc by default. This allows exceptions to propagate through such shared libraries, without incurring relocation costs at library load time.
However, if a library or main executable is supposed to throw or catch
exceptions, you must link it using the G++ or GCJ driver, as appropriate
for the languages used in the program, or using the option
-shared-libgcc, such that it is linked with the shared
libgcc.
-static-libstdc++-symbolic-T script-Xlinker optionIf you want to pass an option that takes a separate argument, you must use -Xlinker twice, once for the option and once for the argument. For example, to pass -assert definitions, you must write ‘-Xlinker -assert -Xlinker definitions’. It does not work to write -Xlinker "-assert definitions", because this passes the entire string as a single argument, which is not what the linker expects.
When using the GNU linker, it is usually more convenient to pass
arguments to linker options using the option=value
syntax than as separate arguments. For example, you can specify
‘-Xlinker -Map=output.map’ rather than
‘-Xlinker -Map -Xlinker output.map’. Other linkers may not support
this syntax for command-line options.
-Wl,option-u symbolThese options specify directories to search for header files, for libraries and for parts of the compiler:
-IdirIf a standard system include directory, or a directory specified with
-isystem, is also specified with -I, the -I
option will be ignored. The directory will still be searched but as a
system directory at its normal position in the system include chain.
This is to ensure that GCC's procedure to fix buggy system headers and
the ordering for the include_next directive are not inadvertently changed.
If you really need to change the search order for system directories,
use the -nostdinc and/or -isystem options.
-iplugindir=dir-iquotedir-Ldir-BprefixThe compiler driver program runs one or more of the subprograms cpp, cc1, as and ld. It tries prefix as a prefix for each program it tries to run, both with and without ‘machine/version/’ (see Target Options).
For each subprogram to be run, the compiler driver first tries the -B prefix, if any. If that name is not found, or if -B was not specified, the driver tries two standard prefixes, /usr/lib/gcc/ and /usr/local/lib/gcc/. If neither of those results in a file name that is found, the unmodified program name is searched for using the directories specified in your PATH environment variable.
The compiler will check to see if the path provided by the -B refers to a directory, and if necessary it will add a directory separator character at the end of the path.
-B prefixes that effectively specify directory names also apply to libraries in the linker, because the compiler translates these options into -L options for the linker. They also apply to includes files in the preprocessor, because the compiler translates these options into -isystem options for the preprocessor. In this case, the compiler appends ‘include’ to the prefix.
The runtime support file libgcc.a can also be searched for using the -B prefix, if needed. If it is not found there, the two standard prefixes above are tried, and that is all. The file is left out of the link if it is not found by those means.
Another way to specify a prefix much like the -B prefix is to use the environment variable GCC_EXEC_PREFIX. See Environment Variables.
As a special kludge, if the path provided by -B is
[dir/]stageN/, where N is a number in the range 0 to
9, then it will be replaced by [dir/]include. This is to help
with boot-strapping the compiler.
-specs=file--sysroot=dirIf you use both this option and the -isysroot option, then the --sysroot option will apply to libraries, but the -isysroot option will apply to header files.
The GNU linker (beginning with version 2.16) has the necessary support
for this option. If your linker does not support this option, the
header file aspect of --sysroot will still work, but the
library aspect will not.
-I-If additional directories are specified with -I options after the -I-, these directories are searched for all ‘#include’ directives. (Ordinarily all -I directories are used this way.)
In addition, the -I- option inhibits the use of the current directory (where the current input file came from) as the first search directory for ‘#include "file"’. There is no way to override this effect of -I-. With -I. you can specify searching the directory that was current when the compiler was invoked. That is not exactly the same as what the preprocessor does by default, but it is often satisfactory.
-I- does not inhibit the use of the standard system directories for header files. Thus, -I- and -nostdinc are independent.
gcc is a driver program. It performs its job by invoking a sequence of other programs to do the work of compiling, assembling and linking. GCC interprets its command-line parameters and uses these to deduce which programs it should invoke, and which command-line options it ought to place on their command lines. This behavior is controlled by spec strings. In most cases there is one spec string for each program that GCC can invoke, but a few programs have multiple spec strings to control their behavior. The spec strings built into GCC can be overridden by using the -specs= command-line switch to specify a spec file.
Spec files are plaintext files that are used to construct spec strings. They consist of a sequence of directives separated by blank lines. The type of directive is determined by the first non-whitespace character on the line, which can be one of the following:
%command%include <file>%include_noerr <file>%rename old_name new_name*[spec_name]:[suffix]: .ZZ:
z-compile -input %i
This says that any input file whose name ends in ‘.ZZ’ should be passed to the program ‘z-compile’, which should be invoked with the command-line switch -input and with the result of performing the ‘%i’ substitution. (See below.)
As an alternative to providing a spec string, the text that follows a suffix directive can be one of the following:
@language .ZZ:
@c++
Says that .ZZ files are, in fact, C++ source files.
#namename compiler not installed on this system.
GCC already has an extensive list of suffixes built into it. This directive will add an entry to the end of the list of suffixes, but since the list is searched from the end backwards, it is effectively possible to override earlier entries using this technique.
GCC has the following spec strings built into it. Spec files can override these strings or create their own. Note that individual targets can also add their own spec strings to this list.
asm Options to pass to the assembler
asm_final Options to pass to the assembler post-processor
cpp Options to pass to the C preprocessor
cc1 Options to pass to the C compiler
cc1plus Options to pass to the C++ compiler
endfile Object files to include at the end of the link
link Options to pass to the linker
lib Libraries to include on the command line to the linker
libgcc Decides which GCC support library to pass to the linker
linker Sets the name of the linker
predefines Defines to be passed to the C preprocessor
signed_char Defines to pass to CPP to say whether char is signed
by default
startfile Object files to include at the start of the link
Here is a small example of a spec file:
%rename lib old_lib
*lib:
--start-group -lgcc -lc -leval1 --end-group %(old_lib)
This example renames the spec called ‘lib’ to ‘old_lib’ and then overrides the previous definition of ‘lib’ with a new one. The new definition adds in some extra command-line options before including the text of the old definition.
Spec strings are a list of command-line options to be passed to their corresponding program. In addition, the spec strings can contain ‘%’-prefixed sequences to substitute variable text or to conditionally insert text into the command line. Using these constructs it is possible to generate quite complex command lines.
Here is a table of all defined ‘%’-sequences for spec strings. Note that spaces are not generated automatically around the results of expanding these sequences. Therefore you can concatenate them together or combine them with constant text in a single argument.
%%%i%b%B%d%gsuffix%usuffix%Usuffix%jsuffixHOST_BIT_BUCKET, if any, and if it is
writable, and if save-temps is off; otherwise, substitute the name
of a temporary file, just like ‘%u’. This temporary file is not
meant for communication between processes, but rather as a junk
disposal mechanism.
%|suffix%msuffixX}’
construct: see for example f/lang-specs.h.
%.SUFFIX%w%o%O%pcpp.
%P%I%s%T%estr%(name)%x{option}%X%Y%Z%aasm spec. This is used to compute the
switches to be passed to the assembler.
%Aasm_final spec. This is a spec string for
passing switches to an assembler post-processor, if such a program is
needed.
%llink spec. This is the spec for computing the
command line passed to the linker. Typically it will make use of the
‘%L %G %S %D and %E’ sequences.
%D%Llib spec. This is a spec string for deciding which
libraries should be included on the command line to the linker.
%Glibgcc spec. This is a spec string for deciding
which GCC support library should be included on the command line to the linker.
%Sstartfile spec. This is a spec for deciding which
object files should be the first ones passed to the linker. Typically
this might be a file named crt0.o.
%Eendfile spec. This is a spec string that specifies
the last object files that will be passed to the linker.
%Ccpp spec. This is used to construct the arguments
to be passed to the C preprocessor.
%1cc1 spec. This is used to construct the options to be
passed to the actual C compiler (‘cc1’).
%2cc1plus spec. This is used to construct the options to be
passed to the actual C++ compiler (‘cc1plus’).
%*%<S-S from the command line. Note—this
command is position dependent. ‘%’ commands in the spec string
before this one will see -S, ‘%’ commands in the spec string
after this one will not.
%:function(args)The following built-in spec functions are provided:
getenvgetenv spec function takes two arguments: an environment
variable name and a string. If the environment variable is not
defined, a fatal error is issued. Otherwise, the return value is the
value of the environment variable concatenated with the string. For
example, if TOPDIR is defined as /path/to/top, then:
%:getenv(TOPDIR /include)
expands to /path/to/top/include.
if-existsif-exists spec function takes one argument, an absolute
pathname to a file. If the file exists, if-exists returns the
pathname. Here is a small example of its usage:
*startfile:
crt0%O%s %:if-exists(crti%O%s) crtbegin%O%s
if-exists-elseif-exists-else spec function is similar to the if-exists
spec function, except that it takes two arguments. The first argument is
an absolute pathname to a file. If the file exists, if-exists-else
returns the pathname. If it does not exist, it returns the second argument.
This way, if-exists-else can be used to select one file or another,
based on the existence of the first. Here is a small example of its usage:
*startfile:
crt0%O%s %:if-exists(crti%O%s) \
%:if-exists-else(crtbeginT%O%s crtbegin%O%s)
replace-outfilereplace-outfile spec function takes two arguments. It looks for the
first argument in the outfiles array and replaces it with the second argument. Here
is a small example of its usage:
%{fgnu-runtime:%:replace-outfile(-lobjc -lobjc-gnu)}
remove-outfileremove-outfile spec function takes one argument. It looks for the
first argument in the outfiles array and removes it. Here is a small example
its usage:
%:remove-outfile(-lm)
pass-through-libspass-through-libs spec function takes any number of arguments. It
finds any -l options and any non-options ending in ".a" (which it
assumes are the names of linker input library archive files) and returns a
result containing all the found arguments each prepended by
-plugin-opt=-pass-through= and joined by spaces. This list is
intended to be passed to the LTO linker plugin.
%:pass-through-libs(%G %L %G)
print-asm-headerprint-asm-header function takes no arguments and simply
prints a banner like:
Assembler options
=================
Use "-Wa,OPTION" to pass "OPTION" to the assembler.
It is used to separate compiler options from assembler options in the --target-help output.
%{S}-S switch, if that switch was given to GCC.
If that switch was not specified, this substitutes nothing. Note that
the leading dash is omitted when specifying this option, and it is
automatically inserted if the substitution is performed. Thus the spec
string ‘%{foo}’ would match the command-line option -foo
and would output the command-line option -foo.
%W{S}S} but mark last argument supplied within as a file to be
deleted on failure.
%{S*}-S, but which also take an argument. This is used for
switches like -o, -D, -I, etc.
GCC considers -o foo as being
one switch whose names starts with ‘o’. %{o*} would substitute this
text, including the space. Thus two arguments would be generated.
%{S*&T*}S*}, but preserve order of S and T options
(the order of S and T in the spec is not significant).
There can be any number of ampersand-separated variables; for each the
wild card is optional. Useful for CPP as ‘%{D*&U*&A*}’.
%{S:X}X, if the ‘-S’ switch was given to GCC.
%{!S:X}X, if the ‘-S’ switch was not given to GCC.
%{S*:X}X if one or more switches whose names start with
-S are specified to GCC. Normally X is substituted only
once, no matter how many such switches appeared. However, if %*
appears somewhere in X, then X will be substituted once
for each matching switch, with the %* replaced by the part of
that switch that matched the *.
%{.S:X}X, if processing a file with suffix S.
%{!.S:X}X, if not processing a file with suffix S.
%{,S:X}X, if processing a file for language S.
%{!,S:X}X, if not processing a file for language S.
%{S|P:X}X if either -S or -P was given to
GCC. This may be combined with ‘!’, ‘.’, ‘,’, and
* sequences as well, although they have a stronger binding than
the ‘|’. If %* appears in X, all of the
alternatives must be starred, and only the first matching alternative
is substituted.
For example, a spec string like this:
%{.c:-foo} %{!.c:-bar} %{.c|d:-baz} %{!.c|d:-boggle}
will output the following command-line options from the following input command-line options:
fred.c -foo -baz
jim.d -bar -boggle
-d fred.c -foo -baz -boggle
-d jim.d -bar -baz -boggle
%{S:X; T:Y; :D}S was given to GCC, substitutes X; else if T was
given to GCC, substitutes Y; else substitutes D. There can
be as many clauses as you need. This may be combined with .,
,, !, |, and * as needed.
The conditional text X in a %{S:X} or similar
construct may contain other nested ‘%’ constructs or spaces, or
even newlines. They are processed as usual, as described above.
Trailing white space in X is ignored. White space may also
appear anywhere on the left side of the colon in these constructs,
except between . or * and the corresponding word.
The -O, -f, -m, and -W switches are
handled specifically in these constructs. If another value of
-O or the negated form of a -f, -m, or
-W switch is found later in the command line, the earlier
switch value is ignored, except with {S*} where S is
just one letter, which passes all matching options.
The character ‘|’ at the beginning of the predicate text is used to indicate that a command should be piped to the following command, but only if -pipe is specified.
It is built into GCC which switches take arguments and which do not. (You might think it would be useful to generalize this to allow each compiler's spec to say which switches take arguments. But this cannot be done in a consistent fashion. GCC cannot even decide which input files have been specified without knowing which switches take arguments, and it must know which input files to compile in order to tell which compilers to run).
GCC also knows implicitly that arguments starting in -l are to be treated as compiler output files, and passed to the linker in their proper position among the other output files.
The usual way to run GCC is to run the executable called gcc, or machine-gcc when cross-compiling, or machine-gcc-version to run a version other than the one that was installed last.
Each target machine types can have its own special options, starting with ‘-m’, to choose among various hardware models or configurations—for example, 68010 vs 68020, floating coprocessor or none. A single installed version of the compiler can compile for any model or configuration, according to the options specified.
Some configurations of the compiler also support additional special options, usually for compatibility with other compilers on the same platform.
These ‘-m’ options are defined for Adapteva Epiphany:
-mhalf-reg-filer32...r63.
That allows code to run on hardware variants that lack these registers.
-mprefer-short-insn-regs-mbranch-cost=num-mcmove-mnops=num-mno-soft-cmpsf-mstack-offset=num-mno-round-nearest-mlong-calls-mshort-calls-msmall16-mfp-mode=modemode can be set to one the following values:
The default is -mfp-mode=caller
-mnosplit-lohi-mno-postinc-mno-postmodify-mnovect-double-max-vect-align=num-msplit-vecmove-early-m1reg-regThese ‘-m’ options are defined for Advanced RISC Machines (ARM) architectures:
-mabi=name-mapcs-frame-mapcs-mthumb-interwork-mno-sched-prolog-mfloat-abi=nameSpecifying ‘soft’ causes GCC to generate output containing library calls for floating-point operations. ‘softfp’ allows the generation of code using hardware floating-point instructions, but still uses the soft-float calling conventions. ‘hard’ allows generation of floating-point instructions and uses FPU-specific calling conventions.
The default depends on the specific target configuration. Note that
the hard-float and soft-float ABIs are not link-compatible; you must
compile your entire program with the same ABI, and link with a
compatible set of libraries.
-mlittle-endian-mbig-endian-mwords-little-endian-mcpu=name-mcpu=generic-arch is also permissible, and is equivalent to -march=arch -mtune=generic-arch. See -mtune for more information.
-mcpu=native causes the compiler to auto-detect the CPU
of the build computer. At present, this feature is only supported on
Linux, and not all architectures are recognized. If the auto-detect is
unsuccessful the option has no effect.
-mtune=name-mtune=generic-arch specifies that GCC should tune the performance for a blend of processors within architecture arch. The aim is to generate code that run well on the current most popular processors, balancing between optimizations that benefit some CPUs in the range, and avoiding performance pitfalls of other CPUs. The effects of this option may change in future GCC versions as CPU models come and go.
-mtune=native causes the compiler to auto-detect the CPU
of the build computer. At present, this feature is only supported on
Linux, and not all architectures are recognized. If the auto-detect is
unsuccessful the option has no effect.
-march=name-march=native causes the compiler to auto-detect the architecture
of the build computer. At present, this feature is only supported on
Linux, and not all architectures are recognized. If the auto-detect is
unsuccessful the option has no effect.
-mfpu=name-mfpe=number-mfp=numberIf -msoft-float is specified this specifies the format of floating-point values.
If the selected floating-point hardware includes the NEON extension
(e.g. -mfpu=‘neon’), note that floating-point
operations will not be used by GCC's auto-vectorization pass unless
-funsafe-math-optimizations is also specified. This is
because NEON hardware does not fully implement the IEEE 754 standard for
floating-point arithmetic (in particular denormal values are treated as
zero), so the use of NEON instructions may lead to a loss of precision.
-mfp16-format=name__fp16 half-precision floating-point type.
Permissible names are ‘none’, ‘ieee’, and ‘alternative’;
the default is ‘none’, in which case the __fp16 type is not
defined. See Half-Precision, for more information.
-mstructure-size-boundary=nSpecifying the larger number can produce faster, more efficient code, but
can also increase the size of the program. Different values are potentially
incompatible. Code compiled with one value cannot necessarily expect to
work with code or libraries compiled with another value, if they exchange
information using structures or unions.
-mabort-on-noreturnabort at the end of a
noreturn function. It will be executed if the function tries to
return.
-mlong-calls-mno-long-callsEven if this switch is enabled, not all function calls will be turned into long calls. The heuristic is that static functions, functions that have the ‘short-call’ attribute, functions that are inside the scope of a ‘#pragma no_long_calls’ directive and functions whose definitions have already been compiled within the current compilation unit, will not be turned into long calls. The exception to this rule is that weak function definitions, functions with the ‘long-call’ attribute or the ‘section’ attribute, and functions that are within the scope of a ‘#pragma long_calls’ directive, will always be turned into long calls.
This feature is not enabled by default. Specifying
-mno-long-calls will restore the default behavior, as will
placing the function calls within the scope of a ‘#pragma
long_calls_off’ directive. Note these switches have no effect on how
the compiler generates code to handle function calls via function
pointers.
-msingle-pic-base-mpic-register=reg-mcirrus-fix-invalid-insns-mpoke-function-name t0
.ascii "arm_poke_function_name", 0
.align
t1
.word 0xff000000 + (t1 - t0)
arm_poke_function_name
mov ip, sp
stmfd sp!, {fp, ip, lr, pc}
sub fp, ip, #4
When performing a stack backtrace, code can inspect the value of
pc stored at fp + 0. If the trace function then looks at
location pc - 12 and the top 8 bits are set, then we know that
there is a function name embedded immediately preceding this location
and has length ((pc[-3]) & 0xff000000).
-mthumb-marm-mtpcs-frame-mtpcs-leaf-frame-mcallee-super-interworking-mcaller-super-interworking-mtp=name__aeabi_read_tp,
cp15, which fetches the thread pointer from cp15 directly
(supported in the arm6k architecture), and auto, which uses the
best available method for the selected processor. The default setting is
auto.
-mtls-dialect=dialect-mword-relocations-mfix-cortex-m3-ldrdldrd instructions
with overlapping destination and base registers are used. This option avoids
generating these instructions. This option is enabled by default when
-mcpu=cortex-m3 is specified.
-munaligned-access-mno-unaligned-accessThe ARM attribute Tag_CPU_unaligned_access will be set in the
generated object file to either true or false, depending upon the
setting of this option. If unaligned access is enabled then the
preprocessor symbol __ARM_FEATURE_UNALIGNED will also be
defined.
-mmcu=mcuFor a complete list of mcu values that are supported by avr-gcc,
see the compiler output when called with the --help=target
command line option.
The default for this option is avr2.
GCC supports the following AVR devices and ISAs:
avr2at90c8534, at90s2313,
at90s2323, at90s2333, at90s2343,
at90s4414, at90s4433, at90s4434,
at90s8515, at90s8535, attiny22, attiny26.
avr25MOVW instruction.
at86rf401, ata6289, attiny13,
attiny13a, attiny2313, attiny2313a,
attiny24, attiny24a, attiny25, attiny261,
attiny261a, attiny4313, attiny43u,
attiny44, attiny44a, attiny45, attiny461,
attiny461a, attiny48, attiny84, attiny84a,
attiny85, attiny861, attiny861a, attiny87,
attiny88.
avr3at43usb355, at76c711.
avr31at43usb320, atmega103.
avr35MOVW instruction.
at90usb162, at90usb82,
atmega16u2, atmega32u2, atmega8u2,
attiny167.
avr4at90pwm1, at90pwm2, at90pwm2b,
at90pwm3, at90pwm3b, at90pwm81, atmega48,
atmega48a, atmega48p, atmega8, atmega8515,
atmega8535, atmega88, atmega88a,
atmega88p, atmega88pa, atmega8hva.
avr5at90can32, at90can64,
at90pwm216, at90pwm316, at90scr100,
at90usb646, at90usb647, at94k, atmega16,
atmega161, atmega162, atmega163,
atmega164a, atmega164p, atmega165,
atmega165a, atmega165p, atmega168,
atmega168a, atmega168p, atmega169,
atmega169a, atmega169p, atmega169pa,
atmega16a, atmega16hva, atmega16hva2,
atmega16hvb, atmega16m1, atmega16u4,
atmega32, atmega323, atmega324a,
atmega324p, atmega324pa, atmega325,
atmega3250, atmega3250a, atmega3250p,
atmega325a, atmega325p, atmega328,
atmega328p, atmega329, atmega3290,
atmega3290a, atmega3290p, atmega329a,
atmega329p, atmega329pa, atmega32c1,
atmega32hvb, atmega32m1, atmega32u4,
atmega32u6, atmega406, atmega64,
atmega640, atmega644, atmega644a,
atmega644p, atmega644pa, atmega645,
atmega6450, atmega6450a, atmega6450p,
atmega645a, atmega645p, atmega649,
atmega6490, atmega649a, atmega649p,
atmega64c1, atmega64hve, atmega64m1,
m3000.
avr51at90can128, at90usb1286,
at90usb1287, atmega128, atmega1280,
atmega1281, atmega1284p, atmega128rfa1.
avr6atmega2560, atmega2561.
avrxmega2atxmega16a4, atxmega16d4,
atxmega16x1, atxmega32a4, atxmega32d4,
atxmega32x1.
avrxmega4atxmega64a3, atxmega64d3.
avrxmega5atxmega64a1, atxmega64a1u.
avrxmega6atxmega128a3, atxmega128d3,
atxmega192a3, atxmega192d3, atxmega256a3,
atxmega256a3b, atxmega256a3bu, atxmega256d3.
avrxmega7atxmega128a1, atxmega128a1u.
avr1at90s1200, attiny11, attiny12,
attiny15, attiny28.
-maccumulate-argsPopping the arguments after the function call can be expensive on AVR so that accumulating the stack space might lead to smaller executables because arguments need not to be removed from the stack after such a function call.
This option can lead to reduced code size for functions that perform
several calls to functions that get their arguments on the stack like
calls to printf-like functions.
-mbranch-cost=cost-mcall-prologues-mint8int to be 8-bit integer. This affects the sizes of all types: a
char is 1 byte, an int is 1 byte, a long is 2 bytes,
and long long is 4 bytes. Please note that this option does not
conform to the C standards, but it results in smaller code
size.
-mno-interrupts-mrelaxCALL resp. JMP instruction by the shorter
RCALL resp. RJMP instruction if applicable.
Setting -mrelax just adds the --relax option to the
linker command line when the linker is called.
Jump relaxing is performed by the linker because jump offsets are not known before code is located. Therefore, the assembler code generated by the compiler is the same, but the instructions in the executable may differ from instructions in the assembler code.
Relaxing must be turned on if linker stubs are needed, see the
section on EIND and linker stubs below.
-mshort-callsRCALL/RJMP instructions even on devices with
16 KiB or more of program memory, i.e. on devices that
have the CALL and JMP instructions.
See also the -mrelax command line option.
-msp8This option is used internally by the compiler to select and
build multilibs for architectures avr2 and avr25.
These architectures mix devices with and without SPH.
For any setting other than -mmcu=avr2 or -mmcu=avr25
the compiler driver will add or remove this option from the compiler
proper's command line, because the compiler then knows if the device
or architecture has an 8-bit stack pointer and thus no SPH
register or not.
-mstrict-XX in a way proposed by the hardware. This means
that X is only used in indirect, post-increment or
pre-decrement addressing.
Without this option, the X register may be used in the same way
as Y or Z which then is emulated by additional
instructions.
For example, loading a value with X+const addressing with a
small non-negative const < 64 to a register Rn is
performed as
adiw r26, const ; X += const
ld Rn, X ; Rn = *X
sbiw r26, const ; X -= const
-mtiny-stackEIND and Devices with more than 128 Ki Bytes of FlashPointers in the implementation are 16 bits wide. The address of a function or label is represented as word address so that indirect jumps and calls can target any code address in the range of 64 Ki words.
In order to facilitate indirect jump on devices with more than 128 Ki
bytes of program memory space, there is a special function register called
EIND that serves as most significant part of the target address
when EICALL or EIJMP instructions are used.
Indirect jumps and calls on these devices are handled as follows by the compiler and are subject to some limitations:
EIND.
EIND implicitely in EICALL/EIJMP
instructions or might read EIND directly in order to emulate an
indirect call/jump by means of a RET instruction.
EIND never changes during the startup
code or during the application. In particular, EIND is not
saved/restored in function or interrupt service routine
prologue/epilogue.
-mrelax and the linler option --relax.
There are corner cases where the linker is supposed to generate stubs
but aborts without relaxation and without a helpful error message.
EIND = 0.
If code is supposed to work for a setup with EIND != 0, a custom
linker script has to be used in order to place the sections whose
name start with .trampolines into the segment where EIND
points to.
EIND.
Notice that startup code is a blend of code from libgcc and AVR-LibC.
For the impact of AVR-LibC on EIND, see the
AVR-LibC user manual.
EIND
early, for example by means of initialization code located in
section .init3. Such code runs prior to general startup code
that initializes RAM and calls constructors, but after the bit
of startup code from AVR-LibC that sets EIND to the segment
where the vector table is located.
#include <avr/io.h>
static void
__attribute__((section(".init3"),naked,used,no_instrument_function))
init3_set_eind (void)
{
__asm volatile ("ldi r24,pm_hh8(__trampolines_start)\n\t"
"out %i0,r24" :: "n" (&EIND) : "r24","memory");
}
The __trampolines_start symbol is defined in the linker script.
gs modifier
(short for generate stubs) like so:
LDI r24, lo8(gs(func))
LDI r25, hi8(gs(func))
gs modifiers for code labels in the
following situations:
gs() modifier explained above.
int main (void)
{
/* Call function at word address 0x2 */
return ((int(*)(void)) 0x2)();
}
Instead, a stub has to be set up, i.e. the function has to be called
through a symbol (func_4 in the example):
int main (void)
{
extern int func_4 (void);
/* Call function at byte address 0x4 */
return func_4();
}
and the application be linked with -Wl,--defsym,func_4=0x4.
Alternatively, func_4 can be defined in the linker script.
RAMPD, RAMPX, RAMPY and RAMPZ Special Function RegistersSome AVR devices support memories larger than the 64 KiB range
that can be accessed with 16-bit pointers. To access memory locations
outside this 64 KiB range, the contentent of a RAMP
register is used as high part of the address:
The X, Y, Z address register is concatenated
with the RAMPX, RAMPY, RAMPZ special function
register, respectively, to get a wide address. Similarly,
RAMPD is used together with direct addressing.
RAMP special function
registers with zero.
__flash is used, then RAMPZ is set
as needed before the operation.
RAMPZ to accomplish an operation, RAMPZ
is reset to zero after the operation.
RAMP register, the ISR
prologue/epilogue saves/restores that SFR and initializes it with
zero in case the ISR code might (implicitly) use it.
RAMP registers,
you must reset it to zero after the access.
GCC defines several built-in macros so that the user code can test
for the presence or absence of features. Almost any of the following
built-in macros are deduced from device capabilities and thus
triggered by the -mmcu= command-line option.
For even more AVR-specific built-in macros see AVR Named Address Spaces and AVR Built-in Functions.
__AVR_Device__-mmcu=device defines this built-in macro which reflects
the device's name. For example, -mmcu=atmega8 defines the
built-in macro __AVR_ATmega8__, -mmcu=attiny261a defines
__AVR_ATtiny261A__, etc.
The built-in macros' names follow
the scheme __AVR_Device__ where Device is
the device name as from the AVR user manual. The difference between
Device in the built-in macro and device in
-mmcu=device is that the latter is always lowercase.
__AVR_HAVE_ELPM__ELPM instruction.
__AVR_HAVE_ELPMX__ELPM Rn,Z and ELPM
Rn,Z+ instructions.
__AVR_HAVE_MOVW__MOVW instruction to perform 16-bit
register-register moves.
__AVR_HAVE_LPMX__LPM Rn,Z and
LPM Rn,Z+ instructions.
__AVR_HAVE_MUL____AVR_HAVE_JMP_CALL__JMP and CALL instructions.
This is the case for devices with at least 16 KiB of program
memory and if -mshort-calls is not set.
__AVR_HAVE_EIJMP_EICALL____AVR_3_BYTE_PC__EIJMP and EICALL instructions.
This is the case for devices with more than 128 KiB of program memory.
This also means that the program counter
(PC) is 3 bytes wide.
__AVR_2_BYTE_PC____AVR_HAVE_8BIT_SP____AVR_HAVE_16BIT_SP__-mtiny-stack.
__AVR_HAVE_SPH____AVR_SP8__-mmcu= and
in the cases of -mmcu=avr2 and -mmcu=avr25 also
by -msp8.
__AVR_HAVE_RAMPD____AVR_HAVE_RAMPX____AVR_HAVE_RAMPY____AVR_HAVE_RAMPZ__RAMPD, RAMPX, RAMPY,
RAMPZ special function register, respectively.
__NO_INTERRUPTS__-mno-interrupts command line option.
__AVR_ERRATA_SKIP____AVR_ERRATA_SKIP_JMP_CALL__SBRS, SBRC, SBIS, SBIC and CPSE.
The second macro is only defined if __AVR_HAVE_JMP_CALL__ is also
set.
__AVR_SFR_OFFSET__=offsetIN, OUT, SBI, etc. may use a different
address as if addressed by an instruction to access RAM like LD
or STS. This offset depends on the device architecture and has
to be subtracted from the RAM address in order to get the
respective I/O address.
__WITH_AVRLIBC__--with-avrlibc configure option.
-mcpu=cpu[-sirevision]__SILICON_REVISION__ macro is defined to two
hexadecimal digits representing the major and minor numbers in the silicon
revision. If sirevision is ‘none’, the __SILICON_REVISION__
is not defined. If sirevision is ‘any’, the
__SILICON_REVISION__ is defined to be 0xffff.
If this optional sirevision is not used, GCC assumes the latest known
silicon revision of the targeted Blackfin processor.
Support for ‘bf561’ is incomplete. For ‘bf561’,
Only the processor macro is defined.
Without this option, ‘bf532’ is used as the processor by default.
The corresponding predefined processor macros for cpu is to
be defined. And for ‘bfin-elf’ toolchain, this causes the hardware BSP
provided by libgloss to be linked in if -msim is not given.
-msim-momit-leaf-frame-pointer-mspecld-anomaly__WORKAROUND_SPECULATIVE_LOADS is defined.
-mno-specld-anomaly-mcsync-anomaly__WORKAROUND_SPECULATIVE_SYNCS is defined.
-mno-csync-anomaly-mlow-64k-mno-low-64k-mstack-check-l1-mid-shared-library-mno-id-shared-library-mleaf-id-shared-library-mno-leaf-id-shared-library-mshared-library-id=n-msep-data-mno-sep-data-mlong-calls-mno-long-callsThis feature is not enabled by default. Specifying
-mno-long-calls will restore the default behavior. Note these
switches have no effect on how the compiler generates code to handle
function calls via function pointers.
-mfast-fp-minline-plt-mmulticore__BFIN_MULTICORE. It can only be used with
-mcpu=bf561[-sirevision]. It can be used with
-mcorea or -mcoreb. If it's used without
-mcorea or -mcoreb, single application/dual core
programming model is used. In this model, the main function of Core B
should be named as coreb_main. If it's used with -mcorea or
-mcoreb, one application per core programming model is used.
If this option is not used, single core application programming
model is used.
-mcorea__BFIN_COREA. It must be used with -mmulticore.
-mcoreb__BFIN_COREB. When this option is used, coreb_main
should be used instead of main. It must be used with
-mmulticore.
-msdram__BFIN_SDRAM.
-micplb-march=name-mbig-endian-mlittle-endian-msim-msdata=defaultB14. Put small uninitialized
global and static data in the ‘.bss’ section, which is adjacent
to the ‘.neardata’ section. Put small read-only data into the
‘.rodata’ section. The corresponding sections used for large
pieces of data are ‘.fardata’, ‘.far’ and ‘.const’.
-msdata=allB14 register to
access them.
-msdata=noneThese options are defined specifically for the CRIS ports.
-march=architecture-type-mcpu=architecture-type-mtune=architecture-type-mmax-stack-frame=n-metrax4-metrax100-mmul-bug-workaround-mno-mul-bug-workaroundmuls and mulu instructions for CPU
models where it applies. This option is active by default.
-mpdebug-mcc-init-mno-side-effects-mstack-align-mno-stack-align-mdata-align-mno-data-align-mconst-align-mno-const-align-m32-bit-m16-bit-m8-bit-mno-prologue-epilogue-mprologue-epilogue-mno-gotplt-mgotplt-melf-mlinux-sim-sim2These options are defined specifically for the CR16 ports.
-mmac-mcr16cplus-mcr16c-msim-mint32-mbit-ops-mdata-model=modelThese options are defined for all architectures running the Darwin operating system.
FSF GCC on Darwin does not create “fat” object files; it will create an object file for the single architecture that it was built to target. Apple's GCC on Darwin does create “fat” files if multiple -arch options are used; it does so by running the compiler or linker multiple times and joining the results together with lipo.
The subtype of the file created (like ‘ppc7400’ or ‘ppc970’ or ‘i686’) is determined by the flags that specify the ISA that GCC is targetting, like -mcpu or -march. The -force_cpusubtype_ALL option can be used to override this.
The Darwin tools vary in their behavior when presented with an ISA mismatch. The assembler, as, will only permit instructions to be used that are valid for the subtype of the file it is generating, so you cannot put 64-bit instructions in a ‘ppc750’ object file. The linker for shared libraries, /usr/bin/libtool, will fail and print an error if asked to create a shared library with a less restrictive subtype than its input files (for instance, trying to put a ‘ppc970’ object file in a ‘ppc7400’ library). The linker for executables, ld, will quietly give the executable the most restrictive subtype of any of its input files.
-FdirA framework directory is a directory with frameworks in it. A
framework is a directory with a ‘"Headers"’ and/or
‘"PrivateHeaders"’ directory contained directly in it that ends
in ‘".framework"’. The name of a framework is the name of this
directory excluding the ‘".framework"’. Headers associated with
the framework are found in one of those two directories, with
‘"Headers"’ being searched first. A subframework is a framework
directory that is in a framework's ‘"Frameworks"’ directory.
Includes of subframework headers can only appear in a header of a
framework that contains the subframework, or in a sibling subframework
header. Two subframeworks are siblings if they occur in the same
framework. A subframework should not have the same name as a
framework, a warning will be issued if this is violated. Currently a
subframework cannot have subframeworks, in the future, the mechanism
may be extended to support this. The standard frameworks can be found
in ‘"/System/Library/Frameworks"’ and
‘"/Library/Frameworks"’. An example include looks like
#include <Framework/header.h>, where ‘Framework’ denotes
the name of the framework and header.h is found in the
‘"PrivateHeaders"’ or ‘"Headers"’ directory.
-iframeworkdir-gused-gfull-mmacosx-version-min=version10.1,
10.2, and 10.3.9.
If the compiler was built to use the system's headers by default,
then the default for this option is the system version on which the
compiler is running, otherwise the default is to make choices that
are compatible with as many systems and code bases as possible.
-mkernel-mone-byte-boolWarning: The -mone-byte-bool switch causes GCC
to generate code that is not binary compatible with code generated
without that switch. Using this switch may require recompiling all
other modules in a program, including system libraries. Use this
switch to conform to a non-default data model.
-mfix-and-continue-ffix-and-continue-findirect-data.o files into already running
programs. -findirect-data and -ffix-and-continue
are provided for backwards compatibility.
-all_load-arch_errors_fatal-bind_at_load-bundle-bundle_loader executable-dynamiclib-force_cpusubtype_ALL-allowable_client client_name-client_name-compatibility_version-current_version-dead_strip-dependency-file-dylib_file-dylinker_install_name-dynamic-exported_symbols_list-filelist-flat_namespace-force_flat_namespace-headerpad_max_install_names-image_base-init-install_name-keep_private_externs-multi_module-multiply_defined-multiply_defined_unused-noall_load-no_dead_strip_inits_and_terms-nofixprebinding-nomultidefs-noprebind-noseglinkedit-pagezero_size-prebind-prebind_all_twolevel_modules-private_bundle-read_only_relocs-sectalign-sectobjectsymbols-whyload-seg1addr-sectcreate-sectobjectsymbols-sectorder-segaddr-segs_read_only_addr-segs_read_write_addr-seg_addr_table-seg_addr_table_filename-seglinkedit-segprot-segs_read_only_addr-segs_read_write_addr-single_module-static-sub_library-sub_umbrella-twolevel_namespace-umbrella-undefined-unexported_symbols_list-weak_reference_mismatches-whatsloadedThese ‘-m’ options are defined for the DEC Alpha implementations:
-mno-soft-float-msoft-floatNote that Alpha implementations without floating-point operations are
required to have floating-point registers.
-mfp-reg-mno-fp-regs$0 instead of $f0. This is a non-standard calling sequence,
so any function with a floating-point argument or return value called by code
compiled with -mno-fp-regs must also be compiled with that
option.
A typical use of this option is building a kernel that does not use,
and hence need not save and restore, any floating-point registers.
-mieee_IEEE_FP is
defined during compilation. The resulting code is less efficient but is
able to correctly support denormalized numbers and exceptional IEEE
values such as not-a-number and plus/minus infinity. Other Alpha
compilers call this option -ieee_with_no_inexact.
DEBIAN SPECIFIC: (only for alpha architecture) This option is on by default, unless
-ffinite-math-only (which is part of the -ffast-math
set) is specified, because the software functions in the GNU libc math
libraries generate denormalized numbers, NaNs, and infs (all of which
will cause a programs to SIGFPE when it attempts to use the results without
-mieee).
-mieee-with-inexact_IEEE_FP, _IEEE_FP_EXACT is defined as a preprocessor
macro. On some Alpha implementations the resulting code may execute
significantly slower than the code generated by default. Since there is
very little code that depends on the inexact-flag, you should
normally not specify this option. Other Alpha compilers call this
option -ieee_with_inexact.
-mfp-trap-mode=trap-mode-mfp-rounding-mode=rounding-mode-mtrap-precision=trap-precisionOther Alpha compilers provide the equivalent options called
-scope_safe and -resumption_safe.
-mieee-conformant-mbuild-constantsUse this option to require GCC to construct all integer constants using code, even if it takes more instructions (the maximum is six).
You would typically use this option to build a shared library dynamic
loader. Itself a shared library, it must relocate itself in memory
before it can find the variables and constants in its own data segment.
-malpha-as-mgas-mbwx-mno-bwx-mcix-mno-cix-mfix-mno-fix-mmax-mno-max-mfloat-vax-mfloat-ieee-mexplicit-relocs-mno-explicit-relocs-msmall-data-mlarge-data.sdata and .sbss sections) and are accessed via
16-bit relocations off of the $gp register. This limits the
size of the small data area to 64KB, but allows the variables to be
directly accessed via a single instruction.
The default is -mlarge-data. With this option the data area
is limited to just below 2GB. Programs that require more than 2GB of
data must use malloc or mmap to allocate the data in the
heap instead of in the program's data segment.
When generating code for shared libraries, -fpic implies
-msmall-data and -fPIC implies -mlarge-data.
-msmall-text-mlarge-text$gp value, and thus reduce the number of instructions
required for a function call from 4 to 1.
The default is -mlarge-text.
-mcpu=cpu_typeSupported values for cpu_type are
Native toolchains also support the value ‘native’,
which selects the best architecture option for the host processor.
-mcpu=native has no effect if GCC does not recognize
the processor.
-mtune=cpu_typeNative toolchains also support the value ‘native’,
which selects the best architecture option for the host processor.
-mtune=native has no effect if GCC does not recognize
the processor.
-mmemory-latency=timeValid options for time are
These ‘-m’ options are defined for the DEC Alpha/VMS implementations:
-mvms-return-codes-mdebug-main=prefix-mmalloc64These options are defined specifically for the FR30 port.
-msmall-model-mno-lsim-mgpr-32-mgpr-64-mfpr-32-mfpr-64-mhard-float-msoft-float-malloc-cc-mfixed-ccicc0 and fcc0.
-mdword-mno-dword-mdouble-mno-double-mmedia-mno-media-mmuladd-mno-muladd-mfdpic-minline-plt-mTLS-mtls-mgprel-roGPREL relocations in the FDPIC ABI for data
that is known to be in read-only sections. It's enabled by default,
except for -fpic or -fpie: even though it may help
make the global offset table smaller, it trades 1 instruction for 4.
With -fPIC or -fPIE, it trades 3 instructions for 4,
one of which may be shared by multiple symbols, and it avoids the need
for a GOT entry for the referenced symbol, so it's more likely to be a
win. If it is not, -mno-gprel-ro can be used to disable it.
-multilib-library-pic-mlinked-fp-mlong-calls-malign-labels-mlibrary-pic-macc-4-macc-8-mpack-mno-pack-mno-eflags-mcond-moveThis switch is mainly for debugging the compiler and will likely be removed
in a future version.
-mno-cond-moveThis switch is mainly for debugging the compiler and will likely be removed
in a future version.
-msccThis switch is mainly for debugging the compiler and will likely be removed
in a future version.
-mno-sccThis switch is mainly for debugging the compiler and will likely be removed
in a future version.
-mcond-execThis switch is mainly for debugging the compiler and will likely be removed
in a future version.
-mno-cond-execThis switch is mainly for debugging the compiler and will likely be removed
in a future version.
-mvliw-branchThis switch is mainly for debugging the compiler and will likely be removed
in a future version.
-mno-vliw-branchThis switch is mainly for debugging the compiler and will likely be removed
in a future version.
-mmulti-cond-exec&& and || in conditional execution
(default).
This switch is mainly for debugging the compiler and will likely be removed
in a future version.
-mno-multi-cond-exec&& and || in conditional execution.
This switch is mainly for debugging the compiler and will likely be removed
in a future version.
-mnested-cond-execThis switch is mainly for debugging the compiler and will likely be removed
in a future version.
-mno-nested-cond-execThis switch is mainly for debugging the compiler and will likely be removed
in a future version.
-moptimize-membarmembar instructions from the
compiler generated code. It is enabled by default.
-mno-optimize-membarmembar
instructions from the generated code.
-mtomcat-stats-mcpu=cpuThese ‘-m’ options are defined for GNU/Linux targets:
-mglibc-muclibc-mbionic-mandroidWhen compiling, this option enables -mbionic, -fPIC,
-fno-exceptions and -fno-rtti by default. When linking,
this option makes the GCC driver pass Android-specific options to the linker.
Finally, this option causes the preprocessor macro __ANDROID__
to be defined.
-tno-android-cc-tno-android-ldThese ‘-m’ options are defined for the H8/300 implementations:
-mrelaxld and the H8/300, for a fuller description.
-mh-ms-mn-ms2600-mint32int data 32 bits by default.
-malign-300These ‘-m’ options are defined for the HPPA family of computers:
-march=architecture-type-mpa-risc-1-0-mpa-risc-1-1-mpa-risc-2-0-mbig-switch-mjump-in-delay-mdisable-fpregs-mdisable-indexing-mno-space-regsSuch code is suitable for level 0 PA systems and kernels.
-mfast-indirect-callsThis option will not work in the presence of shared libraries or nested
functions.
-mfixed-range=register-range-mlong-load-store-mportable-runtime-mgas-mschedule=cpu-type-mlinker-opt-msoft-float-msoft-float changes the calling convention in the output file;
therefore, it is only useful if you compile all of a program with
this option. In particular, you need to compile libgcc.a, the
library that comes with GCC, with -msoft-float in order for
this to work.
-msio_SIO, for server IO. The default is
-mwsio. This generates the predefines, __hp9000s700,
__hp9000s700__ and _WSIO, for workstation IO. These
options are available under HP-UX and HI-UX.
-mgnu-ld-mhp-ld-mlong-callsDistances are measured from the beginning of functions when using the -ffunction-sections option, or when using the -mgas and -mno-portable-runtime options together under HP-UX with the SOM linker.
It is normally not desirable to use this option as it will degrade performance. However, it may be useful in large applications, particularly when partial linking is used to build the application.
The types of long calls used depends on the capabilities of the
assembler and linker, and the type of code being generated. The
impact on systems that support long absolute calls, and long pic
symbol-difference or pc-relative calls should be relatively small.
However, an indirect call is used on 32-bit ELF systems in pic code
and it is quite long.
-munix=unix-std-munix=93 provides the same predefines as GCC 3.3 and 3.4.
-munix=95 provides additional predefines for XOPEN_UNIX
and _XOPEN_SOURCE_EXTENDED, and the startfile unix95.o.
-munix=98 provides additional predefines for _XOPEN_UNIX,
_XOPEN_SOURCE_EXTENDED, _INCLUDE__STDC_A1_SOURCE and
_INCLUDE_XOPEN_SOURCE_500, and the startfile unix98.o.
It is important to note that this option changes the interfaces for various library routines. It also affects the operational behavior of the C library. Thus, extreme care is needed in using this option.
Library code that is intended to operate with more than one UNIX
standard must test, set and restore the variable __xpg4_extended_mask
as appropriate. Most GNU software doesn't provide this capability.
-nolibdld-staticOn HP-UX 10 and later, the GCC driver adds the necessary options to
link with libdld.sl when the -static option is specified.
This causes the resulting binary to be dynamic. On the 64-bit port,
the linkers generate dynamic binaries by default in any case. The
-nolibdld option can be used to prevent the GCC driver from
adding these link options.
-threadsThese ‘-m’ options are defined for the i386 and x86-64 family of computers:
-mtune=cpu-typeAs new processors are deployed in the marketplace, the behavior of this option will change. Therefore, if you upgrade to a newer version of GCC, the code generated option will change to reflect the processors that were most common when that version of GCC was released.
There is no -march=generic option because -march
indicates the instruction set the compiler can use, and there is no
generic instruction set applicable to all processors. In contrast,
-mtune indicates the processor (or, in this case, collection of
processors) for which the code is optimized.
generic, but when used as march option, PentiumPro
instruction set will be used, so the code will run on all i686 family chips.
While picking a specific cpu-type will schedule things appropriately
for that particular chip, the compiler will not generate any code that
does not run on the default machine type without the -march=cpu-type
option being used. For example, if GCC is configured for i686-pc-linux-gnu
then -mtune=pentium4 will generate code that is tuned for Pentium4
but will still run on i686 machines.
-march=cpu-type-mcpu=cpu-type-mfpmath=unitThis is the default choice for i386 compiler.
For the i386 compiler, you need to use -march=cpu-type, -msse or -msse2 switches to enable SSE extensions and make this option effective. For the x86-64 compiler, these extensions are enabled by default.
The resulting code should be considerably faster in the majority of cases and avoid the numerical instability problems of 387 code, but may break some existing code that expects temporaries to be 80 bits.
This is the default choice for the x86-64 compiler.
-masm=dialect-mieee-fp-mno-ieee-fp-msoft-floatOn machines where a function returns floating-point results in the 80387
register stack, some floating-point opcodes may be emitted even if
-msoft-float is used.
-mno-fp-ret-in-387The usual calling convention has functions return values of types
float and double in an FPU register, even if there
is no FPU. The idea is that the operating system should emulate
an FPU.
The option -mno-fp-ret-in-387 causes such values to be returned
in ordinary CPU registers instead.
-mno-fancy-math-387sin, cos and
sqrt instructions for the 387. Specify this option to avoid
generating those instructions. This option is the default on FreeBSD,
OpenBSD and NetBSD. This option is overridden when -march
indicates that the target CPU will always have an FPU and so the
instruction will not need emulation. As of revision 2.6.1, these
instructions are not generated unless you also use the
-funsafe-math-optimizations switch.
-malign-double-mno-align-doubledouble, long double, and
long long variables on a two-word boundary or a one-word
boundary. Aligning double variables on a two-word boundary
produces code that runs somewhat faster on a ‘Pentium’ at the
expense of more memory.
On x86-64, -malign-double is enabled by default.
Warning: if you use the -malign-double switch,
structures containing the above types will be aligned differently than
the published application binary interface specifications for the 386
and will not be binary compatible with structures in code compiled
without that switch.
-m96bit-long-double-m128bit-long-doublelong double type. The i386
application binary interface specifies the size to be 96 bits,
so -m96bit-long-double is the default in 32-bit mode.
Modern architectures (Pentium and newer) prefer long double
to be aligned to an 8- or 16-byte boundary. In arrays or structures
conforming to the ABI, this is not possible. So specifying
-m128bit-long-double aligns long double
to a 16-byte boundary by padding the long double with an additional
32-bit zero.
In the x86-64 compiler, -m128bit-long-double is the default choice as
its ABI specifies that long double is to be aligned on 16-byte boundary.
Notice that neither of these options enable any extra precision over the x87
standard of 80 bits for a long double.
Warning: if you override the default value for your target ABI, the
structures and arrays containing long double variables will change
their size as well as function calling convention for function taking
long double will be modified. Hence they will not be binary
compatible with arrays or structures in code compiled without that switch.
-mlarge-data-threshold=number-mrtdret num
instruction, which pops their arguments while returning. This saves one
instruction in the caller since there is no need to pop the arguments
there.
You can specify that an individual function is called with this calling sequence with the function attribute ‘stdcall’. You can also override the -mrtd option by using the function attribute ‘cdecl’. See Function Attributes.
Warning: this calling convention is incompatible with the one normally used on Unix, so you cannot use it if you need to call libraries compiled with the Unix compiler.
Also, you must provide function prototypes for all functions that
take variable numbers of arguments (including printf);
otherwise incorrect code will be generated for calls to those
functions.
In addition, seriously incorrect code will result if you call a
function with too many arguments. (Normally, extra arguments are
harmlessly ignored.)
-mregparm=numWarning: if you use this switch, and
num is nonzero, then you must build all modules with the same
value, including any libraries. This includes the system libraries and
startup modules.
-msseregparmWarning: if you use this switch then you must build all
modules with the same value, including any libraries. This includes
the system libraries and startup modules.
-mvect8-ret-in-mem-mpc32-mpc64-mpc80Setting the rounding of floating-point operations to less than the default
80 bits can speed some programs by 2% or more. Note that some mathematical
libraries assume that extended-precision (80-bit) floating-point operations
are enabled by default; routines in such libraries could suffer significant
loss of accuracy, typically through so-called "catastrophic cancellation",
when this option is used to set the precision to less than extended precision.
-mstackrealignforce_align_arg_pointer,
applicable to individual functions.
-mpreferred-stack-boundary=num-mincoming-stack-boundary=numOn Pentium and PentiumPro, double and long double values
should be aligned to an 8-byte boundary (see -malign-double) or
suffer significant run time performance penalties. On Pentium III, the
Streaming SIMD Extension (SSE) data type __m128 may not work
properly if it is not 16-byte aligned.
To ensure proper alignment of this values on the stack, the stack boundary must be as aligned as that required by any value stored on the stack. Further, every function must be generated such that it keeps the stack aligned. Thus calling a function compiled with a higher preferred stack boundary from a function compiled with a lower preferred stack boundary will most likely misalign the stack. It is recommended that libraries that use callbacks always use the default setting.
This extra alignment does consume extra stack space, and generally
increases code size. Code that is sensitive to stack space usage, such
as embedded systems and operating system kernels, may want to reduce the
preferred alignment to -mpreferred-stack-boundary=2.
-mmmx-mno-mmx-msse-mno-sse-msse2-mno-sse2-msse3-mno-sse3-mssse3-mno-ssse3-msse4.1-mno-sse4.1-msse4.2-mno-sse4.2-msse4-mno-sse4-mavx-mno-avx-mavx2-mno-avx2-maes-mno-aes-mpclmul-mno-pclmul-mfsgsbase-mno-fsgsbase-mrdrnd-mno-rdrnd-mf16c-mno-f16c-mfma-mno-fma-msse4a-mno-sse4a-mfma4-mno-fma4-mxop-mno-xop-mlwp-mno-lwp-m3dnow-mno-3dnow-mpopcnt-mno-popcnt-mabm-mno-abm-mbmi-mbmi2-mno-bmi-mno-bmi2-mlzcnt-mno-lzcnt-mtbm-mno-tbmTo have SSE/SSE2 instructions generated automatically from floating-point code (as opposed to 387 instructions), see -mfpmath=sse.
GCC depresses SSEx instructions when -mavx is used. Instead, it generates new AVX instructions or AVX equivalence for all SSEx instructions when needed.
These options will enable GCC to use these extended instructions in
generated code, even without -mfpmath=sse. Applications that
perform run-time CPU detection must compile separate files for each
supported architecture, using the appropriate flags. In particular,
the file containing the CPU detection code should be compiled without
these options.
-mcldcld instruction in the prologue
of functions that use string instructions. String instructions depend on
the DF flag to select between autoincrement or autodecrement mode. While the
ABI specifies the DF flag to be cleared on function entry, some operating
systems violate this specification by not clearing the DF flag in their
exception dispatchers. The exception handler can be invoked with the DF flag
set, which leads to wrong direction mode when string instructions are used.
This option can be enabled by default on 32-bit x86 targets by configuring
GCC with the --enable-cld configure option. Generation of cld
instructions can be suppressed with the -mno-cld compiler option
in this case.
-mvzerouppervzeroupper instruction
before a transfer of control flow out of the function to minimize
AVX to SSE transition penalty as well as remove unnecessary zeroupper
intrinsics.
-mcx16-msahffmod, drem
or remainder built-in functions: see Other Builtins for details.
-mmovbe__builtin_bswap32 and __builtin_bswap64.
-mcrc32__builtin_ia32_crc32qi,
__builtin_ia32_crc32hi. __builtin_ia32_crc32si and
__builtin_ia32_crc32di to generate the crc32 machine instruction.
-mrecipNote that GCC implements 1.0f/sqrtf(x) in terms of RSQRTSS
(or RSQRTPS) already with -ffast-math (or the above option
combination), and doesn't need -mrecip.
Also note that GCC emits the above sequence with additional Newton-Raphson step
for vectorized single-float division and vectorized sqrtf(x)
already with -ffast-math (or the above option combination), and
doesn't need -mrecip.
-mrecip=opt! to invert the option:
all: enable all estimate instructions,
default: enable the default instructions, equivalent to -mrecip,
none: disable all estimate instructions, equivalent to -mno-recip,
div: enable the approximation for scalar division,
vec-div: enable the approximation for vectorized division,
sqrt: enable the approximation for scalar square root,
vec-sqrt: enable the approximation for vectorized square root.
So for example, -mrecip=all,!sqrt would enable
all of the reciprocal approximations, except for square root.
-mveclibabi=typesvml for the Intel short
vector math library and acml for the AMD math core library style
of interfacing. GCC will currently emit calls to vmldExp2,
vmldLn2, vmldLog102, vmldLog102, vmldPow2,
vmldTanh2, vmldTan2, vmldAtan2, vmldAtanh2,
vmldCbrt2, vmldSinh2, vmldSin2, vmldAsinh2,
vmldAsin2, vmldCosh2, vmldCos2, vmldAcosh2,
vmldAcos2, vmlsExp4, vmlsLn4, vmlsLog104,
vmlsLog104, vmlsPow4, vmlsTanh4, vmlsTan4,
vmlsAtan4, vmlsAtanh4, vmlsCbrt4, vmlsSinh4,
vmlsSin4, vmlsAsinh4, vmlsAsin4, vmlsCosh4,
vmlsCos4, vmlsAcosh4 and vmlsAcos4 for corresponding
function type when -mveclibabi=svml is used and __vrd2_sin,
__vrd2_cos, __vrd2_exp, __vrd2_log, __vrd2_log2,
__vrd2_log10, __vrs4_sinf, __vrs4_cosf,
__vrs4_expf, __vrs4_logf, __vrs4_log2f,
__vrs4_log10f and __vrs4_powf for corresponding function type
when -mveclibabi=acml is used. Both -ftree-vectorize and
-funsafe-math-optimizations have to be enabled. A SVML or ACML ABI
compatible library will have to be specified at link time.
-mabi=name-mtls-dialect=type-mpush-args-mno-push-args-maccumulate-outgoing-args-mthreads-mno-align-stringops-minline-all-stringops-minline-stringops-dynamically-mstringop-strategy=algrep_byte,
rep_4byte, rep_8byte for expanding using i386 rep prefix
of specified size, byte_loop, loop, unrolled_loop for
expanding inline loop, libcall for always expanding library call.
-momit-leaf-frame-pointer-mtls-direct-seg-refs-mno-tls-direct-seg-refs%gs for 32-bit, %fs for 64-bit),
or whether the thread base pointer must be added. Whether or not this
is legal depends on the operating system, and whether it maps the
segment to cover the entire TLS area.
For systems that use GNU libc, the default is on.
-msse2avx-mno-sse2avx-mfentry-mno-fentryms_hook_prologue
isn't possible at the moment for -mfentry and -pg.
-m8bit-idiv-mno-8bit-idiv-mavx256-split-unaligned-load-mavx256-split-unaligned-storeThese ‘-m’ switches are supported in addition to the above on AMD x86-64 processors in 64-bit environments.
-m32-m64-mx32-mno-red-zone-mcmodel=small-mcmodel=kernel-mcmodel=medium-mcmodel=largeThese additional options are available for Windows targets:
-mconsole-mdll-mnop-fun-dllimport-mthread-municode-mwin32-mwindows-fno-set-stack-executable-mpe-aligned-commonsSee also under i386 and x86-64 Options for standard options.
These are the ‘-m’ options defined for the Intel IA-64 architecture.
-mbig-endian-mlittle-endian-mgnu-as-mno-gnu-as-mgnu-ld-mno-gnu-ld-mno-pic-mvolatile-asm-stop-mno-volatile-asm-stop-mregister-names-mno-register-names-mno-sdata-msdata-mconstant-gp-mauto-pic-minline-float-divide-min-latency-minline-float-divide-max-throughput-mno-inline-float-divide-minline-int-divide-min-latency-minline-int-divide-max-throughput-mno-inline-int-divide-minline-sqrt-min-latency-minline-sqrt-max-throughput-mno-inline-sqrt-mfused-madd-mno-fused-madd-mno-dwarf2-asm-mdwarf2-asm-mearly-stop-bits-mno-early-stop-bits-mfixed-range=register-range-mtls-size=tls-size-mtune=cpu-type-milp32-mlp64-mno-sched-br-data-spec-msched-br-data-spec-msched-ar-data-spec-mno-sched-ar-data-spec-mno-sched-control-spec-msched-control-spec-msched-br-in-data-spec-mno-sched-br-in-data-spec-msched-ar-in-data-spec-mno-sched-ar-in-data-spec-msched-in-control-spec-mno-sched-in-control-spec-mno-sched-prefer-non-data-spec-insns-msched-prefer-non-data-spec-insns-mno-sched-prefer-non-control-spec-insns-msched-prefer-non-control-spec-insns-mno-sched-count-spec-in-critical-path-msched-count-spec-in-critical-path-msched-spec-ldc-msched-control-spec-ldc-msched-stop-bits-after-every-cycle-msched-fp-mem-deps-zero-cost-msel-sched-dont-check-control-spec-msched-max-memory-insns=max-insns-msched-max-memory-insns-hard-limitThese ‘-m’ options are defined for the IA-64/VMS implementations:
-mvms-return-codes-mdebug-main=prefix-mmalloc64These -m options are defined for the Lattice Mico32 architecture:
-mbarrel-shift-enabled-mdivide-enabled-mmultiply-enabled-msign-extend-enabled-muser-enabled-mcpu=name-msim-memregs=numberThese -m options are defined for Renesas M32R/D architectures:
-m32r2-m32rx-m32r-mmodel=smallld24 instruction), and assume all subroutines
are reachable with the bl instruction.
This is the default.
The addressability of a particular object can be set with the
model attribute.
-mmodel=mediumseth/add3 instructions to load their addresses), and
assume all subroutines are reachable with the bl instruction.
-mmodel=largeseth/add3 instructions to load their addresses), and
assume subroutines may not be reachable with the bl instruction
(the compiler will generate the much slower seth/add3/jl
instruction sequence).
-msdata=nonesection attribute has been specified).
This is the default.
The small data area consists of sections ‘.sdata’ and ‘.sbss’.
Objects may be explicitly put in the small data area with the
section attribute using one of these sections.
-msdata=sdata-msdata=use-G numAll modules should be compiled with the same -G num value.
Compiling with different values of num may or may not work; if it
doesn't the linker will give an error message—incorrect code will not be
generated.
-mdebug-malign-loops-mno-align-loops-missue-rate=number-mbranch-cost=number-mflush-trap=number-mno-flush-trap-mflush-func=name-mno-flush-funcThese are the ‘-m’ options defined for M680x0 and ColdFire processors. The default settings depend on which architecture was selected when the compiler was configured; the defaults for the most common choices are given below.
-march=archgcc defines a macro ‘__mcfarch__’ whenever it is generating code for a ColdFire target. The arch in this macro is one of the -march arguments given above.
When used together, -march and -mtune select code
that runs on a family of similar processors but that is optimized
for a particular microarchitecture.
-mcpu=cpu| Family | ‘-mcpu’ arguments
|
| ‘51’ | ‘51’ ‘51ac’ ‘51cn’ ‘51em’ ‘51qe’
|
| ‘5206’ | ‘5202’ ‘5204’ ‘5206’
|
| ‘5206e’ | ‘5206e’
|
| ‘5208’ | ‘5207’ ‘5208’
|
| ‘5211a’ | ‘5210a’ ‘5211a’
|
| ‘5213’ | ‘5211’ ‘5212’ ‘5213’
|
| ‘5216’ | ‘5214’ ‘5216’
|
| ‘52235’ | ‘52230’ ‘52231’ ‘52232’ ‘52233’ ‘52234’ ‘52235’
|
| ‘5225’ | ‘5224’ ‘5225’
|
| ‘52259’ | ‘52252’ ‘52254’ ‘52255’ ‘52256’ ‘52258’ ‘52259’
|
| ‘5235’ | ‘5232’ ‘5233’ ‘5234’ ‘5235’ ‘523x’
|
| ‘5249’ | ‘5249’
|
| ‘5250’ | ‘5250’
|
| ‘5271’ | ‘5270’ ‘5271’
|
| ‘5272’ | ‘5272’
|
| ‘5275’ | ‘5274’ ‘5275’
|
| ‘5282’ | ‘5280’ ‘5281’ ‘5282’ ‘528x’
|
| ‘53017’ | ‘53011’ ‘53012’ ‘53013’ ‘53014’ ‘53015’ ‘53016’ ‘53017’
|
| ‘5307’ | ‘5307’
|
| ‘5329’ | ‘5327’ ‘5328’ ‘5329’ ‘532x’
|
| ‘5373’ | ‘5372’ ‘5373’ ‘537x’
|
| ‘5407’ | ‘5407’
|
| ‘5475’ | ‘5470’ ‘5471’ ‘5472’ ‘5473’ ‘5474’ ‘5475’ ‘547x’ ‘5480’ ‘5481’ ‘5482’ ‘5483’ ‘5484’ ‘5485’
|
-mcpu=cpu overrides -march=arch if arch is compatible with cpu. Other combinations of -mcpu and -march are rejected.
gcc defines the macro ‘__mcf_cpu_cpu’ when ColdFire target
cpu is selected. It also defines ‘__mcf_family_family’,
where the value of family is given by the table above.
-mtune=tuneYou can also use -mtune=68020-40 for code that needs to run relatively well on 68020, 68030 and 68040 targets. -mtune=68020-60 is similar but includes 68060 targets as well. These two options select the same tuning decisions as -m68020-40 and -m68020-60 respectively.
gcc defines the macros ‘__mcarch’ and ‘__mcarch__’ when tuning for 680x0 architecture arch. It also defines ‘mcarch’ unless either -ansi or a non-GNU -std option is used. If gcc is tuning for a range of architectures, as selected by -mtune=68020-40 or -mtune=68020-60, it defines the macros for every architecture in the range.
gcc also defines the macro ‘__muarch__’ when tuning for
ColdFire microarchitecture uarch, where uarch is one
of the arguments given above.
-m68000-mc68000Use this option for microcontrollers with a 68000 or EC000 core,
including the 68008, 68302, 68306, 68307, 68322, 68328 and 68356.
-m68010-m68020-mc68020-m68030-m68040This option inhibits the use of 68881/68882 instructions that have to be
emulated by software on the 68040. Use this option if your 68040 does not
have code to emulate those instructions.
-m68060This option inhibits the use of 68020 and 68881/68882 instructions that
have to be emulated by software on the 68060. Use this option if your 68060
does not have code to emulate those instructions.
-mcpu32Use this option for microcontrollers with a
CPU32 or CPU32+ core, including the 68330, 68331, 68332, 68333, 68334,
68336, 68340, 68341, 68349 and 68360.
-m5200Use this option for microcontroller with a 5200 core, including
the MCF5202, MCF5203, MCF5204 and MCF5206.
-m5206e-m528x-m5307-m5407-mcfv4e-m68020-40The option is equivalent to -march=68020 -mtune=68020-40.
-m68020-60The option is equivalent to -march=68020 -mtune=68020-60.
-mhard-float-m68881-msoft-float-mdiv-mno-divgcc defines the macro ‘__mcfhwdiv__’ when this option is enabled.
-mshortint to be 16 bits wide, like short int.
Additionally, parameters passed on the stack are also aligned to a
16-bit boundary even on targets whose API mandates promotion to 32-bit.
-mno-shortint to be 16 bits wide. This is the default.
-mnobitfield-mno-bitfield-mbitfield-mrtdrtd
instruction, which pops their arguments while returning. This
saves one instruction in the caller since there is no need to pop
the arguments there.
This calling convention is incompatible with the one normally used on Unix, so you cannot use it if you need to call libraries compiled with the Unix compiler.
Also, you must provide function prototypes for all functions that
take variable numbers of arguments (including printf);
otherwise incorrect code will be generated for calls to those
functions.
In addition, seriously incorrect code will result if you call a function with too many arguments. (Normally, extra arguments are harmlessly ignored.)
The rtd instruction is supported by the 68010, 68020, 68030,
68040, 68060 and CPU32 processors, but not by the 68000 or 5200.
-mno-rtd-malign-int-mno-align-intint, long, long long,
float, double, and long double variables on a 32-bit
boundary (-malign-int) or a 16-bit boundary (-mno-align-int).
Aligning variables on 32-bit boundaries produces code that runs somewhat
faster on processors with 32-bit busses at the expense of more memory.
Warning: if you use the -malign-int switch, GCC will
align structures containing the above types differently than
most published application binary interface specifications for the m68k.
-mpcrel-mno-strict-align-mstrict-align-msep-data-mno-sep-data-mid-shared-library-mno-id-shared-library-mshared-library-id=n-mxgot-mno-xgotGCC normally uses a single instruction to load values from the GOT. While this is relatively efficient, it only works if the GOT is smaller than about 64k. Anything larger causes the linker to report an error such as:
relocation truncated to fit: R_68K_GOT16O foobar
If this happens, you should recompile your code with -mxgot. It should then work with very large GOTs. However, code generated with -mxgot is less efficient, since it takes 4 instructions to fetch the value of a global symbol.
Note that some linkers, including newer versions of the GNU linker, can create multiple GOTs and sort GOT entries. If you have such a linker, you should only need to use -mxgot when compiling a single object file that accesses more than 8192 GOT entries. Very few do.
These options have no effect unless GCC is generating position-independent code.
These are the ‘-m’ options defined for the Motorola M*Core processors.
-mhardlit-mno-hardlit-mdiv-mno-div-mrelax-immediate-mno-relax-immediate-mwide-bitfields-mno-wide-bitfields-m4byte-functions-mno-4byte-functions-mcallgraph-data-mno-callgraph-data-mslow-bytes-mno-slow-bytes-mlittle-endian-mbig-endian-m210-m340-mno-lsim-mstack-increment=size-mabsdiffabs instruction, which is the absolute difference
between two registers.
-mall-opts-maverageave instruction, which computes the average of two
registers.
-mbased=n.based section by default. Based variables use the $tp
register as a base register, and there is a 128-byte limit to the
.based section.
-mbitopsbtstm), set
(bsetm), clear (bclrm), invert (bnotm), and
test-and-set (tas).
-mc=nametiny, near, or far.
-mclipclip instruction. Note that -mclip is not
useful unless you also provide -mminmax.
-mconfig=nameMeP-Integrator tool, not part of GCC, provides these
configurations through this option; using this option is the same as
using all the corresponding command-line options. The default
configuration is default.
-mcop-mconfig= option.
-mcop32-mcop64-mivc2-mdc.near section.
-mdivdiv and divu instructions.
-meb-mel-mio-volatileio
attribute is to be considered volatile.
-ml.far section by default.
-mleadzleadz (leading zero) instruction.
-mm.near section by default.
-mminmaxmin and max instructions.
-mmult-mno-opts-mall-opts.
-mrepeatrepeat and erepeat instructions, used for
low-overhead looping.
-ms.tiny section. Note
that there is a 65536-byte limit to this section. Accesses to these
variables use the %gp base register.
-msaturas.
-msdram-msim-msimnovec-mtf.far section. Without
this option, functions default to the .near section.
-mtiny=n.tiny section. These variables use the $gp base
register. The default for this option is 4, but note that there's a
65536-byte limit to the .tiny section.
-msoft-float-mhard-float-mmemcpymemcpy.
-mno-clearbss-mcpu=cpu-type-mxl-soft-mul-mxl-soft-div-mxl-barrel-shift-mxl-pattern-compare-msmall-divides-mxl-stack-check-mxl-gp-opt-mxl-multiply-high-mxl-float-convert-mxl-float-sqrt-mxl-mode-app-modelOption -xl-mode-app-model is a deprecated alias for -mxl-mode-app-model.
-EB-EL-march=archNative Linux/GNU and IRIX toolchains also support the value ‘native’, which selects the best architecture option for the host processor. -march=native has no effect if GCC does not recognize the processor.
In processor names, a final ‘000’ can be abbreviated as ‘k’ (for example, ‘-march=r2k’). Prefixes are optional, and ‘vr’ may be written ‘r’.
Names of the form ‘nf2_1’ refer to processors with FPUs clocked at half the rate of the core, names of the form ‘nf1_1’ refer to processors with FPUs clocked at the same rate as the core, and names of the form ‘nf3_2’ refer to processors with FPUs clocked a ratio of 3:2 with respect to the core. For compatibility reasons, ‘nf’ is accepted as a synonym for ‘nf2_1’ while ‘nx’ and ‘bfx’ are accepted as synonyms for ‘nf1_1’.
GCC defines two macros based on the value of this option. The first is ‘_MIPS_ARCH’, which gives the name of target architecture, as a string. The second has the form ‘_MIPS_ARCH_foo’, where foo is the capitalized value of ‘_MIPS_ARCH’. For example, ‘-march=r2000’ will set ‘_MIPS_ARCH’ to ‘"r2000"’ and define the macro ‘_MIPS_ARCH_R2000’.
Note that the ‘_MIPS_ARCH’ macro uses the processor names given
above. In other words, it will have the full prefix and will not
abbreviate ‘000’ as ‘k’. In the case of ‘from-abi’,
the macro names the resolved architecture (either ‘"mips1"’ or
‘"mips3"’). It names the default architecture when no
-march option is given.
-mtune=archWhen this option is not used, GCC will optimize for the processor specified by -march. By using -march and -mtune together, it is possible to generate code that will run on a family of processors, but optimize the code for one particular member of that family.
‘-mtune’ defines the macros ‘_MIPS_TUNE’ and
‘_MIPS_TUNE_foo’, which work in the same way as the
‘-march’ ones described above.
-mips1-mips2-mips3-mips4-mips32-mips32r2-mips64-mips64r2-mips16-mno-mips16MIPS16 code generation can also be controlled on a per-function basis
by means of mips16 and nomips16 attributes.
See Function Attributes, for more information.
-mflip-mips16-minterlink-mips16-mno-interlink-mips16For example, non-MIPS16 code cannot jump directly to MIPS16 code;
it must either use a call or an indirect jump. -minterlink-mips16
therefore disables direct jumps unless GCC knows that the target of the
jump is not MIPS16.
-mabi=32-mabi=o64-mabi=n32-mabi=64-mabi=eabiNote that the EABI has a 32-bit and a 64-bit variant. GCC normally generates 64-bit code when you select a 64-bit architecture, but you can use -mgp32 to get 32-bit code instead.
For information about the O64 ABI, see http://gcc.gnu.org/projects/mipso64-abi.html.
GCC supports a variant of the o32 ABI in which floating-point registers are 64 rather than 32 bits wide. You can select this combination with -mabi=32 -mfp64. This ABI relies on the ‘mthc1’ and ‘mfhc1’ instructions and is therefore only supported for MIPS32R2 processors.
The register assignments for arguments and return values remain the
same, but each scalar value is passed in a single 64-bit register
rather than a pair of 32-bit registers. For example, scalar
floating-point values are returned in ‘$f0’ only, not a
‘$f0’/‘$f1’ pair. The set of call-saved registers also
remains the same, but all 64 bits are saved.
-mabicalls-mno-abicalls-mshared-mno-sharedAll -mabicalls code has traditionally been position-independent, regardless of options like -fPIC and -fpic. However, as an extension, the GNU toolchain allows executables to use absolute accesses for locally-binding symbols. It can also use shorter GP initialization sequences and generate direct calls to locally-defined functions. This mode is selected by -mno-shared.
-mno-shared depends on binutils 2.16 or higher and generates objects that can only be linked by the GNU linker. However, the option does not affect the ABI of the final executable; it only affects the ABI of relocatable objects. Using -mno-shared will generally make executables both smaller and quicker.
-mshared is the default.
-mplt-mno-pltYou can make -mplt the default by configuring
GCC with --with-mips-plt. The default is
-mno-plt otherwise.
-mxgot-mno-xgotGCC normally uses a single instruction to load values from the GOT. While this is relatively efficient, it will only work if the GOT is smaller than about 64k. Anything larger will cause the linker to report an error such as:
relocation truncated to fit: R_MIPS_GOT16 foobar
If this happens, you should recompile your code with -mxgot. It should then work with very large GOTs, although it will also be less efficient, since it will take three instructions to fetch the value of a global symbol.
Note that some linkers can create multiple GOTs. If you have such a linker, you should only need to use -mxgot when a single object file accesses more than 64k's worth of GOT entries. Very few do.
These options have no effect unless GCC is generating position
independent code.
-mgp32-mgp64-mfp32-mfp64-mhard-float-msoft-float-msingle-float-mdouble-float-mllsc-mno-llsc-mllsc is useful if the runtime environment can emulate the
instructions and -mno-llsc can be useful when compiling for
nonstandard ISAs. You can make either option the default by
configuring GCC with --with-llsc and --without-llsc
respectively. --with-llsc is the default for some
configurations; see the installation documentation for details.
-mdsp-mno-dsp-mdspr2-mno-dspr2-msmartmips-mno-smartmips-mpaired-single-mno-paired-single-mdmx-mno-mdmx-mips3d-mno-mips3d-mmt-mno-mt-mlong64long types to be 64 bits wide. See -mlong32 for
an explanation of the default and the way that the pointer size is
determined.
-mlong32long, int, and pointer types to be 32 bits wide.
The default size of ints, longs and pointers depends on
the ABI. All the supported ABIs use 32-bit ints. The n64 ABI
uses 64-bit longs, as does the 64-bit EABI; the others use
32-bit longs. Pointers are the same size as longs,
or the same size as integer registers, whichever is smaller.
-msym32-mno-sym32-G numThe default -G option depends on the configuration.
-mlocal-sdata-mno-local-sdataIf the linker complains that an application is using too much small data,
you might want to try rebuilding the less performance-critical parts with
-mno-local-sdata. You might also want to build large
libraries with -mno-local-sdata, so that the libraries leave
more room for the main program.
-mextern-sdata-mno-extern-sdataIf you compile a module Mod with -mextern-sdata -G
num -mgpopt, and Mod references a variable Var
that is no bigger than num bytes, you must make sure that Var
is placed in a small data section. If Var is defined by another
module, you must either compile that module with a high-enough
-G setting or attach a section attribute to Var's
definition. If Var is common, you must link the application
with a high-enough -G setting.
The easiest way of satisfying these restrictions is to compile
and link every module with the same -G option. However,
you may wish to build a library that supports several different
small data limits. You can do this by compiling the library with
the highest supported -G setting and additionally using
-mno-extern-sdata to stop the library from making assumptions
about externally-defined data.
-mgpopt-mno-gpopt-mno-gpopt is useful for cases where the $gp register
might not hold the value of _gp. For example, if the code is
part of a library that might be used in a boot monitor, programs that
call boot monitor routines will pass an unknown value in $gp.
(In such situations, the boot monitor itself would usually be compiled
with -G0.)
-mno-gpopt implies -mno-local-sdata and
-mno-extern-sdata.
-membedded-data-mno-embedded-data-muninit-const-in-rodata-mno-uninit-const-in-rodataconst variables in the read-only data section.
This option is only meaningful in conjunction with -membedded-data.
-mcode-readable=setting-mcode-readable=yes-mcode-readable=pcrel-mcode-readable=no-msplit-addresses-mno-split-addresses%hi() and %lo() assembler
relocation operators. This option has been superseded by
-mexplicit-relocs but is retained for backwards compatibility.
-mexplicit-relocs-mno-explicit-relocs-mexplicit-relocs is the default if GCC was configured
to use an assembler that supports relocation operators.
-mcheck-zero-division-mno-check-zero-divisionThe default is -mcheck-zero-division.
-mdivide-traps-mdivide-breaksSIGFPE). Use -mdivide-traps to
allow conditional traps on architectures that support them and
-mdivide-breaks to force the use of breaks.
The default is usually -mdivide-traps, but this can be
overridden at configure time using --with-divide=breaks.
Divide-by-zero checks can be completely disabled using
-mno-check-zero-division.
-mmemcpy-mno-memcpymemcpy() for non-trivial block
moves. The default is -mno-memcpy, which allows GCC to inline
most constant-sized copies.
-mlong-calls-mno-long-callsjal instruction. Calling
functions using jal is more efficient but requires the caller
and callee to be in the same 256 megabyte segment.
This option has no effect on abicalls code. The default is
-mno-long-calls.
-mmad-mno-madmad, madu and mul
instructions, as provided by the R4650 ISA.
-mfused-madd-mno-fused-maddWhen multiply-accumulate instructions are used, the intermediate
product is calculated to infinite precision and is not subject to
the FCSR Flush to Zero bit. This may be undesirable in some
circumstances.
-nocpp-mfix-24k-mno-fix-24k-mfix-r4000-mno-fix-r4000-mfix-r4400-mno-fix-r4400-mfix-r10000-mno-fix-r10000ll/sc sequences may not behave atomically on revisions
prior to 3.0. They may deadlock on revisions 2.6 and earlier.
This option can only be used if the target architecture supports
branch-likely instructions. -mfix-r10000 is the default when
-march=r10000 is used; -mno-fix-r10000 is the default
otherwise.
-mfix-vr4120-mno-fix-vr4120dmultu does not always produce the correct result.
div and ddiv do not always produce the correct result if one
of the operands is negative.
mips64vr*-elf configurations.
Other VR4120 errata require a nop to be inserted between certain pairs of
instructions. These errata are handled by the assembler, not by GCC itself.
-mfix-vr4130mflo/mfhi errata. The
workarounds are implemented by the assembler rather than by GCC,
although GCC will avoid using mflo and mfhi if the
VR4130 macc, macchi, dmacc and dmacchi
instructions are available instead.
-mfix-sb1-mno-fix-sb1-mr10k-cache-barrier=settingIn common with many processors, the R10K tries to predict the outcome of a conditional branch and speculatively executes instructions from the “taken” branch. It later aborts these instructions if the predicted outcome was wrong. However, on the R10K, even aborted instructions can have side effects.
This problem only affects kernel stores and, depending on the system, kernel loads. As an example, a speculatively-executed store may load the target memory into cache and mark the cache line as dirty, even if the store itself is later aborted. If a DMA operation writes to the same area of memory before the “dirty” line is flushed, the cached data will overwrite the DMA-ed data. See the R10K processor manual for a full description, including other potential problems.
One workaround is to insert cache barrier instructions before every memory access that might be speculatively executed and that might have side effects even if aborted. -mr10k-cache-barrier=setting controls GCC's implementation of this workaround. It assumes that aborted accesses to any byte in the following regions will not have side effects:
It is the kernel's responsibility to ensure that speculative accesses to these regions are indeed safe.
If the input program contains a function declaration such as:
void foo (void);
then the implementation of foo must allow j foo and
jal foo to be executed speculatively. GCC honors this
restriction for functions it compiles itself. It expects non-GCC
functions (such as hand-written assembly code) to do the same.
The option has three forms:
-mr10k-cache-barrier=load-store-mr10k-cache-barrier=store-mr10k-cache-barrier=none-mflush-func=func-mno-flush-func_flush_func(), that is, the address of the
memory range for which the cache is being flushed, the size of the
memory range, and the number 3 (to flush both caches). The default
depends on the target GCC was configured for, but commonly is either
‘_flush_func’ or ‘__cpu_flush’.
mbranch-cost=num-mbranch-likely-mno-branch-likely-mfp-exceptions-mno-fp-exceptionsFor instance, on the SB-1, if FP exceptions are disabled, and we are emitting
64-bit code, then we can use both FP pipes. Otherwise, we can only use one
FP pipe.
-mvr4130-align-mno-vr4130-alignThis option only has an effect when optimizing for the VR4130.
It normally makes code faster, but at the expense of making it bigger.
It is enabled by default at optimization level -O3.
-msynci-mno-syncisynci instructions on
architectures that support it. The synci instructions (if
enabled) will be generated when __builtin___clear_cache() is
compiled.
This option defaults to -mno-synci, but the default can be
overridden by configuring with --with-synci.
When compiling code for single processor systems, it is generally safe
to use synci. However, on many multi-core (SMP) systems, it
will not invalidate the instruction caches on all cores and may lead
to undefined behavior.
-mrelax-pic-calls-mno-relax-pic-calls$25 into direct calls. This is only possible if the linker can
resolve the destination at link-time and if the destination is within
range for a direct call.
-mrelax-pic-calls is the default if GCC was configured to use
an assembler and a linker that supports the .reloc assembly
directive and -mexplicit-relocs is in effect. With
-mno-explicit-relocs, this optimization can be performed by the
assembler and the linker alone without help from the compiler.
-mmcount-ra-address-mno-mcount-ra-address_mcount to modify the
calling function's return address. When enabled, this option extends
the usual _mcount interface with a new ra-address
parameter, which has type intptr_t * and is passed in register
$12. _mcount can then modify the return address by
doing both of the following:
$31.
*ra-address,
if ra-address is nonnull.
The default is -mno-mcount-ra-address.
These options are defined for the MMIX:
-mlibfuncs-mno-libfuncs-mepsilon-mno-epsilonrE epsilon register.
-mabi=mmixware-mabi=gnu$0 and up, as opposed to
the GNU ABI which uses global registers $231 and up.
-mzero-extend-mno-zero-extend-mknuthdiv-mno-knuthdiv-mtoplevel-symbols-mno-toplevel-symbolsPREFIX assembly directive.
-melf-mbranch-predict-mno-branch-predict-mbase-addresses-mno-base-addresses-msingle-exit-mno-single-exitThese -m options are defined for Matsushita MN10300 architectures:
-mmult-bug-mno-mult-bug-mam33-mno-am33-mam33-2-mam34-mtune=cpu-type-mreturn-pointer-on-d0a0 and d0. Otherwise, the pointer is returned
only in a0, and attempts to call such functions without a prototype
would result in errors. Note that this option is on by default; use
-mno-return-pointer-on-d0 to disable it.
-mno-crt0-mrelaxThis option makes symbolic debugging impossible.
-mliw-mnoliw-msetlb-mnosetlbThese options are defined for the PDP-11:
-mfpu-msoft-float-mac0-mno-ac0-m40-m45-m10-mbcopy-builtinmovmemhi patterns for copying memory. This is the
default.
-mbcopymovmemhi patterns for copying memory.
-mint16-mno-int32int. This is the default.
-mint32-mno-int16int.
-mfloat64-mno-float32float. This is the default.
-mfloat32-mno-float64float.
-mabshiabshi2 pattern. This is the default.
-mno-abshiabshi2 pattern.
-mbranch-expensive-mbranch-cheap-munix-asm-mdec-asmThese ‘-m’ options are defined for picoChip implementations:
-mae=ae_type-mae=ANY selects a completely generic AE type. Code generated with this option will run on any of the other AE types. The code will not be as efficient as it would be if compiled for a specific AE type, and some types of operation (e.g., multiplication) will not work properly on all types of AE.
-mae=MUL selects a MUL AE type. This is the most useful AE type for compiled code, and is the default.
-mae=MAC selects a DSP-style MAC AE. Code compiled with this
option may suffer from poor performance of byte (char) manipulation,
since the DSP AE does not provide hardware support for byte load/stores.
-msymbol-as-address-mno-inefficient-warningsThese are listed under See RS/6000 and PowerPC Options.
-msim-mmul=none-mmul=g13-mmul=rl78none, which uses software multiplication functions.
The g13 option is for the hardware multiply/divide peripheral
only on the RL78/G13 targets. The rl78 option is for the
standard hardware multiplication defined in the RL78 software manual.
These ‘-m’ options are defined for the IBM RS/6000 and PowerPC:
-mpower-mno-power-mpower2-mno-power2-mpowerpc-mno-powerpc-mpowerpc-gpopt-mno-powerpc-gpopt-mpowerpc-gfxopt-mno-powerpc-gfxopt-mpowerpc64-mno-powerpc64-mmfcrf-mno-mfcrf-mpopcntb-mno-popcntb-mpopcntd-mno-popcntd-mfprnd-mno-fprnd-mcmpb-mno-cmpb-mmfpgpr-mno-mfpgpr-mhard-dfp-mno-hard-dfpNeither architecture is a subset of the other. However there is a large common subset of instructions supported by both. An MQ register is included in processors supporting the POWER architecture.
You use these options to specify which instructions are available on the processor you are using. The default value of these options is determined when configuring GCC. Specifying the -mcpu=cpu_type overrides the specification of these options. We recommend you use the -mcpu=cpu_type option rather than the options listed above.
The -mpower option allows GCC to generate instructions that are found only in the POWER architecture and to use the MQ register. Specifying -mpower2 implies -power and also allows GCC to generate instructions that are present in the POWER2 architecture but not the original POWER architecture.
The -mpowerpc option allows GCC to generate instructions that are found only in the 32-bit subset of the PowerPC architecture. Specifying -mpowerpc-gpopt implies -mpowerpc and also allows GCC to use the optional PowerPC architecture instructions in the General Purpose group, including floating-point square root. Specifying -mpowerpc-gfxopt implies -mpowerpc and also allows GCC to use the optional PowerPC architecture instructions in the Graphics group, including floating-point select.
The -mmfcrf option allows GCC to generate the move from condition register field instruction implemented on the POWER4 processor and other processors that support the PowerPC V2.01 architecture. The -mpopcntb option allows GCC to generate the popcount and double-precision FP reciprocal estimate instruction implemented on the POWER5 processor and other processors that support the PowerPC V2.02 architecture. The -mpopcntd option allows GCC to generate the popcount instruction implemented on the POWER7 processor and other processors that support the PowerPC V2.06 architecture. The -mfprnd option allows GCC to generate the FP round to integer instructions implemented on the POWER5+ processor and other processors that support the PowerPC V2.03 architecture. The -mcmpb option allows GCC to generate the compare bytes instruction implemented on the POWER6 processor and other processors that support the PowerPC V2.05 architecture. The -mmfpgpr option allows GCC to generate the FP move to/from general-purpose register instructions implemented on the POWER6X processor and other processors that support the extended PowerPC V2.05 architecture. The -mhard-dfp option allows GCC to generate the decimal floating-point instructions implemented on some POWER processors.
The -mpowerpc64 option allows GCC to generate the additional 64-bit instructions that are found in the full PowerPC64 architecture and to treat GPRs as 64-bit, doubleword quantities. GCC defaults to -mno-powerpc64.
If you specify both -mno-power and -mno-powerpc, GCC
will use only the instructions in the common subset of both
architectures plus some special AIX common-mode calls, and will not use
the MQ register. Specifying both -mpower and -mpowerpc
permits GCC to use any instruction from either architecture and to
allow use of the MQ register; specify this for the Motorola MPC601.
-mnew-mnemonics-mold-mnemonicsGCC defaults to the mnemonics appropriate for the architecture in
use. Specifying -mcpu=cpu_type sometimes overrides the
value of these option. Unless you are building a cross-compiler, you
should normally not specify either -mnew-mnemonics or
-mold-mnemonics, but should instead accept the default.
-mcpu=cpu_type-mcpu=common selects a completely generic processor. Code generated under this option will run on any POWER or PowerPC processor. GCC will use only the instructions in the common subset of both architectures, and will not use the MQ register. GCC assumes a generic processor model for scheduling purposes.
-mcpu=power, -mcpu=power2, -mcpu=powerpc, and -mcpu=powerpc64 specify generic POWER, POWER2, pure 32-bit PowerPC (i.e., not MPC601), and 64-bit PowerPC architecture machine types, with an appropriate, generic processor model assumed for scheduling purposes.
The other options specify a specific processor. Code generated under those options will run best on that processor, and may not run at all on others.
The -mcpu options automatically enable or disable the following options:
-maltivec -mfprnd -mhard-float -mmfcrf -mmultiple
-mnew-mnemonics -mpopcntb -mpopcntd -mpower -mpower2 -mpowerpc64
-mpowerpc-gpopt -mpowerpc-gfxopt -msingle-float -mdouble-float
-msimple-fpu -mstring -mmulhw -mdlmzb -mmfpgpr -mvsx
The particular options set for any particular CPU will vary between compiler versions, depending on what setting seems to produce optimal code for that CPU; it doesn't necessarily reflect the actual hardware's capabilities. If you wish to set an individual option to a particular value, you may specify it after the -mcpu option, like ‘-mcpu=970 -mno-altivec’.
On AIX, the -maltivec and -mpowerpc64 options are
not enabled or disabled by the -mcpu option at present because
AIX does not have full support for these options. You may still
enable or disable them individually if you're sure it'll work in your
environment.
-mtune=cpu_type-mcmodel=small-mcmodel=medium-mcmodel=large-maltivec-mno-altivec-mvrsave-mno-vrsave-mgen-cell-microcode-mwarn-cell-microcode-msecure-plt-mbss-plt-misel-mno-isel-misel=yes/no-mspe-mno-spe-mpaired-mno-paired-mspe=yes/no-mvsx-mno-vsx-mfloat-gprs=yes/single/double/no-mfloat-gprsThe argument yes or single enables the use of single-precision floating-point operations.
The argument double enables the use of single and double-precision floating-point operations.
The argument no disables floating-point operations on the general-purpose registers.
This option is currently only available on the MPC854x.
-m32-m64-mfull-toc-mno-fp-in-toc-mno-sum-in-toc-mminimal-tocIf you receive a linker error message that saying you have overflowed the available TOC space, you can reduce the amount of TOC space used with the -mno-fp-in-toc and -mno-sum-in-toc options. -mno-fp-in-toc prevents GCC from putting floating-point constants in the TOC and -mno-sum-in-toc forces GCC to generate code to calculate the sum of an address and a constant at run time instead of putting that sum into the TOC. You may specify one or both of these options. Each causes GCC to produce very slightly slower and larger code at the expense of conserving TOC space.
If you still run out of space in the TOC even when you specify both of
these options, specify -mminimal-toc instead. This option causes
GCC to make only one TOC entry for every file. When you specify this
option, GCC will produce code that is slower and larger but which
uses extremely little TOC space. You may wish to use this option
only on files that contain less frequently executed code.
-maix64-maix32long type, and the infrastructure needed to support them.
Specifying -maix64 implies -mpowerpc64 and
-mpowerpc, while -maix32 disables the 64-bit ABI and
implies -mno-powerpc64. GCC defaults to -maix32.
-mxl-compat-mno-xl-compatThe AIX calling convention was extended but not initially documented to
handle an obscure K&R C case of calling a function that takes the
address of its arguments with fewer arguments than declared. IBM XL
compilers access floating-point arguments that do not fit in the
RSA from the stack when a subroutine is compiled without
optimization. Because always storing floating-point arguments on the
stack is inefficient and rarely needed, this option is not enabled by
default and only is necessary when calling subroutines compiled by IBM
XL compilers without optimization.
-mpe-malign-natural-malign-powerOn 64-bit Darwin, natural alignment is the default, and -malign-power
is not supported.
-msoft-float-mhard-float-msingle-float-mdouble-float-msimple-fpu-mfpu-mxilinx-fpu-mmultiple-mno-multiple-mstring-mno-string-mupdate-mno-update-mavoid-indexed-addresses-mno-avoid-indexed-addresses-mfused-madd-mno-fused-madd-mmulhw-mno-mulhw-mdlmzb-mno-dlmzb-mno-bit-align-mbit-alignFor example, by default a structure containing nothing but 8
unsigned bit-fields of length 1 is aligned to a 4-byte
boundary and has a size of 4 bytes. By using -mno-bit-align,
the structure is aligned to a 1-byte boundary and is 1 byte in
size.
-mno-strict-align-mstrict-align-mrelocatable-mno-relocatable.got2 and 4-byte locations listed in the .fixup section,
a table of 32-bit addresses generated by this option. For this to
work, all objects linked together must be compiled with
-mrelocatable or -mrelocatable-lib.
-mrelocatable code aligns the stack to an 8-byte boundary.
-mrelocatable-lib-mno-relocatable-lib.fixup section to allow static executables to be relocated at
run time, but -mrelocatable-lib does not use the smaller stack
alignment of -mrelocatable. Objects compiled with
-mrelocatable-lib may be linked with objects compiled with
any combination of the -mrelocatable options.
-mno-toc-mtoc-mlittle-mlittle-endian-mbig-mbig-endian-mdynamic-no-pic-msingle-pic-base-mprioritize-restricted-insns=priority-msched-costly-dep=dependence_type-minsert-sched-nops=scheme-mcall-sysv-mcall-sysv-eabi-mcall-eabi-mcall-sysv-noeabi-mcall-aixdesc-mcall-linux-mcall-freebsd-mcall-netbsd-mcall-openbsd-maix-struct-return-msvr4-struct-return-mabi=abi-type-mabi=spe-mabi=no-spe-mabi=ibmlongdouble-mabi=ieeelongdouble-mprototype-mno-prototype-msim-mmvme-mads-myellowknife-mvxworks-memb-meabi-mno-eabi__eabi is called to from main to set up the eabi
environment, and the -msdata option can use both r2 and
r13 to point to two separate small data areas. Selecting
-mno-eabi means that the stack is aligned to a 16-byte boundary,
do not call an initialization function from main, and the
-msdata option will only use r13 to point to a single
small data area. The -meabi option is on by default if you
configured GCC using one of the ‘powerpc*-*-eabi*’ options.
-msdata=eabiconst global and static data in the ‘.sdata2’ section, which
is pointed to by register r2. Put small initialized
non-const global and static data in the ‘.sdata’ section,
which is pointed to by register r13. Put small uninitialized
global and static data in the ‘.sbss’ section, which is adjacent to
the ‘.sdata’ section. The -msdata=eabi option is
incompatible with the -mrelocatable option. The
-msdata=eabi option also sets the -memb option.
-msdata=sysvr13. Put small uninitialized global and static data in the
‘.sbss’ section, which is adjacent to the ‘.sdata’ section.
The -msdata=sysv option is incompatible with the
-mrelocatable option.
-msdata=default-msdata-msdata=datar13
to address small data however. This is the default behavior unless
other -msdata options are used.
-msdata=none-mno-sdata-mblock-move-inline-limit=nummemcpy or structure
copies) less than or equal to num bytes. The minimum value for
num is 32 bytes on 32-bit targets and 64 bytes on 64-bit
targets. The default value is target-specific.
-G num-mregnames-mno-regnames-mlongcall-mno-longcallshortcall function attribute, or by #pragma
longcall(0).
Some linkers are capable of detecting out-of-range calls and generating glue code on the fly. On these systems, long calls are unnecessary and generate slower code. As of this writing, the AIX linker can do this, as can the GNU linker for PowerPC/64. It is planned to add this feature to the GNU linker for 32-bit PowerPC systems as well.
On Darwin/PPC systems, #pragma longcall will generate “jbsr
callee, L42”, plus a “branch island” (glue code). The two target
addresses represent the callee and the “branch island”. The
Darwin/PPC linker will prefer the first address and generate a “bl
callee” if the PPC “bl” instruction will reach the callee directly;
otherwise, the linker will generate “bl L42” to call the “branch
island”. The “branch island” is appended to the body of the
calling function; it computes the full 32-bit address of the callee
and jumps to it.
On Mach-O (Darwin) systems, this option directs the compiler emit to the glue for every direct call, and the Darwin linker decides whether to use or discard it.
In the future, we may cause GCC to ignore all longcall specifications
when the linker is known to generate glue.
-mtls-markers-mno-tls-markers__tls_get_addr with a relocation
specifying the function argument. The relocation allows ld to
reliably associate function call with argument setup instructions for
TLS optimization, which in turn allows gcc to better schedule the
sequence.
-pthread-mrecip-mno-recip-mrecip=opt! to invert the option:
all: enable all estimate instructions,
default: enable the default instructions, equivalent to -mrecip,
none: disable all estimate instructions, equivalent to -mno-recip;
div: enable the reciprocal approximation instructions for both single and double precision;
divf: enable the single-precision reciprocal approximation instructions;
divd: enable the double-precision reciprocal approximation instructions;
rsqrt: enable the reciprocal square root approximation instructions for both single and double precision;
rsqrtf: enable the single-precision reciprocal square root approximation instructions;
rsqrtd: enable the double-precision reciprocal square root approximation instructions;
So for example, -mrecip=all,!rsqrtd would enable the
all of the reciprocal estimate instructions, except for the
FRSQRTE, XSRSQRTEDP, and XVRSQRTEDP instructions
which handle the double-precision reciprocal square root calculations.
-mrecip-precision-mno-recip-precision-mveclibabi=typemass,
which specifies to use IBM's Mathematical Acceleration Subsystem
(MASS) libraries for vectorizing intrinsics using external libraries.
GCC will currently emit calls to acosd2, acosf4,
acoshd2, acoshf4, asind2, asinf4,
asinhd2, asinhf4, atan2d2, atan2f4,
atand2, atanf4, atanhd2, atanhf4,
cbrtd2, cbrtf4, cosd2, cosf4,
coshd2, coshf4, erfcd2, erfcf4,
erfd2, erff4, exp2d2, exp2f4,
expd2, expf4, expm1d2, expm1f4,
hypotd2, hypotf4, lgammad2, lgammaf4,
log10d2, log10f4, log1pd2, log1pf4,
log2d2, log2f4, logd2, logf4,
powd2, powf4, sind2, sinf4, sinhd2,
sinhf4, sqrtd2, sqrtf4, tand2,
tanf4, tanhd2, and tanhf4 when generating code
for power7. Both -ftree-vectorize and
-funsafe-math-optimizations have to be enabled. The MASS
libraries will have to be specified at link time.
-mfriz-mno-frizfriz instruction when the
-funsafe-math-optimizations option is used to optimize
rounding of floating-point values to 64-bit integer and back to floating
point. The friz instruction does not return the same value if
the floating-point number is too large to fit in an integer.
-mpointers-to-nested-functions-mno-pointers-to-nested-functions-msave-toc-indirect-mno-save-toc-indirectThese command-line options are defined for RX targets:
-m64bit-doubles-m32bit-doublesdouble data type be 64 bits (-m64bit-doubles)
or 32 bits (-m32bit-doubles) in size. The default is
-m32bit-doubles. Note RX floating-point hardware only
works on 32-bit values, which is why the default is
-m32bit-doubles.
-fpu-nofpuFloating-point instructions will only be generated for 32-bit floating-point values however, so if the -m64bit-doubles option is in use then the FPU hardware will not be used for doubles.
Note If the -fpu option is enabled then
-funsafe-math-optimizations is also enabled automatically.
This is because the RX FPU instructions are themselves unsafe.
-mcpu=nameThe only difference between RX600 and RX610 is that the
RX610 does not support the MVTIPL instruction.
The RX200 series does not have a hardware floating-point unit
and so -nofpu is enabled by default when this type is
selected.
-mbig-endian-data-mlittle-endian-data-msmall-data-limit=Nr13) is reserved for use pointing to this
area, so it is no longer available for use by the compiler. This
could result in slower and/or larger code if variables which once
could have been held in the reserved register are now pushed onto the
stack.
Note, common variables (variables that have not been initialized) and constants are not placed into the small data area as they are assigned to other sections in the output executable.
The default value is zero, which disables this feature. Note, this
feature is not enabled by default with higher optimization levels
(-O2 etc) because of the potentially detrimental effects of
reserving a register. It is up to the programmer to experiment and
discover whether this feature is of benefit to their program. See the
description of the -mpid option for a description of how the
actual register to hold the small data area pointer is chosen.
-msim-mno-sim-mas100-syntax-mno-as100-syntax-mmax-constant-size=NThe value N can be between 0 and 4. A value of 0 (the default)
or 4 means that constants of any size are allowed.
-mrelax-mint-register=Nr13 will be reserved for the exclusive use
of fast interrupt handlers. A value of 2 reserves r13 and
r12. A value of 3 reserves r13, r12 and
r11, and a value of 4 reserves r13 through r10.
A value of 0, the default, does not reserve any registers.
-msave-acc-in-interrupts-mpid-mno-pidNote, using this feature reserves a register, usually r13, for
the constant data base address. This can result in slower and/or
larger code, especially in complicated functions.
The actual register chosen to hold the constant data base address
depends upon whether the -msmall-data-limit and/or the
-mint-register command-line options are enabled. Starting
with register r13 and proceeding downwards, registers are
allocated first to satisfy the requirements of -mint-register,
then -mpid and finally -msmall-data-limit. Thus it
is possible for the small data area register to be r8 if both
-mint-register=4 and -mpid are specified on the
command line.
By default this feature is not enabled. The default can be restored via the -mno-pid command-line option.
Note: The generic GCC command-line option -ffixed-reg
has special significance to the RX port when used with the
interrupt function attribute. This attribute indicates a
function intended to process fast interrupts. GCC will will ensure
that it only uses the registers r10, r11, r12
and/or r13 and only provided that the normal use of the
corresponding registers have been restricted via the
-ffixed-reg or -mint-register command-line
options.
These are the ‘-m’ options defined for the S/390 and zSeries architecture.
-mhard-float-msoft-float-mhard-dfp-mno-hard-dfp-mlong-double-64-mlong-double-128long double type. A size
of 64 bits makes the long double type equivalent to the double
type. This is the default.
-mbackchain-mno-backchainIn general, code compiled with -mbackchain is call-compatible with code compiled with -mmo-backchain; however, use of the backchain for debugging purposes usually requires that the whole binary is built with -mbackchain. Note that the combination of -mbackchain, -mpacked-stack and -mhard-float is not supported. In order to build a linux kernel use -msoft-float.
The default is to not maintain the backchain.
-mpacked-stack-mno-packed-stackAs long as the stack frame backchain is not used, code generated with -mpacked-stack is call-compatible with code generated with -mno-packed-stack. Note that some non-FSF releases of GCC 2.95 for S/390 or zSeries generated code that uses the stack frame backchain at run time, not just for debugging purposes. Such code is not call-compatible with code compiled with -mpacked-stack. Also, note that the combination of -mbackchain, -mpacked-stack and -mhard-float is not supported. In order to build a linux kernel use -msoft-float.
The default is to not use the packed stack layout.
-msmall-exec-mno-small-execbras instruction
to do subroutine calls.
This only works reliably if the total executable size does not
exceed 64k. The default is to use the basr instruction instead,
which does not have this limitation.
-m64-m31-mzarch-mesa-mmvcle-mno-mvclemvcle instruction
to perform block moves. When -mno-mvcle is specified,
use a mvc loop instead. This is the default unless optimizing for
size.
-mdebug-mno-debug-march=cpu-type-mtune=cpu-type-mtpf-trace-mno-tpf-trace-mfused-madd-mno-fused-madd-mwarn-framesize=framesize-mwarn-dynamicstack-mstack-guard=stack-guard-mstack-size=stack-sizeThese options are defined for Score implementations:
-meb-mel-mnhwloop-muls-mmac-mscore5-mscore5u-mscore7-mscore7dThese ‘-m’ options are defined for the SH implementations:
-m1-m2-m2e-m2a-nofpu-m2a-single-only-m2a-single-m2a-m3-m3e-m4-nofpu-m4-single-only-m4-single-m4-m4a-nofpu-m4a-single-only-m4a-single-m4a-m4al-mb-ml-mdalign-mrelax-mbigtableswitch tables. The default is to use
16-bit offsets.
-mbitops-mfmovdfmovd. Check -mdalign for
alignment constraints.
-mhitachi-mrenesas-mno-renesas-mnomacsaveMAC register as call-clobbered, even if
-mhitachi is given.
-mieee-mno-ieee-minline-ic_invalidate-misize-mpadstruct-msoft-atomicsh-*-linux*.
For details on the atomic built-in functions see __atomic Builtins.
-mspace-mprefergot-musermodesh-*-linux*.
-multcost=number-mdiv=strategy-maccumulate-outgoing-args-mdivsi3_libfunc=name-mfixed-range=register-range-madjust-unroll-mindexed-addressing-mgettrcost=number-mpt-fixed-minvalid-symbols-mbranch-cost=num-mcbranchdicbranchdi4 instruction pattern.
-mcmpeqdicmpeqdi_t instruction pattern even when -mcbranchdi
is in effect.
-mfused-maddfmac instruction (floating-point
multiply-accumulate) if the processor type supports it. Enabling this
option might generate code that produces different numeric floating-point
results compared to strict IEEE 754 arithmetic.
-mpretend-cmoveThese ‘-m’ options are supported on Solaris 2:
-mimpure-text-mimpure-text suppresses the “relocations remain against allocatable but non-writable sections” linker error message. However, the necessary relocations will trigger copy-on-write, and the shared object is not actually shared across processes. Instead of using -mimpure-text, you should compile all source code with -fpic or -fPIC.
These switches are supported in addition to the above on Solaris 2:
-pthreads-pthreadThese ‘-m’ options are supported on the SPARC:
-mno-app-regs-mapp-regsTo be fully SVR4 ABI compliant at the cost of some performance loss,
specify -mno-app-regs. You should compile libraries and system
software with this option.
-mflat-mno-flatWith -mno-flat (the default), the compiler generates save/restore
instructions (except for leaf functions). This is the normal operating mode.
-mfpu-mhard-float-mno-fpu-msoft-float-msoft-float changes the calling convention in the output file;
therefore, it is only useful if you compile all of a program with
this option. In particular, you need to compile libgcc.a, the
library that comes with GCC, with -msoft-float in order for
this to work.
-mhard-quad-float-msoft-quad-floatAs of this writing, there are no SPARC implementations that have hardware
support for the quad-word floating-point instructions. They all invoke
a trap handler for one of these instructions, and then the trap handler
emulates the effect of the instruction. Because of the trap handler overhead,
this is much slower than calling the ABI library routines. Thus the
-msoft-quad-float option is the default.
-mno-unaligned-doubles-munaligned-doublesWith -munaligned-doubles, GCC assumes that doubles have 8-byte
alignment only if they are contained in another type, or if they have an
absolute address. Otherwise, it assumes they have 4-byte alignment.
Specifying this option avoids some rare compatibility problems with code
generated by other compilers. It is not the default because it results
in a performance loss, especially for floating-point code.
-mno-faster-structs-mfaster-structsldd and std instructions for copies in structure
assignment, in place of twice as many ld and st pairs.
However, the use of this changed alignment directly violates the SPARC
ABI. Thus, it's intended only for use on targets where the developer
acknowledges that their resulting code will not be directly in line with
the rules of the ABI.
-mcpu=cpu_typeNative Solaris and GNU/Linux toolchains also support the value ‘native’, which selects the best architecture option for the host processor. -mcpu=native has no effect if GCC does not recognize the processor.
Default instruction scheduling parameters are used for values that select an architecture and not an implementation. These are ‘v7’, ‘v8’, ‘sparclite’, ‘sparclet’, ‘v9’.
Here is a list of each supported architecture and their supported implementations.
By default (unless configured otherwise), GCC generates code for the V7 variant of the SPARC architecture. With -mcpu=cypress, the compiler additionally optimizes it for the Cypress CY7C602 chip, as used in the SPARCStation/SPARCServer 3xx series. This is also appropriate for the older SPARCStation 1, 2, IPX etc.
With -mcpu=v8, GCC generates code for the V8 variant of the SPARC architecture. The only difference from V7 code is that the compiler emits the integer multiply and integer divide instructions which exist in SPARC-V8 but not in SPARC-V7. With -mcpu=supersparc, the compiler additionally optimizes it for the SuperSPARC chip, as used in the SPARCStation 10, 1000 and 2000 series.
With -mcpu=sparclite, GCC generates code for the SPARClite variant of
the SPARC architecture. This adds the integer multiply, integer divide step
and scan (ffs) instructions which exist in SPARClite but not in SPARC-V7.
With -mcpu=f930, the compiler additionally optimizes it for the
Fujitsu MB86930 chip, which is the original SPARClite, with no FPU. With
-mcpu=f934, the compiler additionally optimizes it for the Fujitsu
MB86934 chip, which is the more recent SPARClite with FPU.
With -mcpu=sparclet, GCC generates code for the SPARClet variant of
the SPARC architecture. This adds the integer multiply, multiply/accumulate,
integer divide step and scan (ffs) instructions which exist in SPARClet
but not in SPARC-V7. With -mcpu=tsc701, the compiler additionally
optimizes it for the TEMIC SPARClet chip.
With -mcpu=v9, GCC generates code for the V9 variant of the SPARC
architecture. This adds 64-bit integer and floating-point move instructions,
3 additional floating-point condition code registers and conditional move
instructions. With -mcpu=ultrasparc, the compiler additionally
optimizes it for the Sun UltraSPARC I/II/IIi chips. With
-mcpu=ultrasparc3, the compiler additionally optimizes it for the
Sun UltraSPARC III/III+/IIIi/IIIi+/IV/IV+ chips. With
-mcpu=niagara, the compiler additionally optimizes it for
Sun UltraSPARC T1 chips. With -mcpu=niagara2, the compiler
additionally optimizes it for Sun UltraSPARC T2 chips. With
-mcpu=niagara3, the compiler additionally optimizes it for Sun
UltraSPARC T3 chips. With -mcpu=niagara4, the compiler
additionally optimizes it for Sun UltraSPARC T4 chips.
-mtune=cpu_typeThe same values for -mcpu=cpu_type can be used for
-mtune=cpu_type, but the only useful values are those
that select a particular CPU implementation. Those are ‘cypress’,
‘supersparc’, ‘hypersparc’, ‘leon’, ‘f930’, ‘f934’,
‘sparclite86x’, ‘tsc701’, ‘ultrasparc’, ‘ultrasparc3’,
‘niagara’, ‘niagara2’, ‘niagara3’ and ‘niagara4’. With
native Solaris and GNU/Linux toolchains, ‘native’ can also be used.
-mv8plus-mno-v8plus-mvis-mno-vis-mvis2-mno-vis2-mvis3-mno-vis3-mpopc-mno-popc-mfmaf-mno-fmaf-mfix-at697fThese ‘-m’ options are supported in addition to the above on SPARC-V9 processors in 64-bit environments:
-mlittle-endian-m32-m64-mcmodel=which-mmemory-model=mem-modelThese memory models are formally defined in Appendix D of the Sparc V9
architecture manual, as set in the processor's PSTATE.MM field.
-mstack-bias-mno-stack-biasThese ‘-m’ options are supported on the SPU:
-mwarn-reloc-merror-reloc-msafe-dma-munsafe-dma-mbranch-hints-msmall-mem-mlarge-mem-mstdmainmain, including a
local copy of argv strings.
-mfixed-range=register-range-mea32-mea64__ea named address space qualifier are either 32 or 64
bits wide. The default is 32 bits. As this is an ABI changing option,
all object code in an executable must be compiled with the same setting.
-maddress-space-conversion-mno-address-space-conversion__ea address space as superset
of the generic address space. This enables explicit type casts
between __ea and generic pointer as well as implicit
conversions of generic pointers to __ea pointers. The
default is to allow address space pointer conversions.
-mcache-size=cache-size__ea address space with a particular cache size. Possible
options for cache-size are ‘8’, ‘16’, ‘32’, ‘64’
and ‘128’. The default cache size is 64KB.
-matomic-updates-mno-atomic-updates__ea named address space
qualifier will not interfere with changes to other PPU variables residing
in the same cache line from PPU code. If you do not use atomic updates,
such interference may occur; however, writing back cache lines will be
more efficient. The default behavior is to use atomic updates.
-mdual-nops-mdual-nops=n-mhint-max-nops=n-mhint-max-distance=n-msafe-hintshbrp instruction to make sure
this stall won't happen.
These additional options are available on System V Release 4 for compatibility with other compilers on those systems:
-G-Qy.ident assembler directive in the output.
-Qn.ident directives to the output file (this is
the default).
-YP,dirs-Ym,dirThese ‘-m’ options are supported on the TILE-Gx:
-mcpu=name-m32-m64These ‘-m’ options are supported on the TILEPro:
-mcpu=name-m32These ‘-m’ options are defined for V850 implementations:
-mlong-calls-mno-long-calls-mno-ep-mepep register, and
use the shorter sld and sst instructions. The -mep
option is on by default if you optimize.
-mno-prolog-function-mprolog-function-mspace-mtda=nep points to. The tiny data
area can hold up to 256 bytes in total (128 bytes for byte references).
-msda=ngp points to. The small data
area can hold up to 64 kilobytes.
-mzda=n-mv850-mbig-switch-mapp-regs-mno-app-regs-mv850e2v3-mv850e2-mv850e1-mv850es-mv850eIf neither -mv850 nor -mv850e nor -mv850e1 nor -mv850e2 nor -mv850e2v3 are defined then a default target processor will be chosen and the relevant ‘__v850*__’ preprocessor constant will be defined.
The preprocessor constants ‘__v850’ and ‘__v851__’ are always
defined, regardless of which processor variant is the target.
-mdisable-calltThese ‘-m’ options are defined for the VAX:
-munixaobleq and so on)
that the Unix assembler for the VAX cannot handle across long
ranges.
-mgnu-mgThe options in this section are defined for all VxWorks targets. Options specific to the target hardware are listed with the other options for that target.
-mrtp__RTP__.
-non-static-Bstatic-Bdynamic-Xbind-lazy-Xbind-nowThese are listed under See i386 and x86-64 Options.
These options are defined for Xstormy16:
-msimThese options are supported for Xtensa targets:
-mconst16-mno-const16CONST16 instructions for loading
constant values. The CONST16 instruction is currently not a
standard option from Tensilica. When enabled, CONST16
instructions are always used in place of the standard L32R
instructions. The use of CONST16 is enabled by default only if
the L32R instruction is not available.
-mfused-madd-mno-fused-madd-mserialize-volatile-mno-serialize-volatileMEMW instructions before
volatile memory references to guarantee sequential consistency.
The default is -mserialize-volatile. Use
-mno-serialize-volatile to omit the MEMW instructions.
-mforce-no-pic-mtext-section-literals-mno-text-section-literals-mtarget-align-mno-target-alignLOOP, which the
assembler will always align, either by widening density instructions or
by inserting no-op instructions.
-mlongcalls-mno-longcallsCALL
instruction into an L32R followed by a CALLX instruction.
The default is -mno-longcalls. This option should be used in
programs where the call target can potentially be out of range. This
option is implemented in the assembler, not the compiler, so the
assembly code generated by GCC will still show direct call
instructions—look at the disassembled object code to see the actual
instructions. Note that the assembler will use an indirect call for
every cross-file call, not just those that really will be out of range.
These are listed under See S/390 and zSeries Options.
These machine-independent options control the interface conventions used in code generation.
Most of them have both positive and negative forms; the negative form of -ffoo would be -fno-foo. In the table below, only one of the forms is listed—the one that is not the default. You can figure out the other form by either removing ‘no-’ or adding it.
-fbounds-check-ftrapv-fwrapv-fexceptions-fnon-call-exceptionsSIGALRM.
-funwind-tables-fasynchronous-unwind-tables-fpcc-struct-returnstruct and union values in memory like
longer ones, rather than in registers. This convention is less
efficient, but it has the advantage of allowing intercallability between
GCC-compiled files and files compiled with other compilers, particularly
the Portable C Compiler (pcc).
The precise convention for returning structures in memory depends on the target configuration macros.
Short structures and unions are those whose size and alignment match that of some integer type.
Warning: code compiled with the -fpcc-struct-return
switch is not binary compatible with code compiled with the
-freg-struct-return switch.
Use it to conform to a non-default application binary interface.
-freg-struct-returnstruct and union values in registers when possible.
This is more efficient for small structures than
-fpcc-struct-return.
If you specify neither -fpcc-struct-return nor -freg-struct-return, GCC defaults to whichever convention is standard for the target. If there is no standard convention, GCC defaults to -fpcc-struct-return, except on targets where GCC is the principal compiler. In those cases, we can choose the standard, and we chose the more efficient register return alternative.
Warning: code compiled with the -freg-struct-return
switch is not binary compatible with code compiled with the
-fpcc-struct-return switch.
Use it to conform to a non-default application binary interface.
-fshort-enumsenum type only as many bytes as it needs for the
declared range of possible values. Specifically, the enum type
will be equivalent to the smallest integer type that has enough room.
Warning: the -fshort-enums switch causes GCC to generate
code that is not binary compatible with code generated without that switch.
Use it to conform to a non-default application binary interface.
-fshort-doubledouble as for float.
Warning: the -fshort-double switch causes GCC to generate
code that is not binary compatible with code generated without that switch.
Use it to conform to a non-default application binary interface.
-fshort-wcharWarning: the -fshort-wchar switch causes GCC to generate
code that is not binary compatible with code generated without that switch.
Use it to conform to a non-default application binary interface.
-fno-commonextern) in two different compilations,
you will get a multiple-definition error when you link them.
In this case, you must compile with -fcommon instead.
Compiling with -fno-common is useful on targets for which
it provides better performance, or if you wish to verify that the
program will work on other systems that always treat uninitialized
variable declarations this way.
-fno-ident-finhibit-size-directive.size assembler directive, or anything else that
would cause trouble if the function is split in the middle, and the
two halves are placed at locations far apart in memory. This option is
used when compiling crtstuff.c; you should not need to use it
for anything else.
-fverbose-asm-fno-verbose-asm, the default, causes the
extra information to be omitted and is useful when comparing two assembler
files.
-frecord-gcc-switches-fpicPosition-independent code requires special support, and therefore works only on certain machines. For the 386, GCC supports PIC for System V but not for the Sun 386i. Code generated for the IBM RS/6000 is always position-independent.
When this flag is set, the macros __pic__ and __PIC__
are defined to 1.
-fPICPosition-independent code requires special support, and therefore works only on certain machines.
When this flag is set, the macros __pic__ and __PIC__
are defined to 2.
-fpie-fPIE-fpie and -fPIE both define the macros
__pie__ and __PIE__. The macros have the value 1
for -fpie and 2 for -fPIE.
-fno-jump-tables-ffixed-regreg must be the name of a register. The register names accepted
are machine-specific and are defined in the REGISTER_NAMES
macro in the machine description macro file.
This flag does not have a negative form, because it specifies a
three-way choice.
-fcall-used-regIt is an error to used this flag with the frame pointer or stack pointer. Use of this flag for other registers that have fixed pervasive roles in the machine's execution model will produce disastrous results.
This flag does not have a negative form, because it specifies a
three-way choice.
-fcall-saved-regIt is an error to used this flag with the frame pointer or stack pointer. Use of this flag for other registers that have fixed pervasive roles in the machine's execution model will produce disastrous results.
A different sort of disaster will result from the use of this flag for a register in which function values may be returned.
This flag does not have a negative form, because it specifies a
three-way choice.
-fpack-struct[=n]Warning: the -fpack-struct switch causes GCC to generate
code that is not binary compatible with code generated without that switch.
Additionally, it makes the code suboptimal.
Use it to conform to a non-default application binary interface.
-finstrument-functions__builtin_return_address does not work beyond the current
function, so the call site information may not be available to the
profiling functions otherwise.)
void __cyg_profile_func_enter (void *this_fn,
void *call_site);
void __cyg_profile_func_exit (void *this_fn,
void *call_site);
The first argument is the address of the start of the current function, which may be looked up exactly in the symbol table.
This instrumentation is also done for functions expanded inline in other functions. The profiling calls will indicate where, conceptually, the inline function is entered and exited. This means that addressable versions of such functions must be available. If all your uses of a function are expanded inline, this may mean an additional expansion of code size. If you use ‘extern inline’ in your C code, an addressable version of such functions must be provided. (This is normally the case anyways, but if you get lucky and the optimizer always expands the functions inline, you might have gotten away without providing static copies.)
A function may be given the attribute no_instrument_function, in
which case this instrumentation will not be done. This can be used, for
example, for the profiling functions listed above, high-priority
interrupt routines, and any functions from which the profiling functions
cannot safely be called (perhaps signal handlers, if the profiling
routines generate output or allocate memory).
-finstrument-functions-exclude-file-list=file,file,...-finstrument-functions). If the file that
contains a function definition matches with one of file, then
that function is not instrumented. The match is done on substrings:
if the file parameter is a substring of the file name, it is
considered to be a match.
For example:
-finstrument-functions-exclude-file-list=/bits/stl,include/sys
will exclude any inline function defined in files whose pathnames
contain /bits/stl or include/sys.
If, for some reason, you want to include letter ',' in one of
sym, write '\,'. For example,
-finstrument-functions-exclude-file-list='\,\,tmp'
(note the single quote surrounding the option).
-finstrument-functions-exclude-function-list=sym,sym,...-finstrument-functions-exclude-file-list,
but this option sets the list of function names to be excluded from
instrumentation. The function name to be matched is its user-visible
name, such as vector<int> blah(const vector<int> &), not the
internal mangled name (e.g., _Z4blahRSt6vectorIiSaIiEE). The
match is done on substrings: if the sym parameter is a substring
of the function name, it is considered to be a match. For C99 and C++
extended identifiers, the function name must be given in UTF-8, not
using universal character names.
-fstack-checkNote that this switch does not actually cause checking to be done; the operating system or the language runtime must do that. The switch causes generation of code to ensure that they see the stack being extended.
You can additionally specify a string parameter: no means no
checking, generic means force the use of old-style checking,
specific means use the best checking method and is equivalent
to bare -fstack-check.
Old-style checking is a generic mechanism that requires no specific target support in the compiler but comes with the following drawbacks:
Note that old-style stack checking is also the fallback method for
specific if no target support has been added in the compiler.
-fstack-limit-register=reg-fstack-limit-symbol=sym-fno-stack-limitFor instance, if the stack starts at absolute address ‘0x80000000’
and grows downwards, you can use the flags
-fstack-limit-symbol=__stack_limit and
-Wl,--defsym,__stack_limit=0x7ffe0000 to enforce a stack limit
of 128KB. Note that this may only work with the GNU linker.
-fsplit-stackWhen code compiled with -fsplit-stack calls code compiled
without -fsplit-stack, there may not be much stack space
available for the latter code to run. If compiling all code,
including library code, with -fsplit-stack is not an option,
then the linker can fix up these calls so that the code compiled
without -fsplit-stack always has a large stack. Support for
this is implemented in the gold linker in GNU binutils release 2.21
and later.
-fleading-underscoreWarning: the -fleading-underscore switch causes GCC to
generate code that is not binary compatible with code generated without that
switch. Use it to conform to a non-default application binary interface.
Not all targets provide complete support for this switch.
-ftls-model=modelglobal-dynamic,
local-dynamic, initial-exec or local-exec.
The default without -fpic is initial-exec; with
-fpic the default is global-dynamic.
-fvisibility=default|internal|hidden|protectedDespite the nomenclature, default always means public; i.e.,
available to be linked against from outside the shared object.
protected and internal are pretty useless in real-world
usage so the only other commonly used option will be hidden.
The default if -fvisibility isn't specified is
default, i.e., make every
symbol public—this causes the same behavior as previous versions of
GCC.
A good explanation of the benefits offered by ensuring ELF
symbols have the correct visibility is given by “How To Write
Shared Libraries” by Ulrich Drepper (which can be found at
http://people.redhat.com/~drepper/)—however a superior
solution made possible by this option to marking things hidden when
the default is public is to make the default hidden and mark things
public. This is the norm with DLL's on Windows and with -fvisibility=hidden
and __attribute__ ((visibility("default"))) instead of
__declspec(dllexport) you get almost identical semantics with
identical syntax. This is a great boon to those working with
cross-platform projects.
For those adding visibility support to existing code, you may find ‘#pragma GCC visibility’ of use. This works by you enclosing the declarations you wish to set visibility for with (for example) ‘#pragma GCC visibility push(hidden)’ and ‘#pragma GCC visibility pop’. Bear in mind that symbol visibility should be viewed as part of the API interface contract and thus all new code should always specify visibility when it is not the default; i.e., declarations only for use within the local DSO should always be marked explicitly as hidden as so to avoid PLT indirection overheads—making this abundantly clear also aids readability and self-documentation of the code. Note that due to ISO C++ specification requirements, operator new and operator delete must always be of default visibility.
Be aware that headers from outside your project, in particular system headers and headers from any other library you use, may not be expecting to be compiled with visibility other than the default. You may need to explicitly say ‘#pragma GCC visibility push(default)’ before including any such headers.
‘extern’ declarations are not affected by ‘-fvisibility’, so a lot of code can be recompiled with ‘-fvisibility=hidden’ with no modifications. However, this means that calls to ‘extern’ functions with no explicit visibility will use the PLT, so it is more effective to use ‘__attribute ((visibility))’ and/or ‘#pragma GCC visibility’ to tell the compiler which ‘extern’ declarations should be treated as hidden.
Note that ‘-fvisibility’ does affect C++ vague linkage entities. This means that, for instance, an exception class that will be thrown between DSOs must be explicitly marked with default visibility so that the ‘type_info’ nodes will be unified between the DSOs.
An overview of these techniques, their benefits and how to use them
is at http://gcc.gnu.org/wiki/Visibility.
-fstrict-volatile-bitfieldsIf this option is disabled, the compiler will use the most efficient instruction. In the previous example, that might be a 32-bit load instruction, even though that will access bytes that do not contain any portion of the bit-field, or memory-mapped registers unrelated to the one being updated.
If the target requires strict alignment, and honoring the field
type would require violating this alignment, a warning is issued.
If the field has packed attribute, the access is done without
honoring the field type. If the field doesn't have packed
attribute, the access is done honoring the field type. In both cases,
GCC assumes that the user knows something about the target hardware
that it is unaware of.
The default value of this option is determined by the application binary interface for the target processor.
This section describes several environment variables that affect how GCC operates. Some of them work by specifying directories or prefixes to use when searching for various kinds of files. Some are used to specify other aspects of the compilation environment.
Note that you can also specify places to search using options such as -B, -I and -L (see Directory Options). These take precedence over places specified using environment variables, which in turn take precedence over those specified by the configuration of GCC. See Controlling the Compilation Driver gcc.
The LC_CTYPE environment variable specifies character classification. GCC uses it to determine the character boundaries in a string; this is needed for some multibyte encodings that contain quote and escape characters that would otherwise be interpreted as a string end or escape.
The LC_MESSAGES environment variable specifies the language to use in diagnostic messages.
If the LC_ALL environment variable is set, it overrides the value
of LC_CTYPE and LC_MESSAGES; otherwise, LC_CTYPE
and LC_MESSAGES default to the value of the LANG
environment variable. If none of these variables are set, GCC
defaults to traditional C English behavior.
If GCC_EXEC_PREFIX is not set, GCC will attempt to figure out an appropriate prefix to use based on the pathname it was invoked with.
If GCC cannot find the subprogram using the specified prefix, it tries looking in the usual places for the subprogram.
The default value of GCC_EXEC_PREFIX is
prefix/lib/gcc/ where prefix is the prefix to
the installed compiler. In many cases prefix is the value
of prefix when you ran the configure script.
Other prefixes specified with -B take precedence over this prefix.
This prefix is also used for finding files such as crt0.o that are used for linking.
In addition, the prefix is used in an unusual way in finding the
directories to search for header files. For each of the standard
directories whose name normally begins with ‘/usr/local/lib/gcc’
(more precisely, with the value of GCC_INCLUDE_DIR), GCC tries
replacing that beginning with the specified prefix to produce an
alternate directory name. Thus, with -Bfoo/, GCC will search
foo/bar where it would normally search /usr/local/lib/bar.
These alternate directories are searched first; the standard directories
come next. If a standard directory begins with the configured
prefix then the value of prefix is replaced by
GCC_EXEC_PREFIX when looking for header files.
If LANG is not defined, or if it has some other value, then the compiler will use mblen and mbtowc as defined by the default locale to recognize and translate multibyte characters.
Some additional environments variables affect the behavior of the preprocessor.
PATH_SEPARATOR, is target-dependent and
determined at GCC build time. For Microsoft Windows-based targets it is a
semicolon, and for almost all other targets it is a colon.
CPATH specifies a list of directories to be searched as if specified with -I, but after any paths given with -I options on the command line. This environment variable is used regardless of which language is being preprocessed.
The remaining environment variables apply only when preprocessing the particular language indicated. Each specifies a list of directories to be searched as if specified with -isystem, but after any paths given with -isystem options on the command line.
In all these variables, an empty element instructs the compiler to
search its current working directory. Empty elements can appear at the
beginning or end of a path. For instance, if the value of
CPATH is :/special/include, that has the same
effect as ‘-I. -I/special/include’.
The value of DEPENDENCIES_OUTPUT can be just a file name, in which case the Make rules are written to that file, guessing the target name from the source file name. Or the value can have the form ‘file target’, in which case the rules are written to file file using target as the target name.
In other words, this environment variable is equivalent to combining
the options -MM and -MF
(see Preprocessor Options),
with an optional -MT switch too.
Often large projects have many header files that are included in every source file. The time the compiler takes to process these header files over and over again can account for nearly all of the time required to build the project. To make builds faster, GCC allows users to `precompile' a header file; then, if builds can use the precompiled header file they will be much faster.
To create a precompiled header file, simply compile it as you would any other file, if necessary using the -x option to make the driver treat it as a C or C++ header file. You will probably want to use a tool like make to keep the precompiled header up-to-date when the headers it contains change.
A precompiled header file will be searched for when #include is
seen in the compilation. As it searches for the included file
(see Search Path) the
compiler looks for a precompiled header in each directory just before it
looks for the include file in that directory. The name searched for is
the name specified in the #include with ‘.gch’ appended. If
the precompiled header file can't be used, it is ignored.
For instance, if you have #include "all.h", and you have
all.h.gch in the same directory as all.h, then the
precompiled header file will be used if possible, and the original
header will be used otherwise.
Alternatively, you might decide to put the precompiled header file in a
directory and use -I to ensure that directory is searched
before (or instead of) the directory containing the original header.
Then, if you want to check that the precompiled header file is always
used, you can put a file of the same name as the original header in this
directory containing an #error command.
This also works with -include. So yet another way to use precompiled headers, good for projects not designed with precompiled header files in mind, is to simply take most of the header files used by a project, include them from another header file, precompile that header file, and -include the precompiled header. If the header files have guards against multiple inclusion, they will be skipped because they've already been included (in the precompiled header).
If you need to precompile the same header file for different languages, targets, or compiler options, you can instead make a directory named like all.h.gch, and put each precompiled header in the directory, perhaps using -o. It doesn't matter what you call the files in the directory, every precompiled header in the directory will be considered. The first precompiled header encountered in the directory that is valid for this compilation will be used; they're searched in no particular order.
There are many other possibilities, limited only by your imagination, good sense, and the constraints of your build system.
A precompiled header file can be used only when these conditions apply:
#include.
The -D option is one way to define a macro before a
precompiled header is included; using a #define can also do it.
There are also some options that define macros implicitly, like
-O and -Wdeprecated; the same rule applies to macros
defined this way.
-fexceptions
-fmessage-length= -fpreprocessed -fsched-interblock
-fsched-spec -fsched-spec-load -fsched-spec-load-dangerous
-fsched-verbose=number -fschedule-insns -fvisibility=
-pedantic-errors
For all of these except the last, the compiler will automatically ignore the precompiled header if the conditions aren't met. If you find an option combination that doesn't work and doesn't cause the precompiled header to be ignored, please consider filing a bug report, see Bugs.
If you do use differing options when generating and using the precompiled header, the actual behavior will be a mixture of the behavior for the options. For instance, if you use -g to generate the precompiled header but not when using it, you may or may not get debugging information for routines in the precompiled header.
A conforming implementation of ISO C is required to document its choice of behavior in each of the areas that are designated “implementation defined”. The following lists all such areas, along with the section numbers from the ISO/IEC 9899:1990 and ISO/IEC 9899:1999 standards. Some areas are only implementation-defined in one version of the standard.
Some choices depend on the externally determined ABI for the platform (including standard character encodings) which GCC follows; these are listed as “determined by ABI” below. See Binary Compatibility, and http://gcc.gnu.org/readings.html. Some choices are documented in the preprocessor manual. See Implementation-defined behavior. Some choices are made by the library and operating system (or other environment when compiling for a freestanding environment); refer to their documentation for details.
Diagnostics consist of all the output sent to stderr by GCC.
The behavior of most of these points are dependent on the implementation of the C library, and are not defined by GCC itself.
For internal names, all characters are significant. For external names, the number of significant characters are defined by the linker; for almost all targets, all characters are significant.
This is a property of the linker. C99 requires that case distinctions are always significant in identifiers with external linkage and systems without this property are not supported by GCC.
Determined by ABI.
Determined by ABI.
Determined by ABI.
char object into which has been stored any
character other than a member of the basic execution character set
(C90 6.1.2.5, C99 6.2.5).
Determined by ABI.
signed char or unsigned char has the same
range, representation, and behavior as “plain” char (C90
6.1.2.5, C90 6.2.1.1, C99 6.2.5, C99 6.3.1.1).
Determined by ABI. The options -funsigned-char and -fsigned-char change the default. See Options Controlling C Dialect.
Determined by ABI.
GCC does not support any extended integer types.
GCC supports only two's complement integer types, and all bit patterns are ordinary values.
GCC does not support any extended integer types.
For conversion to a type of width N, the value is reduced modulo 2^N to be within range of the type; no signal is raised.
Bitwise operators act on the representation of the value including both the sign and value bits, where the sign bit is considered immediately above the highest-value value bit. Signed ‘>>’ acts on negative numbers by sign extension.
GCC does not use the latitude given in C99 only to treat certain aspects of signed ‘<<’ as undefined, but this is subject to change.
GCC always follows the C99 requirement that the result of division is truncated towards zero.
<math.h> and <complex.h> that return floating-point
results (C90 and C99 5.2.4.2.2).
The accuracy is unknown.
FLT_ROUNDS
(C90 and C99 5.2.4.2.2).
GCC does not use such values.
FLT_EVAL_METHOD (C99 5.2.4.2.2).
GCC does not use such values.
C99 Annex F is followed.
C99 Annex F is followed.
C99 Annex F is followed.
FP_CONTRACT pragma (C99 6.5).
Expressions are currently only contracted if -funsafe-math-optimizations or -ffast-math are used. This is subject to change.
FENV_ACCESS pragma (C99 7.6.1).
This pragma is not implemented, but the default is to “off” unless -frounding-math is used in which case it is “on”.
This is dependent on the implementation of the C library, and is not defined by GCC itself.
FP_CONTRACT pragma (C99 7.12.2).
This pragma is not implemented. Expressions are currently only contracted if -funsafe-math-optimizations or -ffast-math are used. This is subject to change.
This is dependent on the implementation of the C library, and is not defined by GCC itself.
This is dependent on the implementation of the C library, and is not defined by GCC itself.
A cast from pointer to integer discards most-significant bits if the pointer representation is larger than the integer type, sign-extends2 if the pointer representation is smaller than the integer type, otherwise the bits are unchanged.
A cast from integer to pointer discards most-significant bits if the pointer representation is smaller than the integer type, extends according to the signedness of the integer type if the pointer representation is larger than the integer type, otherwise the bits are unchanged.
When casting from pointer to integer and back again, the resulting pointer must reference the same object as the original pointer, otherwise the behavior is undefined. That is, one may not use integer arithmetic to avoid the undefined behavior of pointer arithmetic as proscribed in C99 6.5.6/8.
The value is as specified in the standard and the type is determined by the ABI.
register
storage-class specifier are effective (C90 6.5.1, C99 6.7.1).
The register specifier affects code generation only in these ways:
register
storage-class specifier; if register is specified, the variable
may have a shorter lifespan than the code would indicate and may never
be placed in memory.
setjmp doesn't save the registers in
all circumstances. In those cases, GCC doesn't allocate any variables
in registers unless they are marked register.
GCC will not inline any functions if the -fno-inline option is used or if -O0 is used. Otherwise, GCC may still be unable to inline a function for many reasons; the -Winline option may be used to determine if a function has not been inlined and why not.
The relevant bytes of the representation of the object are treated as an object of the type used for the access. See Type-punning. This may be a trap representation.
int bit-field is treated as a
signed int bit-field or as an unsigned int bit-field
(C90 6.5.2, C90 6.5.2.1, C99 6.7.2, C99 6.7.2.1).
By default it is treated as signed int but this may be changed
by the -funsigned-bitfields option.
_Bool, signed int,
and unsigned int (C99 6.7.2.1).
No other types are permitted in strictly conforming mode.
Determined by ABI.
Determined by ABI.
Determined by ABI.
Normally, the type is unsigned int if there are no negative
values in the enumeration, otherwise int. If
-fshort-enums is specified, then if there are negative values
it is the first of signed char, short and int
that can represent all the values, otherwise it is the first of
unsigned char, unsigned short and unsigned int
that can represent all the values.
On some targets, -fshort-enums is the default; this is determined by the ABI.
Such an object is normally accessed by pointers and used for accessing hardware. In most expressions, it is intuitively obvious what is a read and what is a write. For example
volatile int *dst = somevalue;
volatile int *src = someothervalue;
*dst = *src;
will cause a read of the volatile object pointed to by src and store the
value into the volatile object pointed to by dst. There is no
guarantee that these reads and writes are atomic, especially for objects
larger than int.
However, if the volatile storage is not being modified, and the value of the volatile storage is not used, then the situation is less obvious. For example
volatile int *src = somevalue;
*src;
According to the C standard, such an expression is an rvalue whose type
is the unqualified version of its original type, i.e. int. Whether
GCC interprets this as a read of the volatile object being pointed to or
only as a request to evaluate the expression for its side-effects depends
on this type.
If it is a scalar type, or on most targets an aggregate type whose only member object is of a scalar type, or a union type whose member objects are of scalar types, the expression is interpreted by GCC as a read of the volatile object; in the other cases, the expression is only evaluated for its side-effects.
GCC is only limited by available memory.
case values in a switch
statement (C90 6.6.4.2).
GCC is only limited by available memory.
See Implementation-defined behavior, for details of these aspects of implementation-defined behavior.
#include directive are combined into a header
name (C90 6.8.2, C99 6.10.2).
#include processing (C90 6.8.2, C99
6.10.2).
STDC #pragma
directive (C90 6.8.6, C99 6.10.6).
See Pragmas, for details of pragmas accepted by GCC on all targets. See Pragmas Accepted by GCC, for details of target-specific pragmas.
__DATE__ and __TIME__ when
respectively, the date and time of translation are not available (C90
6.8.8, C99 6.10.8).
The behavior of most of these points are dependent on the implementation of the C library, and are not defined by GCC itself.
NULL expands
(C90 7.1.6, C99 7.17).
In <stddef.h>, NULL expands to ((void *)0). GCC
does not provide the other headers which define NULL and some
library implementations may use other definitions in those headers.
<float.h>, <limits.h>, and <stdint.h>
(C90 and C99 5.2.4.2, C99 7.18.2, C99 7.18.3).
Determined by ABI.
Determined by ABI.
sizeof operator (C90
6.3.3.4, C99 6.5.3.4).
Determined by ABI.
The behavior of these points are dependent on the implementation of the C library, and are not defined by GCC itself.
A conforming implementation of ISO C++ is required to document its choice of behavior in each of the areas that are designated “implementation defined”. The following lists all such areas, along with the section numbers from the ISO/IEC 14822:1998 and ISO/IEC 14822:2003 standards. Some areas are only implementation-defined in one version of the standard.
Some choices depend on the externally determined ABI for the platform (including standard character encodings) which GCC follows; these are listed as “determined by ABI” below. See Binary Compatibility, and http://gcc.gnu.org/readings.html. Some choices are documented in the preprocessor manual. See Implementation-defined behavior. Some choices are documented in the corresponding document for the C language. See C Implementation. Some choices are made by the library and operating system (or other environment when compiling for a freestanding environment); refer to their documentation for details.
Each implementation shall include documentation that identifies all conditionally-supported constructs that it does not support (C++0x 1.4).
Such argument passing is not supported.
The stack is not unwound before std::terminate is called.
GNU C provides several language features not found in ISO standard C.
(The -pedantic option directs GCC to print a warning message if
any of these features is used.) To test for the availability of these
features in conditional compilation, check for a predefined macro
__GNUC__, which is always defined under GCC.
These extensions are available in C and Objective-C. Most of them are also available in C++. See Extensions to the C++ Language, for extensions that apply only to C++.
Some features that are in ISO C99 but not C90 or C++ are also, as extensions, accepted by GCC in C90 mode and in C++.
A compound statement enclosed in parentheses may appear as an expression in GNU C. This allows you to use loops, switches, and local variables within an expression.
Recall that a compound statement is a sequence of statements surrounded by braces; in this construct, parentheses go around the braces. For example:
({ int y = foo (); int z;
if (y > 0) z = y;
else z = - y;
z; })
is a valid (though slightly more complex than necessary) expression
for the absolute value of foo ().
The last thing in the compound statement should be an expression
followed by a semicolon; the value of this subexpression serves as the
value of the entire construct. (If you use some other kind of statement
last within the braces, the construct has type void, and thus
effectively no value.)
This feature is especially useful in making macro definitions “safe” (so that they evaluate each operand exactly once). For example, the “maximum” function is commonly defined as a macro in standard C as follows:
#define max(a,b) ((a) > (b) ? (a) : (b))
But this definition computes either a or b twice, with bad
results if the operand has side effects. In GNU C, if you know the
type of the operands (here taken as int), you can define
the macro safely as follows:
#define maxint(a,b) \
({int _a = (a), _b = (b); _a > _b ? _a : _b; })
Embedded statements are not allowed in constant expressions, such as the value of an enumeration constant, the width of a bit-field, or the initial value of a static variable.
If you don't know the type of the operand, you can still do this, but you
must use typeof (see Typeof).
In G++, the result value of a statement expression undergoes array and
function pointer decay, and is returned by value to the enclosing
expression. For instance, if A is a class, then
A a;
({a;}).Foo ()
will construct a temporary A object to hold the result of the
statement expression, and that will be used to invoke Foo.
Therefore the this pointer observed by Foo will not be the
address of a.
Any temporaries created within a statement within a statement expression will be destroyed at the statement's end. This makes statement expressions inside macros slightly different from function calls. In the latter case temporaries introduced during argument evaluation will be destroyed at the end of the statement that includes the function call. In the statement expression case they will be destroyed during the statement expression. For instance,
#define macro(a) ({__typeof__(a) b = (a); b + 3; })
template<typename T> T function(T a) { T b = a; return b + 3; }
void foo ()
{
macro (X ());
function (X ());
}
will have different places where temporaries are destroyed. For the
macro case, the temporary X will be destroyed just after
the initialization of b. In the function case that
temporary will be destroyed when the function returns.
These considerations mean that it is probably a bad idea to use statement-expressions of this form in header files that are designed to work with C++. (Note that some versions of the GNU C Library contained header files using statement-expression that lead to precisely this bug.)
Jumping into a statement expression with goto or using a
switch statement outside the statement expression with a
case or default label inside the statement expression is
not permitted. Jumping into a statement expression with a computed
goto (see Labels as Values) yields undefined behavior.
Jumping out of a statement expression is permitted, but if the
statement expression is part of a larger expression then it is
unspecified which other subexpressions of that expression have been
evaluated except where the language definition requires certain
subexpressions to be evaluated before or after the statement
expression. In any case, as with a function call the evaluation of a
statement expression is not interleaved with the evaluation of other
parts of the containing expression. For example,
foo (), (({ bar1 (); goto a; 0; }) + bar2 ()), baz();
will call foo and bar1 and will not call baz but
may or may not call bar2. If bar2 is called, it will be
called after foo and before bar1
GCC allows you to declare local labels in any nested block
scope. A local label is just like an ordinary label, but you can
only reference it (with a goto statement, or by taking its
address) within the block in which it was declared.
A local label declaration looks like this:
__label__ label;
or
__label__ label1, label2, /* ... */;
Local label declarations must come at the beginning of the block, before any ordinary declarations or statements.
The label declaration defines the label name, but does not define
the label itself. You must do this in the usual way, with
label:, within the statements of the statement expression.
The local label feature is useful for complex macros. If a macro
contains nested loops, a goto can be useful for breaking out of
them. However, an ordinary label whose scope is the whole function
cannot be used: if the macro can be expanded several times in one
function, the label will be multiply defined in that function. A
local label avoids this problem. For example:
#define SEARCH(value, array, target) \
do { \
__label__ found; \
typeof (target) _SEARCH_target = (target); \
typeof (*(array)) *_SEARCH_array = (array); \
int i, j; \
int value; \
for (i = 0; i < max; i++) \
for (j = 0; j < max; j++) \
if (_SEARCH_array[i][j] == _SEARCH_target) \
{ (value) = i; goto found; } \
(value) = -1; \
found:; \
} while (0)
This could also be written using a statement-expression:
#define SEARCH(array, target) \
({ \
__label__ found; \
typeof (target) _SEARCH_target = (target); \
typeof (*(array)) *_SEARCH_array = (array); \
int i, j; \
int value; \
for (i = 0; i < max; i++) \
for (j = 0; j < max; j++) \
if (_SEARCH_array[i][j] == _SEARCH_target) \
{ value = i; goto found; } \
value = -1; \
found: \
value; \
})
Local label declarations also make the labels they declare visible to nested functions, if there are any. See Nested Functions, for details.
You can get the address of a label defined in the current function
(or a containing function) with the unary operator ‘&&’. The
value has type void *. This value is a constant and can be used
wherever a constant of that type is valid. For example:
void *ptr;
/* ... */
ptr = &&foo;
To use these values, you need to be able to jump to one. This is done
with the computed goto statement3, goto *exp;. For example,
goto *ptr;
Any expression of type void * is allowed.
One way of using these constants is in initializing a static array that will serve as a jump table:
static void *array[] = { &&foo, &&bar, &&hack };
Then you can select a label with indexing, like this:
goto *array[i];
Note that this does not check whether the subscript is in bounds—array indexing in C never does that.
Such an array of label values serves a purpose much like that of the
switch statement. The switch statement is cleaner, so
use that rather than an array unless the problem does not fit a
switch statement very well.
Another use of label values is in an interpreter for threaded code. The labels within the interpreter function can be stored in the threaded code for super-fast dispatching.
You may not use this mechanism to jump to code in a different function. If you do that, totally unpredictable things will happen. The best way to avoid this is to store the label address only in automatic variables and never pass it as an argument.
An alternate way to write the above example is
static const int array[] = { &&foo - &&foo, &&bar - &&foo,
&&hack - &&foo };
goto *(&&foo + array[i]);
This is more friendly to code living in shared libraries, as it reduces the number of dynamic relocations that are needed, and by consequence, allows the data to be read-only.
The &&foo expressions for the same label might have different
values if the containing function is inlined or cloned. If a program
relies on them being always the same,
__attribute__((__noinline__,__noclone__)) should be used to
prevent inlining and cloning. If &&foo is used in a static
variable initializer, inlining and cloning is forbidden.
A nested function is a function defined inside another function.
(Nested functions are not supported for GNU C++.) The nested function's
name is local to the block where it is defined. For example, here we
define a nested function named square, and call it twice:
foo (double a, double b)
{
double square (double z) { return z * z; }
return square (a) + square (b);
}
The nested function can access all the variables of the containing
function that are visible at the point of its definition. This is
called lexical scoping. For example, here we show a nested
function which uses an inherited variable named offset:
bar (int *array, int offset, int size)
{
int access (int *array, int index)
{ return array[index + offset]; }
int i;
/* ... */
for (i = 0; i < size; i++)
/* ... */ access (array, i) /* ... */
}
Nested function definitions are permitted within functions in the places where variable definitions are allowed; that is, in any block, mixed with the other declarations and statements in the block.
It is possible to call the nested function from outside the scope of its name by storing its address or passing the address to another function:
hack (int *array, int size)
{
void store (int index, int value)
{ array[index] = value; }
intermediate (store, size);
}
Here, the function intermediate receives the address of
store as an argument. If intermediate calls store,
the arguments given to store are used to store into array.
But this technique works only so long as the containing function
(hack, in this example) does not exit.
If you try to call the nested function through its address after the containing function has exited, all hell will break loose. If you try to call it after a containing scope level has exited, and if it refers to some of the variables that are no longer in scope, you may be lucky, but it's not wise to take the risk. If, however, the nested function does not refer to anything that has gone out of scope, you should be safe.
GCC implements taking the address of a nested function using a technique called trampolines. This technique was described in Lexical Closures for C++ (Thomas M. Breuel, USENIX C++ Conference Proceedings, October 17-21, 1988).
A nested function can jump to a label inherited from a containing
function, provided the label was explicitly declared in the containing
function (see Local Labels). Such a jump returns instantly to the
containing function, exiting the nested function which did the
goto and any intermediate functions as well. Here is an example:
bar (int *array, int offset, int size)
{
__label__ failure;
int access (int *array, int index)
{
if (index > size)
goto failure;
return array[index + offset];
}
int i;
/* ... */
for (i = 0; i < size; i++)
/* ... */ access (array, i) /* ... */
/* ... */
return 0;
/* Control comes here from access
if it detects an error. */
failure:
return -1;
}
A nested function always has no linkage. Declaring one with
extern or static is erroneous. If you need to declare the nested function
before its definition, use auto (which is otherwise meaningless
for function declarations).
bar (int *array, int offset, int size)
{
__label__ failure;
auto int access (int *, int);
/* ... */
int access (int *array, int index)
{
if (index > size)
goto failure;
return array[index + offset];
}
/* ... */
}
Using the built-in functions described below, you can record the arguments a function received, and call another function with the same arguments, without knowing the number or types of the arguments.
You can also record the return value of that function call, and later return that value, without knowing what data type the function tried to return (as long as your caller expects that data type).
However, these built-in functions may interact badly with some sophisticated features or other extensions of the language. It is, therefore, not recommended to use them outside very simple functions acting as mere forwarders for their arguments.
This built-in function returns a pointer to data describing how to perform a call with the same arguments as were passed to the current function.
The function saves the arg pointer register, structure value address, and all registers that might be used to pass arguments to a function into a block of memory allocated on the stack. Then it returns the address of that block.
This built-in function invokes function with a copy of the parameters described by arguments and size.
The value of arguments should be the value returned by
__builtin_apply_args. The argument size specifies the size of the stack argument data, in bytes.This function returns a pointer to data describing how to return whatever value was returned by function. The data is saved in a block of memory allocated on the stack.
It is not always simple to compute the proper value for size. The value is used by
__builtin_applyto compute the amount of data that should be pushed on the stack and copied from the incoming argument area.
This built-in function returns the value described by result from the containing function. You should specify, for result, a value returned by
__builtin_apply.
This built-in function represents all anonymous arguments of an inline function. It can be used only in inline functions which will be always inlined, never compiled as a separate function, such as those using
__attribute__ ((__always_inline__))or__attribute__ ((__gnu_inline__))extern inline functions. It must be only passed as last argument to some other function with variable arguments. This is useful for writing small wrapper inlines for variable argument functions, when using preprocessor macros is undesirable. For example:extern int myprintf (FILE *f, const char *format, ...); extern inline __attribute__ ((__gnu_inline__)) int myprintf (FILE *f, const char *format, ...) { int r = fprintf (f, "myprintf: "); if (r < 0) return r; int s = fprintf (f, format, __builtin_va_arg_pack ()); if (s < 0) return s; return r + s; }
This built-in function returns the number of anonymous arguments of an inline function. It can be used only in inline functions which will be always inlined, never compiled as a separate function, such as those using
__attribute__ ((__always_inline__))or__attribute__ ((__gnu_inline__))extern inline functions. For example following will do link or runtime checking of open arguments for optimized code:#ifdef __OPTIMIZE__ extern inline __attribute__((__gnu_inline__)) int myopen (const char *path, int oflag, ...) { if (__builtin_va_arg_pack_len () > 1) warn_open_too_many_arguments (); if (__builtin_constant_p (oflag)) { if ((oflag & O_CREAT) != 0 && __builtin_va_arg_pack_len () < 1) { warn_open_missing_mode (); return __open_2 (path, oflag); } return open (path, oflag, __builtin_va_arg_pack ()); } if (__builtin_va_arg_pack_len () < 1) return __open_2 (path, oflag); return open (path, oflag, __builtin_va_arg_pack ()); } #endif
typeof
Another way to refer to the type of an expression is with typeof.
The syntax of using of this keyword looks like sizeof, but the
construct acts semantically like a type name defined with typedef.
There are two ways of writing the argument to typeof: with an
expression or with a type. Here is an example with an expression:
typeof (x[0](1))
This assumes that x is an array of pointers to functions;
the type described is that of the values of the functions.
Here is an example with a typename as the argument:
typeof (int *)
Here the type described is that of pointers to int.
If you are writing a header file that must work when included in ISO C
programs, write __typeof__ instead of typeof.
See Alternate Keywords.
A typeof-construct can be used anywhere a typedef name could be
used. For example, you can use it in a declaration, in a cast, or inside
of sizeof or typeof.
The operand of typeof is evaluated for its side effects if and
only if it is an expression of variably modified type or the name of
such a type.
typeof is often useful in conjunction with the
statements-within-expressions feature. Here is how the two together can
be used to define a safe “maximum” macro that operates on any
arithmetic type and evaluates each of its arguments exactly once:
#define max(a,b) \
({ typeof (a) _a = (a); \
typeof (b) _b = (b); \
_a > _b ? _a : _b; })
The reason for using names that start with underscores for the local
variables is to avoid conflicts with variable names that occur within the
expressions that are substituted for a and b. Eventually we
hope to design a new form of declaration syntax that allows you to declare
variables whose scopes start only after their initializers; this will be a
more reliable way to prevent such conflicts.
Some more examples of the use of typeof:
y with the type of what x points to.
typeof (*x) y;
y as an array of such values.
typeof (*x) y[4];
y as an array of pointers to characters:
typeof (typeof (char *)[4]) y;
It is equivalent to the following traditional C declaration:
char *y[4];
To see the meaning of the declaration using typeof, and why it
might be a useful way to write, rewrite it with these macros:
#define pointer(T) typeof(T *)
#define array(T, N) typeof(T [N])
Now the declaration can be rewritten this way:
array (pointer (char), 4) y;
Thus, array (pointer (char), 4) is the type of arrays of 4
pointers to char.
Compatibility Note: In addition to typeof, GCC 2 supported
a more limited extension which permitted one to write
typedef T = expr;
with the effect of declaring T to have the type of the expression
expr. This extension does not work with GCC 3 (versions between
3.0 and 3.2 will crash; 3.2.1 and later give an error). Code which
relies on it should be rewritten to use typeof:
typedef typeof(expr) T;
This will work with all versions of GCC.
The middle operand in a conditional expression may be omitted. Then if the first operand is nonzero, its value is the value of the conditional expression.
Therefore, the expression
x ? : y
has the value of x if that is nonzero; otherwise, the value of
y.
This example is perfectly equivalent to
x ? x : y
In this simple case, the ability to omit the middle operand is not especially useful. When it becomes useful is when the first operand does, or may (if it is a macro argument), contain a side effect. Then repeating the operand in the middle would perform the side effect twice. Omitting the middle operand uses the value already computed without the undesirable effects of recomputing it.
As an extension the integer scalar type __int128 is supported for
targets having an integer mode wide enough to hold 128-bit.
Simply write __int128 for a signed 128-bit integer, or
unsigned __int128 for an unsigned 128-bit integer. There is no
support in GCC to express an integer constant of type __int128
for targets having long long integer with less then 128 bit width.
ISO C99 supports data types for integers that are at least 64 bits wide,
and as an extension GCC supports them in C90 mode and in C++.
Simply write long long int for a signed integer, or
unsigned long long int for an unsigned integer. To make an
integer constant of type long long int, add the suffix ‘LL’
to the integer. To make an integer constant of type unsigned long
long int, add the suffix ‘ULL’ to the integer.
You can use these types in arithmetic like any other integer types. Addition, subtraction, and bitwise boolean operations on these types are open-coded on all types of machines. Multiplication is open-coded if the machine supports fullword-to-doubleword a widening multiply instruction. Division and shifts are open-coded only on machines that provide special support. The operations that are not open-coded use special library routines that come with GCC.
There may be pitfalls when you use long long types for function
arguments, unless you declare function prototypes. If a function
expects type int for its argument, and you pass a value of type
long long int, confusion will result because the caller and the
subroutine will disagree about the number of bytes for the argument.
Likewise, if the function expects long long int and you pass
int. The best way to avoid such problems is to use prototypes.
ISO C99 supports complex floating data types, and as an extension GCC
supports them in C90 mode and in C++, and supports complex integer data
types which are not part of ISO C99. You can declare complex types
using the keyword _Complex. As an extension, the older GNU
keyword __complex__ is also supported.
For example, ‘_Complex double x;’ declares x as a
variable whose real part and imaginary part are both of type
double. ‘_Complex short int y;’ declares y to
have real and imaginary parts of type short int; this is not
likely to be useful, but it shows that the set of complex types is
complete.
To write a constant with a complex data type, use the suffix ‘i’ or
‘j’ (either one; they are equivalent). For example, 2.5fi
has type _Complex float and 3i has type
_Complex int. Such a constant always has a pure imaginary
value, but you can form any complex value you like by adding one to a
real constant. This is a GNU extension; if you have an ISO C99
conforming C library (such as GNU libc), and want to construct complex
constants of floating type, you should include <complex.h> and
use the macros I or _Complex_I instead.
To extract the real part of a complex-valued expression exp, write
__real__ exp. Likewise, use __imag__ to
extract the imaginary part. This is a GNU extension; for values of
floating type, you should use the ISO C99 functions crealf,
creal, creall, cimagf, cimag and
cimagl, declared in <complex.h> and also provided as
built-in functions by GCC.
The operator ‘~’ performs complex conjugation when used on a value
with a complex type. This is a GNU extension; for values of
floating type, you should use the ISO C99 functions conjf,
conj and conjl, declared in <complex.h> and also
provided as built-in functions by GCC.
GCC can allocate complex automatic variables in a noncontiguous
fashion; it's even possible for the real part to be in a register while
the imaginary part is on the stack (or vice-versa). Only the DWARF2
debug info format can represent this, so use of DWARF2 is recommended.
If you are using the stabs debug info format, GCC describes a noncontiguous
complex variable as if it were two separate variables of noncomplex type.
If the variable's actual name is foo, the two fictitious
variables are named foo$real and foo$imag. You can
examine and set these two fictitious variables with your debugger.
As an extension, the GNU C compiler supports additional floating
types, __float80 and __float128 to support 80bit
(XFmode) and 128 bit (TFmode) floating types.
Support for additional types includes the arithmetic operators:
add, subtract, multiply, divide; unary arithmetic operators;
relational operators; equality operators; and conversions to and from
integer and other floating types. Use a suffix ‘w’ or ‘W’
in a literal constant of type __float80 and ‘q’ or ‘Q’
for _float128. You can declare complex types using the
corresponding internal complex type, XCmode for __float80
type and TCmode for __float128 type:
typedef _Complex float __attribute__((mode(TC))) _Complex128;
typedef _Complex float __attribute__((mode(XC))) _Complex80;
Not all targets support additional floating point types. __float80
and __float128 types are supported on i386, x86_64 and ia64 targets.
The __float128 type is supported on hppa HP-UX targets.
On ARM targets, GCC supports half-precision (16-bit) floating point via
the __fp16 type. You must enable this type explicitly
with the -mfp16-format command-line option in order to use it.
ARM supports two incompatible representations for half-precision floating-point values. You must choose one of the representations and use it consistently in your program.
Specifying -mfp16-format=ieee selects the IEEE 754-2008 format. This format can represent normalized values in the range of 2^-14 to 65504. There are 11 bits of significand precision, approximately 3 decimal digits.
Specifying -mfp16-format=alternative selects the ARM alternative format. This representation is similar to the IEEE format, but does not support infinities or NaNs. Instead, the range of exponents is extended, so that this format can represent normalized values in the range of 2^-14 to 131008.
The __fp16 type is a storage format only. For purposes
of arithmetic and other operations, __fp16 values in C or C++
expressions are automatically promoted to float. In addition,
you cannot declare a function with a return value or parameters
of type __fp16.
Note that conversions from double to __fp16
involve an intermediate conversion to float. Because
of rounding, this can sometimes produce a different result than a
direct conversion.
ARM provides hardware support for conversions between
__fp16 and float values
as an extension to VFP and NEON (Advanced SIMD). GCC generates
code using these hardware instructions if you compile with
options to select an FPU that provides them;
for example, -mfpu=neon-fp16 -mfloat-abi=softfp,
in addition to the -mfp16-format option to select
a half-precision format.
Language-level support for the __fp16 data type is
independent of whether GCC generates code using hardware floating-point
instructions. In cases where hardware support is not specified, GCC
implements conversions between __fp16 and float values
as library calls.
As an extension, the GNU C compiler supports decimal floating types as defined in the N1312 draft of ISO/IEC WDTR24732. Support for decimal floating types in GCC will evolve as the draft technical report changes. Calling conventions for any target might also change. Not all targets support decimal floating types.
The decimal floating types are _Decimal32, _Decimal64, and
_Decimal128. They use a radix of ten, unlike the floating types
float, double, and long double whose radix is not
specified by the C standard but is usually two.
Support for decimal floating types includes the arithmetic operators
add, subtract, multiply, divide; unary arithmetic operators;
relational operators; equality operators; and conversions to and from
integer and other floating types. Use a suffix ‘df’ or
‘DF’ in a literal constant of type _Decimal32, ‘dd’
or ‘DD’ for _Decimal64, and ‘dl’ or ‘DL’ for
_Decimal128.
GCC support of decimal float as specified by the draft technical report is incomplete:
__STDC_DEC_FP__ to indicate that the implementation conforms to
the technical report.
Types _Decimal32, _Decimal64, and _Decimal128
are supported by the DWARF2 debug information format.
ISO C99 supports floating-point numbers written not only in the usual
decimal notation, such as 1.55e1, but also numbers such as
0x1.fp3 written in hexadecimal format. As a GNU extension, GCC
supports this in C90 mode (except in some cases when strictly
conforming) and in C++. In that format the
‘0x’ hex introducer and the ‘p’ or ‘P’ exponent field are
mandatory. The exponent is a decimal number that indicates the power of
2 by which the significant part will be multiplied. Thus ‘0x1.f’ is
1 15/16,
‘p3’ multiplies it by 8, and the value of 0x1.fp3
is the same as 1.55e1.
Unlike for floating-point numbers in the decimal notation the exponent
is always required in the hexadecimal notation. Otherwise the compiler
would not be able to resolve the ambiguity of, e.g., 0x1.f. This
could mean 1.0f or 1.9375 since ‘f’ is also the
extension for floating-point constants of type float.
As an extension, the GNU C compiler supports fixed-point types as defined in the N1169 draft of ISO/IEC DTR 18037. Support for fixed-point types in GCC will evolve as the draft technical report changes. Calling conventions for any target might also change. Not all targets support fixed-point types.
The fixed-point types are
short _Fract,
_Fract,
long _Fract,
long long _Fract,
unsigned short _Fract,
unsigned _Fract,
unsigned long _Fract,
unsigned long long _Fract,
_Sat short _Fract,
_Sat _Fract,
_Sat long _Fract,
_Sat long long _Fract,
_Sat unsigned short _Fract,
_Sat unsigned _Fract,
_Sat unsigned long _Fract,
_Sat unsigned long long _Fract,
short _Accum,
_Accum,
long _Accum,
long long _Accum,
unsigned short _Accum,
unsigned _Accum,
unsigned long _Accum,
unsigned long long _Accum,
_Sat short _Accum,
_Sat _Accum,
_Sat long _Accum,
_Sat long long _Accum,
_Sat unsigned short _Accum,
_Sat unsigned _Accum,
_Sat unsigned long _Accum,
_Sat unsigned long long _Accum.
Fixed-point data values contain fractional and optional integral parts. The format of fixed-point data varies and depends on the target machine.
Support for fixed-point types includes:
++, --)
+, -, !)
+, -, *, /)
<<, >>)
<, <=, >=, >)
==, !=)
+=, -=, *=, /=,
<<=, >>=)
Use a suffix in a fixed-point literal constant:
short _Fract and
_Sat short _Fract
_Fract and _Sat _Fract
long _Fract and
_Sat long _Fract
long long _Fract and
_Sat long long _Fract
unsigned short _Fract and
_Sat unsigned short _Fract
unsigned _Fract and
_Sat unsigned _Fract
unsigned long _Fract and
_Sat unsigned long _Fract
unsigned long long _Fract
and _Sat unsigned long long _Fract
short _Accum and
_Sat short _Accum
_Accum and _Sat _Accum
long _Accum and
_Sat long _Accum
long long _Accum and
_Sat long long _Accum
unsigned short _Accum and
_Sat unsigned short _Accum
unsigned _Accum and
_Sat unsigned _Accum
unsigned long _Accum and
_Sat unsigned long _Accum
unsigned long long _Accum
and _Sat unsigned long long _Accum
GCC support of fixed-point types as specified by the draft technical report is incomplete:
Fixed-point types are supported by the DWARF2 debug information format.
As an extension, the GNU C compiler supports named address spaces as defined in the N1275 draft of ISO/IEC DTR 18037. Support for named address spaces in GCC will evolve as the draft technical report changes. Calling conventions for any target might also change. At present, only the AVR, SPU, M32C, and RL78 targets support address spaces other than the generic address space.
Address space identifiers may be used exactly like any other C type
qualifier (e.g., const or volatile). See the N1275
document for more details.
On the AVR target, there are several address spaces that can be used
in order to put read-only data into the flash memory and access that
data by means of the special instructions LPM or ELPM
needed to read from flash.
Per default, any data including read-only data is located in RAM (the generic address space) so that non-generic address spaces are needed to locate read-only data in flash memory and to generate the right instructions to access this data without using (inline) assembler code.
__flash__flash qualifier will locate data in the
.progmem.data section. Data will be read using the LPM
instruction. Pointers to this address space are 16 bits wide.
__flash1__flash2__flash3__flash4__flash5.progmemN.data where N refers to
address space __flashN.
The compiler will set the RAMPZ segment register approptiately
before reading data by means of the ELPM instruction.
__memxRAMPZ set according to the high byte of the address.
Objects in this address space will be located in .progmem.data.
Example
char my_read (const __flash char ** p)
{
/* p is a pointer to RAM that points to a pointer to flash.
The first indirection of p will read that flash pointer
from RAM and the second indirection reads a char from this
flash address. */
return **p;
}
/* Locate array[] in flash memory */
const __flash int array[] = { 3, 5, 7, 11, 13, 17, 19 };
int i = 1;
int main (void)
{
/* Return 17 by reading from flash memory */
return array[array[i]];
}
For each named address space supported by avr-gcc there is an equally named but uppercase built-in macro defined. The purpose is to facilitate testing if respective address space support is available or not:
#ifdef __FLASH
const __flash int var = 1;
int read_var (void)
{
return var;
}
#else
#include <avr/pgmspace.h> /* From AVR-LibC */
const int var PROGMEM = 1;
int read_var (void)
{
return (int) pgm_read_word (&var);
}
#endif /* __FLASH */
Notice that attribute progmem
locates data in flash but
accesses to these data will read from generic address space, i.e.
from RAM,
so that you need special accessors like pgm_read_byte
from AVR-LibC
together with attribute progmem.
Limitations and caveats
__flash or __flashN address spaces
will show undefined behaviour. The only address space that
supports reading across the 64 KiB flash segment boundaries is
__memx.
__flashN address spaces
you will have to arrange your linker skript to locate the
.progmemN.data sections according to your needs.
const, i.e. as read-only data.
This still applies if the data in one of these address
spaces like software version number or calibration lookup table are intended to
be changed after load time by, say, a boot loader. In this case
the right qualification is const volatile so that the compiler
must not optimize away known values or insert them
as immediates into operands of instructions.
extern const __memx char foo;
const __memx void *pfoo = &foo;
The code will throw an assembler warning and the high byte of
pfoo will be initialized with 0, i.e. the
initialization will be as if foo was located in the first
64 KiB chunk of flash.
On the M32C target, with the R8C and M16C cpu variants, variables
qualified with __far are accessed using 32-bit addresses in
order to access memory beyond the first 64 Ki bytes. If
__far is used with the M32CM or M32C cpu variants, it has no
effect.
On the RL78 target, variables qualified with __far are accessed
with 32-bit pointers (20-bit addresses) rather than the default 16-bit
addresses. Non-far variables are assumed to appear in the topmost
64 KiB of the address space.
On the SPU target variables may be declared as
belonging to another address space by qualifying the type with the
__ea address space identifier:
extern int __ea i;
When the variable i is accessed, the compiler will generate
special code to access this variable. It may use runtime library
support, or generate special machine instructions to access that address
space.
Zero-length arrays are allowed in GNU C. They are very useful as the last element of a structure which is really a header for a variable-length object:
struct line {
int length;
char contents[0];
};
struct line *thisline = (struct line *)
malloc (sizeof (struct line) + this_length);
thisline->length = this_length;
In ISO C90, you would have to give contents a length of 1, which
means either you waste space or complicate the argument to malloc.
In ISO C99, you would use a flexible array member, which is slightly different in syntax and semantics:
contents[] without
the 0.
sizeof
operator may not be applied. As a quirk of the original implementation
of zero-length arrays, sizeof evaluates to zero.
struct that is otherwise non-empty.
GCC versions before 3.0 allowed zero-length arrays to be statically initialized, as if they were flexible arrays. In addition to those cases that were useful, it also allowed initializations in situations that would corrupt later data. Non-empty initialization of zero-length arrays is now treated like any case where there are more initializer elements than the array holds, in that a suitable warning about "excess elements in array" is given, and the excess elements (all of them, in this case) are ignored.
Instead GCC allows static initialization of flexible array members.
This is equivalent to defining a new structure containing the original
structure followed by an array of sufficient size to contain the data.
I.e. in the following, f1 is constructed as if it were declared
like f2.
struct f1 {
int x; int y[];
} f1 = { 1, { 2, 3, 4 } };
struct f2 {
struct f1 f1; int data[3];
} f2 = { { 1 }, { 2, 3, 4 } };
The convenience of this extension is that f1 has the desired
type, eliminating the need to consistently refer to f2.f1.
This has symmetry with normal static arrays, in that an array of
unknown size is also written with [].
Of course, this extension only makes sense if the extra data comes at the end of a top-level object, as otherwise we would be overwriting data at subsequent offsets. To avoid undue complication and confusion with initialization of deeply nested arrays, we simply disallow any non-empty initialization except when the structure is the top-level object. For example:
struct foo { int x; int y[]; };
struct bar { struct foo z; };
struct foo a = { 1, { 2, 3, 4 } }; // Valid.
struct bar b = { { 1, { 2, 3, 4 } } }; // Invalid.
struct bar c = { { 1, { } } }; // Valid.
struct foo d[1] = { { 1 { 2, 3, 4 } } }; // Invalid.
GCC permits a C structure to have no members:
struct empty {
};
The structure will have size zero. In C++, empty structures are part
of the language. G++ treats empty structures as if they had a single
member of type char.
Variable-length automatic arrays are allowed in ISO C99, and as an extension GCC accepts them in C90 mode and in C++. These arrays are declared like any other automatic arrays, but with a length that is not a constant expression. The storage is allocated at the point of declaration and deallocated when the brace-level is exited. For example:
FILE *
concat_fopen (char *s1, char *s2, char *mode)
{
char str[strlen (s1) + strlen (s2) + 1];
strcpy (str, s1);
strcat (str, s2);
return fopen (str, mode);
}
Jumping or breaking out of the scope of the array name deallocates the storage. Jumping into the scope is not allowed; you get an error message for it.
You can use the function alloca to get an effect much like
variable-length arrays. The function alloca is available in
many other C implementations (but not in all). On the other hand,
variable-length arrays are more elegant.
There are other differences between these two methods. Space allocated
with alloca exists until the containing function returns.
The space for a variable-length array is deallocated as soon as the array
name's scope ends. (If you use both variable-length arrays and
alloca in the same function, deallocation of a variable-length array
will also deallocate anything more recently allocated with alloca.)
You can also use variable-length arrays as arguments to functions:
struct entry
tester (int len, char data[len][len])
{
/* ... */
}
The length of an array is computed once when the storage is allocated
and is remembered for the scope of the array in case you access it with
sizeof.
If you want to pass the array first and the length afterward, you can use a forward declaration in the parameter list—another GNU extension.
struct entry
tester (int len; char data[len][len], int len)
{
/* ... */
}
The ‘int len’ before the semicolon is a parameter forward
declaration, and it serves the purpose of making the name len
known when the declaration of data is parsed.
You can write any number of such parameter forward declarations in the parameter list. They can be separated by commas or semicolons, but the last one must end with a semicolon, which is followed by the “real” parameter declarations. Each forward declaration must match a “real” declaration in parameter name and data type. ISO C99 does not support parameter forward declarations.
In the ISO C standard of 1999, a macro can be declared to accept a variable number of arguments much as a function can. The syntax for defining the macro is similar to that of a function. Here is an example:
#define debug(format, ...) fprintf (stderr, format, __VA_ARGS__)
Here ‘...’ is a variable argument. In the invocation of
such a macro, it represents the zero or more tokens until the closing
parenthesis that ends the invocation, including any commas. This set of
tokens replaces the identifier __VA_ARGS__ in the macro body
wherever it appears. See the CPP manual for more information.
GCC has long supported variadic macros, and used a different syntax that allowed you to give a name to the variable arguments just like any other argument. Here is an example:
#define debug(format, args...) fprintf (stderr, format, args)
This is in all ways equivalent to the ISO C example above, but arguably more readable and descriptive.
GNU CPP has two further variadic macro extensions, and permits them to be used with either of the above forms of macro definition.
In standard C, you are not allowed to leave the variable argument out entirely; but you are allowed to pass an empty argument. For example, this invocation is invalid in ISO C, because there is no comma after the string:
debug ("A message")
GNU CPP permits you to completely omit the variable arguments in this way. In the above examples, the compiler would complain, though since the expansion of the macro still has the extra comma after the format string.
To help solve this problem, CPP behaves specially for variable arguments used with the token paste operator, ‘##’. If instead you write
#define debug(format, ...) fprintf (stderr, format, ## __VA_ARGS__)
and if the variable arguments are omitted or empty, the ‘##’ operator causes the preprocessor to remove the comma before it. If you do provide some variable arguments in your macro invocation, GNU CPP does not complain about the paste operation and instead places the variable arguments after the comma. Just like any other pasted macro argument, these arguments are not macro expanded.
Recently, the preprocessor has relaxed its treatment of escaped newlines. Previously, the newline had to immediately follow a backslash. The current implementation allows whitespace in the form of spaces, horizontal and vertical tabs, and form feeds between the backslash and the subsequent newline. The preprocessor issues a warning, but treats it as a valid escaped newline and combines the two lines to form a single logical line. This works within comments and tokens, as well as between tokens. Comments are not treated as whitespace for the purposes of this relaxation, since they have not yet been replaced with spaces.
In ISO C99, arrays that are not lvalues still decay to pointers, and may be subscripted, although they may not be modified or used after the next sequence point and the unary ‘&’ operator may not be applied to them. As an extension, GCC allows such arrays to be subscripted in C90 mode, though otherwise they do not decay to pointers outside C99 mode. For example, this is valid in GNU C though not valid in C90:
struct foo {int a[4];};
struct foo f();
bar (int index)
{
return f().a[index];
}
void- and Function-Pointers
In GNU C, addition and subtraction operations are supported on pointers to
void and on pointers to functions. This is done by treating the
size of a void or of a function as 1.
A consequence of this is that sizeof is also allowed on void
and on function types, and returns 1.
The option -Wpointer-arith requests a warning if these extensions are used.
As in standard C++ and ISO C99, the elements of an aggregate initializer for an automatic variable are not required to be constant expressions in GNU C. Here is an example of an initializer with run-time varying elements:
foo (float f, float g)
{
float beat_freqs[2] = { f-g, f+g };
/* ... */
}
ISO C99 supports compound literals. A compound literal looks like a cast containing an initializer. Its value is an object of the type specified in the cast, containing the elements specified in the initializer; it is an lvalue. As an extension, GCC supports compound literals in C90 mode and in C++, though the semantics are somewhat different in C++.
Usually, the specified type is a structure. Assume that
struct foo and structure are declared as shown:
struct foo {int a; char b[2];} structure;
Here is an example of constructing a struct foo with a compound literal:
structure = ((struct foo) {x + y, 'a', 0});
This is equivalent to writing the following:
{
struct foo temp = {x + y, 'a', 0};
structure = temp;
}
You can also construct an array, though this is dangerous in C++, as explained below. If all the elements of the compound literal are (made up of) simple constant expressions, suitable for use in initializers of objects of static storage duration, then the compound literal can be coerced to a pointer to its first element and used in such an initializer, as shown here:
char **foo = (char *[]) { "x", "y", "z" };
Compound literals for scalar types and union types are also allowed, but then the compound literal is equivalent to a cast.
As a GNU extension, GCC allows initialization of objects with static storage duration by compound literals (which is not possible in ISO C99, because the initializer is not a constant). It is handled as if the object was initialized only with the bracket enclosed list if the types of the compound literal and the object match. The initializer list of the compound literal must be constant. If the object being initialized has array type of unknown size, the size is determined by compound literal size.
static struct foo x = (struct foo) {1, 'a', 'b'};
static int y[] = (int []) {1, 2, 3};
static int z[] = (int [3]) {1};
The above lines are equivalent to the following:
static struct foo x = {1, 'a', 'b'};
static int y[] = {1, 2, 3};
static int z[] = {1, 0, 0};
In C, a compound literal designates an unnamed object with static or automatic storage duration. In C++, a compound literal designates a temporary object, which only lives until the end of its full-expression. As a result, well-defined C code that takes the address of a subobject of a compound literal can be undefined in C++. For instance, if the array compound literal example above appeared inside a function, any subsequent use of ‘foo’ in C++ has undefined behavior because the lifetime of the array ends after the declaration of ‘foo’. As a result, the C++ compiler now rejects the conversion of a temporary array to a pointer.
As an optimization, the C++ compiler sometimes gives array compound literals longer lifetimes: when the array either appears outside a function or has const-qualified type. If ‘foo’ and its initializer had elements of ‘char *const’ type rather than ‘char *’, or if ‘foo’ were a global variable, the array would have static storage duration. But it is probably safest just to avoid the use of array compound literals in code compiled as C++.
Standard C90 requires the elements of an initializer to appear in a fixed order, the same as the order of the elements in the array or structure being initialized.
In ISO C99 you can give the elements in any order, specifying the array indices or structure field names they apply to, and GNU C allows this as an extension in C90 mode as well. This extension is not implemented in GNU C++.
To specify an array index, write ‘[index] =’ before the element value. For example,
int a[6] = { [4] = 29, [2] = 15 };
is equivalent to
int a[6] = { 0, 0, 15, 0, 29, 0 };
The index values must be constant expressions, even if the array being initialized is automatic.
An alternative syntax for this which has been obsolete since GCC 2.5 but GCC still accepts is to write ‘[index]’ before the element value, with no ‘=’.
To initialize a range of elements to the same value, write ‘[first ... last] = value’. This is a GNU extension. For example,
int widths[] = { [0 ... 9] = 1, [10 ... 99] = 2, [100] = 3 };
If the value in it has side-effects, the side-effects will happen only once, not for each initialized field by the range initializer.
Note that the length of the array is the highest value specified plus one.
In a structure initializer, specify the name of a field to initialize with ‘.fieldname =’ before the element value. For example, given the following structure,
struct point { int x, y; };
the following initialization
struct point p = { .y = yvalue, .x = xvalue };
is equivalent to
struct point p = { xvalue, yvalue };
Another syntax which has the same meaning, obsolete since GCC 2.5, is ‘fieldname:’, as shown here:
struct point p = { y: yvalue, x: xvalue };
The ‘[index]’ or ‘.fieldname’ is known as a designator. You can also use a designator (or the obsolete colon syntax) when initializing a union, to specify which element of the union should be used. For example,
union foo { int i; double d; };
union foo f = { .d = 4 };
will convert 4 to a double to store it in the union using
the second element. By contrast, casting 4 to type union foo
would store it into the union as the integer i, since it is
an integer. (See Cast to Union.)
You can combine this technique of naming elements with ordinary C initialization of successive elements. Each initializer element that does not have a designator applies to the next consecutive element of the array or structure. For example,
int a[6] = { [1] = v1, v2, [4] = v4 };
is equivalent to
int a[6] = { 0, v1, v2, 0, v4, 0 };
Labeling the elements of an array initializer is especially useful
when the indices are characters or belong to an enum type.
For example:
int whitespace[256]
= { [' '] = 1, ['\t'] = 1, ['\h'] = 1,
['\f'] = 1, ['\n'] = 1, ['\r'] = 1 };
You can also write a series of ‘.fieldname’ and ‘[index]’ designators before an ‘=’ to specify a nested subobject to initialize; the list is taken relative to the subobject corresponding to the closest surrounding brace pair. For example, with the ‘struct point’ declaration above:
struct point ptarray[10] = { [2].y = yv2, [2].x = xv2, [0].x = xv0 };
If the same field is initialized multiple times, it will have value from the last initialization. If any such overridden initialization has side-effect, it is unspecified whether the side-effect happens or not. Currently, GCC will discard them and issue a warning.
You can specify a range of consecutive values in a single case label,
like this:
case low ... high:
This has the same effect as the proper number of individual case
labels, one for each integer value from low to high, inclusive.
This feature is especially useful for ranges of ASCII character codes:
case 'A' ... 'Z':
Be careful: Write spaces around the ..., for otherwise
it may be parsed wrong when you use it with integer values. For example,
write this:
case 1 ... 5:
rather than this:
case 1...5:
A cast to union type is similar to other casts, except that the type
specified is a union type. You can specify the type either with
union tag or with a typedef name. A cast to union is actually
a constructor though, not a cast, and hence does not yield an lvalue like
normal casts. (See Compound Literals.)
The types that may be cast to the union type are those of the members of the union. Thus, given the following union and variables:
union foo { int i; double d; };
int x;
double y;
both x and y can be cast to type union foo.
Using the cast as the right-hand side of an assignment to a variable of union type is equivalent to storing in a member of the union:
union foo u;
/* ... */
u = (union foo) x == u.i = x
u = (union foo) y == u.d = y
You can also use the union cast as a function argument:
void hack (union foo);
/* ... */
hack ((union foo) x);
ISO C99 and ISO C++ allow declarations and code to be freely mixed within compound statements. As an extension, GCC also allows this in C90 mode. For example, you could do:
int i;
/* ... */
i++;
int j = i + 2;
Each identifier is visible from where it is declared until the end of the enclosing block.
In GNU C, you declare certain things about functions called in your program which help the compiler optimize function calls and check your code more carefully.
The keyword __attribute__ allows you to specify special
attributes when making a declaration. This keyword is followed by an
attribute specification inside double parentheses. The following
attributes are currently defined for functions on all targets:
aligned, alloc_size, noreturn,
returns_twice, noinline, noclone,
always_inline, flatten, pure, const,
nothrow, sentinel, format, format_arg,
no_instrument_function, no_split_stack,
section, constructor,
destructor, used, unused, deprecated,
weak, malloc, alias, ifunc,
warn_unused_result, nonnull, gnu_inline,
externally_visible, hot, cold, artificial,
error and warning. Several other attributes are defined
for functions on particular target systems. Other attributes,
including section are supported for variables declarations
(see Variable Attributes) and for types (see Type Attributes).
GCC plugins may provide their own attributes.
You may also specify attributes with ‘__’ preceding and following
each keyword. This allows you to use them in header files without
being concerned about a possible macro of the same name. For example,
you may use __noreturn__ instead of noreturn.
See Attribute Syntax, for details of the exact syntax for using attributes.
alias ("target")alias attribute causes the declaration to be emitted as an
alias for another symbol, which must be specified. For instance,
void __f () { /* Do something. */; }
void f () __attribute__ ((weak, alias ("__f")));
defines ‘f’ to be a weak alias for ‘__f’. In C++, the mangled name for the target must be used. It is an error if ‘__f’ is not defined in the same translation unit.
Not all target machines support this attribute.
aligned (alignment)You cannot use this attribute to decrease the alignment of a function, only to increase it. However, when you explicitly specify a function alignment this will override the effect of the -falign-functions (see Optimize Options) option for this function.
Note that the effectiveness of aligned attributes may be
limited by inherent limitations in your linker. On many systems, the
linker is only able to arrange for functions to be aligned up to a
certain maximum alignment. (For some linkers, the maximum supported
alignment may be very very small.) See your linker documentation for
further information.
The aligned attribute can also be used for variables and fields
(see Variable Attributes.)
alloc_sizealloc_size attribute is used to tell the compiler that the
function return value points to memory, where the size is given by
one or two of the functions parameters. GCC uses this
information to improve the correctness of __builtin_object_size.
The function parameter(s) denoting the allocated size are specified by one or two integer arguments supplied to the attribute. The allocated size is either the value of the single function argument specified or the product of the two function arguments specified. Argument numbering starts at one.
For instance,
void* my_calloc(size_t, size_t) __attribute__((alloc_size(1,2)))
void my_realloc(void*, size_t) __attribute__((alloc_size(2)))
declares that my_calloc will return memory of the size given by
the product of parameter 1 and 2 and that my_realloc will return memory
of the size given by parameter 2.
always_inlinegnu_inlineinline keyword. It directs GCC to treat the function
as if it were defined in gnu90 mode even when compiling in C99 or
gnu99 mode.
If the function is declared extern, then this definition of the
function is used only for inlining. In no case is the function
compiled as a standalone function, not even if you take its address
explicitly. Such an address becomes an external reference, as if you
had only declared the function, and had not defined it. This has
almost the effect of a macro. The way to use this is to put a
function definition in a header file with this attribute, and put
another copy of the function, without extern, in a library
file. The definition in the header file will cause most calls to the
function to be inlined. If any uses of the function remain, they will
refer to the single copy in the library. Note that the two
definitions of the functions need not be precisely the same, although
if they do not have the same effect your program may behave oddly.
In C, if the function is neither extern nor static, then
the function is compiled as a standalone function, as well as being
inlined where possible.
This is how GCC traditionally handled functions declared
inline. Since ISO C99 specifies a different semantics for
inline, this function attribute is provided as a transition
measure and as a useful feature in its own right. This attribute is
available in GCC 4.1.3 and later. It is available if either of the
preprocessor macros __GNUC_GNU_INLINE__ or
__GNUC_STDC_INLINE__ are defined. See An Inline Function is As Fast As a Macro.
In C++, this attribute does not depend on extern in any way,
but it still requires the inline keyword to enable its special
behavior.
artificialbank_switchflattenerror ("message")__builtin_constant_p
and inline functions where checking the inline function arguments is not
possible through extern char [(condition) ? 1 : -1]; tricks.
While it is possible to leave the function undefined and thus invoke
a link failure, when using this attribute the problem will be diagnosed
earlier and with exact location of the call even in presence of inline
functions or when not emitting debugging information.
warning ("message")__builtin_constant_p
and inline functions. While it is possible to define the function with
a message in .gnu.warning* section, when using this attribute the problem
will be diagnosed earlier and with exact location of the call even in presence
of inline functions or when not emitting debugging information.
cdeclcdecl attribute causes the compiler to
assume that the calling function will pop off the stack space used to
pass arguments. This is
useful to override the effects of the -mrtd switch.
constpure attribute below, since function is not
allowed to read global memory.
Note that a function that has pointer arguments and examines the data
pointed to must not be declared const. Likewise, a
function that calls a non-const function usually must not be
const. It does not make sense for a const function to
return void.
The attribute const is not implemented in GCC versions earlier
than 2.5. An alternative way to declare that a function has no side
effects, which works in the current version and in some older versions,
is as follows:
typedef int intfn ();
extern const intfn square;
This approach does not work in GNU C++ from 2.6.0 on, since the language
specifies that the ‘const’ must be attached to the return value.
constructordestructorconstructor (priority)destructor (priority)constructor attribute causes the function to be called
automatically before execution enters main (). Similarly, the
destructor attribute causes the function to be called
automatically after main () has completed or exit () has
been called. Functions with these attributes are useful for
initializing data that will be used implicitly during the execution of
the program.
You may provide an optional integer priority to control the order in which constructor and destructor functions are run. A constructor with a smaller priority number runs before a constructor with a larger priority number; the opposite relationship holds for destructors. So, if you have a constructor that allocates a resource and a destructor that deallocates the same resource, both functions typically have the same priority. The priorities for constructor and destructor functions are the same as those specified for namespace-scope C++ objects (see C++ Attributes).
These attributes are not currently implemented for Objective-C.
deprecateddeprecated (msg)deprecated attribute results in a warning if the function
is used anywhere in the source file. This is useful when identifying
functions that are expected to be removed in a future version of a
program. The warning also includes the location of the declaration
of the deprecated function, to enable users to easily find further
information about why the function is deprecated, or what they should
do instead. Note that the warnings only occurs for uses:
int old_fn () __attribute__ ((deprecated));
int old_fn ();
int (*fn_ptr)() = old_fn;
results in a warning on line 3 but not line 2. The optional msg argument, which must be a string, will be printed in the warning if present.
The deprecated attribute can also be used for variables and
types (see Variable Attributes, see Type Attributes.)
disinterruptdllexportdllexport attribute causes the compiler to provide a global
pointer to a pointer in a DLL, so that it can be referenced with the
dllimport attribute. On Microsoft Windows targets, the pointer
name is formed by combining _imp__ and the function or variable
name.
You can use __declspec(dllexport) as a synonym for
__attribute__ ((dllexport)) for compatibility with other
compilers.
On systems that support the visibility attribute, this
attribute also implies “default” visibility. It is an error to
explicitly specify any other visibility.
In previous versions of GCC, the dllexport attribute was ignored
for inlined functions, unless the -fkeep-inline-functions flag
had been used. The default behaviour now is to emit all dllexported
inline functions; however, this can cause object file-size bloat, in
which case the old behaviour can be restored by using
-fno-keep-inline-dllexport.
The attribute is also ignored for undefined symbols.
When applied to C++ classes, the attribute marks defined non-inlined member functions and static data members as exports. Static consts initialized in-class are not marked unless they are also defined out-of-class.
For Microsoft Windows targets there are alternative methods for
including the symbol in the DLL's export table such as using a
.def file with an EXPORTS section or, with GNU ld, using
the --export-all linker flag.
dllimportdllimport
attribute causes the compiler to reference a function or variable via
a global pointer to a pointer that is set up by the DLL exporting the
symbol. The attribute implies extern. On Microsoft Windows
targets, the pointer name is formed by combining _imp__ and the
function or variable name.
You can use __declspec(dllimport) as a synonym for
__attribute__ ((dllimport)) for compatibility with other
compilers.
On systems that support the visibility attribute, this
attribute also implies “default” visibility. It is an error to
explicitly specify any other visibility.
Currently, the attribute is ignored for inlined functions. If the
attribute is applied to a symbol definition, an error is reported.
If a symbol previously declared dllimport is later defined, the
attribute is ignored in subsequent references, and a warning is emitted.
The attribute is also overridden by a subsequent declaration as
dllexport.
When applied to C++ classes, the attribute marks non-inlined member functions and static data members as imports. However, the attribute is ignored for virtual methods to allow creation of vtables using thunks.
On the SH Symbian OS target the dllimport attribute also has
another affect—it can cause the vtable and run-time type information
for a class to be exported. This happens when the class has a
dllimport'ed constructor or a non-inline, non-pure virtual function
and, for either of those two conditions, the class also has an inline
constructor or destructor and has a key function that is defined in
the current translation unit.
For Microsoft Windows based targets the use of the dllimport
attribute on functions is not necessary, but provides a small
performance benefit by eliminating a thunk in the DLL. The use of the
dllimport attribute on imported variables was required on older
versions of the GNU linker, but can now be avoided by passing the
--enable-auto-import switch to the GNU linker. As with
functions, using the attribute for a variable eliminates a thunk in
the DLL.
One drawback to using this attribute is that a pointer to a
variable marked as dllimport cannot be used as a constant
address. However, a pointer to a function with the
dllimport attribute can be used as a constant initializer; in
this case, the address of a stub function in the import lib is
referenced. On Microsoft Windows targets, the attribute can be disabled
for functions by setting the -mnop-fun-dllimport flag.
eightbit_dataYou must use GAS and GLD from GNU binutils version 2.7 or later for
this attribute to work correctly.
exception_handlerexternally_visibleexternally_visible attributes are automatically added to functions (not variable yet due to a current gold issue) that are accessed outside of LTO objects according to resolution file produced by gold. For other linkers that cannot generate resolution file, explicit externally_visible attributes are still necessary.
farfar attribute causes the compiler to
use a calling convention that takes care of switching memory banks when
entering and leaving a function. This calling convention is also the
default when using the -mlong-calls option.
On 68HC12 the compiler will use the call and rtc instructions
to call and return from a function.
On 68HC11 the compiler will generate a sequence of instructions
to invoke a board-specific routine to switch the memory bank and call the
real function. The board-specific routine simulates a call.
At the end of a function, it will jump to a board-specific routine
instead of using rts. The board-specific return routine simulates
the rtc.
On MeP targets this causes the compiler to use a calling convention
which assumes the called function is too far away for the built-in
addressing modes.
fast_interruptinterrupt attribute, except that freit is used to return
instead of reit.
fastcallfastcall attribute causes the compiler to
pass the first argument (if of integral type) in the register ECX and
the second argument (if of integral type) in the register EDX. Subsequent
and other typed arguments are passed on the stack. The called function will
pop the arguments off the stack. If the number of arguments is variable all
arguments are pushed on the stack.
thiscallthiscall attribute causes the compiler to
pass the first argument (if of integral type) in the register ECX.
Subsequent and other typed arguments are passed on the stack. The called
function will pop the arguments off the stack.
If the number of arguments is variable all arguments are pushed on the
stack.
The thiscall attribute is intended for C++ non-static member functions.
As gcc extension this calling convention can be used for C-functions
and for static member methods.
format (archetype, string-index, first-to-check)format attribute specifies that a function takes printf,
scanf, strftime or strfmon style arguments which
should be type-checked against a format string. For example, the
declaration:
extern int
my_printf (void *my_object, const char *my_format, ...)
__attribute__ ((format (printf, 2, 3)));
causes the compiler to check the arguments in calls to my_printf
for consistency with the printf style format string argument
my_format.
The parameter archetype determines how the format string is
interpreted, and should be printf, scanf, strftime,
gnu_printf, gnu_scanf, gnu_strftime or
strfmon. (You can also use __printf__,
__scanf__, __strftime__ or __strfmon__.) On
MinGW targets, ms_printf, ms_scanf, and
ms_strftime are also present.
archtype values such as printf refer to the formats accepted
by the system's C run-time library, while gnu_ values always refer
to the formats accepted by the GNU C Library. On Microsoft Windows
targets, ms_ values refer to the formats accepted by the
msvcrt.dll library.
The parameter string-index
specifies which argument is the format string argument (starting
from 1), while first-to-check is the number of the first
argument to check against the format string. For functions
where the arguments are not available to be checked (such as
vprintf), specify the third parameter as zero. In this case the
compiler only checks the format string for consistency. For
strftime formats, the third parameter is required to be zero.
Since non-static C++ methods have an implicit this argument, the
arguments of such methods should be counted from two, not one, when
giving values for string-index and first-to-check.
In the example above, the format string (my_format) is the second
argument of the function my_print, and the arguments to check
start with the third argument, so the correct parameters for the format
attribute are 2 and 3.
The format attribute allows you to identify your own functions
which take format strings as arguments, so that GCC can check the
calls to these functions for errors. The compiler always (unless
-ffreestanding or -fno-builtin is used) checks formats
for the standard library functions printf, fprintf,
sprintf, scanf, fscanf, sscanf, strftime,
vprintf, vfprintf and vsprintf whenever such
warnings are requested (using -Wformat), so there is no need to
modify the header file stdio.h. In C99 mode, the functions
snprintf, vsnprintf, vscanf, vfscanf and
vsscanf are also checked. Except in strictly conforming C
standard modes, the X/Open function strfmon is also checked as
are printf_unlocked and fprintf_unlocked.
See Options Controlling C Dialect.
For Objective-C dialects, NSString (or __NSString__) is
recognized in the same context. Declarations including these format attributes
will be parsed for correct syntax, however the result of checking of such format
strings is not yet defined, and will not be carried out by this version of the
compiler.
The target may also provide additional types of format checks.
See Format Checks Specific to Particular Target Machines.
format_arg (string-index)format_arg attribute specifies that a function takes a format
string for a printf, scanf, strftime or
strfmon style function and modifies it (for example, to translate
it into another language), so the result can be passed to a
printf, scanf, strftime or strfmon style
function (with the remaining arguments to the format function the same
as they would have been for the unmodified string). For example, the
declaration:
extern char *
my_dgettext (char *my_domain, const char *my_format)
__attribute__ ((format_arg (2)));
causes the compiler to check the arguments in calls to a printf,
scanf, strftime or strfmon type function, whose
format string argument is a call to the my_dgettext function, for
consistency with the format string argument my_format. If the
format_arg attribute had not been specified, all the compiler
could tell in such calls to format functions would be that the format
string argument is not constant; this would generate a warning when
-Wformat-nonliteral is used, but the calls could not be checked
without the attribute.
The parameter string-index specifies which argument is the format
string argument (starting from one). Since non-static C++ methods have
an implicit this argument, the arguments of such methods should
be counted from two.
The format-arg attribute allows you to identify your own
functions which modify format strings, so that GCC can check the
calls to printf, scanf, strftime or strfmon
type function whose operands are a call to one of your own function.
The compiler always treats gettext, dgettext, and
dcgettext in this manner except when strict ISO C support is
requested by -ansi or an appropriate -std option, or
-ffreestanding or -fno-builtin
is used. See Options Controlling C Dialect.
For Objective-C dialects, the format-arg attribute may refer to an
NSString reference for compatibility with the format attribute
above.
The target may also allow additional types in format-arg attributes.
See Format Checks Specific to Particular Target Machines.
function_vectorIn SH2A target, this attribute declares a function to be called using the TBR relative addressing mode. The argument to this attribute is the entry number of the same function in a vector table containing all the TBR relative addressable functions. For the successful jump, register TBR should contain the start address of this TBR relative vector table. In the startup routine of the user application, user needs to care of this TBR register initialization. The TBR relative vector table can have at max 256 function entries. The jumps to these functions will be generated using a SH2A specific, non delayed branch instruction JSR/N @(disp8,TBR). You must use GAS and GLD from GNU binutils version 2.7 or later for this attribute to work correctly.
Please refer the example of M16C target, to see the use of this attribute while declaring a function,
In an application, for a function being called once, this attribute will save at least 8 bytes of code; and if other successive calls are being made to the same function, it will save 2 bytes of code per each of these calls.
On M16C/M32C targets, the function_vector attribute declares a
special page subroutine call function. Use of this attribute reduces
the code size by 2 bytes for each call generated to the
subroutine. The argument to the attribute is the vector number entry
from the special page vector table which contains the 16 low-order
bits of the subroutine's entry address. Each vector table has special
page number (18 to 255) which are used in jsrs instruction.
Jump addresses of the routines are generated by adding 0x0F0000 (in
case of M16C targets) or 0xFF0000 (in case of M32C targets), to the 2
byte addresses set in the vector table. Therefore you need to ensure
that all the special page vector routines should get mapped within the
address range 0x0F0000 to 0x0FFFFF (for M16C) and 0xFF0000 to 0xFFFFFF
(for M32C).
In the following example 2 bytes will be saved for each call to
function foo.
void foo (void) __attribute__((function_vector(0x18)));
void foo (void)
{
}
void bar (void)
{
foo();
}
If functions are defined in one file and are called in another file, then be sure to write this declaration in both files.
This attribute is ignored for R8C target.
ifunc ("resolver")ifunc attribute is used to mark a function as an indirect
function using the STT_GNU_IFUNC symbol type extension to the ELF
standard. This allows the resolution of the symbol value to be
determined dynamically at load time, and an optimized version of the
routine can be selected for the particular processor or other system
characteristics determined then. To use this attribute, first define
the implementation functions available, and a resolver function that
returns a pointer to the selected implementation function. The
implementation functions' declarations must match the API of the
function being implemented, the resolver's declaration is be a
function returning pointer to void function returning void:
void *my_memcpy (void *dst, const void *src, size_t len)
{
...
}
static void (*resolve_memcpy (void)) (void)
{
return my_memcpy; // we'll just always select this routine
}
The exported header file declaring the function the user calls would contain:
extern void *memcpy (void *, const void *, size_t);
allowing the user to call this as a regular function, unaware of the implementation. Finally, the indirect function needs to be defined in the same translation unit as the resolver function:
void *memcpy (void *, const void *, size_t)
__attribute__ ((ifunc ("resolve_memcpy")));
Indirect functions cannot be weak, and require a recent binutils (at
least version 2.20.1), and GNU C library (at least version 2.11.1).
interruptNote, interrupt handlers for the Blackfin, H8/300, H8/300H, H8S, MicroBlaze,
and SH processors can be specified via the interrupt_handler attribute.
Note, on the AVR, the hardware globally disables interrupts when an
interrupt is executed. The first instruction of an interrupt handler
declared with this attribute will be a SEI instruction to
re-enable interrupts. See also the signal function attribute
that does not insert a SEI instuction. If both signal and
interrupt are specified for the same function, signal
will be silently ignored.
Note, for the ARM, you can specify the kind of interrupt to be handled by adding an optional parameter to the interrupt attribute like this:
void f () __attribute__ ((interrupt ("IRQ")));
Permissible values for this parameter are: IRQ, FIQ, SWI, ABORT and UNDEF.
On ARMv7-M the interrupt type is ignored, and the attribute means the function may be called with a word aligned stack pointer.
On Epiphany targets one or more optional parameters can be added like this:
void __attribute__ ((interrupt ("dma0, dma1"))) universal_dma_handler ();
Permissible values for these parameters are: reset,
software_exception, page_miss,
timer0, timer1, message,
dma0, dma1, wand and swi.
Multiple parameters indicate that multiple entries in the interrupt
vector table should be initialized for this function, i.e. for each
parameter name, a jump to the function will be emitted in
the section ivt_entry_name. The parameter(s) may be omitted
entirely, in which case no interrupt vector table entry will be provided.
Note, on Epiphany targets, interrupts are enabled inside the function
unless the disinterrupt attribute is also specified.
On Epiphany targets, you can also use the following attribute to modify the behavior of an interrupt handler:
forwarder_sectionThe following examples are all valid uses of these attributes on Epiphany targets:
void __attribute__ ((interrupt)) universal_handler ();
void __attribute__ ((interrupt ("dma1"))) dma1_handler ();
void __attribute__ ((interrupt ("dma0, dma1"))) universal_dma_handler ();
void __attribute__ ((interrupt ("timer0"), disinterrupt))
fast_timer_handler ();
void __attribute__ ((interrupt ("dma0, dma1"), forwarder_section ("tramp")))
external_dma_handler ();
On MIPS targets, you can use the following attributes to modify the behavior of an interrupt handler:
use_shadow_register_setkeep_interrupts_maskeduse_debug_exception_returnderet instruction. Interrupt handlers that don't
have this attribute return using eret instead.
You can use any combination of these attributes, as shown below:
void __attribute__ ((interrupt)) v0 ();
void __attribute__ ((interrupt, use_shadow_register_set)) v1 ();
void __attribute__ ((interrupt, keep_interrupts_masked)) v2 ();
void __attribute__ ((interrupt, use_debug_exception_return)) v3 ();
void __attribute__ ((interrupt, use_shadow_register_set,
keep_interrupts_masked)) v4 ();
void __attribute__ ((interrupt, use_shadow_register_set,
use_debug_exception_return)) v5 ();
void __attribute__ ((interrupt, keep_interrupts_masked,
use_debug_exception_return)) v6 ();
void __attribute__ ((interrupt, use_shadow_register_set,
keep_interrupts_masked,
use_debug_exception_return)) v7 ();
On RL78, use brk_interrupt instead of interrupt for
handlers intended to be used with the BRK opcode (i.e. those
that must end with RETB instead of RETI).
interrupt_handlerinterrupt_threadsleep
instruction. This attribute is available only on fido.
isrinterrupt attribute above.
kspisuspinterrupt_handler, exception_handler
or nmi_handler, code will be generated to load the stack pointer
from the USP register in the function prologue.
l1_text.l1.text.
With -mfdpic, function calls with a such function as the callee
or caller will use inlined PLT.
l2.l1.text. With -mfdpic, callers of such functions will use
an inlined PLT.
leafThe attribute is intended for library functions to improve dataflow analysis.
The compiler takes the hint that any data not escaping the current compilation unit can
not be used or modified by the leaf function. For example, the sin function
is a leaf function, but qsort is not.
Note that leaf functions might invoke signals and signal handlers might be
defined in the current compilation unit and use static variables. The only
compliant way to write such a signal handler is to declare such variables
volatile.
The attribute has no effect on functions defined within the current compilation
unit. This is to allow easy merging of multiple compilation units into one,
for example, by using the link time optimization. For this reason the
attribute is not allowed on types to annotate indirect calls.
long_call/short_call#pragma long_calls settings. The
long_call attribute indicates that the function might be far
away from the call site and require a different (more expensive)
calling sequence. The short_call attribute always places
the offset to the function from the call site into the ‘BL’
instruction directly.
longcall/shortcalllongcall attribute
indicates that the function might be far away from the call site and
require a different (more expensive) calling sequence. The
shortcall attribute indicates that the function is always close
enough for the shorter calling sequence to be used. These attributes
override both the -mlongcall switch and, on the RS/6000 and
PowerPC, the #pragma longcall setting.
See RS/6000 and PowerPC Options, for more information on whether long
calls are necessary.
long_call/near/farlong_call and far attributes are
synonyms, and cause the compiler to always call
the function by first loading its address into a register, and then using
the contents of that register. The near attribute has the opposite
effect; it specifies that non-PIC calls should be made using the more
efficient jal instruction.
mallocmalloc attribute is used to tell the compiler that a function
may be treated as if any non-NULL pointer it returns cannot
alias any other pointer valid when the function returns and that the memory
has undefined content.
This will often improve optimization.
Standard functions with this property include malloc and
calloc. realloc-like functions do not have this
property as the memory pointed to does not have undefined content.
mips16/nomips16mips16 and nomips16
function attributes to locally select or turn off MIPS16 code generation.
A function with the mips16 attribute is emitted as MIPS16 code,
while MIPS16 code generation is disabled for functions with the
nomips16 attribute. These attributes override the
-mips16 and -mno-mips16 options on the command line
(see MIPS Options).
When compiling files containing mixed MIPS16 and non-MIPS16 code, the
preprocessor symbol __mips16 reflects the setting on the command line,
not that within individual functions. Mixed MIPS16 and non-MIPS16 code
may interact badly with some GCC extensions such as __builtin_apply
(see Constructing Calls).
model (model-name)small, medium, or
large, representing each of the code models.
Small model objects live in the lower 16MB of memory (so that their
addresses can be loaded with the ld24 instruction), and are
callable with the bl instruction.
Medium model objects may live anywhere in the 32-bit address space (the
compiler will generate seth/add3 instructions to load their addresses),
and are callable with the bl instruction.
Large model objects may live anywhere in the 32-bit address space (the
compiler will generate seth/add3 instructions to load their addresses),
and may not be reachable with the bl instruction (the compiler will
generate the much slower seth/add3/jl instruction sequence).
On IA-64, use this attribute to set the addressability of an object.
At present, the only supported identifier for model-name is
small, indicating addressability via “small” (22-bit)
addresses (so that their addresses can be loaded with the addl
instruction). Caveat: such addressing is by definition not position
independent and hence this attribute must not be used for objects
defined by shared libraries.
ms_abi/sysv_abims_abi attribute tells the compiler to use the Microsoft ABI,
while the sysv_abi attribute tells the compiler to use the ABI
used on GNU/Linux and other systems. The default is to use the Microsoft ABI
when targeting Windows. On all other systems, the default is the x86/AMD ABI.
Note, the ms_abi attribute for Windows 64-bit targets currently
requires the -maccumulate-outgoing-args option.
callee_pop_aggregate_return (number)Note, that on 32-bit i386 Windows targets the compiler assumes that the
caller pops the stack for hidden pointer.
ms_hook_prologuenakedasm statements that do not have operands. All other statements,
including declarations of local variables, if statements, and so
forth, should be avoided. Naked functions should be used to implement the
body of an assembly function, while allowing the compiler to construct
the requisite function declaration for the assembler.
nearnear attribute causes the compiler to
use the normal calling convention based on jsr and rts.
This attribute can be used to cancel the effect of the -mlong-calls
option.
On MeP targets this attribute causes the compiler to assume the called
function is close enough to use the normal calling convention,
overriding the -mtf command line option.
nestinginterrupt_handler,
exception_handler or nmi_handler to indicate that the function
entry code should enable nested interrupts or exceptions.
nmi_handlerno_instrument_functionno_split_stackno_split_stack attribute will not have that prologue, and thus
may run with only a small amount of stack space available.
noinline asm ("");
(see Extended Asm) in the called function, to serve as a special
side-effect.
noclonenonnull (arg-index, ...)nonnull attribute specifies that some function parameters should
be non-null pointers. For instance, the declaration:
extern void *
my_memcpy (void *dest, const void *src, size_t len)
__attribute__((nonnull (1, 2)));
causes the compiler to check that, in calls to my_memcpy,
arguments dest and src are non-null. If the compiler
determines that a null pointer is passed in an argument slot marked
as non-null, and the -Wnonnull option is enabled, a warning
is issued. The compiler may also choose to make optimizations based
on the knowledge that certain function arguments will not be null.
If no argument index list is given to the nonnull attribute,
all pointer arguments are marked as non-null. To illustrate, the
following declaration is equivalent to the previous example:
extern void *
my_memcpy (void *dest, const void *src, size_t len)
__attribute__((nonnull));
noreturnabort and exit,
cannot return. GCC knows this automatically. Some programs define
their own functions that never return. You can declare them
noreturn to tell the compiler this fact. For example,
void fatal () __attribute__ ((noreturn));
void
fatal (/* ... */)
{
/* ... */ /* Print error message. */ /* ... */
exit (1);
}
The noreturn keyword tells the compiler to assume that
fatal cannot return. It can then optimize without regard to what
would happen if fatal ever did return. This makes slightly
better code. More importantly, it helps avoid spurious warnings of
uninitialized variables.
The noreturn keyword does not affect the exceptional path when that
applies: a noreturn-marked function may still return to the caller
by throwing an exception or calling longjmp.
Do not assume that registers saved by the calling function are
restored before calling the noreturn function.
It does not make sense for a noreturn function to have a return
type other than void.
The attribute noreturn is not implemented in GCC versions
earlier than 2.5. An alternative way to declare that a function does
not return, which works in the current version and in some older
versions, is as follows:
typedef void voidfn ();
volatile voidfn fatal;
This approach does not work in GNU C++.
nothrownothrow attribute is used to inform the compiler that a
function cannot throw an exception. For example, most functions in
the standard C library can be guaranteed not to throw an exception
with the notable exceptions of qsort and bsearch that
take function pointer arguments. The nothrow attribute is not
implemented in GCC versions earlier than 3.3.
optimizeoptimize attribute is used to specify that a function is to
be compiled with different optimization options than specified on the
command line. Arguments can either be numbers or strings. Numbers
are assumed to be an optimization level. Strings that begin with
O are assumed to be an optimization option, while other options
are assumed to be used with a -f prefix. You can also use the
‘#pragma GCC optimize’ pragma to set the optimization options
that affect more than one function.
See Function Specific Option Pragmas, for details about the
‘#pragma GCC optimize’ pragma.
This can be used for instance to have frequently executed functions
compiled with more aggressive optimization options that produce faster
and larger code, while other functions can be called with less
aggressive options.
OS_main/OS_taskOS_main or OS_task attribute
do not save/restore any call-saved register in their prologue/epilogue.
The OS_main attribute can be used when there is
guarantee that interrupts are disabled at the time when the function
is entered. This will save resources when the stack pointer has to be
changed to set up a frame for local variables.
The OS_task attribute can be used when there is no
guarantee that interrupts are disabled at that time when the function
is entered like for, e.g. task functions in a multi-threading operating
system. In that case, changing the stack pointer register will be
guarded by save/clear/restore of the global interrupt enable flag.
The differences to the naked function attribute are:
naked functions do not have a return instruction whereas
OS_main and OS_task functions will have a RET or
RETI return instruction.
naked functions do not set up a frame for local variables
or a frame pointer whereas OS_main and OS_task do this
as needed.
pcspcs attribute can be used to control the calling convention
used for a function on ARM. The attribute takes an argument that specifies
the calling convention to use.
When compiling using the AAPCS ABI (or a variant of that) then valid
values for the argument are "aapcs" and "aapcs-vfp". In
order to use a variant other than "aapcs" then the compiler must
be permitted to use the appropriate co-processor registers (i.e., the
VFP registers must be available in order to use "aapcs-vfp").
For example,
/* Argument passed in r0, and result returned in r0+r1. */
double f2d (float) __attribute__((pcs("aapcs")));
Variadic functions always use the "aapcs" calling convention and
the compiler will reject attempts to specify an alternative.
purepure. For example,
int square (int) __attribute__ ((pure));
says that the hypothetical function square is safe to call
fewer times than the program says.
Some of common examples of pure functions are strlen or memcmp.
Interesting non-pure functions are functions with infinite loops or those
depending on volatile memory or other system resource, that may change between
two consecutive calls (such as feof in a multithreading environment).
The attribute pure is not implemented in GCC versions earlier
than 2.96.
hothot attribute is used to inform the compiler that a function is a
hot spot of the compiled program. The function is optimized more aggressively
and on many target it is placed into special subsection of the text section so
all hot functions appears close together improving locality.
When profile feedback is available, via -fprofile-use, hot functions are automatically detected and this attribute is ignored.
The hot attribute is not implemented in GCC versions earlier
than 4.3.
coldcold attribute is used to inform the compiler that a function is
unlikely executed. The function is optimized for size rather than speed and on
many targets it is placed into special subsection of the text section so all
cold functions appears close together improving code locality of non-cold parts
of program. The paths leading to call of cold functions within code are marked
as unlikely by the branch prediction mechanism. It is thus useful to mark
functions used to handle unlikely conditions, such as perror, as cold to
improve optimization of hot functions that do call marked functions in rare
occasions.
When profile feedback is available, via -fprofile-use, hot functions are automatically detected and this attribute is ignored.
The cold attribute is not implemented in GCC versions earlier than 4.3.
regparm (number)regparm attribute causes the compiler to
pass arguments number one to number if they are of integral type
in registers EAX, EDX, and ECX instead of on the stack. Functions that
take a variable number of arguments will continue to be passed all of their
arguments on the stack.
Beware that on some ELF systems this attribute is unsuitable for
global functions in shared libraries with lazy binding (which is the
default). Lazy binding will send the first call via resolving code in
the loader, which might assume EAX, EDX and ECX can be clobbered, as
per the standard calling conventions. Solaris 8 is affected by this.
GNU systems with GLIBC 2.1 or higher, and FreeBSD, are believed to be
safe since the loaders there save EAX, EDX and ECX. (Lazy binding can be
disabled with the linker or the loader if desired, to avoid the
problem.)
sseregparmsseregparm attribute
causes the compiler to pass up to 3 floating point arguments in
SSE registers instead of on the stack. Functions that take a
variable number of arguments will continue to pass all of their
floating point arguments on the stack.
force_align_arg_pointerforce_align_arg_pointer attribute may be
applied to individual function definitions, generating an alternate
prologue and epilogue that realigns the runtime stack if necessary.
This supports mixing legacy codes that run with a 4-byte aligned stack
with modern codes that keep a 16-byte stack for SSE compatibility.
resbankinterrupt_handler
routines. Saving to the bank is performed automatically after the CPU
accepts an interrupt that uses a register bank.
The nineteen 32-bit registers comprising general register R0 to R14,
control register GBR, and system registers MACH, MACL, and PR and the
vector table address offset are saved into a register bank. Register
banks are stacked in first-in last-out (FILO) sequence. Restoration
from the bank is executed by issuing a RESBANK instruction.
returns_twicereturns_twice attribute tells the compiler that a function may
return more than one time. The compiler will ensure that all registers
are dead before calling such a function and will emit a warning about
the variables that may be clobbered after the second return from the
function. Examples of such functions are setjmp and vfork.
The longjmp-like counterpart of such function, if any, might need
to be marked with the noreturn attribute.
saveallsave_volatilessection ("section-name")text section.
Sometimes, however, you need additional sections, or you need certain
particular functions to appear in special sections. The section
attribute specifies that a function lives in a particular section.
For example, the declaration:
extern void foobar (void) __attribute__ ((section ("bar")));
puts the function foobar in the bar section.
Some file formats do not support arbitrary sections so the section
attribute is not available on all platforms.
If you need to map the entire contents of a module to a particular
section, consider using the facilities of the linker instead.
sentinelNULL. The attribute is only valid on variadic
functions. By default, the sentinel is located at position zero, the
last parameter of the function call. If an optional integer position
argument P is supplied to the attribute, the sentinel must be located at
position P counting backwards from the end of the argument list.
__attribute__ ((sentinel))
is equivalent to
__attribute__ ((sentinel(0)))
The attribute is automatically set with a position of 0 for the built-in
functions execl and execlp. The built-in function
execle has the attribute set with a position of 1.
A valid NULL in this context is defined as zero with any pointer
type. If your system defines the NULL macro with an integer type
then you need to add an explicit cast. GCC replaces stddef.h
with a copy that redefines NULL appropriately.
The warnings for missing or incorrect sentinels are enabled with
-Wformat.
short_callshortcallsignalSee also the interrupt function attribute.
The AVR hardware globally disables interrupts when an interrupt is executed.
Interrupt handler functions defined with the signal attribute
do not re-enable interrupts. It is save to enable interrupts in a
signal handler. This “save” only applies to the code
generated by the compiler and not to the IRQ-layout of the
application which is responsibility of the application.
If both signal and interrupt are specified for the same
function, signal will be silently ignored.
sp_switchinterrupt_handler
function should switch to an alternate stack. It expects a string
argument that names a global variable holding the address of the
alternate stack.
void *alt_stack;
void f () __attribute__ ((interrupt_handler,
sp_switch ("alt_stack")));
stdcallstdcall attribute causes the compiler to
assume that the called function will pop off the stack space used to
pass arguments, unless it takes a variable number of arguments.
syscall_linkagetargettarget attribute is used to specify that a function is to
be compiled with different target options than specified on the
command line. This can be used for instance to have functions
compiled with a different ISA (instruction set architecture) than the
default. You can also use the ‘#pragma GCC target’ pragma to set
more than one function to be compiled with specific target options.
See Function Specific Option Pragmas, for details about the
‘#pragma GCC target’ pragma.
For instance on a 386, you could compile one function with
target("sse4.1,arch=core2") and another with
target("sse4a,arch=amdfam10") that would be equivalent to
compiling the first function with -msse4.1 and
-march=core2 options, and the second function with
-msse4a and -march=amdfam10 options. It is up to the
user to make sure that a function is only invoked on a machine that
supports the particular ISA it was compiled for (for example by using
cpuid on 386 to determine what feature bits and architecture
family are used).
int core2_func (void) __attribute__ ((__target__ ("arch=core2")));
int sse3_func (void) __attribute__ ((__target__ ("sse3")));
On the 386, the following options are allowed:
sin, cos, and
sqrt instructions on the 387 floating point unit.
target("fpmath=sse,387") option must be specified as
target("fpmath=sse+387") because the comma would separate
different options.
On the PowerPC, the following options are allowed:
friz instruction when the
-funsafe-math-optimizations option is used to optimize
rounding a floating point value to 64-bit integer and back to floating
point. The friz instruction does not return the same value if
the floating point number is too large to fit in an integer.
target("cpu=power7") attribute when
generating 32-bit code, VSX and Altivec instructions are not generated
unless you use the -mabi=altivec option on the command line.
target("tune=TUNE") attribute and
you do specify the target("cpu=CPU") attribute,
compilation will tune for the CPU architecture, and not the
default tuning specified on the command line.
On the 386/x86_64 and PowerPC backends, you can use either multiple
strings to specify multiple options, or you can separate the option
with a comma (,).
On the 386/x86_64 and PowerPC backends, the inliner will not inline a
function that has different target options than the caller, unless the
callee has a subset of the target options of the caller. For example
a function declared with target("sse3") can inline a function
with target("sse2"), since -msse3 implies -msse2.
The target attribute is not implemented in GCC versions earlier
than 4.4 for the i386/x86_64 and 4.6 for the PowerPC backends. It is
not currently implemented for other backends.
tiny_datatrap_exitinterrupt_handler to return using
trapa instead of rte. This attribute expects an integer
argument specifying the trap number to be used.
unusedusedWhen applied to a member function of a C++ class template, the
attribute also means that the function will be instantiated if the
class itself is instantiated.
version_id extern int foo () __attribute__((version_id ("20040821")));
Calls to foo will be mapped to calls to foo{20040821}.
visibility ("visibility_type") void __attribute__ ((visibility ("protected")))
f () { /* Do something. */; }
int i __attribute__ ((visibility ("hidden")));
The possible values of visibility_type correspond to the visibility settings in the ELF gABI.
On ELF, default visibility means that the declaration is visible to other modules and, in shared libraries, means that the declared entity may be overridden.
On Darwin, default visibility means that the declaration is visible to other modules.
Default visibility corresponds to “external linkage” in the language.
All visibilities are supported on many, but not all, ELF targets (supported when the assembler supports the ‘.visibility’ pseudo-op). Default visibility is supported everywhere. Hidden visibility is supported on Darwin targets.
The visibility attribute should be applied only to declarations which would otherwise have external linkage. The attribute should be applied consistently, so that the same entity should not be declared with different settings of the attribute.
In C++, the visibility attribute applies to types as well as functions and objects, because in C++ types have linkage. A class must not have greater visibility than its non-static data member types and bases, and class members default to the visibility of their class. Also, a declaration without explicit visibility is limited to the visibility of its type.
In C++, you can mark member functions and static member variables of a class with the visibility attribute. This is useful if you know a particular method or static member variable should only be used from one shared object; then you can mark it hidden while the rest of the class has default visibility. Care must be taken to avoid breaking the One Definition Rule; for example, it is usually not useful to mark an inline method as hidden without marking the whole class as hidden.
A C++ namespace declaration can also have the visibility attribute. This attribute applies only to the particular namespace body, not to other definitions of the same namespace; it is equivalent to using ‘#pragma GCC visibility’ before and after the namespace definition (see Visibility Pragmas).
In C++, if a template argument has limited visibility, this restriction is implicitly propagated to the template instantiation. Otherwise, template instantiations and specializations default to the visibility of their template.
If both the template and enclosing class have explicit visibility, the
visibility from the template is used.
vliwvliw attribute tells the compiler to emit
instructions in VLIW mode instead of core mode. Note that this
attribute is not allowed unless a VLIW coprocessor has been configured
and enabled through command line options.
warn_unused_resultwarn_unused_result attribute causes a warning to be emitted
if a caller of the function with this attribute does not use its
return value. This is useful for functions where not checking
the result is either a security problem or always a bug, such as
realloc.
int fn () __attribute__ ((warn_unused_result));
int foo ()
{
if (fn () < 0) return -1;
fn ();
return 0;
}
results in warning on line 5.
weakweak attribute causes the declaration to be emitted as a weak
symbol rather than a global. This is primarily useful in defining
library functions which can be overridden in user code, though it can
also be used with non-function declarations. Weak symbols are supported
for ELF targets, and also for a.out targets when using the GNU assembler
and linker.
weakrefweakref ("target")weakref attribute marks a declaration as a weak reference.
Without arguments, it should be accompanied by an alias attribute
naming the target symbol. Optionally, the target may be given as
an argument to weakref itself. In either case, weakref
implicitly marks the declaration as weak. Without a
target, given as an argument to weakref or to alias,
weakref is equivalent to weak.
static int x() __attribute__ ((weakref ("y")));
/* is equivalent to... */
static int x() __attribute__ ((weak, weakref, alias ("y")));
/* and to... */
static int x() __attribute__ ((weakref));
static int x() __attribute__ ((alias ("y")));
A weak reference is an alias that does not by itself require a
definition to be given for the target symbol. If the target symbol is
only referenced through weak references, then it becomes a weak
undefined symbol. If it is directly referenced, however, then such
strong references prevail, and a definition will be required for the
symbol, not necessarily in the same translation unit.
The effect is equivalent to moving all references to the alias to a separate translation unit, renaming the alias to the aliased symbol, declaring it as weak, compiling the two separate translation units and performing a reloadable link on them.
At present, a declaration to which weakref is attached can
only be static.
You can specify multiple attributes in a declaration by separating them by commas within the double parentheses or by immediately following an attribute declaration with another attribute declaration.
Some people object to the __attribute__ feature, suggesting that
ISO C's #pragma should be used instead. At the time
__attribute__ was designed, there were two reasons for not doing
this.
#pragma commands from a macro.
#pragma might mean in another
compiler.
These two reasons applied to almost any application that might have been
proposed for #pragma. It was basically a mistake to use
#pragma for anything.
The ISO C99 standard includes _Pragma, which now allows pragmas
to be generated from macros. In addition, a #pragma GCC
namespace is now in use for GCC-specific pragmas. However, it has been
found convenient to use __attribute__ to achieve a natural
attachment of attributes to their corresponding declarations, whereas
#pragma GCC is of use for constructs that do not naturally form
part of the grammar. See Miscellaneous Preprocessing Directives.
This section describes the syntax with which __attribute__ may be
used, and the constructs to which attribute specifiers bind, for the C
language. Some details may vary for C++ and Objective-C. Because of
infelicities in the grammar for attributes, some forms described here
may not be successfully parsed in all cases.
There are some problems with the semantics of attributes in C++. For
example, there are no manglings for attributes, although they may affect
code generation, so problems may arise when attributed types are used in
conjunction with templates or overloading. Similarly, typeid
does not distinguish between types with different attributes. Support
for attributes in C++ may be restricted in future to attributes on
declarations only, but not on nested declarators.
See Function Attributes, for details of the semantics of attributes applying to functions. See Variable Attributes, for details of the semantics of attributes applying to variables. See Type Attributes, for details of the semantics of attributes applying to structure, union and enumerated types.
An attribute specifier is of the form
__attribute__ ((attribute-list)). An attribute list
is a possibly empty comma-separated sequence of attributes, where
each attribute is one of the following:
unused, or a reserved
word such as const).
mode attributes use this form.
format attributes use this form.
format_arg attributes use this form with the list being a single
integer constant expression, and alias attributes use this form
with the list being a single string constant.
An attribute specifier list is a sequence of one or more attribute specifiers, not separated by any other tokens.
In GNU C, an attribute specifier list may appear after the colon following a
label, other than a case or default label. The only
attribute it makes sense to use after a label is unused. This
feature is intended for code generated by programs which contains labels
that may be unused but which is compiled with -Wall. It would
not normally be appropriate to use in it human-written code, though it
could be useful in cases where the code that jumps to the label is
contained within an #ifdef conditional. GNU C++ only permits
attributes on labels if the attribute specifier is immediately
followed by a semicolon (i.e., the label applies to an empty
statement). If the semicolon is missing, C++ label attributes are
ambiguous, as it is permissible for a declaration, which could begin
with an attribute list, to be labelled in C++. Declarations cannot be
labelled in C90 or C99, so the ambiguity does not arise there.
An attribute specifier list may appear as part of a struct,
union or enum specifier. It may go either immediately
after the struct, union or enum keyword, or after
the closing brace. The former syntax is preferred.
Where attribute specifiers follow the closing brace, they are considered
to relate to the structure, union or enumerated type defined, not to any
enclosing declaration the type specifier appears in, and the type
defined is not complete until after the attribute specifiers.
Otherwise, an attribute specifier appears as part of a declaration, counting declarations of unnamed parameters and type names, and relates to that declaration (which may be nested in another declaration, for example in the case of a parameter declaration), or to a particular declarator within a declaration. Where an attribute specifier is applied to a parameter declared as a function or an array, it should apply to the function or array rather than the pointer to which the parameter is implicitly converted, but this is not yet correctly implemented.
Any list of specifiers and qualifiers at the start of a declaration may
contain attribute specifiers, whether or not such a list may in that
context contain storage class specifiers. (Some attributes, however,
are essentially in the nature of storage class specifiers, and only make
sense where storage class specifiers may be used; for example,
section.) There is one necessary limitation to this syntax: the
first old-style parameter declaration in a function definition cannot
begin with an attribute specifier, because such an attribute applies to
the function instead by syntax described below (which, however, is not
yet implemented in this case). In some other cases, attribute
specifiers are permitted by this grammar but not yet supported by the
compiler. All attribute specifiers in this place relate to the
declaration as a whole. In the obsolescent usage where a type of
int is implied by the absence of type specifiers, such a list of
specifiers and qualifiers may be an attribute specifier list with no
other specifiers or qualifiers.
At present, the first parameter in a function prototype must have some
type specifier which is not an attribute specifier; this resolves an
ambiguity in the interpretation of void f(int
(__attribute__((foo)) x)), but is subject to change. At present, if
the parentheses of a function declarator contain only attributes then
those attributes are ignored, rather than yielding an error or warning
or implying a single parameter of type int, but this is subject to
change.
An attribute specifier list may appear immediately before a declarator (other than the first) in a comma-separated list of declarators in a declaration of more than one identifier using a single list of specifiers and qualifiers. Such attribute specifiers apply only to the identifier before whose declarator they appear. For example, in
__attribute__((noreturn)) void d0 (void),
__attribute__((format(printf, 1, 2))) d1 (const char *, ...),
d2 (void)
the noreturn attribute applies to all the functions
declared; the format attribute only applies to d1.
An attribute specifier list may appear immediately before the comma,
= or semicolon terminating the declaration of an identifier other
than a function definition. Such attribute specifiers apply
to the declared object or function. Where an
assembler name for an object or function is specified (see Asm Labels), the attribute must follow the asm
specification.
An attribute specifier list may, in future, be permitted to appear after the declarator in a function definition (before any old-style parameter declarations or the function body).
Attribute specifiers may be mixed with type qualifiers appearing inside
the [] of a parameter array declarator, in the C99 construct by
which such qualifiers are applied to the pointer to which the array is
implicitly converted. Such attribute specifiers apply to the pointer,
not to the array, but at present this is not implemented and they are
ignored.
An attribute specifier list may appear at the start of a nested
declarator. At present, there are some limitations in this usage: the
attributes correctly apply to the declarator, but for most individual
attributes the semantics this implies are not implemented.
When attribute specifiers follow the * of a pointer
declarator, they may be mixed with any type qualifiers present.
The following describes the formal semantics of this syntax. It will make the
most sense if you are familiar with the formal specification of
declarators in the ISO C standard.
Consider (as in C99 subclause 6.7.5 paragraph 4) a declaration T
D1, where T contains declaration specifiers that specify a type
Type (such as int) and D1 is a declarator that
contains an identifier ident. The type specified for ident
for derived declarators whose type does not include an attribute
specifier is as in the ISO C standard.
If D1 has the form ( attribute-specifier-list D ),
and the declaration T D specifies the type
“derived-declarator-type-list Type” for ident, then
T D1 specifies the type “derived-declarator-type-list
attribute-specifier-list Type” for ident.
If D1 has the form *
type-qualifier-and-attribute-specifier-list D, and the
declaration T D specifies the type
“derived-declarator-type-list Type” for ident, then
T D1 specifies the type “derived-declarator-type-list
type-qualifier-and-attribute-specifier-list pointer to Type” for
ident.
For example,
void (__attribute__((noreturn)) ****f) (void);
specifies the type “pointer to pointer to pointer to pointer to
non-returning function returning void”. As another example,
char *__attribute__((aligned(8))) *f;
specifies the type “pointer to 8-byte-aligned pointer to char”.
Note again that this does not work with most attributes; for example,
the usage of ‘aligned’ and ‘noreturn’ attributes given above
is not yet supported.
For compatibility with existing code written for compiler versions that did not implement attributes on nested declarators, some laxity is allowed in the placing of attributes. If an attribute that only applies to types is applied to a declaration, it will be treated as applying to the type of that declaration. If an attribute that only applies to declarations is applied to the type of a declaration, it will be treated as applying to that declaration; and, for compatibility with code placing the attributes immediately before the identifier declared, such an attribute applied to a function return type will be treated as applying to the function type, and such an attribute applied to an array element type will be treated as applying to the array type. If an attribute that only applies to function types is applied to a pointer-to-function type, it will be treated as applying to the pointer target type; if such an attribute is applied to a function return type that is not a pointer-to-function type, it will be treated as applying to the function type.
GNU C extends ISO C to allow a function prototype to override a later old-style non-prototype definition. Consider the following example:
/* Use prototypes unless the compiler is old-fashioned. */ #ifdef __STDC__ #define P(x) x #else #define P(x) () #endif /* Prototype function declaration. */ int isroot P((uid_t)); /* Old-style function definition. */ int isroot (x) /* ??? lossage here ??? */ uid_t x; { return x == 0; }
Suppose the type uid_t happens to be short. ISO C does
not allow this example, because subword arguments in old-style
non-prototype definitions are promoted. Therefore in this example the
function definition's argument is really an int, which does not
match the prototype argument type of short.
This restriction of ISO C makes it hard to write code that is portable
to traditional C compilers, because the programmer does not know
whether the uid_t type is short, int, or
long. Therefore, in cases like these GNU C allows a prototype
to override a later old-style definition. More precisely, in GNU C, a
function prototype argument type overrides the argument type specified
by a later old-style definition if the former type is the same as the
latter type before promotion. Thus in GNU C the above example is
equivalent to the following:
int isroot (uid_t);
int
isroot (uid_t x)
{
return x == 0;
}
GNU C++ does not support old-style function definitions, so this extension is irrelevant.
In GNU C, you may use C++ style comments, which start with ‘//’ and continue until the end of the line. Many other C implementations allow such comments, and they are included in the 1999 C standard. However, C++ style comments are not recognized if you specify an -std option specifying a version of ISO C before C99, or -ansi (equivalent to -std=c90).
In GNU C, you may normally use dollar signs in identifier names. This is because many traditional C implementations allow such identifiers. However, dollar signs in identifiers are not supported on a few target machines, typically because the target assembler does not allow them.
You can use the sequence ‘\e’ in a string or character constant to stand for the ASCII character <ESC>.
The keyword __attribute__ allows you to specify special
attributes of variables or structure fields. This keyword is followed
by an attribute specification inside double parentheses. Some
attributes are currently defined generically for variables.
Other attributes are defined for variables on particular target
systems. Other attributes are available for functions
(see Function Attributes) and for types (see Type Attributes).
Other front ends might define more attributes
(see Extensions to the C++ Language).
You may also specify attributes with ‘__’ preceding and following
each keyword. This allows you to use them in header files without
being concerned about a possible macro of the same name. For example,
you may use __aligned__ instead of aligned.
See Attribute Syntax, for details of the exact syntax for using attributes.
aligned (alignment)int x __attribute__ ((aligned (16))) = 0;
causes the compiler to allocate the global variable x on a
16-byte boundary. On a 68040, this could be used in conjunction with
an asm expression to access the move16 instruction which
requires 16-byte aligned operands.
You can also specify the alignment of structure fields. For example, to
create a double-word aligned int pair, you could write:
struct foo { int x[2] __attribute__ ((aligned (8))); };
This is an alternative to creating a union with a double member
that forces the union to be double-word aligned.
As in the preceding examples, you can explicitly specify the alignment (in bytes) that you wish the compiler to use for a given variable or structure field. Alternatively, you can leave out the alignment factor and just ask the compiler to align a variable or field to the default alignment for the target architecture you are compiling for. The default alignment is sufficient for all scalar types, but may not be enough for all vector types on a target which supports vector operations. The default alignment is fixed for a particular target ABI.
Gcc also provides a target specific macro __BIGGEST_ALIGNMENT__,
which is the largest alignment ever used for any data type on the
target machine you are compiling for. For example, you could write:
short array[3] __attribute__ ((aligned (__BIGGEST_ALIGNMENT__)));
The compiler automatically sets the alignment for the declared
variable or field to __BIGGEST_ALIGNMENT__. Doing this can
often make copy operations more efficient, because the compiler can
use whatever instructions copy the biggest chunks of memory when
performing copies to or from the variables or fields that you have
aligned this way. Note that the value of __BIGGEST_ALIGNMENT__
may change depending on command line options.
When used on a struct, or struct member, the aligned attribute can
only increase the alignment; in order to decrease it, the packed
attribute must be specified as well. When used as part of a typedef, the
aligned attribute can both increase and decrease alignment, and
specifying the packed attribute will generate a warning.
Note that the effectiveness of aligned attributes may be limited
by inherent limitations in your linker. On many systems, the linker is
only able to arrange for variables to be aligned up to a certain maximum
alignment. (For some linkers, the maximum supported alignment may
be very very small.) If your linker is only able to align variables
up to a maximum of 8 byte alignment, then specifying aligned(16)
in an __attribute__ will still only provide you with 8 byte
alignment. See your linker documentation for further information.
The aligned attribute can also be used for functions
(see Function Attributes.)
cleanup (cleanup_function)cleanup attribute runs a function when the variable goes
out of scope. This attribute can only be applied to auto function
scope variables; it may not be applied to parameters or variables
with static storage duration. The function must take one parameter,
a pointer to a type compatible with the variable. The return value
of the function (if any) is ignored.
If -fexceptions is enabled, then cleanup_function
will be run during the stack unwinding that happens during the
processing of the exception. Note that the cleanup attribute
does not allow the exception to be caught, only to perform an action.
It is undefined what happens if cleanup_function does not
return normally.
commonnocommoncommon attribute requests GCC to place a variable in
“common” storage. The nocommon attribute requests the
opposite—to allocate space for it directly.
These attributes override the default chosen by the
-fno-common and -fcommon flags respectively.
deprecateddeprecated (msg)deprecated attribute results in a warning if the variable
is used anywhere in the source file. This is useful when identifying
variables that are expected to be removed in a future version of a
program. The warning also includes the location of the declaration
of the deprecated variable, to enable users to easily find further
information about why the variable is deprecated, or what they should
do instead. Note that the warning only occurs for uses:
extern int old_var __attribute__ ((deprecated));
extern int old_var;
int new_fn () { return old_var; }
results in a warning on line 3 but not line 2. The optional msg argument, which must be a string, will be printed in the warning if present.
The deprecated attribute can also be used for functions and
types (see Function Attributes, see Type Attributes.)
mode (mode)You may also specify a mode of ‘byte’ or ‘__byte__’ to
indicate the mode corresponding to a one-byte integer, ‘word’ or
‘__word__’ for the mode of a one-word integer, and ‘pointer’
or ‘__pointer__’ for the mode used to represent pointers.
packedpacked attribute specifies that a variable or structure field
should have the smallest possible alignment—one byte for a variable,
and one bit for a field, unless you specify a larger value with the
aligned attribute.
Here is a structure in which the field x is packed, so that it
immediately follows a:
struct foo
{
char a;
int x[2] __attribute__ ((packed));
};
Note: The 4.1, 4.2 and 4.3 series of GCC ignore the
packed attribute on bit-fields of type char. This has
been fixed in GCC 4.4 but the change can lead to differences in the
structure layout. See the documentation of
-Wpacked-bitfield-compat for more information.
section ("section-name")data and bss. Sometimes, however, you need additional sections,
or you need certain particular variables to appear in special sections,
for example to map to special hardware. The section
attribute specifies that a variable (or function) lives in a particular
section. For example, this small program uses several specific section names:
struct duart a __attribute__ ((section ("DUART_A"))) = { 0 };
struct duart b __attribute__ ((section ("DUART_B"))) = { 0 };
char stack[10000] __attribute__ ((section ("STACK"))) = { 0 };
int init_data __attribute__ ((section ("INITDATA")));
main()
{
/* Initialize stack pointer */
init_sp (stack + sizeof (stack));
/* Initialize initialized data */
memcpy (&init_data, &data, &edata - &data);
/* Turn on the serial ports */
init_duart (&a);
init_duart (&b);
}
Use the section attribute with
global variables and not local variables,
as shown in the example.
You may use the section attribute with initialized or
uninitialized global variables but the linker requires
each object be defined once, with the exception that uninitialized
variables tentatively go in the common (or bss) section
and can be multiply “defined”. Using the section attribute
will change what section the variable goes into and may cause the
linker to issue an error if an uninitialized variable has multiple
definitions. You can force a variable to be initialized with the
-fno-common flag or the nocommon attribute.
Some file formats do not support arbitrary sections so the section
attribute is not available on all platforms.
If you need to map the entire contents of a module to a particular
section, consider using the facilities of the linker instead.
sharedshared and marking the section
shareable:
int foo __attribute__((section ("shared"), shared)) = 0;
int
main()
{
/* Read and write foo. All running
copies see the same value. */
return 0;
}
You may only use the shared attribute along with section
attribute with a fully initialized global definition because of the way
linkers work. See section attribute for more information.
The shared attribute is only available on Microsoft Windows.
tls_model ("tls_model")tls_model attribute sets thread-local storage model
(see Thread-Local) of a particular __thread variable,
overriding -ftls-model= command-line switch on a per-variable
basis.
The tls_model argument should be one of global-dynamic,
local-dynamic, initial-exec or local-exec.
Not all targets support this attribute.
unusedusedWhen applied to a static data member of a C++ class template, the
attribute also means that the member will be instantiated if the
class itself is instantiated.
vector_size (bytes)int foo __attribute__ ((vector_size (16)));
causes the compiler to set the mode for foo, to be 16 bytes,
divided into int sized units. Assuming a 32-bit int (a vector of
4 units of 4 bytes), the corresponding mode of foo will be V4SI.
This attribute is only applicable to integral and float scalars, although arrays, pointers, and function return values are allowed in conjunction with this construct.
Aggregates with this attribute are invalid, even if they are of the same size as a corresponding scalar. For example, the declaration:
struct S { int a; };
struct S __attribute__ ((vector_size (16))) foo;
is invalid even if the size of the structure is the same as the size of
the int.
selectanyselectany attribute causes an initialized global variable to
have link-once semantics. When multiple definitions of the variable are
encountered by the linker, the first is selected and the remainder are
discarded. Following usage by the Microsoft compiler, the linker is told
not to warn about size or content differences of the multiple
definitions.
Although the primary usage of this attribute is for POD types, the attribute can also be applied to global C++ objects that are initialized by a constructor. In this case, the static initialization and destruction code for the object is emitted in each translation defining the object, but the calls to the constructor and destructor are protected by a link-once guard variable.
The selectany attribute is only available on Microsoft Windows
targets. You can use __declspec (selectany) as a synonym for
__attribute__ ((selectany)) for compatibility with other
compilers.
weakweak attribute is described in Function Attributes.
dllimportdllimport attribute is described in Function Attributes.
dllexportdllexport attribute is described in Function Attributes.
progmemprogmem attribute is used on the AVR to place read-only
data in the non-volatile program memory (flash). The progmem
attribute accomplishes this by putting respective variables into a
section whose name starts with .progmem.
This attribute works similar to the section attribute
but adds additional checking. Notice that just like the
section attribute, progmem affects the location
of the data but not how this data is accessed.
In order to read data located with the progmem attribute
(inline) assembler must be used.
/* Use custom macros from AVR-LibC */
#include <avr/pgmspace.h>
/* Locate var in flash memory */
const int var[2] PROGMEM = { 1, 2 };
int read_var (int i)
{
/* Access var[] by accessor macro from avr/pgmspace.h */
return (int) pgm_read_word (& var[i]);
}
AVR is a Harvard architecture processor and data and read-only data normally resides in the data memory (RAM).
See also the AVR Named Address Spaces section for an alternate way to locate and access data in flash memory.
Three attributes are currently defined for the Blackfin.
l1_datal1_data_Al1_data_Bl1_data attribute will be put into the specific section
named .l1.data. Those with l1_data_A attribute will be put into
the specific section named .l1.data.A. Those with l1_data_B
attribute will be put into the specific section named .l1.data.B.
l2l2 attribute will be put into the specific section
named .l2.data.
One attribute is currently defined for the M32R/D.
model (model-name)small, medium,
or large, representing each of the code models.
Small model objects live in the lower 16MB of memory (so that their
addresses can be loaded with the ld24 instruction).
Medium and large model objects may live anywhere in the 32-bit address space
(the compiler will generate seth/add3 instructions to load their
addresses).
The MeP target has a number of addressing modes and busses. The
near space spans the standard memory space's first 16 megabytes
(24 bits). The far space spans the entire 32-bit memory space.
The based space is a 128 byte region in the memory space which
is addressed relative to the $tp register. The tiny
space is a 65536 byte region relative to the $gp register. In
addition to these memory regions, the MeP target has a separate 16-bit
control bus which is specified with cb attributes.
basedbased attribute will be assigned to the
.based section, and will be accessed with relative to the
$tp register.
tinytiny attribute assigned variables to the
.tiny section, relative to the $gp register.
nearnear attribute are assumed to have addresses
that fit in a 24-bit addressing mode. This is the default for large
variables (-mtiny=4 is the default) but this attribute can
override -mtiny= for small variables, or override -ml.
farfar attribute are addressed using a full
32-bit address. Since this covers the entire memory space, this
allows modules to make no assumptions about where variables might be
stored.
ioio (addr)io attribute are used to address
memory-mapped peripherals. If an address is specified, the variable
is assigned that address, else it is not assigned an address (it is
assumed some other module will assign an address). Example:
int timer_count __attribute__((io(0x123)));
cbcb (addr)cb attribute are used to access the control
bus, using special instructions. addr indicates the control bus
address. Example:
int cpu_clock __attribute__((cb(0x123)));
Two attributes are currently defined for i386 configurations:
ms_struct and gcc_struct
ms_structgcc_structpacked is used on a structure, or if bit-fields are used
it may be that the Microsoft ABI packs them differently
than GCC would normally pack them. Particularly when moving packed
data between functions compiled with GCC and the native Microsoft compiler
(either via function call or as data in a file), it may be necessary to access
either format.
Currently -m[no-]ms-bitfields is provided for the Microsoft Windows X86 compilers to match the native Microsoft compiler.
The Microsoft structure layout algorithm is fairly simple with the exception of the bitfield packing:
The padding and alignment of members of structures and whether a bit field can straddle a storage-unit boundary
offset % alignment-requirement == 0
Handling of zero-length bitfields:
MSVC interprets zero-length bitfields in the following ways:
For example:
struct
{
unsigned long bf_1 : 12;
unsigned long : 0;
unsigned long bf_2 : 12;
} t1;
The size of t1 would be 8 bytes with the zero-length bitfield. If the
zero-length bitfield were removed, t1's size would be 4 bytes.
foo, and the
alignment of the zero-length bitfield is greater than the member that follows it,
bar, bar will be aligned as the type of the zero-length bitfield.
For example:
struct
{
char foo : 4;
short : 0;
char bar;
} t2;
struct
{
char foo : 4;
short : 0;
double bar;
} t3;
For t2, bar will be placed at offset 2, rather than offset 1.
Accordingly, the size of t2 will be 4. For t3, the zero-length
bitfield will not affect the alignment of bar or, as a result, the size
of the structure.
Taking this into account, it is important to note the following:
t2 has a size of 4 bytes, since the zero-length bitfield follows a
normal bitfield, and is of type short.
struct
{
char foo : 6;
long : 0;
} t4;
Here, t4 will take up 4 bytes.
struct
{
char foo;
long : 0;
char bar;
} t5;
Here, t5 will take up 2 bytes.
Three attributes currently are defined for PowerPC configurations:
altivec, ms_struct and gcc_struct.
For full documentation of the struct attributes please see the documentation in i386 Variable Attributes.
For documentation of altivec attribute please see the
documentation in PowerPC Type Attributes.
The SPU supports the spu_vector attribute for variables. For
documentation of this attribute please see the documentation in
SPU Type Attributes.
One attribute is currently defined for xstormy16 configurations:
below100.
below100below100 attribute (BELOW100 is
allowed also), GCC will place the variable in the first 0x100 bytes of
memory and use special opcodes to access it. Such variables will be
placed in either the .bss_below100 section or the
.data_below100 section.
The keyword __attribute__ allows you to specify special
attributes of struct and union types when you define
such types. This keyword is followed by an attribute specification
inside double parentheses. Seven attributes are currently defined for
types: aligned, packed, transparent_union,
unused, deprecated, visibility, and
may_alias. Other attributes are defined for functions
(see Function Attributes) and for variables (see Variable Attributes).
You may also specify any one of these attributes with ‘__’
preceding and following its keyword. This allows you to use these
attributes in header files without being concerned about a possible
macro of the same name. For example, you may use __aligned__
instead of aligned.
You may specify type attributes in an enum, struct or union type
declaration or definition, or for other types in a typedef
declaration.
For an enum, struct or union type, you may specify attributes either between the enum, struct or union tag and the name of the type, or just past the closing curly brace of the definition. The former syntax is preferred.
See Attribute Syntax, for details of the exact syntax for using attributes.
aligned (alignment) struct S { short f[3]; } __attribute__ ((aligned (8)));
typedef int more_aligned_int __attribute__ ((aligned (8)));
force the compiler to insure (as far as it can) that each variable whose
type is struct S or more_aligned_int will be allocated and
aligned at least on a 8-byte boundary. On a SPARC, having all
variables of type struct S aligned to 8-byte boundaries allows
the compiler to use the ldd and std (doubleword load and
store) instructions when copying one variable of type struct S to
another, thus improving run-time efficiency.
Note that the alignment of any given struct or union type
is required by the ISO C standard to be at least a perfect multiple of
the lowest common multiple of the alignments of all of the members of
the struct or union in question. This means that you can
effectively adjust the alignment of a struct or union
type by attaching an aligned attribute to any one of the members
of such a type, but the notation illustrated in the example above is a
more obvious, intuitive, and readable way to request the compiler to
adjust the alignment of an entire struct or union type.
As in the preceding example, you can explicitly specify the alignment
(in bytes) that you wish the compiler to use for a given struct
or union type. Alternatively, you can leave out the alignment factor
and just ask the compiler to align a type to the maximum
useful alignment for the target machine you are compiling for. For
example, you could write:
struct S { short f[3]; } __attribute__ ((aligned));
Whenever you leave out the alignment factor in an aligned
attribute specification, the compiler automatically sets the alignment
for the type to the largest alignment which is ever used for any data
type on the target machine you are compiling for. Doing this can often
make copy operations more efficient, because the compiler can use
whatever instructions copy the biggest chunks of memory when performing
copies to or from the variables which have types that you have aligned
this way.
In the example above, if the size of each short is 2 bytes, then
the size of the entire struct S type is 6 bytes. The smallest
power of two which is greater than or equal to that is 8, so the
compiler sets the alignment for the entire struct S type to 8
bytes.
Note that although you can ask the compiler to select a time-efficient alignment for a given type and then declare only individual stand-alone objects of that type, the compiler's ability to select a time-efficient alignment is primarily useful only when you plan to create arrays of variables having the relevant (efficiently aligned) type. If you declare or use arrays of variables of an efficiently-aligned type, then it is likely that your program will also be doing pointer arithmetic (or subscripting, which amounts to the same thing) on pointers to the relevant type, and the code that the compiler generates for these pointer arithmetic operations will often be more efficient for efficiently-aligned types than for other types.
The aligned attribute can only increase the alignment; but you
can decrease it by specifying packed as well. See below.
Note that the effectiveness of aligned attributes may be limited
by inherent limitations in your linker. On many systems, the linker is
only able to arrange for variables to be aligned up to a certain maximum
alignment. (For some linkers, the maximum supported alignment may
be very very small.) If your linker is only able to align variables
up to a maximum of 8 byte alignment, then specifying aligned(16)
in an __attribute__ will still only provide you with 8 byte
alignment. See your linker documentation for further information.
packedstruct or union type
definition, specifies that each member (other than zero-width bitfields)
of the structure or union is placed to minimize the memory required. When
attached to an enum definition, it indicates that the smallest
integral type should be used.
Specifying this attribute for struct and union types is
equivalent to specifying the packed attribute on each of the
structure or union members. Specifying the -fshort-enums
flag on the line is equivalent to specifying the packed
attribute on all enum definitions.
In the following example struct my_packed_struct's members are
packed closely together, but the internal layout of its s member
is not packed—to do that, struct my_unpacked_struct would need to
be packed too.
struct my_unpacked_struct
{
char c;
int i;
};
struct __attribute__ ((__packed__)) my_packed_struct
{
char c;
int i;
struct my_unpacked_struct s;
};
You may only specify this attribute on the definition of an enum,
struct or union, not on a typedef which does not
also define the enumerated type, structure or union.
transparent_unionunion type definition, indicates
that any function parameter having that union type causes calls to that
function to be treated in a special way.
First, the argument corresponding to a transparent union type can be of
any type in the union; no cast is required. Also, if the union contains
a pointer type, the corresponding argument can be a null pointer
constant or a void pointer expression; and if the union contains a void
pointer type, the corresponding argument can be any pointer expression.
If the union member type is a pointer, qualifiers like const on
the referenced type must be respected, just as with normal pointer
conversions.
Second, the argument is passed to the function using the calling conventions of the first member of the transparent union, not the calling conventions of the union itself. All members of the union must have the same machine representation; this is necessary for this argument passing to work properly.
Transparent unions are designed for library functions that have multiple
interfaces for compatibility reasons. For example, suppose the
wait function must accept either a value of type int * to
comply with Posix, or a value of type union wait * to comply with
the 4.1BSD interface. If wait's parameter were void *,
wait would accept both kinds of arguments, but it would also
accept any other pointer type and this would make argument type checking
less useful. Instead, <sys/wait.h> might define the interface
as follows:
typedef union __attribute__ ((__transparent_union__))
{
int *__ip;
union wait *__up;
} wait_status_ptr_t;
pid_t wait (wait_status_ptr_t);
This interface allows either int * or union wait *
arguments to be passed, using the int * calling convention.
The program can call wait with arguments of either type:
int w1 () { int w; return wait (&w); }
int w2 () { union wait w; return wait (&w); }
With this interface, wait's implementation might look like this:
pid_t wait (wait_status_ptr_t p)
{
return waitpid (-1, p.__ip, 0);
}
unusedunion or a struct),
this attribute means that variables of that type are meant to appear
possibly unused. GCC will not produce a warning for any variables of
that type, even if the variable appears to do nothing. This is often
the case with lock or thread classes, which are usually defined and then
not referenced, but contain constructors and destructors that have
nontrivial bookkeeping functions.
deprecateddeprecated (msg)deprecated attribute results in a warning if the type
is used anywhere in the source file. This is useful when identifying
types that are expected to be removed in a future version of a program.
If possible, the warning also includes the location of the declaration
of the deprecated type, to enable users to easily find further
information about why the type is deprecated, or what they should do
instead. Note that the warnings only occur for uses and then only
if the type is being applied to an identifier that itself is not being
declared as deprecated.
typedef int T1 __attribute__ ((deprecated));
T1 x;
typedef T1 T2;
T2 y;
typedef T1 T3 __attribute__ ((deprecated));
T3 z __attribute__ ((deprecated));
results in a warning on line 2 and 3 but not lines 4, 5, or 6. No warning is issued for line 4 because T2 is not explicitly deprecated. Line 5 has no warning because T3 is explicitly deprecated. Similarly for line 6. The optional msg argument, which must be a string, will be printed in the warning if present.
The deprecated attribute can also be used for functions and
variables (see Function Attributes, see Variable Attributes.)
may_aliasNote that an object of a type with this attribute does not have any special semantics.
Example of use:
typedef short __attribute__((__may_alias__)) short_a;
int
main (void)
{
int a = 0x12345678;
short_a *b = (short_a *) &a;
b[1] = 0;
if (a == 0x12345678)
abort();
exit(0);
}
If you replaced short_a with short in the variable
declaration, the above program would abort when compiled with
-fstrict-aliasing, which is on by default at -O2 or
above in recent GCC versions.
visibilityNote that the type visibility is applied to vague linkage entities associated with the class (vtable, typeinfo node, etc.). In particular, if a class is thrown as an exception in one shared object and caught in another, the class must have default visibility. Otherwise the two shared objects will be unable to use the same typeinfo node and exception handling will break.
On those ARM targets that support dllimport (such as Symbian
OS), you can use the notshared attribute to indicate that the
virtual table and other similar data for a class should not be
exported from a DLL. For example:
class __declspec(notshared) C {
public:
__declspec(dllimport) C();
virtual void f();
}
__declspec(dllexport)
C::C() {}
In this code, C::C is exported from the current DLL, but the
virtual table for C is not exported. (You can use
__attribute__ instead of __declspec if you prefer, but
most Symbian OS code uses __declspec.)
Many of the MeP variable attributes may be applied to types as well.
Specifically, the based, tiny, near, and
far attributes may be applied to either. The io and
cb attributes may not be applied to types.
Two attributes are currently defined for i386 configurations:
ms_struct and gcc_struct.
ms_structgcc_structpacked is used on a structure, or if bit-fields are used
it may be that the Microsoft ABI packs them differently
than GCC would normally pack them. Particularly when moving packed
data between functions compiled with GCC and the native Microsoft compiler
(either via function call or as data in a file), it may be necessary to access
either format.
Currently -m[no-]ms-bitfields is provided for the Microsoft Windows X86 compilers to match the native Microsoft compiler.
To specify multiple attributes, separate them by commas within the double parentheses: for example, ‘__attribute__ ((aligned (16), packed))’.
Three attributes currently are defined for PowerPC configurations:
altivec, ms_struct and gcc_struct.
For full documentation of the ms_struct and gcc_struct
attributes please see the documentation in i386 Type Attributes.
The altivec attribute allows one to declare AltiVec vector data
types supported by the AltiVec Programming Interface Manual. The
attribute requires an argument to specify one of three vector types:
vector__, pixel__ (always followed by unsigned short),
and bool__ (always followed by unsigned).
__attribute__((altivec(vector__)))
__attribute__((altivec(pixel__))) unsigned short
__attribute__((altivec(bool__))) unsigned
These attributes mainly are intended to support the __vector,
__pixel, and __bool AltiVec keywords.
The SPU supports the spu_vector attribute for types. This attribute
allows one to declare vector data types supported by the Sony/Toshiba/IBM SPU
Language Extensions Specification. It is intended to support the
__vector keyword.
The keyword __alignof__ allows you to inquire about how an object
is aligned, or the minimum alignment usually required by a type. Its
syntax is just like sizeof.
For example, if the target machine requires a double value to be
aligned on an 8-byte boundary, then __alignof__ (double) is 8.
This is true on many RISC machines. On more traditional machine
designs, __alignof__ (double) is 4 or even 2.
Some machines never actually require alignment; they allow reference to any
data type even at an odd address. For these machines, __alignof__
reports the smallest alignment that GCC will give the data type, usually as
mandated by the target ABI.
If the operand of __alignof__ is an lvalue rather than a type,
its value is the required alignment for its type, taking into account
any minimum alignment specified with GCC's __attribute__
extension (see Variable Attributes). For example, after this
declaration:
struct foo { int x; char y; } foo1;
the value of __alignof__ (foo1.y) is 1, even though its actual
alignment is probably 2 or 4, the same as __alignof__ (int).
It is an error to ask for the alignment of an incomplete type.
By declaring a function inline, you can direct GCC to make calls to that function faster. One way GCC can achieve this is to integrate that function's code into the code for its callers. This makes execution faster by eliminating the function-call overhead; in addition, if any of the actual argument values are constant, their known values may permit simplifications at compile time so that not all of the inline function's code needs to be included. The effect on code size is less predictable; object code may be larger or smaller with function inlining, depending on the particular case. You can also direct GCC to try to integrate all “simple enough” functions into their callers with the option -finline-functions.
GCC implements three different semantics of declaring a function
inline. One is available with -std=gnu89 or
-fgnu89-inline or when gnu_inline attribute is present
on all inline declarations, another when
-std=c99, -std=c11,
-std=gnu99 or -std=gnu11
(without -fgnu89-inline), and the third
is used when compiling C++.
To declare a function inline, use the inline keyword in its
declaration, like this:
static inline int
inc (int *a)
{
return (*a)++;
}
If you are writing a header file to be included in ISO C90 programs, write
__inline__ instead of inline. See Alternate Keywords.
The three types of inlining behave similarly in two important cases:
when the inline keyword is used on a static function,
like the example above, and when a function is first declared without
using the inline keyword and then is defined with
inline, like this:
extern int inc (int *a);
inline int
inc (int *a)
{
return (*a)++;
}
In both of these common cases, the program behaves the same as if you
had not used the inline keyword, except for its speed.
When a function is both inline and static, if all calls to the
function are integrated into the caller, and the function's address is
never used, then the function's own assembler code is never referenced.
In this case, GCC does not actually output assembler code for the
function, unless you specify the option -fkeep-inline-functions.
Some calls cannot be integrated for various reasons (in particular,
calls that precede the function's definition cannot be integrated, and
neither can recursive calls within the definition). If there is a
nonintegrated call, then the function is compiled to assembler code as
usual. The function must also be compiled as usual if the program
refers to its address, because that can't be inlined.
Note that certain usages in a function definition can make it unsuitable
for inline substitution. Among these usages are: use of varargs, use of
alloca, use of variable sized data types (see Variable Length),
use of computed goto (see Labels as Values), use of nonlocal goto,
and nested functions (see Nested Functions). Using -Winline
will warn when a function marked inline could not be substituted,
and will give the reason for the failure.
As required by ISO C++, GCC considers member functions defined within
the body of a class to be marked inline even if they are
not explicitly declared with the inline keyword. You can
override this with -fno-default-inline; see Options Controlling C++ Dialect.
GCC does not inline any functions when not optimizing unless you specify the ‘always_inline’ attribute for the function, like this:
/* Prototype. */
inline void foo (const char) __attribute__((always_inline));
The remainder of this section is specific to GNU C90 inlining.
When an inline function is not static, then the compiler must assume
that there may be calls from other source files; since a global symbol can
be defined only once in any program, the function must not be defined in
the other source files, so the calls therein cannot be integrated.
Therefore, a non-static inline function is always compiled on its
own in the usual fashion.
If you specify both inline and extern in the function
definition, then the definition is used only for inlining. In no case
is the function compiled on its own, not even if you refer to its
address explicitly. Such an address becomes an external reference, as
if you had only declared the function, and had not defined it.
This combination of inline and extern has almost the
effect of a macro. The way to use it is to put a function definition in
a header file with these keywords, and put another copy of the
definition (lacking inline and extern) in a library file.
The definition in the header file will cause most calls to the function
to be inlined. If any uses of the function remain, they will refer to
the single copy in the library.
C has the concept of volatile objects. These are normally accessed by pointers and used for accessing hardware or inter-thread communication. The standard encourages compilers to refrain from optimizations concerning accesses to volatile objects, but leaves it implementation defined as to what constitutes a volatile access. The minimum requirement is that at a sequence point all previous accesses to volatile objects have stabilized and no subsequent accesses have occurred. Thus an implementation is free to reorder and combine volatile accesses which occur between sequence points, but cannot do so for accesses across a sequence point. The use of volatile does not allow you to violate the restriction on updating objects multiple times between two sequence points.
Accesses to non-volatile objects are not ordered with respect to volatile accesses. You cannot use a volatile object as a memory barrier to order a sequence of writes to non-volatile memory. For instance:
int *ptr = something;
volatile int vobj;
*ptr = something;
vobj = 1;
Unless *ptr and vobj can be aliased, it is not guaranteed that the write to *ptr will have occurred by the time the update of vobj has happened. If you need this guarantee, you must use a stronger memory barrier such as:
int *ptr = something;
volatile int vobj;
*ptr = something;
asm volatile ("" : : : "memory");
vobj = 1;
A scalar volatile object is read when it is accessed in a void context:
volatile int *src = somevalue;
*src;
Such expressions are rvalues, and GCC implements this as a read of the volatile object being pointed to.
Assignments are also expressions and have an rvalue. However when assigning to a scalar volatile, the volatile object is not reread, regardless of whether the assignment expression's rvalue is used or not. If the assignment's rvalue is used, the value is that assigned to the volatile object. For instance, there is no read of vobj in all the following cases:
int obj;
volatile int vobj;
vobj = something;
obj = vobj = something;
obj ? vobj = onething : vobj = anotherthing;
obj = (something, vobj = anotherthing);
If you need to read the volatile object after an assignment has occurred, you must use a separate expression with an intervening sequence point.
As bitfields are not individually addressable, volatile bitfields may be implicitly read when written to, or when adjacent bitfields are accessed. Bitfield operations may be optimized such that adjacent bitfields are only partially accessed, if they straddle a storage unit boundary. For these reasons it is unwise to use volatile bitfields to access hardware.
In an assembler instruction using asm, you can specify the
operands of the instruction using C expressions. This means you need not
guess which registers or memory locations will contain the data you want
to use.
You must specify an assembler instruction template much like what appears in a machine description, plus an operand constraint string for each operand.
For example, here is how to use the 68881's fsinx instruction:
asm ("fsinx %1,%0" : "=f" (result) : "f" (angle));
Here angle is the C expression for the input operand while
result is that of the output operand. Each has ‘"f"’ as its
operand constraint, saying that a floating point register is required.
The ‘=’ in ‘=f’ indicates that the operand is an output; all
output operands' constraints must use ‘=’. The constraints use the
same language used in the machine description (see Constraints).
Each operand is described by an operand-constraint string followed by the C expression in parentheses. A colon separates the assembler template from the first output operand and another separates the last output operand from the first input, if any. Commas separate the operands within each group. The total number of operands is currently limited to 30; this limitation may be lifted in some future version of GCC.
If there are no output operands but there are input operands, you must place two consecutive colons surrounding the place where the output operands would go.
As of GCC version 3.1, it is also possible to specify input and output
operands using symbolic names which can be referenced within the
assembler code. These names are specified inside square brackets
preceding the constraint string, and can be referenced inside the
assembler code using %[name] instead of a percentage sign
followed by the operand number. Using named operands the above example
could look like:
asm ("fsinx %[angle],%[output]"
: [output] "=f" (result)
: [angle] "f" (angle));
Note that the symbolic operand names have no relation whatsoever to other C identifiers. You may use any name you like, even those of existing C symbols, but you must ensure that no two operands within the same assembler construct use the same symbolic name.
Output operand expressions must be lvalues; the compiler can check this.
The input operands need not be lvalues. The compiler cannot check
whether the operands have data types that are reasonable for the
instruction being executed. It does not parse the assembler instruction
template and does not know what it means or even whether it is valid
assembler input. The extended asm feature is most often used for
machine instructions the compiler itself does not know exist. If
the output expression cannot be directly addressed (for example, it is a
bit-field), your constraint must allow a register. In that case, GCC
will use the register as the output of the asm, and then store
that register into the output.
The ordinary output operands must be write-only; GCC will assume that the values in these operands before the instruction are dead and need not be generated. Extended asm supports input-output or read-write operands. Use the constraint character ‘+’ to indicate such an operand and list it with the output operands. You should only use read-write operands when the constraints for the operand (or the operand in which only some of the bits are to be changed) allow a register.
You may, as an alternative, logically split its function into two
separate operands, one input operand and one write-only output
operand. The connection between them is expressed by constraints
which say they need to be in the same location when the instruction
executes. You can use the same C expression for both operands, or
different expressions. For example, here we write the (fictitious)
‘combine’ instruction with bar as its read-only source
operand and foo as its read-write destination:
asm ("combine %2,%0" : "=r" (foo) : "0" (foo), "g" (bar));
The constraint ‘"0"’ for operand 1 says that it must occupy the same location as operand 0. A number in constraint is allowed only in an input operand and it must refer to an output operand.
Only a number in the constraint can guarantee that one operand will be in
the same place as another. The mere fact that foo is the value
of both operands is not enough to guarantee that they will be in the
same place in the generated assembler code. The following would not
work reliably:
asm ("combine %2,%0" : "=r" (foo) : "r" (foo), "g" (bar));
Various optimizations or reloading could cause operands 0 and 1 to be in
different registers; GCC knows no reason not to do so. For example, the
compiler might find a copy of the value of foo in one register and
use it for operand 1, but generate the output operand 0 in a different
register (copying it afterward to foo's own address). Of course,
since the register for operand 1 is not even mentioned in the assembler
code, the result will not work, but GCC can't tell that.
As of GCC version 3.1, one may write [name] instead of
the operand number for a matching constraint. For example:
asm ("cmoveq %1,%2,%[result]"
: [result] "=r"(result)
: "r" (test), "r"(new), "[result]"(old));
Sometimes you need to make an asm operand be a specific register,
but there's no matching constraint letter for that register by
itself. To force the operand into that register, use a local variable
for the operand and specify the register in the variable declaration.
See Explicit Reg Vars. Then for the asm operand, use any
register constraint letter that matches the register:
register int *p1 asm ("r0") = ...;
register int *p2 asm ("r1") = ...;
register int *result asm ("r0");
asm ("sysint" : "=r" (result) : "0" (p1), "r" (p2));
In the above example, beware that a register that is call-clobbered by
the target ABI will be overwritten by any function call in the
assignment, including library calls for arithmetic operators.
Also a register may be clobbered when generating some operations,
like variable shift, memory copy or memory move on x86.
Assuming it is a call-clobbered register, this may happen to r0
above by the assignment to p2. If you have to use such a
register, use temporary variables for expressions between the register
assignment and use:
int t1 = ...;
register int *p1 asm ("r0") = ...;
register int *p2 asm ("r1") = t1;
register int *result asm ("r0");
asm ("sysint" : "=r" (result) : "0" (p1), "r" (p2));
Some instructions clobber specific hard registers. To describe this, write a third colon after the input operands, followed by the names of the clobbered hard registers (given as strings). Here is a realistic example for the VAX:
asm volatile ("movc3 %0,%1,%2"
: /* no outputs */
: "g" (from), "g" (to), "g" (count)
: "r0", "r1", "r2", "r3", "r4", "r5");
You may not write a clobber description in a way that overlaps with an
input or output operand. For example, you may not have an operand
describing a register class with one member if you mention that register
in the clobber list. Variables declared to live in specific registers
(see Explicit Reg Vars), and used as asm input or output operands must
have no part mentioned in the clobber description.
There is no way for you to specify that an input
operand is modified without also specifying it as an output
operand. Note that if all the output operands you specify are for this
purpose (and hence unused), you will then also need to specify
volatile for the asm construct, as described below, to
prevent GCC from deleting the asm statement as unused.
If you refer to a particular hardware register from the assembler code, you will probably have to list the register after the third colon to tell the compiler the register's value is modified. In some assemblers, the register names begin with ‘%’; to produce one ‘%’ in the assembler code, you must write ‘%%’ in the input.
If your assembler instruction can alter the condition code register, add ‘cc’ to the list of clobbered registers. GCC on some machines represents the condition codes as a specific hardware register; ‘cc’ serves to name this register. On other machines, the condition code is handled differently, and specifying ‘cc’ has no effect. But it is valid no matter what the machine.
If your assembler instructions access memory in an unpredictable
fashion, add ‘memory’ to the list of clobbered registers. This
will cause GCC to not keep memory values cached in registers across the
assembler instruction and not optimize stores or loads to that memory.
You will also want to add the volatile keyword if the memory
affected is not listed in the inputs or outputs of the asm, as
the ‘memory’ clobber does not count as a side-effect of the
asm. If you know how large the accessed memory is, you can add
it as input or output but if this is not known, you should add
‘memory’. As an example, if you access ten bytes of a string, you
can use a memory input like:
{"m"( ({ struct { char x[10]; } *p = (void *)ptr ; *p; }) )}.
Note that in the following example the memory input is necessary,
otherwise GCC might optimize the store to x away:
int foo ()
{
int x = 42;
int *y = &x;
int result;
asm ("magic stuff accessing an 'int' pointed to by '%1'"
"=&d" (r) : "a" (y), "m" (*y));
return result;
}
You can put multiple assembler instructions together in a single
asm template, separated by the characters normally used in assembly
code for the system. A combination that works in most places is a newline
to break the line, plus a tab character to move to the instruction field
(written as ‘\n\t’). Sometimes semicolons can be used, if the
assembler allows semicolons as a line-breaking character. Note that some
assembler dialects use semicolons to start a comment.
The input operands are guaranteed not to use any of the clobbered
registers, and neither will the output operands' addresses, so you can
read and write the clobbered registers as many times as you like. Here
is an example of multiple instructions in a template; it assumes the
subroutine _foo accepts arguments in registers 9 and 10:
asm ("movl %0,r9\n\tmovl %1,r10\n\tcall _foo"
: /* no outputs */
: "g" (from), "g" (to)
: "r9", "r10");
Unless an output operand has the ‘&’ constraint modifier, GCC may allocate it in the same register as an unrelated input operand, on the assumption the inputs are consumed before the outputs are produced. This assumption may be false if the assembler code actually consists of more than one instruction. In such a case, use ‘&’ for each output operand that may not overlap an input. See Modifiers.
If you want to test the condition code produced by an assembler
instruction, you must include a branch and a label in the asm
construct, as follows:
asm ("clr %0\n\tfrob %1\n\tbeq 0f\n\tmov #1,%0\n0:"
: "g" (result)
: "g" (input));
This assumes your assembler supports local labels, as the GNU assembler and most Unix assemblers do.
Speaking of labels, jumps from one asm to another are not
supported. The compiler's optimizers do not know about these jumps, and
therefore they cannot take account of them when deciding how to
optimize. See Extended asm with goto.
Usually the most convenient way to use these asm instructions is to
encapsulate them in macros that look like functions. For example,
#define sin(x) \
({ double __value, __arg = (x); \
asm ("fsinx %1,%0": "=f" (__value): "f" (__arg)); \
__value; })
Here the variable __arg is used to make sure that the instruction
operates on a proper double value, and to accept only those
arguments x which can convert automatically to a double.
Another way to make sure the instruction operates on the correct data
type is to use a cast in the asm. This is different from using a
variable __arg in that it converts more different types. For
example, if the desired type were int, casting the argument to
int would accept a pointer with no complaint, while assigning the
argument to an int variable named __arg would warn about
using a pointer unless the caller explicitly casts it.
If an asm has output operands, GCC assumes for optimization
purposes the instruction has no side effects except to change the output
operands. This does not mean instructions with a side effect cannot be
used, but you must be careful, because the compiler may eliminate them
if the output operands aren't used, or move them out of loops, or
replace two with one if they constitute a common subexpression. Also,
if your instruction does have a side effect on a variable that otherwise
appears not to change, the old value of the variable may be reused later
if it happens to be found in a register.
You can prevent an asm instruction from being deleted
by writing the keyword volatile after
the asm. For example:
#define get_and_set_priority(new) \
({ int __old; \
asm volatile ("get_and_set_priority %0, %1" \
: "=g" (__old) : "g" (new)); \
__old; })
The volatile keyword indicates that the instruction has
important side-effects. GCC will not delete a volatile asm if
it is reachable. (The instruction can still be deleted if GCC can
prove that control-flow will never reach the location of the
instruction.) Note that even a volatile asm instruction
can be moved relative to other code, including across jump
instructions. For example, on many targets there is a system
register which can be set to control the rounding mode of
floating point operations. You might try
setting it with a volatile asm, like this PowerPC example:
asm volatile("mtfsf 255,%0" : : "f" (fpenv));
sum = x + y;
This will not work reliably, as the compiler may move the addition back
before the volatile asm. To make it work you need to add an
artificial dependency to the asm referencing a variable in the code
you don't want moved, for example:
asm volatile ("mtfsf 255,%1" : "=X"(sum): "f"(fpenv));
sum = x + y;
Similarly, you can't expect a
sequence of volatile asm instructions to remain perfectly
consecutive. If you want consecutive output, use a single asm.
Also, GCC will perform some optimizations across a volatile asm
instruction; GCC does not “forget everything” when it encounters
a volatile asm instruction the way some other compilers do.
An asm instruction without any output operands will be treated
identically to a volatile asm instruction.
It is a natural idea to look for a way to give access to the condition code left by the assembler instruction. However, when we attempted to implement this, we found no way to make it work reliably. The problem is that output operands might need reloading, which would result in additional following “store” instructions. On most machines, these instructions would alter the condition code before there was time to test it. This problem doesn't arise for ordinary “test” and “compare” instructions because they don't have any output operands.
For reasons similar to those described above, it is not possible to give an assembler instruction access to the condition code left by previous instructions.
As of GCC version 4.5, asm goto may be used to have the assembly
jump to one or more C labels. In this form, a fifth section after the
clobber list contains a list of all C labels to which the assembly may jump.
Each label operand is implicitly self-named. The asm is also assumed
to fall through to the next statement.
This form of asm is restricted to not have outputs. This is due
to a internal restriction in the compiler that control transfer instructions
cannot have outputs. This restriction on asm goto may be lifted
in some future version of the compiler. In the mean time, asm goto
may include a memory clobber, and so leave outputs in memory.
int frob(int x)
{
int y;
asm goto ("frob %%r5, %1; jc %l[error]; mov (%2), %%r5"
: : "r"(x), "r"(&y) : "r5", "memory" : error);
return y;
error:
return -1;
}
In this (inefficient) example, the frob instruction sets the
carry bit to indicate an error. The jc instruction detects
this and branches to the error label. Finally, the output
of the frob instruction (%r5) is stored into the memory
for variable y, which is later read by the return statement.
void doit(void)
{
int i = 0;
asm goto ("mfsr %%r1, 123; jmp %%r1;"
".pushsection doit_table;"
".long %l0, %l1, %l2, %l3;"
".popsection"
: : : "r1" : label1, label2, label3, label4);
__builtin_unreachable ();
label1:
f1();
return;
label2:
f2();
return;
label3:
i = 1;
label4:
f3(i);
}
In this (also inefficient) example, the mfsr instruction reads
an address from some out-of-band machine register, and the following
jmp instruction branches to that address. The address read by
the mfsr instruction is assumed to have been previously set via
some application-specific mechanism to be one of the four values stored
in the doit_table section. Finally, the asm is followed
by a call to __builtin_unreachable to indicate that the asm
does not in fact fall through.
#define TRACE1(NUM) \
do { \
asm goto ("0: nop;" \
".pushsection trace_table;" \
".long 0b, %l0;" \
".popsection" \
: : : : trace#NUM); \
if (0) { trace#NUM: trace(); } \
} while (0)
#define TRACE TRACE1(__COUNTER__)
In this example (which in fact inspired the asm goto feature)
we want on rare occasions to call the trace function; on other
occasions we'd like to keep the overhead to the absolute minimum.
The normal code path consists of a single nop instruction.
However, we record the address of this nop together with the
address of a label that calls the trace function. This allows
the nop instruction to be patched at runtime to be an
unconditional branch to the stored label. It is assumed that an
optimizing compiler will move the labeled block out of line, to
optimize the fall through path from the asm.
If you are writing a header file that should be includable in ISO C
programs, write __asm__ instead of asm. See Alternate Keywords.
asmSome targets require that GCC track the size of each instruction used in
order to generate correct code. Because the final length of an
asm is only known by the assembler, GCC must make an estimate as
to how big it will be. The estimate is formed by counting the number of
statements in the pattern of the asm and multiplying that by the
length of the longest instruction on that processor. Statements in the
asm are identified by newline characters and whatever statement
separator characters are supported by the assembler; on most processors
this is the `;' character.
Normally, GCC's estimate is perfectly adequate to ensure that correct code is generated, but it is possible to confuse the compiler if you use pseudo instructions or assembler macros that expand into multiple real instructions or if you use assembler directives that expand to more space in the object file than would be needed for a single instruction. If this happens then the assembler will produce a diagnostic saying that a label is unreachable.
There are several rules on the usage of stack-like regs in asm_operands insns. These rules apply only to the operands that are stack-like regs:
An input reg that is implicitly popped by the asm must be explicitly clobbered, unless it is constrained to match an output operand.
All implicitly popped input regs must be closer to the top of the reg-stack than any input that is not implicitly popped.
It is possible that if an input dies in an insn, reload might use the input reg for an output reload. Consider this example:
asm ("foo" : "=t" (a) : "f" (b));
This asm says that input B is not popped by the asm, and that the asm pushes a result onto the reg-stack, i.e., the stack is one deeper after the asm than it was before. But, it is possible that reload will think that it can use the same reg for both the input and the output, if input B dies in this insn.
If any input operand uses the f constraint, all output reg
constraints must use the & earlyclobber.
The asm above would be written as
asm ("foo" : "=&t" (a) : "f" (b));
Output operands must specifically indicate which reg an output
appears in after an asm. =f is not allowed: the operand
constraints must select a class with a single reg.
Output operands must start at the top of the reg-stack: output operands may not “skip” a reg.
Here are a couple of reasonable asms to want to write. This asm takes one input, which is internally popped, and produces two outputs.
asm ("fsincos" : "=t" (cos), "=u" (sin) : "0" (inp));
This asm takes two inputs, which are popped by the fyl2xp1 opcode,
and replaces them with one output. The user must code the st(1)
clobber for reg-stack.c to know that fyl2xp1 pops both inputs.
asm ("fyl2xp1" : "=t" (result) : "0" (x), "u" (y) : "st(1)");
asm Operands
Here are specific details on what constraint letters you can use with
asm operands.
Constraints can say whether
an operand may be in a register, and which kinds of register; whether the
operand can be a memory reference, and which kinds of address; whether the
operand may be an immediate constant, and which possible values it may
have. Constraints can also require two operands to match.
Side-effects aren't allowed in operands of inline asm, unless
‘<’ or ‘>’ constraints are used, because there is no guarantee
that the side-effects will happen exactly once in an instruction that can update
the addressing register.
The simplest kind of constraint is a string full of letters, each of which describes one kind of operand that is permitted. Here are the letters that are allowed:
TARGET_MEM_CONSTRAINT macro.
For example, an address which is constant is offsettable; so is an address that is the sum of a register and a constant (as long as a slightly larger constant is also within the range of address-offsets supported by the machine); but an autoincrement or autodecrement address is not offsettable. More complicated indirect/indexed addresses may or may not be offsettable depending on the other addressing modes that the machine supports.
Note that in an output operand which can be matched by another operand, the constraint letter ‘o’ is valid only when accompanied by both ‘<’ (if the target machine has predecrement addressing) and ‘>’ (if the target machine has preincrement addressing).
asm this constraint is only
allowed if the operand is used exactly once in an instruction that can
handle the side-effects. Not using an operand with ‘<’ in constraint
string in the inline asm pattern at all or using it in multiple
instructions isn't valid, because the side-effects wouldn't be performed
or would be performed more than once. Furthermore, on some targets
the operand with ‘<’ in constraint string must be accompanied by
special instruction suffixes like %U0 instruction suffix on PowerPC
or %P0 on IA-64.
asm the same restrictions
as for ‘<’ apply.
const_double) is
allowed, but only if the target floating point format is the same as
that of the host machine (on which the compiler is running).
const_double or
const_vector) is allowed.
This might appear strange; if an insn allows a constant operand with a value not known at compile time, it certainly must allow any known value. So why use ‘s’ instead of ‘i’? Sometimes it allows better code to be generated.
For example, on the 68000 in a fullword instruction it is possible to use an immediate operand; but if the immediate value is between −128 and 127, better code results from loading the value into a register and using the register. This is because the load into the register can be done with a ‘moveq’ instruction. We arrange for this to happen by defining the letter ‘K’ to mean “any integer outside the range −128 to 127”, and then specifying ‘Ks’ in the operand constraints.
This number is allowed to be more than a single digit. If multiple digits are encountered consecutively, they are interpreted as a single decimal integer. There is scant chance for ambiguity, since to-date it has never been desirable that ‘10’ be interpreted as matching either operand 1 or operand 0. Should this be desired, one can use multiple alternatives instead.
This is called a matching constraint and what it really means is
that the assembler has only a single operand that fills two roles
which asm distinguishes. For example, an add instruction uses
two input operands and an output operand, but on most CISC
machines an add instruction really has only two operands, one of them an
input-output operand:
addl #35,r12
Matching constraints are used in these circumstances. More precisely, the two operands that match must include one input-only operand and one output-only operand. Moreover, the digit must be a smaller number than the number of the operand that uses it in the constraint.
‘p’ in the constraint must be accompanied by address_operand
as the predicate in the match_operand. This predicate interprets
the mode specified in the match_operand as the mode of the memory
reference for which the address would be valid.
Sometimes a single instruction has multiple alternative sets of possible operands. For example, on the 68000, a logical-or instruction can combine register or an immediate value into memory, or it can combine any kind of operand into a register; but it cannot combine one memory location into another.
These constraints are represented as multiple alternatives. An alternative can be described by a series of letters for each operand. The overall constraint for an operand is made from the letters for this operand from the first alternative, a comma, the letters for this operand from the second alternative, a comma, and so on until the last alternative.
If all the operands fit any one alternative, the instruction is valid. Otherwise, for each alternative, the compiler counts how many instructions must be added to copy the operands so that that alternative applies. The alternative requiring the least copying is chosen. If two alternatives need the same amount of copying, the one that comes first is chosen. These choices can be altered with the ‘?’ and ‘!’ characters:
?!Here are constraint modifier characters.
When the compiler fixes up the operands to satisfy the constraints, it needs to know which operands are inputs to the instruction and which are outputs from it. ‘=’ identifies an output; ‘+’ identifies an operand that is both input and output; all other operands are assumed to be input only.
If you specify ‘=’ or ‘+’ in a constraint, you put it in the first character of the constraint string.
‘&’ applies only to the alternative in which it is written. In constraints with multiple alternatives, sometimes one alternative requires ‘&’ while others do not. See, for example, the ‘movdf’ insn of the 68000.
An input operand can be tied to an earlyclobber operand if its only use as an input occurs before the early result is written. Adding alternatives of this form often allows GCC to produce better code when only some of the inputs can be affected by the earlyclobber. See, for example, the ‘mulsi3’ insn of the ARM.
‘&’ does not obviate the need to write ‘=’.
define_peephole2
and define_splits performed after reload cannot rely on
‘%’ to make the intended insn match.
Whenever possible, you should use the general-purpose constraint letters
in asm arguments, since they will convey meaning more readily to
people reading your code. Failing that, use the constraint letters
that usually have very similar meanings across architectures. The most
commonly used constraints are ‘m’ and ‘r’ (for memory and
general-purpose registers respectively; see Simple Constraints), and
‘I’, usually the letter indicating the most common
immediate-constant format.
Each architecture defines additional constraints. These constraints
are used by the compiler itself for instruction generation, as well as
for asm statements; therefore, some of the constraints are not
particularly useful for asm. Here is a summary of some of the
machine-dependent constraints available on some particular machines;
it includes both constraints that are useful for asm and
constraints that aren't. The compiler source file mentioned in the
table heading for each architecture is the definitive reference for
the meanings of that architecture's constraints.
fwFGIJKLMQasm statements)
RSUvUyUqladwebqtxyzIJKLMNOPGQU16KLCm1Cl1Cr1Cali, except that for position independent code,
no symbols / expressions needing relocations are allowed.
CsyRcsRscRctRgsRraRccSraCfmUNSPEC_FP_MODE.
btpIJKLMNGafqxyZIJKzdepi instruction
LMNldil instruction
OPand operations in depi
and extru instructions
SUGAlo_sum data-linkage-table memory operand
QRTWkftaIJKMNObdfvwdwfwswahqclxyzIJSImode constants)
KLMNOPGHmm does not allow addresses that update the base register.
If ‘<’ or ‘>’ constraint is also used, they are allowed and
therefore on PowerPC targets in that case it is only safe
to use ‘m<>’ in an asm statement if that asm statement
accesses the operand exactly once. The asm statement must also
use ‘%U<opno>’ as a placeholder for the “update” flag in the
corresponding load or store instruction. For example:
asm ("st%U0 %1,%0" : "=m<>" (mem) : "r" (val));
is correct but:
asm ("st %1,%0" : "=m<>" (mem) : "r" (val));
is not.
esQasm statements)
Zasm statements)
Raasm statements)
STUtWjRa, b, c, d,
si, di, bp, sp).
ql. In 32-bit mode, a,
b, c, and d; in 64-bit mode, any integer register.
Qh: a, b,
c, and d.
aa register.
bb register.
cc register.
dd register.
Ssi register.
Ddi register.
Aa and d registers. This class is used for instructions
that return double word results in the ax:dx register pair. Single
word values will be allocated either in ax or dx.
For example on i386 the following implements rdtsc:
unsigned long long rdtsc (void)
{
unsigned long long tick;
__asm__ __volatile__("rdtsc":"=A"(tick));
return tick;
}
This is not correct on x86_64 as it would allocate tick in either ax
or dx. You have to use the following variant instead:
unsigned long long rdtsc (void)
{
unsigned int tickl, tickh;
__asm__ __volatile__("rdtsc":"=a"(tickl),"=d"(tickh));
return ((unsigned long long)tickh << 32)|tickl;
}
ft%st(0)).
u%st(1)).
yxYz%xmm0).
IJKL0xFF or 0xFFFF, for andsi as a zero-extending move.
Mlea instruction).
Nin and out
instructions).
GCeZar0 to r3 for addl instruction
bcdefmGIJKLMNOPdep instruction
QRshladd instruction
SaACC_REGS (acc0 to acc7).
bEVEN_ACC_REGS (acc0 to acc7).
cCC_REGS (fcc0 to fcc3 and
icc0 to icc3).
dGPR_REGS (gr0 to gr63).
eEVEN_REGS (gr0 to gr63).
Odd registers are excluded not in the class but through the use of a machine
mode larger than 4 bytes.
fFPR_REGS (fr0 to fr63).
hFEVEN_REGS (fr0 to fr63).
Odd registers are excluded not in the class but through the use of a machine
mode larger than 4 bytes.
lLR_REG (the lr register).
qQUAD_REGS (gr2 to gr63).
Register numbers not divisible by 4 are excluded not in the class but through
the use of a machine mode larger than 8 bytes.
tICC_REGS (icc0 to icc3).
uFCC_REGS (fcc0 to fcc3).
vICR_REGS (cc4 to cc7).
wFCR_REGS (cc0 to cc3).
xQUAD_FPR_REGS (fr0 to fr63).
Register numbers not divisible by 4 are excluded not in the class but through
the use of a machine mode larger than 8 bytes.
zSPR_REGS (lcr and lr).
AQUAD_ACC_REGS (acc0 to acc7).
BACCG_REGS (accg0 to accg7).
CCR_REGS (cc0 to cc7).
GIJLMNOPadzqnA, then the register P0.
DWeABbvfcCtkuxywKshKuhKs7Ku7Ku5Ks4Ks3Ku3PnPAPBM1M2JLH
QRspRfbRsbRcrRclR0wR1wR2wR3wR02R13RdiRhlR23RaaRawRalRqiRadRsiRhiRhcRraRflRmmRpiRpaIs3IS1IS2IU2In4In5In6IM2IlbIlwSdSaSiSsSfSsS1abcdemexerhjltvxyzABCDIJKLMNOSTUWYZdr0 to r31).
zrmsr, $fcc1 to $fcc7).
dr unless
generating MIPS16 code.
fhhi register. This constraint is no longer supported.
llo register. Use this register to store values that are
no bigger than a word.
xhi and lo registers. Use this register
to store doubleword values.
c$25 for -mabicalls.
v$3. Do not use this constraint in new code;
it is retained only for compatibility with glibc.
yr; retained for backwards compatibility.
zIJKLlui.
Mlui, addiu
or ori.
NOPGRadfIJKLMNOPRGSTQUWCsCiC0CjCmvqCapswCmvzCmvsApAcABWINadfGIJKLMNOQRInt3Int8JKLMNOPQbiQscWabWbcBC as a base register, with an optional offset.
WcaAX, BC, DE, or HL for the address, for calls.
WcvWd2DE as a base register, with an optional offset.
WdeDE as a base register, without any offset.
WfrWh1HL as a base register, with an optional one-byte offset.
WhbHL as a base register, with B or C as the index register.
WhlHL as a base register, without any offset.
Ws1SP as a base register, with an optional one-byte offset.
YAAX register.
BBC register.
DDE register.
RA through L registers.
SSP register.
THL register.
Z08WR8 register.
Z10WR10 register.
ZintR24 to R31).
aA register.
bB register.
cC register.
dD register.
eE register.
hH register.
lL register.
vwPSW register.
xX register.
QSymbolInt08Sint08Sint16Sint24Uint04fecdbhDIJKsethi instruction)
Lmovcc instructions
Mmovrcc instructions
NSImode
OGHQRSTUWYacdiohl instruction. const_int is treated as a 64 bit value.
ffsmbi.
ABCDiohl instruction. const_int is treated as a 32 bit value.
IJKMstop.
Niohl and fsmbi.
OPRSTUWYZiohl instruction. const_int is sign extended to 128 bit.
acdfIJKL(0..4095)(−524288..524287)MN0..9:H,Q:D,S,H:0,F:QRSTUWYdethlxqyzacbfijIJKLMNZabcdetyzIJKLMNOPQRSTUZabABCDaDbIu4Iu5In5Is5I5xIuBIsBIsCJcJsQRZR00R01R02R03R04R05R06R07R08R09R10IJKLm asm ("st_add %I0,%1,%i0" : "=m<>" (*mem) : "r" (val));
MNOPQSTUWYZ0Z1R00R01R02R03R04R05R06R07R08R09R10IJKLm asm ("swadd %I0,%1,%i0" : "=m<>" (mem) : "r" (val));
MNOPQTUWYabAIJKL
You can specify the name to be used in the assembler code for a C
function or variable by writing the asm (or __asm__)
keyword after the declarator as follows:
int foo asm ("myfoo") = 2;
This specifies that the name to be used for the variable foo in
the assembler code should be ‘myfoo’ rather than the usual
‘_foo’.
On systems where an underscore is normally prepended to the name of a C function or variable, this feature allows you to define names for the linker that do not start with an underscore.
It does not make sense to use this feature with a non-static local variable since such variables do not have assembler names. If you are trying to put the variable in a particular register, see Explicit Reg Vars. GCC presently accepts such code with a warning, but will probably be changed to issue an error, rather than a warning, in the future.
You cannot use asm in this way in a function definition; but
you can get the same effect by writing a declaration for the function
before its definition and putting asm there, like this:
extern func () asm ("FUNC");
func (x, y)
int x, y;
/* ... */
It is up to you to make sure that the assembler names you choose do not conflict with any other assembler symbols. Also, you must not use a register name; that would produce completely invalid assembler code. GCC does not as yet have the ability to store static variables in registers. Perhaps that will be added.
GNU C allows you to put a few global variables into specified hardware registers. You can also specify the register in which an ordinary register variable should be allocated.
asm statement and the asm statement itself is
not deleted. The compiler's data flow analysis is capable of determining
where the specified registers contain live values, and where they are
available for other uses. Stores into local register variables may be deleted
when they appear to be dead according to dataflow analysis. References
to local register variables may be deleted or moved or simplified.
These local variables are sometimes convenient for use with the extended
asm feature (see Extended Asm), if you want to write one
output of the assembler instruction directly into a particular register.
(This will work provided the register you specify fits the constraints
specified for that operand in the asm.)
You can define a global register variable in GNU C like this:
register int *foo asm ("a5");
Here a5 is the name of the register which should be used. Choose a
register which is normally saved and restored by function calls on your
machine, so that library routines will not clobber it.
Naturally the register name is cpu-dependent, so you would need to
conditionalize your program according to cpu type. The register
a5 would be a good choice on a 68000 for a variable of pointer
type. On machines with register windows, be sure to choose a “global”
register that is not affected magically by the function call mechanism.
In addition, operating systems on one type of cpu may differ in how they
name the registers; then you would need additional conditionals. For
example, some 68000 operating systems call this register %a5.
Eventually there may be a way of asking the compiler to choose a register automatically, but first we need to figure out how it should choose and how to enable you to guide the choice. No solution is evident.
Defining a global register variable in a certain register reserves that register entirely for this use, at least within the current compilation. The register will not be allocated for any other purpose in the functions in the current compilation. The register will not be saved and restored by these functions. Stores into this register are never deleted even if they would appear to be dead, but references may be deleted or moved or simplified.
It is not safe to access the global register variables from signal handlers, or from more than one thread of control, because the system library routines may temporarily use the register for other things (unless you recompile them specially for the task at hand).
It is not safe for one function that uses a global register variable to
call another such function foo by way of a third function
lose that was compiled without knowledge of this variable (i.e. in a
different source file in which the variable wasn't declared). This is
because lose might save the register and put some other value there.
For example, you can't expect a global register variable to be available in
the comparison-function that you pass to qsort, since qsort
might have put something else in that register. (If you are prepared to
recompile qsort with the same global register variable, you can
solve this problem.)
If you want to recompile qsort or other source files which do not
actually use your global register variable, so that they will not use that
register for any other purpose, then it suffices to specify the compiler
option -ffixed-reg. You need not actually add a global
register declaration to their source code.
A function which can alter the value of a global register variable cannot safely be called from a function compiled without this variable, because it could clobber the value the caller expects to find there on return. Therefore, the function which is the entry point into the part of the program that uses the global register variable must explicitly save and restore the value which belongs to its caller.
On most machines, longjmp will restore to each global register
variable the value it had at the time of the setjmp. On some
machines, however, longjmp will not change the value of global
register variables. To be portable, the function that called setjmp
should make other arrangements to save the values of the global register
variables, and to restore them in a longjmp. This way, the same
thing will happen regardless of what longjmp does.
All global register variable declarations must precede all function definitions. If such a declaration could appear after function definitions, the declaration would be too late to prevent the register from being used for other purposes in the preceding functions.
Global register variables may not have initial values, because an executable file has no means to supply initial contents for a register.
On the SPARC, there are reports that g3 ... g7 are suitable
registers, but certain library functions, such as getwd, as well
as the subroutines for division and remainder, modify g3 and g4. g1 and
g2 are local temporaries.
On the 68000, a2 ... a5 should be suitable, as should d2 ... d7. Of course, it will not do to use more than a few of those.
You can define a local register variable with a specified register like this:
register int *foo asm ("a5");
Here a5 is the name of the register which should be used. Note
that this is the same syntax used for defining global register
variables, but for a local variable it would appear within a function.
Naturally the register name is cpu-dependent, but this is not a problem, since specific registers are most often useful with explicit assembler instructions (see Extended Asm). Both of these things generally require that you conditionalize your program according to cpu type.
In addition, operating systems on one type of cpu may differ in how they
name the registers; then you would need additional conditionals. For
example, some 68000 operating systems call this register %a5.
Defining such a register variable does not reserve the register; it remains available for other uses in places where flow control determines the variable's value is not live.
This option does not guarantee that GCC will generate code that has
this variable in the register you specify at all times. You may not
code an explicit reference to this register in the assembler
instruction template part of an asm statement and assume it will
always refer to this variable. However, using the variable as an
asm operand guarantees that the specified register is used
for the operand.
Stores into local register variables may be deleted when they appear to be dead according to dataflow analysis. References to local register variables may be deleted or moved or simplified.
As for global register variables, it's recommended that you choose a
register which is normally saved and restored by function calls on
your machine, so that library routines will not clobber it. A common
pitfall is to initialize multiple call-clobbered registers with
arbitrary expressions, where a function call or library call for an
arithmetic operator will overwrite a register value from a previous
assignment, for example r0 below:
register int *p1 asm ("r0") = ...;
register int *p2 asm ("r1") = ...;
In those cases, a solution is to use a temporary variable for each arbitrary expression. See Example of asm with clobbered asm reg.
-ansi and the various -std options disable certain
keywords. This causes trouble when you want to use GNU C extensions, or
a general-purpose header file that should be usable by all programs,
including ISO C programs. The keywords asm, typeof and
inline are not available in programs compiled with
-ansi or -std (although inline can be used in a
program compiled with -std=c99 or -std=c11). The
ISO C99 keyword
restrict is only available when -std=gnu99 (which will
eventually be the default) or -std=c99 (or the equivalent
-std=iso9899:1999), or an option for a later standard
version, is used.
The way to solve these problems is to put ‘__’ at the beginning and
end of each problematical keyword. For example, use __asm__
instead of asm, and __inline__ instead of inline.
Other C compilers won't accept these alternative keywords; if you want to compile with another compiler, you can define the alternate keywords as macros to replace them with the customary keywords. It looks like this:
#ifndef __GNUC__
#define __asm__ asm
#endif
-pedantic and other options cause warnings for many GNU C extensions.
You can
prevent such warnings within one expression by writing
__extension__ before the expression. __extension__ has no
effect aside from this.
enum TypesYou can define an enum tag without specifying its possible values.
This results in an incomplete type, much like what you get if you write
struct foo without describing the elements. A later declaration
which does specify the possible values completes the type.
You can't allocate variables or storage using the type while it is incomplete. However, you can work with pointers to that type.
This extension may not be very useful, but it makes the handling of
enum more consistent with the way struct and union
are handled.
This extension is not supported by GNU C++.
GCC provides three magic variables which hold the name of the current
function, as a string. The first of these is __func__, which
is part of the C99 standard:
The identifier __func__ is implicitly declared by the translator
as if, immediately following the opening brace of each function
definition, the declaration
static const char __func__[] = "function-name";
appeared, where function-name is the name of the lexically-enclosing function. This name is the unadorned name of the function.
__FUNCTION__ is another name for __func__. Older
versions of GCC recognize only this name. However, it is not
standardized. For maximum portability, we recommend you use
__func__, but provide a fallback definition with the
preprocessor:
#if __STDC_VERSION__ < 199901L
# if __GNUC__ >= 2
# define __func__ __FUNCTION__
# else
# define __func__ "<unknown>"
# endif
#endif
In C, __PRETTY_FUNCTION__ is yet another name for
__func__. However, in C++, __PRETTY_FUNCTION__ contains
the type signature of the function as well as its bare name. For
example, this program:
extern "C" {
extern int printf (char *, ...);
}
class a {
public:
void sub (int i)
{
printf ("__FUNCTION__ = %s\n", __FUNCTION__);
printf ("__PRETTY_FUNCTION__ = %s\n", __PRETTY_FUNCTION__);
}
};
int
main (void)
{
a ax;
ax.sub (0);
return 0;
}
gives this output:
__FUNCTION__ = sub
__PRETTY_FUNCTION__ = void a::sub(int)
These identifiers are not preprocessor macros. In GCC 3.3 and
earlier, in C only, __FUNCTION__ and __PRETTY_FUNCTION__
were treated as string literals; they could be used to initialize
char arrays, and they could be concatenated with other string
literals. GCC 3.4 and later treat them as variables, like
__func__. In C++, __FUNCTION__ and
__PRETTY_FUNCTION__ have always been variables.
These functions may be used to get information about the callers of a function.
This function returns the return address of the current function, or of one of its callers. The level argument is number of frames to scan up the call stack. A value of
0yields the return address of the current function, a value of1yields the return address of the caller of the current function, and so forth. When inlining the expected behavior is that the function will return the address of the function that will be returned to. To work around this behavior use thenoinlinefunction attribute.The level argument must be a constant integer.
On some machines it may be impossible to determine the return address of any function other than the current one; in such cases, or when the top of the stack has been reached, this function will return
0or a random value. In addition,__builtin_frame_addressmay be used to determine if the top of the stack has been reached.Additional post-processing of the returned value may be needed, see
__builtin_extract_return_address.This function should only be used with a nonzero argument for debugging purposes.
The address as returned by
__builtin_return_addressmay have to be fed through this function to get the actual encoded address. For example, on the 31-bit S/390 platform the highest bit has to be masked out, or on SPARC platforms an offset has to be added for the true next instruction to be executed.If no fixup is needed, this function simply passes through addr.
This function does the reverse of
__builtin_extract_return_address.
This function is similar to
__builtin_return_address, but it returns the address of the function frame rather than the return address of the function. Calling__builtin_frame_addresswith a value of0yields the frame address of the current function, a value of1yields the frame address of the caller of the current function, and so forth.The frame is the area on the stack which holds local variables and saved registers. The frame address is normally the address of the first word pushed on to the stack by the function. However, the exact definition depends upon the processor and the calling convention. If the processor has a dedicated frame pointer register, and the function has a frame, then
__builtin_frame_addresswill return the value of the frame pointer register.On some machines it may be impossible to determine the frame address of any function other than the current one; in such cases, or when the top of the stack has been reached, this function will return
0if the first frame pointer is properly initialized by the startup code.This function should only be used with a nonzero argument for debugging purposes.
On some targets, the instruction set contains SIMD vector instructions that operate on multiple values contained in one large register at the same time. For example, on the i386 the MMX, 3DNow! and SSE extensions can be used this way.
The first step in using these extensions is to provide the necessary data
types. This should be done using an appropriate typedef:
typedef int v4si __attribute__ ((vector_size (16)));
The int type specifies the base type, while the attribute specifies
the vector size for the variable, measured in bytes. For example, the
declaration above causes the compiler to set the mode for the v4si
type to be 16 bytes wide and divided into int sized units. For
a 32-bit int this means a vector of 4 units of 4 bytes, and the
corresponding mode of foo will be V4SI.
The vector_size attribute is only applicable to integral and
float scalars, although arrays, pointers, and function return values
are allowed in conjunction with this construct.
All the basic integer types can be used as base types, both as signed
and as unsigned: char, short, int, long,
long long. In addition, float and double can be
used to build floating-point vector types.
Specifying a combination that is not valid for the current architecture
will cause GCC to synthesize the instructions using a narrower mode.
For example, if you specify a variable of type V4SI and your
architecture does not allow for this specific SIMD type, GCC will
produce code that uses 4 SIs.
The types defined in this manner can be used with a subset of normal C
operations. Currently, GCC will allow using the following operators
on these types: +, -, *, /, unary minus, ^, |, &, ~, %.
The operations behave like C++ valarrays. Addition is defined as
the addition of the corresponding elements of the operands. For
example, in the code below, each of the 4 elements in a will be
added to the corresponding 4 elements in b and the resulting
vector will be stored in c.
typedef int v4si __attribute__ ((vector_size (16)));
v4si a, b, c;
c = a + b;
Subtraction, multiplication, division, and the logical operations operate in a similar manner. Likewise, the result of using the unary minus or complement operators on a vector type is a vector whose elements are the negative or complemented values of the corresponding elements in the operand.
In C it is possible to use shifting operators <<, >> on
integer-type vectors. The operation is defined as following: {a0,
a1, ..., an} >> {b0, b1, ..., bn} == {a0 >> b0, a1 >> b1,
..., an >> bn}. Vector operands must have the same number of
elements.
For the convenience in C it is allowed to use a binary vector operation where one operand is a scalar. In that case the compiler will transform the scalar operand into a vector where each element is the scalar from the operation. The transformation will happen only if the scalar could be safely converted to the vector-element type. Consider the following code.
typedef int v4si __attribute__ ((vector_size (16)));
v4si a, b, c;
long l;
a = b + 1; /* a = b + {1,1,1,1}; */
a = 2 * b; /* a = {2,2,2,2} * b; */
a = l + a; /* Error, cannot convert long to int. */
In C vectors can be subscripted as if the vector were an array with the same number of elements and base type. Out of bound accesses invoke undefined behavior at runtime. Warnings for out of bound accesses for vector subscription can be enabled with -Warray-bounds.
In GNU C vector comparison is supported within standard comparison
operators: ==, !=, <, <=, >, >=. Comparison operands can be
vector expressions of integer-type or real-type. Comparison between
integer-type vectors and real-type vectors are not supported. The
result of the comparison is a vector of the same width and number of
elements as the comparison operands with a signed integral element
type.
Vectors are compared element-wise producing 0 when comparison is false and -1 (constant of the appropriate type where all bits are set) otherwise. Consider the following example.
typedef int v4si __attribute__ ((vector_size (16)));
v4si a = {1,2,3,4};
v4si b = {3,2,1,4};
v4si c;
c = a > b; /* The result would be {0, 0,-1, 0} */
c = a == b; /* The result would be {0,-1, 0,-1} */
Vector shuffling is available using functions
__builtin_shuffle (vec, mask) and
__builtin_shuffle (vec0, vec1, mask).
Both functions construct a permutation of elements from one or two
vectors and return a vector of the same type as the input vector(s).
The mask is an integral vector with the same width (W)
and element count (N) as the output vector.
The elements of the input vectors are numbered in memory ordering of vec0 beginning at 0 and vec1 beginning at N. The elements of mask are considered modulo N in the single-operand case and modulo 2*N in the two-operand case.
Consider the following example,
typedef int v4si __attribute__ ((vector_size (16)));
v4si a = {1,2,3,4};
v4si b = {5,6,7,8};
v4si mask1 = {0,1,1,3};
v4si mask2 = {0,4,2,5};
v4si res;
res = __builtin_shuffle (a, mask1); /* res is {1,2,2,4} */
res = __builtin_shuffle (a, b, mask2); /* res is {1,5,3,6} */
Note that __builtin_shuffle is intentionally semantically
compatible with the OpenCL shuffle and shuffle2 functions.
You can declare variables and use them in function calls and returns, as well as in assignments and some casts. You can specify a vector type as a return type for a function. Vector types can also be used as function arguments. It is possible to cast from one vector type to another, provided they are of the same size (in fact, you can also cast vectors to and from other datatypes of the same size).
You cannot operate between vectors of different lengths or different signedness without a cast.
GCC implements for both C and C++ a syntactic extension to implement
the offsetof macro.
primary:
"__builtin_offsetof" "(" typename "," offsetof_member_designator ")"
offsetof_member_designator:
identifier
| offsetof_member_designator "." identifier
| offsetof_member_designator "[" expr "]"
This extension is sufficient such that
#define offsetof(type, member) __builtin_offsetof (type, member)
is a suitable definition of the offsetof macro. In C++, type
may be dependent. In either case, member may consist of a single
identifier, or a sequence of member accesses and array references.
The following builtins are intended to be compatible with those described in the Intel Itanium Processor-specific Application Binary Interface, section 7.4. As such, they depart from the normal GCC practice of using the “__builtin_” prefix, and further that they are overloaded such that they work on multiple types.
The definition given in the Intel documentation allows only for the use of
the types int, long, long long as well as their unsigned
counterparts. GCC will allow any integral scalar or pointer type that is
1, 2, 4 or 8 bytes in length.
Not all operations are supported by all target processors. If a particular operation cannot be implemented on the target processor, a warning will be generated and a call an external function will be generated. The external function will carry the same name as the builtin, with an additional suffix ‘_n’ where n is the size of the data type.
In most cases, these builtins are considered a full barrier. That is, no memory operand will be moved across the operation, either forward or backward. Further, instructions will be issued as necessary to prevent the processor from speculating loads across the operation and from queuing stores after the operation.
All of the routines are described in the Intel documentation to take “an optional list of variables protected by the memory barrier”. It's not clear what is meant by that; it could mean that only the following variables are protected, or it could mean that these variables should in addition be protected. At present GCC ignores this list and protects all variables which are globally accessible. If in the future we make some use of this list, an empty list will continue to mean all globally accessible variables.
__sync_fetch_and_add (type *ptr, type value, ...) __sync_fetch_and_sub (type *ptr, type value, ...) __sync_fetch_and_or (type *ptr, type value, ...) __sync_fetch_and_and (type *ptr, type value, ...) __sync_fetch_and_xor (type *ptr, type value, ...) __sync_fetch_and_nand (type *ptr, type value, ...) { tmp = *ptr; *ptr op= value; return tmp; }
{ tmp = *ptr; *ptr = ~(tmp & value); return tmp; } // nand
Note: GCC 4.4 and later implement __sync_fetch_and_nand
builtin as *ptr = ~(tmp & value) instead of *ptr = ~tmp & value.
__sync_add_and_fetch (type *ptr, type value, ...) __sync_sub_and_fetch (type *ptr, type value, ...) __sync_or_and_fetch (type *ptr, type value, ...) __sync_and_and_fetch (type *ptr, type value, ...) __sync_xor_and_fetch (type *ptr, type value, ...) __sync_nand_and_fetch (type *ptr, type value, ...) { *ptr op= value; return *ptr; }
{ *ptr = ~(*ptr & value); return *ptr; } // nand
Note: GCC 4.4 and later implement __sync_nand_and_fetch
builtin as *ptr = ~(*ptr & value) instead of
*ptr = ~*ptr & value.
bool __sync_bool_compare_and_swap (type *ptr, type oldval, type newval, ...) __sync_val_compare_and_swap (type *ptr, type oldval, type newval, ...)*ptr is oldval, then write newval into
*ptr.
The “bool” version returns true if the comparison is successful and
newval was written. The “val” version returns the contents
of *ptr before the operation.
__sync_synchronize (...) __sync_lock_test_and_set (type *ptr, type value, ...)*ptr, and returns the previous contents of
*ptr.
Many targets have only minimal support for such locks, and do not support
a full exchange operation. In this case, a target may support reduced
functionality here by which the only valid value to store is the
immediate constant 1. The exact value actually stored in *ptr
is implementation defined.
This builtin is not a full barrier, but rather an acquire barrier.
This means that references after the builtin cannot move to (or be
speculated to) before the builtin, but previous memory stores may not
be globally visible yet, and previous memory loads may not yet be
satisfied.
void __sync_lock_release (type *ptr, ...)__sync_lock_test_and_set.
Normally this means writing the constant 0 to *ptr.
This builtin is not a full barrier, but rather a release barrier. This means that all previous memory stores are globally visible, and all previous memory loads have been satisfied, but following memory reads are not prevented from being speculated to before the barrier.
The following built-in functions approximately match the requirements for C++11 memory model. Many are similar to the ‘__sync’ prefixed built-in functions, but all also have a memory model parameter. These are all identified by being prefixed with ‘__atomic’, and most are overloaded such that they work with multiple types.
GCC will allow any integral scalar or pointer type that is 1, 2, 4, or 8 bytes in length. 16-byte integral types are also allowed if ‘__int128’ (see __int128) is supported by the architecture.
Target architectures are encouraged to provide their own patterns for each of these built-in functions. If no target is provided, the original non-memory model set of ‘__sync’ atomic built-in functions will be utilized, along with any required synchronization fences surrounding it in order to achieve the proper behaviour. Execution in this case is subject to the same restrictions as those built-in functions.
If there is no pattern or mechanism to provide a lock free instruction sequence, a call is made to an external routine with the same parameters to be resolved at runtime.
The four non-arithmetic functions (load, store, exchange, and compare_exchange) all have a generic version as well. This generic version will work on any data type. If the data type size maps to one of the integral sizes which may have lock free support, the generic version will utilize the lock free built-in function. Otherwise an external call is left to be resolved at runtime. This external call will be the same format with the addition of a ‘size_t’ parameter inserted as the first parameter indicating the size of the object being pointed to. All objects must be the same size.
There are 6 different memory models which can be specified. These map to the same names in the C++11 standard. Refer there or to the GCC wiki on atomic synchronization for more detailed definitions. These memory models integrate both barriers to code motion as well as synchronization requirements with other threads. These are listed in approximately ascending order of strength.
__ATOMIC_RELAXED__ATOMIC_CONSUME__ATOMIC_ACQUIRE__ATOMIC_RELEASE__ATOMIC_ACQ_REL__ATOMIC_SEQ_CSTWhen implementing patterns for these built-in functions , the memory model
parameter can be ignored as long as the pattern implements the most
restrictive __ATOMIC_SEQ_CST model. Any of the other memory models
will execute correctly with this memory model but they may not execute as
efficiently as they could with a more appropriate implemention of the
relaxed requirements.
Note that the C++11 standard allows for the memory model parameter to be
determined at runtime rather than at compile time. These built-in
functions will map any runtime value to __ATOMIC_SEQ_CST rather
than invoke a runtime library call or inline a switch statement. This is
standard compliant, safe, and the simplest approach for now.
The memory model parameter is a signed int, but only the lower 8 bits are reserved for the memory model. The remainder of the signed int is reserved for future use and should be 0. Use of the predefined atomic values will ensure proper usage.
This built-in function implements an atomic load operation. It returns the contents of
*ptr.The valid memory model variants are
__ATOMIC_RELAXED,__ATOMIC_SEQ_CST,__ATOMIC_ACQUIRE, and__ATOMIC_CONSUME.
This is the generic version of an atomic load. It will return the contents of
*ptr in*ret.
This built-in function implements an atomic store operation. It writes val into
*ptr.The valid memory model variants are
__ATOMIC_RELAXED,__ATOMIC_SEQ_CST, and__ATOMIC_RELEASE.
This is the generic version of an atomic store. It will store the value of
*val into*ptr.
This built-in function implements an atomic exchange operation. It writes val into
*ptr, and returns the previous contents of*ptr.The valid memory model variants are
__ATOMIC_RELAXED,__ATOMIC_SEQ_CST,__ATOMIC_ACQUIRE,__ATOMIC_RELEASE, and__ATOMIC_ACQ_REL.
This is the generic version of an atomic exchange. It will store the contents of
*val into*ptr. The original value of*ptr will be copied into*ret.
This built-in function implements an atomic compare and exchange operation. This compares the contents of
*ptr with the contents of*expected and if equal, writes desired into*ptr. If they are not equal, the current contents of*ptr is written into*expected. weak is true for weak compare_exchange, and false for the strong variation. Many targets only offer the strong variation and ignore the parameter. When in doubt, use the strong variation.True is returned if desired is written into
*ptr and the execution is considered to conform to the memory model specified by success_memmodel. There are no restrictions on what memory model can be used here.False is returned otherwise, and the execution is considered to conform to failure_memmodel. This memory model cannot be
__ATOMIC_RELEASEnor__ATOMIC_ACQ_REL. It also cannot be a stronger model than that specified by success_memmodel.
This built-in function implements the generic version of
__atomic_compare_exchange. The function is virtually identical to__atomic_compare_exchange_n, except the desired value is also a pointer.
These built-in functions perform the operation suggested by the name, and return the result of the operation. That is,
{ *ptr op= val; return *ptr; }All memory models are valid.
These built-in functions perform the operation suggested by the name, and return the value that had previously been in
*ptr. That is,{ tmp = *ptr; *ptr op= val; return tmp; }All memory models are valid.
This built-in function performs an atomic test-and-set operation on the byte at
*ptr. The byte is set to some implementation defined non-zero "set" value and the return value istrueif and only if the previous contents were "set".All memory models are valid.
This built-in function performs an atomic clear operation on
*ptr. After the operation,*ptr will contain 0.The valid memory model variants are
__ATOMIC_RELAXED,__ATOMIC_SEQ_CST, and__ATOMIC_RELEASE.
This built-in function acts as a synchronization fence between threads based on the specified memory model.
All memory orders are valid.
This built-in function acts as a synchronization fence between a thread and signal handlers based in the same thread.
All memory orders are valid.
This built-in function returns true if objects of size bytes will always generate lock free atomic instructions for the target architecture. size must resolve to a compile time constant and the result also resolves to compile time constant.
ptr is an optional pointer to the object which may be used to determine alignment. A value of 0 indicates typical alignment should be used. The compiler may also ignore this parameter.
if (_atomic_always_lock_free (sizeof (long long), 0))
This built-in function returns true if objects of size bytes will always generate lock free atomic instructions for the target architecture. If it is not known to be lock free a call is made to a runtime routine named
__atomic_is_lock_free.ptr is an optional pointer to the object which may be used to determine alignment. A value of 0 indicates typical alignment should be used. The compiler may also ignore this parameter.
GCC implements a limited buffer overflow protection mechanism that can prevent some buffer overflow attacks.
is a built-in construct that returns a constant number of bytes from ptr to the end of the object ptr pointer points to (if known at compile time).
__builtin_object_sizenever evaluates its arguments for side-effects. If there are any side-effects in them, it returns(size_t) -1for type 0 or 1 and(size_t) 0for type 2 or 3. If there are multiple objects ptr can point to and all of them are known at compile time, the returned number is the maximum of remaining byte counts in those objects if type & 2 is 0 and minimum if nonzero. If it is not possible to determine which objects ptr points to at compile time,__builtin_object_sizeshould return(size_t) -1for type 0 or 1 and(size_t) 0for type 2 or 3.type is an integer constant from 0 to 3. If the least significant bit is clear, objects are whole variables, if it is set, a closest surrounding subobject is considered the object a pointer points to. The second bit determines if maximum or minimum of remaining bytes is computed.
struct V { char buf1[10]; int b; char buf2[10]; } var; char *p = &var.buf1[1], *q = &var.b; /* Here the object p points to is var. */ assert (__builtin_object_size (p, 0) == sizeof (var) - 1); /* The subobject p points to is var.buf1. */ assert (__builtin_object_size (p, 1) == sizeof (var.buf1) - 1); /* The object q points to is var. */ assert (__builtin_object_size (q, 0) == (char *) (&var + 1) - (char *) &var.b); /* The subobject q points to is var.b. */ assert (__builtin_object_size (q, 1) == sizeof (var.b));
There are built-in functions added for many common string operation
functions, e.g., for memcpy __builtin___memcpy_chk
built-in is provided. This built-in has an additional last argument,
which is the number of bytes remaining in object the dest
argument points to or (size_t) -1 if the size is not known.
The built-in functions are optimized into the normal string functions
like memcpy if the last argument is (size_t) -1 or if
it is known at compile time that the destination object will not
be overflown. If the compiler can determine at compile time the
object will be always overflown, it issues a warning.
The intended use can be e.g.
#undef memcpy
#define bos0(dest) __builtin_object_size (dest, 0)
#define memcpy(dest, src, n) \
__builtin___memcpy_chk (dest, src, n, bos0 (dest))
char *volatile p;
char buf[10];
/* It is unknown what object p points to, so this is optimized
into plain memcpy - no checking is possible. */
memcpy (p, "abcde", n);
/* Destination is known and length too. It is known at compile
time there will be no overflow. */
memcpy (&buf[5], "abcde", 5);
/* Destination is known, but the length is not known at compile time.
This will result in __memcpy_chk call that can check for overflow
at runtime. */
memcpy (&buf[5], "abcde", n);
/* Destination is known and it is known at compile time there will
be overflow. There will be a warning and __memcpy_chk call that
will abort the program at runtime. */
memcpy (&buf[6], "abcde", 5);
Such built-in functions are provided for memcpy, mempcpy,
memmove, memset, strcpy, stpcpy, strncpy,
strcat and strncat.
There are also checking built-in functions for formatted output functions.
int __builtin___sprintf_chk (char *s, int flag, size_t os, const char *fmt, ...);
int __builtin___snprintf_chk (char *s, size_t maxlen, int flag, size_t os,
const char *fmt, ...);
int __builtin___vsprintf_chk (char *s, int flag, size_t os, const char *fmt,
va_list ap);
int __builtin___vsnprintf_chk (char *s, size_t maxlen, int flag, size_t os,
const char *fmt, va_list ap);
The added flag argument is passed unchanged to __sprintf_chk
etc. functions and can contain implementation specific flags on what
additional security measures the checking function might take, such as
handling %n differently.
The os argument is the object size s points to, like in the
other built-in functions. There is a small difference in the behavior
though, if os is (size_t) -1, the built-in functions are
optimized into the non-checking functions only if flag is 0, otherwise
the checking function is called with os argument set to
(size_t) -1.
In addition to this, there are checking built-in functions
__builtin___printf_chk, __builtin___vprintf_chk,
__builtin___fprintf_chk and __builtin___vfprintf_chk.
These have just one additional argument, flag, right before
format string fmt. If the compiler is able to optimize them to
fputc etc. functions, it will, otherwise the checking function
should be called and the flag argument passed to it.
GCC provides a large number of built-in functions other than the ones mentioned above. Some of these are for internal use in the processing of exceptions or variable-length argument lists and will not be documented here because they may change from time to time; we do not recommend general use of these functions.
The remaining functions are provided for optimization purposes.
GCC includes built-in versions of many of the functions in the standard
C library. The versions prefixed with __builtin_ will always be
treated as having the same meaning as the C library function even if you
specify the -fno-builtin option. (see C Dialect Options)
Many of these functions are only optimized in certain cases; if they are
not optimized in a particular case, a call to the library function will
be emitted.
Outside strict ISO C mode (-ansi, -std=c90,
-std=c99 or -std=c11), the functions
_exit, alloca, bcmp, bzero,
dcgettext, dgettext, dremf, dreml,
drem, exp10f, exp10l, exp10, ffsll,
ffsl, ffs, fprintf_unlocked,
fputs_unlocked, gammaf, gammal, gamma,
gammaf_r, gammal_r, gamma_r, gettext,
index, isascii, j0f, j0l, j0,
j1f, j1l, j1, jnf, jnl, jn,
lgammaf_r, lgammal_r, lgamma_r, mempcpy,
pow10f, pow10l, pow10, printf_unlocked,
rindex, scalbf, scalbl, scalb,
signbit, signbitf, signbitl, signbitd32,
signbitd64, signbitd128, significandf,
significandl, significand, sincosf,
sincosl, sincos, stpcpy, stpncpy,
strcasecmp, strdup, strfmon, strncasecmp,
strndup, toascii, y0f, y0l, y0,
y1f, y1l, y1, ynf, ynl and
yn
may be handled as built-in functions.
All these functions have corresponding versions
prefixed with __builtin_, which may be used even in strict C90
mode.
The ISO C99 functions
_Exit, acoshf, acoshl, acosh, asinhf,
asinhl, asinh, atanhf, atanhl, atanh,
cabsf, cabsl, cabs, cacosf, cacoshf,
cacoshl, cacosh, cacosl, cacos,
cargf, cargl, carg, casinf, casinhf,
casinhl, casinh, casinl, casin,
catanf, catanhf, catanhl, catanh,
catanl, catan, cbrtf, cbrtl, cbrt,
ccosf, ccoshf, ccoshl, ccosh, ccosl,
ccos, cexpf, cexpl, cexp, cimagf,
cimagl, cimag, clogf, clogl, clog,
conjf, conjl, conj, copysignf, copysignl,
copysign, cpowf, cpowl, cpow, cprojf,
cprojl, cproj, crealf, creall, creal,
csinf, csinhf, csinhl, csinh, csinl,
csin, csqrtf, csqrtl, csqrt, ctanf,
ctanhf, ctanhl, ctanh, ctanl, ctan,
erfcf, erfcl, erfc, erff, erfl,
erf, exp2f, exp2l, exp2, expm1f,
expm1l, expm1, fdimf, fdiml, fdim,
fmaf, fmal, fmaxf, fmaxl, fmax,
fma, fminf, fminl, fmin, hypotf,
hypotl, hypot, ilogbf, ilogbl, ilogb,
imaxabs, isblank, iswblank, lgammaf,
lgammal, lgamma, llabs, llrintf, llrintl,
llrint, llroundf, llroundl, llround,
log1pf, log1pl, log1p, log2f, log2l,
log2, logbf, logbl, logb, lrintf,
lrintl, lrint, lroundf, lroundl,
lround, nearbyintf, nearbyintl, nearbyint,
nextafterf, nextafterl, nextafter,
nexttowardf, nexttowardl, nexttoward,
remainderf, remainderl, remainder, remquof,
remquol, remquo, rintf, rintl, rint,
roundf, roundl, round, scalblnf,
scalblnl, scalbln, scalbnf, scalbnl,
scalbn, snprintf, tgammaf, tgammal,
tgamma, truncf, truncl, trunc,
vfscanf, vscanf, vsnprintf and vsscanf
are handled as built-in functions
except in strict ISO C90 mode (-ansi or -std=c90).
There are also built-in versions of the ISO C99 functions
acosf, acosl, asinf, asinl, atan2f,
atan2l, atanf, atanl, ceilf, ceill,
cosf, coshf, coshl, cosl, expf,
expl, fabsf, fabsl, floorf, floorl,
fmodf, fmodl, frexpf, frexpl, ldexpf,
ldexpl, log10f, log10l, logf, logl,
modfl, modf, powf, powl, sinf,
sinhf, sinhl, sinl, sqrtf, sqrtl,
tanf, tanhf, tanhl and tanl
that are recognized in any mode since ISO C90 reserves these names for
the purpose to which ISO C99 puts them. All these functions have
corresponding versions prefixed with __builtin_.
The ISO C94 functions
iswalnum, iswalpha, iswcntrl, iswdigit,
iswgraph, iswlower, iswprint, iswpunct,
iswspace, iswupper, iswxdigit, towlower and
towupper
are handled as built-in functions
except in strict ISO C90 mode (-ansi or -std=c90).
The ISO C90 functions
abort, abs, acos, asin, atan2,
atan, calloc, ceil, cosh, cos,
exit, exp, fabs, floor, fmod,
fprintf, fputs, frexp, fscanf,
isalnum, isalpha, iscntrl, isdigit,
isgraph, islower, isprint, ispunct,
isspace, isupper, isxdigit, tolower,
toupper, labs, ldexp, log10, log,
malloc, memchr, memcmp, memcpy,
memset, modf, pow, printf, putchar,
puts, scanf, sinh, sin, snprintf,
sprintf, sqrt, sscanf, strcat,
strchr, strcmp, strcpy, strcspn,
strlen, strncat, strncmp, strncpy,
strpbrk, strrchr, strspn, strstr,
tanh, tan, vfprintf, vprintf and vsprintf
are all recognized as built-in functions unless
-fno-builtin is specified (or -fno-builtin-function
is specified for an individual function). All of these functions have
corresponding versions prefixed with __builtin_.
GCC provides built-in versions of the ISO C99 floating point comparison
macros that avoid raising exceptions for unordered operands. They have
the same names as the standard macros ( isgreater,
isgreaterequal, isless, islessequal,
islessgreater, and isunordered) , with __builtin_
prefixed. We intend for a library implementor to be able to simply
#define each standard macro to its built-in equivalent.
In the same fashion, GCC provides fpclassify, isfinite,
isinf_sign and isnormal built-ins used with
__builtin_ prefixed. The isinf and isnan
builtins appear both with and without the __builtin_ prefix.
You can use the built-in function
__builtin_types_compatible_pto determine whether two types are the same.This built-in function returns 1 if the unqualified versions of the types type1 and type2 (which are types, not expressions) are compatible, 0 otherwise. The result of this built-in function can be used in integer constant expressions.
This built-in function ignores top level qualifiers (e.g.,
const,volatile). For example,intis equivalent toconst int.The type
int[]andint[5]are compatible. On the other hand,intandchar *are not compatible, even if the size of their types, on the particular architecture are the same. Also, the amount of pointer indirection is taken into account when determining similarity. Consequently,short *is not similar toshort **. Furthermore, two types that are typedefed are considered compatible if their underlying types are compatible.An
enumtype is not considered to be compatible with anotherenumtype even if both are compatible with the same integer type; this is what the C standard specifies. For example,enum {foo, bar}is not similar toenum {hot, dog}.You would typically use this function in code whose execution varies depending on the arguments' types. For example:
#define foo(x) \ ({ \ typeof (x) tmp = (x); \ if (__builtin_types_compatible_p (typeof (x), long double)) \ tmp = foo_long_double (tmp); \ else if (__builtin_types_compatible_p (typeof (x), double)) \ tmp = foo_double (tmp); \ else if (__builtin_types_compatible_p (typeof (x), float)) \ tmp = foo_float (tmp); \ else \ abort (); \ tmp; \ })Note: This construct is only available for C.
You can use the built-in function
__builtin_choose_exprto evaluate code depending on the value of a constant expression. This built-in function returns exp1 if const_exp, which is an integer constant expression, is nonzero. Otherwise it returns exp2.This built-in function is analogous to the ‘? :’ operator in C, except that the expression returned has its type unaltered by promotion rules. Also, the built-in function does not evaluate the expression that was not chosen. For example, if const_exp evaluates to true, exp2 is not evaluated even if it has side-effects.
This built-in function can return an lvalue if the chosen argument is an lvalue.
If exp1 is returned, the return type is the same as exp1's type. Similarly, if exp2 is returned, its return type is the same as exp2.
Example:
#define foo(x) \ __builtin_choose_expr ( \ __builtin_types_compatible_p (typeof (x), double), \ foo_double (x), \ __builtin_choose_expr ( \ __builtin_types_compatible_p (typeof (x), float), \ foo_float (x), \ /* The void expression results in a compile-time error \ when assigning the result to something. */ \ (void)0))Note: This construct is only available for C. Furthermore, the unused expression (exp1 or exp2 depending on the value of const_exp) may still generate syntax errors. This may change in future revisions.
The built-in function
__builtin_complexis provided for use in implementing the ISO C11 macrosCMPLXF,CMPLXandCMPLXL. real and imag must have the same type, a real binary floating-point type, and the result has the corresponding complex type with real and imaginary parts real and imag. Unlike ‘real + I * imag’, this works even when infinities, NaNs and negative zeros are involved.
You can use the built-in function
__builtin_constant_pto determine if a value is known to be constant at compile-time and hence that GCC can perform constant-folding on expressions involving that value. The argument of the function is the value to test. The function returns the integer 1 if the argument is known to be a compile-time constant and 0 if it is not known to be a compile-time constant. A return of 0 does not indicate that the value is not a constant, but merely that GCC cannot prove it is a constant with the specified value of the -O option.You would typically use this function in an embedded application where memory was a critical resource. If you have some complex calculation, you may want it to be folded if it involves constants, but need to call a function if it does not. For example:
#define Scale_Value(X) \ (__builtin_constant_p (X) \ ? ((X) * SCALE + OFFSET) : Scale (X))You may use this built-in function in either a macro or an inline function. However, if you use it in an inlined function and pass an argument of the function as the argument to the built-in, GCC will never return 1 when you call the inline function with a string constant or compound literal (see Compound Literals) and will not return 1 when you pass a constant numeric value to the inline function unless you specify the -O option.
You may also use
__builtin_constant_pin initializers for static data. For instance, you can writestatic const int table[] = { __builtin_constant_p (EXPRESSION) ? (EXPRESSION) : -1, /* ... */ };This is an acceptable initializer even if EXPRESSION is not a constant expression, including the case where
__builtin_constant_preturns 1 because EXPRESSION can be folded to a constant but EXPRESSION contains operands that would not otherwise be permitted in a static initializer (for example,0 && foo ()). GCC must be more conservative about evaluating the built-in in this case, because it has no opportunity to perform optimization.Previous versions of GCC did not accept this built-in in data initializers. The earliest version where it is completely safe is 3.0.1.
You may use
__builtin_expectto provide the compiler with branch prediction information. In general, you should prefer to use actual profile feedback for this (-fprofile-arcs), as programmers are notoriously bad at predicting how their programs actually perform. However, there are applications in which this data is hard to collect.The return value is the value of exp, which should be an integral expression. The semantics of the built-in are that it is expected that exp == c. For example:
if (__builtin_expect (x, 0)) foo ();would indicate that we do not expect to call
foo, since we expectxto be zero. Since you are limited to integral expressions for exp, you should use constructions such asif (__builtin_expect (ptr != NULL, 1)) foo (*ptr);when testing pointer or floating-point values.
This function causes the program to exit abnormally. GCC implements this function by using a target-dependent mechanism (such as intentionally executing an illegal instruction) or by calling
abort. The mechanism used may vary from release to release so you should not rely on any particular implementation.
If control flow reaches the point of the
__builtin_unreachable, the program is undefined. It is useful in situations where the compiler cannot deduce the unreachability of the code.One such case is immediately following an
asmstatement that will either never terminate, or one that transfers control elsewhere and never returns. In this example, without the__builtin_unreachable, GCC would issue a warning that control reaches the end of a non-void function. It would also generate code to return after theasm.int f (int c, int v) { if (c) { return v; } else { asm("jmp error_handler"); __builtin_unreachable (); } }Because the
asmstatement unconditionally transfers control out of the function, control will never reach the end of the function body. The__builtin_unreachableis in fact unreachable and communicates this fact to the compiler.Another use for
__builtin_unreachableis following a call a function that never returns but that is not declared__attribute__((noreturn)), as in this example:void function_that_never_returns (void); int g (int c) { if (c) { return 1; } else { function_that_never_returns (); __builtin_unreachable (); } }
This function returns its first argument, and allows the compiler to assume that the returned pointer is at least align bytes aligned. This built-in can have either two or three arguments, if it has three, the third argument should have integer type, and if it is non-zero means misalignment offset. For example:
void *x = __builtin_assume_aligned (arg, 16);means that the compiler can assume x, set to arg, is at least 16 byte aligned, while:
void *x = __builtin_assume_aligned (arg, 32, 8);means that the compiler can assume for x, set to arg, that (char *) x - 8 is 32 byte aligned.
This function is used to flush the processor's instruction cache for the region of memory between begin inclusive and end exclusive. Some targets require that the instruction cache be flushed, after modifying memory containing code, in order to obtain deterministic behavior.
If the target does not require instruction cache flushes,
__builtin___clear_cachehas no effect. Otherwise either instructions are emitted in-line to clear the instruction cache or a call to the__clear_cachefunction in libgcc is made.
This function is used to minimize cache-miss latency by moving data into a cache before it is accessed. You can insert calls to
__builtin_prefetchinto code for which you know addresses of data in memory that is likely to be accessed soon. If the target supports them, data prefetch instructions will be generated. If the prefetch is done early enough before the access then the data will be in the cache by the time it is accessed.The value of addr is the address of the memory to prefetch. There are two optional arguments, rw and locality. The value of rw is a compile-time constant one or zero; one means that the prefetch is preparing for a write to the memory address and zero, the default, means that the prefetch is preparing for a read. The value locality must be a compile-time constant integer between zero and three. A value of zero means that the data has no temporal locality, so it need not be left in the cache after the access. A value of three means that the data has a high degree of temporal locality and should be left in all levels of cache possible. Values of one and two mean, respectively, a low or moderate degree of temporal locality. The default is three.
for (i = 0; i < n; i++) { a[i] = a[i] + b[i]; __builtin_prefetch (&a[i+j], 1, 1); __builtin_prefetch (&b[i+j], 0, 1); /* ... */ }Data prefetch does not generate faults if addr is invalid, but the address expression itself must be valid. For example, a prefetch of
p->nextwill not fault ifp->nextis not a valid address, but evaluation will fault ifpis not a valid address.If the target does not support data prefetch, the address expression is evaluated if it includes side effects but no other code is generated and GCC does not issue a warning.
Returns a positive infinity, if supported by the floating-point format, else
DBL_MAX. This function is suitable for implementing the ISO C macroHUGE_VAL.
Similar to
__builtin_huge_val, except the return type isfloat.
Similar to
__builtin_huge_val, except the return type islong double.
This built-in implements the C99 fpclassify functionality. The first five int arguments should be the target library's notion of the possible FP classes and are used for return values. They must be constant values and they must appear in this order:
FP_NAN,FP_INFINITE,FP_NORMAL,FP_SUBNORMALandFP_ZERO. The ellipsis is for exactly one floating point value to classify. GCC treats the last argument as type-generic, which means it does not do default promotion from float to double.
Similar to
__builtin_huge_val, except a warning is generated if the target floating-point format does not support infinities.
Similar to
__builtin_inf, except the return type is_Decimal32.
Similar to
__builtin_inf, except the return type is_Decimal64.
Similar to
__builtin_inf, except the return type is_Decimal128.
Similar to
__builtin_inf, except the return type isfloat. This function is suitable for implementing the ISO C99 macroINFINITY.
Similar to
__builtin_inf, except the return type islong double.
Similar to
isinf, except the return value will be negative for an argument of-Inf. Note while the parameter list is an ellipsis, this function only accepts exactly one floating point argument. GCC treats this parameter as type-generic, which means it does not do default promotion from float to double.
This is an implementation of the ISO C99 function
nan.Since ISO C99 defines this function in terms of
strtod, which we do not implement, a description of the parsing is in order. The string is parsed as bystrtol; that is, the base is recognized by leading ‘0’ or ‘0x’ prefixes. The number parsed is placed in the significand such that the least significant bit of the number is at the least significant bit of the significand. The number is truncated to fit the significand field provided. The significand is forced to be a quiet NaN.This function, if given a string literal all of which would have been consumed by strtol, is evaluated early enough that it is considered a compile-time constant.
Similar to
__builtin_nan, except the return type is_Decimal32.
Similar to
__builtin_nan, except the return type is_Decimal64.
Similar to
__builtin_nan, except the return type is_Decimal128.
Similar to
__builtin_nan, except the return type isfloat.
Similar to
__builtin_nan, except the return type islong double.
Similar to
__builtin_nan, except the significand is forced to be a signaling NaN. Thenansfunction is proposed by WG14 N965.
Similar to
__builtin_nans, except the return type isfloat.
Similar to
__builtin_nans, except the return type islong double.
Returns one plus the index of the least significant 1-bit of x, or if x is zero, returns zero.
Returns the number of leading 0-bits in x, starting at the most significant bit position. If x is 0, the result is undefined.
Returns the number of trailing 0-bits in x, starting at the least significant bit position. If x is 0, the result is undefined.
Returns the number of leading redundant sign bits in x, i.e. the number of bits following the most significant bit which are identical to it. There are no special cases for 0 or other values.
Returns the parity of x, i.e. the number of 1-bits in x modulo 2.
Similar to
__builtin_ffs, except the argument type isunsigned long.
Similar to
__builtin_clz, except the argument type isunsigned long.
Similar to
__builtin_ctz, except the argument type isunsigned long.
Similar to
__builtin_clrsb, except the argument type islong.
Similar to
__builtin_popcount, except the argument type isunsigned long.
Similar to
__builtin_parity, except the argument type isunsigned long.
Similar to
__builtin_ffs, except the argument type isunsigned long long.
Similar to
__builtin_clz, except the argument type isunsigned long long.
Similar to
__builtin_ctz, except the argument type isunsigned long long.
Similar to
__builtin_clrsb, except the argument type islong long.
Similar to
__builtin_popcount, except the argument type isunsigned long long.
Similar to
__builtin_parity, except the argument type isunsigned long long.
Returns the first argument raised to the power of the second. Unlike the
powfunction no guarantees about precision and rounding are made.
Similar to
__builtin_powi, except the argument and return types arefloat.
Similar to
__builtin_powi, except the argument and return types arelong double.
Returns x with the order of the bytes reversed; for example,
0xaabbccddbecomes0xddccbbaa. Byte here always means exactly 8 bits.
Similar to
__builtin_bswap32, except the argument and return types are 64-bit.
On some target machines, GCC supports many built-in functions specific to those machines. Generally these generate calls to specific machine instructions, but allow the compiler to schedule those calls.
These built-in functions are available for the Alpha family of processors, depending on the command-line switches used.
The following built-in functions are always available. They all generate the machine instruction that is part of the name.
long __builtin_alpha_implver (void)
long __builtin_alpha_rpcc (void)
long __builtin_alpha_amask (long)
long __builtin_alpha_cmpbge (long, long)
long __builtin_alpha_extbl (long, long)
long __builtin_alpha_extwl (long, long)
long __builtin_alpha_extll (long, long)
long __builtin_alpha_extql (long, long)
long __builtin_alpha_extwh (long, long)
long __builtin_alpha_extlh (long, long)
long __builtin_alpha_extqh (long, long)
long __builtin_alpha_insbl (long, long)
long __builtin_alpha_inswl (long, long)
long __builtin_alpha_insll (long, long)
long __builtin_alpha_insql (long, long)
long __builtin_alpha_inswh (long, long)
long __builtin_alpha_inslh (long, long)
long __builtin_alpha_insqh (long, long)
long __builtin_alpha_mskbl (long, long)
long __builtin_alpha_mskwl (long, long)
long __builtin_alpha_mskll (long, long)
long __builtin_alpha_mskql (long, long)
long __builtin_alpha_mskwh (long, long)
long __builtin_alpha_msklh (long, long)
long __builtin_alpha_mskqh (long, long)
long __builtin_alpha_umulh (long, long)
long __builtin_alpha_zap (long, long)
long __builtin_alpha_zapnot (long, long)
The following built-in functions are always with -mmax
or -mcpu=cpu where cpu is pca56 or
later. They all generate the machine instruction that is part
of the name.
long __builtin_alpha_pklb (long)
long __builtin_alpha_pkwb (long)
long __builtin_alpha_unpkbl (long)
long __builtin_alpha_unpkbw (long)
long __builtin_alpha_minub8 (long, long)
long __builtin_alpha_minsb8 (long, long)
long __builtin_alpha_minuw4 (long, long)
long __builtin_alpha_minsw4 (long, long)
long __builtin_alpha_maxub8 (long, long)
long __builtin_alpha_maxsb8 (long, long)
long __builtin_alpha_maxuw4 (long, long)
long __builtin_alpha_maxsw4 (long, long)
long __builtin_alpha_perr (long, long)
The following built-in functions are always with -mcix
or -mcpu=cpu where cpu is ev67 or
later. They all generate the machine instruction that is part
of the name.
long __builtin_alpha_cttz (long)
long __builtin_alpha_ctlz (long)
long __builtin_alpha_ctpop (long)
The following builtins are available on systems that use the OSF/1
PALcode. Normally they invoke the rduniq and wruniq
PAL calls, but when invoked with -mtls-kernel, they invoke
rdval and wrval.
void *__builtin_thread_pointer (void)
void __builtin_set_thread_pointer (void *)
These built-in functions are available for the ARM family of processors when the -mcpu=iwmmxt switch is used:
typedef int v2si __attribute__ ((vector_size (8)));
typedef short v4hi __attribute__ ((vector_size (8)));
typedef char v8qi __attribute__ ((vector_size (8)));
int __builtin_arm_getwcx (int)
void __builtin_arm_setwcx (int, int)
int __builtin_arm_textrmsb (v8qi, int)
int __builtin_arm_textrmsh (v4hi, int)
int __builtin_arm_textrmsw (v2si, int)
int __builtin_arm_textrmub (v8qi, int)
int __builtin_arm_textrmuh (v4hi, int)
int __builtin_arm_textrmuw (v2si, int)
v8qi __builtin_arm_tinsrb (v8qi, int)
v4hi __builtin_arm_tinsrh (v4hi, int)
v2si __builtin_arm_tinsrw (v2si, int)
long long __builtin_arm_tmia (long long, int, int)
long long __builtin_arm_tmiabb (long long, int, int)
long long __builtin_arm_tmiabt (long long, int, int)
long long __builtin_arm_tmiaph (long long, int, int)
long long __builtin_arm_tmiatb (long long, int, int)
long long __builtin_arm_tmiatt (long long, int, int)
int __builtin_arm_tmovmskb (v8qi)
int __builtin_arm_tmovmskh (v4hi)
int __builtin_arm_tmovmskw (v2si)
long long __builtin_arm_waccb (v8qi)
long long __builtin_arm_wacch (v4hi)
long long __builtin_arm_waccw (v2si)
v8qi __builtin_arm_waddb (v8qi, v8qi)
v8qi __builtin_arm_waddbss (v8qi, v8qi)
v8qi __builtin_arm_waddbus (v8qi, v8qi)
v4hi __builtin_arm_waddh (v4hi, v4hi)
v4hi __builtin_arm_waddhss (v4hi, v4hi)
v4hi __builtin_arm_waddhus (v4hi, v4hi)
v2si __builtin_arm_waddw (v2si, v2si)
v2si __builtin_arm_waddwss (v2si, v2si)
v2si __builtin_arm_waddwus (v2si, v2si)
v8qi __builtin_arm_walign (v8qi, v8qi, int)
long long __builtin_arm_wand(long long, long long)
long long __builtin_arm_wandn (long long, long long)
v8qi __builtin_arm_wavg2b (v8qi, v8qi)
v8qi __builtin_arm_wavg2br (v8qi, v8qi)
v4hi __builtin_arm_wavg2h (v4hi, v4hi)
v4hi __builtin_arm_wavg2hr (v4hi, v4hi)
v8qi __builtin_arm_wcmpeqb (v8qi, v8qi)
v4hi __builtin_arm_wcmpeqh (v4hi, v4hi)
v2si __builtin_arm_wcmpeqw (v2si, v2si)
v8qi __builtin_arm_wcmpgtsb (v8qi, v8qi)
v4hi __builtin_arm_wcmpgtsh (v4hi, v4hi)
v2si __builtin_arm_wcmpgtsw (v2si, v2si)
v8qi __builtin_arm_wcmpgtub (v8qi, v8qi)
v4hi __builtin_arm_wcmpgtuh (v4hi, v4hi)
v2si __builtin_arm_wcmpgtuw (v2si, v2si)
long long __builtin_arm_wmacs (long long, v4hi, v4hi)
long long __builtin_arm_wmacsz (v4hi, v4hi)
long long __builtin_arm_wmacu (long long, v4hi, v4hi)
long long __builtin_arm_wmacuz (v4hi, v4hi)
v4hi __builtin_arm_wmadds (v4hi, v4hi)
v4hi __builtin_arm_wmaddu (v4hi, v4hi)
v8qi __builtin_arm_wmaxsb (v8qi, v8qi)
v4hi __builtin_arm_wmaxsh (v4hi, v4hi)
v2si __builtin_arm_wmaxsw (v2si, v2si)
v8qi __builtin_arm_wmaxub (v8qi, v8qi)
v4hi __builtin_arm_wmaxuh (v4hi, v4hi)
v2si __builtin_arm_wmaxuw (v2si, v2si)
v8qi __builtin_arm_wminsb (v8qi, v8qi)
v4hi __builtin_arm_wminsh (v4hi, v4hi)
v2si __builtin_arm_wminsw (v2si, v2si)
v8qi __builtin_arm_wminub (v8qi, v8qi)
v4hi __builtin_arm_wminuh (v4hi, v4hi)
v2si __builtin_arm_wminuw (v2si, v2si)
v4hi __builtin_arm_wmulsm (v4hi, v4hi)
v4hi __builtin_arm_wmulul (v4hi, v4hi)
v4hi __builtin_arm_wmulum (v4hi, v4hi)
long long __builtin_arm_wor (long long, long long)
v2si __builtin_arm_wpackdss (long long, long long)
v2si __builtin_arm_wpackdus (long long, long long)
v8qi __builtin_arm_wpackhss (v4hi, v4hi)
v8qi __builtin_arm_wpackhus (v4hi, v4hi)
v4hi __builtin_arm_wpackwss (v2si, v2si)
v4hi __builtin_arm_wpackwus (v2si, v2si)
long long __builtin_arm_wrord (long long, long long)
long long __builtin_arm_wrordi (long long, int)
v4hi __builtin_arm_wrorh (v4hi, long long)
v4hi __builtin_arm_wrorhi (v4hi, int)
v2si __builtin_arm_wrorw (v2si, long long)
v2si __builtin_arm_wrorwi (v2si, int)
v2si __builtin_arm_wsadb (v8qi, v8qi)
v2si __builtin_arm_wsadbz (v8qi, v8qi)
v2si __builtin_arm_wsadh (v4hi, v4hi)
v2si __builtin_arm_wsadhz (v4hi, v4hi)
v4hi __builtin_arm_wshufh (v4hi, int)
long long __builtin_arm_wslld (long long, long long)
long long __builtin_arm_wslldi (long long, int)
v4hi __builtin_arm_wsllh (v4hi, long long)
v4hi __builtin_arm_wsllhi (v4hi, int)
v2si __builtin_arm_wsllw (v2si, long long)
v2si __builtin_arm_wsllwi (v2si, int)
long long __builtin_arm_wsrad (long long, long long)
long long __builtin_arm_wsradi (long long, int)
v4hi __builtin_arm_wsrah (v4hi, long long)
v4hi __builtin_arm_wsrahi (v4hi, int)
v2si __builtin_arm_wsraw (v2si, long long)
v2si __builtin_arm_wsrawi (v2si, int)
long long __builtin_arm_wsrld (long long, long long)
long long __builtin_arm_wsrldi (long long, int)
v4hi __builtin_arm_wsrlh (v4hi, long long)
v4hi __builtin_arm_wsrlhi (v4hi, int)
v2si __builtin_arm_wsrlw (v2si, long long)
v2si __builtin_arm_wsrlwi (v2si, int)
v8qi __builtin_arm_wsubb (v8qi, v8qi)
v8qi __builtin_arm_wsubbss (v8qi, v8qi)
v8qi __builtin_arm_wsubbus (v8qi, v8qi)
v4hi __builtin_arm_wsubh (v4hi, v4hi)
v4hi __builtin_arm_wsubhss (v4hi, v4hi)
v4hi __builtin_arm_wsubhus (v4hi, v4hi)
v2si __builtin_arm_wsubw (v2si, v2si)
v2si __builtin_arm_wsubwss (v2si, v2si)
v2si __builtin_arm_wsubwus (v2si, v2si)
v4hi __builtin_arm_wunpckehsb (v8qi)
v2si __builtin_arm_wunpckehsh (v4hi)
long long __builtin_arm_wunpckehsw (v2si)
v4hi __builtin_arm_wunpckehub (v8qi)
v2si __builtin_arm_wunpckehuh (v4hi)
long long __builtin_arm_wunpckehuw (v2si)
v4hi __builtin_arm_wunpckelsb (v8qi)
v2si __builtin_arm_wunpckelsh (v4hi)
long long __builtin_arm_wunpckelsw (v2si)
v4hi __builtin_arm_wunpckelub (v8qi)
v2si __builtin_arm_wunpckeluh (v4hi)
long long __builtin_arm_wunpckeluw (v2si)
v8qi __builtin_arm_wunpckihb (v8qi, v8qi)
v4hi __builtin_arm_wunpckihh (v4hi, v4hi)
v2si __builtin_arm_wunpckihw (v2si, v2si)
v8qi __builtin_arm_wunpckilb (v8qi, v8qi)
v4hi __builtin_arm_wunpckilh (v4hi, v4hi)
v2si __builtin_arm_wunpckilw (v2si, v2si)
long long __builtin_arm_wxor (long long, long long)
long long __builtin_arm_wzero ()
These built-in intrinsics for the ARM Advanced SIMD extension are available when the -mfpu=neon switch is used:
vadd.i32 d0, d0, d0
vadd.i16 d0, d0, d0
vadd.i8 d0, d0, d0
vadd.i32 d0, d0, d0
vadd.i16 d0, d0, d0
vadd.i8 d0, d0, d0
vadd.f32 d0, d0, d0
vadd.i32 q0, q0, q0
vadd.i16 q0, q0, q0
vadd.i8 q0, q0, q0
vadd.i32 q0, q0, q0
vadd.i16 q0, q0, q0
vadd.i8 q0, q0, q0
vadd.i64 q0, q0, q0
vadd.i64 q0, q0, q0
vadd.f32 q0, q0, q0
vaddl.u32 q0, d0, d0
vaddl.u16 q0, d0, d0
vaddl.u8 q0, d0, d0
vaddl.s32 q0, d0, d0
vaddl.s16 q0, d0, d0
vaddl.s8 q0, d0, d0
vaddw.u32 q0, q0, d0
vaddw.u16 q0, q0, d0
vaddw.u8 q0, q0, d0
vaddw.s32 q0, q0, d0
vaddw.s16 q0, q0, d0
vaddw.s8 q0, q0, d0
vhadd.u32 d0, d0, d0
vhadd.u16 d0, d0, d0
vhadd.u8 d0, d0, d0
vhadd.s32 d0, d0, d0
vhadd.s16 d0, d0, d0
vhadd.s8 d0, d0, d0
vhadd.u32 q0, q0, q0
vhadd.u16 q0, q0, q0
vhadd.u8 q0, q0, q0
vhadd.s32 q0, q0, q0
vhadd.s16 q0, q0, q0
vhadd.s8 q0, q0, q0
vrhadd.u32 d0, d0, d0
vrhadd.u16 d0, d0, d0
vrhadd.u8 d0, d0, d0
vrhadd.s32 d0, d0, d0
vrhadd.s16 d0, d0, d0
vrhadd.s8 d0, d0, d0
vrhadd.u32 q0, q0, q0
vrhadd.u16 q0, q0, q0
vrhadd.u8 q0, q0, q0
vrhadd.s32 q0, q0, q0
vrhadd.s16 q0, q0, q0
vrhadd.s8 q0, q0, q0
vqadd.u32 d0, d0, d0
vqadd.u16 d0, d0, d0
vqadd.u8 d0, d0, d0
vqadd.s32 d0, d0, d0
vqadd.s16 d0, d0, d0
vqadd.s8 d0, d0, d0
vqadd.u64 d0, d0, d0
vqadd.s64 d0, d0, d0
vqadd.u32 q0, q0, q0
vqadd.u16 q0, q0, q0
vqadd.u8 q0, q0, q0
vqadd.s32 q0, q0, q0
vqadd.s16 q0, q0, q0
vqadd.s8 q0, q0, q0
vqadd.u64 q0, q0, q0
vqadd.s64 q0, q0, q0
vaddhn.i64 d0, q0, q0
vaddhn.i32 d0, q0, q0
vaddhn.i16 d0, q0, q0
vaddhn.i64 d0, q0, q0
vaddhn.i32 d0, q0, q0
vaddhn.i16 d0, q0, q0
vraddhn.i64 d0, q0, q0
vraddhn.i32 d0, q0, q0
vraddhn.i16 d0, q0, q0
vraddhn.i64 d0, q0, q0
vraddhn.i32 d0, q0, q0
vraddhn.i16 d0, q0, q0
vmul.i32 d0, d0, d0
vmul.i16 d0, d0, d0
vmul.i8 d0, d0, d0
vmul.i32 d0, d0, d0
vmul.i16 d0, d0, d0
vmul.i8 d0, d0, d0
vmul.f32 d0, d0, d0
vmul.p8 d0, d0, d0
vmul.i32 q0, q0, q0
vmul.i16 q0, q0, q0
vmul.i8 q0, q0, q0
vmul.i32 q0, q0, q0
vmul.i16 q0, q0, q0
vmul.i8 q0, q0, q0
vmul.f32 q0, q0, q0
vmul.p8 q0, q0, q0
vqdmulh.s32 d0, d0, d0
vqdmulh.s16 d0, d0, d0
vqdmulh.s32 q0, q0, q0
vqdmulh.s16 q0, q0, q0
vqrdmulh.s32 d0, d0, d0
vqrdmulh.s16 d0, d0, d0
vqrdmulh.s32 q0, q0, q0
vqrdmulh.s16 q0, q0, q0
vmull.u32 q0, d0, d0
vmull.u16 q0, d0, d0
vmull.u8 q0, d0, d0
vmull.s32 q0, d0, d0
vmull.s16 q0, d0, d0
vmull.s8 q0, d0, d0
vmull.p8 q0, d0, d0
vqdmull.s32 q0, d0, d0
vqdmull.s16 q0, d0, d0
vmla.i32 d0, d0, d0
vmla.i16 d0, d0, d0
vmla.i8 d0, d0, d0
vmla.i32 d0, d0, d0
vmla.i16 d0, d0, d0
vmla.i8 d0, d0, d0
vmla.f32 d0, d0, d0
vmla.i32 q0, q0, q0
vmla.i16 q0, q0, q0
vmla.i8 q0, q0, q0
vmla.i32 q0, q0, q0
vmla.i16 q0, q0, q0
vmla.i8 q0, q0, q0
vmla.f32 q0, q0, q0
vmlal.u32 q0, d0, d0
vmlal.u16 q0, d0, d0
vmlal.u8 q0, d0, d0
vmlal.s32 q0, d0, d0
vmlal.s16 q0, d0, d0
vmlal.s8 q0, d0, d0
vqdmlal.s32 q0, d0, d0
vqdmlal.s16 q0, d0, d0
vmls.i32 d0, d0, d0
vmls.i16 d0, d0, d0
vmls.i8 d0, d0, d0
vmls.i32 d0, d0, d0
vmls.i16 d0, d0, d0
vmls.i8 d0, d0, d0
vmls.f32 d0, d0, d0
vmls.i32 q0, q0, q0
vmls.i16 q0, q0, q0
vmls.i8 q0, q0, q0
vmls.i32 q0, q0, q0
vmls.i16 q0, q0, q0
vmls.i8 q0, q0, q0
vmls.f32 q0, q0, q0
vmlsl.u32 q0, d0, d0
vmlsl.u16 q0, d0, d0
vmlsl.u8 q0, d0, d0
vmlsl.s32 q0, d0, d0
vmlsl.s16 q0, d0, d0
vmlsl.s8 q0, d0, d0
vqdmlsl.s32 q0, d0, d0
vqdmlsl.s16 q0, d0, d0
vsub.i32 d0, d0, d0
vsub.i16 d0, d0, d0
vsub.i8 d0, d0, d0
vsub.i32 d0, d0, d0
vsub.i16 d0, d0, d0
vsub.i8 d0, d0, d0
vsub.f32 d0, d0, d0
vsub.i32 q0, q0, q0
vsub.i16 q0, q0, q0
vsub.i8 q0, q0, q0
vsub.i32 q0, q0, q0
vsub.i16 q0, q0, q0
vsub.i8 q0, q0, q0
vsub.i64 q0, q0, q0
vsub.i64 q0, q0, q0
vsub.f32 q0, q0, q0
vsubl.u32 q0, d0, d0
vsubl.u16 q0, d0, d0
vsubl.u8 q0, d0, d0
vsubl.s32 q0, d0, d0
vsubl.s16 q0, d0, d0
vsubl.s8 q0, d0, d0
vsubw.u32 q0, q0, d0
vsubw.u16 q0, q0, d0
vsubw.u8 q0, q0, d0
vsubw.s32 q0, q0, d0
vsubw.s16 q0, q0, d0
vsubw.s8 q0, q0, d0
vhsub.u32 d0, d0, d0
vhsub.u16 d0, d0, d0
vhsub.u8 d0, d0, d0
vhsub.s32 d0, d0, d0
vhsub.s16 d0, d0, d0
vhsub.s8 d0, d0, d0
vhsub.u32 q0, q0, q0
vhsub.u16 q0, q0, q0
vhsub.u8 q0, q0, q0
vhsub.s32 q0, q0, q0
vhsub.s16 q0, q0, q0
vhsub.s8 q0, q0, q0
vqsub.u32 d0, d0, d0
vqsub.u16 d0, d0, d0
vqsub.u8 d0, d0, d0
vqsub.s32 d0, d0, d0
vqsub.s16 d0, d0, d0
vqsub.s8 d0, d0, d0
vqsub.u64 d0, d0, d0
vqsub.s64 d0, d0, d0
vqsub.u32 q0, q0, q0
vqsub.u16 q0, q0, q0
vqsub.u8 q0, q0, q0
vqsub.s32 q0, q0, q0
vqsub.s16 q0, q0, q0
vqsub.s8 q0, q0, q0
vqsub.u64 q0, q0, q0
vqsub.s64 q0, q0, q0
vsubhn.i64 d0, q0, q0
vsubhn.i32 d0, q0, q0
vsubhn.i16 d0, q0, q0
vsubhn.i64 d0, q0, q0
vsubhn.i32 d0, q0, q0
vsubhn.i16 d0, q0, q0
vrsubhn.i64 d0, q0, q0
vrsubhn.i32 d0, q0, q0
vrsubhn.i16 d0, q0, q0
vrsubhn.i64 d0, q0, q0
vrsubhn.i32 d0, q0, q0
vrsubhn.i16 d0, q0, q0
vceq.i32 d0, d0, d0
vceq.i16 d0, d0, d0
vceq.i8 d0, d0, d0
vceq.i32 d0, d0, d0
vceq.i16 d0, d0, d0
vceq.i8 d0, d0, d0
vceq.f32 d0, d0, d0
vceq.i8 d0, d0, d0
vceq.i32 q0, q0, q0
vceq.i16 q0, q0, q0
vceq.i8 q0, q0, q0
vceq.i32 q0, q0, q0
vceq.i16 q0, q0, q0
vceq.i8 q0, q0, q0
vceq.f32 q0, q0, q0
vceq.i8 q0, q0, q0
vcge.u32 d0, d0, d0
vcge.u16 d0, d0, d0
vcge.u8 d0, d0, d0
vcge.s32 d0, d0, d0
vcge.s16 d0, d0, d0
vcge.s8 d0, d0, d0
vcge.f32 d0, d0, d0
vcge.u32 q0, q0, q0
vcge.u16 q0, q0, q0
vcge.u8 q0, q0, q0
vcge.s32 q0, q0, q0
vcge.s16 q0, q0, q0
vcge.s8 q0, q0, q0
vcge.f32 q0, q0, q0
vcge.u32 d0, d0, d0
vcge.u16 d0, d0, d0
vcge.u8 d0, d0, d0
vcge.s32 d0, d0, d0
vcge.s16 d0, d0, d0
vcge.s8 d0, d0, d0
vcge.f32 d0, d0, d0
vcge.u32 q0, q0, q0
vcge.u16 q0, q0, q0
vcge.u8 q0, q0, q0
vcge.s32 q0, q0, q0
vcge.s16 q0, q0, q0
vcge.s8 q0, q0, q0
vcge.f32 q0, q0, q0
vcgt.u32 d0, d0, d0
vcgt.u16 d0, d0, d0
vcgt.u8 d0, d0, d0
vcgt.s32 d0, d0, d0
vcgt.s16 d0, d0, d0
vcgt.s8 d0, d0, d0
vcgt.f32 d0, d0, d0
vcgt.u32 q0, q0, q0
vcgt.u16 q0, q0, q0
vcgt.u8 q0, q0, q0
vcgt.s32 q0, q0, q0
vcgt.s16 q0, q0, q0
vcgt.s8 q0, q0, q0
vcgt.f32 q0, q0, q0
vcgt.u32 d0, d0, d0
vcgt.u16 d0, d0, d0
vcgt.u8 d0, d0, d0
vcgt.s32 d0, d0, d0
vcgt.s16 d0, d0, d0
vcgt.s8 d0, d0, d0
vcgt.f32 d0, d0, d0
vcgt.u32 q0, q0, q0
vcgt.u16 q0, q0, q0
vcgt.u8 q0, q0, q0
vcgt.s32 q0, q0, q0
vcgt.s16 q0, q0, q0
vcgt.s8 q0, q0, q0
vcgt.f32 q0, q0, q0
vacge.f32 d0, d0, d0
vacge.f32 q0, q0, q0
vacge.f32 d0, d0, d0
vacge.f32 q0, q0, q0
vacgt.f32 d0, d0, d0
vacgt.f32 q0, q0, q0
vacgt.f32 d0, d0, d0
vacgt.f32 q0, q0, q0
vtst.32 d0, d0, d0
vtst.16 d0, d0, d0
vtst.8 d0, d0, d0
vtst.32 d0, d0, d0
vtst.16 d0, d0, d0
vtst.8 d0, d0, d0
vtst.8 d0, d0, d0
vtst.32 q0, q0, q0
vtst.16 q0, q0, q0
vtst.8 q0, q0, q0
vtst.32 q0, q0, q0
vtst.16 q0, q0, q0
vtst.8 q0, q0, q0
vtst.8 q0, q0, q0
vabd.u32 d0, d0, d0
vabd.u16 d0, d0, d0
vabd.u8 d0, d0, d0
vabd.s32 d0, d0, d0
vabd.s16 d0, d0, d0
vabd.s8 d0, d0, d0
vabd.f32 d0, d0, d0
vabd.u32 q0, q0, q0
vabd.u16 q0, q0, q0
vabd.u8 q0, q0, q0
vabd.s32 q0, q0, q0
vabd.s16 q0, q0, q0
vabd.s8 q0, q0, q0
vabd.f32 q0, q0, q0
vabdl.u32 q0, d0, d0
vabdl.u16 q0, d0, d0
vabdl.u8 q0, d0, d0
vabdl.s32 q0, d0, d0
vabdl.s16 q0, d0, d0
vabdl.s8 q0, d0, d0
vaba.u32 d0, d0, d0
vaba.u16 d0, d0, d0
vaba.u8 d0, d0, d0
vaba.s32 d0, d0, d0
vaba.s16 d0, d0, d0
vaba.s8 d0, d0, d0
vaba.u32 q0, q0, q0
vaba.u16 q0, q0, q0
vaba.u8 q0, q0, q0
vaba.s32 q0, q0, q0
vaba.s16 q0, q0, q0
vaba.s8 q0, q0, q0
vabal.u32 q0, d0, d0
vabal.u16 q0, d0, d0
vabal.u8 q0, d0, d0
vabal.s32 q0, d0, d0
vabal.s16 q0, d0, d0
vabal.s8 q0, d0, d0
vmax.u32 d0, d0, d0
vmax.u16 d0, d0, d0
vmax.u8 d0, d0, d0
vmax.s32 d0, d0, d0
vmax.s16 d0, d0, d0
vmax.s8 d0, d0, d0
vmax.f32 d0, d0, d0
vmax.u32 q0, q0, q0
vmax.u16 q0, q0, q0
vmax.u8 q0, q0, q0
vmax.s32 q0, q0, q0
vmax.s16 q0, q0, q0
vmax.s8 q0, q0, q0
vmax.f32 q0, q0, q0
vmin.u32 d0, d0, d0
vmin.u16 d0, d0, d0
vmin.u8 d0, d0, d0
vmin.s32 d0, d0, d0
vmin.s16 d0, d0, d0
vmin.s8 d0, d0, d0
vmin.f32 d0, d0, d0
vmin.u32 q0, q0, q0
vmin.u16 q0, q0, q0
vmin.u8 q0, q0, q0
vmin.s32 q0, q0, q0
vmin.s16 q0, q0, q0
vmin.s8 q0, q0, q0
vmin.f32 q0, q0, q0
vpadd.i32 d0, d0, d0
vpadd.i16 d0, d0, d0
vpadd.i8 d0, d0, d0
vpadd.i32 d0, d0, d0
vpadd.i16 d0, d0, d0
vpadd.i8 d0, d0, d0
vpadd.f32 d0, d0, d0
vpaddl.u32 d0, d0
vpaddl.u16 d0, d0
vpaddl.u8 d0, d0
vpaddl.s32 d0, d0
vpaddl.s16 d0, d0
vpaddl.s8 d0, d0
vpaddl.u32 q0, q0
vpaddl.u16 q0, q0
vpaddl.u8 q0, q0
vpaddl.s32 q0, q0
vpaddl.s16 q0, q0
vpaddl.s8 q0, q0
vpadal.u32 d0, d0
vpadal.u16 d0, d0
vpadal.u8 d0, d0
vpadal.s32 d0, d0
vpadal.s16 d0, d0
vpadal.s8 d0, d0
vpadal.u32 q0, q0
vpadal.u16 q0, q0
vpadal.u8 q0, q0
vpadal.s32 q0, q0
vpadal.s16 q0, q0
vpadal.s8 q0, q0
vpmax.u32 d0, d0, d0
vpmax.u16 d0, d0, d0
vpmax.u8 d0, d0, d0
vpmax.s32 d0, d0, d0
vpmax.s16 d0, d0, d0
vpmax.s8 d0, d0, d0
vpmax.f32 d0, d0, d0
vpmin.u32 d0, d0, d0
vpmin.u16 d0, d0, d0
vpmin.u8 d0, d0, d0
vpmin.s32 d0, d0, d0
vpmin.s16 d0, d0, d0
vpmin.s8 d0, d0, d0
vpmin.f32 d0, d0, d0
vrecps.f32 d0, d0, d0
vrecps.f32 q0, q0, q0
vrsqrts.f32 d0, d0, d0
vrsqrts.f32 q0, q0, q0
vshl.u32 d0, d0, d0
vshl.u16 d0, d0, d0
vshl.u8 d0, d0, d0
vshl.s32 d0, d0, d0
vshl.s16 d0, d0, d0
vshl.s8 d0, d0, d0
vshl.u64 d0, d0, d0
vshl.s64 d0, d0, d0
vshl.u32 q0, q0, q0
vshl.u16 q0, q0, q0
vshl.u8 q0, q0, q0
vshl.s32 q0, q0, q0
vshl.s16 q0, q0, q0
vshl.s8 q0, q0, q0
vshl.u64 q0, q0, q0
vshl.s64 q0, q0, q0
vrshl.u32 d0, d0, d0
vrshl.u16 d0, d0, d0
vrshl.u8 d0, d0, d0
vrshl.s32 d0, d0, d0
vrshl.s16 d0, d0, d0
vrshl.s8 d0, d0, d0
vrshl.u64 d0, d0, d0
vrshl.s64 d0, d0, d0
vrshl.u32 q0, q0, q0
vrshl.u16 q0, q0, q0
vrshl.u8 q0, q0, q0
vrshl.s32 q0, q0, q0
vrshl.s16 q0, q0, q0
vrshl.s8 q0, q0, q0
vrshl.u64 q0, q0, q0
vrshl.s64 q0, q0, q0
vqshl.u32 d0, d0, d0
vqshl.u16 d0, d0, d0
vqshl.u8 d0, d0, d0
vqshl.s32 d0, d0, d0
vqshl.s16 d0, d0, d0
vqshl.s8 d0, d0, d0
vqshl.u64 d0, d0, d0
vqshl.s64 d0, d0, d0
vqshl.u32 q0, q0, q0
vqshl.u16 q0, q0, q0
vqshl.u8 q0, q0, q0
vqshl.s32 q0, q0, q0
vqshl.s16 q0, q0, q0
vqshl.s8 q0, q0, q0
vqshl.u64 q0, q0, q0
vqshl.s64 q0, q0, q0
vqrshl.u32 d0, d0, d0
vqrshl.u16 d0, d0, d0
vqrshl.u8 d0, d0, d0
vqrshl.s32 d0, d0, d0
vqrshl.s16 d0, d0, d0
vqrshl.s8 d0, d0, d0
vqrshl.u64 d0, d0, d0
vqrshl.s64 d0, d0, d0
vqrshl.u32 q0, q0, q0
vqrshl.u16 q0, q0, q0
vqrshl.u8 q0, q0, q0
vqrshl.s32 q0, q0, q0
vqrshl.s16 q0, q0, q0
vqrshl.s8 q0, q0, q0
vqrshl.u64 q0, q0, q0
vqrshl.s64 q0, q0, q0
vshl.i32 d0, d0, #0
vshl.i16 d0, d0, #0
vshl.i8 d0, d0, #0
vshl.i32 d0, d0, #0
vshl.i16 d0, d0, #0
vshl.i8 d0, d0, #0
vshl.i64 d0, d0, #0
vshl.i64 d0, d0, #0
vshl.i32 q0, q0, #0
vshl.i16 q0, q0, #0
vshl.i8 q0, q0, #0
vshl.i32 q0, q0, #0
vshl.i16 q0, q0, #0
vshl.i8 q0, q0, #0
vshl.i64 q0, q0, #0
vshl.i64 q0, q0, #0
vqshl.u32 d0, d0, #0
vqshl.u16 d0, d0, #0
vqshl.u8 d0, d0, #0
vqshl.s32 d0, d0, #0
vqshl.s16 d0, d0, #0
vqshl.s8 d0, d0, #0
vqshl.u64 d0, d0, #0
vqshl.s64 d0, d0, #0
vqshl.u32 q0, q0, #0
vqshl.u16 q0, q0, #0
vqshl.u8 q0, q0, #0
vqshl.s32 q0, q0, #0
vqshl.s16 q0, q0, #0
vqshl.s8 q0, q0, #0
vqshl.u64 q0, q0, #0
vqshl.s64 q0, q0, #0
vqshlu.s64 d0, d0, #0
vqshlu.s32 d0, d0, #0
vqshlu.s16 d0, d0, #0
vqshlu.s8 d0, d0, #0
vqshlu.s64 q0, q0, #0
vqshlu.s32 q0, q0, #0
vqshlu.s16 q0, q0, #0
vqshlu.s8 q0, q0, #0
vshll.u32 q0, d0, #0
vshll.u16 q0, d0, #0
vshll.u8 q0, d0, #0
vshll.s32 q0, d0, #0
vshll.s16 q0, d0, #0
vshll.s8 q0, d0, #0
vshr.u32 d0, d0, #0
vshr.u16 d0, d0, #0
vshr.u8 d0, d0, #0
vshr.s32 d0, d0, #0
vshr.s16 d0, d0, #0
vshr.s8 d0, d0, #0
vshr.u64 d0, d0, #0
vshr.s64 d0, d0, #0
vshr.u32 q0, q0, #0
vshr.u16 q0, q0, #0
vshr.u8 q0, q0, #0
vshr.s32 q0, q0, #0
vshr.s16 q0, q0, #0
vshr.s8 q0, q0, #0
vshr.u64 q0, q0, #0
vshr.s64 q0, q0, #0
vrshr.u32 d0, d0, #0
vrshr.u16 d0, d0, #0
vrshr.u8 d0, d0, #0
vrshr.s32 d0, d0, #0
vrshr.s16 d0, d0, #0
vrshr.s8 d0, d0, #0
vrshr.u64 d0, d0, #0
vrshr.s64 d0, d0, #0
vrshr.u32 q0, q0, #0
vrshr.u16 q0, q0, #0
vrshr.u8 q0, q0, #0
vrshr.s32 q0, q0, #0
vrshr.s16 q0, q0, #0
vrshr.s8 q0, q0, #0
vrshr.u64 q0, q0, #0
vrshr.s64 q0, q0, #0
vshrn.i64 d0, q0, #0
vshrn.i32 d0, q0, #0
vshrn.i16 d0, q0, #0
vshrn.i64 d0, q0, #0
vshrn.i32 d0, q0, #0
vshrn.i16 d0, q0, #0
vrshrn.i64 d0, q0, #0
vrshrn.i32 d0, q0, #0
vrshrn.i16 d0, q0, #0
vrshrn.i64 d0, q0, #0
vrshrn.i32 d0, q0, #0
vrshrn.i16 d0, q0, #0
vqshrn.u64 d0, q0, #0
vqshrn.u32 d0, q0, #0
vqshrn.u16 d0, q0, #0
vqshrn.s64 d0, q0, #0
vqshrn.s32 d0, q0, #0
vqshrn.s16 d0, q0, #0
vqrshrn.u64 d0, q0, #0
vqrshrn.u32 d0, q0, #0
vqrshrn.u16 d0, q0, #0
vqrshrn.s64 d0, q0, #0
vqrshrn.s32 d0, q0, #0
vqrshrn.s16 d0, q0, #0
vqshrun.s64 d0, q0, #0
vqshrun.s32 d0, q0, #0
vqshrun.s16 d0, q0, #0
vqrshrun.s64 d0, q0, #0
vqrshrun.s32 d0, q0, #0
vqrshrun.s16 d0, q0, #0
vsra.u32 d0, d0, #0
vsra.u16 d0, d0, #0
vsra.u8 d0, d0, #0
vsra.s32 d0, d0, #0
vsra.s16 d0, d0, #0
vsra.s8 d0, d0, #0
vsra.u64 d0, d0, #0
vsra.s64 d0, d0, #0
vsra.u32 q0, q0, #0
vsra.u16 q0, q0, #0
vsra.u8 q0, q0, #0
vsra.s32 q0, q0, #0
vsra.s16 q0, q0, #0
vsra.s8 q0, q0, #0
vsra.u64 q0, q0, #0
vsra.s64 q0, q0, #0
vrsra.u32 d0, d0, #0
vrsra.u16 d0, d0, #0
vrsra.u8 d0, d0, #0
vrsra.s32 d0, d0, #0
vrsra.s16 d0, d0, #0
vrsra.s8 d0, d0, #0
vrsra.u64 d0, d0, #0
vrsra.s64 d0, d0, #0
vrsra.u32 q0, q0, #0
vrsra.u16 q0, q0, #0
vrsra.u8 q0, q0, #0
vrsra.s32 q0, q0, #0
vrsra.s16 q0, q0, #0
vrsra.s8 q0, q0, #0
vrsra.u64 q0, q0, #0
vrsra.s64 q0, q0, #0
vsri.32 d0, d0, #0
vsri.16 d0, d0, #0
vsri.8 d0, d0, #0
vsri.32 d0, d0, #0
vsri.16 d0, d0, #0
vsri.8 d0, d0, #0
vsri.64 d0, d0, #0
vsri.64 d0, d0, #0
vsri.16 d0, d0, #0
vsri.8 d0, d0, #0
vsri.32 q0, q0, #0
vsri.16 q0, q0, #0
vsri.8 q0, q0, #0
vsri.32 q0, q0, #0
vsri.16 q0, q0, #0
vsri.8 q0, q0, #0
vsri.64 q0, q0, #0
vsri.64 q0, q0, #0
vsri.16 q0, q0, #0
vsri.8 q0, q0, #0
vsli.32 d0, d0, #0
vsli.16 d0, d0, #0
vsli.8 d0, d0, #0
vsli.32 d0, d0, #0
vsli.16 d0, d0, #0
vsli.8 d0, d0, #0
vsli.64 d0, d0, #0
vsli.64 d0, d0, #0
vsli.16 d0, d0, #0
vsli.8 d0, d0, #0
vsli.32 q0, q0, #0
vsli.16 q0, q0, #0
vsli.8 q0, q0, #0
vsli.32 q0, q0, #0
vsli.16 q0, q0, #0
vsli.8 q0, q0, #0
vsli.64 q0, q0, #0
vsli.64 q0, q0, #0
vsli.16 q0, q0, #0
vsli.8 q0, q0, #0
vabs.f32 d0, d0
vabs.s32 d0, d0
vabs.s16 d0, d0
vabs.s8 d0, d0
vabs.f32 q0, q0
vabs.s32 q0, q0
vabs.s16 q0, q0
vabs.s8 q0, q0
vqabs.s32 d0, d0
vqabs.s16 d0, d0
vqabs.s8 d0, d0
vqabs.s32 q0, q0
vqabs.s16 q0, q0
vqabs.s8 q0, q0
vneg.f32 d0, d0
vneg.s32 d0, d0
vneg.s16 d0, d0
vneg.s8 d0, d0
vneg.f32 q0, q0
vneg.s32 q0, q0
vneg.s16 q0, q0
vneg.s8 q0, q0
vqneg.s32 d0, d0
vqneg.s16 d0, d0
vqneg.s8 d0, d0
vqneg.s32 q0, q0
vqneg.s16 q0, q0
vqneg.s8 q0, q0
vmvn d0, d0
vmvn d0, d0
vmvn d0, d0
vmvn d0, d0
vmvn d0, d0
vmvn d0, d0
vmvn d0, d0
vmvn q0, q0
vmvn q0, q0
vmvn q0, q0
vmvn q0, q0
vmvn q0, q0
vmvn q0, q0
vmvn q0, q0
vcls.s32 d0, d0
vcls.s16 d0, d0
vcls.s8 d0, d0
vcls.s32 q0, q0
vcls.s16 q0, q0
vcls.s8 q0, q0
vclz.i32 d0, d0
vclz.i16 d0, d0
vclz.i8 d0, d0
vclz.i32 d0, d0
vclz.i16 d0, d0
vclz.i8 d0, d0
vclz.i32 q0, q0
vclz.i16 q0, q0
vclz.i8 q0, q0
vclz.i32 q0, q0
vclz.i16 q0, q0
vclz.i8 q0, q0
vcnt.8 d0, d0
vcnt.8 d0, d0
vcnt.8 d0, d0
vcnt.8 q0, q0
vcnt.8 q0, q0
vcnt.8 q0, q0
vrecpe.f32 d0, d0
vrecpe.u32 d0, d0
vrecpe.f32 q0, q0
vrecpe.u32 q0, q0
vrsqrte.f32 d0, d0
vrsqrte.u32 d0, d0
vrsqrte.f32 q0, q0
vrsqrte.u32 q0, q0
vmov.32 r0, d0[0]
vmov.u16 r0, d0[0]
vmov.u8 r0, d0[0]
vmov.32 r0, d0[0]
vmov.s16 r0, d0[0]
vmov.s8 r0, d0[0]
vmov.32 r0, d0[0]
vmov.u16 r0, d0[0]
vmov.u8 r0, d0[0]
vmov.32 r0, d0[0]
vmov.u16 r0, d0[0]
vmov.u8 r0, d0[0]
vmov.32 r0, d0[0]
vmov.s16 r0, d0[0]
vmov.s8 r0, d0[0]
vmov.32 r0, d0[0]
vmov.u16 r0, d0[0]
vmov.u8 r0, d0[0]
vmov r0, r0, d0
vmov r0, r0, d0
vmov.32 d0[0], r0
vmov.16 d0[0], r0
vmov.8 d0[0], r0
vmov.32 d0[0], r0
vmov.16 d0[0], r0
vmov.8 d0[0], r0
vmov.32 d0[0], r0
vmov.16 d0[0], r0
vmov.8 d0[0], r0
vmov.32 d0[0], r0
vmov.16 d0[0], r0
vmov.8 d0[0], r0
vmov.32 d0[0], r0
vmov.16 d0[0], r0
vmov.8 d0[0], r0
vmov.32 d0[0], r0
vmov.16 d0[0], r0
vmov.8 d0[0], r0
vmov d0, r0, r0
vmov d0, r0, r0
vdup.32 d0, r0
vdup.16 d0, r0
vdup.8 d0, r0
vdup.32 d0, r0
vdup.16 d0, r0
vdup.8 d0, r0
vdup.32 d0, r0
vdup.16 d0, r0
vdup.8 d0, r0
vdup.32 q0, r0
vdup.16 q0, r0
vdup.8 q0, r0
vdup.32 q0, r0
vdup.16 q0, r0
vdup.8 q0, r0
vdup.32 q0, r0
vdup.16 q0, r0
vdup.8 q0, r0
vdup.32 d0, r0
vdup.16 d0, r0
vdup.8 d0, r0
vdup.32 d0, r0
vdup.16 d0, r0
vdup.8 d0, r0
vdup.32 d0, r0
vdup.16 d0, r0
vdup.8 d0, r0
vdup.32 q0, r0
vdup.16 q0, r0
vdup.8 q0, r0
vdup.32 q0, r0
vdup.16 q0, r0
vdup.8 q0, r0
vdup.32 q0, r0
vdup.16 q0, r0
vdup.8 q0, r0
vdup.32 d0, d0[0]
vdup.16 d0, d0[0]
vdup.8 d0, d0[0]
vdup.32 d0, d0[0]
vdup.16 d0, d0[0]
vdup.8 d0, d0[0]
vdup.32 d0, d0[0]
vdup.16 d0, d0[0]
vdup.8 d0, d0[0]
vdup.32 q0, d0[0]
vdup.16 q0, d0[0]
vdup.8 q0, d0[0]
vdup.32 q0, d0[0]
vdup.16 q0, d0[0]
vdup.8 q0, d0[0]
vdup.32 q0, d0[0]
vdup.16 q0, d0[0]
vdup.8 q0, d0[0]
vmov d0, d0
vmov d0, d0
vmov d0, d0
vmov d0, d0
vmov d0, d0
vmov d0, d0
vmov d0, d0
vmov d0, d0
vmov d0, d0
vcvt.f32.u32 d0, d0
vcvt.f32.s32 d0, d0
vcvt.u32.f32 d0, d0
vcvt.s32.f32 d0, d0
vcvt.f32.u32 q0, q0
vcvt.f32.s32 q0, q0
vcvt.u32.f32 q0, q0
vcvt.s32.f32 q0, q0
vcvt.f32.u32 d0, d0, #0
vcvt.f32.s32 d0, d0, #0
vcvt.u32.f32 d0, d0, #0
vcvt.s32.f32 d0, d0, #0
vcvt.f32.u32 q0, q0, #0
vcvt.f32.s32 q0, q0, #0
vcvt.u32.f32 q0, q0, #0
vcvt.s32.f32 q0, q0, #0
vmovn.i64 d0, q0
vmovn.i32 d0, q0
vmovn.i16 d0, q0
vmovn.i64 d0, q0
vmovn.i32 d0, q0
vmovn.i16 d0, q0
vqmovn.u64 d0, q0
vqmovn.u32 d0, q0
vqmovn.u16 d0, q0
vqmovn.s64 d0, q0
vqmovn.s32 d0, q0
vqmovn.s16 d0, q0
vqmovun.s64 d0, q0
vqmovun.s32 d0, q0
vqmovun.s16 d0, q0
vmovl.u32 q0, d0
vmovl.u16 q0, d0
vmovl.u8 q0, d0
vmovl.s32 q0, d0
vmovl.s16 q0, d0
vmovl.s8 q0, d0
vtbl.8 d0, {d0}, d0
vtbl.8 d0, {d0}, d0
vtbl.8 d0, {d0}, d0
vtbl.8 d0, {d0, d1}, d0
vtbl.8 d0, {d0, d1}, d0
vtbl.8 d0, {d0, d1}, d0
vtbl.8 d0, {d0, d1, d2}, d0
vtbl.8 d0, {d0, d1, d2}, d0
vtbl.8 d0, {d0, d1, d2}, d0
vtbl.8 d0, {d0, d1, d2, d3}, d0
vtbl.8 d0, {d0, d1, d2, d3}, d0
vtbl.8 d0, {d0, d1, d2, d3}, d0
vtbx.8 d0, {d0}, d0
vtbx.8 d0, {d0}, d0
vtbx.8 d0, {d0}, d0
vtbx.8 d0, {d0, d1}, d0
vtbx.8 d0, {d0, d1}, d0
vtbx.8 d0, {d0, d1}, d0
vtbx.8 d0, {d0, d1, d2}, d0
vtbx.8 d0, {d0, d1, d2}, d0
vtbx.8 d0, {d0, d1, d2}, d0
vtbx.8 d0, {d0, d1, d2, d3}, d0
vtbx.8 d0, {d0, d1, d2, d3}, d0
vtbx.8 d0, {d0, d1, d2, d3}, d0
vmul.f32 d0, d0, d0[0]
vmul.i32 d0, d0, d0[0]
vmul.i16 d0, d0, d0[0]
vmul.i32 d0, d0, d0[0]
vmul.i16 d0, d0, d0[0]
vmul.f32 q0, q0, d0[0]
vmul.i32 q0, q0, d0[0]
vmul.i16 q0, q0, d0[0]
vmul.i32 q0, q0, d0[0]
vmul.i16 q0, q0, d0[0]
vmull.u32 q0, d0, d0[0]
vmull.u16 q0, d0, d0[0]
vmull.s32 q0, d0, d0[0]
vmull.s16 q0, d0, d0[0]
vqdmull.s32 q0, d0, d0[0]
vqdmull.s16 q0, d0, d0[0]
vqdmulh.s32 q0, q0, d0[0]
vqdmulh.s16 q0, q0, d0[0]
vqdmulh.s32 d0, d0, d0[0]
vqdmulh.s16 d0, d0, d0[0]
vqrdmulh.s32 q0, q0, d0[0]
vqrdmulh.s16 q0, q0, d0[0]
vqrdmulh.s32 d0, d0, d0[0]
vqrdmulh.s16 d0, d0, d0[0]
vmla.f32 d0, d0, d0[0]
vmla.i32 d0, d0, d0[0]
vmla.i16 d0, d0, d0[0]
vmla.i32 d0, d0, d0[0]
vmla.i16 d0, d0, d0[0]
vmla.f32 q0, q0, d0[0]
vmla.i32 q0, q0, d0[0]
vmla.i16 q0, q0, d0[0]
vmla.i32 q0, q0, d0[0]
vmla.i16 q0, q0, d0[0]
vmlal.u32 q0, d0, d0[0]
vmlal.u16 q0, d0, d0[0]
vmlal.s32 q0, d0, d0[0]
vmlal.s16 q0, d0, d0[0]
vqdmlal.s32 q0, d0, d0[0]
vqdmlal.s16 q0, d0, d0[0]
vmls.f32 d0, d0, d0[0]
vmls.i32 d0, d0, d0[0]
vmls.i16 d0, d0, d0[0]
vmls.i32 d0, d0, d0[0]
vmls.i16 d0, d0, d0[0]
vmls.f32 q0, q0, d0[0]
vmls.i32 q0, q0, d0[0]
vmls.i16 q0, q0, d0[0]
vmls.i32 q0, q0, d0[0]
vmls.i16 q0, q0, d0[0]
vmlsl.u32 q0, d0, d0[0]
vmlsl.u16 q0, d0, d0[0]
vmlsl.s32 q0, d0, d0[0]
vmlsl.s16 q0, d0, d0[0]
vqdmlsl.s32 q0, d0, d0[0]
vqdmlsl.s16 q0, d0, d0[0]
vmul.f32 d0, d0, d0[0]
vmul.i32 d0, d0, d0[0]
vmul.i16 d0, d0, d0[0]
vmul.i32 d0, d0, d0[0]
vmul.i16 d0, d0, d0[0]
vmul.f32 q0, q0, d0[0]
vmul.i32 q0, q0, d0[0]
vmul.i16 q0, q0, d0[0]
vmul.i32 q0, q0, d0[0]
vmul.i16 q0, q0, d0[0]
vmull.u32 q0, d0, d0[0]
vmull.u16 q0, d0, d0[0]
vmull.s32 q0, d0, d0[0]
vmull.s16 q0, d0, d0[0]
vqdmull.s32 q0, d0, d0[0]
vqdmull.s16 q0, d0, d0[0]
vqdmulh.s32 q0, q0, d0[0]
vqdmulh.s16 q0, q0, d0[0]
vqdmulh.s32 d0, d0, d0[0]
vqdmulh.s16 d0, d0, d0[0]
vqrdmulh.s32 q0, q0, d0[0]
vqrdmulh.s16 q0, q0, d0[0]
vqrdmulh.s32 d0, d0, d0[0]
vqrdmulh.s16 d0, d0, d0[0]
vmla.f32 d0, d0, d0[0]
vmla.i32 d0, d0, d0[0]
vmla.i16 d0, d0, d0[0]
vmla.i32 d0, d0, d0[0]
vmla.i16 d0, d0, d0[0]
vmla.f32 q0, q0, d0[0]
vmla.i32 q0, q0, d0[0]
vmla.i16 q0, q0, d0[0]
vmla.i32 q0, q0, d0[0]
vmla.i16 q0, q0, d0[0]
vmlal.u32 q0, d0, d0[0]
vmlal.u16 q0, d0, d0[0]
vmlal.s32 q0, d0, d0[0]
vmlal.s16 q0, d0, d0[0]
vqdmlal.s32 q0, d0, d0[0]
vqdmlal.s16 q0, d0, d0[0]
vmls.f32 d0, d0, d0[0]
vmls.i32 d0, d0, d0[0]
vmls.i16 d0, d0, d0[0]
vmls.i32 d0, d0, d0[0]
vmls.i16 d0, d0, d0[0]
vmls.f32 q0, q0, d0[0]
vmls.i32 q0, q0, d0[0]
vmls.i16 q0, q0, d0[0]
vmls.i32 q0, q0, d0[0]
vmls.i16 q0, q0, d0[0]
vmlsl.u32 q0, d0, d0[0]
vmlsl.u16 q0, d0, d0[0]
vmlsl.s32 q0, d0, d0[0]
vmlsl.s16 q0, d0, d0[0]
vqdmlsl.s32 q0, d0, d0[0]
vqdmlsl.s16 q0, d0, d0[0]
vext.32 d0, d0, d0, #0
vext.16 d0, d0, d0, #0
vext.8 d0, d0, d0, #0
vext.32 d0, d0, d0, #0
vext.16 d0, d0, d0, #0
vext.8 d0, d0, d0, #0
vext.64 d0, d0, d0, #0
vext.64 d0, d0, d0, #0
vext.32 d0, d0, d0, #0
vext.16 d0, d0, d0, #0
vext.8 d0, d0, d0, #0
vext.32 q0, q0, q0, #0
vext.16 q0, q0, q0, #0
vext.8 q0, q0, q0, #0
vext.32 q0, q0, q0, #0
vext.16 q0, q0, q0, #0
vext.8 q0, q0, q0, #0
vext.64 q0, q0, q0, #0
vext.64 q0, q0, q0, #0
vext.32 q0, q0, q0, #0
vext.16 q0, q0, q0, #0
vext.8 q0, q0, q0, #0
vrev64.32 d0, d0
vrev64.16 d0, d0
vrev64.8 d0, d0
vrev64.32 d0, d0
vrev64.16 d0, d0
vrev64.8 d0, d0
vrev64.32 d0, d0
vrev64.16 d0, d0
vrev64.8 d0, d0
vrev64.32 q0, q0
vrev64.16 q0, q0
vrev64.8 q0, q0
vrev64.32 q0, q0
vrev64.16 q0, q0
vrev64.8 q0, q0
vrev64.32 q0, q0
vrev64.16 q0, q0
vrev64.8 q0, q0
vrev32.16 d0, d0
vrev32.16 d0, d0
vrev32.8 d0, d0
vrev32.8 d0, d0
vrev32.16 d0, d0
vrev32.8 d0, d0
vrev32.16 q0, q0
vrev32.16 q0, q0
vrev32.8 q0, q0
vrev32.8 q0, q0
vrev32.16 q0, q0
vrev32.8 q0, q0
vrev16.8 d0, d0
vrev16.8 d0, d0
vrev16.8 d0, d0
vrev16.8 q0, q0
vrev16.8 q0, q0
vrev16.8 q0, q0
vbsl d0, d0, d0 or vbit d0, d0, d0 or vbif d0, d0, d0
vbsl d0, d0, d0 or vbit d0, d0, d0 or vbif d0, d0, d0
vbsl d0, d0, d0 or vbit d0, d0, d0 or vbif d0, d0, d0
vbsl d0, d0, d0 or vbit d0, d0, d0 or vbif d0, d0, d0
vbsl d0, d0, d0 or vbit d0, d0, d0 or vbif d0, d0, d0
vbsl d0, d0, d0 or vbit d0, d0, d0 or vbif d0, d0, d0
vbsl d0, d0, d0 or vbit d0, d0, d0 or vbif d0, d0, d0
vbsl d0, d0, d0 or vbit d0, d0, d0 or vbif d0, d0, d0
vbsl d0, d0, d0 or vbit d0, d0, d0 or vbif d0, d0, d0
vbsl d0, d0, d0 or vbit d0, d0, d0 or vbif d0, d0, d0
vbsl d0, d0, d0 or vbit d0, d0, d0 or vbif d0, d0, d0
vbsl q0, q0, q0 or vbit q0, q0, q0 or vbif q0, q0, q0
vbsl q0, q0, q0 or vbit q0, q0, q0 or vbif q0, q0, q0
vbsl q0, q0, q0 or vbit q0, q0, q0 or vbif q0, q0, q0
vbsl q0, q0, q0 or vbit q0, q0, q0 or vbif q0, q0, q0
vbsl q0, q0, q0 or vbit q0, q0, q0 or vbif q0, q0, q0
vbsl q0, q0, q0 or vbit q0, q0, q0 or vbif q0, q0, q0
vbsl q0, q0, q0 or vbit q0, q0, q0 or vbif q0, q0, q0
vbsl q0, q0, q0 or vbit q0, q0, q0 or vbif q0, q0, q0
vbsl q0, q0, q0 or vbit q0, q0, q0 or vbif q0, q0, q0
vbsl q0, q0, q0 or vbit q0, q0, q0 or vbif q0, q0, q0
vbsl q0, q0, q0 or vbit q0, q0, q0 or vbif q0, q0, q0
vtrn.32 d0, d1
vtrn.16 d0, d1
vtrn.8 d0, d1
vtrn.32 d0, d1
vtrn.16 d0, d1
vtrn.8 d0, d1
vtrn.32 d0, d1
vtrn.16 d0, d1
vtrn.8 d0, d1
vtrn.32 q0, q1
vtrn.16 q0, q1
vtrn.8 q0, q1
vtrn.32 q0, q1
vtrn.16 q0, q1
vtrn.8 q0, q1
vtrn.32 q0, q1
vtrn.16 q0, q1
vtrn.8 q0, q1
vzip.32 d0, d1
vzip.16 d0, d1
vzip.8 d0, d1
vzip.32 d0, d1
vzip.16 d0, d1
vzip.8 d0, d1
vzip.32 d0, d1
vzip.16 d0, d1
vzip.8 d0, d1
vzip.32 q0, q1
vzip.16 q0, q1
vzip.8 q0, q1
vzip.32 q0, q1
vzip.16 q0, q1
vzip.8 q0, q1
vzip.32 q0, q1
vzip.16 q0, q1
vzip.8 q0, q1
vuzp.32 d0, d1
vuzp.16 d0, d1
vuzp.8 d0, d1
vuzp.32 d0, d1
vuzp.16 d0, d1
vuzp.8 d0, d1
vuzp.32 d0, d1
vuzp.16 d0, d1
vuzp.8 d0, d1
vuzp.32 q0, q1
vuzp.16 q0, q1
vuzp.8 q0, q1
vuzp.32 q0, q1
vuzp.16 q0, q1
vuzp.8 q0, q1
vuzp.32 q0, q1
vuzp.16 q0, q1
vuzp.8 q0, q1
vld1.32 {d0}, [r0]
vld1.16 {d0}, [r0]
vld1.8 {d0}, [r0]
vld1.32 {d0}, [r0]
vld1.16 {d0}, [r0]
vld1.8 {d0}, [r0]
vld1.64 {d0}, [r0]
vld1.64 {d0}, [r0]
vld1.32 {d0}, [r0]
vld1.16 {d0}, [r0]
vld1.8 {d0}, [r0]
vld1.32 {d0, d1}, [r0]
vld1.16 {d0, d1}, [r0]
vld1.8 {d0, d1}, [r0]
vld1.32 {d0, d1}, [r0]
vld1.16 {d0, d1}, [r0]
vld1.8 {d0, d1}, [r0]
vld1.64 {d0, d1}, [r0]
vld1.64 {d0, d1}, [r0]
vld1.32 {d0, d1}, [r0]
vld1.16 {d0, d1}, [r0]
vld1.8 {d0, d1}, [r0]
vld1.32 {d0[0]}, [r0]
vld1.16 {d0[0]}, [r0]
vld1.8 {d0[0]}, [r0]
vld1.32 {d0[0]}, [r0]
vld1.16 {d0[0]}, [r0]
vld1.8 {d0[0]}, [r0]
vld1.32 {d0[0]}, [r0]
vld1.16 {d0[0]}, [r0]
vld1.8 {d0[0]}, [r0]
vld1.64 {d0}, [r0]
vld1.64 {d0}, [r0]
vld1.32 {d0[0]}, [r0]
vld1.16 {d0[0]}, [r0]
vld1.8 {d0[0]}, [r0]
vld1.32 {d0[0]}, [r0]
vld1.16 {d0[0]}, [r0]
vld1.8 {d0[0]}, [r0]
vld1.32 {d0[0]}, [r0]
vld1.16 {d0[0]}, [r0]
vld1.8 {d0[0]}, [r0]
vld1.64 {d0}, [r0]
vld1.64 {d0}, [r0]
vld1.32 {d0[]}, [r0]
vld1.16 {d0[]}, [r0]
vld1.8 {d0[]}, [r0]
vld1.32 {d0[]}, [r0]
vld1.16 {d0[]}, [r0]
vld1.8 {d0[]}, [r0]
vld1.32 {d0[]}, [r0]
vld1.16 {d0[]}, [r0]
vld1.8 {d0[]}, [r0]
vld1.64 {d0}, [r0]
vld1.64 {d0}, [r0]
vld1.32 {d0[], d1[]}, [r0]
vld1.16 {d0[], d1[]}, [r0]
vld1.8 {d0[], d1[]}, [r0]
vld1.32 {d0[], d1[]}, [r0]
vld1.16 {d0[], d1[]}, [r0]
vld1.8 {d0[], d1[]}, [r0]
vld1.32 {d0[], d1[]}, [r0]
vld1.16 {d0[], d1[]}, [r0]
vld1.8 {d0[], d1[]}, [r0]
vld1.64 {d0, d1}, [r0]
vld1.64 {d0, d1}, [r0]
vst1.32 {d0}, [r0]
vst1.16 {d0}, [r0]
vst1.8 {d0}, [r0]
vst1.32 {d0}, [r0]
vst1.16 {d0}, [r0]
vst1.8 {d0}, [r0]
vst1.64 {d0}, [r0]
vst1.64 {d0}, [r0]
vst1.32 {d0}, [r0]
vst1.16 {d0}, [r0]
vst1.8 {d0}, [r0]
vst1.32 {d0, d1}, [r0]
vst1.16 {d0, d1}, [r0]
vst1.8 {d0, d1}, [r0]
vst1.32 {d0, d1}, [r0]
vst1.16 {d0, d1}, [r0]
vst1.8 {d0, d1}, [r0]
vst1.64 {d0, d1}, [r0]
vst1.64 {d0, d1}, [r0]
vst1.32 {d0, d1}, [r0]
vst1.16 {d0, d1}, [r0]
vst1.8 {d0, d1}, [r0]
vst1.32 {d0[0]}, [r0]
vst1.16 {d0[0]}, [r0]
vst1.8 {d0[0]}, [r0]
vst1.32 {d0[0]}, [r0]
vst1.16 {d0[0]}, [r0]
vst1.8 {d0[0]}, [r0]
vst1.32 {d0[0]}, [r0]
vst1.16 {d0[0]}, [r0]
vst1.8 {d0[0]}, [r0]
vst1.64 {d0}, [r0]
vst1.64 {d0}, [r0]
vst1.32 {d0[0]}, [r0]
vst1.16 {d0[0]}, [r0]
vst1.8 {d0[0]}, [r0]
vst1.32 {d0[0]}, [r0]
vst1.16 {d0[0]}, [r0]
vst1.8 {d0[0]}, [r0]
vst1.32 {d0[0]}, [r0]
vst1.16 {d0[0]}, [r0]
vst1.8 {d0[0]}, [r0]
vst1.64 {d0}, [r0]
vst1.64 {d0}, [r0]
vld2.32 {d0, d1}, [r0]
vld2.16 {d0, d1}, [r0]
vld2.8 {d0, d1}, [r0]
vld2.32 {d0, d1}, [r0]
vld2.16 {d0, d1}, [r0]
vld2.8 {d0, d1}, [r0]
vld2.32 {d0, d1}, [r0]
vld2.16 {d0, d1}, [r0]
vld2.8 {d0, d1}, [r0]
vld1.64 {d0, d1}, [r0]
vld1.64 {d0, d1}, [r0]
vld2.32 {d0, d1}, [r0]
vld2.16 {d0, d1}, [r0]
vld2.8 {d0, d1}, [r0]
vld2.32 {d0, d1}, [r0]
vld2.16 {d0, d1}, [r0]
vld2.8 {d0, d1}, [r0]
vld2.32 {d0, d1}, [r0]
vld2.16 {d0, d1}, [r0]
vld2.8 {d0, d1}, [r0]
vld2.32 {d0[0], d1[0]}, [r0]
vld2.16 {d0[0], d1[0]}, [r0]
vld2.8 {d0[0], d1[0]}, [r0]
vld2.32 {d0[0], d1[0]}, [r0]
vld2.16 {d0[0], d1[0]}, [r0]
vld2.8 {d0[0], d1[0]}, [r0]
vld2.32 {d0[0], d1[0]}, [r0]
vld2.16 {d0[0], d1[0]}, [r0]
vld2.8 {d0[0], d1[0]}, [r0]
vld2.32 {d0[0], d1[0]}, [r0]
vld2.16 {d0[0], d1[0]}, [r0]
vld2.32 {d0[0], d1[0]}, [r0]
vld2.16 {d0[0], d1[0]}, [r0]
vld2.32 {d0[0], d1[0]}, [r0]
vld2.16 {d0[0], d1[0]}, [r0]
vld2.32 {d0[], d1[]}, [r0]
vld2.16 {d0[], d1[]}, [r0]
vld2.8 {d0[], d1[]}, [r0]
vld2.32 {d0[], d1[]}, [r0]
vld2.16 {d0[], d1[]}, [r0]
vld2.8 {d0[], d1[]}, [r0]
vld2.32 {d0[], d1[]}, [r0]
vld2.16 {d0[], d1[]}, [r0]
vld2.8 {d0[], d1[]}, [r0]
vld1.64 {d0, d1}, [r0]
vld1.64 {d0, d1}, [r0]
vst2.32 {d0, d1}, [r0]
vst2.16 {d0, d1}, [r0]
vst2.8 {d0, d1}, [r0]
vst2.32 {d0, d1}, [r0]
vst2.16 {d0, d1}, [r0]
vst2.8 {d0, d1}, [r0]
vst2.32 {d0, d1}, [r0]
vst2.16 {d0, d1}, [r0]
vst2.8 {d0, d1}, [r0]
vst1.64 {d0, d1}, [r0]
vst1.64 {d0, d1}, [r0]
vst2.32 {d0, d1}, [r0]
vst2.16 {d0, d1}, [r0]
vst2.8 {d0, d1}, [r0]
vst2.32 {d0, d1}, [r0]
vst2.16 {d0, d1}, [r0]
vst2.8 {d0, d1}, [r0]
vst2.32 {d0, d1}, [r0]
vst2.16 {d0, d1}, [r0]
vst2.8 {d0, d1}, [r0]
vst2.32 {d0[0], d1[0]}, [r0]
vst2.16 {d0[0], d1[0]}, [r0]
vst2.8 {d0[0], d1[0]}, [r0]
vst2.32 {d0[0], d1[0]}, [r0]
vst2.16 {d0[0], d1[0]}, [r0]
vst2.8 {d0[0], d1[0]}, [r0]
vst2.32 {d0[0], d1[0]}, [r0]
vst2.16 {d0[0], d1[0]}, [r0]
vst2.8 {d0[0], d1[0]}, [r0]
vst2.32 {d0[0], d1[0]}, [r0]
vst2.16 {d0[0], d1[0]}, [r0]
vst2.32 {d0[0], d1[0]}, [r0]
vst2.16 {d0[0], d1[0]}, [r0]
vst2.32 {d0[0], d1[0]}, [r0]
vst2.16 {d0[0], d1[0]}, [r0]
vld3.32 {d0, d1, d2}, [r0]
vld3.16 {d0, d1, d2}, [r0]
vld3.8 {d0, d1, d2}, [r0]
vld3.32 {d0, d1, d2}, [r0]
vld3.16 {d0, d1, d2}, [r0]
vld3.8 {d0, d1, d2}, [r0]
vld3.32 {d0, d1, d2}, [r0]
vld3.16 {d0, d1, d2}, [r0]
vld3.8 {d0, d1, d2}, [r0]
vld1.64 {d0, d1, d2}, [r0]
vld1.64 {d0, d1, d2}, [r0]
vld3.32 {d0, d1, d2}, [r0]
vld3.16 {d0, d1, d2}, [r0]
vld3.8 {d0, d1, d2}, [r0]
vld3.32 {d0, d1, d2}, [r0]
vld3.16 {d0, d1, d2}, [r0]
vld3.8 {d0, d1, d2}, [r0]
vld3.32 {d0, d1, d2}, [r0]
vld3.16 {d0, d1, d2}, [r0]
vld3.8 {d0, d1, d2}, [r0]
vld3.32 {d0[0], d1[0], d2[0]}, [r0]
vld3.16 {d0[0], d1[0], d2[0]}, [r0]
vld3.8 {d0[0], d1[0], d2[0]}, [r0]
vld3.32 {d0[0], d1[0], d2[0]}, [r0]
vld3.16 {d0[0], d1[0], d2[0]}, [r0]
vld3.8 {d0[0], d1[0], d2[0]}, [r0]
vld3.32 {d0[0], d1[0], d2[0]}, [r0]
vld3.16 {d0[0], d1[0], d2[0]}, [r0]
vld3.8 {d0[0], d1[0], d2[0]}, [r0]
vld3.32 {d0[0], d1[0], d2[0]}, [r0]
vld3.16 {d0[0], d1[0], d2[0]}, [r0]
vld3.32 {d0[0], d1[0], d2[0]}, [r0]
vld3.16 {d0[0], d1[0], d2[0]}, [r0]
vld3.32 {d0[0], d1[0], d2[0]}, [r0]
vld3.16 {d0[0], d1[0], d2[0]}, [r0]
vld3.32 {d0[], d1[], d2[]}, [r0]
vld3.16 {d0[], d1[], d2[]}, [r0]
vld3.8 {d0[], d1[], d2[]}, [r0]
vld3.32 {d0[], d1[], d2[]}, [r0]
vld3.16 {d0[], d1[], d2[]}, [r0]
vld3.8 {d0[], d1[], d2[]}, [r0]
vld3.32 {d0[], d1[], d2[]}, [r0]
vld3.16 {d0[], d1[], d2[]}, [r0]
vld3.8 {d0[], d1[], d2[]}, [r0]
vld1.64 {d0, d1, d2}, [r0]
vld1.64 {d0, d1, d2}, [r0]
vst3.32 {d0, d1, d2, d3}, [r0]
vst3.16 {d0, d1, d2, d3}, [r0]
vst3.8 {d0, d1, d2, d3}, [r0]
vst3.32 {d0, d1, d2, d3}, [r0]
vst3.16 {d0, d1, d2, d3}, [r0]
vst3.8 {d0, d1, d2, d3}, [r0]
vst3.32 {d0, d1, d2, d3}, [r0]
vst3.16 {d0, d1, d2, d3}, [r0]
vst3.8 {d0, d1, d2, d3}, [r0]
vst1.64 {d0, d1, d2, d3}, [r0]
vst1.64 {d0, d1, d2, d3}, [r0]
vst3.32 {d0, d1, d2}, [r0]
vst3.16 {d0, d1, d2}, [r0]
vst3.8 {d0, d1, d2}, [r0]
vst3.32 {d0, d1, d2}, [r0]
vst3.16 {d0, d1, d2}, [r0]
vst3.8 {d0, d1, d2}, [r0]
vst3.32 {d0, d1, d2}, [r0]
vst3.16 {d0, d1, d2}, [r0]
vst3.8 {d0, d1, d2}, [r0]
vst3.32 {d0[0], d1[0], d2[0]}, [r0]
vst3.16 {d0[0], d1[0], d2[0]}, [r0]
vst3.8 {d0[0], d1[0], d2[0]}, [r0]
vst3.32 {d0[0], d1[0], d2[0]}, [r0]
vst3.16 {d0[0], d1[0], d2[0]}, [r0]
vst3.8 {d0[0], d1[0], d2[0]}, [r0]
vst3.32 {d0[0], d1[0], d2[0]}, [r0]
vst3.16 {d0[0], d1[0], d2[0]}, [r0]
vst3.8 {d0[0], d1[0], d2[0]}, [r0]
vst3.32 {d0[0], d1[0], d2[0]}, [r0]
vst3.16 {d0[0], d1[0], d2[0]}, [r0]
vst3.32 {d0[0], d1[0], d2[0]}, [r0]
vst3.16 {d0[0], d1[0], d2[0]}, [r0]
vst3.32 {d0[0], d1[0], d2[0]}, [r0]
vst3.16 {d0[0], d1[0], d2[0]}, [r0]
vld4.32 {d0, d1, d2, d3}, [r0]
vld4.16 {d0, d1, d2, d3}, [r0]
vld4.8 {d0, d1, d2, d3}, [r0]
vld4.32 {d0, d1, d2, d3}, [r0]
vld4.16 {d0, d1, d2, d3}, [r0]
vld4.8 {d0, d1, d2, d3}, [r0]
vld4.32 {d0, d1, d2, d3}, [r0]
vld4.16 {d0, d1, d2, d3}, [r0]
vld4.8 {d0, d1, d2, d3}, [r0]
vld1.64 {d0, d1, d2, d3}, [r0]
vld1.64 {d0, d1, d2, d3}, [r0]
vld4.32 {d0, d1, d2, d3}, [r0]
vld4.16 {d0, d1, d2, d3}, [r0]
vld4.8 {d0, d1, d2, d3}, [r0]
vld4.32 {d0, d1, d2, d3}, [r0]
vld4.16 {d0, d1, d2, d3}, [r0]
vld4.8 {d0, d1, d2, d3}, [r0]
vld4.32 {d0, d1, d2, d3}, [r0]
vld4.16 {d0, d1, d2, d3}, [r0]
vld4.8 {d0, d1, d2, d3}, [r0]
vld4.32 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.16 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.8 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.32 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.16 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.8 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.32 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.16 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.8 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.32 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.16 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.32 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.16 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.32 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.16 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vld4.32 {d0[], d1[], d2[], d3[]}, [r0]
vld4.16 {d0[], d1[], d2[], d3[]}, [r0]
vld4.8 {d0[], d1[], d2[], d3[]}, [r0]
vld4.32 {d0[], d1[], d2[], d3[]}, [r0]
vld4.16 {d0[], d1[], d2[], d3[]}, [r0]
vld4.8 {d0[], d1[], d2[], d3[]}, [r0]
vld4.32 {d0[], d1[], d2[], d3[]}, [r0]
vld4.16 {d0[], d1[], d2[], d3[]}, [r0]
vld4.8 {d0[], d1[], d2[], d3[]}, [r0]
vld1.64 {d0, d1, d2, d3}, [r0]
vld1.64 {d0, d1, d2, d3}, [r0]
vst4.32 {d0, d1, d2, d3}, [r0]
vst4.16 {d0, d1, d2, d3}, [r0]
vst4.8 {d0, d1, d2, d3}, [r0]
vst4.32 {d0, d1, d2, d3}, [r0]
vst4.16 {d0, d1, d2, d3}, [r0]
vst4.8 {d0, d1, d2, d3}, [r0]
vst4.32 {d0, d1, d2, d3}, [r0]
vst4.16 {d0, d1, d2, d3}, [r0]
vst4.8 {d0, d1, d2, d3}, [r0]
vst1.64 {d0, d1, d2, d3}, [r0]
vst1.64 {d0, d1, d2, d3}, [r0]
vst4.32 {d0, d1, d2, d3}, [r0]
vst4.16 {d0, d1, d2, d3}, [r0]
vst4.8 {d0, d1, d2, d3}, [r0]
vst4.32 {d0, d1, d2, d3}, [r0]
vst4.16 {d0, d1, d2, d3}, [r0]
vst4.8 {d0, d1, d2, d3}, [r0]
vst4.32 {d0, d1, d2, d3}, [r0]
vst4.16 {d0, d1, d2, d3}, [r0]
vst4.8 {d0, d1, d2, d3}, [r0]
vst4.32 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vst4.16 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vst4.8 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vst4.32 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vst4.16 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vst4.8 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vst4.32 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vst4.16 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vst4.8 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vst4.32 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vst4.16 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vst4.32 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vst4.16 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vst4.32 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vst4.16 {d0[0], d1[0], d2[0], d3[0]}, [r0]
vand d0, d0, d0
vand d0, d0, d0
vand d0, d0, d0
vand d0, d0, d0
vand d0, d0, d0
vand d0, d0, d0
vand q0, q0, q0
vand q0, q0, q0
vand q0, q0, q0
vand q0, q0, q0
vand q0, q0, q0
vand q0, q0, q0
vand q0, q0, q0
vand q0, q0, q0
vorr d0, d0, d0
vorr d0, d0, d0
vorr d0, d0, d0
vorr d0, d0, d0
vorr d0, d0, d0
vorr d0, d0, d0
vorr q0, q0, q0
vorr q0, q0, q0
vorr q0, q0, q0
vorr q0, q0, q0
vorr q0, q0, q0
vorr q0, q0, q0
vorr q0, q0, q0
vorr q0, q0, q0
veor d0, d0, d0
veor d0, d0, d0
veor d0, d0, d0
veor d0, d0, d0
veor d0, d0, d0
veor d0, d0, d0
veor q0, q0, q0
veor q0, q0, q0
veor q0, q0, q0
veor q0, q0, q0
veor q0, q0, q0
veor q0, q0, q0
veor q0, q0, q0
veor q0, q0, q0
vbic d0, d0, d0
vbic d0, d0, d0
vbic d0, d0, d0
vbic d0, d0, d0
vbic d0, d0, d0
vbic d0, d0, d0
vbic q0, q0, q0
vbic q0, q0, q0
vbic q0, q0, q0
vbic q0, q0, q0
vbic q0, q0, q0
vbic q0, q0, q0
vbic q0, q0, q0
vbic q0, q0, q0
vorn d0, d0, d0
vorn d0, d0, d0
vorn d0, d0, d0
vorn d0, d0, d0
vorn d0, d0, d0
vorn d0, d0, d0
vorn q0, q0, q0
vorn q0, q0, q0
vorn q0, q0, q0
vorn q0, q0, q0
vorn q0, q0, q0
vorn q0, q0, q0
vorn q0, q0, q0
vorn q0, q0, q0
For each built-in function for AVR, there is an equally named,
uppercase built-in macro defined. That way users can easily query if
or if not a specific built-in is implemented or not. For example, if
__builtin_avr_nop is available the macro
__BUILTIN_AVR_NOP is defined to 1 and undefined otherwise.
The following built-in functions map to the respective machine
instruction, i.e. nop, sei, cli, sleep,
wdr, swap, fmul, fmuls
resp. fmulsu. The three fmul* built-ins are implemented
as library call if no hardware multiplier is available.
void __builtin_avr_nop (void)
void __builtin_avr_sei (void)
void __builtin_avr_cli (void)
void __builtin_avr_sleep (void)
void __builtin_avr_wdr (void)
unsigned char __builtin_avr_swap (unsigned char)
unsigned int __builtin_avr_fmul (unsigned char, unsigned char)
int __builtin_avr_fmuls (char, char)
int __builtin_avr_fmulsu (char, unsigned char)
In order to delay execution for a specific number of cycles, GCC implements
void __builtin_avr_delay_cycles (unsigned long ticks)
ticks is the number of ticks to delay execution. Note that this
built-in does not take into account the effect of interrupts which
might increase delay time. ticks must be a compile time
integer constant; delays with a variable number of cycles are not supported.
char __builtin_avr_flash_segment (const __memx void*)
This built-in takes a byte address to the 24-bit
address space __memx and returns
the number of the flash segment (the 64 KiB chunk) where the address
points to. Counting starts at 0.
If the address does not point to flash memory, return -1.
unsigned char __builtin_avr_insert_bits (unsigned long map, unsigned char bits, unsigned char val)
Insert bits from bits into val and return the resulting value. The nibbles of map determine how the insertion is performed: Let X be the n-th nibble of map
0xf,
then the n-th bit of val is returned unaltered.
0xe,
then the n-th result bit is undefined.
One typical use case for this built-in is adjusting input and output values to non-contiguous port layouts. Some examples:
// same as val, bits is unused
__builtin_avr_insert_bits (0xffffffff, bits, val)
// same as bits, val is unused
__builtin_avr_insert_bits (0x76543210, bits, val)
// same as rotating bits by 4
__builtin_avr_insert_bits (0x32107654, bits, 0)
// high-nibble of result is the high-nibble of val
// low-nibble of result is the low-nibble of bits
__builtin_avr_insert_bits (0xffff3210, bits, val)
// reverse the bit order of bits
__builtin_avr_insert_bits (0x01234567, bits, 0)
Currently, there are two Blackfin-specific built-in functions. These are
used for generating CSYNC and SSYNC machine insns without
using inline assembly; by using these built-in functions the compiler can
automatically add workarounds for hardware errata involving these
instructions. These functions are named as follows:
void __builtin_bfin_csync (void)
void __builtin_bfin_ssync (void)
GCC provides many FR-V-specific built-in functions. In general,
these functions are intended to be compatible with those described
by FR-V Family, Softune C/C++ Compiler Manual (V6), Fujitsu
Semiconductor. The two exceptions are __MDUNPACKH and
__MBTOHE, the gcc forms of which pass 128-bit values by
pointer rather than by value.
Most of the functions are named after specific FR-V instructions. Such functions are said to be “directly mapped” and are summarized here in tabular form.
The arguments to the built-in functions can be divided into three groups: register numbers, compile-time constants and run-time values. In order to make this classification clear at a glance, the arguments and return values are given the following pseudo types:
| Pseudo type | Real C type | Constant? | Description
|
uh | unsigned short | No | an unsigned halfword
|
uw1 | unsigned int | No | an unsigned word
|
sw1 | int | No | a signed word
|
uw2 | unsigned long long | No | an unsigned doubleword
|
sw2 | long long | No | a signed doubleword
|
const | int | Yes | an integer constant
|
acc | int | Yes | an ACC register number
|
iacc | int | Yes | an IACC register number
|
These pseudo types are not defined by GCC, they are simply a notational convenience used in this manual.
Arguments of type uh, uw1, sw1, uw2
and sw2 are evaluated at run time. They correspond to
register operands in the underlying FR-V instructions.
const arguments represent immediate operands in the underlying
FR-V instructions. They must be compile-time constants.
acc arguments are evaluated at compile time and specify the number
of an accumulator register. For example, an acc argument of 2
will select the ACC2 register.
iacc arguments are similar to acc arguments but specify the
number of an IACC register. See see Other Built-in Functions
for more details.
The functions listed below map directly to FR-V I-type instructions.
| Function prototype | Example usage | Assembly output
|
sw1 __ADDSS (sw1, sw1)
| c = __ADDSS (a, b)
| ADDSS a,b,c
|
sw1 __SCAN (sw1, sw1)
| c = __SCAN (a, b)
| SCAN a,b,c
|
sw1 __SCUTSS (sw1)
| b = __SCUTSS (a)
| SCUTSS a,b
|
sw1 __SLASS (sw1, sw1)
| c = __SLASS (a, b)
| SLASS a,b,c
|
void __SMASS (sw1, sw1)
| __SMASS (a, b)
| SMASS a,b
|
void __SMSSS (sw1, sw1)
| __SMSSS (a, b)
| SMSSS a,b
|
void __SMU (sw1, sw1)
| __SMU (a, b)
| SMU a,b
|
sw2 __SMUL (sw1, sw1)
| c = __SMUL (a, b)
| SMUL a,b,c
|
sw1 __SUBSS (sw1, sw1)
| c = __SUBSS (a, b)
| SUBSS a,b,c
|
uw2 __UMUL (uw1, uw1)
| c = __UMUL (a, b)
| UMUL a,b,c
|
The functions listed below map directly to FR-V M-type instructions.
| Function prototype | Example usage | Assembly output
|
uw1 __MABSHS (sw1)
| b = __MABSHS (a)
| MABSHS a,b
|
void __MADDACCS (acc, acc)
| __MADDACCS (b, a)
| MADDACCS a,b
|
sw1 __MADDHSS (sw1, sw1)
| c = __MADDHSS (a, b)
| MADDHSS a,b,c
|
uw1 __MADDHUS (uw1, uw1)
| c = __MADDHUS (a, b)
| MADDHUS a,b,c
|
uw1 __MAND (uw1, uw1)
| c = __MAND (a, b)
| MAND a,b,c
|
void __MASACCS (acc, acc)
| __MASACCS (b, a)
| MASACCS a,b
|
uw1 __MAVEH (uw1, uw1)
| c = __MAVEH (a, b)
| MAVEH a,b,c
|
uw2 __MBTOH (uw1)
| b = __MBTOH (a)
| MBTOH a,b
|
void __MBTOHE (uw1 *, uw1)
| __MBTOHE (&b, a)
| MBTOHE a,b
|
void __MCLRACC (acc)
| __MCLRACC (a)
| MCLRACC a
|
void __MCLRACCA (void)
| __MCLRACCA ()
| MCLRACCA
|
uw1 __Mcop1 (uw1, uw1)
| c = __Mcop1 (a, b)
| Mcop1 a,b,c
|
uw1 __Mcop2 (uw1, uw1)
| c = __Mcop2 (a, b)
| Mcop2 a,b,c
|
uw1 __MCPLHI (uw2, const)
| c = __MCPLHI (a, b)
| MCPLHI a,#b,c
|
uw1 __MCPLI (uw2, const)
| c = __MCPLI (a, b)
| MCPLI a,#b,c
|
void __MCPXIS (acc, sw1, sw1)
| __MCPXIS (c, a, b)
| MCPXIS a,b,c
|
void __MCPXIU (acc, uw1, uw1)
| __MCPXIU (c, a, b)
| MCPXIU a,b,c
|
void __MCPXRS (acc, sw1, sw1)
| __MCPXRS (c, a, b)
| MCPXRS a,b,c
|
void __MCPXRU (acc, uw1, uw1)
| __MCPXRU (c, a, b)
| MCPXRU a,b,c
|
uw1 __MCUT (acc, uw1)
| c = __MCUT (a, b)
| MCUT a,b,c
|
uw1 __MCUTSS (acc, sw1)
| c = __MCUTSS (a, b)
| MCUTSS a,b,c
|
void __MDADDACCS (acc, acc)
| __MDADDACCS (b, a)
| MDADDACCS a,b
|
void __MDASACCS (acc, acc)
| __MDASACCS (b, a)
| MDASACCS a,b
|
uw2 __MDCUTSSI (acc, const)
| c = __MDCUTSSI (a, b)
| MDCUTSSI a,#b,c
|
uw2 __MDPACKH (uw2, uw2)
| c = __MDPACKH (a, b)
| MDPACKH a,b,c
|
uw2 __MDROTLI (uw2, const)
| c = __MDROTLI (a, b)
| MDROTLI a,#b,c
|
void __MDSUBACCS (acc, acc)
| __MDSUBACCS (b, a)
| MDSUBACCS a,b
|
void __MDUNPACKH (uw1 *, uw2)
| __MDUNPACKH (&b, a)
| MDUNPACKH a,b
|
uw2 __MEXPDHD (uw1, const)
| c = __MEXPDHD (a, b)
| MEXPDHD a,#b,c
|
uw1 __MEXPDHW (uw1, const)
| c = __MEXPDHW (a, b)
| MEXPDHW a,#b,c
|
uw1 __MHDSETH (uw1, const)
| c = __MHDSETH (a, b)
| MHDSETH a,#b,c
|
sw1 __MHDSETS (const)
| b = __MHDSETS (a)
| MHDSETS #a,b
|
uw1 __MHSETHIH (uw1, const)
| b = __MHSETHIH (b, a)
| MHSETHIH #a,b
|
sw1 __MHSETHIS (sw1, const)
| b = __MHSETHIS (b, a)
| MHSETHIS #a,b
|
uw1 __MHSETLOH (uw1, const)
| b = __MHSETLOH (b, a)
| MHSETLOH #a,b
|
sw1 __MHSETLOS (sw1, const)
| b = __MHSETLOS (b, a)
| MHSETLOS #a,b
|
uw1 __MHTOB (uw2)
| b = __MHTOB (a)
| MHTOB a,b
|
void __MMACHS (acc, sw1, sw1)
| __MMACHS (c, a, b)
| MMACHS a,b,c
|
void __MMACHU (acc, uw1, uw1)
| __MMACHU (c, a, b)
| MMACHU a,b,c
|
void __MMRDHS (acc, sw1, sw1)
| __MMRDHS (c, a, b)
| MMRDHS a,b,c
|
void __MMRDHU (acc, uw1, uw1)
| __MMRDHU (c, a, b)
| MMRDHU a,b,c
|
void __MMULHS (acc, sw1, sw1)
| __MMULHS (c, a, b)
| MMULHS a,b,c
|
void __MMULHU (acc, uw1, uw1)
| __MMULHU (c, a, b)
| MMULHU a,b,c
|
void __MMULXHS (acc, sw1, sw1)
| __MMULXHS (c, a, b)
| MMULXHS a,b,c
|
void __MMULXHU (acc, uw1, uw1)
| __MMULXHU (c, a, b)
| MMULXHU a,b,c
|
uw1 __MNOT (uw1)
| b = __MNOT (a)
| MNOT a,b
|
uw1 __MOR (uw1, uw1)
| c = __MOR (a, b)
| MOR a,b,c
|
uw1 __MPACKH (uh, uh)
| c = __MPACKH (a, b)
| MPACKH a,b,c
|
sw2 __MQADDHSS (sw2, sw2)
| c = __MQADDHSS (a, b)
| MQADDHSS a,b,c
|
uw2 __MQADDHUS (uw2, uw2)
| c = __MQADDHUS (a, b)
| MQADDHUS a,b,c
|
void __MQCPXIS (acc, sw2, sw2)
| __MQCPXIS (c, a, b)
| MQCPXIS a,b,c
|
void __MQCPXIU (acc, uw2, uw2)
| __MQCPXIU (c, a, b)
| MQCPXIU a,b,c
|
void __MQCPXRS (acc, sw2, sw2)
| __MQCPXRS (c, a, b)
| MQCPXRS a,b,c
|
void __MQCPXRU (acc, uw2, uw2)
| __MQCPXRU (c, a, b)
| MQCPXRU a,b,c
|
sw2 __MQLCLRHS (sw2, sw2)
| c = __MQLCLRHS (a, b)
| MQLCLRHS a,b,c
|
sw2 __MQLMTHS (sw2, sw2)
| c = __MQLMTHS (a, b)
| MQLMTHS a,b,c
|
void __MQMACHS (acc, sw2, sw2)
| __MQMACHS (c, a, b)
| MQMACHS a,b,c
|
void __MQMACHU (acc, uw2, uw2)
| __MQMACHU (c, a, b)
| MQMACHU a,b,c
|
void __MQMACXHS (acc, sw2, sw2)
| __MQMACXHS (c, a, b)
| MQMACXHS a,b,c
|
void __MQMULHS (acc, sw2, sw2)
| __MQMULHS (c, a, b)
| MQMULHS a,b,c
|
void __MQMULHU (acc, uw2, uw2)
| __MQMULHU (c, a, b)
| MQMULHU a,b,c
|
void __MQMULXHS (acc, sw2, sw2)
| __MQMULXHS (c, a, b)
| MQMULXHS a,b,c
|
void __MQMULXHU (acc, uw2, uw2)
| __MQMULXHU (c, a, b)
| MQMULXHU a,b,c
|
sw2 __MQSATHS (sw2, sw2)
| c = __MQSATHS (a, b)
| MQSATHS a,b,c
|
uw2 __MQSLLHI (uw2, int)
| c = __MQSLLHI (a, b)
| MQSLLHI a,b,c
|
sw2 __MQSRAHI (sw2, int)
| c = __MQSRAHI (a, b)
| MQSRAHI a,b,c
|
sw2 __MQSUBHSS (sw2, sw2)
| c = __MQSUBHSS (a, b)
| MQSUBHSS a,b,c
|
uw2 __MQSUBHUS (uw2, uw2)
| c = __MQSUBHUS (a, b)
| MQSUBHUS a,b,c
|
void __MQXMACHS (acc, sw2, sw2)
| __MQXMACHS (c, a, b)
| MQXMACHS a,b,c
|
void __MQXMACXHS (acc, sw2, sw2)
| __MQXMACXHS (c, a, b)
| MQXMACXHS a,b,c
|
uw1 __MRDACC (acc)
| b = __MRDACC (a)
| MRDACC a,b
|
uw1 __MRDACCG (acc)
| b = __MRDACCG (a)
| MRDACCG a,b
|
uw1 __MROTLI (uw1, const)
| c = __MROTLI (a, b)
| MROTLI a,#b,c
|
uw1 __MROTRI (uw1, const)
| c = __MROTRI (a, b)
| MROTRI a,#b,c
|
sw1 __MSATHS (sw1, sw1)
| c = __MSATHS (a, b)
| MSATHS a,b,c
|
uw1 __MSATHU (uw1, uw1)
| c = __MSATHU (a, b)
| MSATHU a,b,c
|
uw1 __MSLLHI (uw1, const)
| c = __MSLLHI (a, b)
| MSLLHI a,#b,c
|
sw1 __MSRAHI (sw1, const)
| c = __MSRAHI (a, b)
| MSRAHI a,#b,c
|
uw1 __MSRLHI (uw1, const)
| c = __MSRLHI (a, b)
| MSRLHI a,#b,c
|
void __MSUBACCS (acc, acc)
| __MSUBACCS (b, a)
| MSUBACCS a,b
|
sw1 __MSUBHSS (sw1, sw1)
| c = __MSUBHSS (a, b)
| MSUBHSS a,b,c
|
uw1 __MSUBHUS (uw1, uw1)
| c = __MSUBHUS (a, b)
| MSUBHUS a,b,c
|
void __MTRAP (void)
| __MTRAP ()
| MTRAP
|
uw2 __MUNPACKH (uw1)
| b = __MUNPACKH (a)
| MUNPACKH a,b
|
uw1 __MWCUT (uw2, uw1)
| c = __MWCUT (a, b)
| MWCUT a,b,c
|
void __MWTACC (acc, uw1)
| __MWTACC (b, a)
| MWTACC a,b
|
void __MWTACCG (acc, uw1)
| __MWTACCG (b, a)
| MWTACCG a,b
|
uw1 __MXOR (uw1, uw1)
| c = __MXOR (a, b)
| MXOR a,b,c
|
This sections describes built-in functions related to read and write
instructions to access memory. These functions generate
membar instructions to flush the I/O load and stores where
appropriate, as described in Fujitsu's manual described above.
unsigned char __builtin_read8 (void *data)unsigned short __builtin_read16 (void *data)unsigned long __builtin_read32 (void *data)unsigned long long __builtin_read64 (void *data)
void __builtin_write8 (void *data, unsigned char datum)void __builtin_write16 (void *data, unsigned short datum)void __builtin_write32 (void *data, unsigned long datum)void __builtin_write64 (void *data, unsigned long long datum)This section describes built-in functions that are not named after a specific FR-V instruction.
sw2 __IACCreadll (iacc reg)sw1 __IACCreadl (iacc reg)void __IACCsetll (iacc reg, sw2 x)void __IACCsetl (iacc reg, sw1 x)void __data_prefetch0 (const void *x)dcpl instruction to load the contents of address x
into the data cache.
void __data_prefetch (const void *x)nldub instruction to load the contents of address x
into the data cache. The instruction will be issued in slot I1.
These built-in functions are available for the i386 and x86-64 family of computers, depending on the command-line switches used.
Note that, if you specify command-line switches such as -msse, the compiler could use the extended instruction sets even if the built-ins are not used explicitly in the program. For this reason, applications which perform runtime CPU detection must compile separate files for each supported architecture, using the appropriate flags. In particular, the file containing the CPU detection code should be compiled without these options.
The following machine modes are available for use with MMX built-in functions
(see Vector Extensions): V2SI for a vector of two 32-bit integers,
V4HI for a vector of four 16-bit integers, and V8QI for a
vector of eight 8-bit integers. Some of the built-in functions operate on
MMX registers as a whole 64-bit entity, these use V1DI as their mode.
If 3DNow! extensions are enabled, V2SF is used as a mode for a vector
of two 32-bit floating point values.
If SSE extensions are enabled, V4SF is used for a vector of four 32-bit
floating point values. Some instructions use a vector of four 32-bit
integers, these use V4SI. Finally, some instructions operate on an
entire vector register, interpreting it as a 128-bit integer, these use mode
TI.
In 64-bit mode, the x86-64 family of processors uses additional built-in
functions for efficient use of TF (__float128) 128-bit
floating point and TC 128-bit complex floating point values.
The following floating point built-in functions are available in 64-bit mode. All of them implement the function that is part of the name.
__float128 __builtin_fabsq (__float128)
__float128 __builtin_copysignq (__float128, __float128)
The following built-in function is always available.
void __builtin_ia32_pause (void)pause machine instruction with a compiler memory
barrier.
The following floating point built-in functions are made available in the 64-bit mode.
__float128 __builtin_infq (void)__builtin_inf, except the return type is __float128.
__float128 __builtin_huge_valq (void)__builtin_huge_val, except the return type is __float128.
The following built-in functions are made available by -mmmx. All of them generate the machine instruction that is part of the name.
v8qi __builtin_ia32_paddb (v8qi, v8qi)
v4hi __builtin_ia32_paddw (v4hi, v4hi)
v2si __builtin_ia32_paddd (v2si, v2si)
v8qi __builtin_ia32_psubb (v8qi, v8qi)
v4hi __builtin_ia32_psubw (v4hi, v4hi)
v2si __builtin_ia32_psubd (v2si, v2si)
v8qi __builtin_ia32_paddsb (v8qi, v8qi)
v4hi __builtin_ia32_paddsw (v4hi, v4hi)
v8qi __builtin_ia32_psubsb (v8qi, v8qi)
v4hi __builtin_ia32_psubsw (v4hi, v4hi)
v8qi __builtin_ia32_paddusb (v8qi, v8qi)
v4hi __builtin_ia32_paddusw (v4hi, v4hi)
v8qi __builtin_ia32_psubusb (v8qi, v8qi)
v4hi __builtin_ia32_psubusw (v4hi, v4hi)
v4hi __builtin_ia32_pmullw (v4hi, v4hi)
v4hi __builtin_ia32_pmulhw (v4hi, v4hi)
di __builtin_ia32_pand (di, di)
di __builtin_ia32_pandn (di,di)
di __builtin_ia32_por (di, di)
di __builtin_ia32_pxor (di, di)
v8qi __builtin_ia32_pcmpeqb (v8qi, v8qi)
v4hi __builtin_ia32_pcmpeqw (v4hi, v4hi)
v2si __builtin_ia32_pcmpeqd (v2si, v2si)
v8qi __builtin_ia32_pcmpgtb (v8qi, v8qi)
v4hi __builtin_ia32_pcmpgtw (v4hi, v4hi)
v2si __builtin_ia32_pcmpgtd (v2si, v2si)
v8qi __builtin_ia32_punpckhbw (v8qi, v8qi)
v4hi __builtin_ia32_punpckhwd (v4hi, v4hi)
v2si __builtin_ia32_punpckhdq (v2si, v2si)
v8qi __builtin_ia32_punpcklbw (v8qi, v8qi)
v4hi __builtin_ia32_punpcklwd (v4hi, v4hi)
v2si __builtin_ia32_punpckldq (v2si, v2si)
v8qi __builtin_ia32_packsswb (v4hi, v4hi)
v4hi __builtin_ia32_packssdw (v2si, v2si)
v8qi __builtin_ia32_packuswb (v4hi, v4hi)
v4hi __builtin_ia32_psllw (v4hi, v4hi)
v2si __builtin_ia32_pslld (v2si, v2si)
v1di __builtin_ia32_psllq (v1di, v1di)
v4hi __builtin_ia32_psrlw (v4hi, v4hi)
v2si __builtin_ia32_psrld (v2si, v2si)
v1di __builtin_ia32_psrlq (v1di, v1di)
v4hi __builtin_ia32_psraw (v4hi, v4hi)
v2si __builtin_ia32_psrad (v2si, v2si)
v4hi __builtin_ia32_psllwi (v4hi, int)
v2si __builtin_ia32_pslldi (v2si, int)
v1di __builtin_ia32_psllqi (v1di, int)
v4hi __builtin_ia32_psrlwi (v4hi, int)
v2si __builtin_ia32_psrldi (v2si, int)
v1di __builtin_ia32_psrlqi (v1di, int)
v4hi __builtin_ia32_psrawi (v4hi, int)
v2si __builtin_ia32_psradi (v2si, int)
The following built-in functions are made available either with -msse, or with a combination of -m3dnow and -march=athlon. All of them generate the machine instruction that is part of the name.
v4hi __builtin_ia32_pmulhuw (v4hi, v4hi)
v8qi __builtin_ia32_pavgb (v8qi, v8qi)
v4hi __builtin_ia32_pavgw (v4hi, v4hi)
v1di __builtin_ia32_psadbw (v8qi, v8qi)
v8qi __builtin_ia32_pmaxub (v8qi, v8qi)
v4hi __builtin_ia32_pmaxsw (v4hi, v4hi)
v8qi __builtin_ia32_pminub (v8qi, v8qi)
v4hi __builtin_ia32_pminsw (v4hi, v4hi)
int __builtin_ia32_pextrw (v4hi, int)
v4hi __builtin_ia32_pinsrw (v4hi, int, int)
int __builtin_ia32_pmovmskb (v8qi)
void __builtin_ia32_maskmovq (v8qi, v8qi, char *)
void __builtin_ia32_movntq (di *, di)
void __builtin_ia32_sfence (void)
The following built-in functions are available when -msse is used. All of them generate the machine instruction that is part of the name.
int __builtin_ia32_comieq (v4sf, v4sf)
int __builtin_ia32_comineq (v4sf, v4sf)
int __builtin_ia32_comilt (v4sf, v4sf)
int __builtin_ia32_comile (v4sf, v4sf)
int __builtin_ia32_comigt (v4sf, v4sf)
int __builtin_ia32_comige (v4sf, v4sf)
int __builtin_ia32_ucomieq (v4sf, v4sf)
int __builtin_ia32_ucomineq (v4sf, v4sf)
int __builtin_ia32_ucomilt (v4sf, v4sf)
int __builtin_ia32_ucomile (v4sf, v4sf)
int __builtin_ia32_ucomigt (v4sf, v4sf)
int __builtin_ia32_ucomige (v4sf, v4sf)
v4sf __builtin_ia32_addps (v4sf, v4sf)
v4sf __builtin_ia32_subps (v4sf, v4sf)
v4sf __builtin_ia32_mulps (v4sf, v4sf)
v4sf __builtin_ia32_divps (v4sf, v4sf)
v4sf __builtin_ia32_addss (v4sf, v4sf)
v4sf __builtin_ia32_subss (v4sf, v4sf)
v4sf __builtin_ia32_mulss (v4sf, v4sf)
v4sf __builtin_ia32_divss (v4sf, v4sf)
v4si __builtin_ia32_cmpeqps (v4sf, v4sf)
v4si __builtin_ia32_cmpltps (v4sf, v4sf)
v4si __builtin_ia32_cmpleps (v4sf, v4sf)
v4si __builtin_ia32_cmpgtps (v4sf, v4sf)
v4si __builtin_ia32_cmpgeps (v4sf, v4sf)
v4si __builtin_ia32_cmpunordps (v4sf, v4sf)
v4si __builtin_ia32_cmpneqps (v4sf, v4sf)
v4si __builtin_ia32_cmpnltps (v4sf, v4sf)
v4si __builtin_ia32_cmpnleps (v4sf, v4sf)
v4si __builtin_ia32_cmpngtps (v4sf, v4sf)
v4si __builtin_ia32_cmpngeps (v4sf, v4sf)
v4si __builtin_ia32_cmpordps (v4sf, v4sf)
v4si __builtin_ia32_cmpeqss (v4sf, v4sf)
v4si __builtin_ia32_cmpltss (v4sf, v4sf)
v4si __builtin_ia32_cmpless (v4sf, v4sf)
v4si __builtin_ia32_cmpunordss (v4sf, v4sf)
v4si __builtin_ia32_cmpneqss (v4sf, v4sf)
v4si __builtin_ia32_cmpnlts (v4sf, v4sf)
v4si __builtin_ia32_cmpnless (v4sf, v4sf)
v4si __builtin_ia32_cmpordss (v4sf, v4sf)
v4sf __builtin_ia32_maxps (v4sf, v4sf)
v4sf __builtin_ia32_maxss (v4sf, v4sf)
v4sf __builtin_ia32_minps (v4sf, v4sf)
v4sf __builtin_ia32_minss (v4sf, v4sf)
v4sf __builtin_ia32_andps (v4sf, v4sf)
v4sf __builtin_ia32_andnps (v4sf, v4sf)
v4sf __builtin_ia32_orps (v4sf, v4sf)
v4sf __builtin_ia32_xorps (v4sf, v4sf)
v4sf __builtin_ia32_movss (v4sf, v4sf)
v4sf __builtin_ia32_movhlps (v4sf, v4sf)
v4sf __builtin_ia32_movlhps (v4sf, v4sf)
v4sf __builtin_ia32_unpckhps (v4sf, v4sf)
v4sf __builtin_ia32_unpcklps (v4sf, v4sf)
v4sf __builtin_ia32_cvtpi2ps (v4sf, v2si)
v4sf __builtin_ia32_cvtsi2ss (v4sf, int)
v2si __builtin_ia32_cvtps2pi (v4sf)
int __builtin_ia32_cvtss2si (v4sf)
v2si __builtin_ia32_cvttps2pi (v4sf)
int __builtin_ia32_cvttss2si (v4sf)
v4sf __builtin_ia32_rcpps (v4sf)
v4sf __builtin_ia32_rsqrtps (v4sf)
v4sf __builtin_ia32_sqrtps (v4sf)
v4sf __builtin_ia32_rcpss (v4sf)
v4sf __builtin_ia32_rsqrtss (v4sf)
v4sf __builtin_ia32_sqrtss (v4sf)
v4sf __builtin_ia32_shufps (v4sf, v4sf, int)
void __builtin_ia32_movntps (float *, v4sf)
int __builtin_ia32_movmskps (v4sf)
The following built-in functions are available when -msse is used.
v4sf __builtin_ia32_loadaps (float *)movaps machine instruction as a load from memory.
void __builtin_ia32_storeaps (float *, v4sf)movaps machine instruction as a store to memory.
v4sf __builtin_ia32_loadups (float *)movups machine instruction as a load from memory.
void __builtin_ia32_storeups (float *, v4sf)movups machine instruction as a store to memory.
v4sf __builtin_ia32_loadsss (float *)movss machine instruction as a load from memory.
void __builtin_ia32_storess (float *, v4sf)movss machine instruction as a store to memory.
v4sf __builtin_ia32_loadhps (v4sf, const v2sf *)movhps machine instruction as a load from memory.
v4sf __builtin_ia32_loadlps (v4sf, const v2sf *)movlps machine instruction as a load from memory
void __builtin_ia32_storehps (v2sf *, v4sf)movhps machine instruction as a store to memory.
void __builtin_ia32_storelps (v2sf *, v4sf)movlps machine instruction as a store to memory.
The following built-in functions are available when -msse2 is used. All of them generate the machine instruction that is part of the name.
int __builtin_ia32_comisdeq (v2df, v2df)
int __builtin_ia32_comisdlt (v2df, v2df)
int __builtin_ia32_comisdle (v2df, v2df)
int __builtin_ia32_comisdgt (v2df, v2df)
int __builtin_ia32_comisdge (v2df, v2df)
int __builtin_ia32_comisdneq (v2df, v2df)
int __builtin_ia32_ucomisdeq (v2df, v2df)
int __builtin_ia32_ucomisdlt (v2df, v2df)
int __builtin_ia32_ucomisdle (v2df, v2df)
int __builtin_ia32_ucomisdgt (v2df, v2df)
int __builtin_ia32_ucomisdge (v2df, v2df)
int __builtin_ia32_ucomisdneq (v2df, v2df)
v2df __builtin_ia32_cmpeqpd (v2df, v2df)
v2df __builtin_ia32_cmpltpd (v2df, v2df)
v2df __builtin_ia32_cmplepd (v2df, v2df)
v2df __builtin_ia32_cmpgtpd (v2df, v2df)
v2df __builtin_ia32_cmpgepd (v2df, v2df)
v2df __builtin_ia32_cmpunordpd (v2df, v2df)
v2df __builtin_ia32_cmpneqpd (v2df, v2df)
v2df __builtin_ia32_cmpnltpd (v2df, v2df)
v2df __builtin_ia32_cmpnlepd (v2df, v2df)
v2df __builtin_ia32_cmpngtpd (v2df, v2df)
v2df __builtin_ia32_cmpngepd (v2df, v2df)
v2df __builtin_ia32_cmpordpd (v2df, v2df)
v2df __builtin_ia32_cmpeqsd (v2df, v2df)
v2df __builtin_ia32_cmpltsd (v2df, v2df)
v2df __builtin_ia32_cmplesd (v2df, v2df)
v2df __builtin_ia32_cmpunordsd (v2df, v2df)
v2df __builtin_ia32_cmpneqsd (v2df, v2df)
v2df __builtin_ia32_cmpnltsd (v2df, v2df)
v2df __builtin_ia32_cmpnlesd (v2df, v2df)
v2df __builtin_ia32_cmpordsd (v2df, v2df)
v2di __builtin_ia32_paddq (v2di, v2di)
v2di __builtin_ia32_psubq (v2di, v2di)
v2df __builtin_ia32_addpd (v2df, v2df)
v2df __builtin_ia32_subpd (v2df, v2df)
v2df __builtin_ia32_mulpd (v2df, v2df)
v2df __builtin_ia32_divpd (v2df, v2df)
v2df __builtin_ia32_addsd (v2df, v2df)
v2df __builtin_ia32_subsd (v2df, v2df)
v2df __builtin_ia32_mulsd (v2df, v2df)
v2df __builtin_ia32_divsd (v2df, v2df)
v2df __builtin_ia32_minpd (v2df, v2df)
v2df __builtin_ia32_maxpd (v2df, v2df)
v2df __builtin_ia32_minsd (v2df, v2df)
v2df __builtin_ia32_maxsd (v2df, v2df)
v2df __builtin_ia32_andpd (v2df, v2df)
v2df __builtin_ia32_andnpd (v2df, v2df)
v2df __builtin_ia32_orpd (v2df, v2df)
v2df __builtin_ia32_xorpd (v2df, v2df)
v2df __builtin_ia32_movsd (v2df, v2df)
v2df __builtin_ia32_unpckhpd (v2df, v2df)
v2df __builtin_ia32_unpcklpd (v2df, v2df)
v16qi __builtin_ia32_paddb128 (v16qi, v16qi)
v8hi __builtin_ia32_paddw128 (v8hi, v8hi)
v4si __builtin_ia32_paddd128 (v4si, v4si)
v2di __builtin_ia32_paddq128 (v2di, v2di)
v16qi __builtin_ia32_psubb128 (v16qi, v16qi)
v8hi __builtin_ia32_psubw128 (v8hi, v8hi)
v4si __builtin_ia32_psubd128 (v4si, v4si)
v2di __builtin_ia32_psubq128 (v2di, v2di)
v8hi __builtin_ia32_pmullw128 (v8hi, v8hi)
v8hi __builtin_ia32_pmulhw128 (v8hi, v8hi)
v2di __builtin_ia32_pand128 (v2di, v2di)
v2di __builtin_ia32_pandn128 (v2di, v2di)
v2di __builtin_ia32_por128 (v2di, v2di)
v2di __builtin_ia32_pxor128 (v2di, v2di)
v16qi __builtin_ia32_pavgb128 (v16qi, v16qi)
v8hi __builtin_ia32_pavgw128 (v8hi, v8hi)
v16qi __builtin_ia32_pcmpeqb128 (v16qi, v16qi)
v8hi __builtin_ia32_pcmpeqw128 (v8hi, v8hi)
v4si __builtin_ia32_pcmpeqd128 (v4si, v4si)
v16qi __builtin_ia32_pcmpgtb128 (v16qi, v16qi)
v8hi __builtin_ia32_pcmpgtw128 (v8hi, v8hi)
v4si __builtin_ia32_pcmpgtd128 (v4si, v4si)
v16qi __builtin_ia32_pmaxub128 (v16qi, v16qi)
v8hi __builtin_ia32_pmaxsw128 (v8hi, v8hi)
v16qi __builtin_ia32_pminub128 (v16qi, v16qi)
v8hi __builtin_ia32_pminsw128 (v8hi, v8hi)
v16qi __builtin_ia32_punpckhbw128 (v16qi, v16qi)
v8hi __builtin_ia32_punpckhwd128 (v8hi, v8hi)
v4si __builtin_ia32_punpckhdq128 (v4si, v4si)
v2di __builtin_ia32_punpckhqdq128 (v2di, v2di)
v16qi __builtin_ia32_punpcklbw128 (v16qi, v16qi)
v8hi __builtin_ia32_punpcklwd128 (v8hi, v8hi)
v4si __builtin_ia32_punpckldq128 (v4si, v4si)
v2di __builtin_ia32_punpcklqdq128 (v2di, v2di)
v16qi __builtin_ia32_packsswb128 (v8hi, v8hi)
v8hi __builtin_ia32_packssdw128 (v4si, v4si)
v16qi __builtin_ia32_packuswb128 (v8hi, v8hi)
v8hi __builtin_ia32_pmulhuw128 (v8hi, v8hi)
void __builtin_ia32_maskmovdqu (v16qi, v16qi)
v2df __builtin_ia32_loadupd (double *)
void __builtin_ia32_storeupd (double *, v2df)
v2df __builtin_ia32_loadhpd (v2df, double const *)
v2df __builtin_ia32_loadlpd (v2df, double const *)
int __builtin_ia32_movmskpd (v2df)
int __builtin_ia32_pmovmskb128 (v16qi)
void __builtin_ia32_movnti (int *, int)
void __builtin_ia32_movnti64 (long long int *, long long int)
void __builtin_ia32_movntpd (double *, v2df)
void __builtin_ia32_movntdq (v2df *, v2df)
v4si __builtin_ia32_pshufd (v4si, int)
v8hi __builtin_ia32_pshuflw (v8hi, int)
v8hi __builtin_ia32_pshufhw (v8hi, int)
v2di __builtin_ia32_psadbw128 (v16qi, v16qi)
v2df __builtin_ia32_sqrtpd (v2df)
v2df __builtin_ia32_sqrtsd (v2df)
v2df __builtin_ia32_shufpd (v2df, v2df, int)
v2df __builtin_ia32_cvtdq2pd (v4si)
v4sf __builtin_ia32_cvtdq2ps (v4si)
v4si __builtin_ia32_cvtpd2dq (v2df)
v2si __builtin_ia32_cvtpd2pi (v2df)
v4sf __builtin_ia32_cvtpd2ps (v2df)
v4si __builtin_ia32_cvttpd2dq (v2df)
v2si __builtin_ia32_cvttpd2pi (v2df)
v2df __builtin_ia32_cvtpi2pd (v2si)
int __builtin_ia32_cvtsd2si (v2df)
int __builtin_ia32_cvttsd2si (v2df)
long long __builtin_ia32_cvtsd2si64 (v2df)
long long __builtin_ia32_cvttsd2si64 (v2df)
v4si __builtin_ia32_cvtps2dq (v4sf)
v2df __builtin_ia32_cvtps2pd (v4sf)
v4si __builtin_ia32_cvttps2dq (v4sf)
v2df __builtin_ia32_cvtsi2sd (v2df, int)
v2df __builtin_ia32_cvtsi642sd (v2df, long long)
v4sf __builtin_ia32_cvtsd2ss (v4sf, v2df)
v2df __builtin_ia32_cvtss2sd (v2df, v4sf)
void __builtin_ia32_clflush (const void *)
void __builtin_ia32_lfence (void)
void __builtin_ia32_mfence (void)
v16qi __builtin_ia32_loaddqu (const char *)
void __builtin_ia32_storedqu (char *, v16qi)
v1di __builtin_ia32_pmuludq (v2si, v2si)
v2di __builtin_ia32_pmuludq128 (v4si, v4si)
v8hi __builtin_ia32_psllw128 (v8hi, v8hi)
v4si __builtin_ia32_pslld128 (v4si, v4si)
v2di __builtin_ia32_psllq128 (v2di, v2di)
v8hi __builtin_ia32_psrlw128 (v8hi, v8hi)
v4si __builtin_ia32_psrld128 (v4si, v4si)
v2di __builtin_ia32_psrlq128 (v2di, v2di)
v8hi __builtin_ia32_psraw128 (v8hi, v8hi)
v4si __builtin_ia32_psrad128 (v4si, v4si)
v2di __builtin_ia32_pslldqi128 (v2di, int)
v8hi __builtin_ia32_psllwi128 (v8hi, int)
v4si __builtin_ia32_pslldi128 (v4si, int)
v2di __builtin_ia32_psllqi128 (v2di, int)
v2di __builtin_ia32_psrldqi128 (v2di, int)
v8hi __builtin_ia32_psrlwi128 (v8hi, int)
v4si __builtin_ia32_psrldi128 (v4si, int)
v2di __builtin_ia32_psrlqi128 (v2di, int)
v8hi __builtin_ia32_psrawi128 (v8hi, int)
v4si __builtin_ia32_psradi128 (v4si, int)
v4si __builtin_ia32_pmaddwd128 (v8hi, v8hi)
v2di __builtin_ia32_movq128 (v2di)
The following built-in functions are available when -msse3 is used. All of them generate the machine instruction that is part of the name.
v2df __builtin_ia32_addsubpd (v2df, v2df)
v4sf __builtin_ia32_addsubps (v4sf, v4sf)
v2df __builtin_ia32_haddpd (v2df, v2df)
v4sf __builtin_ia32_haddps (v4sf, v4sf)
v2df __builtin_ia32_hsubpd (v2df, v2df)
v4sf __builtin_ia32_hsubps (v4sf, v4sf)
v16qi __builtin_ia32_lddqu (char const *)
void __builtin_ia32_monitor (void *, unsigned int, unsigned int)
v2df __builtin_ia32_movddup (v2df)
v4sf __builtin_ia32_movshdup (v4sf)
v4sf __builtin_ia32_movsldup (v4sf)
void __builtin_ia32_mwait (unsigned int, unsigned int)
The following built-in functions are available when -msse3 is used.
v2df __builtin_ia32_loadddup (double const *)movddup machine instruction as a load from memory.
The following built-in functions are available when -mssse3 is used. All of them generate the machine instruction that is part of the name with MMX registers.
v2si __builtin_ia32_phaddd (v2si, v2si)
v4hi __builtin_ia32_phaddw (v4hi, v4hi)
v4hi __builtin_ia32_phaddsw (v4hi, v4hi)
v2si __builtin_ia32_phsubd (v2si, v2si)
v4hi __builtin_ia32_phsubw (v4hi, v4hi)
v4hi __builtin_ia32_phsubsw (v4hi, v4hi)
v4hi __builtin_ia32_pmaddubsw (v8qi, v8qi)
v4hi __builtin_ia32_pmulhrsw (v4hi, v4hi)
v8qi __builtin_ia32_pshufb (v8qi, v8qi)
v8qi __builtin_ia32_psignb (v8qi, v8qi)
v2si __builtin_ia32_psignd (v2si, v2si)
v4hi __builtin_ia32_psignw (v4hi, v4hi)
v1di __builtin_ia32_palignr (v1di, v1di, int)
v8qi __builtin_ia32_pabsb (v8qi)
v2si __builtin_ia32_pabsd (v2si)
v4hi __builtin_ia32_pabsw (v4hi)
The following built-in functions are available when -mssse3 is used. All of them generate the machine instruction that is part of the name with SSE registers.
v4si __builtin_ia32_phaddd128 (v4si, v4si)
v8hi __builtin_ia32_phaddw128 (v8hi, v8hi)
v8hi __builtin_ia32_phaddsw128 (v8hi, v8hi)
v4si __builtin_ia32_phsubd128 (v4si, v4si)
v8hi __builtin_ia32_phsubw128 (v8hi, v8hi)
v8hi __builtin_ia32_phsubsw128 (v8hi, v8hi)
v8hi __builtin_ia32_pmaddubsw128 (v16qi, v16qi)
v8hi __builtin_ia32_pmulhrsw128 (v8hi, v8hi)
v16qi __builtin_ia32_pshufb128 (v16qi, v16qi)
v16qi __builtin_ia32_psignb128 (v16qi, v16qi)
v4si __builtin_ia32_psignd128 (v4si, v4si)
v8hi __builtin_ia32_psignw128 (v8hi, v8hi)
v2di __builtin_ia32_palignr128 (v2di, v2di, int)
v16qi __builtin_ia32_pabsb128 (v16qi)
v4si __builtin_ia32_pabsd128 (v4si)
v8hi __builtin_ia32_pabsw128 (v8hi)
The following built-in functions are available when -msse4.1 is used. All of them generate the machine instruction that is part of the name.
v2df __builtin_ia32_blendpd (v2df, v2df, const int)
v4sf __builtin_ia32_blendps (v4sf, v4sf, const int)
v2df __builtin_ia32_blendvpd (v2df, v2df, v2df)
v4sf __builtin_ia32_blendvps (v4sf, v4sf, v4sf)
v2df __builtin_ia32_dppd (v2df, v2df, const int)
v4sf __builtin_ia32_dpps (v4sf, v4sf, const int)
v4sf __builtin_ia32_insertps128 (v4sf, v4sf, const int)
v2di __builtin_ia32_movntdqa (v2di *);
v16qi __builtin_ia32_mpsadbw128 (v16qi, v16qi, const int)
v8hi __builtin_ia32_packusdw128 (v4si, v4si)
v16qi __builtin_ia32_pblendvb128 (v16qi, v16qi, v16qi)
v8hi __builtin_ia32_pblendw128 (v8hi, v8hi, const int)
v2di __builtin_ia32_pcmpeqq (v2di, v2di)
v8hi __builtin_ia32_phminposuw128 (v8hi)
v16qi __builtin_ia32_pmaxsb128 (v16qi, v16qi)
v4si __builtin_ia32_pmaxsd128 (v4si, v4si)
v4si __builtin_ia32_pmaxud128 (v4si, v4si)
v8hi __builtin_ia32_pmaxuw128 (v8hi, v8hi)
v16qi __builtin_ia32_pminsb128 (v16qi, v16qi)
v4si __builtin_ia32_pminsd128 (v4si, v4si)
v4si __builtin_ia32_pminud128 (v4si, v4si)
v8hi __builtin_ia32_pminuw128 (v8hi, v8hi)
v4si __builtin_ia32_pmovsxbd128 (v16qi)
v2di __builtin_ia32_pmovsxbq128 (v16qi)
v8hi __builtin_ia32_pmovsxbw128 (v16qi)
v2di __builtin_ia32_pmovsxdq128 (v4si)
v4si __builtin_ia32_pmovsxwd128 (v8hi)
v2di __builtin_ia32_pmovsxwq128 (v8hi)
v4si __builtin_ia32_pmovzxbd128 (v16qi)
v2di __builtin_ia32_pmovzxbq128 (v16qi)
v8hi __builtin_ia32_pmovzxbw128 (v16qi)
v2di __builtin_ia32_pmovzxdq128 (v4si)
v4si __builtin_ia32_pmovzxwd128 (v8hi)
v2di __builtin_ia32_pmovzxwq128 (v8hi)
v2di __builtin_ia32_pmuldq128 (v4si, v4si)
v4si __builtin_ia32_pmulld128 (v4si, v4si)
int __builtin_ia32_ptestc128 (v2di, v2di)
int __builtin_ia32_ptestnzc128 (v2di, v2di)
int __builtin_ia32_ptestz128 (v2di, v2di)
v2df __builtin_ia32_roundpd (v2df, const int)
v4sf __builtin_ia32_roundps (v4sf, const int)
v2df __builtin_ia32_roundsd (v2df, v2df, const int)
v4sf __builtin_ia32_roundss (v4sf, v4sf, const int)
The following built-in functions are available when -msse4.1 is used.
v4sf __builtin_ia32_vec_set_v4sf (v4sf, float, const int)insertps machine instruction.
int __builtin_ia32_vec_ext_v16qi (v16qi, const int)pextrb machine instruction.
v16qi __builtin_ia32_vec_set_v16qi (v16qi, int, const int)pinsrb machine instruction.
v4si __builtin_ia32_vec_set_v4si (v4si, int, const int)pinsrd machine instruction.
v2di __builtin_ia32_vec_set_v2di (v2di, long long, const int)pinsrq machine instruction in 64bit mode.
The following built-in functions are changed to generate new SSE4.1 instructions when -msse4.1 is used.
float __builtin_ia32_vec_ext_v4sf (v4sf, const int)extractps machine instruction.
int __builtin_ia32_vec_ext_v4si (v4si, const int)pextrd machine instruction.
long long __builtin_ia32_vec_ext_v2di (v2di, const int)pextrq machine instruction in 64bit mode.
The following built-in functions are available when -msse4.2 is used. All of them generate the machine instruction that is part of the name.
v16qi __builtin_ia32_pcmpestrm128 (v16qi, int, v16qi, int, const int)
int __builtin_ia32_pcmpestri128 (v16qi, int, v16qi, int, const int)
int __builtin_ia32_pcmpestria128 (v16qi, int, v16qi, int, const int)
int __builtin_ia32_pcmpestric128 (v16qi, int, v16qi, int, const int)
int __builtin_ia32_pcmpestrio128 (v16qi, int, v16qi, int, const int)
int __builtin_ia32_pcmpestris128 (v16qi, int, v16qi, int, const int)
int __builtin_ia32_pcmpestriz128 (v16qi, int, v16qi, int, const int)
v16qi __builtin_ia32_pcmpistrm128 (v16qi, v16qi, const int)
int __builtin_ia32_pcmpistri128 (v16qi, v16qi, const int)
int __builtin_ia32_pcmpistria128 (v16qi, v16qi, const int)
int __builtin_ia32_pcmpistric128 (v16qi, v16qi, const int)
int __builtin_ia32_pcmpistrio128 (v16qi, v16qi, const int)
int __builtin_ia32_pcmpistris128 (v16qi, v16qi, const int)
int __builtin_ia32_pcmpistriz128 (v16qi, v16qi, const int)
v2di __builtin_ia32_pcmpgtq (v2di, v2di)
The following built-in functions are available when -msse4.2 is used.
unsigned int __builtin_ia32_crc32qi (unsigned int, unsigned char)crc32b machine instruction.
unsigned int __builtin_ia32_crc32hi (unsigned int, unsigned short)crc32w machine instruction.
unsigned int __builtin_ia32_crc32si (unsigned int, unsigned int)crc32l machine instruction.
unsigned long long __builtin_ia32_crc32di (unsigned long long, unsigned long long)crc32q machine instruction.
The following built-in functions are changed to generate new SSE4.2 instructions when -msse4.2 is used.
int __builtin_popcount (unsigned int)popcntl machine instruction.
int __builtin_popcountl (unsigned long)popcntl or popcntq machine instruction,
depending on the size of unsigned long.
int __builtin_popcountll (unsigned long long)popcntq machine instruction.
The following built-in functions are available when -mavx is used. All of them generate the machine instruction that is part of the name.
v4df __builtin_ia32_addpd256 (v4df,v4df)
v8sf __builtin_ia32_addps256 (v8sf,v8sf)
v4df __builtin_ia32_addsubpd256 (v4df,v4df)
v8sf __builtin_ia32_addsubps256 (v8sf,v8sf)
v4df __builtin_ia32_andnpd256 (v4df,v4df)
v8sf __builtin_ia32_andnps256 (v8sf,v8sf)
v4df __builtin_ia32_andpd256 (v4df,v4df)
v8sf __builtin_ia32_andps256 (v8sf,v8sf)
v4df __builtin_ia32_blendpd256 (v4df,v4df,int)
v8sf __builtin_ia32_blendps256 (v8sf,v8sf,int)
v4df __builtin_ia32_blendvpd256 (v4df,v4df,v4df)
v8sf __builtin_ia32_blendvps256 (v8sf,v8sf,v8sf)
v2df __builtin_ia32_cmppd (v2df,v2df,int)
v4df __builtin_ia32_cmppd256 (v4df,v4df,int)
v4sf __builtin_ia32_cmpps (v4sf,v4sf,int)
v8sf __builtin_ia32_cmpps256 (v8sf,v8sf,int)
v2df __builtin_ia32_cmpsd (v2df,v2df,int)
v4sf __builtin_ia32_cmpss (v4sf,v4sf,int)
v4df __builtin_ia32_cvtdq2pd256 (v4si)
v8sf __builtin_ia32_cvtdq2ps256 (v8si)
v4si __builtin_ia32_cvtpd2dq256 (v4df)
v4sf __builtin_ia32_cvtpd2ps256 (v4df)
v8si __builtin_ia32_cvtps2dq256 (v8sf)
v4df __builtin_ia32_cvtps2pd256 (v4sf)
v4si __builtin_ia32_cvttpd2dq256 (v4df)
v8si __builtin_ia32_cvttps2dq256 (v8sf)
v4df __builtin_ia32_divpd256 (v4df,v4df)
v8sf __builtin_ia32_divps256 (v8sf,v8sf)
v8sf __builtin_ia32_dpps256 (v8sf,v8sf,int)
v4df __builtin_ia32_haddpd256 (v4df,v4df)
v8sf __builtin_ia32_haddps256 (v8sf,v8sf)
v4df __builtin_ia32_hsubpd256 (v4df,v4df)
v8sf __builtin_ia32_hsubps256 (v8sf,v8sf)
v32qi __builtin_ia32_lddqu256 (pcchar)
v32qi __builtin_ia32_loaddqu256 (pcchar)
v4df __builtin_ia32_loadupd256 (pcdouble)
v8sf __builtin_ia32_loadups256 (pcfloat)
v2df __builtin_ia32_maskloadpd (pcv2df,v2df)
v4df __builtin_ia32_maskloadpd256 (pcv4df,v4df)
v4sf __builtin_ia32_maskloadps (pcv4sf,v4sf)
v8sf __builtin_ia32_maskloadps256 (pcv8sf,v8sf)
void __builtin_ia32_maskstorepd (pv2df,v2df,v2df)
void __builtin_ia32_maskstorepd256 (pv4df,v4df,v4df)
void __builtin_ia32_maskstoreps (pv4sf,v4sf,v4sf)
void __builtin_ia32_maskstoreps256 (pv8sf,v8sf,v8sf)
v4df __builtin_ia32_maxpd256 (v4df,v4df)
v8sf __builtin_ia32_maxps256 (v8sf,v8sf)
v4df __builtin_ia32_minpd256 (v4df,v4df)
v8sf __builtin_ia32_minps256 (v8sf,v8sf)
v4df __builtin_ia32_movddup256 (v4df)
int __builtin_ia32_movmskpd256 (v4df)
int __builtin_ia32_movmskps256 (v8sf)
v8sf __builtin_ia32_movshdup256 (v8sf)
v8sf __builtin_ia32_movsldup256 (v8sf)
v4df __builtin_ia32_mulpd256 (v4df,v4df)
v8sf __builtin_ia32_mulps256 (v8sf,v8sf)
v4df __builtin_ia32_orpd256 (v4df,v4df)
v8sf __builtin_ia32_orps256 (v8sf,v8sf)
v2df __builtin_ia32_pd_pd256 (v4df)
v4df __builtin_ia32_pd256_pd (v2df)
v4sf __builtin_ia32_ps_ps256 (v8sf)
v8sf __builtin_ia32_ps256_ps (v4sf)
int __builtin_ia32_ptestc256 (v4di,v4di,ptest)
int __builtin_ia32_ptestnzc256 (v4di,v4di,ptest)
int __builtin_ia32_ptestz256 (v4di,v4di,ptest)
v8sf __builtin_ia32_rcpps256 (v8sf)
v4df __builtin_ia32_roundpd256 (v4df,int)
v8sf __builtin_ia32_roundps256 (v8sf,int)
v8sf __builtin_ia32_rsqrtps_nr256 (v8sf)
v8sf __builtin_ia32_rsqrtps256 (v8sf)
v4df __builtin_ia32_shufpd256 (v4df,v4df,int)
v8sf __builtin_ia32_shufps256 (v8sf,v8sf,int)
v4si __builtin_ia32_si_si256 (v8si)
v8si __builtin_ia32_si256_si (v4si)
v4df __builtin_ia32_sqrtpd256 (v4df)
v8sf __builtin_ia32_sqrtps_nr256 (v8sf)
v8sf __builtin_ia32_sqrtps256 (v8sf)
void __builtin_ia32_storedqu256 (pchar,v32qi)
void __builtin_ia32_storeupd256 (pdouble,v4df)
void __builtin_ia32_storeups256 (pfloat,v8sf)
v4df __builtin_ia32_subpd256 (v4df,v4df)
v8sf __builtin_ia32_subps256 (v8sf,v8sf)
v4df __builtin_ia32_unpckhpd256 (v4df,v4df)
v8sf __builtin_ia32_unpckhps256 (v8sf,v8sf)
v4df __builtin_ia32_unpcklpd256 (v4df,v4df)
v8sf __builtin_ia32_unpcklps256 (v8sf,v8sf)
v4df __builtin_ia32_vbroadcastf128_pd256 (pcv2df)
v8sf __builtin_ia32_vbroadcastf128_ps256 (pcv4sf)
v4df __builtin_ia32_vbroadcastsd256 (pcdouble)
v4sf __builtin_ia32_vbroadcastss (pcfloat)
v8sf __builtin_ia32_vbroadcastss256 (pcfloat)
v2df __builtin_ia32_vextractf128_pd256 (v4df,int)
v4sf __builtin_ia32_vextractf128_ps256 (v8sf,int)
v4si __builtin_ia32_vextractf128_si256 (v8si,int)
v4df __builtin_ia32_vinsertf128_pd256 (v4df,v2df,int)
v8sf __builtin_ia32_vinsertf128_ps256 (v8sf,v4sf,int)
v8si __builtin_ia32_vinsertf128_si256 (v8si,v4si,int)
v4df __builtin_ia32_vperm2f128_pd256 (v4df,v4df,int)
v8sf __builtin_ia32_vperm2f128_ps256 (v8sf,v8sf,int)
v8si __builtin_ia32_vperm2f128_si256 (v8si,v8si,int)
v2df __builtin_ia32_vpermil2pd (v2df,v2df,v2di,int)
v4df __builtin_ia32_vpermil2pd256 (v4df,v4df,v4di,int)
v4sf __builtin_ia32_vpermil2ps (v4sf,v4sf,v4si,int)
v8sf __builtin_ia32_vpermil2ps256 (v8sf,v8sf,v8si,int)
v2df __builtin_ia32_vpermilpd (v2df,int)
v4df __builtin_ia32_vpermilpd256 (v4df,int)
v4sf __builtin_ia32_vpermilps (v4sf,int)
v8sf __builtin_ia32_vpermilps256 (v8sf,int)
v2df __builtin_ia32_vpermilvarpd (v2df,v2di)
v4df __builtin_ia32_vpermilvarpd256 (v4df,v4di)
v4sf __builtin_ia32_vpermilvarps (v4sf,v4si)
v8sf __builtin_ia32_vpermilvarps256 (v8sf,v8si)
int __builtin_ia32_vtestcpd (v2df,v2df,ptest)
int __builtin_ia32_vtestcpd256 (v4df,v4df,ptest)
int __builtin_ia32_vtestcps (v4sf,v4sf,ptest)
int __builtin_ia32_vtestcps256 (v8sf,v8sf,ptest)
int __builtin_ia32_vtestnzcpd (v2df,v2df,ptest)
int __builtin_ia32_vtestnzcpd256 (v4df,v4df,ptest)
int __builtin_ia32_vtestnzcps (v4sf,v4sf,ptest)
int __builtin_ia32_vtestnzcps256 (v8sf,v8sf,ptest)
int __builtin_ia32_vtestzpd (v2df,v2df,ptest)
int __builtin_ia32_vtestzpd256 (v4df,v4df,ptest)
int __builtin_ia32_vtestzps (v4sf,v4sf,ptest)
int __builtin_ia32_vtestzps256 (v8sf,v8sf,ptest)
void __builtin_ia32_vzeroall (void)
void __builtin_ia32_vzeroupper (void)
v4df __builtin_ia32_xorpd256 (v4df,v4df)
v8sf __builtin_ia32_xorps256 (v8sf,v8sf)
The following built-in functions are available when -mavx2 is used. All of them generate the machine instruction that is part of the name.
v32qi __builtin_ia32_mpsadbw256 (v32qi,v32qi,v32qi,int)
v32qi __builtin_ia32_pabsb256 (v32qi)
v16hi __builtin_ia32_pabsw256 (v16hi)
v8si __builtin_ia32_pabsd256 (v8si)
v16hi builtin_ia32_packssdw256 (v8si,v8si)
v32qi __builtin_ia32_packsswb256 (v16hi,v16hi)
v16hi __builtin_ia32_packusdw256 (v8si,v8si)
v32qi __builtin_ia32_packuswb256 (v16hi,v16hi)
v32qi__builtin_ia32_paddb256 (v32qi,v32qi)
v16hi __builtin_ia32_paddw256 (v16hi,v16hi)
v8si __builtin_ia32_paddd256 (v8si,v8si)
v4di __builtin_ia32_paddq256 (v4di,v4di)
v32qi __builtin_ia32_paddsb256 (v32qi,v32qi)
v16hi __builtin_ia32_paddsw256 (v16hi,v16hi)
v32qi __builtin_ia32_paddusb256 (v32qi,v32qi)
v16hi __builtin_ia32_paddusw256 (v16hi,v16hi)
v4di __builtin_ia32_palignr256 (v4di,v4di,int)
v4di __builtin_ia32_andsi256 (v4di,v4di)
v4di __builtin_ia32_andnotsi256 (v4di,v4di)
v32qi__builtin_ia32_pavgb256 (v32qi,v32qi)
v16hi __builtin_ia32_pavgw256 (v16hi,v16hi)
v32qi __builtin_ia32_pblendvb256 (v32qi,v32qi,v32qi)
v16hi __builtin_ia32_pblendw256 (v16hi,v16hi,int)
v32qi __builtin_ia32_pcmpeqb256 (v32qi,v32qi)
v16hi __builtin_ia32_pcmpeqw256 (v16hi,v16hi)
v8si __builtin_ia32_pcmpeqd256 (c8si,v8si)
v4di __builtin_ia32_pcmpeqq256 (v4di,v4di)
v32qi __builtin_ia32_pcmpgtb256 (v32qi,v32qi)
v16hi __builtin_ia32_pcmpgtw256 (16hi,v16hi)
v8si __builtin_ia32_pcmpgtd256 (v8si,v8si)
v4di __builtin_ia32_pcmpgtq256 (v4di,v4di)
v16hi __builtin_ia32_phaddw256 (v16hi,v16hi)
v8si __builtin_ia32_phaddd256 (v8si,v8si)
v16hi __builtin_ia32_phaddsw256 (v16hi,v16hi)
v16hi __builtin_ia32_phsubw256 (v16hi,v16hi)
v8si __builtin_ia32_phsubd256 (v8si,v8si)
v16hi __builtin_ia32_phsubsw256 (v16hi,v16hi)
v32qi __builtin_ia32_pmaddubsw256 (v32qi,v32qi)
v16hi __builtin_ia32_pmaddwd256 (v16hi,v16hi)
v32qi __builtin_ia32_pmaxsb256 (v32qi,v32qi)
v16hi __builtin_ia32_pmaxsw256 (v16hi,v16hi)
v8si __builtin_ia32_pmaxsd256 (v8si,v8si)
v32qi __builtin_ia32_pmaxub256 (v32qi,v32qi)
v16hi __builtin_ia32_pmaxuw256 (v16hi,v16hi)
v8si __builtin_ia32_pmaxud256 (v8si,v8si)
v32qi __builtin_ia32_pminsb256 (v32qi,v32qi)
v16hi __builtin_ia32_pminsw256 (v16hi,v16hi)
v8si __builtin_ia32_pminsd256 (v8si,v8si)
v32qi __builtin_ia32_pminub256 (v32qi,v32qi)
v16hi __builtin_ia32_pminuw256 (v16hi,v16hi)
v8si __builtin_ia32_pminud256 (v8si,v8si)
int __builtin_ia32_pmovmskb256 (v32qi)
v16hi __builtin_ia32_pmovsxbw256 (v16qi)
v8si __builtin_ia32_pmovsxbd256 (v16qi)
v4di __builtin_ia32_pmovsxbq256 (v16qi)
v8si __builtin_ia32_pmovsxwd256 (v8hi)
v4di __builtin_ia32_pmovsxwq256 (v8hi)
v4di __builtin_ia32_pmovsxdq256 (v4si)
v16hi __builtin_ia32_pmovzxbw256 (v16qi)
v8si __builtin_ia32_pmovzxbd256 (v16qi)
v4di __builtin_ia32_pmovzxbq256 (v16qi)
v8si __builtin_ia32_pmovzxwd256 (v8hi)
v4di __builtin_ia32_pmovzxwq256 (v8hi)
v4di __builtin_ia32_pmovzxdq256 (v4si)
v4di __builtin_ia32_pmuldq256 (v8si,v8si)
v16hi __builtin_ia32_pmulhrsw256 (v16hi, v16hi)
v16hi __builtin_ia32_pmulhuw256 (v16hi,v16hi)
v16hi __builtin_ia32_pmulhw256 (v16hi,v16hi)
v16hi __builtin_ia32_pmullw256 (v16hi,v16hi)
v8si __builtin_ia32_pmulld256 (v8si,v8si)
v4di __builtin_ia32_pmuludq256 (v8si,v8si)
v4di __builtin_ia32_por256 (v4di,v4di)
v16hi __builtin_ia32_psadbw256 (v32qi,v32qi)
v32qi __builtin_ia32_pshufb256 (v32qi,v32qi)
v8si __builtin_ia32_pshufd256 (v8si,int)
v16hi __builtin_ia32_pshufhw256 (v16hi,int)
v16hi __builtin_ia32_pshuflw256 (v16hi,int)
v32qi __builtin_ia32_psignb256 (v32qi,v32qi)
v16hi __builtin_ia32_psignw256 (v16hi,v16hi)
v8si __builtin_ia32_psignd256 (v8si,v8si)
v4di __builtin_ia32_pslldqi256 (v4di,int)
v16hi __builtin_ia32_psllwi256 (16hi,int)
v16hi __builtin_ia32_psllw256(v16hi,v8hi)
v8si __builtin_ia32_pslldi256 (v8si,int)
v8si __builtin_ia32_pslld256(v8si,v4si)
v4di __builtin_ia32_psllqi256 (v4di,int)
v4di __builtin_ia32_psllq256(v4di,v2di)
v16hi __builtin_ia32_psrawi256 (v16hi,int)
v16hi __builtin_ia32_psraw256 (v16hi,v8hi)
v8si __builtin_ia32_psradi256 (v8si,int)
v8si __builtin_ia32_psrad256 (v8si,v4si)
v4di __builtin_ia32_psrldqi256 (v4di, int)
v16hi __builtin_ia32_psrlwi256 (v16hi,int)
v16hi __builtin_ia32_psrlw256 (v16hi,v8hi)
v8si __builtin_ia32_psrldi256 (v8si,int)
v8si __builtin_ia32_psrld256 (v8si,v4si)
v4di __builtin_ia32_psrlqi256 (v4di,int)
v4di __builtin_ia32_psrlq256(v4di,v2di)
v32qi __builtin_ia32_psubb256 (v32qi,v32qi)
v32hi __builtin_ia32_psubw256 (v16hi,v16hi)
v8si __builtin_ia32_psubd256 (v8si,v8si)
v4di __builtin_ia32_psubq256 (v4di,v4di)
v32qi __builtin_ia32_psubsb256 (v32qi,v32qi)
v16hi __builtin_ia32_psubsw256 (v16hi,v16hi)
v32qi __builtin_ia32_psubusb256 (v32qi,v32qi)
v16hi __builtin_ia32_psubusw256 (v16hi,v16hi)
v32qi __builtin_ia32_punpckhbw256 (v32qi,v32qi)
v16hi __builtin_ia32_punpckhwd256 (v16hi,v16hi)
v8si __builtin_ia32_punpckhdq256 (v8si,v8si)
v4di __builtin_ia32_punpckhqdq256 (v4di,v4di)
v32qi __builtin_ia32_punpcklbw256 (v32qi,v32qi)
v16hi __builtin_ia32_punpcklwd256 (v16hi,v16hi)
v8si __builtin_ia32_punpckldq256 (v8si,v8si)
v4di __builtin_ia32_punpcklqdq256 (v4di,v4di)
v4di __builtin_ia32_pxor256 (v4di,v4di)
v4di __builtin_ia32_movntdqa256 (pv4di)
v4sf __builtin_ia32_vbroadcastss_ps (v4sf)
v8sf __builtin_ia32_vbroadcastss_ps256 (v4sf)
v4df __builtin_ia32_vbroadcastsd_pd256 (v2df)
v4di __builtin_ia32_vbroadcastsi256 (v2di)
v4si __builtin_ia32_pblendd128 (v4si,v4si)
v8si __builtin_ia32_pblendd256 (v8si,v8si)
v32qi __builtin_ia32_pbroadcastb256 (v16qi)
v16hi __builtin_ia32_pbroadcastw256 (v8hi)
v8si __builtin_ia32_pbroadcastd256 (v4si)
v4di __builtin_ia32_pbroadcastq256 (v2di)
v16qi __builtin_ia32_pbroadcastb128 (v16qi)
v8hi __builtin_ia32_pbroadcastw128 (v8hi)
v4si __builtin_ia32_pbroadcastd128 (v4si)
v2di __builtin_ia32_pbroadcastq128 (v2di)
v8si __builtin_ia32_permvarsi256 (v8si,v8si)
v4df __builtin_ia32_permdf256 (v4df,int)
v8sf __builtin_ia32_permvarsf256 (v8sf,v8sf)
v4di __builtin_ia32_permdi256 (v4di,int)
v4di __builtin_ia32_permti256 (v4di,v4di,int)
v4di __builtin_ia32_extract128i256 (v4di,int)
v4di __builtin_ia32_insert128i256 (v4di,v2di,int)
v8si __builtin_ia32_maskloadd256 (pcv8si,v8si)
v4di __builtin_ia32_maskloadq256 (pcv4di,v4di)
v4si __builtin_ia32_maskloadd (pcv4si,v4si)
v2di __builtin_ia32_maskloadq (pcv2di,v2di)
void __builtin_ia32_maskstored256 (pv8si,v8si,v8si)
void __builtin_ia32_maskstoreq256 (pv4di,v4di,v4di)
void __builtin_ia32_maskstored (pv4si,v4si,v4si)
void __builtin_ia32_maskstoreq (pv2di,v2di,v2di)
v8si __builtin_ia32_psllv8si (v8si,v8si)
v4si __builtin_ia32_psllv4si (v4si,v4si)
v4di __builtin_ia32_psllv4di (v4di,v4di)
v2di __builtin_ia32_psllv2di (v2di,v2di)
v8si __builtin_ia32_psrav8si (v8si,v8si)
v4si __builtin_ia32_psrav4si (v4si,v4si)
v8si __builtin_ia32_psrlv8si (v8si,v8si)
v4si __builtin_ia32_psrlv4si (v4si,v4si)
v4di __builtin_ia32_psrlv4di (v4di,v4di)
v2di __builtin_ia32_psrlv2di (v2di,v2di)
v2df __builtin_ia32_gathersiv2df (v2df, pcdouble,v4si,v2df,int)
v4df __builtin_ia32_gathersiv4df (v4df, pcdouble,v4si,v4df,int)
v2df __builtin_ia32_gatherdiv2df (v2df, pcdouble,v2di,v2df,int)
v4df __builtin_ia32_gatherdiv4df (v4df, pcdouble,v4di,v4df,int)
v4sf __builtin_ia32_gathersiv4sf (v4sf, pcfloat,v4si,v4sf,int)
v8sf __builtin_ia32_gathersiv8sf (v8sf, pcfloat,v8si,v8sf,int)
v4sf __builtin_ia32_gatherdiv4sf (v4sf, pcfloat,v2di,v4sf,int)
v4sf __builtin_ia32_gatherdiv4sf256 (v4sf, pcfloat,v4di,v4sf,int)
v2di __builtin_ia32_gathersiv2di (v2di, pcint64,v4si,v2di,int)
v4di __builtin_ia32_gathersiv4di (v4di, pcint64,v4si,v4di,int)
v2di __builtin_ia32_gatherdiv2di (v2di, pcint64,v2di,v2di,int)
v4di __builtin_ia32_gatherdiv4di (v4di, pcint64,v4di,v4di,int)
v4si __builtin_ia32_gathersiv4si (v4si, pcint,v4si,v4si,int)
v8si __builtin_ia32_gathersiv8si (v8si, pcint,v8si,v8si,int)
v4si __builtin_ia32_gatherdiv4si (v4si, pcint,v2di,v4si,int)
v4si __builtin_ia32_gatherdiv4si256 (v4si, pcint,v4di,v4si,int)
The following built-in functions are available when -maes is used. All of them generate the machine instruction that is part of the name.
v2di __builtin_ia32_aesenc128 (v2di, v2di)
v2di __builtin_ia32_aesenclast128 (v2di, v2di)
v2di __builtin_ia32_aesdec128 (v2di, v2di)
v2di __builtin_ia32_aesdeclast128 (v2di, v2di)
v2di __builtin_ia32_aeskeygenassist128 (v2di, const int)
v2di __builtin_ia32_aesimc128 (v2di)
The following built-in function is available when -mpclmul is used.
v2di __builtin_ia32_pclmulqdq128 (v2di, v2di, const int)pclmulqdq machine instruction.
The following built-in function is available when -mfsgsbase is used. All of them generate the machine instruction that is part of the name.
unsigned int __builtin_ia32_rdfsbase32 (void)
unsigned long long __builtin_ia32_rdfsbase64 (void)
unsigned int __builtin_ia32_rdgsbase32 (void)
unsigned long long __builtin_ia32_rdgsbase64 (void)
void _writefsbase_u32 (unsigned int)
void _writefsbase_u64 (unsigned long long)
void _writegsbase_u32 (unsigned int)
void _writegsbase_u64 (unsigned long long)
The following built-in function is available when -mrdrnd is used. All of them generate the machine instruction that is part of the name.
unsigned int __builtin_ia32_rdrand16_step (unsigned short *)
unsigned int __builtin_ia32_rdrand32_step (unsigned int *)
unsigned int __builtin_ia32_rdrand64_step (unsigned long long *)
The following built-in functions are available when -msse4a is used. All of them generate the machine instruction that is part of the name.
void __builtin_ia32_movntsd (double *, v2df)
void __builtin_ia32_movntss (float *, v4sf)
v2di __builtin_ia32_extrq (v2di, v16qi)
v2di __builtin_ia32_extrqi (v2di, const unsigned int, const unsigned int)
v2di __builtin_ia32_insertq (v2di, v2di)
v2di __builtin_ia32_insertqi (v2di, v2di, const unsigned int, const unsigned int)
The following built-in functions are available when -mxop is used.
v2df __builtin_ia32_vfrczpd (v2df)
v4sf __builtin_ia32_vfrczps (v4sf)
v2df __builtin_ia32_vfrczsd (v2df, v2df)
v4sf __builtin_ia32_vfrczss (v4sf, v4sf)
v4df __builtin_ia32_vfrczpd256 (v4df)
v8sf __builtin_ia32_vfrczps256 (v8sf)
v2di __builtin_ia32_vpcmov (v2di, v2di, v2di)
v2di __builtin_ia32_vpcmov_v2di (v2di, v2di, v2di)
v4si __builtin_ia32_vpcmov_v4si (v4si, v4si, v4si)
v8hi __builtin_ia32_vpcmov_v8hi (v8hi, v8hi, v8hi)
v16qi __builtin_ia32_vpcmov_v16qi (v16qi, v16qi, v16qi)
v2df __builtin_ia32_vpcmov_v2df (v2df, v2df, v2df)
v4sf __builtin_ia32_vpcmov_v4sf (v4sf, v4sf, v4sf)
v4di __builtin_ia32_vpcmov_v4di256 (v4di, v4di, v4di)
v8si __builtin_ia32_vpcmov_v8si256 (v8si, v8si, v8si)
v16hi __builtin_ia32_vpcmov_v16hi256 (v16hi, v16hi, v16hi)
v32qi __builtin_ia32_vpcmov_v32qi256 (v32qi, v32qi, v32qi)
v4df __builtin_ia32_vpcmov_v4df256 (v4df, v4df, v4df)
v8sf __builtin_ia32_vpcmov_v8sf256 (v8sf, v8sf, v8sf)
v16qi __builtin_ia32_vpcomeqb (v16qi, v16qi)
v8hi __builtin_ia32_vpcomeqw (v8hi, v8hi)
v4si __builtin_ia32_vpcomeqd (v4si, v4si)
v2di __builtin_ia32_vpcomeqq (v2di, v2di)
v16qi __builtin_ia32_vpcomequb (v16qi, v16qi)
v4si __builtin_ia32_vpcomequd (v4si, v4si)
v2di __builtin_ia32_vpcomequq (v2di, v2di)
v8hi __builtin_ia32_vpcomequw (v8hi, v8hi)
v8hi __builtin_ia32_vpcomeqw (v8hi, v8hi)
v16qi __builtin_ia32_vpcomfalseb (v16qi, v16qi)
v4si __builtin_ia32_vpcomfalsed (v4si, v4si)
v2di __builtin_ia32_vpcomfalseq (v2di, v2di)
v16qi __builtin_ia32_vpcomfalseub (v16qi, v16qi)
v4si __builtin_ia32_vpcomfalseud (v4si, v4si)
v2di __builtin_ia32_vpcomfalseuq (v2di, v2di)
v8hi __builtin_ia32_vpcomfalseuw (v8hi, v8hi)
v8hi __builtin_ia32_vpcomfalsew (v8hi, v8hi)
v16qi __builtin_ia32_vpcomgeb (v16qi, v16qi)
v4si __builtin_ia32_vpcomged (v4si, v4si)
v2di __builtin_ia32_vpcomgeq (v2di, v2di)
v16qi __builtin_ia32_vpcomgeub (v16qi, v16qi)
v4si __builtin_ia32_vpcomgeud (v4si, v4si)
v2di __builtin_ia32_vpcomgeuq (v2di, v2di)
v8hi __builtin_ia32_vpcomgeuw (v8hi, v8hi)
v8hi __builtin_ia32_vpcomgew (v8hi, v8hi)
v16qi __builtin_ia32_vpcomgtb (v16qi, v16qi)
v4si __builtin_ia32_vpcomgtd (v4si, v4si)
v2di __builtin_ia32_vpcomgtq (v2di, v2di)
v16qi __builtin_ia32_vpcomgtub (v16qi, v16qi)
v4si __builtin_ia32_vpcomgtud (v4si, v4si)
v2di __builtin_ia32_vpcomgtuq (v2di, v2di)
v8hi __builtin_ia32_vpcomgtuw (v8hi, v8hi)
v8hi __builtin_ia32_vpcomgtw (v8hi, v8hi)
v16qi __builtin_ia32_vpcomleb (v16qi, v16qi)
v4si __builtin_ia32_vpcomled (v4si, v4si)
v2di __builtin_ia32_vpcomleq (v2di, v2di)
v16qi __builtin_ia32_vpcomleub (v16qi, v16qi)
v4si __builtin_ia32_vpcomleud (v4si, v4si)
v2di __builtin_ia32_vpcomleuq (v2di, v2di)
v8hi __builtin_ia32_vpcomleuw (v8hi, v8hi)
v8hi __builtin_ia32_vpcomlew (v8hi, v8hi)
v16qi __builtin_ia32_vpcomltb (v16qi, v16qi)
v4si __builtin_ia32_vpcomltd (v4si, v4si)
v2di __builtin_ia32_vpcomltq (v2di, v2di)
v16qi __builtin_ia32_vpcomltub (v16qi, v16qi)
v4si __builtin_ia32_vpcomltud (v4si, v4si)
v2di __builtin_ia32_vpcomltuq (v2di, v2di)
v8hi __builtin_ia32_vpcomltuw (v8hi, v8hi)
v8hi __builtin_ia32_vpcomltw (v8hi, v8hi)
v16qi __builtin_ia32_vpcomneb (v16qi, v16qi)
v4si __builtin_ia32_vpcomned (v4si, v4si)
v2di __builtin_ia32_vpcomneq (v2di, v2di)
v16qi __builtin_ia32_vpcomneub (v16qi, v16qi)
v4si __builtin_ia32_vpcomneud (v4si, v4si)
v2di __builtin_ia32_vpcomneuq (v2di, v2di)
v8hi __builtin_ia32_vpcomneuw (v8hi, v8hi)
v8hi __builtin_ia32_vpcomnew (v8hi, v8hi)
v16qi __builtin_ia32_vpcomtrueb (v16qi, v16qi)
v4si __builtin_ia32_vpcomtrued (v4si, v4si)
v2di __builtin_ia32_vpcomtrueq (v2di, v2di)
v16qi __builtin_ia32_vpcomtrueub (v16qi, v16qi)
v4si __builtin_ia32_vpcomtrueud (v4si, v4si)
v2di __builtin_ia32_vpcomtrueuq (v2di, v2di)
v8hi __builtin_ia32_vpcomtrueuw (v8hi, v8hi)
v8hi __builtin_ia32_vpcomtruew (v8hi, v8hi)
v4si __builtin_ia32_vphaddbd (v16qi)
v2di __builtin_ia32_vphaddbq (v16qi)
v8hi __builtin_ia32_vphaddbw (v16qi)
v2di __builtin_ia32_vphadddq (v4si)
v4si __builtin_ia32_vphaddubd (v16qi)
v2di __builtin_ia32_vphaddubq (v16qi)
v8hi __builtin_ia32_vphaddubw (v16qi)
v2di __builtin_ia32_vphaddudq (v4si)
v4si __builtin_ia32_vphadduwd (v8hi)
v2di __builtin_ia32_vphadduwq (v8hi)
v4si __builtin_ia32_vphaddwd (v8hi)
v2di __builtin_ia32_vphaddwq (v8hi)
v8hi __builtin_ia32_vphsubbw (v16qi)
v2di __builtin_ia32_vphsubdq (v4si)
v4si __builtin_ia32_vphsubwd (v8hi)
v4si __builtin_ia32_vpmacsdd (v4si, v4si, v4si)
v2di __builtin_ia32_vpmacsdqh (v4si, v4si, v2di)
v2di __builtin_ia32_vpmacsdql (v4si, v4si, v2di)
v4si __builtin_ia32_vpmacssdd (v4si, v4si, v4si)
v2di __builtin_ia32_vpmacssdqh (v4si, v4si, v2di)
v2di __builtin_ia32_vpmacssdql (v4si, v4si, v2di)
v4si __builtin_ia32_vpmacsswd (v8hi, v8hi, v4si)
v8hi __builtin_ia32_vpmacssww (v8hi, v8hi, v8hi)
v4si __builtin_ia32_vpmacswd (v8hi, v8hi, v4si)
v8hi __builtin_ia32_vpmacsww (v8hi, v8hi, v8hi)
v4si __builtin_ia32_vpmadcsswd (v8hi, v8hi, v4si)
v4si __builtin_ia32_vpmadcswd (v8hi, v8hi, v4si)
v16qi __builtin_ia32_vpperm (v16qi, v16qi, v16qi)
v16qi __builtin_ia32_vprotb (v16qi, v16qi)
v4si __builtin_ia32_vprotd (v4si, v4si)
v2di __builtin_ia32_vprotq (v2di, v2di)
v8hi __builtin_ia32_vprotw (v8hi, v8hi)
v16qi __builtin_ia32_vpshab (v16qi, v16qi)
v4si __builtin_ia32_vpshad (v4si, v4si)
v2di __builtin_ia32_vpshaq (v2di, v2di)
v8hi __builtin_ia32_vpshaw (v8hi, v8hi)
v16qi __builtin_ia32_vpshlb (v16qi, v16qi)
v4si __builtin_ia32_vpshld (v4si, v4si)
v2di __builtin_ia32_vpshlq (v2di, v2di)
v8hi __builtin_ia32_vpshlw (v8hi, v8hi)
The following built-in functions are available when -mfma4 is used. All of them generate the machine instruction that is part of the name with MMX registers.
v2df __builtin_ia32_fmaddpd (v2df, v2df, v2df)
v4sf __builtin_ia32_fmaddps (v4sf, v4sf, v4sf)
v2df __builtin_ia32_fmaddsd (v2df, v2df, v2df)
v4sf __builtin_ia32_fmaddss (v4sf, v4sf, v4sf)
v2df __builtin_ia32_fmsubpd (v2df, v2df, v2df)
v4sf __builtin_ia32_fmsubps (v4sf, v4sf, v4sf)
v2df __builtin_ia32_fmsubsd (v2df, v2df, v2df)
v4sf __builtin_ia32_fmsubss (v4sf, v4sf, v4sf)
v2df __builtin_ia32_fnmaddpd (v2df, v2df, v2df)
v4sf __builtin_ia32_fnmaddps (v4sf, v4sf, v4sf)
v2df __builtin_ia32_fnmaddsd (v2df, v2df, v2df)
v4sf __builtin_ia32_fnmaddss (v4sf, v4sf, v4sf)
v2df __builtin_ia32_fnmsubpd (v2df, v2df, v2df)
v4sf __builtin_ia32_fnmsubps (v4sf, v4sf, v4sf)
v2df __builtin_ia32_fnmsubsd (v2df, v2df, v2df)
v4sf __builtin_ia32_fnmsubss (v4sf, v4sf, v4sf)
v2df __builtin_ia32_fmaddsubpd (v2df, v2df, v2df)
v4sf __builtin_ia32_fmaddsubps (v4sf, v4sf, v4sf)
v2df __builtin_ia32_fmsubaddpd (v2df, v2df, v2df)
v4sf __builtin_ia32_fmsubaddps (v4sf, v4sf, v4sf)
v4df __builtin_ia32_fmaddpd256 (v4df, v4df, v4df)
v8sf __builtin_ia32_fmaddps256 (v8sf, v8sf, v8sf)
v4df __builtin_ia32_fmsubpd256 (v4df, v4df, v4df)
v8sf __builtin_ia32_fmsubps256 (v8sf, v8sf, v8sf)
v4df __builtin_ia32_fnmaddpd256 (v4df, v4df, v4df)
v8sf __builtin_ia32_fnmaddps256 (v8sf, v8sf, v8sf)
v4df __builtin_ia32_fnmsubpd256 (v4df, v4df, v4df)
v8sf __builtin_ia32_fnmsubps256 (v8sf, v8sf, v8sf)
v4df __builtin_ia32_fmaddsubpd256 (v4df, v4df, v4df)
v8sf __builtin_ia32_fmaddsubps256 (v8sf, v8sf, v8sf)
v4df __builtin_ia32_fmsubaddpd256 (v4df, v4df, v4df)
v8sf __builtin_ia32_fmsubaddps256 (v8sf, v8sf, v8sf)
The following built-in functions are available when -mlwp is used.
void __builtin_ia32_llwpcb16 (void *);
void __builtin_ia32_llwpcb32 (void *);
void __builtin_ia32_llwpcb64 (void *);
void * __builtin_ia32_llwpcb16 (void);
void * __builtin_ia32_llwpcb32 (void);
void * __builtin_ia32_llwpcb64 (void);
void __builtin_ia32_lwpval16 (unsigned short, unsigned int, unsigned short)
void __builtin_ia32_lwpval32 (unsigned int, unsigned int, unsigned int)
void __builtin_ia32_lwpval64 (unsigned __int64, unsigned int, unsigned int)
unsigned char __builtin_ia32_lwpins16 (unsigned short, unsigned int, unsigned short)
unsigned char __builtin_ia32_lwpins32 (unsigned int, unsigned int, unsigned int)
unsigned char __builtin_ia32_lwpins64 (unsigned __int64, unsigned int, unsigned int)
The following built-in functions are available when -mbmi is used. All of them generate the machine instruction that is part of the name.
unsigned int __builtin_ia32_bextr_u32(unsigned int, unsigned int);
unsigned long long __builtin_ia32_bextr_u64 (unsigned long long, unsigned long long);
The following built-in functions are available when -mbmi2 is used. All of them generate the machine instruction that is part of the name.
unsigned int _bzhi_u32 (unsigned int, unsigned int)
unsigned int _pdep_u32 (unsigned int, unsigned int)
unsigned int _pext_u32 (unsigned int, unsigned int)
unsigned long long _bzhi_u64 (unsigned long long, unsigned long long)
unsigned long long _pdep_u64 (unsigned long long, unsigned long long)
unsigned long long _pext_u64 (unsigned long long, unsigned long long)
The following built-in functions are available when -mlzcnt is used. All of them generate the machine instruction that is part of the name.
unsigned short __builtin_ia32_lzcnt_16(unsigned short);
unsigned int __builtin_ia32_lzcnt_u32(unsigned int);
unsigned long long __builtin_ia32_lzcnt_u64 (unsigned long long);
The following built-in functions are available when -mtbm is used. Both of them generate the immediate form of the bextr machine instruction.
unsigned int __builtin_ia32_bextri_u32 (unsigned int, const unsigned int);
unsigned long long __builtin_ia32_bextri_u64 (unsigned long long, const unsigned long long);
The following built-in functions are available when -m3dnow is used. All of them generate the machine instruction that is part of the name.
void __builtin_ia32_femms (void)
v8qi __builtin_ia32_pavgusb (v8qi, v8qi)
v2si __builtin_ia32_pf2id (v2sf)
v2sf __builtin_ia32_pfacc (v2sf, v2sf)
v2sf __builtin_ia32_pfadd (v2sf, v2sf)
v2si __builtin_ia32_pfcmpeq (v2sf, v2sf)
v2si __builtin_ia32_pfcmpge (v2sf, v2sf)
v2si __builtin_ia32_pfcmpgt (v2sf, v2sf)
v2sf __builtin_ia32_pfmax (v2sf, v2sf)
v2sf __builtin_ia32_pfmin (v2sf, v2sf)
v2sf __builtin_ia32_pfmul (v2sf, v2sf)
v2sf __builtin_ia32_pfrcp (v2sf)
v2sf __builtin_ia32_pfrcpit1 (v2sf, v2sf)
v2sf __builtin_ia32_pfrcpit2 (v2sf, v2sf)
v2sf __builtin_ia32_pfrsqrt (v2sf)
v2sf __builtin_ia32_pfrsqrtit1 (v2sf, v2sf)
v2sf __builtin_ia32_pfsub (v2sf, v2sf)
v2sf __builtin_ia32_pfsubr (v2sf, v2sf)
v2sf __builtin_ia32_pi2fd (v2si)
v4hi __builtin_ia32_pmulhrw (v4hi, v4hi)
The following built-in functions are available when both -m3dnow and -march=athlon are used. All of them generate the machine instruction that is part of the name.
v2si __builtin_ia32_pf2iw (v2sf)
v2sf __builtin_ia32_pfnacc (v2sf, v2sf)
v2sf __builtin_ia32_pfpnacc (v2sf, v2sf)
v2sf __builtin_ia32_pi2fw (v2si)
v2sf __builtin_ia32_pswapdsf (v2sf)
v2si __builtin_ia32_pswapdsi (v2si)
The MIPS DSP Application-Specific Extension (ASE) includes new instructions that are designed to improve the performance of DSP and media applications. It provides instructions that operate on packed 8-bit/16-bit integer data, Q7, Q15 and Q31 fractional data.
GCC supports MIPS DSP operations using both the generic vector extensions (see Vector Extensions) and a collection of MIPS-specific built-in functions. Both kinds of support are enabled by the -mdsp command-line option.
Revision 2 of the ASE was introduced in the second half of 2006. This revision adds extra instructions to the original ASE, but is otherwise backwards-compatible with it. You can select revision 2 using the command-line option -mdspr2; this option implies -mdsp.
The SCOUNT and POS bits of the DSP control register are global. The WRDSP, EXTPDP, EXTPDPV and MTHLIP instructions modify the SCOUNT and POS bits. During optimization, the compiler will not delete these instructions and it will not delete calls to functions containing these instructions.
At present, GCC only provides support for operations on 32-bit
vectors. The vector type associated with 8-bit integer data is
usually called v4i8, the vector type associated with Q7
is usually called v4q7, the vector type associated with 16-bit
integer data is usually called v2i16, and the vector type
associated with Q15 is usually called v2q15. They can be
defined in C as follows:
typedef signed char v4i8 __attribute__ ((vector_size(4)));
typedef signed char v4q7 __attribute__ ((vector_size(4)));
typedef short v2i16 __attribute__ ((vector_size(4)));
typedef short v2q15 __attribute__ ((vector_size(4)));
v4i8, v4q7, v2i16 and v2q15 values are
initialized in the same way as aggregates. For example:
v4i8 a = {1, 2, 3, 4};
v4i8 b;
b = (v4i8) {5, 6, 7, 8};
v2q15 c = {0x0fcb, 0x3a75};
v2q15 d;
d = (v2q15) {0.1234 * 0x1.0p15, 0.4567 * 0x1.0p15};
Note: The CPU's endianness determines the order in which values
are packed. On little-endian targets, the first value is the least
significant and the last value is the most significant. The opposite
order applies to big-endian targets. For example, the code above will
set the lowest byte of a to 1 on little-endian targets
and 4 on big-endian targets.
Note: Q7, Q15 and Q31 values must be initialized with their integer
representation. As shown in this example, the integer representation
of a Q7 value can be obtained by multiplying the fractional value by
0x1.0p7. The equivalent for Q15 values is to multiply by
0x1.0p15. The equivalent for Q31 values is to multiply by
0x1.0p31.
The table below lists the v4i8 and v2q15 operations for which
hardware support exists. a and b are v4i8 values,
and c and d are v2q15 values.
| C code | MIPS instruction
|
a + b | addu.qb
|
c + d | addq.ph
|
a - b | subu.qb
|
c - d | subq.ph
|
The table below lists the v2i16 operation for which
hardware support exists for the DSP ASE REV 2. e and f are
v2i16 values.
| C code | MIPS instruction
|
e * f | mul.ph
|
It is easier to describe the DSP built-in functions if we first define the following types:
typedef int q31;
typedef int i32;
typedef unsigned int ui32;
typedef long long a64;
q31 and i32 are actually the same as int, but we
use q31 to indicate a Q31 fractional value and i32 to
indicate a 32-bit integer value. Similarly, a64 is the same as
long long, but we use a64 to indicate values that will
be placed in one of the four DSP accumulators ($ac0,
$ac1, $ac2 or $ac3).
Also, some built-in functions prefer or require immediate numbers as parameters, because the corresponding DSP instructions accept both immediate numbers and register operands, or accept immediate numbers only. The immediate parameters are listed as follows.
imm0_3: 0 to 3.
imm0_7: 0 to 7.
imm0_15: 0 to 15.
imm0_31: 0 to 31.
imm0_63: 0 to 63.
imm0_255: 0 to 255.
imm_n32_31: -32 to 31.
imm_n512_511: -512 to 511.
The following built-in functions map directly to a particular MIPS DSP instruction. Please refer to the architecture specification for details on what each instruction does.
v2q15 __builtin_mips_addq_ph (v2q15, v2q15)
v2q15 __builtin_mips_addq_s_ph (v2q15, v2q15)
q31 __builtin_mips_addq_s_w (q31, q31)
v4i8 __builtin_mips_addu_qb (v4i8, v4i8)
v4i8 __builtin_mips_addu_s_qb (v4i8, v4i8)
v2q15 __builtin_mips_subq_ph (v2q15, v2q15)
v2q15 __builtin_mips_subq_s_ph (v2q15, v2q15)
q31 __builtin_mips_subq_s_w (q31, q31)
v4i8 __builtin_mips_subu_qb (v4i8, v4i8)
v4i8 __builtin_mips_subu_s_qb (v4i8, v4i8)
i32 __builtin_mips_addsc (i32, i32)
i32 __builtin_mips_addwc (i32, i32)
i32 __builtin_mips_modsub (i32, i32)
i32 __builtin_mips_raddu_w_qb (v4i8)
v2q15 __builtin_mips_absq_s_ph (v2q15)
q31 __builtin_mips_absq_s_w (q31)
v4i8 __builtin_mips_precrq_qb_ph (v2q15, v2q15)
v2q15 __builtin_mips_precrq_ph_w (q31, q31)
v2q15 __builtin_mips_precrq_rs_ph_w (q31, q31)
v4i8 __builtin_mips_precrqu_s_qb_ph (v2q15, v2q15)
q31 __builtin_mips_preceq_w_phl (v2q15)
q31 __builtin_mips_preceq_w_phr (v2q15)
v2q15 __builtin_mips_precequ_ph_qbl (v4i8)
v2q15 __builtin_mips_precequ_ph_qbr (v4i8)
v2q15 __builtin_mips_precequ_ph_qbla (v4i8)
v2q15 __builtin_mips_precequ_ph_qbra (v4i8)
v2q15 __builtin_mips_preceu_ph_qbl (v4i8)
v2q15 __builtin_mips_preceu_ph_qbr (v4i8)
v2q15 __builtin_mips_preceu_ph_qbla (v4i8)
v2q15 __builtin_mips_preceu_ph_qbra (v4i8)
v4i8 __builtin_mips_shll_qb (v4i8, imm0_7)
v4i8 __builtin_mips_shll_qb (v4i8, i32)
v2q15 __builtin_mips_shll_ph (v2q15, imm0_15)
v2q15 __builtin_mips_shll_ph (v2q15, i32)
v2q15 __builtin_mips_shll_s_ph (v2q15, imm0_15)
v2q15 __builtin_mips_shll_s_ph (v2q15, i32)
q31 __builtin_mips_shll_s_w (q31, imm0_31)
q31 __builtin_mips_shll_s_w (q31, i32)
v4i8 __builtin_mips_shrl_qb (v4i8, imm0_7)
v4i8 __builtin_mips_shrl_qb (v4i8, i32)
v2q15 __builtin_mips_shra_ph (v2q15, imm0_15)
v2q15 __builtin_mips_shra_ph (v2q15, i32)
v2q15 __builtin_mips_shra_r_ph (v2q15, imm0_15)
v2q15 __builtin_mips_shra_r_ph (v2q15, i32)
q31 __builtin_mips_shra_r_w (q31, imm0_31)
q31 __builtin_mips_shra_r_w (q31, i32)
v2q15 __builtin_mips_muleu_s_ph_qbl (v4i8, v2q15)
v2q15 __builtin_mips_muleu_s_ph_qbr (v4i8, v2q15)
v2q15 __builtin_mips_mulq_rs_ph (v2q15, v2q15)
q31 __builtin_mips_muleq_s_w_phl (v2q15, v2q15)
q31 __builtin_mips_muleq_s_w_phr (v2q15, v2q15)
a64 __builtin_mips_dpau_h_qbl (a64, v4i8, v4i8)
a64 __builtin_mips_dpau_h_qbr (a64, v4i8, v4i8)
a64 __builtin_mips_dpsu_h_qbl (a64, v4i8, v4i8)
a64 __builtin_mips_dpsu_h_qbr (a64, v4i8, v4i8)
a64 __builtin_mips_dpaq_s_w_ph (a64, v2q15, v2q15)
a64 __builtin_mips_dpaq_sa_l_w (a64, q31, q31)
a64 __builtin_mips_dpsq_s_w_ph (a64, v2q15, v2q15)
a64 __builtin_mips_dpsq_sa_l_w (a64, q31, q31)
a64 __builtin_mips_mulsaq_s_w_ph (a64, v2q15, v2q15)
a64 __builtin_mips_maq_s_w_phl (a64, v2q15, v2q15)
a64 __builtin_mips_maq_s_w_phr (a64, v2q15, v2q15)
a64 __builtin_mips_maq_sa_w_phl (a64, v2q15, v2q15)
a64 __builtin_mips_maq_sa_w_phr (a64, v2q15, v2q15)
i32 __builtin_mips_bitrev (i32)
i32 __builtin_mips_insv (i32, i32)
v4i8 __builtin_mips_repl_qb (imm0_255)
v4i8 __builtin_mips_repl_qb (i32)
v2q15 __builtin_mips_repl_ph (imm_n512_511)
v2q15 __builtin_mips_repl_ph (i32)
void __builtin_mips_cmpu_eq_qb (v4i8, v4i8)
void __builtin_mips_cmpu_lt_qb (v4i8, v4i8)
void __builtin_mips_cmpu_le_qb (v4i8, v4i8)
i32 __builtin_mips_cmpgu_eq_qb (v4i8, v4i8)
i32 __builtin_mips_cmpgu_lt_qb (v4i8, v4i8)
i32 __builtin_mips_cmpgu_le_qb (v4i8, v4i8)
void __builtin_mips_cmp_eq_ph (v2q15, v2q15)
void __builtin_mips_cmp_lt_ph (v2q15, v2q15)
void __builtin_mips_cmp_le_ph (v2q15, v2q15)
v4i8 __builtin_mips_pick_qb (v4i8, v4i8)
v2q15 __builtin_mips_pick_ph (v2q15, v2q15)
v2q15 __builtin_mips_packrl_ph (v2q15, v2q15)
i32 __builtin_mips_extr_w (a64, imm0_31)
i32 __builtin_mips_extr_w (a64, i32)
i32 __builtin_mips_extr_r_w (a64, imm0_31)
i32 __builtin_mips_extr_s_h (a64, i32)
i32 __builtin_mips_extr_rs_w (a64, imm0_31)
i32 __builtin_mips_extr_rs_w (a64, i32)
i32 __builtin_mips_extr_s_h (a64, imm0_31)
i32 __builtin_mips_extr_r_w (a64, i32)
i32 __builtin_mips_extp (a64, imm0_31)
i32 __builtin_mips_extp (a64, i32)
i32 __builtin_mips_extpdp (a64, imm0_31)
i32 __builtin_mips_extpdp (a64, i32)
a64 __builtin_mips_shilo (a64, imm_n32_31)
a64 __builtin_mips_shilo (a64, i32)
a64 __builtin_mips_mthlip (a64, i32)
void __builtin_mips_wrdsp (i32, imm0_63)
i32 __builtin_mips_rddsp (imm0_63)
i32 __builtin_mips_lbux (void *, i32)
i32 __builtin_mips_lhx (void *, i32)
i32 __builtin_mips_lwx (void *, i32)
a64 __builtin_mips_ldx (void *, i32) [MIPS64 only]
i32 __builtin_mips_bposge32 (void)
a64 __builtin_mips_madd (a64, i32, i32);
a64 __builtin_mips_maddu (a64, ui32, ui32);
a64 __builtin_mips_msub (a64, i32, i32);
a64 __builtin_mips_msubu (a64, ui32, ui32);
a64 __builtin_mips_mult (i32, i32);
a64 __builtin_mips_multu (ui32, ui32);
The following built-in functions map directly to a particular MIPS DSP REV 2 instruction. Please refer to the architecture specification for details on what each instruction does.
v4q7 __builtin_mips_absq_s_qb (v4q7);
v2i16 __builtin_mips_addu_ph (v2i16, v2i16);
v2i16 __builtin_mips_addu_s_ph (v2i16, v2i16);
v4i8 __builtin_mips_adduh_qb (v4i8, v4i8);
v4i8 __builtin_mips_adduh_r_qb (v4i8, v4i8);
i32 __builtin_mips_append (i32, i32, imm0_31);
i32 __builtin_mips_balign (i32, i32, imm0_3);
i32 __builtin_mips_cmpgdu_eq_qb (v4i8, v4i8);
i32 __builtin_mips_cmpgdu_lt_qb (v4i8, v4i8);
i32 __builtin_mips_cmpgdu_le_qb (v4i8, v4i8);
a64 __builtin_mips_dpa_w_ph (a64, v2i16, v2i16);
a64 __builtin_mips_dps_w_ph (a64, v2i16, v2i16);
v2i16 __builtin_mips_mul_ph (v2i16, v2i16);
v2i16 __builtin_mips_mul_s_ph (v2i16, v2i16);
q31 __builtin_mips_mulq_rs_w (q31, q31);
v2q15 __builtin_mips_mulq_s_ph (v2q15, v2q15);
q31 __builtin_mips_mulq_s_w (q31, q31);
a64 __builtin_mips_mulsa_w_ph (a64, v2i16, v2i16);
v4i8 __builtin_mips_precr_qb_ph (v2i16, v2i16);
v2i16 __builtin_mips_precr_sra_ph_w (i32, i32, imm0_31);
v2i16 __builtin_mips_precr_sra_r_ph_w (i32, i32, imm0_31);
i32 __builtin_mips_prepend (i32, i32, imm0_31);
v4i8 __builtin_mips_shra_qb (v4i8, imm0_7);
v4i8 __builtin_mips_shra_r_qb (v4i8, imm0_7);
v4i8 __builtin_mips_shra_qb (v4i8, i32);
v4i8 __builtin_mips_shra_r_qb (v4i8, i32);
v2i16 __builtin_mips_shrl_ph (v2i16, imm0_15);
v2i16 __builtin_mips_shrl_ph (v2i16, i32);
v2i16 __builtin_mips_subu_ph (v2i16, v2i16);
v2i16 __builtin_mips_subu_s_ph (v2i16, v2i16);
v4i8 __builtin_mips_subuh_qb (v4i8, v4i8);
v4i8 __builtin_mips_subuh_r_qb (v4i8, v4i8);
v2q15 __builtin_mips_addqh_ph (v2q15, v2q15);
v2q15 __builtin_mips_addqh_r_ph (v2q15, v2q15);
q31 __builtin_mips_addqh_w (q31, q31);
q31 __builtin_mips_addqh_r_w (q31, q31);
v2q15 __builtin_mips_subqh_ph (v2q15, v2q15);
v2q15 __builtin_mips_subqh_r_ph (v2q15, v2q15);
q31 __builtin_mips_subqh_w (q31, q31);
q31 __builtin_mips_subqh_r_w (q31, q31);
a64 __builtin_mips_dpax_w_ph (a64, v2i16, v2i16);
a64 __builtin_mips_dpsx_w_ph (a64, v2i16, v2i16);
a64 __builtin_mips_dpaqx_s_w_ph (a64, v2q15, v2q15);
a64 __builtin_mips_dpaqx_sa_w_ph (a64, v2q15, v2q15);
a64 __builtin_mips_dpsqx_s_w_ph (a64, v2q15, v2q15);
a64 __builtin_mips_dpsqx_sa_w_ph (a64, v2q15, v2q15);
The MIPS64 architecture includes a number of instructions that operate on pairs of single-precision floating-point values. Each pair is packed into a 64-bit floating-point register, with one element being designated the “upper half” and the other being designated the “lower half”.
GCC supports paired-single operations using both the generic vector extensions (see Vector Extensions) and a collection of MIPS-specific built-in functions. Both kinds of support are enabled by the -mpaired-single command-line option.
The vector type associated with paired-single values is usually
called v2sf. It can be defined in C as follows:
typedef float v2sf __attribute__ ((vector_size (8)));
v2sf values are initialized in the same way as aggregates.
For example:
v2sf a = {1.5, 9.1};
v2sf b;
float e, f;
b = (v2sf) {e, f};
Note: The CPU's endianness determines which value is stored in
the upper half of a register and which value is stored in the lower half.
On little-endian targets, the first value is the lower one and the second
value is the upper one. The opposite order applies to big-endian targets.
For example, the code above will set the lower half of a to
1.5 on little-endian targets and 9.1 on big-endian targets.
GCC provides intrinsics to access the SIMD instructions provided by the
ST Microelectronics Loongson-2E and -2F processors. These intrinsics,
available after inclusion of the loongson.h header file,
operate on the following 64-bit vector types:
uint8x8_t, a vector of eight unsigned 8-bit integers;
uint16x4_t, a vector of four unsigned 16-bit integers;
uint32x2_t, a vector of two unsigned 32-bit integers;
int8x8_t, a vector of eight signed 8-bit integers;
int16x4_t, a vector of four signed 16-bit integers;
int32x2_t, a vector of two signed 32-bit integers.
The intrinsics provided are listed below; each is named after the machine instruction to which it corresponds, with suffixes added as appropriate to distinguish intrinsics that expand to the same machine instruction yet have different argument types. Refer to the architecture documentation for a description of the functionality of each instruction.
int16x4_t packsswh (int32x2_t s, int32x2_t t);
int8x8_t packsshb (int16x4_t s, int16x4_t t);
uint8x8_t packushb (uint16x4_t s, uint16x4_t t);
uint32x2_t paddw_u (uint32x2_t s, uint32x2_t t);
uint16x4_t paddh_u (uint16x4_t s, uint16x4_t t);
uint8x8_t paddb_u (uint8x8_t s, uint8x8_t t);
int32x2_t paddw_s (int32x2_t s, int32x2_t t);
int16x4_t paddh_s (int16x4_t s, int16x4_t t);
int8x8_t paddb_s (int8x8_t s, int8x8_t t);
uint64_t paddd_u (uint64_t s, uint64_t t);
int64_t paddd_s (int64_t s, int64_t t);
int16x4_t paddsh (int16x4_t s, int16x4_t t);
int8x8_t paddsb (int8x8_t s, int8x8_t t);
uint16x4_t paddush (uint16x4_t s, uint16x4_t t);
uint8x8_t paddusb (uint8x8_t s, uint8x8_t t);
uint64_t pandn_ud (uint64_t s, uint64_t t);
uint32x2_t pandn_uw (uint32x2_t s, uint32x2_t t);
uint16x4_t pandn_uh (uint16x4_t s, uint16x4_t t);
uint8x8_t pandn_ub (uint8x8_t s, uint8x8_t t);
int64_t pandn_sd (int64_t s, int64_t t);
int32x2_t pandn_sw (int32x2_t s, int32x2_t t);
int16x4_t pandn_sh (int16x4_t s, int16x4_t t);
int8x8_t pandn_sb (int8x8_t s, int8x8_t t);
uint16x4_t pavgh (uint16x4_t s, uint16x4_t t);
uint8x8_t pavgb (uint8x8_t s, uint8x8_t t);
uint32x2_t pcmpeqw_u (uint32x2_t s, uint32x2_t t);
uint16x4_t pcmpeqh_u (uint16x4_t s, uint16x4_t t);
uint8x8_t pcmpeqb_u (uint8x8_t s, uint8x8_t t);
int32x2_t pcmpeqw_s (int32x2_t s, int32x2_t t);
int16x4_t pcmpeqh_s (int16x4_t s, int16x4_t t);
int8x8_t pcmpeqb_s (int8x8_t s, int8x8_t t);
uint32x2_t pcmpgtw_u (uint32x2_t s, uint32x2_t t);
uint16x4_t pcmpgth_u (uint16x4_t s, uint16x4_t t);
uint8x8_t pcmpgtb_u (uint8x8_t s, uint8x8_t t);
int32x2_t pcmpgtw_s (int32x2_t s, int32x2_t t);
int16x4_t pcmpgth_s (int16x4_t s, int16x4_t t);
int8x8_t pcmpgtb_s (int8x8_t s, int8x8_t t);
uint16x4_t pextrh_u (uint16x4_t s, int field);
int16x4_t pextrh_s (int16x4_t s, int field);
uint16x4_t pinsrh_0_u (uint16x4_t s, uint16x4_t t);
uint16x4_t pinsrh_1_u (uint16x4_t s, uint16x4_t t);
uint16x4_t pinsrh_2_u (uint16x4_t s, uint16x4_t t);
uint16x4_t pinsrh_3_u (uint16x4_t s, uint16x4_t t);
int16x4_t pinsrh_0_s (int16x4_t s, int16x4_t t);
int16x4_t pinsrh_1_s (int16x4_t s, int16x4_t t);
int16x4_t pinsrh_2_s (int16x4_t s, int16x4_t t);
int16x4_t pinsrh_3_s (int16x4_t s, int16x4_t t);
int32x2_t pmaddhw (int16x4_t s, int16x4_t t);
int16x4_t pmaxsh (int16x4_t s, int16x4_t t);
uint8x8_t pmaxub (uint8x8_t s, uint8x8_t t);
int16x4_t pminsh (int16x4_t s, int16x4_t t);
uint8x8_t pminub (uint8x8_t s, uint8x8_t t);
uint8x8_t pmovmskb_u (uint8x8_t s);
int8x8_t pmovmskb_s (int8x8_t s);
uint16x4_t pmulhuh (uint16x4_t s, uint16x4_t t);
int16x4_t pmulhh (int16x4_t s, int16x4_t t);
int16x4_t pmullh (int16x4_t s, int16x4_t t);
int64_t pmuluw (uint32x2_t s, uint32x2_t t);
uint8x8_t pasubub (uint8x8_t s, uint8x8_t t);
uint16x4_t biadd (uint8x8_t s);
uint16x4_t psadbh (uint8x8_t s, uint8x8_t t);
uint16x4_t pshufh_u (uint16x4_t dest, uint16x4_t s, uint8_t order);
int16x4_t pshufh_s (int16x4_t dest, int16x4_t s, uint8_t order);
uint16x4_t psllh_u (uint16x4_t s, uint8_t amount);
int16x4_t psllh_s (int16x4_t s, uint8_t amount);
uint32x2_t psllw_u (uint32x2_t s, uint8_t amount);
int32x2_t psllw_s (int32x2_t s, uint8_t amount);
uint16x4_t psrlh_u (uint16x4_t s, uint8_t amount);
int16x4_t psrlh_s (int16x4_t s, uint8_t amount);
uint32x2_t psrlw_u (uint32x2_t s, uint8_t amount);
int32x2_t psrlw_s (int32x2_t s, uint8_t amount);
uint16x4_t psrah_u (uint16x4_t s, uint8_t amount);
int16x4_t psrah_s (int16x4_t s, uint8_t amount);
uint32x2_t psraw_u (uint32x2_t s, uint8_t amount);
int32x2_t psraw_s (int32x2_t s, uint8_t amount);
uint32x2_t psubw_u (uint32x2_t s, uint32x2_t t);
uint16x4_t psubh_u (uint16x4_t s, uint16x4_t t);
uint8x8_t psubb_u (uint8x8_t s, uint8x8_t t);
int32x2_t psubw_s (int32x2_t s, int32x2_t t);
int16x4_t psubh_s (int16x4_t s, int16x4_t t);
int8x8_t psubb_s (int8x8_t s, int8x8_t t);
uint64_t psubd_u (uint64_t s, uint64_t t);
int64_t psubd_s (int64_t s, int64_t t);
int16x4_t psubsh (int16x4_t s, int16x4_t t);
int8x8_t psubsb (int8x8_t s, int8x8_t t);
uint16x4_t psubush (uint16x4_t s, uint16x4_t t);
uint8x8_t psubusb (uint8x8_t s, uint8x8_t t);
uint32x2_t punpckhwd_u (uint32x2_t s, uint32x2_t t);
uint16x4_t punpckhhw_u (uint16x4_t s, uint16x4_t t);
uint8x8_t punpckhbh_u (uint8x8_t s, uint8x8_t t);
int32x2_t punpckhwd_s (int32x2_t s, int32x2_t t);
int16x4_t punpckhhw_s (int16x4_t s, int16x4_t t);
int8x8_t punpckhbh_s (int8x8_t s, int8x8_t t);
uint32x2_t punpcklwd_u (uint32x2_t s, uint32x2_t t);
uint16x4_t punpcklhw_u (uint16x4_t s, uint16x4_t t);
uint8x8_t punpcklbh_u (uint8x8_t s, uint8x8_t t);
int32x2_t punpcklwd_s (int32x2_t s, int32x2_t t);
int16x4_t punpcklhw_s (int16x4_t s, int16x4_t t);
int8x8_t punpcklbh_s (int8x8_t s, int8x8_t t);
The table below lists the v2sf operations for which hardware
support exists. a, b and c are v2sf
values and x is an integral value.
| C code | MIPS instruction
|
a + b | add.ps
|
a - b | sub.ps
|
-a | neg.ps
|
a * b | mul.ps
|
a * b + c | madd.ps
|
a * b - c | msub.ps
|
-(a * b + c) | nmadd.ps
|
-(a * b - c) | nmsub.ps
|
x ? a : b | movn.ps/movz.ps
|
Note that the multiply-accumulate instructions can be disabled
using the command-line option -mno-fused-madd.
The following paired-single functions map directly to a particular MIPS instruction. Please refer to the architecture specification for details on what each instruction does.
v2sf __builtin_mips_pll_ps (v2sf, v2sf)pll.ps).
v2sf __builtin_mips_pul_ps (v2sf, v2sf)pul.ps).
v2sf __builtin_mips_plu_ps (v2sf, v2sf)plu.ps).
v2sf __builtin_mips_puu_ps (v2sf, v2sf)puu.ps).
v2sf __builtin_mips_cvt_ps_s (float, float)cvt.ps.s).
float __builtin_mips_cvt_s_pl (v2sf)cvt.s.pl).
float __builtin_mips_cvt_s_pu (v2sf)cvt.s.pu).
v2sf __builtin_mips_abs_ps (v2sf)abs.ps).
v2sf __builtin_mips_alnv_ps (v2sf, v2sf, int)alnv.ps).
Note: The value of the third parameter must be 0 or 4 modulo 8, otherwise the result will be unpredictable. Please read the instruction description for details.
The following multi-instruction functions are also available.
In each case, cond can be any of the 16 floating-point conditions:
f, un, eq, ueq, olt, ult,
ole, ule, sf, ngle, seq, ngl,
lt, nge, le or ngt.
v2sf __builtin_mips_movt_c_cond_ps (v2sf a, v2sf b, v2sf c, v2sf d)v2sf __builtin_mips_movf_c_cond_ps (v2sf a, v2sf b, v2sf c, v2sf d)c.cond.ps,
movt.ps/movf.ps).
The movt functions return the value x computed by:
c.cond.ps cc,a,b
mov.ps x,c
movt.ps x,d,cc
The movf functions are similar but use movf.ps instead
of movt.ps.
int __builtin_mips_upper_c_cond_ps (v2sf a, v2sf b)int __builtin_mips_lower_c_cond_ps (v2sf a, v2sf b)c.cond.ps,
bc1t/bc1f).
These functions compare a and b using c.cond.ps
and return either the upper or lower half of the result. For example:
v2sf a, b;
if (__builtin_mips_upper_c_eq_ps (a, b))
upper_halves_are_equal ();
else
upper_halves_are_unequal ();
if (__builtin_mips_lower_c_eq_ps (a, b))
lower_halves_are_equal ();
else
lower_halves_are_unequal ();
The MIPS-3D Application-Specific Extension (ASE) includes additional paired-single instructions that are designed to improve the performance of 3D graphics operations. Support for these instructions is controlled by the -mips3d command-line option.
The functions listed below map directly to a particular MIPS-3D instruction. Please refer to the architecture specification for more details on what each instruction does.
v2sf __builtin_mips_addr_ps (v2sf, v2sf)addr.ps).
v2sf __builtin_mips_mulr_ps (v2sf, v2sf)mulr.ps).
v2sf __builtin_mips_cvt_pw_ps (v2sf)cvt.pw.ps).
v2sf __builtin_mips_cvt_ps_pw (v2sf)cvt.ps.pw).
float __builtin_mips_recip1_s (float)double __builtin_mips_recip1_d (double)v2sf __builtin_mips_recip1_ps (v2sf)recip1.fmt).
float __builtin_mips_recip2_s (float, float)double __builtin_mips_recip2_d (double, double)v2sf __builtin_mips_recip2_ps (v2sf, v2sf)recip2.fmt).
float __builtin_mips_rsqrt1_s (float)double __builtin_mips_rsqrt1_d (double)v2sf __builtin_mips_rsqrt1_ps (v2sf)rsqrt1.fmt).
float __builtin_mips_rsqrt2_s (float, float)double __builtin_mips_rsqrt2_d (double, double)v2sf __builtin_mips_rsqrt2_ps (v2sf, v2sf)rsqrt2.fmt).
The following multi-instruction functions are also available.
In each case, cond can be any of the 16 floating-point conditions:
f, un, eq, ueq, olt, ult,
ole, ule, sf, ngle, seq,
ngl, lt, nge, le or ngt.
int __builtin_mips_cabs_cond_s (float a, float b)int __builtin_mips_cabs_cond_d (double a, double b)cabs.cond.fmt,
bc1t/bc1f).
These functions compare a and b using cabs.cond.s
or cabs.cond.d and return the result as a boolean value.
For example:
float a, b;
if (__builtin_mips_cabs_eq_s (a, b))
true ();
else
false ();
int __builtin_mips_upper_cabs_cond_ps (v2sf a, v2sf b)int __builtin_mips_lower_cabs_cond_ps (v2sf a, v2sf b)cabs.cond.ps,
bc1t/bc1f).
These functions compare a and b using cabs.cond.ps
and return either the upper or lower half of the result. For example:
v2sf a, b;
if (__builtin_mips_upper_cabs_eq_ps (a, b))
upper_halves_are_equal ();
else
upper_halves_are_unequal ();
if (__builtin_mips_lower_cabs_eq_ps (a, b))
lower_halves_are_equal ();
else
lower_halves_are_unequal ();
v2sf __builtin_mips_movt_cabs_cond_ps (v2sf a, v2sf b, v2sf c, v2sf d)v2sf __builtin_mips_movf_cabs_cond_ps (v2sf a, v2sf b, v2sf c, v2sf d)cabs.cond.ps,
movt.ps/movf.ps).
The movt functions return the value x computed by:
cabs.cond.ps cc,a,b
mov.ps x,c
movt.ps x,d,cc
The movf functions are similar but use movf.ps instead
of movt.ps.
int __builtin_mips_any_c_cond_ps (v2sf a, v2sf b)int __builtin_mips_all_c_cond_ps (v2sf a, v2sf b)int __builtin_mips_any_cabs_cond_ps (v2sf a, v2sf b)int __builtin_mips_all_cabs_cond_ps (v2sf a, v2sf b)c.cond.ps/cabs.cond.ps,
bc1any2t/bc1any2f).
These functions compare a and b using c.cond.ps
or cabs.cond.ps. The any forms return true if either
result is true and the all forms return true if both results are true.
For example:
v2sf a, b;
if (__builtin_mips_any_c_eq_ps (a, b))
one_is_true ();
else
both_are_false ();
if (__builtin_mips_all_c_eq_ps (a, b))
both_are_true ();
else
one_is_false ();
int __builtin_mips_any_c_cond_4s (v2sf a, v2sf b, v2sf c, v2sf d)int __builtin_mips_all_c_cond_4s (v2sf a, v2sf b, v2sf c, v2sf d)int __builtin_mips_any_cabs_cond_4s (v2sf a, v2sf b, v2sf c, v2sf d)int __builtin_mips_all_cabs_cond_4s (v2sf a, v2sf b, v2sf c, v2sf d)c.cond.ps/cabs.cond.ps,
bc1any4t/bc1any4f).
These functions use c.cond.ps or cabs.cond.ps
to compare a with b and to compare c with d.
The any forms return true if any of the four results are true
and the all forms return true if all four results are true.
For example:
v2sf a, b, c, d;
if (__builtin_mips_any_c_eq_4s (a, b, c, d))
some_are_true ();
else
all_are_false ();
if (__builtin_mips_all_c_eq_4s (a, b, c, d))
all_are_true ();
else
some_are_false ();
GCC provides an interface to selected machine instructions from the picoChip instruction set.
int __builtin_sbc (int value)int __builtin_byteswap (int value)int __builtin_brev (int value)int __builtin_adds (int x, int y)int __builtin_subs (int x, int y)void __builtin_halt (void)GCC provides other MIPS-specific built-in functions:
void __builtin_mips_cache (int op, const volatile void *addr)___GCC_HAVE_BUILTIN_MIPS_CACHE
when this function is available.
GCC provides an interface for the PowerPC family of processors to access
the AltiVec operations described in Motorola's AltiVec Programming
Interface Manual. The interface is made available by including
<altivec.h> and using -maltivec and
-mabi=altivec. The interface supports the following vector
types.
vector unsigned char
vector signed char
vector bool char
vector unsigned short
vector signed short
vector bool short
vector pixel
vector unsigned int
vector signed int
vector bool int
vector float
If -mvsx is used the following additional vector types are implemented.
vector unsigned long
vector signed long
vector double
The long types are only implemented for 64-bit code generation, and the long type is only used in the floating point/integer conversion instructions.
GCC's implementation of the high-level language interface available from C and C++ code differs from Motorola's documentation in several ways.
signed or unsigned is omitted, the signedness of the
vector type is the default signedness of the base type. The default
varies depending on the operating system, so a portable program should
always specify the signedness.
__vector,
vector, __pixel, pixel, __bool and
bool. When compiling ISO C, the context-sensitive substitution
of the keywords vector, pixel and bool is
disabled. To use them, you must include <altivec.h> instead.
typedef name as the type specifier for a
vector type.
vec_add ((vector signed int){1, 2, 3, 4}, foo);
Since vec_add is a macro, the vector constant in the example
is treated as four separate arguments. Wrap the entire argument in
parentheses for this to work.
Note: Only the <altivec.h> interface is supported.
Internally, GCC uses built-in functions to achieve the functionality in
the aforementioned header file, but they are not supported and are
subject to change without notice.
The following interfaces are supported for the generic and specific AltiVec operations and the AltiVec predicates. In cases where there is a direct mapping between generic and specific operations, only the generic names are shown here, although the specific operations can also be used.
Arguments that are documented as const int require literal
integral values within the range required for that operation.
vector signed char vec_abs (vector signed char);
vector signed short vec_abs (vector signed short);
vector signed int vec_abs (vector signed int);
vector float vec_abs (vector float);
vector signed char vec_abss (vector signed char);
vector signed short vec_abss (vector signed short);
vector signed int vec_abss (vector signed int);
vector signed char vec_add (vector bool char, vector signed char);
vector signed char vec_add (vector signed char, vector bool char);
vector signed char vec_add (vector signed char, vector signed char);
vector unsigned char vec_add (vector bool char, vector unsigned char);
vector unsigned char vec_add (vector unsigned char, vector bool char);
vector unsigned char vec_add (vector unsigned char,
vector unsigned char);
vector signed short vec_add (vector bool short, vector signed short);
vector signed short vec_add (vector signed short, vector bool short);
vector signed short vec_add (vector signed short, vector signed short);
vector unsigned short vec_add (vector bool short,
vector unsigned short);
vector unsigned short vec_add (vector unsigned short,
vector bool short);
vector unsigned short vec_add (vector unsigned short,
vector unsigned short);
vector signed int vec_add (vector bool int, vector signed int);
vector signed int vec_add (vector signed int, vector bool int);
vector signed int vec_add (vector signed int, vector signed int);
vector unsigned int vec_add (vector bool int, vector unsigned int);
vector unsigned int vec_add (vector unsigned int, vector bool int);
vector unsigned int vec_add (vector unsigned int, vector unsigned int);
vector float vec_add (vector float, vector float);
vector float vec_vaddfp (vector float, vector float);
vector signed int vec_vadduwm (vector bool int, vector signed int);
vector signed int vec_vadduwm (vector signed int, vector bool int);
vector signed int vec_vadduwm (vector signed int, vector signed int);
vector unsigned int vec_vadduwm (vector bool int, vector unsigned int);
vector unsigned int vec_vadduwm (vector unsigned int, vector bool int);
vector unsigned int vec_vadduwm (vector unsigned int,
vector unsigned int);
vector signed short vec_vadduhm (vector bool short,
vector signed short);
vector signed short vec_vadduhm (vector signed short,
vector bool short);
vector signed short vec_vadduhm (vector signed short,
vector signed short);
vector unsigned short vec_vadduhm (vector bool short,
vector unsigned short);
vector unsigned short vec_vadduhm (vector unsigned short,
vector bool short);
vector unsigned short vec_vadduhm (vector unsigned short,
vector unsigned short);
vector signed char vec_vaddubm (vector bool char, vector signed char);
vector signed char vec_vaddubm (vector signed char, vector bool char);
vector signed char vec_vaddubm (vector signed char, vector signed char);
vector unsigned char vec_vaddubm (vector bool char,
vector unsigned char);
vector unsigned char vec_vaddubm (vector unsigned char,
vector bool char);
vector unsigned char vec_vaddubm (vector unsigned char,
vector unsigned char);
vector unsigned int vec_addc (vector unsigned int, vector unsigned int);
vector unsigned char vec_adds (vector bool char, vector unsigned char);
vector unsigned char vec_adds (vector unsigned char, vector bool char);
vector unsigned char vec_adds (vector unsigned char,
vector unsigned char);
vector signed char vec_adds (vector bool char, vector signed char);
vector signed char vec_adds (vector signed char, vector bool char);
vector signed char vec_adds (vector signed char, vector signed char);
vector unsigned short vec_adds (vector bool short,
vector unsigned short);
vector unsigned short vec_adds (vector unsigned short,
vector bool short);
vector unsigned short vec_adds (vector unsigned short,
vector unsigned short);
vector signed short vec_adds (vector bool short, vector signed short);
vector signed short vec_adds (vector signed short, vector bool short);
vector signed short vec_adds (vector signed short, vector signed short);
vector unsigned int vec_adds (vector bool int, vector unsigned int);
vector unsigned int vec_adds (vector unsigned int, vector bool int);
vector unsigned int vec_adds (vector unsigned int, vector unsigned int);
vector signed int vec_adds (vector bool int, vector signed int);
vector signed int vec_adds (vector signed int, vector bool int);
vector signed int vec_adds (vector signed int, vector signed int);
vector signed int vec_vaddsws (vector bool int, vector signed int);
vector signed int vec_vaddsws (vector signed int, vector bool int);
vector signed int vec_vaddsws (vector signed int, vector signed int);
vector unsigned int vec_vadduws (vector bool int, vector unsigned int);
vector unsigned int vec_vadduws (vector unsigned int, vector bool int);
vector unsigned int vec_vadduws (vector unsigned int,
vector unsigned int);
vector signed short vec_vaddshs (vector bool short,
vector signed short);
vector signed short vec_vaddshs (vector signed short,
vector bool short);
vector signed short vec_vaddshs (vector signed short,
vector signed short);
vector unsigned short vec_vadduhs (vector bool short,
vector unsigned short);
vector unsigned short vec_vadduhs (vector unsigned short,
vector bool short);
vector unsigned short vec_vadduhs (vector unsigned short,
vector unsigned short);
vector signed char vec_vaddsbs (vector bool char, vector signed char);
vector signed char vec_vaddsbs (vector signed char, vector bool char);
vector signed char vec_vaddsbs (vector signed char, vector signed char);
vector unsigned char vec_vaddubs (vector bool char,
vector unsigned char);
vector unsigned char vec_vaddubs (vector unsigned char,
vector bool char);
vector unsigned char vec_vaddubs (vector unsigned char,
vector unsigned char);
vector float vec_and (vector float, vector float);
vector float vec_and (vector float, vector bool int);
vector float vec_and (vector bool int, vector float);
vector bool int vec_and (vector bool int, vector bool int);
vector signed int vec_and (vector bool int, vector signed int);
vector signed int vec_and (vector signed int, vector bool int);
vector signed int vec_and (vector signed int, vector signed int);
vector unsigned int vec_and (vector bool int, vector unsigned int);
vector unsigned int vec_and (vector unsigned int, vector bool int);
vector unsigned int vec_and (vector unsigned int, vector unsigned int);
vector bool short vec_and (vector bool short, vector bool short);
vector signed short vec_and (vector bool short, vector signed short);
vector signed short vec_and (vector signed short, vector bool short);
vector signed short vec_and (vector signed short, vector signed short);
vector unsigned short vec_and (vector bool short,
vector unsigned short);
vector unsigned short vec_and (vector unsigned short,
vector bool short);
vector unsigned short vec_and (vector unsigned short,
vector unsigned short);
vector signed char vec_and (vector bool char, vector signed char);
vector bool char vec_and (vector bool char, vector bool char);
vector signed char vec_and (vector signed char, vector bool char);
vector signed char vec_and (vector signed char, vector signed char);
vector unsigned char vec_and (vector bool char, vector unsigned char);
vector unsigned char vec_and (vector unsigned char, vector bool char);
vector unsigned char vec_and (vector unsigned char,
vector unsigned char);
vector float vec_andc (vector float, vector float);
vector float vec_andc (vector float, vector bool int);
vector float vec_andc (vector bool int, vector float);
vector bool int vec_andc (vector bool int, vector bool int);
vector signed int vec_andc (vector bool int, vector signed int);
vector signed int vec_andc (vector signed int, vector bool int);
vector signed int vec_andc (vector signed int, vector signed int);
vector unsigned int vec_andc (vector bool int, vector unsigned int);
vector unsigned int vec_andc (vector unsigned int, vector bool int);
vector unsigned int vec_andc (vector unsigned int, vector unsigned int);
vector bool short vec_andc (vector bool short, vector bool short);
vector signed short vec_andc (vector bool short, vector signed short);
vector signed short vec_andc (vector signed short, vector bool short);
vector signed short vec_andc (vector signed short, vector signed short);
vector unsigned short vec_andc (vector bool short,
vector unsigned short);
vector unsigned short vec_andc (vector unsigned short,
vector bool short);
vector unsigned short vec_andc (vector unsigned short,
vector unsigned short);
vector signed char vec_andc (vector bool char, vector signed char);
vector bool char vec_andc (vector bool char, vector bool char);
vector signed char vec_andc (vector signed char, vector bool char);
vector signed char vec_andc (vector signed char, vector signed char);
vector unsigned char vec_andc (vector bool char, vector unsigned char);
vector unsigned char vec_andc (vector unsigned char, vector bool char);
vector unsigned char vec_andc (vector unsigned char,
vector unsigned char);
vector unsigned char vec_avg (vector unsigned char,
vector unsigned char);
vector signed char vec_avg (vector signed char, vector signed char);
vector unsigned short vec_avg (vector unsigned short,
vector unsigned short);
vector signed short vec_avg (vector signed short, vector signed short);
vector unsigned int vec_avg (vector unsigned int, vector unsigned int);
vector signed int vec_avg (vector signed int, vector signed int);
vector signed int vec_vavgsw (vector signed int, vector signed int);
vector unsigned int vec_vavguw (vector unsigned int,
vector unsigned int);
vector signed short vec_vavgsh (vector signed short,
vector signed short);
vector unsigned short vec_vavguh (vector unsigned short,
vector unsigned short);
vector signed char vec_vavgsb (vector signed char, vector signed char);
vector unsigned char vec_vavgub (vector unsigned char,
vector unsigned char);
vector float vec_copysign (vector float);
vector float vec_ceil (vector float);
vector signed int vec_cmpb (vector float, vector float);
vector bool char vec_cmpeq (vector signed char, vector signed char);
vector bool char vec_cmpeq (vector unsigned char, vector unsigned char);
vector bool short vec_cmpeq (vector signed short, vector signed short);
vector bool short vec_cmpeq (vector unsigned short,
vector unsigned short);
vector bool int vec_cmpeq (vector signed int, vector signed int);
vector bool int vec_cmpeq (vector unsigned int, vector unsigned int);
vector bool int vec_cmpeq (vector float, vector float);
vector bool int vec_vcmpeqfp (vector float, vector float);
vector bool int vec_vcmpequw (vector signed int, vector signed int);
vector bool int vec_vcmpequw (vector unsigned int, vector unsigned int);
vector bool short vec_vcmpequh (vector signed short,
vector signed short);
vector bool short vec_vcmpequh (vector unsigned short,
vector unsigned short);
vector bool char vec_vcmpequb (vector signed char, vector signed char);
vector bool char vec_vcmpequb (vector unsigned char,
vector unsigned char);
vector bool int vec_cmpge (vector float, vector float);
vector bool char vec_cmpgt (vector unsigned char, vector unsigned char);
vector bool char vec_cmpgt (vector signed char, vector signed char);
vector bool short vec_cmpgt (vector unsigned short,
vector unsigned short);
vector bool short vec_cmpgt (vector signed short, vector signed short);
vector bool int vec_cmpgt (vector unsigned int, vector unsigned int);
vector bool int vec_cmpgt (vector signed int, vector signed int);
vector bool int vec_cmpgt (vector float, vector float);
vector bool int vec_vcmpgtfp (vector float, vector float);
vector bool int vec_vcmpgtsw (vector signed int, vector signed int);
vector bool int vec_vcmpgtuw (vector unsigned int, vector unsigned int);
vector bool short vec_vcmpgtsh (vector signed short,
vector signed short);
vector bool short vec_vcmpgtuh (vector unsigned short,
vector unsigned short);
vector bool char vec_vcmpgtsb (vector signed char, vector signed char);
vector bool char vec_vcmpgtub (vector unsigned char,
vector unsigned char);
vector bool int vec_cmple (vector float, vector float);
vector bool char vec_cmplt (vector unsigned char, vector unsigned char);
vector bool char vec_cmplt (vector signed char, vector signed char);
vector bool short vec_cmplt (vector unsigned short,
vector unsigned short);
vector bool short vec_cmplt (vector signed short, vector signed short);
vector bool int vec_cmplt (vector unsigned int, vector unsigned int);
vector bool int vec_cmplt (vector signed int, vector signed int);
vector bool int vec_cmplt (vector float, vector float);
vector float vec_ctf (vector unsigned int, const int);
vector float vec_ctf (vector signed int, const int);
vector float vec_vcfsx (vector signed int, const int);
vector float vec_vcfux (vector unsigned int, const int);
vector signed int vec_cts (vector float, const int);
vector unsigned int vec_ctu (vector float, const int);
void vec_dss (const int);
void vec_dssall (void);
void vec_dst (const vector unsigned char *, int, const int);
void vec_dst (const vector signed char *, int, const int);
void vec_dst (const vector bool char *, int, const int);
void vec_dst (const vector unsigned short *, int, const int);
void vec_dst (const vector signed short *, int, const int);
void vec_dst (const vector bool short *, int, const int);
void vec_dst (const vector pixel *, int, const int);
void vec_dst (const vector unsigned int *, int, const int);
void vec_dst (const vector signed int *, int, const int);
void vec_dst (const vector bool int *, int, const int);
void vec_dst (const vector float *, int, const int);
void vec_dst (const unsigned char *, int, const int);
void vec_dst (const signed char *, int, const int);
void vec_dst (const unsigned short *, int, const int);
void vec_dst (const short *, int, const int);
void vec_dst (const unsigned int *, int, const int);
void vec_dst (const int *, int, const int);
void vec_dst (const unsigned long *, int, const int);
void vec_dst (const long *, int, const int);
void vec_dst (const float *, int, const int);
void vec_dstst (const vector unsigned char *, int, const int);
void vec_dstst (const vector signed char *, int, const int);
void vec_dstst (const vector bool char *, int, const int);
void vec_dstst (const vector unsigned short *, int, const int);
void vec_dstst (const vector signed short *, int, const int);
void vec_dstst (const vector bool short *, int, const int);
void vec_dstst (const vector pixel *, int, const int);
void vec_dstst (const vector unsigned int *, int, const int);
void vec_dstst (const vector signed int *, int, const int);
void vec_dstst (const vector bool int *, int, const int);
void vec_dstst (const vector float *, int, const int);
void vec_dstst (const unsigned char *, int, const int);
void vec_dstst (const signed char *, int, const int);
void vec_dstst (const unsigned short *, int, const int);
void vec_dstst (const short *, int, const int);
void vec_dstst (const unsigned int *, int, const int);
void vec_dstst (const int *, int, const int);
void vec_dstst (const unsigned long *, int, const int);
void vec_dstst (const long *, int, const int);
void vec_dstst (const float *, int, const int);
void vec_dststt (const vector unsigned char *, int, const int);
void vec_dststt (const vector signed char *, int, const int);
void vec_dststt (const vector bool char *, int, const int);
void vec_dststt (const vector unsigned short *, int, const int);
void vec_dststt (const vector signed short *, int, const int);
void vec_dststt (const vector bool short *, int, const int);
void vec_dststt (const vector pixel *, int, const int);
void vec_dststt (const vector unsigned int *, int, const int);
void vec_dststt (const vector signed int *, int, const int);
void vec_dststt (const vector bool int *, int, const int);
void vec_dststt (const vector float *, int, const int);
void vec_dststt (const unsigned char *, int, const int);
void vec_dststt (const signed char *, int, const int);
void vec_dststt (const unsigned short *, int, const int);
void vec_dststt (const short *, int, const int);
void vec_dststt (const unsigned int *, int, const int);
void vec_dststt (const int *, int, const int);
void vec_dststt (const unsigned long *, int, const int);
void vec_dststt (const long *, int, const int);
void vec_dststt (const float *, int, const int);
void vec_dstt (const vector unsigned char *, int, const int);
void vec_dstt (const vector signed char *, int, const int);
void vec_dstt (const vector bool char *, int, const int);
void vec_dstt (const vector unsigned short *, int, const int);
void vec_dstt (const vector signed short *, int, const int);
void vec_dstt (const vector bool short *, int, const int);
void vec_dstt (const vector pixel *, int, const int);
void vec_dstt (const vector unsigned int *, int, const int);
void vec_dstt (const vector signed int *, int, const int);
void vec_dstt (const vector bool int *, int, const int);
void vec_dstt (const vector float *, int, const int);
void vec_dstt (const unsigned char *, int, const int);
void vec_dstt (const signed char *, int, const int);
void vec_dstt (const unsigned short *, int, const int);
void vec_dstt (const short *, int, const int);
void vec_dstt (const unsigned int *, int, const int);
void vec_dstt (const int *, int, const int);
void vec_dstt (const unsigned long *, int, const int);
void vec_dstt (const long *, int, const int);
void vec_dstt (const float *, int, const int);
vector float vec_expte (vector float);
vector float vec_floor (vector float);
vector float vec_ld (int, const vector float *);
vector float vec_ld (int, const float *);
vector bool int vec_ld (int, const vector bool int *);
vector signed int vec_ld (int, const vector signed int *);
vector signed int vec_ld (int, const int *);
vector signed int vec_ld (int, const long *);
vector unsigned int vec_ld (int, const vector unsigned int *);
vector unsigned int vec_ld (int, const unsigned int *);
vector unsigned int vec_ld (int, const unsigned long *);
vector bool short vec_ld (int, const vector bool short *);
vector pixel vec_ld (int, const vector pixel *);
vector signed short vec_ld (int, const vector signed short *);
vector signed short vec_ld (int, const short *);
vector unsigned short vec_ld (int, const vector unsigned short *);
vector unsigned short vec_ld (int, const unsigned short *);
vector bool char vec_ld (int, const vector bool char *);
vector signed char vec_ld (int, const vector signed char *);
vector signed char vec_ld (int, const signed char *);
vector unsigned char vec_ld (int, const vector unsigned char *);
vector unsigned char vec_ld (int, const unsigned char *);
vector signed char vec_lde (int, const signed char *);
vector unsigned char vec_lde (int, const unsigned char *);
vector signed short vec_lde (int, const short *);
vector unsigned short vec_lde (int, const unsigned short *);
vector float vec_lde (int, const float *);
vector signed int vec_lde (int, const int *);
vector unsigned int vec_lde (int, const unsigned int *);
vector signed int vec_lde (int, const long *);
vector unsigned int vec_lde (int, const unsigned long *);
vector float vec_lvewx (int, float *);
vector signed int vec_lvewx (int, int *);
vector unsigned int vec_lvewx (int, unsigned int *);
vector signed int vec_lvewx (int, long *);
vector unsigned int vec_lvewx (int, unsigned long *);
vector signed short vec_lvehx (int, short *);
vector unsigned short vec_lvehx (int, unsigned short *);
vector signed char vec_lvebx (int, char *);
vector unsigned char vec_lvebx (int, unsigned char *);
vector float vec_ldl (int, const vector float *);
vector float vec_ldl (int, const float *);
vector bool int vec_ldl (int, const vector bool int *);
vector signed int vec_ldl (int, const vector signed int *);
vector signed int vec_ldl (int, const int *);
vector signed int vec_ldl (int, const long *);
vector unsigned int vec_ldl (int, const vector unsigned int *);
vector unsigned int vec_ldl (int, const unsigned int *);
vector unsigned int vec_ldl (int, const unsigned long *);
vector bool short vec_ldl (int, const vector bool short *);
vector pixel vec_ldl (int, const vector pixel *);
vector signed short vec_ldl (int, const vector signed short *);
vector signed short vec_ldl (int, const short *);
vector unsigned short vec_ldl (int, const vector unsigned short *);
vector unsigned short vec_ldl (int, const unsigned short *);
vector bool char vec_ldl (int, const vector bool char *);
vector signed char vec_ldl (int, const vector signed char *);
vector signed char vec_ldl (int, const signed char *);
vector unsigned char vec_ldl (int, const vector unsigned char *);
vector unsigned char vec_ldl (int, const unsigned char *);
vector float vec_loge (vector float);
vector unsigned char vec_lvsl (int, const volatile unsigned char *);
vector unsigned char vec_lvsl (int, const volatile signed char *);
vector unsigned char vec_lvsl (int, const volatile unsigned short *);
vector unsigned char vec_lvsl (int, const volatile short *);
vector unsigned char vec_lvsl (int, const volatile unsigned int *);
vector unsigned char vec_lvsl (int, const volatile int *);
vector unsigned char vec_lvsl (int, const volatile unsigned long *);
vector unsigned char vec_lvsl (int, const volatile long *);
vector unsigned char vec_lvsl (int, const volatile float *);
vector unsigned char vec_lvsr (int, const volatile unsigned char *);
vector unsigned char vec_lvsr (int, const volatile signed char *);
vector unsigned char vec_lvsr (int, const volatile unsigned short *);
vector unsigned char vec_lvsr (int, const volatile short *);
vector unsigned char vec_lvsr (int, const volatile unsigned int *);
vector unsigned char vec_lvsr (int, const volatile int *);
vector unsigned char vec_lvsr (int, const volatile unsigned long *);
vector unsigned char vec_lvsr (int, const volatile long *);
vector unsigned char vec_lvsr (int, const volatile float *);
vector float vec_madd (vector float, vector float, vector float);
vector signed short vec_madds (vector signed short,
vector signed short,
vector signed short);
vector unsigned char vec_max (vector bool char, vector unsigned char);
vector unsigned char vec_max (vector unsigned char, vector bool char);
vector unsigned char vec_max (vector unsigned char,
vector unsigned char);
vector signed char vec_max (vector bool char, vector signed char);
vector signed char vec_max (vector signed char, vector bool char);
vector signed char vec_max (vector signed char, vector signed char);
vector unsigned short vec_max (vector bool short,
vector unsigned short);
vector unsigned short vec_max (vector unsigned short,
vector bool short);
vector unsigned short vec_max (vector unsigned short,
vector unsigned short);
vector signed short vec_max (vector bool short, vector signed short);
vector signed short vec_max (vector signed short, vector bool short);
vector signed short vec_max (vector signed short, vector signed short);
vector unsigned int vec_max (vector bool int, vector unsigned int);
vector unsigned int vec_max (vector unsigned int, vector bool int);
vector unsigned int vec_max (vector unsigned int, vector unsigned int);
vector signed int vec_max (vector bool int, vector signed int);
vector signed int vec_max (vector signed int, vector bool int);
vector signed int vec_max (vector signed int, vector signed int);
vector float vec_max (vector float, vector float);
vector float vec_vmaxfp (vector float, vector float);
vector signed int vec_vmaxsw (vector bool int, vector signed int);
vector signed int vec_vmaxsw (vector signed int, vector bool int);
vector signed int vec_vmaxsw (vector signed int, vector signed int);
vector unsigned int vec_vmaxuw (vector bool int, vector unsigned int);
vector unsigned int vec_vmaxuw (vector unsigned int, vector bool int);
vector unsigned int vec_vmaxuw (vector unsigned int,
vector unsigned int);
vector signed short vec_vmaxsh (vector bool short, vector signed short);
vector signed short vec_vmaxsh (vector signed short, vector bool short);
vector signed short vec_vmaxsh (vector signed short,
vector signed short);
vector unsigned short vec_vmaxuh (vector bool short,
vector unsigned short);
vector unsigned short vec_vmaxuh (vector unsigned short,
vector bool short);
vector unsigned short vec_vmaxuh (vector unsigned short,
vector unsigned short);
vector signed char vec_vmaxsb (vector bool char, vector signed char);
vector signed char vec_vmaxsb (vector signed char, vector bool char);
vector signed char vec_vmaxsb (vector signed char, vector signed char);
vector unsigned char vec_vmaxub (vector bool char,
vector unsigned char);
vector unsigned char vec_vmaxub (vector unsigned char,
vector bool char);
vector unsigned char vec_vmaxub (vector unsigned char,
vector unsigned char);
vector bool char vec_mergeh (vector bool char, vector bool char);
vector signed char vec_mergeh (vector signed char, vector signed char);
vector unsigned char vec_mergeh (vector unsigned char,
vector unsigned char);
vector bool short vec_mergeh (vector bool short, vector bool short);
vector pixel vec_mergeh (vector pixel, vector pixel);
vector signed short vec_mergeh (vector signed short,
vector signed short);
vector unsigned short vec_mergeh (vector unsigned short,
vector unsigned short);
vector float vec_mergeh (vector float, vector float);
vector bool int vec_mergeh (vector bool int, vector bool int);
vector signed int vec_mergeh (vector signed int, vector signed int);
vector unsigned int vec_mergeh (vector unsigned int,
vector unsigned int);
vector float vec_vmrghw (vector float, vector float);
vector bool int vec_vmrghw (vector bool int, vector bool int);
vector signed int vec_vmrghw (vector signed int, vector signed int);
vector unsigned int vec_vmrghw (vector unsigned int,
vector unsigned int);
vector bool short vec_vmrghh (vector bool short, vector bool short);
vector signed short vec_vmrghh (vector signed short,
vector signed short);
vector unsigned short vec_vmrghh (vector unsigned short,
vector unsigned short);
vector pixel vec_vmrghh (vector pixel, vector pixel);
vector bool char vec_vmrghb (vector bool char, vector bool char);
vector signed char vec_vmrghb (vector signed char, vector signed char);
vector unsigned char vec_vmrghb (vector unsigned char,
vector unsigned char);
vector bool char vec_mergel (vector bool char, vector bool char);
vector signed char vec_mergel (vector signed char, vector signed char);
vector unsigned char vec_mergel (vector unsigned char,
vector unsigned char);
vector bool short vec_mergel (vector bool short, vector bool short);
vector pixel vec_mergel (vector pixel, vector pixel);
vector signed short vec_mergel (vector signed short,
vector signed short);
vector unsigned short vec_mergel (vector unsigned short,
vector unsigned short);
vector float vec_mergel (vector float, vector float);
vector bool int vec_mergel (vector bool int, vector bool int);
vector signed int vec_mergel (vector signed int, vector signed int);
vector unsigned int vec_mergel (vector unsigned int,
vector unsigned int);
vector float vec_vmrglw (vector float, vector float);
vector signed int vec_vmrglw (vector signed int, vector signed int);
vector unsigned int vec_vmrglw (vector unsigned int,
vector unsigned int);
vector bool int vec_vmrglw (vector bool int, vector bool int);
vector bool short vec_vmrglh (vector bool short, vector bool short);
vector signed short vec_vmrglh (vector signed short,
vector signed short);
vector unsigned short vec_vmrglh (vector unsigned short,
vector unsigned short);
vector pixel vec_vmrglh (vector pixel, vector pixel);
vector bool char vec_vmrglb (vector bool char, vector bool char);
vector signed char vec_vmrglb (vector signed char, vector signed char);
vector unsigned char vec_vmrglb (vector unsigned char,
vector unsigned char);
vector unsigned short vec_mfvscr (void);
vector unsigned char vec_min (vector bool char, vector unsigned char);
vector unsigned char vec_min (vector unsigned char, vector bool char);
vector unsigned char vec_min (vector unsigned char,
vector unsigned char);
vector signed char vec_min (vector bool char, vector signed char);
vector signed char vec_min (vector signed char, vector bool char);
vector signed char vec_min (vector signed char, vector signed char);
vector unsigned short vec_min (vector bool short,
vector unsigned short);
vector unsigned short vec_min (vector unsigned short,
vector bool short);
vector unsigned short vec_min (vector unsigned short,
vector unsigned short);
vector signed short vec_min (vector bool short, vector signed short);
vector signed short vec_min (vector signed short, vector bool short);
vector signed short vec_min (vector signed short, vector signed short);
vector unsigned int vec_min (vector bool int, vector unsigned int);
vector unsigned int vec_min (vector unsigned int, vector bool int);
vector unsigned int vec_min (vector unsigned int, vector unsigned int);
vector signed int vec_min (vector bool int, vector signed int);
vector signed int vec_min (vector signed int, vector bool int);
vector signed int vec_min (vector signed int, vector signed int);
vector float vec_min (vector float, vector float);
vector float vec_vminfp (vector float, vector float);
vector signed int vec_vminsw (vector bool int, vector signed int);
vector signed int vec_vminsw (vector signed int, vector bool int);
vector signed int vec_vminsw (vector signed int, vector signed int);
vector unsigned int vec_vminuw (vector bool int, vector unsigned int);
vector unsigned int vec_vminuw (vector unsigned int, vector bool int);
vector unsigned int vec_vminuw (vector unsigned int,
vector unsigned int);
vector signed short vec_vminsh (vector bool short, vector signed short);
vector signed short vec_vminsh (vector signed short, vector bool short);
vector signed short vec_vminsh (vector signed short,
vector signed short);
vector unsigned short vec_vminuh (vector bool short,
vector unsigned short);
vector unsigned short vec_vminuh (vector unsigned short,
vector bool short);
vector unsigned short vec_vminuh (vector unsigned short,
vector unsigned short);
vector signed char vec_vminsb (vector bool char, vector signed char);
vector signed char vec_vminsb (vector signed char, vector bool char);
vector signed char vec_vminsb (vector signed char, vector signed char);
vector unsigned char vec_vminub (vector bool char,
vector unsigned char);
vector unsigned char vec_vminub (vector unsigned char,
vector bool char);
vector unsigned char vec_vminub (vector unsigned char,
vector unsigned char);
vector signed short vec_mladd (vector signed short,
vector signed short,
vector signed short);
vector signed short vec_mladd (vector signed short,
vector unsigned short,
vector unsigned short);
vector signed short vec_mladd (vector unsigned short,
vector signed short,
vector signed short);
vector unsigned short vec_mladd (vector unsigned short,
vector unsigned short,
vector unsigned short);
vector signed short vec_mradds (vector signed short,
vector signed short,
vector signed short);
vector unsigned int vec_msum (vector unsigned char,
vector unsigned char,
vector unsigned int);
vector signed int vec_msum (vector signed char,
vector unsigned char,
vector signed int);
vector unsigned int vec_msum (vector unsigned short,
vector unsigned short,
vector unsigned int);
vector signed int vec_msum (vector signed short,
vector signed short,
vector signed int);
vector signed int vec_vmsumshm (vector signed short,
vector signed short,
vector signed int);
vector unsigned int vec_vmsumuhm (vector unsigned short,
vector unsigned short,
vector unsigned int);
vector signed int vec_vmsummbm (vector signed char,
vector unsigned char,
vector signed int);
vector unsigned int vec_vmsumubm (vector unsigned char,
vector unsigned char,
vector unsigned int);
vector unsigned int vec_msums (vector unsigned short,
vector unsigned short,
vector unsigned int);
vector signed int vec_msums (vector signed short,
vector signed short,
vector signed int);
vector signed int vec_vmsumshs (vector signed short,
vector signed short,
vector signed int);
vector unsigned int vec_vmsumuhs (vector unsigned short,
vector unsigned short,
vector unsigned int);
void vec_mtvscr (vector signed int);
void vec_mtvscr (vector unsigned int);
void vec_mtvscr (vector bool int);
void vec_mtvscr (vector signed short);
void vec_mtvscr (vector unsigned short);
void vec_mtvscr (vector bool short);
void vec_mtvscr (vector pixel);
void vec_mtvscr (vector signed char);
void vec_mtvscr (vector unsigned char);
void vec_mtvscr (vector bool char);
vector unsigned short vec_mule (vector unsigned char,
vector unsigned char);
vector signed short vec_mule (vector signed char,
vector signed char);
vector unsigned int vec_mule (vector unsigned short,
vector unsigned short);
vector signed int vec_mule (vector signed short, vector signed short);
vector signed int vec_vmulesh (vector signed short,
vector signed short);
vector unsigned int vec_vmuleuh (vector unsigned short,
vector unsigned short);
vector signed short vec_vmulesb (vector signed char,
vector signed char);
vector unsigned short vec_vmuleub (vector unsigned char,
vector unsigned char);
vector unsigned short vec_mulo (vector unsigned char,
vector unsigned char);
vector signed short vec_mulo (vector signed char, vector signed char);
vector unsigned int vec_mulo (vector unsigned short,
vector unsigned short);
vector signed int vec_mulo (vector signed short, vector signed short);
vector signed int vec_vmulosh (vector signed short,
vector signed short);
vector unsigned int vec_vmulouh (vector unsigned short,
vector unsigned short);
vector signed short vec_vmulosb (vector signed char,
vector signed char);
vector unsigned short vec_vmuloub (vector unsigned char,
vector unsigned char);
vector float vec_nmsub (vector float, vector float, vector float);
vector float vec_nor (vector float, vector float);
vector signed int vec_nor (vector signed int, vector signed int);
vector unsigned int vec_nor (vector unsigned int, vector unsigned int);
vector bool int vec_nor (vector bool int, vector bool int);
vector signed short vec_nor (vector signed short, vector signed short);
vector unsigned short vec_nor (vector unsigned short,
vector unsigned short);
vector bool short vec_nor (vector bool short, vector bool short);
vector signed char vec_nor (vector signed char, vector signed char);
vector unsigned char vec_nor (vector unsigned char,
vector unsigned char);
vector bool char vec_nor (vector bool char, vector bool char);
vector float vec_or (vector float, vector float);
vector float vec_or (vector float, vector bool int);
vector float vec_or (vector bool int, vector float);
vector bool int vec_or (vector bool int, vector bool int);
vector signed int vec_or (vector bool int, vector signed int);
vector signed int vec_or (vector signed int, vector bool int);
vector signed int vec_or (vector signed int, vector signed int);
vector unsigned int vec_or (vector bool int, vector unsigned int);
vector unsigned int vec_or (vector unsigned int, vector bool int);
vector unsigned int vec_or (vector unsigned int, vector unsigned int);
vector bool short vec_or (vector bool short, vector bool short);
vector signed short vec_or (vector bool short, vector signed short);
vector signed short vec_or (vector signed short, vector bool short);
vector signed short vec_or (vector signed short, vector signed short);
vector unsigned short vec_or (vector bool short, vector unsigned short);
vector unsigned short vec_or (vector unsigned short, vector bool short);
vector unsigned short vec_or (vector unsigned short,
vector unsigned short);
vector signed char vec_or (vector bool char, vector signed char);
vector bool char vec_or (vector bool char, vector bool char);
vector signed char vec_or (vector signed char, vector bool char);
vector signed char vec_or (vector signed char, vector signed char);
vector unsigned char vec_or (vector bool char, vector unsigned char);
vector unsigned char vec_or (vector unsigned char, vector bool char);
vector unsigned char vec_or (vector unsigned char,
vector unsigned char);
vector signed char vec_pack (vector signed short, vector signed short);
vector unsigned char vec_pack (vector unsigned short,
vector unsigned short);
vector bool char vec_pack (vector bool short, vector bool short);
vector signed short vec_pack (vector signed int, vector signed int);
vector unsigned short vec_pack (vector unsigned int,
vector unsigned int);
vector bool short vec_pack (vector bool int, vector bool int);
vector bool short vec_vpkuwum (vector bool int, vector bool int);
vector signed short vec_vpkuwum (vector signed int, vector signed int);
vector unsigned short vec_vpkuwum (vector unsigned int,
vector unsigned int);
vector bool char vec_vpkuhum (vector bool short, vector bool short);
vector signed char vec_vpkuhum (vector signed short,
vector signed short);
vector unsigned char vec_vpkuhum (vector unsigned short,
vector unsigned short);
vector pixel vec_packpx (vector unsigned int, vector unsigned int);
vector unsigned char vec_packs (vector unsigned short,
vector unsigned short);
vector signed char vec_packs (vector signed short, vector signed short);
vector unsigned short vec_packs (vector unsigned int,
vector unsigned int);
vector signed short vec_packs (vector signed int, vector signed int);
vector signed short vec_vpkswss (vector signed int, vector signed int);
vector unsigned short vec_vpkuwus (vector unsigned int,
vector unsigned int);
vector signed char vec_vpkshss (vector signed short,
vector signed short);
vector unsigned char vec_vpkuhus (vector unsigned short,
vector unsigned short);
vector unsigned char vec_packsu (vector unsigned short,
vector unsigned short);
vector unsigned char vec_packsu (vector signed short,
vector signed short);
vector unsigned short vec_packsu (vector unsigned int,
vector unsigned int);
vector unsigned short vec_packsu (vector signed int, vector signed int);
vector unsigned short vec_vpkswus (vector signed int,
vector signed int);
vector unsigned char vec_vpkshus (vector signed short,
vector signed short);
vector float vec_perm (vector float,
vector float,
vector unsigned char);
vector signed int vec_perm (vector signed int,
vector signed int,
vector unsigned char);
vector unsigned int vec_perm (vector unsigned int,
vector unsigned int,
vector unsigned char);
vector bool int vec_perm (vector bool int,
vector bool int,
vector unsigned char);
vector signed short vec_perm (vector signed short,
vector signed short,
vector unsigned char);
vector unsigned short vec_perm (vector unsigned short,
vector unsigned short,
vector unsigned char);
vector bool short vec_perm (vector bool short,
vector bool short,
vector unsigned char);
vector pixel vec_perm (vector pixel,
vector pixel,
vector unsigned char);
vector signed char vec_perm (vector signed char,
vector signed char,
vector unsigned char);
vector unsigned char vec_perm (vector unsigned char,
vector unsigned char,
vector unsigned char);
vector bool char vec_perm (vector bool char,
vector bool char,
vector unsigned char);
vector float vec_re (vector float);
vector signed char vec_rl (vector signed char,
vector unsigned char);
vector unsigned char vec_rl (vector unsigned char,
vector unsigned char);
vector signed short vec_rl (vector signed short, vector unsigned short);
vector unsigned short vec_rl (vector unsigned short,
vector unsigned short);
vector signed int vec_rl (vector signed int, vector unsigned int);
vector unsigned int vec_rl (vector unsigned int, vector unsigned int);
vector signed int vec_vrlw (vector signed int, vector unsigned int);
vector unsigned int vec_vrlw (vector unsigned int, vector unsigned int);
vector signed short vec_vrlh (vector signed short,
vector unsigned short);
vector unsigned short vec_vrlh (vector unsigned short,
vector unsigned short);
vector signed char vec_vrlb (vector signed char, vector unsigned char);
vector unsigned char vec_vrlb (vector unsigned char,
vector unsigned char);
vector float vec_round (vector float);
vector float vec_recip (vector float, vector float);
vector float vec_rsqrt (vector float);
vector float vec_rsqrte (vector float);
vector float vec_sel (vector float, vector float, vector bool int);
vector float vec_sel (vector float, vector float, vector unsigned int);
vector signed int vec_sel (vector signed int,
vector signed int,
vector bool int);
vector signed int vec_sel (vector signed int,
vector signed int,
vector unsigned int);
vector unsigned int vec_sel (vector unsigned int,
vector unsigned int,
vector bool int);
vector unsigned int vec_sel (vector unsigned int,
vector unsigned int,
vector unsigned int);
vector bool int vec_sel (vector bool int,
vector bool int,
vector bool int);
vector bool int vec_sel (vector bool int,
vector bool int,
vector unsigned int);
vector signed short vec_sel (vector signed short,
vector signed short,
vector bool short);
vector signed short vec_sel (vector signed short,
vector signed short,
vector unsigned short);
vector unsigned short vec_sel (vector unsigned short,
vector unsigned short,
vector bool short);
vector unsigned short vec_sel (vector unsigned short,
vector unsigned short,
vector unsigned short);
vector bool short vec_sel (vector bool short,
vector bool short,
vector bool short);
vector bool short vec_sel (vector bool short,
vector bool short,
vector unsigned short);
vector signed char vec_sel (vector signed char,
vector signed char,
vector bool char);
vector signed char vec_sel (vector signed char,
vector signed char,
vector unsigned char);
vector unsigned char vec_sel (vector unsigned char,
vector unsigned char,
vector bool char);
vector unsigned char vec_sel (vector unsigned char,
vector unsigned char,
vector unsigned char);
vector bool char vec_sel (vector bool char,
vector bool char,
vector bool char);
vector bool char vec_sel (vector bool char,
vector bool char,
vector unsigned char);
vector signed char vec_sl (vector signed char,
vector unsigned char);
vector unsigned char vec_sl (vector unsigned char,
vector unsigned char);
vector signed short vec_sl (vector signed short, vector unsigned short);
vector unsigned short vec_sl (vector unsigned short,
vector unsigned short);
vector signed int vec_sl (vector signed int, vector unsigned int);
vector unsigned int vec_sl (vector unsigned int, vector unsigned int);
vector signed int vec_vslw (vector signed int, vector unsigned int);
vector unsigned int vec_vslw (vector unsigned int, vector unsigned int);
vector signed short vec_vslh (vector signed short,
vector unsigned short);
vector unsigned short vec_vslh (vector unsigned short,
vector unsigned short);
vector signed char vec_vslb (vector signed char, vector unsigned char);
vector unsigned char vec_vslb (vector unsigned char,
vector unsigned char);
vector float vec_sld (vector float, vector float, const int);
vector signed int vec_sld (vector signed int,
vector signed int,
const int);
vector unsigned int vec_sld (vector unsigned int,
vector unsigned int,
const int);
vector bool int vec_sld (vector bool int,
vector bool int,
const int);
vector signed short vec_sld (vector signed short,
vector signed short,
const int);
vector unsigned short vec_sld (vector unsigned short,
vector unsigned short,
const int);
vector bool short vec_sld (vector bool short,
vector bool short,
const int);
vector pixel vec_sld (vector pixel,
vector pixel,
const int);
vector signed char vec_sld (vector signed char,
vector signed char,
const int);
vector unsigned char vec_sld (vector unsigned char,
vector unsigned char,
const int);
vector bool char vec_sld (vector bool char,
vector bool char,
const int);
vector signed int vec_sll (vector signed int,
vector unsigned int);
vector signed int vec_sll (vector signed int,
vector unsigned short);
vector signed int vec_sll (vector signed int,
vector unsigned char);
vector unsigned int vec_sll (vector unsigned int,
vector unsigned int);
vector unsigned int vec_sll (vector unsigned int,
vector unsigned short);
vector unsigned int vec_sll (vector unsigned int,
vector unsigned char);
vector bool int vec_sll (vector bool int,
vector unsigned int);
vector bool int vec_sll (vector bool int,
vector unsigned short);
vector bool int vec_sll (vector bool int,
vector unsigned char);
vector signed short vec_sll (vector signed short,
vector unsigned int);
vector signed short vec_sll (vector signed short,
vector unsigned short);
vector signed short vec_sll (vector signed short,
vector unsigned char);
vector unsigned short vec_sll (vector unsigned short,
vector unsigned int);
vector unsigned short vec_sll (vector unsigned short,
vector unsigned short);
vector unsigned short vec_sll (vector unsigned short,
vector unsigned char);
vector bool short vec_sll (vector bool short, vector unsigned int);
vector bool short vec_sll (vector bool short, vector unsigned short);
vector bool short vec_sll (vector bool short, vector unsigned char);
vector pixel vec_sll (vector pixel, vector unsigned int);
vector pixel vec_sll (vector pixel, vector unsigned short);
vector pixel vec_sll (vector pixel, vector unsigned char);
vector signed char vec_sll (vector signed char, vector unsigned int);
vector signed char vec_sll (vector signed char, vector unsigned short);
vector signed char vec_sll (vector signed char, vector unsigned char);
vector unsigned char vec_sll (vector unsigned char,
vector unsigned int);
vector unsigned char vec_sll (vector unsigned char,
vector unsigned short);
vector unsigned char vec_sll (vector unsigned char,
vector unsigned char);
vector bool char vec_sll (vector bool char, vector unsigned int);
vector bool char vec_sll (vector bool char, vector unsigned short);
vector bool char vec_sll (vector bool char, vector unsigned char);
vector float vec_slo (vector float, vector signed char);
vector float vec_slo (vector float, vector unsigned char);
vector signed int vec_slo (vector signed int, vector signed char);
vector signed int vec_slo (vector signed int, vector unsigned char);
vector unsigned int vec_slo (vector unsigned int, vector signed char);
vector unsigned int vec_slo (vector unsigned int, vector unsigned char);
vector signed short vec_slo (vector signed short, vector signed char);
vector signed short vec_slo (vector signed short, vector unsigned char);
vector unsigned short vec_slo (vector unsigned short,
vector signed char);
vector unsigned short vec_slo (vector unsigned short,
vector unsigned char);
vector pixel vec_slo (vector pixel, vector signed char);
vector pixel vec_slo (vector pixel, vector unsigned char);
vector signed char vec_slo (vector signed char, vector signed char);
vector signed char vec_slo (vector signed char, vector unsigned char);
vector unsigned char vec_slo (vector unsigned char, vector signed char);
vector unsigned char vec_slo (vector unsigned char,
vector unsigned char);
vector signed char vec_splat (vector signed char, const int);
vector unsigned char vec_splat (vector unsigned char, const int);
vector bool char vec_splat (vector bool char, const int);
vector signed short vec_splat (vector signed short, const int);
vector unsigned short vec_splat (vector unsigned short, const int);
vector bool short vec_splat (vector bool short, const int);
vector pixel vec_splat (vector pixel, const int);
vector float vec_splat (vector float, const int);
vector signed int vec_splat (vector signed int, const int);
vector unsigned int vec_splat (vector unsigned int, const int);
vector bool int vec_splat (vector bool int, const int);
vector float vec_vspltw (vector float, const int);
vector signed int vec_vspltw (vector signed int, const int);
vector unsigned int vec_vspltw (vector unsigned int, const int);
vector bool int vec_vspltw (vector bool int, const int);
vector bool short vec_vsplth (vector bool short, const int);
vector signed short vec_vsplth (vector signed short, const int);
vector unsigned short vec_vsplth (vector unsigned short, const int);
vector pixel vec_vsplth (vector pixel, const int);
vector signed char vec_vspltb (vector signed char, const int);
vector unsigned char vec_vspltb (vector unsigned char, const int);
vector bool char vec_vspltb (vector bool char, const int);
vector signed char vec_splat_s8 (const int);
vector signed short vec_splat_s16 (const int);
vector signed int vec_splat_s32 (const int);
vector unsigned char vec_splat_u8 (const int);
vector unsigned short vec_splat_u16 (const int);
vector unsigned int vec_splat_u32 (const int);
vector signed char vec_sr (vector signed char, vector unsigned char);
vector unsigned char vec_sr (vector unsigned char,
vector unsigned char);
vector signed short vec_sr (vector signed short,
vector unsigned short);
vector unsigned short vec_sr (vector unsigned short,
vector unsigned short);
vector signed int vec_sr (vector signed int, vector unsigned int);
vector unsigned int vec_sr (vector unsigned int, vector unsigned int);
vector signed int vec_vsrw (vector signed int, vector unsigned int);
vector unsigned int vec_vsrw (vector unsigned int, vector unsigned int);
vector signed short vec_vsrh (vector signed short,
vector unsigned short);
vector unsigned short vec_vsrh (vector unsigned short,
vector unsigned short);
vector signed char vec_vsrb (vector signed char, vector unsigned char);
vector unsigned char vec_vsrb (vector unsigned char,
vector unsigned char);
vector signed char vec_sra (vector signed char, vector unsigned char);
vector unsigned char vec_sra (vector unsigned char,
vector unsigned char);
vector signed short vec_sra (vector signed short,
vector unsigned short);
vector unsigned short vec_sra (vector unsigned short,
vector unsigned short);
vector signed int vec_sra (vector signed int, vector unsigned int);
vector unsigned int vec_sra (vector unsigned int, vector unsigned int);
vector signed int vec_vsraw (vector signed int, vector unsigned int);
vector unsigned int vec_vsraw (vector unsigned int,
vector unsigned int);
vector signed short vec_vsrah (vector signed short,
vector unsigned short);
vector unsigned short vec_vsrah (vector unsigned short,
vector unsigned short);
vector signed char vec_vsrab (vector signed char, vector unsigned char);
vector unsigned char vec_vsrab (vector unsigned char,
vector unsigned char);
vector signed int vec_srl (vector signed int, vector unsigned int);
vector signed int vec_srl (vector signed int, vector unsigned short);
vector signed int vec_srl (vector signed int, vector unsigned char);
vector unsigned int vec_srl (vector unsigned int, vector unsigned int);
vector unsigned int vec_srl (vector unsigned int,
vector unsigned short);
vector unsigned int vec_srl (vector unsigned int, vector unsigned char);
vector bool int vec_srl (vector bool int, vector unsigned int);
vector bool int vec_srl (vector bool int, vector unsigned short);
vector bool int vec_srl (vector bool int, vector unsigned char);
vector signed short vec_srl (vector signed short, vector unsigned int);
vector signed short vec_srl (vector signed short,
vector unsigned short);
vector signed short vec_srl (vector signed short, vector unsigned char);
vector unsigned short vec_srl (vector unsigned short,
vector unsigned int);
vector unsigned short vec_srl (vector unsigned short,
vector unsigned short);
vector unsigned short vec_srl (vector unsigned short,
vector unsigned char);
vector bool short vec_srl (vector bool short, vector unsigned int);
vector bool short vec_srl (vector bool short, vector unsigned short);
vector bool short vec_srl (vector bool short, vector unsigned char);
vector pixel vec_srl (vector pixel, vector unsigned int);
vector pixel vec_srl (vector pixel, vector unsigned short);
vector pixel vec_srl (vector pixel, vector unsigned char);
vector signed char vec_srl (vector signed char, vector unsigned int);
vector signed char vec_srl (vector signed char, vector unsigned short);
vector signed char vec_srl (vector signed char, vector unsigned char);
vector unsigned char vec_srl (vector unsigned char,
vector unsigned int);
vector unsigned char vec_srl (vector unsigned char,
vector unsigned short);
vector unsigned char vec_srl (vector unsigned char,
vector unsigned char);
vector bool char vec_srl (vector bool char, vector unsigned int);
vector bool char vec_srl (vector bool char, vector unsigned short);
vector bool char vec_srl (vector bool char, vector unsigned char);
vector float vec_sro (vector float, vector signed char);
vector float vec_sro (vector float, vector unsigned char);
vector signed int vec_sro (vector signed int, vector signed char);
vector signed int vec_sro (vector signed int, vector unsigned char);
vector unsigned int vec_sro (vector unsigned int, vector signed char);
vector unsigned int vec_sro (vector unsigned int, vector unsigned char);
vector signed short vec_sro (vector signed short, vector signed char);
vector signed short vec_sro (vector signed short, vector unsigned char);
vector unsigned short vec_sro (vector unsigned short,
vector signed char);
vector unsigned short vec_sro (vector unsigned short,
vector unsigned char);
vector pixel vec_sro (vector pixel, vector signed char);
vector pixel vec_sro (vector pixel, vector unsigned char);
vector signed char vec_sro (vector signed char, vector signed char);
vector signed char vec_sro (vector signed char, vector unsigned char);
vector unsigned char vec_sro (vector unsigned char, vector signed char);
vector unsigned char vec_sro (vector unsigned char,
vector unsigned char);
void vec_st (vector float, int, vector float *);
void vec_st (vector float, int, float *);
void vec_st (vector signed int, int, vector signed int *);
void vec_st (vector signed int, int, int *);
void vec_st (vector unsigned int, int, vector unsigned int *);
void vec_st (vector unsigned int, int, unsigned int *);
void vec_st (vector bool int, int, vector bool int *);
void vec_st (vector bool int, int, unsigned int *);
void vec_st (vector bool int, int, int *);
void vec_st (vector signed short, int, vector signed short *);
void vec_st (vector signed short, int, short *);
void vec_st (vector unsigned short, int, vector unsigned short *);
void vec_st (vector unsigned short, int, unsigned short *);
void vec_st (vector bool short, int, vector bool short *);
void vec_st (vector bool short, int, unsigned short *);
void vec_st (vector pixel, int, vector pixel *);
void vec_st (vector pixel, int, unsigned short *);
void vec_st (vector pixel, int, short *);
void vec_st (vector bool short, int, short *);
void vec_st (vector signed char, int, vector signed char *);
void vec_st (vector signed char, int, signed char *);
void vec_st (vector unsigned char, int, vector unsigned char *);
void vec_st (vector unsigned char, int, unsigned char *);
void vec_st (vector bool char, int, vector bool char *);
void vec_st (vector bool char, int, unsigned char *);
void vec_st (vector bool char, int, signed char *);
void vec_ste (vector signed char, int, signed char *);
void vec_ste (vector unsigned char, int, unsigned char *);
void vec_ste (vector bool char, int, signed char *);
void vec_ste (vector bool char, int, unsigned char *);
void vec_ste (vector signed short, int, short *);
void vec_ste (vector unsigned short, int, unsigned short *);
void vec_ste (vector bool short, int, short *);
void vec_ste (vector bool short, int, unsigned short *);
void vec_ste (vector pixel, int, short *);
void vec_ste (vector pixel, int, unsigned short *);
void vec_ste (vector float, int, float *);
void vec_ste (vector signed int, int, int *);
void vec_ste (vector unsigned int, int, unsigned int *);
void vec_ste (vector bool int, int, int *);
void vec_ste (vector bool int, int, unsigned int *);
void vec_stvewx (vector float, int, float *);
void vec_stvewx (vector signed int, int, int *);
void vec_stvewx (vector unsigned int, int, unsigned int *);
void vec_stvewx (vector bool int, int, int *);
void vec_stvewx (vector bool int, int, unsigned int *);
void vec_stvehx (vector signed short, int, short *);
void vec_stvehx (vector unsigned short, int, unsigned short *);
void vec_stvehx (vector bool short, int, short *);
void vec_stvehx (vector bool short, int, unsigned short *);
void vec_stvehx (vector pixel, int, short *);
void vec_stvehx (vector pixel, int, unsigned short *);
void vec_stvebx (vector signed char, int, signed char *);
void vec_stvebx (vector unsigned char, int, unsigned char *);
void vec_stvebx (vector bool char, int, signed char *);
void vec_stvebx (vector bool char, int, unsigned char *);
void vec_stl (vector float, int, vector float *);
void vec_stl (vector float, int, float *);
void vec_stl (vector signed int, int, vector signed int *);
void vec_stl (vector signed int, int, int *);
void vec_stl (vector unsigned int, int, vector unsigned int *);
void vec_stl (vector unsigned int, int, unsigned int *);
void vec_stl (vector bool int, int, vector bool int *);
void vec_stl (vector bool int, int, unsigned int *);
void vec_stl (vector bool int, int, int *);
void vec_stl (vector signed short, int, vector signed short *);
void vec_stl (vector signed short, int, short *);
void vec_stl (vector unsigned short, int, vector unsigned short *);
void vec_stl (vector unsigned short, int, unsigned short *);
void vec_stl (vector bool short, int, vector bool short *);
void vec_stl (vector bool short, int, unsigned short *);
void vec_stl (vector bool short, int, short *);
void vec_stl (vector pixel, int, vector pixel *);
void vec_stl (vector pixel, int, unsigned short *);
void vec_stl (vector pixel, int, short *);
void vec_stl (vector signed char, int, vector signed char *);
void vec_stl (vector signed char, int, signed char *);
void vec_stl (vector unsigned char, int, vector unsigned char *);
void vec_stl (vector unsigned char, int, unsigned char *);
void vec_stl (vector bool char, int, vector bool char *);
void vec_stl (vector bool char, int, unsigned char *);
void vec_stl (vector bool char, int, signed char *);
vector signed char vec_sub (vector bool char, vector signed char);
vector signed char vec_sub (vector signed char, vector bool char);
vector signed char vec_sub (vector signed char, vector signed char);
vector unsigned char vec_sub (vector bool char, vector unsigned char);
vector unsigned char vec_sub (vector unsigned char, vector bool char);
vector unsigned char vec_sub (vector unsigned char,
vector unsigned char);
vector signed short vec_sub (vector bool short, vector signed short);
vector signed short vec_sub (vector signed short, vector bool short);
vector signed short vec_sub (vector signed short, vector signed short);
vector unsigned short vec_sub (vector bool short,
vector unsigned short);
vector unsigned short vec_sub (vector unsigned short,
vector bool short);
vector unsigned short vec_sub (vector unsigned short,
vector unsigned short);
vector signed int vec_sub (vector bool int, vector signed int);
vector signed int vec_sub (vector signed int, vector bool int);
vector signed int vec_sub (vector signed int, vector signed int);
vector unsigned int vec_sub (vector bool int, vector unsigned int);
vector unsigned int vec_sub (vector unsigned int, vector bool int);
vector unsigned int vec_sub (vector unsigned int, vector unsigned int);
vector float vec_sub (vector float, vector float);
vector float vec_vsubfp (vector float, vector float);
vector signed int vec_vsubuwm (vector bool int, vector signed int);
vector signed int vec_vsubuwm (vector signed int, vector bool int);
vector signed int vec_vsubuwm (vector signed int, vector signed int);
vector unsigned int vec_vsubuwm (vector bool int, vector unsigned int);
vector unsigned int vec_vsubuwm (vector unsigned int, vector bool int);
vector unsigned int vec_vsubuwm (vector unsigned int,
vector unsigned int);
vector signed short vec_vsubuhm (vector bool short,
vector signed short);
vector signed short vec_vsubuhm (vector signed short,
vector bool short);
vector signed short vec_vsubuhm (vector signed short,
vector signed short);
vector unsigned short vec_vsubuhm (vector bool short,
vector unsigned short);
vector unsigned short vec_vsubuhm (vector unsigned short,
vector bool short);
vector unsigned short vec_vsubuhm (vector unsigned short,
vector unsigned short);
vector signed char vec_vsububm (vector bool char, vector signed char);
vector signed char vec_vsububm (vector signed char, vector bool char);
vector signed char vec_vsububm (vector signed char, vector signed char);
vector unsigned char vec_vsububm (vector bool char,
vector unsigned char);
vector unsigned char vec_vsububm (vector unsigned char,
vector bool char);
vector unsigned char vec_vsububm (vector unsigned char,
vector unsigned char);
vector unsigned int vec_subc (vector unsigned int, vector unsigned int);
vector unsigned char vec_subs (vector bool char, vector unsigned char);
vector unsigned char vec_subs (vector unsigned char, vector bool char);
vector unsigned char vec_subs (vector unsigned char,
vector unsigned char);
vector signed char vec_subs (vector bool char, vector signed char);
vector signed char vec_subs (vector signed char, vector bool char);
vector signed char vec_subs (vector signed char, vector signed char);
vector unsigned short vec_subs (vector bool short,
vector unsigned short);
vector unsigned short vec_subs (vector unsigned short,
vector bool short);
vector unsigned short vec_subs (vector unsigned short,
vector unsigned short);
vector signed short vec_subs (vector bool short, vector signed short);
vector signed short vec_subs (vector signed short, vector bool short);
vector signed short vec_subs (vector signed short, vector signed short);
vector unsigned int vec_subs (vector bool int, vector unsigned int);
vector unsigned int vec_subs (vector unsigned int, vector bool int);
vector unsigned int vec_subs (vector unsigned int, vector unsigned int);
vector signed int vec_subs (vector bool int, vector signed int);
vector signed int vec_subs (vector signed int, vector bool int);
vector signed int vec_subs (vector signed int, vector signed int);
vector signed int vec_vsubsws (vector bool int, vector signed int);
vector signed int vec_vsubsws (vector signed int, vector bool int);
vector signed int vec_vsubsws (vector signed int, vector signed int);
vector unsigned int vec_vsubuws (vector bool int, vector unsigned int);
vector unsigned int vec_vsubuws (vector unsigned int, vector bool int);
vector unsigned int vec_vsubuws (vector unsigned int,
vector unsigned int);
vector signed short vec_vsubshs (vector bool short,
vector signed short);
vector signed short vec_vsubshs (vector signed short,
vector bool short);
vector signed short vec_vsubshs (vector signed short,
vector signed short);
vector unsigned short vec_vsubuhs (vector bool short,
vector unsigned short);
vector unsigned short vec_vsubuhs (vector unsigned short,
vector bool short);
vector unsigned short vec_vsubuhs (vector unsigned short,
vector unsigned short);
vector signed char vec_vsubsbs (vector bool char, vector signed char);
vector signed char vec_vsubsbs (vector signed char, vector bool char);
vector signed char vec_vsubsbs (vector signed char, vector signed char);
vector unsigned char vec_vsububs (vector bool char,
vector unsigned char);
vector unsigned char vec_vsububs (vector unsigned char,
vector bool char);
vector unsigned char vec_vsububs (vector unsigned char,
vector unsigned char);
vector unsigned int vec_sum4s (vector unsigned char,
vector unsigned int);
vector signed int vec_sum4s (vector signed char, vector signed int);
vector signed int vec_sum4s (vector signed short, vector signed int);
vector signed int vec_vsum4shs (vector signed short, vector signed int);
vector signed int vec_vsum4sbs (vector signed char, vector signed int);
vector unsigned int vec_vsum4ubs (vector unsigned char,
vector unsigned int);
vector signed int vec_sum2s (vector signed int, vector signed int);
vector signed int vec_sums (vector signed int, vector signed int);
vector float vec_trunc (vector float);
vector signed short vec_unpackh (vector signed char);
vector bool short vec_unpackh (vector bool char);
vector signed int vec_unpackh (vector signed short);
vector bool int vec_unpackh (vector bool short);
vector unsigned int vec_unpackh (vector pixel);
vector bool int vec_vupkhsh (vector bool short);
vector signed int vec_vupkhsh (vector signed short);
vector unsigned int vec_vupkhpx (vector pixel);
vector bool short vec_vupkhsb (vector bool char);
vector signed short vec_vupkhsb (vector signed char);
vector signed short vec_unpackl (vector signed char);
vector bool short vec_unpackl (vector bool char);
vector unsigned int vec_unpackl (vector pixel);
vector signed int vec_unpackl (vector signed short);
vector bool int vec_unpackl (vector bool short);
vector unsigned int vec_vupklpx (vector pixel);
vector bool int vec_vupklsh (vector bool short);
vector signed int vec_vupklsh (vector signed short);
vector bool short vec_vupklsb (vector bool char);
vector signed short vec_vupklsb (vector signed char);
vector float vec_xor (vector float, vector float);
vector float vec_xor (vector float, vector bool int);
vector float vec_xor (vector bool int, vector float);
vector bool int vec_xor (vector bool int, vector bool int);
vector signed int vec_xor (vector bool int, vector signed int);
vector signed int vec_xor (vector signed int, vector bool int);
vector signed int vec_xor (vector signed int, vector signed int);
vector unsigned int vec_xor (vector bool int, vector unsigned int);
vector unsigned int vec_xor (vector unsigned int, vector bool int);
vector unsigned int vec_xor (vector unsigned int, vector unsigned int);
vector bool short vec_xor (vector bool short, vector bool short);
vector signed short vec_xor (vector bool short, vector signed short);
vector signed short vec_xor (vector signed short, vector bool short);
vector signed short vec_xor (vector signed short, vector signed short);
vector unsigned short vec_xor (vector bool short,
vector unsigned short);
vector unsigned short vec_xor (vector unsigned short,
vector bool short);
vector unsigned short vec_xor (vector unsigned short,
vector unsigned short);
vector signed char vec_xor (vector bool char, vector signed char);
vector bool char vec_xor (vector bool char, vector bool char);
vector signed char vec_xor (vector signed char, vector bool char);
vector signed char vec_xor (vector signed char, vector signed char);
vector unsigned char vec_xor (vector bool char, vector unsigned char);
vector unsigned char vec_xor (vector unsigned char, vector bool char);
vector unsigned char vec_xor (vector unsigned char,
vector unsigned char);
int vec_all_eq (vector signed char, vector bool char);
int vec_all_eq (vector signed char, vector signed char);
int vec_all_eq (vector unsigned char, vector bool char);
int vec_all_eq (vector unsigned char, vector unsigned char);
int vec_all_eq (vector bool char, vector bool char);
int vec_all_eq (vector bool char, vector unsigned char);
int vec_all_eq (vector bool char, vector signed char);
int vec_all_eq (vector signed short, vector bool short);
int vec_all_eq (vector signed short, vector signed short);
int vec_all_eq (vector unsigned short, vector bool short);
int vec_all_eq (vector unsigned short, vector unsigned short);
int vec_all_eq (vector bool short, vector bool short);
int vec_all_eq (vector bool short, vector unsigned short);
int vec_all_eq (vector bool short, vector signed short);
int vec_all_eq (vector pixel, vector pixel);
int vec_all_eq (vector signed int, vector bool int);
int vec_all_eq (vector signed int, vector signed int);
int vec_all_eq (vector unsigned int, vector bool int);
int vec_all_eq (vector unsigned int, vector unsigned int);
int vec_all_eq (vector bool int, vector bool int);
int vec_all_eq (vector bool int, vector unsigned int);
int vec_all_eq (vector bool int, vector signed int);
int vec_all_eq (vector float, vector float);
int vec_all_ge (vector bool char, vector unsigned char);
int vec_all_ge (vector unsigned char, vector bool char);
int vec_all_ge (vector unsigned char, vector unsigned char);
int vec_all_ge (vector bool char, vector signed char);
int vec_all_ge (vector signed char, vector bool char);
int vec_all_ge (vector signed char, vector signed char);
int vec_all_ge (vector bool short, vector unsigned short);
int vec_all_ge (vector unsigned short, vector bool short);
int vec_all_ge (vector unsigned short, vector unsigned short);
int vec_all_ge (vector signed short, vector signed short);
int vec_all_ge (vector bool short, vector signed short);
int vec_all_ge (vector signed short, vector bool short);
int vec_all_ge (vector bool int, vector unsigned int);
int vec_all_ge (vector unsigned int, vector bool int);
int vec_all_ge (vector unsigned int, vector unsigned int);
int vec_all_ge (vector bool int, vector signed int);
int vec_all_ge (vector signed int, vector bool int);
int vec_all_ge (vector signed int, vector signed int);
int vec_all_ge (vector float, vector float);
int vec_all_gt (vector bool char, vector unsigned char);
int vec_all_gt (vector unsigned char, vector bool char);
int vec_all_gt (vector unsigned char, vector unsigned char);
int vec_all_gt (vector bool char, vector signed char);
int vec_all_gt (vector signed char, vector bool char);
int vec_all_gt (vector signed char, vector signed char);
int vec_all_gt (vector bool short, vector unsigned short);
int vec_all_gt (vector unsigned short, vector bool short);
int vec_all_gt (vector unsigned short, vector unsigned short);
int vec_all_gt (vector bool short, vector signed short);
int vec_all_gt (vector signed short, vector bool short);
int vec_all_gt (vector signed short, vector signed short);
int vec_all_gt (vector bool int, vector unsigned int);
int vec_all_gt (vector unsigned int, vector bool int);
int vec_all_gt (vector unsigned int, vector unsigned int);
int vec_all_gt (vector bool int, vector signed int);
int vec_all_gt (vector signed int, vector bool int);
int vec_all_gt (vector signed int, vector signed int);
int vec_all_gt (vector float, vector float);
int vec_all_in (vector float, vector float);
int vec_all_le (vector bool char, vector unsigned char);
int vec_all_le (vector unsigned char, vector bool char);
int vec_all_le (vector unsigned char, vector unsigned char);
int vec_all_le (vector bool char, vector signed char);
int vec_all_le (vector signed char, vector bool char);
int vec_all_le (vector signed char, vector signed char);
int vec_all_le (vector bool short, vector unsigned short);
int vec_all_le (vector unsigned short, vector bool short);
int vec_all_le (vector unsigned short, vector unsigned short);
int vec_all_le (vector bool short, vector signed short);
int vec_all_le (vector signed short, vector bool short);
int vec_all_le (vector signed short, vector signed short);
int vec_all_le (vector bool int, vector unsigned int);
int vec_all_le (vector unsigned int, vector bool int);
int vec_all_le (vector unsigned int, vector unsigned int);
int vec_all_le (vector bool int, vector signed int);
int vec_all_le (vector signed int, vector bool int);
int vec_all_le (vector signed int, vector signed int);
int vec_all_le (vector float, vector float);
int vec_all_lt (vector bool char, vector unsigned char);
int vec_all_lt (vector unsigned char, vector bool char);
int vec_all_lt (vector unsigned char, vector unsigned char);
int vec_all_lt (vector bool char, vector signed char);
int vec_all_lt (vector signed char, vector bool char);
int vec_all_lt (vector signed char, vector signed char);
int vec_all_lt (vector bool short, vector unsigned short);
int vec_all_lt (vector unsigned short, vector bool short);
int vec_all_lt (vector unsigned short, vector unsigned short);
int vec_all_lt (vector bool short, vector signed short);
int vec_all_lt (vector signed short, vector bool short);
int vec_all_lt (vector signed short, vector signed short);
int vec_all_lt (vector bool int, vector unsigned int);
int vec_all_lt (vector unsigned int, vector bool int);
int vec_all_lt (vector unsigned int, vector unsigned int);
int vec_all_lt (vector bool int, vector signed int);
int vec_all_lt (vector signed int, vector bool int);
int vec_all_lt (vector signed int, vector signed int);
int vec_all_lt (vector float, vector float);
int vec_all_nan (vector float);
int vec_all_ne (vector signed char, vector bool char);
int vec_all_ne (vector signed char, vector signed char);
int vec_all_ne (vector unsigned char, vector bool char);
int vec_all_ne (vector unsigned char, vector unsigned char);
int vec_all_ne (vector bool char, vector bool char);
int vec_all_ne (vector bool char, vector unsigned char);
int vec_all_ne (vector bool char, vector signed char);
int vec_all_ne (vector signed short, vector bool short);
int vec_all_ne (vector signed short, vector signed short);
int vec_all_ne (vector unsigned short, vector bool short);
int vec_all_ne (vector unsigned short, vector unsigned short);
int vec_all_ne (vector bool short, vector bool short);
int vec_all_ne (vector bool short, vector unsigned short);
int vec_all_ne (vector bool short, vector signed short);
int vec_all_ne (vector pixel, vector pixel);
int vec_all_ne (vector signed int, vector bool int);
int vec_all_ne (vector signed int, vector signed int);
int vec_all_ne (vector unsigned int, vector bool int);
int vec_all_ne (vector unsigned int, vector unsigned int);
int vec_all_ne (vector bool int, vector bool int);
int vec_all_ne (vector bool int, vector unsigned int);
int vec_all_ne (vector bool int, vector signed int);
int vec_all_ne (vector float, vector float);
int vec_all_nge (vector float, vector float);
int vec_all_ngt (vector float, vector float);
int vec_all_nle (vector float, vector float);
int vec_all_nlt (vector float, vector float);
int vec_all_numeric (vector float);
int vec_any_eq (vector signed char, vector bool char);
int vec_any_eq (vector signed char, vector signed char);
int vec_any_eq (vector unsigned char, vector bool char);
int vec_any_eq (vector unsigned char, vector unsigned char);
int vec_any_eq (vector bool char, vector bool char);
int vec_any_eq (vector bool char, vector unsigned char);
int vec_any_eq (vector bool char, vector signed char);
int vec_any_eq (vector signed short, vector bool short);
int vec_any_eq (vector signed short, vector signed short);
int vec_any_eq (vector unsigned short, vector bool short);
int vec_any_eq (vector unsigned short, vector unsigned short);
int vec_any_eq (vector bool short, vector bool short);
int vec_any_eq (vector bool short, vector unsigned short);
int vec_any_eq (vector bool short, vector signed short);
int vec_any_eq (vector pixel, vector pixel);
int vec_any_eq (vector signed int, vector bool int);
int vec_any_eq (vector signed int, vector signed int);
int vec_any_eq (vector unsigned int, vector bool int);
int vec_any_eq (vector unsigned int, vector unsigned int);
int vec_any_eq (vector bool int, vector bool int);
int vec_any_eq (vector bool int, vector unsigned int);
int vec_any_eq (vector bool int, vector signed int);
int vec_any_eq (vector float, vector float);
int vec_any_ge (vector signed char, vector bool char);
int vec_any_ge (vector unsigned char, vector bool char);
int vec_any_ge (vector unsigned char, vector unsigned char);
int vec_any_ge (vector signed char, vector signed char);
int vec_any_ge (vector bool char, vector unsigned char);
int vec_any_ge (vector bool char, vector signed char);
int vec_any_ge (vector unsigned short, vector bool short);
int vec_any_ge (vector unsigned short, vector unsigned short);
int vec_any_ge (vector signed short, vector signed short);
int vec_any_ge (vector signed short, vector bool short);
int vec_any_ge (vector bool short, vector unsigned short);
int vec_any_ge (vector bool short, vector signed short);
int vec_any_ge (vector signed int, vector bool int);
int vec_any_ge (vector unsigned int, vector bool int);
int vec_any_ge (vector unsigned int, vector unsigned int);
int vec_any_ge (vector signed int, vector signed int);
int vec_any_ge (vector bool int, vector unsigned int);
int vec_any_ge (vector bool int, vector signed int);
int vec_any_ge (vector float, vector float);
int vec_any_gt (vector bool char, vector unsigned char);
int vec_any_gt (vector unsigned char, vector bool char);
int vec_any_gt (vector unsigned char, vector unsigned char);
int vec_any_gt (vector bool char, vector signed char);
int vec_any_gt (vector signed char, vector bool char);
int vec_any_gt (vector signed char, vector signed char);
int vec_any_gt (vector bool short, vector unsigned short);
int vec_any_gt (vector unsigned short, vector bool short);
int vec_any_gt (vector unsigned short, vector unsigned short);
int vec_any_gt (vector bool short, vector signed short);
int vec_any_gt (vector signed short, vector bool short);
int vec_any_gt (vector signed short, vector signed short);
int vec_any_gt (vector bool int, vector unsigned int);
int vec_any_gt (vector unsigned int, vector bool int);
int vec_any_gt (vector unsigned int, vector unsigned int);
int vec_any_gt (vector bool int, vector signed int);
int vec_any_gt (vector signed int, vector bool int);
int vec_any_gt (vector signed int, vector signed int);
int vec_any_gt (vector float, vector float);
int vec_any_le (vector bool char, vector unsigned char);
int vec_any_le (vector unsigned char, vector bool char);
int vec_any_le (vector unsigned char, vector unsigned char);
int vec_any_le (vector bool char, vector signed char);
int vec_any_le (vector signed char, vector bool char);
int vec_any_le (vector signed char, vector signed char);
int vec_any_le (vector bool short, vector unsigned short);
int vec_any_le (vector unsigned short, vector bool short);
int vec_any_le (vector unsigned short, vector unsigned short);
int vec_any_le (vector bool short, vector signed short);
int vec_any_le (vector signed short, vector bool short);
int vec_any_le (vector signed short, vector signed short);
int vec_any_le (vector bool int, vector unsigned int);
int vec_any_le (vector unsigned int, vector bool int);
int vec_any_le (vector unsigned int, vector unsigned int);
int vec_any_le (vector bool int, vector signed int);
int vec_any_le (vector signed int, vector bool int);
int vec_any_le (vector signed int, vector signed int);
int vec_any_le (vector float, vector float);
int vec_any_lt (vector bool char, vector unsigned char);
int vec_any_lt (vector unsigned char, vector bool char);
int vec_any_lt (vector unsigned char, vector unsigned char);
int vec_any_lt (vector bool char, vector signed char);
int vec_any_lt (vector signed char, vector bool char);
int vec_any_lt (vector signed char, vector signed char);
int vec_any_lt (vector bool short, vector unsigned short);
int vec_any_lt (vector unsigned short, vector bool short);
int vec_any_lt (vector unsigned short, vector unsigned short);
int vec_any_lt (vector bool short, vector signed short);
int vec_any_lt (vector signed short, vector bool short);
int vec_any_lt (vector signed short, vector signed short);
int vec_any_lt (vector bool int, vector unsigned int);
int vec_any_lt (vector unsigned int, vector bool int);
int vec_any_lt (vector unsigned int, vector unsigned int);
int vec_any_lt (vector bool int, vector signed int);
int vec_any_lt (vector signed int, vector bool int);
int vec_any_lt (vector signed int, vector signed int);
int vec_any_lt (vector float, vector float);
int vec_any_nan (vector float);
int vec_any_ne (vector signed char, vector bool char);
int vec_any_ne (vector signed char, vector signed char);
int vec_any_ne (vector unsigned char, vector bool char);
int vec_any_ne (vector unsigned char, vector unsigned char);
int vec_any_ne (vector bool char, vector bool char);
int vec_any_ne (vector bool char, vector unsigned char);
int vec_any_ne (vector bool char, vector signed char);
int vec_any_ne (vector signed short, vector bool short);
int vec_any_ne (vector signed short, vector signed short);
int vec_any_ne (vector unsigned short, vector bool short);
int vec_any_ne (vector unsigned short, vector unsigned short);
int vec_any_ne (vector bool short, vector bool short);
int vec_any_ne (vector bool short, vector unsigned short);
int vec_any_ne (vector bool short, vector signed short);
int vec_any_ne (vector pixel, vector pixel);
int vec_any_ne (vector signed int, vector bool int);
int vec_any_ne (vector signed int, vector signed int);
int vec_any_ne (vector unsigned int, vector bool int);
int vec_any_ne (vector unsigned int, vector unsigned int);
int vec_any_ne (vector bool int, vector bool int);
int vec_any_ne (vector bool int, vector unsigned int);
int vec_any_ne (vector bool int, vector signed int);
int vec_any_ne (vector float, vector float);
int vec_any_nge (vector float, vector float);
int vec_any_ngt (vector float, vector float);
int vec_any_nle (vector float, vector float);
int vec_any_nlt (vector float, vector float);
int vec_any_numeric (vector float);
int vec_any_out (vector float, vector float);
If the vector/scalar (VSX) instruction set is available, the following additional functions are available:
vector double vec_abs (vector double);
vector double vec_add (vector double, vector double);
vector double vec_and (vector double, vector double);
vector double vec_and (vector double, vector bool long);
vector double vec_and (vector bool long, vector double);
vector double vec_andc (vector double, vector double);
vector double vec_andc (vector double, vector bool long);
vector double vec_andc (vector bool long, vector double);
vector double vec_ceil (vector double);
vector bool long vec_cmpeq (vector double, vector double);
vector bool long vec_cmpge (vector double, vector double);
vector bool long vec_cmpgt (vector double, vector double);
vector bool long vec_cmple (vector double, vector double);
vector bool long vec_cmplt (vector double, vector double);
vector float vec_div (vector float, vector float);
vector double vec_div (vector double, vector double);
vector double vec_floor (vector double);
vector double vec_ld (int, const vector double *);
vector double vec_ld (int, const double *);
vector double vec_ldl (int, const vector double *);
vector double vec_ldl (int, const double *);
vector unsigned char vec_lvsl (int, const volatile double *);
vector unsigned char vec_lvsr (int, const volatile double *);
vector double vec_madd (vector double, vector double, vector double);
vector double vec_max (vector double, vector double);
vector double vec_min (vector double, vector double);
vector float vec_msub (vector float, vector float, vector float);
vector double vec_msub (vector double, vector double, vector double);
vector float vec_mul (vector float, vector float);
vector double vec_mul (vector double, vector double);
vector float vec_nearbyint (vector float);
vector double vec_nearbyint (vector double);
vector float vec_nmadd (vector float, vector float, vector float);
vector double vec_nmadd (vector double, vector double, vector double);
vector double vec_nmsub (vector double, vector double, vector double);
vector double vec_nor (vector double, vector double);
vector double vec_or (vector double, vector double);
vector double vec_or (vector double, vector bool long);
vector double vec_or (vector bool long, vector double);
vector double vec_perm (vector double,
vector double,
vector unsigned char);
vector double vec_rint (vector double);
vector double vec_recip (vector double, vector double);
vector double vec_rsqrt (vector double);
vector double vec_rsqrte (vector double);
vector double vec_sel (vector double, vector double, vector bool long);
vector double vec_sel (vector double, vector double, vector unsigned long);
vector double vec_sub (vector double, vector double);
vector float vec_sqrt (vector float);
vector double vec_sqrt (vector double);
void vec_st (vector double, int, vector double *);
void vec_st (vector double, int, double *);
vector double vec_trunc (vector double);
vector double vec_xor (vector double, vector double);
vector double vec_xor (vector double, vector bool long);
vector double vec_xor (vector bool long, vector double);
int vec_all_eq (vector double, vector double);
int vec_all_ge (vector double, vector double);
int vec_all_gt (vector double, vector double);
int vec_all_le (vector double, vector double);
int vec_all_lt (vector double, vector double);
int vec_all_nan (vector double);
int vec_all_ne (vector double, vector double);
int vec_all_nge (vector double, vector double);
int vec_all_ngt (vector double, vector double);
int vec_all_nle (vector double, vector double);
int vec_all_nlt (vector double, vector double);
int vec_all_numeric (vector double);
int vec_any_eq (vector double, vector double);
int vec_any_ge (vector double, vector double);
int vec_any_gt (vector double, vector double);
int vec_any_le (vector double, vector double);
int vec_any_lt (vector double, vector double);
int vec_any_nan (vector double);
int vec_any_ne (vector double, vector double);
int vec_any_nge (vector double, vector double);
int vec_any_ngt (vector double, vector double);
int vec_any_nle (vector double, vector double);
int vec_any_nlt (vector double, vector double);
int vec_any_numeric (vector double);
vector double vec_vsx_ld (int, const vector double *);
vector double vec_vsx_ld (int, const double *);
vector float vec_vsx_ld (int, const vector float *);
vector float vec_vsx_ld (int, const float *);
vector bool int vec_vsx_ld (int, const vector bool int *);
vector signed int vec_vsx_ld (int, const vector signed int *);
vector signed int vec_vsx_ld (int, const int *);
vector signed int vec_vsx_ld (int, const long *);
vector unsigned int vec_vsx_ld (int, const vector unsigned int *);
vector unsigned int vec_vsx_ld (int, const unsigned int *);
vector unsigned int vec_vsx_ld (int, const unsigned long *);
vector bool short vec_vsx_ld (int, const vector bool short *);
vector pixel vec_vsx_ld (int, const vector pixel *);
vector signed short vec_vsx_ld (int, const vector signed short *);
vector signed short vec_vsx_ld (int, const short *);
vector unsigned short vec_vsx_ld (int, const vector unsigned short *);
vector unsigned short vec_vsx_ld (int, const unsigned short *);
vector bool char vec_vsx_ld (int, const vector bool char *);
vector signed char vec_vsx_ld (int, const vector signed char *);
vector signed char vec_vsx_ld (int, const signed char *);
vector unsigned char vec_vsx_ld (int, const vector unsigned char *);
vector unsigned char vec_vsx_ld (int, const unsigned char *);
void vec_vsx_st (vector double, int, vector double *);
void vec_vsx_st (vector double, int, double *);
void vec_vsx_st (vector float, int, vector float *);
void vec_vsx_st (vector float, int, float *);
void vec_vsx_st (vector signed int, int, vector signed int *);
void vec_vsx_st (vector signed int, int, int *);
void vec_vsx_st (vector unsigned int, int, vector unsigned int *);
void vec_vsx_st (vector unsigned int, int, unsigned int *);
void vec_vsx_st (vector bool int, int, vector bool int *);
void vec_vsx_st (vector bool int, int, unsigned int *);
void vec_vsx_st (vector bool int, int, int *);
void vec_vsx_st (vector signed short, int, vector signed short *);
void vec_vsx_st (vector signed short, int, short *);
void vec_vsx_st (vector unsigned short, int, vector unsigned short *);
void vec_vsx_st (vector unsigned short, int, unsigned short *);
void vec_vsx_st (vector bool short, int, vector bool short *);
void vec_vsx_st (vector bool short, int, unsigned short *);
void vec_vsx_st (vector pixel, int, vector pixel *);
void vec_vsx_st (vector pixel, int, unsigned short *);
void vec_vsx_st (vector pixel, int, short *);
void vec_vsx_st (vector bool short, int, short *);
void vec_vsx_st (vector signed char, int, vector signed char *);
void vec_vsx_st (vector signed char, int, signed char *);
void vec_vsx_st (vector unsigned char, int, vector unsigned char *);
void vec_vsx_st (vector unsigned char, int, unsigned char *);
void vec_vsx_st (vector bool char, int, vector bool char *);
void vec_vsx_st (vector bool char, int, unsigned char *);
void vec_vsx_st (vector bool char, int, signed char *);
Note that the ‘vec_ld’ and ‘vec_st’ builtins will always generate the Altivec ‘LVX’ and ‘STVX’ instructions even if the VSX instruction set is available. The ‘vec_vsx_ld’ and ‘vec_vsx_st’ builtins will always generate the VSX ‘LXVD2X’, ‘LXVW4X’, ‘STXVD2X’, and ‘STXVW4X’ instructions.
GCC provides a few other builtins on Powerpc to access certain instructions:
float __builtin_recipdivf (float, float);
float __builtin_rsqrtf (float);
double __builtin_recipdiv (double, double);
double __builtin_rsqrt (double);
long __builtin_bpermd (long, long);
int __builtin_bswap16 (int);
The vec_rsqrt, __builtin_rsqrt, and
__builtin_rsqrtf functions generate multiple instructions to
implement the reciprocal sqrt functionality using reciprocal sqrt
estimate instructions.
The __builtin_recipdiv, and __builtin_recipdivf
functions generate multiple instructions to implement division using
the reciprocal estimate instructions.
GCC supports some of the RX instructions which cannot be expressed in the C programming language via the use of built-in functions. The following functions are supported:
Generates the
clrpswmachine instruction to clear the specified bit in the processor status word.
Generates the
intmachine instruction to generate an interrupt with the specified value.
Generates the
machimachine instruction to add the result of multiplying the top 16-bits of the two arguments into the accumulator.
Generates the
maclomachine instruction to add the result of multiplying the bottom 16-bits of the two arguments into the accumulator.
Generates the
mulhimachine instruction to place the result of multiplying the top 16-bits of the two arguments into the accumulator.
Generates the
mullomachine instruction to place the result of multiplying the bottom 16-bits of the two arguments into the accumulator.
Generates the
mvfachimachine instruction to read the top 32-bits of the accumulator.
Generates the
mvfacmimachine instruction to read the middle 32-bits of the accumulator.
Generates the
mvfcmachine instruction which reads the control register specified in its argument and returns its value.
Generates the
mvtachimachine instruction to set the top 32-bits of the accumulator.
Generates the
mvtaclomachine instruction to set the bottom 32-bits of the accumulator.
Generates the
mvtcmachine instruction which sets control register numberregtoval.
Generates the
mvtiplmachine instruction set the interrupt priority level.
Generates the
racwmachine instruction to round the accumulator according to the specified mode.
Generates the
revwmachine instruction which swaps the bytes in the argument so that bits 0–7 now occupy bits 8–15 and vice versa, and also bits 16–23 occupy bits 24–31 and vice versa.
Generates the
rmpamachine instruction which initiates a repeated multiply and accumulate sequence.
Generates the
roundmachine instruction which returns the floating point argument rounded according to the current rounding mode set in the floating point status word register.
Generates the
satmachine instruction which returns the saturated value of the argument.
Generates the
setpswmachine instruction to set the specified bit in the processor status word.
GCC supports SIMD operations on the SPARC using both the generic vector extensions (see Vector Extensions) as well as built-in functions for the SPARC Visual Instruction Set (VIS). When you use the -mvis switch, the VIS extension is exposed as the following built-in functions:
typedef int v1si __attribute__ ((vector_size (4)));
typedef int v2si __attribute__ ((vector_size (8)));
typedef short v4hi __attribute__ ((vector_size (8)));
typedef short v2hi __attribute__ ((vector_size (4)));
typedef unsigned char v8qi __attribute__ ((vector_size (8)));
typedef unsigned char v4qi __attribute__ ((vector_size (4)));
void __builtin_vis_write_gsr (int64_t);
int64_t __builtin_vis_read_gsr (void);
void * __builtin_vis_alignaddr (void *, long);
void * __builtin_vis_alignaddrl (void *, long);
int64_t __builtin_vis_faligndatadi (int64_t, int64_t);
v2si __builtin_vis_faligndatav2si (v2si, v2si);
v4hi __builtin_vis_faligndatav4hi (v4si, v4si);
v8qi __builtin_vis_faligndatav8qi (v8qi, v8qi);
v4hi __builtin_vis_fexpand (v4qi);
v4hi __builtin_vis_fmul8x16 (v4qi, v4hi);
v4hi __builtin_vis_fmul8x16au (v4qi, v2hi);
v4hi __builtin_vis_fmul8x16al (v4qi, v2hi);
v4hi __builtin_vis_fmul8sux16 (v8qi, v4hi);
v4hi __builtin_vis_fmul8ulx16 (v8qi, v4hi);
v2si __builtin_vis_fmuld8sux16 (v4qi, v2hi);
v2si __builtin_vis_fmuld8ulx16 (v4qi, v2hi);
v4qi __builtin_vis_fpack16 (v4hi);
v8qi __builtin_vis_fpack32 (v2si, v8qi);
v2hi __builtin_vis_fpackfix (v2si);
v8qi __builtin_vis_fpmerge (v4qi, v4qi);
int64_t __builtin_vis_pdist (v8qi, v8qi, int64_t);
long __builtin_vis_edge8 (void *, void *);
long __builtin_vis_edge8l (void *, void *);
long __builtin_vis_edge16 (void *, void *);
long __builtin_vis_edge16l (void *, void *);
long __builtin_vis_edge32 (void *, void *);
long __builtin_vis_edge32l (void *, void *);
long __builtin_vis_fcmple16 (v4hi, v4hi);
long __builtin_vis_fcmple32 (v2si, v2si);
long __builtin_vis_fcmpne16 (v4hi, v4hi);
long __builtin_vis_fcmpne32 (v2si, v2si);
long __builtin_vis_fcmpgt16 (v4hi, v4hi);
long __builtin_vis_fcmpgt32 (v2si, v2si);
long __builtin_vis_fcmpeq16 (v4hi, v4hi);
long __builtin_vis_fcmpeq32 (v2si, v2si);
v4hi __builtin_vis_fpadd16 (v4hi, v4hi);
v2hi __builtin_vis_fpadd16s (v2hi, v2hi);
v2si __builtin_vis_fpadd32 (v2si, v2si);
v1si __builtin_vis_fpadd32s (v1si, v1si);
v4hi __builtin_vis_fpsub16 (v4hi, v4hi);
v2hi __builtin_vis_fpsub16s (v2hi, v2hi);
v2si __builtin_vis_fpsub32 (v2si, v2si);
v1si __builtin_vis_fpsub32s (v1si, v1si);
long __builtin_vis_array8 (long, long);
long __builtin_vis_array16 (long, long);
long __builtin_vis_array32 (long, long);
When you use the -mvis2 switch, the VIS version 2.0 built-in functions also become available:
long __builtin_vis_bmask (long, long);
int64_t __builtin_vis_bshuffledi (int64_t, int64_t);
v2si __builtin_vis_bshufflev2si (v2si, v2si);
v4hi __builtin_vis_bshufflev2si (v4hi, v4hi);
v8qi __builtin_vis_bshufflev2si (v8qi, v8qi);
long __builtin_vis_edge8n (void *, void *);
long __builtin_vis_edge8ln (void *, void *);
long __builtin_vis_edge16n (void *, void *);
long __builtin_vis_edge16ln (void *, void *);
long __builtin_vis_edge32n (void *, void *);
long __builtin_vis_edge32ln (void *, void *);
When you use the -mvis3 switch, the VIS version 3.0 built-in functions also become available:
void __builtin_vis_cmask8 (long);
void __builtin_vis_cmask16 (long);
void __builtin_vis_cmask32 (long);
v4hi __builtin_vis_fchksm16 (v4hi, v4hi);
v4hi __builtin_vis_fsll16 (v4hi, v4hi);
v4hi __builtin_vis_fslas16 (v4hi, v4hi);
v4hi __builtin_vis_fsrl16 (v4hi, v4hi);
v4hi __builtin_vis_fsra16 (v4hi, v4hi);
v2si __builtin_vis_fsll16 (v2si, v2si);
v2si __builtin_vis_fslas16 (v2si, v2si);
v2si __builtin_vis_fsrl16 (v2si, v2si);
v2si __builtin_vis_fsra16 (v2si, v2si);
long __builtin_vis_pdistn (v8qi, v8qi);
v4hi __builtin_vis_fmean16 (v4hi, v4hi);
int64_t __builtin_vis_fpadd64 (int64_t, int64_t);
int64_t __builtin_vis_fpsub64 (int64_t, int64_t);
v4hi __builtin_vis_fpadds16 (v4hi, v4hi);
v2hi __builtin_vis_fpadds16s (v2hi, v2hi);
v4hi __builtin_vis_fpsubs16 (v4hi, v4hi);
v2hi __builtin_vis_fpsubs16s (v2hi, v2hi);
v2si __builtin_vis_fpadds32 (v2si, v2si);
v1si __builtin_vis_fpadds32s (v1si, v1si);
v2si __builtin_vis_fpsubs32 (v2si, v2si);
v1si __builtin_vis_fpsubs32s (v1si, v1si);
long __builtin_vis_fucmple8 (v8qi, v8qi);
long __builtin_vis_fucmpne8 (v8qi, v8qi);
long __builtin_vis_fucmpgt8 (v8qi, v8qi);
long __builtin_vis_fucmpeq8 (v8qi, v8qi);
float __builtin_vis_fhadds (float, float);
double __builtin_vis_fhaddd (double, double);
float __builtin_vis_fhsubs (float, float);
double __builtin_vis_fhsubd (double, double);
float __builtin_vis_fnhadds (float, float);
double __builtin_vis_fnhaddd (double, double);
int64_t __builtin_vis_umulxhi (int64_t, int64_t);
int64_t __builtin_vis_xmulx (int64_t, int64_t);
int64_t __builtin_vis_xmulxhi (int64_t, int64_t);
GCC provides extensions for the SPU processor as described in the Sony/Toshiba/IBM SPU Language Extensions Specification, which can be found at http://cell.scei.co.jp/ or http://www.ibm.com/developerworks/power/cell/. GCC's implementation differs in several ways.
signed or unsigned is omitted, the signedness of the
vector type is the default signedness of the base type. The default
varies depending on the operating system, so a portable program should
always specify the signedness.
__vector is added. The macro
vector is defined in <spu_intrinsics.h> and can be
undefined.
typedef name as the type specifier for a
vector type.
spu_add ((vector signed int){1, 2, 3, 4}, foo);
Since spu_add is a macro, the vector constant in the example
is treated as four separate arguments. Wrap the entire argument in
parentheses for this to work.
__builtin_expect is not supported.
Note: Only the interface described in the aforementioned specification is supported. Internally, GCC uses built-in functions to implement the required functionality, but these are not supported and are subject to change without notice.
GCC provides intrinsics to access certain instructions of the TI C6X
processors. These intrinsics, listed below, are available after
inclusion of the c6x_intrinsics.h header file. They map directly
to C6X instructions.
int _sadd (int, int)
int _ssub (int, int)
int _sadd2 (int, int)
int _ssub2 (int, int)
long long _mpy2 (int, int)
long long _smpy2 (int, int)
int _add4 (int, int)
int _sub4 (int, int)
int _saddu4 (int, int)
int _smpy (int, int)
int _smpyh (int, int)
int _smpyhl (int, int)
int _smpylh (int, int)
int _sshl (int, int)
int _subc (int, int)
int _avg2 (int, int)
int _avgu4 (int, int)
int _clrr (int, int)
int _extr (int, int)
int _extru (int, int)
int _abs (int)
int _abs2 (int)
GCC provides intrinsics to access every instruction of the TILE-Gx processor. The intrinsics are of the form:
unsigned long long __insn_op (...)
Where op is the name of the instruction. Refer to the ISA manual for the complete list of instructions.
GCC also provides intrinsics to directly access the network registers. The intrinsics are:
unsigned long long __tile_idn0_receive (void)
unsigned long long __tile_idn1_receive (void)
unsigned long long __tile_udn0_receive (void)
unsigned long long __tile_udn1_receive (void)
unsigned long long __tile_udn2_receive (void)
unsigned long long __tile_udn3_receive (void)
void __tile_idn_send (unsigned long long)
void __tile_udn_send (unsigned long long)
The intrinsic void __tile_network_barrier (void) is used to
guarantee that no network operatons before it will be reordered with
those after it.
GCC provides intrinsics to access every instruction of the TILEPro processor. The intrinsics are of the form:
unsigned __insn_op (...)
Where op is the name of the instruction. Refer to the ISA manual for the complete list of instructions.
GCC also provides intrinsics to directly access the network registers. The intrinsics are:
unsigned __tile_idn0_receive (void)
unsigned __tile_idn1_receive (void)
unsigned __tile_sn_receive (void)
unsigned __tile_udn0_receive (void)
unsigned __tile_udn1_receive (void)
unsigned __tile_udn2_receive (void)
unsigned __tile_udn3_receive (void)
void __tile_idn_send (unsigned)
void __tile_sn_send (unsigned)
void __tile_udn_send (unsigned)
The intrinsic void __tile_network_barrier (void) is used to
guarantee that no network operatons before it will be reordered with
those after it.
For some target machines, GCC supports additional options to the format attribute (see Declaring Attributes of Functions).
Solaris targets support the cmn_err (or __cmn_err__) format
check. cmn_err accepts a subset of the standard printf
conversions, and the two-argument %b conversion for displaying
bit-fields. See the Solaris man page for cmn_err for more information.
Darwin targets support the CFString (or __CFString__) in the format
attribute context. Declarations made with such attribution will be parsed for correct syntax
and format argument types. However, parsing of the format string itself is currently undefined
and will not be carried out by this version of the compiler.
Additionally, CFStringRefs (defined by the CoreFoundation headers) may
also be used as format arguments. Note that the relevant headers are only likely to be
available on Darwin (OSX) installations. On such installations, the XCode and system
documentation provide descriptions of CFString, CFStringRefs and
associated functions.
GCC supports several types of pragmas, primarily in order to compile code originally written for other compilers. Note that in general we do not recommend the use of pragmas; See Function Attributes, for further explanation.
The ARM target defines pragmas for controlling the default addition of
long_call and short_call attributes to functions.
See Function Attributes, for information about the effects of these
attributes.
long_callslong_call attribute.
no_long_callsshort_call attribute.
long_calls_offlong_call or short_call attributes of
subsequent functions.
GCC memregs number-memregs= for the current
file. Use with care! This pragma must be before any function in the
file, and mixing different memregs values in different objects may
make them incompatible. This pragma is useful when a
performance-critical function uses a memreg for temporary values,
as it may allow you to reduce the number of memregs used.
ADDRESS name address1234H numeric syntax is not supported (use 0x1234
instead). Example:
#pragma ADDRESS port3 0x103
char port3;
custom io_volatile (on|off)-mio-volatile for the current
file. Note that for compatibility with future GCC releases, this
option should only be used once before any io variables in each
file.
GCC coprocessor available registers#pragma GCC coprocessor available $c0...$c10, $c28
GCC coprocessor call_saved registers#pragma GCC coprocessor call_saved $c4...$c6, $c31
GCC coprocessor subclass '(A|B|C|D)' = registersasm constructs. registers may be a single
register, register range separated by ellipses, or comma-separated
list of those. Example:
#pragma GCC coprocessor subclass 'B' = $c2, $c4, $c6
asm ("cpfoo %0" : "=B" (x));
GCC disinterrupt name , name ... #pragma disinterrupt foo
#pragma disinterrupt bar, grill
int foo () { ... }
GCC call name , name ... extern int foo ();
#pragma call foo
The RS/6000 and PowerPC targets define one pragma for controlling
whether or not the longcall attribute is added to function
declarations by default. This pragma overrides the -mlongcall
option, but not the longcall and shortcall attributes.
See RS/6000 and PowerPC Options, for more information about when long
calls are and are not necessary.
longcall (1)longcall attribute to all subsequent function
declarations.
longcall (0)longcall attribute to subsequent function
declarations.
The following pragmas are available for all architectures running the Darwin operating system. These are useful for compatibility with other Mac OS compilers.
mark tokens...options align=alignmentmac68k, to emulate m68k alignment, or
power, to emulate PowerPC alignment. Uses of this pragma nest
properly; to restore the previous setting, use reset for the
alignment.
segment tokens...unused (var [, var]...)unused attribute, except that this pragma may appear
anywhere within the variables' scopes.
The Solaris target supports #pragma redefine_extname
(see Symbol-Renaming Pragmas). It also supports additional
#pragma directives for compatibility with the system compiler.
align alignment (variable [, variable]...)aligned attribute see Variable Attributes). Macro expansion occurs on the arguments to this pragma
when compiling C and Objective-C. It does not currently occur when
compiling C++, but this is a bug which may be fixed in a future
release.
fini (function [, function]...).fini section.
init (function [, function]...)main) or during shared module loading, by
adding a call to the .init section.
For compatibility with the Solaris and Tru64 UNIX system headers, GCC
supports two #pragma directives which change the name used in
assembly for a given declaration. #pragma extern_prefix is only
available on platforms whose system headers need it. To get this effect
on all platforms supported by GCC, use the asm labels extension (see Asm Labels).
redefine_extname oldname newname__PRAGMA_REDEFINE_EXTNAME
will be defined if this pragma is available (currently on all platforms).
extern_prefix stringextern_prefix pragma
whose argument is an empty string. The preprocessor macro
__PRAGMA_EXTERN_PREFIX will be defined if this pragma is
available (currently only on Tru64 UNIX).
These pragmas and the asm labels extension interact in a complicated manner. Here are some corner cases you may want to be aware of.
#pragma redefine_extname is
always the C-language name.
#pragma extern_prefix is in effect, and a declaration
occurs with an asm label attached, the prefix is silently ignored for
that declaration.
#pragma extern_prefix and #pragma redefine_extname
apply to the same declaration, whichever triggered first wins, and a
warning issues if they contradict each other. (We would like to have
#pragma redefine_extname always win, for consistency with asm
labels, but if #pragma extern_prefix triggers first we have no
way of knowing that that happened.)
For compatibility with Microsoft Windows compilers, GCC supports a
set of #pragma directives which change the maximum alignment of
members of structures (other than zero-width bitfields), unions, and
classes subsequently defined. The n value below always is required
to be a small power of two and specifies the new alignment in bytes.
#pragma pack(n) simply sets the new alignment.
#pragma pack() sets the alignment to the one that was in
effect when compilation started (see also command-line option
-fpack-struct[=n] see Code Gen Options).
#pragma pack(push[,n]) pushes the current alignment
setting on an internal stack and then optionally sets the new alignment.
#pragma pack(pop) restores the alignment setting to the one
saved at the top of the internal stack (and removes that stack entry).
Note that #pragma pack([n]) does not influence this internal
stack; thus it is possible to have #pragma pack(push) followed by
multiple #pragma pack(n) instances and finalized by a single
#pragma pack(pop).
Some targets, e.g. i386 and powerpc, support the ms_struct
#pragma which lays out a structure as the documented
__attribute__ ((ms_struct)).
#pragma ms_struct on turns on the layout for structures
declared.
#pragma ms_struct off turns off the layout for structures
declared.
#pragma ms_struct reset goes back to the default layout.
For compatibility with SVR4, GCC supports a set of #pragma
directives for declaring symbols to be weak, and defining weak
aliases.
#pragma weak symbol#pragma weak symbol1 = symbol2GCC allows the user to selectively enable or disable certain types of diagnostics, and change the kind of the diagnostic. For example, a project's policy might require that all sources compile with -Werror but certain files might have exceptions allowing specific types of warnings. Or, a project might selectively enable diagnostics and treat them as errors depending on which preprocessor macros are defined.
#pragma GCC diagnostic kind optionkind is ‘error’ to treat this diagnostic as an error, ‘warning’ to treat it like a warning (even if -Werror is in effect), or ‘ignored’ if the diagnostic is to be ignored. option is a double quoted string which matches the command-line option.
#pragma GCC diagnostic warning "-Wformat"
#pragma GCC diagnostic error "-Wformat"
#pragma GCC diagnostic ignored "-Wformat"
Note that these pragmas override any command-line options. GCC keeps
track of the location of each pragma, and issues diagnostics according
to the state as of that point in the source file. Thus, pragmas occurring
after a line do not affect diagnostics caused by that line.
#pragma GCC diagnostic push#pragma GCC diagnostic poppush, and restore to that point at each pop. If a
pop has no matching push, the command line options are
restored.
#pragma GCC diagnostic error "-Wuninitialized"
foo(a); /* error is given for this one */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wuninitialized"
foo(b); /* no diagnostic for this one */
#pragma GCC diagnostic pop
foo(c); /* error is given for this one */
#pragma GCC diagnostic pop
foo(d); /* depends on command line options */
GCC also offers a simple mechanism for printing messages during compilation.
#pragma message string#pragma message "Compiling " __FILE__ "..."
string may be parenthesized, and is printed with location information. For example,
#define DO_PRAGMA(x) _Pragma (#x)
#define TODO(x) DO_PRAGMA(message ("TODO - " #x))
TODO(Remember to fix this)
prints ‘/tmp/file.c:4: note: #pragma message: TODO - Remember to fix this’.
#pragma GCC visibility push(visibility)#pragma GCC visibility popIn C++, ‘#pragma GCC visibility’ affects only namespace-scope declarations. Class members and template specializations are not affected; if you want to override the visibility for a particular member or instantiation, you must use an attribute.
For compatibility with Microsoft Windows compilers, GCC supports ‘#pragma push_macro("macro_name")’ and ‘#pragma pop_macro("macro_name")’.
#pragma push_macro("macro_name")#pragma pop_macro("macro_name")For example:
#define X 1
#pragma push_macro("X")
#undef X
#define X -1
#pragma pop_macro("X")
int x [X];
In this example, the definition of X as 1 is saved by #pragma
push_macro and restored by #pragma pop_macro.
#pragma GCC target ("string"...)attribute((target("STRING"))) was specified for that
function. The parenthesis around the options is optional.
See Function Attributes, for more information about the
target attribute and the attribute syntax.
The #pragma GCC target attribute is not implemented in GCC versions earlier
than 4.4 for the i386/x86_64 and 4.6 for the PowerPC backends. At
present, it is not implemented for other backends.
#pragma GCC optimize ("string"...)attribute((optimize("STRING"))) was specified for that
function. The parenthesis around the options is optional.
See Function Attributes, for more information about the
optimize attribute and the attribute syntax.
The ‘#pragma GCC optimize’ pragma is not implemented in GCC versions earlier than 4.4.
#pragma GCC push_options#pragma GCC pop_optionsThe ‘#pragma GCC push_options’ and ‘#pragma GCC pop_options’ pragmas are not implemented in GCC versions earlier than 4.4.
#pragma GCC reset_options#pragma GCC target and
#pragma GCC optimize to use the default switches as specified
on the command line.
The ‘#pragma GCC reset_options’ pragma is not implemented in GCC versions earlier than 4.4.
As permitted by ISO C11 and for compatibility with other compilers, GCC allows you to define a structure or union that contains, as fields, structures and unions without names. For example:
struct {
int a;
union {
int b;
float c;
};
int d;
} foo;
In this example, the user would be able to access members of the unnamed
union with code like ‘foo.b’. Note that only unnamed structs and
unions are allowed, you may not have, for example, an unnamed
int.
You must never create such structures that cause ambiguous field definitions. For example, this structure:
struct {
int a;
struct {
int a;
};
} foo;
It is ambiguous which a is being referred to with ‘foo.a’.
The compiler gives errors for such constructs.
Unless -fms-extensions is used, the unnamed field must be a
structure or union definition without a tag (for example, ‘struct
{ int a; };’). If -fms-extensions is used, the field may
also be a definition with a tag such as ‘struct foo { int a;
};’, a reference to a previously defined structure or union such as
‘struct foo;’, or a reference to a typedef name for a
previously defined structure or union type.
The option -fplan9-extensions enables -fms-extensions as well as two other extensions. First, a pointer to a structure is automatically converted to a pointer to an anonymous field for assignments and function calls. For example:
struct s1 { int a; };
struct s2 { struct s1; };
extern void f1 (struct s1 *);
void f2 (struct s2 *p) { f1 (p); }
In the call to f1 inside f2, the pointer p is
converted into a pointer to the anonymous field.
Second, when the type of an anonymous field is a typedef for a
struct or union, code may refer to the field using the
name of the typedef.
typedef struct { int a; } s1;
struct s2 { s1; };
s1 f1 (struct s2 *p) { return p->s1; }
These usages are only permitted when they are not ambiguous.
Thread-local storage (TLS) is a mechanism by which variables are allocated such that there is one instance of the variable per extant thread. The run-time model GCC uses to implement this originates in the IA-64 processor-specific ABI, but has since been migrated to other processors as well. It requires significant support from the linker (ld), dynamic linker (ld.so), and system libraries (libc.so and libpthread.so), so it is not available everywhere.
At the user level, the extension is visible with a new storage
class keyword: __thread. For example:
__thread int i;
extern __thread struct state s;
static __thread char *p;
The __thread specifier may be used alone, with the extern
or static specifiers, but with no other storage class specifier.
When used with extern or static, __thread must appear
immediately after the other storage class specifier.
The __thread specifier may be applied to any global, file-scoped
static, function-scoped static, or static data member of a class. It may
not be applied to block-scoped automatic or non-static data member.
When the address-of operator is applied to a thread-local variable, it is evaluated at run-time and returns the address of the current thread's instance of that variable. An address so obtained may be used by any thread. When a thread terminates, any pointers to thread-local variables in that thread become invalid.
No static initialization may refer to the address of a thread-local variable.
In C++, if an initializer is present for a thread-local variable, it must be a constant-expression, as defined in 5.19.2 of the ANSI/ISO C++ standard.
See ELF Handling For Thread-Local Storage for a detailed explanation of the four thread-local storage addressing models, and how the run-time is expected to function.
The following are a set of changes to ISO/IEC 9899:1999 (aka C99) that document the exact semantics of the language extension.
Add new text after paragraph 1
Within either execution environment, a thread is a flow of control within a program. It is implementation defined whether or not there may be more than one thread associated with a program. It is implementation defined how threads beyond the first are created, the name and type of the function called at thread startup, and how threads may be terminated. However, objects with thread storage duration shall be initialized before thread startup.
Add new text before paragraph 3
An object whose identifier is declared with the storage-class
specifier __thread has thread storage duration.
Its lifetime is the entire execution of the thread, and its
stored value is initialized only once, prior to thread startup.
Add __thread.
Add __thread to the list of storage class specifiers in
paragraph 1.
Change paragraph 2 to
With the exception of__thread, at most one storage-class specifier may be given [...]. The__threadspecifier may be used alone, or immediately followingexternorstatic.
Add new text after paragraph 6
The declaration of an identifier for a variable that has block scope that specifies__threadshall also specify eitherexternorstatic.The
__threadspecifier shall be used only with variables.
The following are a set of changes to ISO/IEC 14882:1998 (aka C++98) that document the exact semantics of the language extension.
New text after paragraph 4
A thread is a flow of control within the abstract machine. It is implementation defined whether or not there may be more than one thread.
New text after paragraph 7
It is unspecified whether additional action must be taken to ensure when and whether side effects are visible to other threads.
Add __thread.
Add after paragraph 5
The thread that begins execution at themainfunction is called the main thread. It is implementation defined how functions beginning threads other than the main thread are designated or typed. A function so designated, as well as themainfunction, is called a thread startup function. It is implementation defined what happens if a thread startup function returns. It is implementation defined what happens to other threads when any thread callsexit.
Add after paragraph 4
The storage for an object of thread storage duration shall be statically initialized before the first statement of the thread startup function. An object of thread storage duration shall not require dynamic initialization.
Add after paragraph 3
The type of an object with thread storage duration shall not have a non-trivial destructor, nor shall it be an array type whose elements (directly or indirectly) have non-trivial destructors.
Add “thread storage duration” to the list in paragraph 1.
Change paragraph 2
Thread, static, and automatic storage durations are associated with objects introduced by declarations [...].
Add __thread to the list of specifiers in paragraph 3.
New section before [basic.stc.static]
The keyword__threadapplied to a non-local object gives the object thread storage duration.A local variable or class data member declared both
staticand__threadgives the variable or member thread storage duration.
Change paragraph 1
All objects which have neither thread storage duration, dynamic storage duration nor are local [...].
Add __thread to the list in paragraph 1.
Change paragraph 1
With the exception of__thread, at most one storage-class-specifier shall appear in a given decl-specifier-seq. The__threadspecifier may be used alone, or immediately following theexternorstaticspecifiers. [...]
Add after paragraph 5
The __thread specifier can be applied only to the names of objects
and to anonymous unions.
Add after paragraph 6
Non-staticmembers shall not be__thread.
Integer constants can be written as binary constants, consisting of a sequence of ‘0’ and ‘1’ digits, prefixed by ‘0b’ or ‘0B’. This is particularly useful in environments that operate a lot on the bit-level (like microcontrollers).
The following statements are identical:
i = 42;
i = 0x2a;
i = 052;
i = 0b101010;
The type of these constants follows the same rules as for octal or hexadecimal integer constants, so suffixes like ‘L’ or ‘UL’ can be applied.
The GNU compiler provides these extensions to the C++ language (and you
can also use most of the C language extensions in your C++ programs). If you
want to write code that checks whether these features are available, you can
test for the GNU compiler the same way as for C programs: check for a
predefined macro __GNUC__. You can also use __GNUG__ to
test specifically for GNU C++ (see Predefined Macros).
The C++ standard differs from the C standard in its treatment of volatile objects. It fails to specify what constitutes a volatile access, except to say that C++ should behave in a similar manner to C with respect to volatiles, where possible. However, the different lvalueness of expressions between C and C++ complicate the behavior. G++ behaves the same as GCC for volatile access, See Volatiles, for a description of GCC's behavior.
The C and C++ language specifications differ when an object is accessed in a void context:
volatile int *src = somevalue;
*src;
The C++ standard specifies that such expressions do not undergo lvalue to rvalue conversion, and that the type of the dereferenced object may be incomplete. The C++ standard does not specify explicitly that it is lvalue to rvalue conversion which is responsible for causing an access. There is reason to believe that it is, because otherwise certain simple expressions become undefined. However, because it would surprise most programmers, G++ treats dereferencing a pointer to volatile object of complete type as GCC would do for an equivalent type in C. When the object has incomplete type, G++ issues a warning; if you wish to force an error, you must force a conversion to rvalue with, for instance, a static cast.
When using a reference to volatile, G++ does not treat equivalent expressions as accesses to volatiles, but instead issues a warning that no volatile is accessed. The rationale for this is that otherwise it becomes difficult to determine where volatile access occur, and not possible to ignore the return value from functions returning volatile references. Again, if you wish to force a read, cast the reference to an rvalue.
G++ implements the same behavior as GCC does when assigning to a volatile object – there is no reread of the assigned-to object, the assigned rvalue is reused. Note that in C++ assignment expressions are lvalues, and if used as an lvalue, the volatile object will be referred to. For instance, vref will refer to vobj, as expected, in the following example:
volatile int vobj;
volatile int &vref = vobj = something;
As with the C front end, G++ understands the C99 feature of restricted pointers,
specified with the __restrict__, or __restrict type
qualifier. Because you cannot compile C++ by specifying the -std=c99
language flag, restrict is not a keyword in C++.
In addition to allowing restricted pointers, you can specify restricted references, which indicate that the reference is not aliased in the local context.
void fn (int *__restrict__ rptr, int &__restrict__ rref)
{
/* ... */
}
In the body of fn, rptr points to an unaliased integer and
rref refers to a (different) unaliased integer.
You may also specify whether a member function's this pointer is
unaliased by using __restrict__ as a member function qualifier.
void T::fn () __restrict__
{
/* ... */
}
Within the body of T::fn, this will have the effective
definition T *__restrict__ const this. Notice that the
interpretation of a __restrict__ member function qualifier is
different to that of const or volatile qualifier, in that it
is applied to the pointer rather than the object. This is consistent with
other compilers which implement restricted pointers.
As with all outermost parameter qualifiers, __restrict__ is
ignored in function definition matching. This means you only need to
specify __restrict__ in a function definition, rather than
in a function prototype as well.
There are several constructs in C++ which require space in the object file but are not clearly tied to a single translation unit. We say that these constructs have “vague linkage”. Typically such constructs are emitted wherever they are needed, though sometimes we can be more clever.
Local static variables and string constants used in an inline function
are also considered to have vague linkage, since they must be shared
between all inlined and out-of-line instances of the function.
Note: If the chosen key method is later defined as inline, the
vtable will still be emitted in every translation unit which defines it.
Make sure that any inline virtuals are declared inline in the class
body, even if they are not defined there.
type_info objectsWhen used with GNU ld version 2.8 or later on an ELF system such as GNU/Linux or Solaris 2, or on Microsoft Windows, duplicate copies of these constructs will be discarded at link time. This is known as COMDAT support.
On targets that don't support COMDAT, but do support weak symbols, GCC will use them. This way one copy will override all the others, but the unused copies will still take up space in the executable.
For targets which do not support either COMDAT or weak symbols, most entities with vague linkage will be emitted as local symbols to avoid duplicate definition errors from the linker. This will not happen for local statics in inlines, however, as having multiple copies will almost certainly break things.
See Declarations and Definitions in One Header, for another way to control placement of these constructs.
#pragma interface and #pragma implementation provide the
user with a way of explicitly directing the compiler to emit entities
with vague linkage (and debugging information) in a particular
translation unit.
Note: As of GCC 2.7.2, these #pragmas are not useful in
most cases, because of COMDAT support and the “key method” heuristic
mentioned in Vague Linkage. Using them can actually cause your
program to grow due to unnecessary out-of-line copies of inline
functions. Currently (3.4) the only benefit of these
#pragmas is reduced duplication of debugging information, and
that should be addressed soon on DWARF 2 targets with the use of
COMDAT groups.
#pragma interface#pragma interface "subdir/objects.h"The second form of this directive is useful for the case where you have
multiple headers with the same name in different directories. If you
use this form, you must specify the same string to ‘#pragma
implementation’.
#pragma implementation#pragma implementation "objects.h"If you use ‘#pragma implementation’ with no argument, it applies to an include file with the same basename4 as your source file. For example, in allclass.cc, giving just ‘#pragma implementation’ by itself is equivalent to ‘#pragma implementation "allclass.h"’.
In versions of GNU C++ prior to 2.6.0 allclass.h was treated as an implementation file whenever you would include it from allclass.cc even if you never specified ‘#pragma implementation’. This was deemed to be more trouble than it was worth, however, and disabled.
Use the string argument if you want a single implementation file to include code from multiple header files. (You must also use ‘#include’ to include the header file; ‘#pragma implementation’ only specifies how to use the file—it doesn't actually include it.)
There is no way to split up the contents of a single header file into multiple implementation files.
‘#pragma implementation’ and ‘#pragma interface’ also have an effect on function inlining.
If you define a class in a header file marked with ‘#pragma
interface’, the effect on an inline function defined in that class is
similar to an explicit extern declaration—the compiler emits
no code at all to define an independent version of the function. Its
definition is used only for inlining with its callers.
Conversely, when you include the same header file in a main source file that declares it as ‘#pragma implementation’, the compiler emits code for the function itself; this defines a version of the function that can be found via pointers (or by callers compiled without inlining). If all calls to the function can be inlined, you can avoid emitting the function by compiling with -fno-implement-inlines. If any calls were not inlined, you will get linker errors.
C++ templates are the first language feature to require more intelligence from the environment than one usually finds on a UNIX system. Somehow the compiler and linker have to make sure that each template instance occurs exactly once in the executable if it is needed, and not at all otherwise. There are two basic approaches to this problem, which are referred to as the Borland model and the Cfront model.
When used with GNU ld version 2.8 or later on an ELF system such as GNU/Linux or Solaris 2, or on Microsoft Windows, G++ supports the Borland model. On other systems, G++ implements neither automatic model.
A future version of G++ will support a hybrid model whereby the compiler will emit any instantiations for which the template definition is included in the compile, and store template definitions and instantiation context information into the object file for the rest. The link wrapper will extract that information as necessary and invoke the compiler to produce the remaining instantiations. The linker will then combine duplicate instantiations.
In the mean time, you have the following options for dealing with template instantiations:
This is your best option for application code written for the Borland
model, as it will just work. Code written for the Cfront model will
need to be modified so that the template definitions are available at
one or more points of instantiation; usually this is as simple as adding
#include <tmethods.cc> to the end of each template header.
For library code, if you want the library to provide all of the template instantiations it needs, just try to link all of its object files together; the link will fail, but cause the instantiations to be generated as a side effect. Be warned, however, that this may cause conflicts if multiple libraries try to provide the same instantiations. For greater control, use explicit instantiation as described in the next option.
#include "Foo.h"
#include "Foo.cc"
template class Foo<int>;
template ostream& operator <<
(ostream&, const Foo<int>&);
for each of the instances you need, and create a template instantiation library from those.
If you are using Cfront-model code, you can probably get away with not using -fno-implicit-templates when compiling files that don't ‘#include’ the member template definitions.
If you use one big file to do the instantiations, you may want to compile it without -fno-implicit-templates so you get all of the instances required by your explicit instantiations (but not by any other files) without having to specify them as well.
G++ has extended the template instantiation syntax given in the ISO
standard to allow forward declaration of explicit instantiations
(with extern), instantiation of the compiler support data for a
template class (i.e. the vtable) without instantiating any of its
members (with inline), and instantiation of only the static data
members of a template class, without the support data or member
functions (with (static):
extern template int max (int, int);
inline template class Foo<int>;
static template class Foo<int>;
In C++, pointer to member functions (PMFs) are implemented using a wide pointer of sorts to handle all the possible call mechanisms; the PMF needs to store information about how to adjust the ‘this’ pointer, and if the function pointed to is virtual, where to find the vtable, and where in the vtable to look for the member function. If you are using PMFs in an inner loop, you should really reconsider that decision. If that is not an option, you can extract the pointer to the function that would be called for a given object/PMF pair and call it directly inside the inner loop, to save a bit of time.
Note that you will still be paying the penalty for the call through a function pointer; on most modern architectures, such a call defeats the branch prediction features of the CPU. This is also true of normal virtual function calls.
The syntax for this extension is
extern A a;
extern int (A::*fp)();
typedef int (*fptr)(A *);
fptr p = (fptr)(a.*fp);
For PMF constants (i.e. expressions of the form ‘&Klasse::Member’), no object is needed to obtain the address of the function. They can be converted to function pointers directly:
fptr p1 = (fptr)(&A::foo);
You must specify -Wno-pmf-conversions to use this extension.
Some attributes only make sense for C++ programs.
init_priority (priority)In Standard C++, objects defined at namespace scope are guaranteed to be
initialized in an order in strict accordance with that of their definitions
in a given translation unit. No guarantee is made for initializations
across translation units. However, GNU C++ allows users to control the
order of initialization of objects defined at namespace scope with the
init_priority attribute by specifying a relative priority,
a constant integral expression currently bounded between 101 and 65535
inclusive. Lower numbers indicate a higher priority.
In the following example, A would normally be created before
B, but the init_priority attribute has reversed that order:
Some_Class A __attribute__ ((init_priority (2000)));
Some_Class B __attribute__ ((init_priority (543)));
Note that the particular values of priority do not matter; only their
relative ordering.
java_interfaceextern "Java" block.
Calls to methods declared in this interface will be dispatched using GCJ's
interface table mechanism, instead of regular virtual table dispatch.
See also Namespace Association.
Caution: The semantics of this extension are not fully defined. Users should refrain from using this extension as its semantics may change subtly over time. It is possible that this extension will be removed in future versions of G++.
A using-directive with __attribute ((strong)) is stronger
than a normal using-directive in two ways:
The used namespace must be nested within the using namespace so that normal unqualified lookup works properly.
This is useful for composing a namespace transparently from implementation namespaces. For example:
namespace std {
namespace debug {
template <class T> struct A { };
}
using namespace debug __attribute ((__strong__));
template <> struct A<int> { }; // ok to specialize
template <class T> void f (A<T>);
}
int main()
{
f (std::A<float>()); // lookup finds std::f
f (std::A<int>());
}
The C++ front-end implements syntactic extensions that allow to determine at compile time various characteristics of a type (or of a pair of types).
__has_nothrow_assign (type)type is const qualified or is a reference type then the trait is
false. Otherwise if __has_trivial_assign (type) is true then the trait
is true, else if type is a cv class or union type with copy assignment
operators that are known not to throw an exception then the trait is true,
else it is false. Requires: type shall be a complete type,
(possibly cv-qualified) void, or an array of unknown bound.
__has_nothrow_copy (type)__has_trivial_copy (type) is true then the trait is true, else if
type is a cv class or union type with copy constructors that
are known not to throw an exception then the trait is true, else it is false.
Requires: type shall be a complete type, (possibly cv-qualified)
void, or an array of unknown bound.
__has_nothrow_constructor (type)__has_trivial_constructor (type) is true then the trait is
true, else if type is a cv class or union type (or array
thereof) with a default constructor that is known not to throw an
exception then the trait is true, else it is false. Requires:
type shall be a complete type, (possibly cv-qualified)
void, or an array of unknown bound.
__has_trivial_assign (type)type is const qualified or is a reference type then the trait is
false. Otherwise if __is_pod (type) is true then the trait is
true, else if type is a cv class or union type with a trivial
copy assignment ([class.copy]) then the trait is true, else it is
false. Requires: type shall be a complete type, (possibly
cv-qualified) void, or an array of unknown bound.
__has_trivial_copy (type)__is_pod (type) is true or type is a reference type
then the trait is true, else if type is a cv class or union type
with a trivial copy constructor ([class.copy]) then the trait
is true, else it is false. Requires: type shall be a complete
type, (possibly cv-qualified) void, or an array of unknown bound.
__has_trivial_constructor (type)__is_pod (type) is true then the trait is true, else if
type is a cv class or union type (or array thereof) with a
trivial default constructor ([class.ctor]) then the trait is true,
else it is false. Requires: type shall be a complete
type, (possibly cv-qualified) void, or an array of unknown bound.
__has_trivial_destructor (type)__is_pod (type) is true or type is a reference type then
the trait is true, else if type is a cv class or union type (or
array thereof) with a trivial destructor ([class.dtor]) then the trait
is true, else it is false. Requires: type shall be a complete
type, (possibly cv-qualified) void, or an array of unknown bound.
__has_virtual_destructor (type)type is a class type with a virtual destructor
([class.dtor]) then the trait is true, else it is false. Requires:
type shall be a complete type, (possibly cv-qualified)
void, or an array of unknown bound.
__is_abstract (type)type is an abstract class ([class.abstract]) then the trait
is true, else it is false. Requires: type shall be a complete
type, (possibly cv-qualified) void, or an array of unknown bound.
__is_base_of (base_type, derived_type)base_type is a base class of derived_type
([class.derived]) then the trait is true, otherwise it is false.
Top-level cv qualifications of base_type and
derived_type are ignored. For the purposes of this trait, a
class type is considered is own base. Requires: if __is_class
(base_type) and __is_class (derived_type) are true and
base_type and derived_type are not the same type
(disregarding cv-qualifiers), derived_type shall be a complete
type. Diagnostic is produced if this requirement is not met.
__is_class (type)type is a cv class type, and not a union type
([basic.compound]) the trait is true, else it is false.
__is_empty (type)__is_class (type) is false then the trait is false.
Otherwise type is considered empty if and only if: type
has no non-static data members, or all non-static data members, if
any, are bit-fields of length 0, and type has no virtual
members, and type has no virtual base classes, and type
has no base classes base_type for which
__is_empty (base_type) is false. Requires: type shall
be a complete type, (possibly cv-qualified) void, or an array
of unknown bound.
__is_enum (type)type is a cv enumeration type ([basic.compound]) the trait is
true, else it is false.
__is_literal_type (type)type is a literal type ([basic.types]) the trait is
true, else it is false. Requires: type shall be a complete type,
(possibly cv-qualified) void, or an array of unknown bound.
__is_pod (type)type is a cv POD type ([basic.types]) then the trait is true,
else it is false. Requires: type shall be a complete type,
(possibly cv-qualified) void, or an array of unknown bound.
__is_polymorphic (type)type is a polymorphic class ([class.virtual]) then the trait
is true, else it is false. Requires: type shall be a complete
type, (possibly cv-qualified) void, or an array of unknown bound.
__is_standard_layout (type)type is a standard-layout type ([basic.types]) the trait is
true, else it is false. Requires: type shall be a complete
type, (possibly cv-qualified) void, or an array of unknown bound.
__is_trivial (type)type is a trivial type ([basic.types]) the trait is
true, else it is false. Requires: type shall be a complete
type, (possibly cv-qualified) void, or an array of unknown bound.
__is_union (type)type is a cv union type ([basic.compound]) the trait is
true, else it is false.
__underlying_type (type)type. Requires: type shall be
an enumeration type ([dcl.enum]).
The Java language uses a slightly different exception handling model from C++. Normally, GNU C++ will automatically detect when you are writing C++ code that uses Java exceptions, and handle them appropriately. However, if C++ code only needs to execute destructors when Java exceptions are thrown through it, GCC will guess incorrectly. Sample problematic code is:
struct S { ~S(); };
extern void bar(); // is written in Java, and may throw exceptions
void foo()
{
S s;
bar();
}
The usual effect of an incorrect guess is a link failure, complaining of a missing routine called ‘__gxx_personality_v0’.
You can inform the compiler that Java exceptions are to be used in a translation unit, irrespective of what it might think, by writing ‘#pragma GCC java_exceptions’ at the head of the file. This ‘#pragma’ must appear before any functions that throw or catch exceptions, or run destructors when exceptions are thrown through them.
You cannot mix Java and C++ exceptions in the same translation unit. It is believed to be safe to throw a C++ exception from one file through another file compiled for the Java exception model, or vice versa, but there may be bugs in this area.
In the past, the GNU C++ compiler was extended to experiment with new features, at a time when the C++ language was still evolving. Now that the C++ standard is complete, some of those features are superseded by superior alternatives. Using the old features might cause a warning in some cases that the feature will be dropped in the future. In other cases, the feature might be gone already.
While the list below is not exhaustive, it documents some of the options that are now deprecated:
-fexternal-templates-falt-external-templates-fstrict-prototype-fno-strict-prototypeG++ allows a virtual function returning ‘void *’ to be overridden by one returning a different pointer type. This extension to the covariant return type rules is now deprecated and will be removed from a future version.
The G++ minimum and maximum operators (‘<?’ and ‘>?’) and
their compound forms (‘<?=’) and ‘>?=’) have been deprecated
and are now removed from G++. Code using these operators should be
modified to use std::min and std::max instead.
The named return value extension has been deprecated, and is now removed from G++.
The use of initializer lists with new expressions has been deprecated, and is now removed from G++.
Floating and complex non-type template parameters have been deprecated, and are now removed from G++.
The implicit typename extension has been deprecated and is now removed from G++.
The use of default arguments in function pointers, function typedefs and other places where they are not permitted by the standard is deprecated and will be removed from a future version of G++.
G++ allows floating-point literals to appear in integral constant expressions, e.g. ‘ enum E { e = int(2.2 * 3.7) } ’ This extension is deprecated and will be removed from a future version.
G++ allows static data members of const floating-point type to be declared with an initializer in a class definition. The standard only allows initializers for static members of const integral types and const enumeration types so this extension has been deprecated and will be removed from a future version.
Now that there is a definitive ISO standard C++, G++ has a specification to adhere to. The C++ language evolved over time, and features that used to be acceptable in previous drafts of the standard, such as the ARM [Annotated C++ Reference Manual], are no longer accepted. In order to allow compilation of C++ written to such drafts, G++ contains some backwards compatibilities. All such backwards compatibility features are liable to disappear in future versions of G++. They should be considered deprecated. See Deprecated Features.
For scopeImplicit C languageextern "C" {...}
scope to set the language. On such systems, all header files are
implicitly scoped inside a C language scope. Also, an empty prototype
() will be treated as an unspecified number of arguments, rather
than no arguments, as C++ demands.
This document is meant to describe some of the GNU Objective-C features. It is not intended to teach you Objective-C. There are several resources on the Internet that present the language.
This section is specific for the GNU Objective-C runtime. If you are using a different runtime, you can skip it.
The GNU Objective-C runtime provides an API that allows you to interact with the Objective-C runtime system, querying the live runtime structures and even manipulating them. This allows you for example to inspect and navigate classes, methods and protocols; to define new classes or new methods, and even to modify existing classes or protocols.
If you are using a “Foundation” library such as GNUstep-Base, this library will provide you with a rich set of functionality to do most of the inspection tasks, and you probably will only need direct access to the GNU Objective-C runtime API to define new classes or methods.
The GNU Objective-C runtime provides an API which is similar to the one provided by the “Objective-C 2.0” Apple/NeXT Objective-C runtime. The API is documented in the public header files of the GNU Objective-C runtime:
id, Class
and BOOL. You have to include this header to do almost
anything with Objective-C.
class_getName(), declared in
objc/runtime.h.
@synchronized() syntax, allowing
you to emulate an Objective-C @synchronized() block in plain
C/C++ code.
objc_mutex_lock(), which provide a
platform-independent set of threading functions.
The header files contain detailed documentation for each function in the GNU Objective-C runtime API.
The GNU Objective-C runtime used to provide a different API, which we
call the “traditional” GNU Objective-C runtime API. Functions
belonging to this API are easy to recognize because they use a
different naming convention, such as class_get_super_class()
(traditional API) instead of class_getSuperclass() (modern
API). Software using this API includes the file
objc/objc-api.h where it is declared.
Starting with GCC 4.7.0, the traditional GNU runtime API is no longer available.
+load: Executing code before mainThis section is specific for the GNU Objective-C runtime. If you are using a different runtime, you can skip it.
The GNU Objective-C runtime provides a way that allows you to execute
code before the execution of the program enters the main
function. The code is executed on a per-class and a per-category basis,
through a special class method +load.
This facility is very useful if you want to initialize global variables
which can be accessed by the program directly, without sending a message
to the class first. The usual way to initialize global variables, in the
+initialize method, might not be useful because
+initialize is only called when the first message is sent to a
class object, which in some cases could be too late.
Suppose for example you have a FileStream class that declares
Stdin, Stdout and Stderr as global variables, like
below:
FileStream *Stdin = nil;
FileStream *Stdout = nil;
FileStream *Stderr = nil;
@implementation FileStream
+ (void)initialize
{
Stdin = [[FileStream new] initWithFd:0];
Stdout = [[FileStream new] initWithFd:1];
Stderr = [[FileStream new] initWithFd:2];
}
/* Other methods here */
@end
In this example, the initialization of Stdin, Stdout and
Stderr in +initialize occurs too late. The programmer can
send a message to one of these objects before the variables are actually
initialized, thus sending messages to the nil object. The
+initialize method which actually initializes the global
variables is not invoked until the first message is sent to the class
object. The solution would require these variables to be initialized
just before entering main.
The correct solution of the above problem is to use the +load
method instead of +initialize:
@implementation FileStream
+ (void)load
{
Stdin = [[FileStream new] initWithFd:0];
Stdout = [[FileStream new] initWithFd:1];
Stderr = [[FileStream new] initWithFd:2];
}
/* Other methods here */
@end
The +load is a method that is not overridden by categories. If a
class and a category of it both implement +load, both methods are
invoked. This allows some additional initializations to be performed in
a category.
This mechanism is not intended to be a replacement for +initialize.
You should be aware of its limitations when you decide to use it
instead of +initialize.
+load+load is to be used only as a last resort. Because it is
executed very early, most of the Objective-C runtime machinery will
not be ready when +load is executed; hence +load works
best for executing C code that is independent on the Objective-C
runtime.
The +load implementation in the GNU runtime guarantees you the
following things:
+load implementation of all super classes of a class are
executed before the +load of that class is executed;
+load implementation of a class is executed before the
+load implementation of any category.
In particular, the following things, even if they can work in a particular case, are not guaranteed:
@"this is a
constant string");
You should make no assumptions about receiving +load in sibling
classes when you write +load of a class. The order in which
sibling classes receive +load is not guaranteed.
The order in which +load and +initialize are called could
be problematic if this matters. If you don't allocate objects inside
+load, it is guaranteed that +load is called before
+initialize. If you create an object inside +load the
+initialize method of object's class is invoked even if
+load was not invoked. Note if you explicitly call +load
on a class, +initialize will be called first. To avoid possible
problems try to implement only one of these methods.
The +load method is also invoked when a bundle is dynamically
loaded into your running program. This happens automatically without any
intervening operation from you. When you write bundles and you need to
write +load you can safely create and send messages to objects whose
classes already exist in the running program. The same restrictions as
above apply to classes defined in bundle.
This is an advanced section. Type encodings are used extensively by the compiler and by the runtime, but you generally do not need to know about them to use Objective-C.
The Objective-C compiler generates type encodings for all the types. These type encodings are used at runtime to find out information about selectors and methods and about objects and classes.
The types are encoded in the following way:
_Bool
| B
|
char
| c
|
unsigned char
| C
|
short
| s
|
unsigned short
| S
|
int
| i
|
unsigned int
| I
|
long
| l
|
unsigned long
| L
|
long long
| q
|
unsigned long long
| Q
|
float
| f
|
double
| d
|
long double
| D
|
void
| v
|
id
| @
|
Class
| #
|
SEL
| :
|
char*
| *
|
enum
| an enum is encoded exactly as the integer type that the compiler uses for it, which depends on the enumeration
values. Often the compiler users unsigned int, which is then encoded as I.
|
| unknown type | ?
|
| Complex types | j followed by the inner type. For example _Complex double is encoded as "jd".
|
| bit-fields | b followed by the starting position of the bit-field, the type of the bit-field and the size of the bit-field (the bit-fields encoding was changed from the NeXT's compiler encoding, see below)
|
The encoding of bit-fields has changed to allow bit-fields to be properly handled by the runtime functions that compute sizes and alignments of types that contain bit-fields. The previous encoding contained only the size of the bit-field. Using only this information it is not possible to reliably compute the size occupied by the bit-field. This is very important in the presence of the Boehm's garbage collector because the objects are allocated using the typed memory facility available in this collector. The typed memory allocation requires information about where the pointers are located inside the object.
The position in the bit-field is the position, counting in bits, of the bit closest to the beginning of the structure.
The non-atomic types are encoded as follows:
| pointers | ‘^’ followed by the pointed type.
|
| arrays | ‘[’ followed by the number of elements in the array followed by the type of the elements followed by ‘]’
|
| structures | ‘{’ followed by the name of the structure (or ‘?’ if the structure is unnamed), the ‘=’ sign, the type of the members and by ‘}’
|
| unions | ‘(’ followed by the name of the structure (or ‘?’ if the union is unnamed), the ‘=’ sign, the type of the members followed by ‘)’
|
| vectors | ‘![’ followed by the vector_size (the number of bytes composing the vector) followed by a comma, followed by the alignment (in bytes) of the vector, followed by the type of the elements followed by ‘]’
|
Here are some types and their encodings, as they are generated by the compiler on an i386 machine:
| Objective-C type | Compiler encoding
|
int a[10]; | [10i]
|
struct {
int i;
float f[3];
int a:3;
int b:2;
char c;
}
| {?=i[3f]b128i3b131i2c}
|
int a __attribute__ ((vector_size (16))); | ![16,16i] (alignment would depend on the machine)
|
In addition to the types the compiler also encodes the type specifiers. The table below describes the encoding of the current Objective-C type specifiers:
| Specifier | Encoding
|
const
| r
|
in
| n
|
inout
| N
|
out
| o
|
bycopy
| O
|
byref
| R
|
oneway
| V
|
The type specifiers are encoded just before the type. Unlike types however, the type specifiers are only encoded when they appear in method argument types.
Note how const interacts with pointers:
| Objective-C type | Compiler encoding
|
const int | ri
|
const int* | ^ri
|
int *const | r^i
|
const int* is a pointer to a const int, and so is
encoded as ^ri. int* const, instead, is a const
pointer to an int, and so is encoded as r^i.
Finally, there is a complication when encoding const char *
versus char * const. Because char * is encoded as
* and not as ^c, there is no way to express the fact
that r applies to the pointer or to the pointee.
Hence, it is assumed as a convention that r* means const
char * (since it is what is most often meant), and there is no way to
encode char *const. char *const would simply be encoded
as *, and the const is lost.
Unfortunately, historically GCC used to have a number of bugs in its encoding code. The NeXT runtime expects GCC to emit type encodings in this historical format (compatible with GCC-3.3), so when using the NeXT runtime, GCC will introduce on purpose a number of incorrect encodings:
enums are always encoded as 'i' (int) even if they are actually
unsigned or long.
In addition to that, the NeXT runtime uses a different encoding for
bitfields. It encodes them as b followed by the size, without
a bit offset or the underlying field type.
GNU Objective-C supports the @encode syntax that allows you to
create a type encoding from a C/Objective-C type. For example,
@encode(int) is compiled by the compiler into "i".
@encode does not support type qualifiers other than
const. For example, @encode(const char*) is valid and
is compiled into "r*", while @encode(bycopy char *) is
invalid and will cause a compilation error.
This section documents the encoding of method types, which is rarely needed to use Objective-C. You should skip it at a first reading; the runtime provides functions that will work on methods and can walk through the list of parameters and interpret them for you. These functions are part of the public “API” and are the preferred way to interact with method signatures from user code.
But if you need to debug a problem with method signatures and need to know how they are implemented (i.e., the “ABI”), read on.
Methods have their “signature” encoded and made available to the runtime. The “signature” encodes all the information required to dynamically build invocations of the method at runtime: return type and arguments.
The “signature” is a null-terminated string, composed of the following:
int would have i here.
self and the
method selector _cmd).
For example, a method with no arguments and returning int would
have the signature i8@0:4 if the size of a pointer is 4. The
signature is interpreted as follows: the i is the return type
(an int), the 8 is the total size of the parameters in
bytes (two pointers each of size 4), the @0 is the first
parameter (an object at byte offset 0) and :4 is the
second parameter (a SEL at byte offset 4).
You can easily find more examples by running the “strings” program
on an Objective-C object file compiled by GCC. You'll see a lot of
strings that look very much like i8@0:4. They are signatures
of Objective-C methods.
This section is specific for the GNU Objective-C runtime. If you are using a different runtime, you can skip it.
Support for garbage collection with the GNU runtime has been added by using a powerful conservative garbage collector, known as the Boehm-Demers-Weiser conservative garbage collector.
To enable the support for it you have to configure the compiler using an additional argument, --enable-objc-gc. This will build the boehm-gc library, and build an additional runtime library which has several enhancements to support the garbage collector. The new library has a new name, libobjc_gc.a to not conflict with the non-garbage-collected library.
When the garbage collector is used, the objects are allocated using the so-called typed memory allocation mechanism available in the Boehm-Demers-Weiser collector. This mode requires precise information on where pointers are located inside objects. This information is computed once per class, immediately after the class has been initialized.
There is a new runtime function class_ivar_set_gcinvisible()
which can be used to declare a so-called weak pointer
reference. Such a pointer is basically hidden for the garbage collector;
this can be useful in certain situations, especially when you want to
keep track of the allocated objects, yet allow them to be
collected. This kind of pointers can only be members of objects, you
cannot declare a global pointer as a weak reference. Every type which is
a pointer type can be declared a weak pointer, including id,
Class and SEL.
Here is an example of how to use this feature. Suppose you want to implement a class whose instances hold a weak pointer reference; the following class does this:
@interface WeakPointer : Object
{
const void* weakPointer;
}
- initWithPointer:(const void*)p;
- (const void*)weakPointer;
@end
@implementation WeakPointer
+ (void)initialize
{
if (self == objc_lookUpClass ("WeakPointer"))
class_ivar_set_gcinvisible (self, "weakPointer", YES);
}
- initWithPointer:(const void*)p
{
weakPointer = p;
return self;
}
- (const void*)weakPointer
{
return weakPointer;
}
@end
Weak pointers are supported through a new type character specifier
represented by the ‘!’ character. The
class_ivar_set_gcinvisible() function adds or removes this
specifier to the string type description of the instance variable named
as argument.
GNU Objective-C provides constant string objects that are generated directly by the compiler. You declare a constant string object by prefixing a C constant string with the character ‘@’:
id myString = @"this is a constant string object";
The constant string objects are by default instances of the
NXConstantString class which is provided by the GNU Objective-C
runtime. To get the definition of this class you must include the
objc/NXConstStr.h header file.
User defined libraries may want to implement their own constant string
class. To be able to support them, the GNU Objective-C compiler provides
a new command line options -fconstant-string-class=class-name.
The provided class should adhere to a strict structure, the same
as NXConstantString's structure:
@interface MyConstantStringClass
{
Class isa;
char *c_string;
unsigned int len;
}
@end
NXConstantString inherits from Object; user class
libraries may choose to inherit the customized constant string class
from a different class than Object. There is no requirement in
the methods the constant string class has to implement, but the final
ivar layout of the class must be the compatible with the given
structure.
When the compiler creates the statically allocated constant string
object, the c_string field will be filled by the compiler with
the string; the length field will be filled by the compiler with
the string length; the isa pointer will be filled with
NULL by the compiler, and it will later be fixed up automatically
at runtime by the GNU Objective-C runtime library to point to the class
which was set by the -fconstant-string-class option when the
object file is loaded (if you wonder how it works behind the scenes, the
name of the class to use, and the list of static objects to fixup, are
stored by the compiler in the object file in a place where the GNU
runtime library will find them at runtime).
As a result, when a file is compiled with the -fconstant-string-class option, all the constant string objects will be instances of the class specified as argument to this option. It is possible to have multiple compilation units referring to different constant string classes, neither the compiler nor the linker impose any restrictions in doing this.
The keyword @compatibility_alias allows you to define a class name
as equivalent to another class name. For example:
@compatibility_alias WOApplication GSWApplication;
tells the compiler that each time it encounters WOApplication as
a class name, it should replace it with GSWApplication (that is,
WOApplication is just an alias for GSWApplication).
There are some constraints on how this can be used—
WOApplication (the alias) must not be an existing class;
GSWApplication (the real class) must be an existing class.
GNU Objective-C provides exception support built into the language, as in the following example:
@try {
...
@throw expr;
...
}
@catch (AnObjCClass *exc) {
...
@throw expr;
...
@throw;
...
}
@catch (AnotherClass *exc) {
...
}
@catch (id allOthers) {
...
}
@finally {
...
@throw expr;
...
}
The @throw statement may appear anywhere in an Objective-C or
Objective-C++ program; when used inside of a @catch block, the
@throw may appear without an argument (as shown above), in
which case the object caught by the @catch will be rethrown.
Note that only (pointers to) Objective-C objects may be thrown and
caught using this scheme. When an object is thrown, it will be caught
by the nearest @catch clause capable of handling objects of
that type, analogously to how catch blocks work in C++ and
Java. A @catch(id ...) clause (as shown above) may also
be provided to catch any and all Objective-C exceptions not caught by
previous @catch clauses (if any).
The @finally clause, if present, will be executed upon exit
from the immediately preceding @try ... @catch section.
This will happen regardless of whether any exceptions are thrown,
caught or rethrown inside the @try ... @catch section,
analogously to the behavior of the finally clause in Java.
There are several caveats to using the new exception mechanism:
NS_HANDLER-style idioms provided by the
NSException class, the new exceptions can only be used on Mac
OS X 10.3 (Panther) and later systems, due to additional functionality
needed in the NeXT Objective-C runtime.
@throw an exception
from Objective-C and catch it in C++, or vice versa
(i.e., throw ... @catch).
GNU Objective-C provides support for synchronized blocks:
@synchronized (ObjCClass *guard) {
...
}
Upon entering the @synchronized block, a thread of execution
shall first check whether a lock has been placed on the corresponding
guard object by another thread. If it has, the current thread
shall wait until the other thread relinquishes its lock. Once
guard becomes available, the current thread will place its own
lock on it, execute the code contained in the @synchronized
block, and finally relinquish the lock (thereby making guard
available to other threads).
Unlike Java, Objective-C does not allow for entire methods to be
marked @synchronized. Note that throwing exceptions out of
@synchronized blocks is allowed, and will cause the guarding
object to be unlocked properly.
Because of the interactions between synchronization and exception
handling, you can only use @synchronized when compiling with
exceptions enabled, that is with the command line option
-fobjc-exceptions.
GNU Objective-C provides support for the fast enumeration syntax:
id array = ...;
id object;
for (object in array)
{
/* Do something with 'object' */
}
array needs to be an Objective-C object (usually a collection
object, for example an array, a dictionary or a set) which implements
the “Fast Enumeration Protocol” (see below). If you are using a
Foundation library such as GNUstep Base or Apple Cocoa Foundation, all
collection objects in the library implement this protocol and can be
used in this way.
The code above would iterate over all objects in array. For
each of them, it assigns it to object, then executes the
Do something with 'object' statements.
Here is a fully worked-out example using a Foundation library (which
provides the implementation of NSArray, NSString and
NSLog):
NSArray *array = [NSArray arrayWithObjects: @"1", @"2", @"3", nil];
NSString *object;
for (object in array)
NSLog (@"Iterating over %@", object);
A c99-like declaration syntax is also allowed:
id array = ...;
for (id object in array)
{
/* Do something with 'object' */
}
this is completely equivalent to:
id array = ...;
{
id object;
for (object in array)
{
/* Do something with 'object' */
}
}
but can save some typing.
Note that the option -std=c99 is not required to allow this syntax in Objective-C.
Here is a more technical description with the gory details. Consider the code
for (object expression in collection expression)
{
statements
}
here is what happens when you run it:
for (object in [NSDictionary
keyEnumerator]) ....
nil and the loop
immediately terminates.
break and continue
commands, which will abort the iteration or skip to the next loop
iteration as expected.
nil. This allows
you to determine whether the iteration finished because a break
command was used (in which case object expression will remain
set to the last object that was iterated over) or because it iterated
over all the objects (in which case object expression will be
set to nil).
objc_enumerationMutation, a runtime
function that normally aborts the program but which can be customized
by Foundation libraries via objc_set_mutation_handler to do
something different, such as raising an exception.
If you want your own collection object to be usable with fast enumeration, you need to have it implement the method
- (unsigned long) countByEnumeratingWithState: (NSFastEnumerationState *)state
objects: (id *)objects
count: (unsigned long)len;
where NSFastEnumerationState must be defined in your code as follows:
typedef struct
{
unsigned long state;
id *itemsPtr;
unsigned long *mutationsPtr;
unsigned long extra[5];
} NSFastEnumerationState;
If no NSFastEnumerationState is defined in your code, the
compiler will automatically replace NSFastEnumerationState *
with struct __objcFastEnumerationState *, where that type is
silently defined by the compiler in an identical way. This can be
confusing and we recommend that you define
NSFastEnumerationState (as shown above) instead.
The method is called repeatedly during a fast enumeration to retrieve batches of objects. Each invocation of the method should retrieve the next batch of objects.
The return value of the method is the number of objects in the current
batch; this should not exceed len, which is the maximum size of
a batch as requested by the caller. The batch itself is returned in
the itemsPtr field of the NSFastEnumerationState struct.
To help with returning the objects, the objects array is a C
array preallocated by the caller (on the stack) of size len.
In many cases you can put the objects you want to return in that
objects array, then do itemsPtr = objects. But you
don't have to; if your collection already has the objects to return in
some form of C array, it could return them from there instead.
The state and extra fields of the
NSFastEnumerationState structure allows your collection object
to keep track of the state of the enumeration. In a simple array
implementation, state may keep track of the index of the last
object that was returned, and extra may be unused.
The mutationsPtr field of the NSFastEnumerationState is
used to keep track of mutations. It should point to a number; before
working on each object, the fast enumeration loop will check that this
number has not changed. If it has, a mutation has happened and the
fast enumeration will abort. So, mutationsPtr could be set to
point to some sort of version number of your collection, which is
increased by one every time there is a change (for example when an
object is added or removed). Or, if you are content with less strict
mutation checks, it could point to the number of objects in your
collection or some other value that can be checked to perform an
approximate check that the collection has not been mutated.
Finally, note how we declared the len argument and the return
value to be of type unsigned long. They could also be declared
to be of type unsigned int and everything would still work.
This section is specific for the GNU Objective-C runtime. If you are using a different runtime, you can skip it.
The implementation of messaging in the GNU Objective-C runtime is designed to be portable, and so is based on standard C.
Sending a message in the GNU Objective-C runtime is composed of two
separate steps. First, there is a call to the lookup function,
objc_msg_lookup () (or, in the case of messages to super,
objc_msg_lookup_super ()). This runtime function takes as
argument the receiver and the selector of the method to be called; it
returns the IMP, that is a pointer to the function implementing
the method. The second step of method invocation consists of casting
this pointer function to the appropriate function pointer type, and
calling the function pointed to it with the right arguments.
For example, when the compiler encounters a method invocation such as
[object init], it compiles it into a call to
objc_msg_lookup (object, @selector(init)) followed by a cast
of the returned value to the appropriate function pointer type, and
then it calls it.
If objc_msg_lookup() does not find a suitable method
implementation, because the receiver does not implement the required
method, it tries to see if the class can dynamically register the
method.
To do so, the runtime checks if the class of the receiver implements the method
+ (BOOL) resolveInstanceMethod: (SEL)selector;
in the case of an instance method, or
+ (BOOL) resolveClassMethod: (SEL)selector;
in the case of a class method. If the class implements it, the
runtime invokes it, passing as argument the selector of the original
method, and if it returns YES, the runtime tries the lookup
again, which could now succeed if a matching method was added
dynamically by +resolveInstanceMethod: or
+resolveClassMethod:.
This allows classes to dynamically register methods (by adding them to
the class using class_addMethod) when they are first called.
To do so, a class should implement +resolveInstanceMethod: (or,
depending on the case, +resolveClassMethod:) and have it
recognize the selectors of methods that can be registered dynamically
at runtime, register them, and return YES. It should return
NO for methods that it does not dynamically registered at
runtime.
If +resolveInstanceMethod: (or +resolveClassMethod:) is
not implemented or returns NO, the runtime then tries the
forwarding hook.
Support for +resolveInstanceMethod: and
resolveClassMethod: was added to the GNU Objective-C runtime in
GCC version 4.6.
The GNU Objective-C runtime provides a hook, called
__objc_msg_forward2, which is called by
objc_msg_lookup() when it can't find a method implementation in
the runtime tables and after calling +resolveInstanceMethod:
and +resolveClassMethod: has been attempted and did not succeed
in dynamically registering the method.
To configure the hook, you set the global variable
__objc_msg_foward2 to a function with the same argument and
return types of objc_msg_lookup(). When
objc_msg_lookup() can not find a method implementation, it
invokes the hook function you provided to get a method implementation
to return. So, in practice __objc_msg_forward2 allows you to
extend objc_msg_lookup() by adding some custom code that is
called to do a further lookup when no standard method implementation
can be found using the normal lookup.
This hook is generally reserved for “Foundation” libraries such as
GNUstep Base, which use it to implement their high-level method
forwarding API, typically based around the forwardInvocation:
method. So, unless you are implementing your own “Foundation”
library, you should not set this hook.
In a typical forwarding implementation, the __objc_msg_forward2
hook function determines the argument and return type of the method
that is being looked up, and then creates a function that takes these
arguments and has that return type, and returns it to the caller.
Creating this function is non-trivial and is typically performed using
a dedicated library such as libffi.
The forwarding method implementation thus created is returned by
objc_msg_lookup() and is executed as if it was a normal method
implementation. When the forwarding method implementation is called,
it is usually expected to pack all arguments into some sort of object
(typically, an NSInvocation in a “Foundation” library), and
hand it over to the programmer (forwardInvocation:) who is then
allowed to manipulate the method invocation using a high-level API
provided by the “Foundation” library. For example, the programmer
may want to examine the method invocation arguments and name and
potentially change them before forwarding the method invocation to one
or more local objects (performInvocation:) or even to remote
objects (by using Distributed Objects or some other mechanism). When
all this completes, the return value is passed back and must be
returned correctly to the original caller.
Note that the GNU Objective-C runtime currently provides no support
for method forwarding or method invocations other than the
__objc_msg_forward2 hook.
If the forwarding hook does not exist or returns NULL, the
runtime currently attempts forwarding using an older, deprecated API,
and if that fails, it aborts the program. In future versions of the
GNU Objective-C runtime, the runtime will immediately abort.
Binary compatibility encompasses several related concepts:
The application binary interface implemented by a C or C++ compiler affects code generation and runtime support for:
In addition, the application binary interface implemented by a C++ compiler affects code generation and runtime support for:
Some GCC compilation options cause the compiler to generate code that does not conform to the platform's default ABI. Other options cause different program behavior for implementation-defined features that are not covered by an ABI. These options are provided for consistency with other compilers that do not follow the platform's default ABI or the usual behavior of implementation-defined features for the platform. Be very careful about using such options.
Most platforms have a well-defined ABI that covers C code, but ABIs that cover C++ functionality are not yet common.
Starting with GCC 3.2, GCC binary conventions for C++ are based on a written, vendor-neutral C++ ABI that was designed to be specific to 64-bit Itanium but also includes generic specifications that apply to any platform. This C++ ABI is also implemented by other compiler vendors on some platforms, notably GNU/Linux and BSD systems. We have tried hard to provide a stable ABI that will be compatible with future GCC releases, but it is possible that we will encounter problems that make this difficult. Such problems could include different interpretations of the C++ ABI by different vendors, bugs in the ABI, or bugs in the implementation of the ABI in different compilers. GCC's -Wabi switch warns when G++ generates code that is probably not compatible with the C++ ABI.
The C++ library used with a C++ compiler includes the Standard C++ Library, with functionality defined in the C++ Standard, plus language runtime support. The runtime support is included in a C++ ABI, but there is no formal ABI for the Standard C++ Library. Two implementations of that library are interoperable if one follows the de-facto ABI of the other and if they are both built with the same compiler, or with compilers that conform to the same ABI for C++ compiler and runtime support.
When G++ and another C++ compiler conform to the same C++ ABI, but the implementations of the Standard C++ Library that they normally use do not follow the same ABI for the Standard C++ Library, object files built with those compilers can be used in the same program only if they use the same C++ library. This requires specifying the location of the C++ library header files when invoking the compiler whose usual library is not being used. The location of GCC's C++ header files depends on how the GCC build was configured, but can be seen by using the G++ -v option. With default configuration options for G++ 3.3 the compile line for a different C++ compiler needs to include
-Igcc_install_directory/include/c++/3.3
Similarly, compiling code with G++ that must use a C++ library other than the GNU C++ library requires specifying the location of the header files for that other library.
The most straightforward way to link a program to use a particular C++ library is to use a C++ driver that specifies that C++ library by default. The g++ driver, for example, tells the linker where to find GCC's C++ library (libstdc++) plus the other libraries and startup files it needs, in the proper order.
If a program must use a different C++ library and it's not possible to do the final link using a C++ driver that uses that library by default, it is necessary to tell g++ the location and name of that library. It might also be necessary to specify different startup files and other runtime support libraries, and to suppress the use of GCC's support libraries with one or more of the options -nostdlib, -nostartfiles, and -nodefaultlibs.
gcov is a tool you can use in conjunction with GCC to test code coverage in your programs.
gcov is a test coverage program. Use it in concert with GCC to analyze your programs to help create more efficient, faster running code and to discover untested parts of your program. You can use gcov as a profiling tool to help discover where your optimization efforts will best affect your code. You can also use gcov along with the other profiling tool, gprof, to assess which parts of your code use the greatest amount of computing time.
Profiling tools help you analyze your code's performance. Using a profiler such as gcov or gprof, you can find out some basic performance statistics, such as:
Once you know these things about how your code works when compiled, you can look at each module to see which modules should be optimized. gcov helps you determine where to work on optimization.
Software developers also use coverage testing in concert with testsuites, to make sure software is actually good enough for a release. Testsuites can verify that a program works as expected; a coverage program tests to see how much of the program is exercised by the testsuite. Developers can then determine what kinds of test cases need to be added to the testsuites to create both better testing and a better final product.
You should compile your code without optimization if you plan to use gcov because the optimization, by combining some lines of code into one function, may not give you as much information as you need to look for `hot spots' where the code is using a great deal of computer time. Likewise, because gcov accumulates statistics by line (at the lowest resolution), it works best with a programming style that places only one statement on each line. If you use complicated macros that expand to loops or to other control structures, the statistics are less helpful—they only report on the line where the macro call appears. If your complex macros behave like functions, you can replace them with inline functions to solve this problem.
gcov creates a logfile called sourcefile.gcov which indicates how many times each line of a source file sourcefile.c has executed. You can use these logfiles along with gprof to aid in fine-tuning the performance of your programs. gprof gives timing information you can use along with the information you get from gcov.
gcov works only on code compiled with GCC. It is not compatible with any other profiling or test coverage mechanism.
gcov [options] files
gcov accepts the following options:
-h--help-v--version-a--all-blocks-b--branch-probabilities-c--branch-counts-n--no-output-l--long-file-names-p--preserve-paths-r--relative-only-f--function-summaries-o directory|file--object-directory directory--object-file file-s directory--source-prefix directory-u--unconditional-branches-d--display-progressgcov should be run with the current directory the same as that when you invoked the compiler. Otherwise it will not be able to locate the source files. gcov produces files called mangledname.gcov in the current directory. These contain the coverage information of the source file they correspond to. One .gcov file is produced for each source (or header) file containing code, which was compiled to produce the data files. The mangledname part of the output file name is usually simply the source file name, but can be something more complicated if the ‘-l’ or ‘-p’ options are given. Refer to those options for details.
If you invoke gcov with multiple input files, the contributions from each input file are summed. Typically you would invoke it with the same list of files as the final link of your executable.
The .gcov files contain the ‘:’ separated fields along with program source code. The format is
execution_count:line_number:source line text
Additional block information may succeed each line, when requested by command line option. The execution_count is ‘-’ for lines containing no code. Unexecuted lines are marked ‘#####’ or ‘====’, depending on whether they are reachable by non-exceptional paths or only exceptional paths such as C++ exception handlers, respectively.
Some lines of information at the start have line_number of zero. These preamble lines are of the form
-:0:tag:value
The ordering and number of these preamble lines will be augmented as gcov development progresses — do not rely on them remaining unchanged. Use tag to locate a particular preamble line.
The additional block information is of the form
tag information
The information is human readable, but designed to be simple enough for machine parsing too.
When printing percentages, 0% and 100% are only printed when the values are exactly 0% and 100% respectively. Other values which would conventionally be rounded to 0% or 100% are instead printed as the nearest non-boundary value.
When using gcov, you must first compile your program with two special GCC options: ‘-fprofile-arcs -ftest-coverage’. This tells the compiler to generate additional information needed by gcov (basically a flow graph of the program) and also includes additional code in the object files for generating the extra profiling information needed by gcov. These additional files are placed in the directory where the object file is located.
Running the program will cause profile output to be generated. For each source file compiled with -fprofile-arcs, an accompanying .gcda file will be placed in the object file directory.
Running gcov with your program's source file names as arguments will now produce a listing of the code along with frequency of execution for each line. For example, if your program is called tmp.c, this is what you see when you use the basic gcov facility:
$ gcc -fprofile-arcs -ftest-coverage tmp.c
$ a.out
$ gcov tmp.c
90.00% of 10 source lines executed in file tmp.c
Creating tmp.c.gcov.
The file tmp.c.gcov contains output from gcov. Here is a sample:
-: 0:Source:tmp.c
-: 0:Graph:tmp.gcno
-: 0:Data:tmp.gcda
-: 0:Runs:1
-: 0:Programs:1
-: 1:#include <stdio.h>
-: 2:
-: 3:int main (void)
1: 4:{
1: 5: int i, total;
-: 6:
1: 7: total = 0;
-: 8:
11: 9: for (i = 0; i < 10; i++)
10: 10: total += i;
-: 11:
1: 12: if (total != 45)
#####: 13: printf ("Failure\n");
-: 14: else
1: 15: printf ("Success\n");
1: 16: return 0;
-: 17:}
When you use the -a option, you will get individual block counts, and the output looks like this:
-: 0:Source:tmp.c
-: 0:Graph:tmp.gcno
-: 0:Data:tmp.gcda
-: 0:Runs:1
-: 0:Programs:1
-: 1:#include <stdio.h>
-: 2:
-: 3:int main (void)
1: 4:{
1: 4-block 0
1: 5: int i, total;
-: 6:
1: 7: total = 0;
-: 8:
11: 9: for (i = 0; i < 10; i++)
11: 9-block 0
10: 10: total += i;
10: 10-block 0
-: 11:
1: 12: if (total != 45)
1: 12-block 0
#####: 13: printf ("Failure\n");
$$$$$: 13-block 0
-: 14: else
1: 15: printf ("Success\n");
1: 15-block 0
1: 16: return 0;
1: 16-block 0
-: 17:}
In this mode, each basic block is only shown on one line – the last line of the block. A multi-line block will only contribute to the execution count of that last line, and other lines will not be shown to contain code, unless previous blocks end on those lines. The total execution count of a line is shown and subsequent lines show the execution counts for individual blocks that end on that line. After each block, the branch and call counts of the block will be shown, if the -b option is given.
Because of the way GCC instruments calls, a call count can be shown after a line with no individual blocks. As you can see, line 13 contains a basic block that was not executed.
When you use the -b option, your output looks like this:
$ gcov -b tmp.c
90.00% of 10 source lines executed in file tmp.c
80.00% of 5 branches executed in file tmp.c
80.00% of 5 branches taken at least once in file tmp.c
50.00% of 2 calls executed in file tmp.c
Creating tmp.c.gcov.
Here is a sample of a resulting tmp.c.gcov file:
-: 0:Source:tmp.c
-: 0:Graph:tmp.gcno
-: 0:Data:tmp.gcda
-: 0:Runs:1
-: 0:Programs:1
-: 1:#include <stdio.h>
-: 2:
-: 3:int main (void)
function main called 1 returned 1 blocks executed 75%
1: 4:{
1: 5: int i, total;
-: 6:
1: 7: total = 0;
-: 8:
11: 9: for (i = 0; i < 10; i++)
branch 0 taken 91% (fallthrough)
branch 1 taken 9%
10: 10: total += i;
-: 11:
1: 12: if (total != 45)
branch 0 taken 0% (fallthrough)
branch 1 taken 100%
#####: 13: printf ("Failure\n");
call 0 never executed
-: 14: else
1: 15: printf ("Success\n");
call 0 called 1 returned 100%
1: 16: return 0;
-: 17:}
For each function, a line is printed showing how many times the function is called, how many times it returns and what percentage of the function's blocks were executed.
For each basic block, a line is printed after the last line of the basic block describing the branch or call that ends the basic block. There can be multiple branches and calls listed for a single source line if there are multiple basic blocks that end on that line. In this case, the branches and calls are each given a number. There is no simple way to map these branches and calls back to source constructs. In general, though, the lowest numbered branch or call will correspond to the leftmost construct on the source line.
For a branch, if it was executed at least once, then a percentage indicating the number of times the branch was taken divided by the number of times the branch was executed will be printed. Otherwise, the message “never executed” is printed.
For a call, if it was executed at least once, then a percentage
indicating the number of times the call returned divided by the number
of times the call was executed will be printed. This will usually be
100%, but may be less for functions that call exit or longjmp,
and thus may not return every time they are called.
The execution counts are cumulative. If the example program were executed again without removing the .gcda file, the count for the number of times each line in the source was executed would be added to the results of the previous run(s). This is potentially useful in several ways. For example, it could be used to accumulate data over a number of program runs as part of a test verification suite, or to provide more accurate long-term information over a large number of program runs.
The data in the .gcda files is saved immediately before the program exits. For each source file compiled with -fprofile-arcs, the profiling code first attempts to read in an existing .gcda file; if the file doesn't match the executable (differing number of basic block counts) it will ignore the contents of the file. It then adds in the new execution counts and finally writes the data to the file.
If you plan to use gcov to help optimize your code, you must first compile your program with two special GCC options: ‘-fprofile-arcs -ftest-coverage’. Aside from that, you can use any other GCC options; but if you want to prove that every single line in your program was executed, you should not compile with optimization at the same time. On some machines the optimizer can eliminate some simple code lines by combining them with other lines. For example, code like this:
if (a != b)
c = 1;
else
c = 0;
can be compiled into one instruction on some machines. In this case, there is no way for gcov to calculate separate execution counts for each line because there isn't separate code for each line. Hence the gcov output looks like this if you compiled the program with optimization:
100: 12:if (a != b)
100: 13: c = 1;
100: 14:else
100: 15: c = 0;
The output shows that this block of code, combined by optimization, executed 100 times. In one sense this result is correct, because there was only one instruction representing all four of these lines. However, the output does not indicate how many times the result was 0 and how many times the result was 1.
Inlineable functions can create unexpected line counts. Line counts are shown for the source code of the inlineable function, but what is shown depends on where the function is inlined, or if it is not inlined at all.
If the function is not inlined, the compiler must emit an out of line copy of the function, in any object file that needs it. If fileA.o and fileB.o both contain out of line bodies of a particular inlineable function, they will also both contain coverage counts for that function. When fileA.o and fileB.o are linked together, the linker will, on many systems, select one of those out of line bodies for all calls to that function, and remove or ignore the other. Unfortunately, it will not remove the coverage counters for the unused function body. Hence when instrumented, all but one use of that function will show zero counts.
If the function is inlined in several places, the block structure in each location might not be the same. For instance, a condition might now be calculable at compile time in some instances. Because the coverage of all the uses of the inline function will be shown for the same source lines, the line counts themselves might seem inconsistent.
gcov uses two files for profiling. The names of these files are derived from the original object file by substituting the file suffix with either .gcno, or .gcda. All of these files are placed in the same directory as the object file, and contain data stored in a platform-independent format.
The .gcno file is generated when the source file is compiled with the GCC -ftest-coverage option. It contains information to reconstruct the basic block graphs and assign source line numbers to blocks.
The .gcda file is generated when a program containing object files built with the GCC -fprofile-arcs option is executed. A separate .gcda file is created for each object file compiled with this option. It contains arc transition counts, and some summary information.
The full details of the file format is specified in gcov-io.h, and functions provided in that header file should be used to access the coverage files.
Running the program will cause profile output to be generated. For each source file compiled with -fprofile-arcs, an accompanying .gcda file will be placed in the object file directory. That implicitly requires running the program on the same system as it was built or having the same absolute directory structure on the target system. The program will try to create the needed directory structure, if it is not already present.
To support cross-profiling, a program compiled with -fprofile-arcs can relocate the data files based on two environment variables:
Note: If GCOV_PREFIX_STRIP is set without GCOV_PREFIX is undefined, then a relative path is made out of the hardwired absolute paths.
For example, if the object file /user/build/foo.o was built with -fprofile-arcs, the final executable will try to create the data file /user/build/foo.gcda when running on the target system. This will fail if the corresponding directory does not exist and it is unable to create it. This can be overcome by, for example, setting the environment as ‘GCOV_PREFIX=/target/run’ and ‘GCOV_PREFIX_STRIP=1’. Such a setting will name the data file /target/run/build/foo.gcda.
You must move the data files to the expected directory tree in order to use them for profile directed optimizations (--use-profile), or to use the gcov tool.
This section describes known problems that affect users of GCC. Most of these are not GCC bugs per se—if they were, we would fix them. But the result for a user may be like the result of a bug.
Some of these problems are due to bugs in other software, some are missing features that are too much work to add, and some are places where people's opinions differ as to what is best.
fixincludes script interacts badly with automounters; if the
directory of system header files is automounted, it tends to be
unmounted while fixincludes is running. This would seem to be a
bug in the automounter. We don't know any good way to work around it.
You may run into problems with cross compilation on certain machines, for several reasons.
This section lists various difficulties encountered in using GCC together with other compilers or with the assemblers, linkers, libraries and debuggers on certain systems.
An area where the difference is most apparent is name mangling. The use of different name mangling is intentional, to protect you from more subtle problems. Compilers differ as to many internal details of C++ implementation, including: how class instances are laid out, how multiple inheritance is implemented, and how virtual function calls are handled. If the name encoding were made the same, your programs would link against libraries provided from other compilers—but the programs would then crash when run. Incompatible libraries are then detected at link time, rather than at run time.
double on an 8-byte
boundary, and it expects every double to be so aligned. The Sun
compiler usually gives double values 8-byte alignment, with one
exception: function arguments of type double may not be aligned.
As a result, if a function compiled with Sun CC takes the address of an
argument of type double and passes this pointer of type
double * to a function compiled with GCC, dereferencing the
pointer may cause a fatal signal.
One way to solve this problem is to compile your entire program with GCC.
Another solution is to modify the function that is compiled with
Sun CC to copy the argument into a local variable; local variables
are always properly aligned. A third solution is to modify the function
that uses the pointer to dereference it via the following function
access_double instead of directly with ‘*’:
inline double
access_double (double *unaligned_ptr)
{
union d2i { double d; int i[2]; };
union d2i *p = (union d2i *) unaligned_ptr;
union d2i u;
u.i[0] = p->i[0];
u.i[1] = p->i[1];
return u.d;
}
Storing into the pointer can be done likewise with the same union.
malloc function in the libmalloc.a library
may allocate memory that is only 4 byte aligned. Since GCC on the
SPARC assumes that doubles are 8 byte aligned, this may result in a
fatal signal if doubles are stored in memory allocated by the
libmalloc.a library.
The solution is to not use the libmalloc.a library. Use instead
malloc and related functions from libc.a; they do not have
this problem.
alloca or variable-size arrays. This is because GCC doesn't
generate HP-UX unwind descriptors for such functions. It may even be
impossible to generate them.
(warning) Use of GR3 when
frame >= 8192 may cause conflict.
These warnings are harmless and can be safely ignored.
There are several noteworthy incompatibilities between GNU C and K&R (non-ISO) versions of C.
One consequence is that you cannot call mktemp with a string
constant argument. The function mktemp always alters the
string its argument points to.
Another consequence is that sscanf does not work on some very
old systems when passed a string constant as its format control string
or input. This is because sscanf incorrectly tries to write
into the string constant. Likewise fscanf and scanf.
The solution to these problems is to change the program to use
char-array variables with initialization strings for these
purposes instead of string constants.
-2147483648 is positive.
This is because 2147483648 cannot fit in the type int, so
(following the ISO C rules) its data type is unsigned long int.
Negating this value yields 2147483648 again.
#define foo(a) "a"
will produce output "a" regardless of what the argument a is.
setjmp and longjmp, the only automatic
variables guaranteed to remain valid are those declared
volatile. This is a consequence of automatic register
allocation. Consider this function:
jmp_buf j;
foo ()
{
int a, b;
a = fun1 ();
if (setjmp (j))
return a;
a = fun2 ();
/* longjmp (j) may occur in fun3. */
return a + fun3 ();
}
Here a may or may not be restored to its first value when the
longjmp occurs. If a is allocated in a register, then
its first value is restored; otherwise, it keeps the last value stored
in it.
If you use the -W option with the -O option, you will get a warning when GCC thinks such a problem might be possible.
foobar (
#define luser
hack)
ISO C does not permit such a construct.
In some other C compilers, an extern declaration affects all the
rest of the file even if it happens within a block.
long, etc., with a typedef name,
as shown here:
typedef int foo;
typedef long foo bar;
In ISO C, this is not allowed: long and other type modifiers
require an explicit int.
typedef int foo;
typedef foo foo;
#if 0
You can't expect this to work.
#endif
The best solution to such a problem is to put the text into an actual C comment delimited by ‘/*...*/’.
time, so it did not matter what type your program declared it to
return. But in systems with ISO C headers, time is declared to
return time_t, and if that is not the same as long, then
‘long time ();’ is erroneous.
The solution is to change your program to use appropriate system headers
(<time.h> on systems with ISO C headers) and not to declare
time if the system header files declare it, or failing that to
use time_t as the return type of time.
float, PCC converts it to
a double. GCC actually returns a float. If you are concerned
with PCC compatibility, you should declare your functions to return
double; you might as well say what you mean.
The method used by GCC is as follows: a structure or union which is
1, 2, 4 or 8 bytes long is returned like a scalar. A structure or union
with any other size is stored into an address supplied by the caller
(usually in a special, fixed register, but on some machines it is passed
on the stack). The target hook TARGET_STRUCT_VALUE_RTX
tells GCC where to pass this address.
By contrast, PCC on most target machines returns structures and unions of any size by copying the data into an area of static storage, and then returning the address of that storage as if it were a pointer value. The caller must copy the data from that memory area to the place where the value is wanted. GCC does not use this method because it is slower and nonreentrant.
On some newer machines, PCC uses a reentrant convention for all structure and union returning. GCC on most of these machines uses a compatible convention when returning structures and unions in memory, but still returns small structures and unions in registers.
You can tell GCC to use a compatible convention for all structure and union returning with the option -fpcc-struct-return.
A preprocessing token is a preprocessing number if it begins with a digit and is followed by letters, underscores, digits, periods and ‘e+’, ‘e-’, ‘E+’, ‘E-’, ‘p+’, ‘p-’, ‘P+’, or ‘P-’ character sequences. (In strict C90 mode, the sequences ‘p+’, ‘p-’, ‘P+’ and ‘P-’ cannot appear in preprocessing numbers.)
To make the above program fragment valid, place whitespace in front of the minus sign. This whitespace will end the preprocessing number.
GCC needs to install corrected versions of some system header files. This is because most target systems have some header files that won't work with GCC unless they are changed. Some have bugs, some are incompatible with ISO C, and some depend on special features of other compilers.
Installing GCC automatically creates and installs the fixed header
files, by running a program called fixincludes. Normally, you
don't need to pay attention to this. But there are cases where it
doesn't do the right thing automatically.
The programs that fix the header files do not understand this special way of using symbolic links; therefore, the directory of fixed header files is good only for the machine model used to build it.
It is possible to make separate sets of fixed header files for the different machine models, and arrange a structure of symbolic links so as to use the proper set, but you'll have to do this by hand.
GCC by itself attempts to be a conforming freestanding implementation. See Language Standards Supported by GCC, for details of what this means. Beyond the library facilities required of such an implementation, the rest of the C library is supplied by the vendor of the operating system. If that C library doesn't conform to the C standards, then your programs might get warnings (especially when using -Wall) that you don't expect.
For example, the sprintf function on SunOS 4.1.3 returns
char * while the C standard says that sprintf returns an
int. The fixincludes program could make the prototype for
this function match the Standard, but that would be wrong, since the
function will still return char *.
If you need a Standard compliant library, then you need to find one, as
GCC does not provide one. The GNU C library (called glibc)
provides ISO C, POSIX, BSD, SystemV and X/Open compatibility for
GNU/Linux and HURD-based GNU systems; no recent version of it supports
other systems, though some very old versions did. Version 2.2 of the
GNU C library includes nearly complete C99 support. You could also ask
your operating system vendor if newer libraries are available.
These problems are perhaps regrettable, but we don't know any practical way around them.
This occurs because sometimes GCC optimizes the variable out of existence. There is no way to tell the debugger how to compute the value such a variable “would have had”, and it is not clear that would be desirable anyway. So GCC simply does not mention the eliminated variable when it writes debugging information.
You have to expect a certain amount of disagreement between the executable and your source code, when you use optimization.
int foo (struct mumble *);
struct mumble { ... };
int foo (struct mumble *x)
{ ... }
This code really is erroneous, because the scope of struct
mumble in the prototype is limited to the argument list containing it.
It does not refer to the struct mumble defined with file scope
immediately below—they are two unrelated types with similar names in
different scopes.
But in the definition of foo, the file-scope type is used
because that is available to be inherited. Thus, the definition and
the prototype do not match, and you get an error.
This behavior may seem silly, but it's what the ISO standard specifies.
It is easy enough for you to make your code work by moving the
definition of struct mumble above the prototype. It's not worth
being incompatible with ISO C just to avoid an error for the example
shown above.
If you care about controlling the amount of memory that is accessed, use volatile but do not use bit-fields.
If new system header files are installed, nothing automatically arranges to update the corrected header files. They can be updated using the mkheaders script installed in libexecdir/gcc/target/version/install-tools/.
double in memory.
Compiled code moves values between memory and floating point registers
at its convenience, and moving them into memory truncates them.
You can partially avoid this problem by using the -ffloat-store option (see Optimize Options).
C++ is a complex language and an evolving one, and its standard definition (the ISO C++ standard) was only recently completed. As a result, your C++ compiler may occasionally surprise you, even when its behavior is correct. This section discusses some areas that frequently give rise to questions of this sort.
When a class has static data members, it is not enough to declare the static member; you must also define it. For example:
class Foo
{
...
void method();
static int bar;
};
This declaration only establishes that the class Foo has an
int named Foo::bar, and a member function named
Foo::method. But you still need to define both
method and bar elsewhere. According to the ISO
standard, you must supply an initializer in one (and only one) source
file, such as:
int Foo::bar = 0;
Other C++ compilers may not correctly implement the standard behavior. As a result, when you switch to g++ from one of these compilers, you may discover that a program that appeared to work correctly in fact does not conform to the standard: g++ reports as undefined symbols any static data members that lack definitions.
The C++ standard prescribes that all names that are not dependent on template parameters are bound to their present definitions when parsing a template function or class.5 Only names that are dependent are looked up at the point of instantiation. For example, consider
void foo(double);
struct A {
template <typename T>
void f () {
foo (1); // 1
int i = N; // 2
T t;
t.bar(); // 3
foo (t); // 4
}
static const int N;
};
Here, the names foo and N appear in a context that does
not depend on the type of T. The compiler will thus require that
they are defined in the context of use in the template, not only before
the point of instantiation, and will here use ::foo(double) and
A::N, respectively. In particular, it will convert the integer
value to a double when passing it to ::foo(double).
Conversely, bar and the call to foo in the fourth marked
line are used in contexts that do depend on the type of T, so
they are only looked up at the point of instantiation, and you can
provide declarations for them after declaring the template, but before
instantiating it. In particular, if you instantiate A::f<int>,
the last line will call an overloaded ::foo(int) if one was
provided, even if after the declaration of struct A.
This distinction between lookup of dependent and non-dependent names is called two-stage (or dependent) name lookup. G++ implements it since version 3.4.
Two-stage name lookup sometimes leads to situations with behavior different from non-template codes. The most common is probably this:
template <typename T> struct Base {
int i;
};
template <typename T> struct Derived : public Base<T> {
int get_i() { return i; }
};
In get_i(), i is not used in a dependent context, so the
compiler will look for a name declared at the enclosing namespace scope
(which is the global scope here). It will not look into the base class,
since that is dependent and you may declare specializations of
Base even after declaring Derived, so the compiler can't
really know what i would refer to. If there is no global
variable i, then you will get an error message.
In order to make it clear that you want the member of the base class,
you need to defer lookup until instantiation time, at which the base
class is known. For this, you need to access i in a dependent
context, by either using this->i (remember that this is of
type Derived<T>*, so is obviously dependent), or using
Base<T>::i. Alternatively, Base<T>::i might be brought
into scope by a using-declaration.
Another, similar example involves calling member functions of a base class:
template <typename T> struct Base {
int f();
};
template <typename T> struct Derived : Base<T> {
int g() { return f(); };
};
Again, the call to f() is not dependent on template arguments
(there are no arguments that depend on the type T, and it is also
not otherwise specified that the call should be in a dependent context).
Thus a global declaration of such a function must be available, since
the one in the base class is not visible until instantiation time. The
compiler will consequently produce the following error message:
x.cc: In member function `int Derived<T>::g()':
x.cc:6: error: there are no arguments to `f' that depend on a template
parameter, so a declaration of `f' must be available
x.cc:6: error: (if you use `-fpermissive', G++ will accept your code, but
allowing the use of an undeclared name is deprecated)
To make the code valid either use this->f(), or
Base<T>::f(). Using the -fpermissive flag will also let
the compiler accept the code, by marking all function calls for which no
declaration is visible at the time of definition of the template for
later lookup at instantiation time, as if it were a dependent call.
We do not recommend using -fpermissive to work around invalid
code, and it will also only catch cases where functions in base classes
are called, not where variables in base classes are used (as in the
example above).
Note that some compilers (including G++ versions prior to 3.4) get these examples wrong and accept above code without an error. Those compilers do not implement two-stage name lookup correctly.
It is dangerous to use pointers or references to portions of a
temporary object. The compiler may very well delete the object before
you expect it to, leaving a pointer to garbage. The most common place
where this problem crops up is in classes like string classes,
especially ones that define a conversion function to type char *
or const char *—which is one reason why the standard
string class requires you to call the c_str member
function. However, any class that returns a pointer to some internal
structure is potentially subject to this problem.
For example, a program may use a function strfunc that returns
string objects, and another function charfunc that
operates on pointers to char:
string strfunc ();
void charfunc (const char *);
void
f ()
{
const char *p = strfunc().c_str();
...
charfunc (p);
...
charfunc (p);
}
In this situation, it may seem reasonable to save a pointer to the C
string returned by the c_str member function and use that rather
than call c_str repeatedly. However, the temporary string
created by the call to strfunc is destroyed after p is
initialized, at which point p is left pointing to freed memory.
Code like this may run successfully under some other compilers, particularly obsolete cfront-based compilers that delete temporaries along with normal local variables. However, the GNU C++ behavior is standard-conforming, so if your program depends on late destruction of temporaries it is not portable.
The safe way to write such code is to give the temporary a name, which forces it to remain until the end of the scope of the name. For example:
const string& tmp = strfunc ();
charfunc (tmp.c_str ());
When a base class is virtual, only one subobject of the base class belongs to each full object. Also, the constructors and destructors are invoked only once, and called from the most-derived class. However, such objects behave unspecified when being assigned. For example:
struct Base{
char *name;
Base(char *n) : name(strdup(n)){}
Base& operator= (const Base& other){
free (name);
name = strdup (other.name);
}
};
struct A:virtual Base{
int val;
A():Base("A"){}
};
struct B:virtual Base{
int bval;
B():Base("B"){}
};
struct Derived:public A, public B{
Derived():Base("Derived"){}
};
void func(Derived &d1, Derived &d2)
{
d1 = d2;
}
The C++ standard specifies that ‘Base::Base’ is only called once when constructing or copy-constructing a Derived object. It is unspecified whether ‘Base::operator=’ is called more than once when the implicit copy-assignment for Derived objects is invoked (as it is inside ‘func’ in the example).
G++ implements the “intuitive” algorithm for copy-assignment: assign all
direct bases, then assign all members. In that algorithm, the virtual
base subobject can be encountered more than once. In the example, copying
proceeds in the following order: ‘val’, ‘name’ (via
strdup), ‘bval’, and ‘name’ again.
If application code relies on copy-assignment, a user-defined copy-assignment operator removes any uncertainties. With such an operator, the application can define whether and how the virtual base subobject is assigned.
This section lists changes that people frequently request, but which we do not make because we think GCC is better without them.
Such a feature would work only occasionally—only for calls that appear in the same file as the called function, following the definition. The only way to check all calls reliably is to add a prototype for the function. But adding a prototype eliminates the motivation for this feature. So the feature is not worthwhile.
Shift count operands are probably signed more often than unsigned. Warning about this would cause far more annoyance than good.
Such assignments must be very common; warning about them would cause more annoyance than good.
C contains many standard functions that return a value that most
programs choose to ignore. One obvious example is printf.
Warning about this practice only leads the defensive programmer to
clutter programs with dozens of casts to void. Such casts are
required so frequently that they become visual noise. Writing those
casts becomes so automatic that they no longer convey useful
information about the intentions of the programmer. For functions
where the return value should never be ignored, use the
warn_unused_result function attribute (see Function Attributes).
This would cause storage layout to be incompatible with most other C compilers. And it doesn't seem very important, given that you can get the same result in other ways. The case where it matters most is when the enumeration-valued object is inside a structure, and in that case you can specify a field width explicitly.
The ISO C standard leaves it up to the implementation whether a bit-field
declared plain int is signed or not. This in effect creates two
alternative dialects of C.
The GNU C compiler supports both dialects; you can specify the signed dialect with -fsigned-bitfields and the unsigned dialect with -funsigned-bitfields. However, this leaves open the question of which dialect to use by default.
Currently, the preferred dialect makes plain bit-fields signed, because
this is simplest. Since int is the same as signed int in
every other context, it is cleanest for them to be the same in bit-fields
as well.
Some computer manufacturers have published Application Binary Interface standards which specify that plain bit-fields should be unsigned. It is a mistake, however, to say anything about this issue in an ABI. This is because the handling of plain bit-fields distinguishes two dialects of C. Both dialects are meaningful on every type of machine. Whether a particular object file was compiled using signed bit-fields or unsigned is of no concern to other object files, even if they access the same bit-fields in the same data structures.
A given program is written in one or the other of these two dialects. The program stands a chance to work on most any machine if it is compiled with the proper dialect. It is unlikely to work at all if compiled with the wrong dialect.
Many users appreciate the GNU C compiler because it provides an environment that is uniform across machines. These users would be inconvenienced if the compiler treated plain bit-fields differently on certain machines.
Occasionally users write programs intended only for a particular machine type. On these occasions, the users would benefit if the GNU C compiler were to support by default the same dialect as the other compilers on that machine. But such applications are rare. And users writing a program to run on more than one type of machine cannot possibly benefit from this kind of compatibility.
This is why GCC does and will treat plain bit-fields in the same fashion on all types of machines (by default).
There are some arguments for making bit-fields unsigned by default on all machines. If, for example, this becomes a universal de facto standard, it would make sense for GCC to go along with it. This is something to be considered in the future.
(Of course, users strongly concerned about portability should indicate explicitly in each bit-field whether it is signed or not. In this way, they write programs which have the same meaning in both C dialects.)
__STDC__ when -ansi is not used.
Currently, GCC defines __STDC__ unconditionally. This provides
good results in practice.
Programmers normally use conditionals on __STDC__ to ask whether
it is safe to use certain features of ISO C, such as function
prototypes or ISO token concatenation. Since plain gcc supports
all the features of ISO C, the correct answer to these questions is
“yes”.
Some users try to use __STDC__ to check for the availability of
certain library facilities. This is actually incorrect usage in an ISO
C program, because the ISO C standard says that a conforming
freestanding implementation should define __STDC__ even though it
does not have the library facilities. ‘gcc -ansi -pedantic’ is a
conforming freestanding implementation, and it is therefore required to
define __STDC__, even though it does not come with an ISO C
library.
Sometimes people say that defining __STDC__ in a compiler that
does not completely conform to the ISO C standard somehow violates the
standard. This is illogical. The standard is a standard for compilers
that claim to support ISO C, such as ‘gcc -ansi’—not for other
compilers such as plain gcc. Whatever the ISO C standard says
is relevant to the design of plain gcc without -ansi only
for pragmatic reasons, not as a requirement.
GCC normally defines __STDC__ to be 1, and in addition
defines __STRICT_ANSI__ if you specify the -ansi option,
or a -std option for strict conformance to some version of ISO C.
On some hosts, system include files use a different convention, where
__STDC__ is normally 0, but is 1 if the user specifies strict
conformance to the C Standard. GCC follows the host convention when
processing system include files, but when processing user files it follows
the usual GNU C convention.
__STDC__ in C++.
Programs written to compile with C++-to-C translators get the
value of __STDC__ that goes with the C compiler that is
subsequently used. These programs must test __STDC__
to determine what kind of C preprocessor that compiler uses:
whether they should concatenate tokens in the ISO C fashion
or in the traditional fashion.
These programs work properly with GNU C++ if __STDC__ is defined.
They would not work otherwise.
In addition, many header files are written to provide prototypes in ISO
C but not in traditional C. Many of these header files can work without
change in C++ provided __STDC__ is defined. If __STDC__
is not defined, they will all fail, and will all need to be changed to
test explicitly for C++ as well.
Historically, GCC has not deleted “empty” loops under the assumption that the most likely reason you would put one in a program is to have a delay, so deleting them will not make real programs run any faster.
However, the rationale here is that optimization of a nonempty loop cannot produce an empty one. This held for carefully written C compiled with less powerful optimizers but is not always the case for carefully written C++ or with more powerful optimizers. Thus GCC will remove operations from loops whenever it can determine those operations are not externally visible (apart from the time taken to execute them, of course). In case the loop can be proved to be finite, GCC will also remove the loop itself.
Be aware of this when performing timing tests, for instance the
following loop can be completely removed, provided
some_expression can provably not change any global state.
{
int sum = 0;
int ix;
for (ix = 0; ix != 10000; ix++)
sum += some_expression;
}
Even though sum is accumulated in the loop, no use is made of
that summation, so the accumulation can be removed.
It is never safe to depend on the order of evaluation of side effects. For example, a function call like this may very well behave differently from one compiler to another:
void func (int, int);
int i = 2;
func (i++, i++);
There is no guarantee (in either the C or the C++ standard language
definitions) that the increments will be evaluated in any particular
order. Either increment might happen first. func might get the
arguments ‘2, 3’, or it might get ‘3, 2’, or even ‘2, 2’.
Some ISO C testsuites report failure when the compiler does not produce an error message for a certain program.
ISO C requires a “diagnostic” message for certain kinds of invalid programs, but a warning is defined by GCC to count as a diagnostic. If GCC produces a warning but not an error, that is correct ISO C support. If testsuites call this “failure”, they should be run with the GCC option -pedantic-errors, which will turn these warnings into errors.
The GNU compiler can produce two kinds of diagnostics: errors and warnings. Each kind has a different purpose:
Warnings may indicate danger points where you should check to make sure that your program really does what you intend; or the use of obsolete features; or the use of nonstandard features of GNU C or C++. Many warnings are issued only if you ask for them, with one of the -W options (for instance, -Wall requests a variety of useful warnings).
GCC always tries to compile your program if possible; it never gratuitously rejects a program whose meaning is clear merely because (for instance) it fails to conform to a standard. In some cases, however, the C and C++ standards specify that certain extensions are forbidden, and a diagnostic must be issued by a conforming compiler. The -pedantic option tells GCC to issue warnings in such cases; -pedantic-errors says to make them errors instead. This does not mean that all non-ISO constructs get warnings or errors.
See Options to Request or Suppress Warnings, for more detail on these and related command-line options.
Your bug reports play an essential role in making GCC reliable.
When you encounter a problem, the first thing to do is to see if it is already known. See Trouble. If it isn't known, then you should report the problem.
If you are not sure whether you have found a bug, here are some guidelines:
asm statement), that is a compiler bug, unless the
compiler reports errors (not just warnings) which would ordinarily
prevent the assembler from being run.
However, you must double-check to make sure, because you may have a program whose behavior is undefined, which happened by chance to give the desired results with another C or C++ compiler.
For example, in many nonoptimizing compilers, you can write ‘x;’
at the end of a function instead of ‘return x;’, with the same
results. But the value of the function is undefined if return
is omitted; it is not a bug when GCC produces different results.
Problems often result from expressions with two increment operators,
as in f (*p++, *p++). Your previous compiler might have
interpreted that expression the way you intended; GCC might
interpret it another way. Neither compiler is wrong. The bug is
in your code.
After you have localized the error to a single source line, it should be easy to check for these things. If your program is correct and well defined, you have found a compiler bug.
Bugs should be reported to the bug database at http://bugs.debian.org/.
If you need help installing, using or changing GCC, there are two ways to find it:
For further information, see http://gcc.gnu.org/faq.html#support.
If you would like to help pretest GCC releases to assure they work well, current development sources are available by SVN (see http://gcc.gnu.org/svn.html). Source and binary snapshots are also available for FTP; see http://gcc.gnu.org/snapshots.html.
If you would like to work on improvements to GCC, please read the advice at these URLs:
http://gcc.gnu.org/contribute.html
http://gcc.gnu.org/contributewhy.html
for information on how to make useful contributions and avoid duplication of effort. Suggested projects are listed at http://gcc.gnu.org/projects/.
If you want to have more free software a few years from now, it makes sense for you to help encourage people to contribute funds for its development. The most effective approach known is to encourage commercial redistributors to donate.
Users of free software systems can boost the pace of development by encouraging for-a-fee distributors to donate part of their selling price to free software developers—the Free Software Foundation, and others.
The way to convince distributors to do this is to demand it and expect it from them. So when you compare distributors, judge them partly by how much they give to free software development. Show distributors they must compete to be the one who gives the most.
To make this approach work, you must insist on numbers that you can compare, such as, “We will donate ten dollars to the Frobnitz project for each disk sold.” Don't be satisfied with a vague promise, such as “A portion of the profits are donated,” since it doesn't give a basis for comparison.
Even a precise fraction “of the profits from this disk” is not very meaningful, since creative accounting and unrelated business decisions can greatly alter what fraction of the sales price counts as profit. If the price you pay is $50, ten percent of the profit is probably less than a dollar; it might be a few cents, or nothing at all.
Some redistributors do development work themselves. This is useful too; but to keep everyone honest, you need to inquire how much they do, and what kind. Some kinds of development make much more long-term difference than others. For example, maintaining a separate version of a program contributes very little; maintaining the standard version of a program for the whole community contributes much. Easy new ports contribute little, since someone else would surely do them; difficult ports such as adding a new CPU to the GNU Compiler Collection contribute more; major new features or packages contribute the most.
By establishing the idea that supporting further development is “the proper thing to do” when distributing free software for a fee, we can assure a steady flow of resources into making more free software.
Copyright © 1994 Free Software Foundation, Inc.
Verbatim copying and redistribution of this section is permitted
without royalty; alteration is not permitted.
The GNU Project was launched in 1984 to develop a complete Unix-like operating system which is free software: the GNU system. (GNU is a recursive acronym for “GNU's Not Unix”; it is pronounced “guh-NEW”.) Variants of the GNU operating system, which use the kernel Linux, are now widely used; though these systems are often referred to as “Linux”, they are more accurately called GNU/Linux systems.
For more information, see:
http://www.gnu.org/
http://www.gnu.org/gnu/linux-and-gnu.html
Copyright © 2007 Free Software Foundation, Inc. http://fsf.org/
Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.
The GNU General Public License is a free, copyleft license for software and other kinds of works.
The licenses for most software and other practical works are designed to take away your freedom to share and change the works. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change all versions of a program–to make sure it remains free software for all its users. We, the Free Software Foundation, use the GNU General Public License for most of our software; it applies also to any other work released this way by its authors. You can apply it to your programs, too.
When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for them if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs, and that you know you can do these things.
To protect your rights, we need to prevent others from denying you these rights or asking you to surrender the rights. Therefore, you have certain responsibilities if you distribute copies of the software, or if you modify it: responsibilities to respect the freedom of others.
For example, if you distribute copies of such a program, whether gratis or for a fee, you must pass on to the recipients the same freedoms that you received. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights.
Developers that use the GNU GPL protect your rights with two steps: (1) assert copyright on the software, and (2) offer you this License giving you legal permission to copy, distribute and/or modify it.
For the developers' and authors' protection, the GPL clearly explains that there is no warranty for this free software. For both users' and authors' sake, the GPL requires that modified versions be marked as changed, so that their problems will not be attributed erroneously to authors of previous versions.
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All rights granted under this License are granted for the term of copyright on the Program, and are irrevocable provided the stated conditions are met. This License explicitly affirms your unlimited permission to run the unmodified Program. The output from running a covered work is covered by this License only if the output, given its content, constitutes a covered work. This License acknowledges your rights of fair use or other equivalent, as provided by copyright law.
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You may convey verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice; keep intact all notices stating that this License and any non-permissive terms added in accord with section 7 apply to the code; keep intact all notices of the absence of any warranty; and give all recipients a copy of this License along with the Program.
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“Additional permissions” are terms that supplement the terms of this License by making exceptions from one or more of its conditions. Additional permissions that are applicable to the entire Program shall be treated as though they were included in this License, to the extent that they are valid under applicable law. If additional permissions apply only to part of the Program, that part may be used separately under those permissions, but the entire Program remains governed by this License without regard to the additional permissions.
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You are not required to accept this License in order to receive or run a copy of the Program. Ancillary propagation of a covered work occurring solely as a consequence of using peer-to-peer transmission to receive a copy likewise does not require acceptance. However, nothing other than this License grants you permission to propagate or modify any covered work. These actions infringe copyright if you do not accept this License. Therefore, by modifying or propagating a covered work, you indicate your acceptance of this License to do so.
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You may not impose any further restrictions on the exercise of the rights granted or affirmed under this License. For example, you may not impose a license fee, royalty, or other charge for exercise of rights granted under this License, and you may not initiate litigation (including a cross-claim or counterclaim in a lawsuit) alleging that any patent claim is infringed by making, using, selling, offering for sale, or importing the Program or any portion of it.
A “contributor” is a copyright holder who authorizes use under this License of the Program or a work on which the Program is based. The work thus licensed is called the contributor's “contributor version”.
A contributor's “essential patent claims” are all patent claims owned or controlled by the contributor, whether already acquired or hereafter acquired, that would be infringed by some manner, permitted by this License, of making, using, or selling its contributor version, but do not include claims that would be infringed only as a consequence of further modification of the contributor version. For purposes of this definition, “control” includes the right to grant patent sublicenses in a manner consistent with the requirements of this License.
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If you convey a covered work, knowingly relying on a patent license, and the Corresponding Source of the work is not available for anyone to copy, free of charge and under the terms of this License, through a publicly available network server or other readily accessible means, then you must either (1) cause the Corresponding Source to be so available, or (2) arrange to deprive yourself of the benefit of the patent license for this particular work, or (3) arrange, in a manner consistent with the requirements of this License, to extend the patent license to downstream recipients. “Knowingly relying” means you have actual knowledge that, but for the patent license, your conveying the covered work in a country, or your recipient's use of the covered work in a country, would infringe one or more identifiable patents in that country that you have reason to believe are valid.
If, pursuant to or in connection with a single transaction or arrangement, you convey, or propagate by procuring conveyance of, a covered work, and grant a patent license to some of the parties receiving the covered work authorizing them to use, propagate, modify or convey a specific copy of the covered work, then the patent license you grant is automatically extended to all recipients of the covered work and works based on it.
A patent license is “discriminatory” if it does not include within the scope of its coverage, prohibits the exercise of, or is conditioned on the non-exercise of one or more of the rights that are specifically granted under this License. You may not convey a covered work if you are a party to an arrangement with a third party that is in the business of distributing software, under which you make payment to the third party based on the extent of your activity of conveying the work, and under which the third party grants, to any of the parties who would receive the covered work from you, a discriminatory patent license (a) in connection with copies of the covered work conveyed by you (or copies made from those copies), or (b) primarily for and in connection with specific products or compilations that contain the covered work, unless you entered into that arrangement, or that patent license was granted, prior to 28 March 2007.
Nothing in this License shall be construed as excluding or limiting any implied license or other defenses to infringement that may otherwise be available to you under applicable patent law.
If conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot convey a covered work so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not convey it at all. For example, if you agree to terms that obligate you to collect a royalty for further conveying from those to whom you convey the Program, the only way you could satisfy both those terms and this License would be to refrain entirely from conveying the Program.
Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU Affero General Public License into a single combined work, and to convey the resulting work. The terms of this License will continue to apply to the part which is the covered work, but the special requirements of the GNU Affero General Public License, section 13, concerning interaction through a network will apply to the combination as such.
The Free Software Foundation may publish revised and/or new versions of the GNU General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.
Each version is given a distinguishing version number. If the Program specifies that a certain numbered version of the GNU General Public License “or any later version” applies to it, you have the option of following the terms and conditions either of that numbered version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of the GNU General Public License, you may choose any version ever published by the Free Software Foundation.
If the Program specifies that a proxy can decide which future versions of the GNU General Public License can be used, that proxy's public statement of acceptance of a version permanently authorizes you to choose that version for the Program.
Later license versions may give you additional or different permissions. However, no additional obligations are imposed on any author or copyright holder as a result of your choosing to follow a later version.
THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
If the disclaimer of warranty and limitation of liability provided above cannot be given local legal effect according to their terms, reviewing courts shall apply local law that most closely approximates an absolute waiver of all civil liability in connection with the Program, unless a warranty or assumption of liability accompanies a copy of the Program in return for a fee.
If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.
one line to give the program's name and a brief idea of what it does.
Copyright (C) year name of author
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see http://www.gnu.org/licenses/.
Also add information on how to contact you by electronic and paper mail.
If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode:
program Copyright (C) year name of author
This program comes with ABSOLUTELY NO WARRANTY; for details type ‘show w’.
This is free software, and you are welcome to redistribute it
under certain conditions; type ‘show c’ for details.
The hypothetical commands ‘show w’ and ‘show c’ should show the appropriate parts of the General Public License. Of course, your program's commands might be different; for a GUI interface, you would use an “about box”.
You should also get your employer (if you work as a programmer) or school, if any, to sign a “copyright disclaimer” for the program, if necessary. For more information on this, and how to apply and follow the GNU GPL, see http://www.gnu.org/licenses/.
The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read http://www.gnu.org/philosophy/why-not-lgpl.html.
Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
http://fsf.org/
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
The purpose of this License is to make a manual, textbook, or other functional and useful document free in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.
This License is a kind of “copyleft”, which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.
We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.
This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein. The “Document”, below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as “you”. You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law.
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The “Invariant Sections” are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document may contain zero Invariant Sections. If the Document does not identify any Invariant Sections then there are none.
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A “Transparent” copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, that is suitable for revising the document straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent modification by readers is not Transparent. An image format is not Transparent if used for any substantial amount of text. A copy that is not “Transparent” is called “Opaque”.
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The “Title Page” means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, “Title Page” means the text near the most prominent appearance of the work's title, preceding the beginning of the body of the text.
The “publisher” means any person or entity that distributes copies of the Document to the public.
A section “Entitled XYZ” means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a specific section name mentioned below, such as “Acknowledgements”, “Dedications”, “Endorsements”, or “History”.) To “Preserve the Title” of such a section when you modify the Document means that it remains a section “Entitled XYZ” according to this definition.
The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document. These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License.
You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3.
You may also lend copies, under the same conditions stated above, and you may publicly display copies.
If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document's license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects.
If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages.
If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using public-standard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public.
It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.
You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:
If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version's license notice. These titles must be distinct from any other section titles.
You may add a section Entitled “Endorsements”, provided it contains nothing but endorsements of your Modified Version by various parties—for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard.
You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one.
The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version.
You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers.
The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work.
In the combination, you must combine any sections Entitled “History” in the various original documents, forming one section Entitled “History”; likewise combine any sections Entitled “Acknowledgements”, and any sections Entitled “Dedications”. You must delete all sections Entitled “Endorsements.”
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If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.
The GCC project would like to thank its many contributors. Without them the project would not have been nearly as successful as it has been. Any omissions in this list are accidental. Feel free to contact law@redhat.com or gerald@pfeifer.com if you have been left out or some of your contributions are not listed. Please keep this list in alphabetical order.
valarray<>, complex<>, maintaining the numerics library
(including that pesky <limits> :-) and keeping up-to-date anything
to do with numbers.
complex<>, sanity checking and disbursement, configuration
architecture, libio maintenance, and early math work.
restrict support, and serving as release manager for GCC 3.x.
INTEGER*1, INTEGER*2, and
LOGICAL*1.
The following people are recognized for their contributions to GNAT, the Ada front end of GCC:
The following people are recognized for their contributions of new features, bug reports, testing and integration of classpath/libgcj for GCC version 4.1:
JTree implementation and lots Free Swing
additions and bug fixes.
GapContent bug fixes.
JList, Free Swing 1.5 updates and mouse event
fixes, lots of Free Swing work including JTable editing.
HTTPURLConnection fixes.
MessageFormat fixes.
Serialization fixes.
StAX
and DOM xml:id support.
TreePath and TreeSelection fixes.
URLClassLoader updates.
SocketTimeoutException.
BitSet bug fixes, HttpURLConnection
rewrite and improvements.
ClassLoader and nio cleanups, serialization fixes,
better Proxy support, bug fixes and IKVM integration.
AccessControlContext fixes.
VMClassLoader and AccessController
improvements.
basic and metal icon and plaf support
and lots of documenting, Lots of Free Swing and metal theme
additions. MetalIconFactory implementation.
MIDI framework, ALSA and DSSI
providers.
Serialization and URLClassLoader fixes,
gcj build speedups.
JFileChooser implementation.
Locale and net fixes, URI RFC2986
updates, Serialization fixes, Properties XML support and
generic branch work, VMIntegration guide update.
TimeZone bug fixing.
NetworkInterface implementation and updates.
BoxLayout, GrayFilter and
SplitPane, plus bug fixes all over. Lots of Free Swing work
including styled text.
String cleanups and optimization suggestions.
Locale updates, bug and
build fixes.
Pointer updates. Logger bug fixes.
Graphics2D upgraded to Cairo 0.5 and new regex
features.
TextLayout
fixes. GtkImage rewrite, 2D, awt, free swing and date/time fixes and
implementing the Qt4 peers.
FileChannel lock,
SystemLogger and FileHandler rotate implementations, NIO
FileChannel.map support, security and policy updates.
File locking fixes.
Image, Logger and URLClassLoader
updates.
MenuSelectionManager implementation.
BasicTreeUI and JTree fixes.
TreeNode enumerations and ActionCommand and various
fixes, XML and URL, AWT and Free Swing bug fixes.
CACAO integration, fdlibm updates.
VMClassLoader boot packages support suggestions.
Qt4
support for Darwin/OS X, Graphics2D support, gtk+
updates.
DEBUG support, build cleanups and
Kaffe integration. Qt4 build infrastructure, SHA1PRNG
and GdkPixbugDecoder updates.
Clipboard implementation, system call interrupts and network
timeouts and GdkPixpufDecoder fixes.
In addition to the above, all of which also contributed time and energy in testing GCC, we would like to thank the following for their contributions to testing:
And finally we'd like to thank everyone who uses the compiler, provides feedback and generally reminds us why we're doing this work in the first place.
GCC's command line options are indexed here without any initial ‘-’ or ‘--’. Where an option has both positive and negative forms (such as -foption and -fno-option), relevant entries in the manual are indexed under the most appropriate form; it may sometimes be useful to look up both forms.
###: Overall Options-fno-keep-inline-dllexport: Optimize Options-mcpu: RX Options8bit-idiv: i386 and x86-64 OptionsA: Preprocessor Optionsall_load: Darwin Optionsallowable_client: Darwin Optionsansi: Non-bugsansi: Other Builtinsansi: Preprocessor Optionsansi: C Dialect Optionsansi: Standardsarch_errors_fatal: Darwin Optionsaux-info: C Dialect Optionsavx256-split-unaligned-load: i386 and x86-64 Optionsavx256-split-unaligned-store: i386 and x86-64 OptionsB: Directory OptionsBdynamic: VxWorks Optionsbind_at_load: Darwin OptionsBstatic: VxWorks Optionsbundle: Darwin Optionsbundle_loader: Darwin Optionsc: Link OptionsC: Preprocessor Optionsc: Overall Optionsclient_name: Darwin Optionscompatibility_version: Darwin Optionscoverage: Debugging Optionscurrent_version: Darwin OptionsD: Preprocessor Optionsd: Debugging OptionsdA: Debugging Optionsda: Debugging OptionsdD: Preprocessor OptionsdD: Debugging Optionsdead_strip: Darwin Optionsdependency-file: Darwin OptionsdH: Debugging OptionsdI: Preprocessor OptionsdM: Preprocessor OptionsdN: Preprocessor OptionsdP: Debugging Optionsdp: Debugging OptionsdU: Preprocessor Optionsdumpmachine: Debugging Optionsdumpspecs: Debugging Optionsdumpversion: Debugging Optionsdv: Debugging Optionsdx: Debugging Optionsdylib_file: Darwin Optionsdylinker_install_name: Darwin Optionsdynamic: Darwin Optionsdynamiclib: Darwin OptionsE: Link OptionsE: Overall OptionsEB: MIPS OptionsEL: MIPS Optionsexported_symbols_list: Darwin OptionsF: Darwin Optionsfabi-version: C++ Dialect Optionsfalign-functions: Optimize Optionsfalign-jumps: Optimize Optionsfalign-labels: Optimize Optionsfalign-loops: Optimize Optionsfassociative-math: Optimize Optionsfasynchronous-unwind-tables: Code Gen Optionsfauto-inc-dec: Optimize Optionsfbounds-check: Code Gen Optionsfbranch-probabilities: Optimize Optionsfbranch-target-load-optimize: Optimize Optionsfbranch-target-load-optimize2: Optimize Optionsfbtr-bb-exclusive: Optimize Optionsfcall-saved: Code Gen Optionsfcall-used: Code Gen Optionsfcaller-saves: Optimize Optionsfcheck-data-deps: Optimize Optionsfcheck-new: C++ Dialect Optionsfcombine-stack-adjustments: Optimize Optionsfcommon: Variable Attributesfcompare-debug: Debugging Optionsfcompare-debug-second: Debugging Optionsfcompare-elim: Optimize Optionsfcond-mismatch: C Dialect Optionsfconserve-space: C++ Dialect Optionsfconserve-stack: Optimize Optionsfconstant-string-class: Objective-C and Objective-C++ Dialect Optionsfconstexpr-depth: C++ Dialect Optionsfcprop-registers: Optimize Optionsfcrossjumping: Optimize Optionsfcse-follow-jumps: Optimize Optionsfcse-skip-blocks: Optimize Optionsfcx-fortran-rules: Optimize Optionsfcx-limited-range: Optimize Optionsfdata-sections: Optimize Optionsfdbg-cnt: Debugging Optionsfdbg-cnt-list: Debugging Optionsfdce: Optimize Optionsfdebug-cpp: Preprocessor Optionsfdebug-prefix-map: Debugging Optionsfdebug-types-section: Debugging Optionsfdeduce-init-list: C++ Dialect Optionsfdelayed-branch: Optimize Optionsfdelete-null-pointer-checks: Optimize Optionsfdevirtualize: Optimize Optionsfdiagnostics-show-location: Language Independent Optionsfdiagnostics-show-option: Language Independent Optionsfdirectives-only: Preprocessor Optionsfdisable-: Debugging Optionsfdollars-in-identifiers: Interoperationfdollars-in-identifiers: Preprocessor Optionsfdse: Optimize Optionsfdump-class-hierarchy: Debugging Optionsfdump-final-insns: Debugging Optionsfdump-ipa: Debugging Optionsfdump-noaddr: Debugging Optionsfdump-passes: Debugging Optionsfdump-rtl-alignments: Debugging Optionsfdump-rtl-all: Debugging Optionsfdump-rtl-asmcons: Debugging Optionsfdump-rtl-auto_inc_dec: Debugging Optionsfdump-rtl-barriers: Debugging Optionsfdump-rtl-bbpart: Debugging Optionsfdump-rtl-bbro: Debugging Optionsfdump-rtl-btl2: Debugging Optionsfdump-rtl-bypass: Debugging Optionsfdump-rtl-ce1: Debugging Optionsfdump-rtl-ce2: Debugging Optionsfdump-rtl-ce3: Debugging Optionsfdump-rtl-combine: Debugging Optionsfdump-rtl-compgotos: Debugging Optionsfdump-rtl-cprop_hardreg: Debugging Optionsfdump-rtl-csa: Debugging Optionsfdump-rtl-cse1: Debugging Optionsfdump-rtl-cse2: Debugging Optionsfdump-rtl-dbr: Debugging Optionsfdump-rtl-dce: Debugging Optionsfdump-rtl-dce1: Debugging Optionsfdump-rtl-dce2: Debugging Optionsfdump-rtl-dfinish: Debugging Optionsfdump-rtl-dfinit: Debugging Optionsfdump-rtl-eh: Debugging Optionsfdump-rtl-eh_ranges: Debugging Optionsfdump-rtl-expand: Debugging Optionsfdump-rtl-fwprop1: Debugging Optionsfdump-rtl-fwprop2: Debugging Optionsfdump-rtl-gcse1: Debugging Optionsfdump-rtl-gcse2: Debugging Optionsfdump-rtl-init-regs: Debugging Optionsfdump-rtl-initvals: Debugging Optionsfdump-rtl-into_cfglayout: Debugging Optionsfdump-rtl-ira: Debugging Optionsfdump-rtl-jump: Debugging Optionsfdump-rtl-loop2: Debugging Optionsfdump-rtl-mach: Debugging Optionsfdump-rtl-mode_sw: Debugging Optionsfdump-rtl-outof_cfglayout: Debugging Optionsfdump-rtl-peephole2: Debugging Optionsfdump-rtl-postreload: Debugging Optionsfdump-rtl-pro_and_epilogue: Debugging Optionsfdump-rtl-regclass: Debugging Optionsfdump-rtl-regmove: Debugging Optionsfdump-rtl-rnreg: Debugging Optionsfdump-rtl-sched1: Debugging Optionsfdump-rtl-sched2: Debugging Optionsfdump-rtl-see: Debugging Optionsfdump-rtl-seqabstr: Debugging Optionsfdump-rtl-shorten: Debugging Optionsfdump-rtl-sibling: Debugging Optionsfdump-rtl-sms: Debugging Optionsfdump-rtl-split1: Debugging Optionsfdump-rtl-split2: Debugging Optionsfdump-rtl-split3: Debugging Optionsfdump-rtl-split4: Debugging Optionsfdump-rtl-split5: Debugging Optionsfdump-rtl-stack: Debugging Optionsfdump-rtl-subreg1: Debugging Optionsfdump-rtl-subreg2: Debugging Optionsfdump-rtl-subregs_of_mode_finish: Debugging Optionsfdump-rtl-subregs_of_mode_init: Debugging Optionsfdump-rtl-unshare: Debugging Optionsfdump-rtl-vartrack: Debugging Optionsfdump-rtl-vregs: Debugging Optionsfdump-rtl-web: Debugging Optionsfdump-statistics: Debugging Optionsfdump-translation-unit: Debugging Optionsfdump-tree: Debugging Optionsfdump-tree-alias: Debugging Optionsfdump-tree-all: Debugging Optionsfdump-tree-ccp: Debugging Optionsfdump-tree-cfg: Debugging Optionsfdump-tree-ch: Debugging Optionsfdump-tree-copyprop: Debugging Optionsfdump-tree-copyrename: Debugging Optionsfdump-tree-dce: Debugging Optionsfdump-tree-dom: Debugging Optionsfdump-tree-dse: Debugging Optionsfdump-tree-forwprop: Debugging Optionsfdump-tree-fre: Debugging Optionsfdump-tree-gimple: Debugging Optionsfdump-tree-mudflap: Debugging Optionsfdump-tree-nrv: Debugging Optionsfdump-tree-optimized: Debugging Optionsfdump-tree-original: Debugging Optionsfdump-tree-phiopt: Debugging Optionsfdump-tree-pre: Debugging Optionsfdump-tree-sink: Debugging Optionsfdump-tree-slp: Debugging Optionsfdump-tree-sra: Debugging Optionsfdump-tree-ssa: Debugging Optionsfdump-tree-store_copyprop: Debugging Optionsfdump-tree-storeccp: Debugging Optionsfdump-tree-vcg: Debugging Optionsfdump-tree-vect: Debugging Optionsfdump-tree-vrp: Debugging Optionsfdump-unnumbered: Debugging Optionsfdump-unnumbered-links: Debugging Optionsfdwarf2-cfi-asm: Debugging Optionsfearly-inlining: Optimize Optionsfeliminate-dwarf2-dups: Debugging Optionsfeliminate-unused-debug-symbols: Debugging Optionsfeliminate-unused-debug-types: Debugging Optionsfenable-: Debugging Optionsfexceptions: Code Gen Optionsfexcess-precision: Optimize Optionsfexec-charset: Preprocessor Optionsfexpensive-optimizations: Optimize Optionsfextended-identifiers: Preprocessor Optionsffast-math: Optimize Optionsffat-lto-objects: Optimize Optionsffinite-math-only: Optimize Optionsffix-and-continue: Darwin Optionsffixed: Code Gen Optionsffloat-store: Disappointmentsffloat-store: Optimize Optionsffor-scope: C++ Dialect Optionsfforward-propagate: Optimize Optionsffp-contract: Optimize Optionsffreestanding: Function Attributesffreestanding: Warning Optionsffreestanding: C Dialect Optionsffreestanding: Standardsffriend-injection: C++ Dialect Optionsffunction-sections: Optimize Optionsfgcse: Optimize Optionsfgcse-after-reload: Optimize Optionsfgcse-las: Optimize Optionsfgcse-lm: Optimize Optionsfgcse-sm: Optimize Optionsfgnu-runtime: Objective-C and Objective-C++ Dialect Optionsfgnu-tm: C Dialect Optionsfgnu89-inline: C Dialect Optionsfgraphite-identity: Optimize Optionsfhosted: C Dialect Optionsfif-conversion: Optimize Optionsfif-conversion2: Optimize Optionsfilelist: Darwin Optionsfindirect-data: Darwin Optionsfindirect-inlining: Optimize Optionsfinhibit-size-directive: Code Gen Optionsfinline-functions: Optimize Optionsfinline-functions-called-once: Optimize Optionsfinline-limit: Optimize Optionsfinline-small-functions: Optimize Optionsfinput-charset: Preprocessor Optionsfinstrument-functions: Function Attributesfinstrument-functions: Code Gen Optionsfinstrument-functions-exclude-file-list: Code Gen Optionsfinstrument-functions-exclude-function-list: Code Gen Optionsfipa-cp: Optimize Optionsfipa-cp-clone: Optimize Optionsfipa-matrix-reorg: Optimize Optionsfipa-profile: Optimize Optionsfipa-pta: Optimize Optionsfipa-pure-const: Optimize Optionsfipa-reference: Optimize Optionsfipa-sra: Optimize Optionsfira-loop-pressure: Optimize Optionsfira-verbose: Optimize Optionsfivopts: Optimize Optionsfkeep-inline-functions: Inlinefkeep-inline-functions: Optimize Optionsfkeep-static-consts: Optimize Optionsflat_namespace: Darwin Optionsflax-vector-conversions: C Dialect Optionsfleading-underscore: Code Gen Optionsfloop-block: Optimize Optionsfloop-flatten: Optimize Optionsfloop-interchange: Optimize Optionsfloop-parallelize-all: Optimize Optionsfloop-strip-mine: Optimize Optionsflto: Optimize Optionsflto-partition: Optimize Optionsfmax-errors: Warning Optionsfmem-report: Debugging Optionsfmerge-all-constants: Optimize Optionsfmerge-constants: Optimize Optionsfmerge-debug-strings: Debugging Optionsfmessage-length: Language Independent Optionsfmodulo-sched: Optimize Optionsfmodulo-sched-allow-regmoves: Optimize Optionsfmove-loop-invariants: Optimize Optionsfms-extensions: Unnamed Fieldsfms-extensions: C++ Dialect Optionsfms-extensions: C Dialect Optionsfmudflap: Optimize Optionsfmudflapir: Optimize Optionsfmudflapth: Optimize Optionsfnext-runtime: Objective-C and Objective-C++ Dialect Optionsfno-access-control: C++ Dialect Optionsfno-asm: C Dialect Optionsfno-branch-count-reg: Optimize Optionsfno-builtin: Other Builtinsfno-builtin: Function Attributesfno-builtin: Warning Optionsfno-builtin: C Dialect Optionsfno-common: Variable Attributesfno-common: Code Gen Optionsfno-compare-debug: Debugging Optionsfno-debug-types-section: Debugging Optionsfno-default-inline: Inlinefno-default-inline: Optimize Optionsfno-default-inline: C++ Dialect Optionsfno-defer-pop: Optimize Optionsfno-diagnostics-show-option: Language Independent Optionsfno-dwarf2-cfi-asm: Debugging Optionsfno-elide-constructors: C++ Dialect Optionsfno-enforce-eh-specs: C++ Dialect Optionsfno-for-scope: C++ Dialect Optionsfno-function-cse: Optimize Optionsfno-gnu-keywords: C++ Dialect Optionsfno-guess-branch-probability: Optimize Optionsfno-ident: Code Gen Optionsfno-implement-inlines: C++ Interfacefno-implement-inlines: C++ Dialect Optionsfno-implicit-inline-templates: C++ Dialect Optionsfno-implicit-templates: Template Instantiationfno-implicit-templates: C++ Dialect Optionsfno-inline: Optimize Optionsfno-ira-share-save-slots: Optimize Optionsfno-ira-share-spill-slots: Optimize Optionsfno-jump-tables: Code Gen Optionsfno-math-errno: Optimize Optionsfno-merge-debug-strings: Debugging Optionsfno-nil-receivers: Objective-C and Objective-C++ Dialect Optionsfno-nonansi-builtins: C++ Dialect Optionsfno-operator-names: C++ Dialect Optionsfno-optional-diags: C++ Dialect Optionsfno-peephole: Optimize Optionsfno-peephole2: Optimize Optionsfno-pretty-templates: C++ Dialect Optionsfno-rtti: C++ Dialect Optionsfno-sched-interblock: Optimize Optionsfno-sched-spec: Optimize Optionsfno-set-stack-executable: i386 and x86-64 Windows Optionsfno-show-column: Preprocessor Optionsfno-signed-bitfields: C Dialect Optionsfno-signed-zeros: Optimize Optionsfno-stack-limit: Code Gen Optionsfno-threadsafe-statics: C++ Dialect Optionsfno-toplevel-reorder: Optimize Optionsfno-trapping-math: Optimize Optionsfno-unsigned-bitfields: C Dialect Optionsfno-use-cxa-get-exception-ptr: C++ Dialect Optionsfno-var-tracking-assignments: Debugging Optionsfno-var-tracking-assignments-toggle: Debugging Optionsfno-weak: C++ Dialect Optionsfno-working-directory: Preprocessor Optionsfno-zero-initialized-in-bss: Optimize Optionsfnon-call-exceptions: Code Gen Optionsfnothrow-opt: C++ Dialect Optionsfobjc-abi-version: Objective-C and Objective-C++ Dialect Optionsfobjc-call-cxx-cdtors: Objective-C and Objective-C++ Dialect Optionsfobjc-direct-dispatch: Objective-C and Objective-C++ Dialect Optionsfobjc-exceptions: Objective-C and Objective-C++ Dialect Optionsfobjc-gc: Objective-C and Objective-C++ Dialect Optionsfobjc-nilcheck: Objective-C and Objective-C++ Dialect Optionsfobjc-std: Objective-C and Objective-C++ Dialect Optionsfomit-frame-pointer: Optimize Optionsfopenmp: C Dialect Optionsfoptimize-register-move: Optimize Optionsfoptimize-sibling-calls: Optimize Optionsforce_cpusubtype_ALL: Darwin Optionsforce_flat_namespace: Darwin Optionsfpack-struct: Code Gen Optionsfpartial-inlining: Optimize Optionsfpcc-struct-return: Incompatibilitiesfpcc-struct-return: Code Gen Optionsfpch-deps: Preprocessor Optionsfpch-preprocess: Preprocessor Optionsfpeel-loops: Optimize Optionsfpermissive: C++ Dialect OptionsfPIC: Code Gen Optionsfpic: Code Gen OptionsfPIE: Code Gen Optionsfpie: Code Gen Optionsfplan9-extensions: Unnamed Fieldsfpost-ipa-mem-report: Debugging Optionsfpre-ipa-mem-report: Debugging Optionsfpredictive-commoning: Optimize Optionsfprefetch-loop-arrays: Optimize Optionsfpreprocessed: Preprocessor Optionsfprofile-arcs: Other Builtinsfprofile-arcs: Debugging Optionsfprofile-correction: Optimize Optionsfprofile-dir: Optimize Optionsfprofile-generate: Optimize Optionsfprofile-use: Optimize Optionsfprofile-values: Optimize Optionsfpu: RX Optionsfrandom-seed: Debugging Optionsfreciprocal-math: Optimize Optionsfrecord-gcc-switches: Code Gen Optionsfree: Optimize Optionsfreg-struct-return: Code Gen Optionsfregmove: Optimize Optionsfrename-registers: Optimize Optionsfreorder-blocks: Optimize Optionsfreorder-blocks-and-partition: Optimize Optionsfreorder-functions: Optimize Optionsfreplace-objc-classes: Objective-C and Objective-C++ Dialect Optionsfrepo: Template Instantiationfrepo: C++ Dialect Optionsfrerun-cse-after-loop: Optimize Optionsfreschedule-modulo-scheduled-loops: Optimize Optionsfrounding-math: Optimize Optionsfsched-critical-path-heuristic: Optimize Optionsfsched-dep-count-heuristic: Optimize Optionsfsched-group-heuristic: Optimize Optionsfsched-last-insn-heuristic: Optimize Optionsfsched-pressure: Optimize Optionsfsched-rank-heuristic: Optimize Optionsfsched-spec-insn-heuristic: Optimize Optionsfsched-spec-load: Optimize Optionsfsched-spec-load-dangerous: Optimize Optionsfsched-stalled-insns: Optimize Optionsfsched-stalled-insns-dep: Optimize Optionsfsched-verbose: Debugging Optionsfsched2-use-superblocks: Optimize Optionsfschedule-insns: Optimize Optionsfschedule-insns2: Optimize Optionsfsection-anchors: Optimize Optionsfsel-sched-pipelining: Optimize Optionsfsel-sched-pipelining-outer-loops: Optimize Optionsfselective-scheduling: Optimize Optionsfselective-scheduling2: Optimize Optionsfshort-double: Code Gen Optionsfshort-enums: Non-bugsfshort-enums: Type Attributesfshort-enums: Structures unions enumerations and bit-fields implementationfshort-enums: Code Gen Optionsfshort-wchar: Code Gen Optionsfshrink-wrap: Optimize Optionsfsignaling-nans: Optimize Optionsfsigned-bitfields: Non-bugsfsigned-bitfields: C Dialect Optionsfsigned-char: Characters implementationfsigned-char: C Dialect Optionsfsingle-precision-constant: Optimize Optionsfsplit-ivs-in-unroller: Optimize Optionsfsplit-stack: Function Attributesfsplit-stack: Code Gen Optionsfsplit-wide-types: Optimize Optionsfstack-check: Code Gen Optionsfstack-limit-register: Code Gen Optionsfstack-limit-symbol: Code Gen Optionsfstack-protector: Optimize Optionsfstack-protector-all: Optimize Optionsfstack-usage: Debugging Optionsfstats: C++ Dialect Optionsfstrict-aliasing: Optimize Optionsfstrict-enums: C++ Dialect Optionsfstrict-overflow: Optimize Optionsfstrict-volatile-bitfields: Code Gen Optionsfsyntax-only: Warning Optionsftabstop: Preprocessor Optionsftemplate-depth: C++ Dialect Optionsftest-coverage: Debugging Optionsfthread-jumps: Optimize Optionsftime-report: Debugging Optionsftls-model: Code Gen Optionsftracer: Optimize Optionsftrack-macro-expansion: Preprocessor Optionsftrapv: Code Gen Optionsftree-bit-ccp: Optimize Optionsftree-builtin-call-dce: Optimize Optionsftree-ccp: Optimize Optionsftree-ch: Optimize Optionsftree-copy-prop: Optimize Optionsftree-copyrename: Optimize Optionsftree-dce: Optimize Optionsftree-dominator-opts: Optimize Optionsftree-dse: Optimize Optionsftree-forwprop: Optimize Optionsftree-fre: Optimize Optionsftree-loop-im: Optimize Optionsftree-loop-ivcanon: Optimize Optionsftree-loop-linear: Optimize Optionsftree-loop-optimize: Optimize Optionsftree-parallelize-loops: Optimize Optionsftree-phiprop: Optimize Optionsftree-pre: Optimize Optionsftree-pta: Optimize Optionsftree-reassoc: Optimize Optionsftree-sink: Optimize Optionsftree-slp-vectorize: Optimize Optionsftree-sra: Optimize Optionsftree-ter: Optimize Optionsftree-vect-loop-version: Optimize Optionsftree-vectorize: Optimize Optionsftree-vectorizer-verbose: Debugging Optionsftree-vrp: Optimize Optionsfunit-at-a-time: Optimize Optionsfunroll-all-loops: Optimize Optionsfunroll-loops: Optimize Optionsfunsafe-loop-optimizations: Optimize Optionsfunsafe-math-optimizations: Optimize Optionsfunsigned-bitfields: Non-bugsfunsigned-bitfields: Structures unions enumerations and bit-fields implementationfunsigned-bitfields: C Dialect Optionsfunsigned-char: Characters implementationfunsigned-char: C Dialect Optionsfunswitch-loops: Optimize Optionsfunwind-tables: Code Gen Optionsfuse-cxa-atexit: C++ Dialect Optionsfvar-tracking: Debugging Optionsfvar-tracking-assignments: Debugging Optionsfvar-tracking-assignments-toggle: Debugging Optionsfvariable-expansion-in-unroller: Optimize Optionsfvect-cost-model: Optimize Optionsfverbose-asm: Code Gen Optionsfvisibility: Code Gen Optionsfvisibility-inlines-hidden: C++ Dialect Optionsfvisibility-ms-compat: C++ Dialect Optionsfvpt: Optimize Optionsfweb: Optimize Optionsfwhole-program: Optimize Optionsfwide-exec-charset: Preprocessor Optionsfworking-directory: Preprocessor Optionsfwrapv: Code Gen Optionsfzero-link: Objective-C and Objective-C++ Dialect OptionsG: System V OptionsG: RS/6000 and PowerPC OptionsG: MIPS OptionsG: M32R/D Optionsg: Debugging Optionsgcoff: Debugging Optionsgdwarf-version: Debugging Optionsgen-decls: Objective-C and Objective-C++ Dialect Optionsgfull: Darwin Optionsggdb: Debugging Optionsgno-record-gcc-switches: Debugging Optionsgno-strict-dwarf: Debugging Optionsgrecord-gcc-switches: Debugging Optionsgstabs: Debugging Optionsgstabs+: Debugging Optionsgstrict-dwarf: Debugging Optionsgtoggle: Debugging Optionsgused: Darwin Optionsgvms: Debugging Optionsgxcoff: Debugging Optionsgxcoff+: Debugging OptionsH: Preprocessor Optionsheaderpad_max_install_names: Darwin Optionshelp: Preprocessor Optionshelp: Overall OptionsI: Directory OptionsI: Preprocessor OptionsI-: Directory OptionsI-: Preprocessor Optionsidirafter: Preprocessor Optionsiframework: Darwin Optionsimacros: Preprocessor Optionsimage_base: Darwin Optionsimultilib: Preprocessor Optionsinclude: Preprocessor Optionsinit: Darwin Optionsinstall_name: Darwin Optionsiprefix: Preprocessor Optionsiquote: Directory Optionsiquote: Preprocessor Optionsisysroot: Preprocessor Optionsisystem: Preprocessor Optionsiwithprefix: Preprocessor Optionsiwithprefixbefore: Preprocessor Optionskeep_private_externs: Darwin OptionsL: Directory Optionsl: Link Optionslobjc: Link Optionsm: RS/6000 and PowerPC OptionsM: Preprocessor Optionsm1: SH Optionsm10: PDP-11 Optionsm128bit-long-double: i386 and x86-64 Optionsm16-bit: CRIS Optionsm1reg-: Adapteva Epiphany Optionsm2: SH Optionsm210: MCore Optionsm2a: SH Optionsm2a-nofpu: SH Optionsm2a-single: SH Optionsm2a-single-only: SH Optionsm3: SH Optionsm31: S/390 and zSeries Optionsm32: TILEPro Optionsm32: TILE-Gx Optionsm32: SPARC Optionsm32: RS/6000 and PowerPC Optionsm32: i386 and x86-64 Optionsm32-bit: CRIS Optionsm32bit-doubles: RX Optionsm32r: M32R/D Optionsm32r2: M32R/D Optionsm32rx: M32R/D Optionsm340: MCore Optionsm3dnow: i386 and x86-64 Optionsm3e: SH Optionsm4: SH Optionsm4-nofpu: SH Optionsm4-single: SH Optionsm4-single-only: SH Optionsm40: PDP-11 Optionsm45: PDP-11 Optionsm4a: SH Optionsm4a-nofpu: SH Optionsm4a-single: SH Optionsm4a-single-only: SH Optionsm4al: SH Optionsm4byte-functions: MCore Optionsm5200: M680x0 Optionsm5206e: M680x0 Optionsm528x: M680x0 Optionsm5307: M680x0 Optionsm5407: M680x0 Optionsm64: TILE-Gx Optionsm64: SPARC Optionsm64: S/390 and zSeries Optionsm64: RS/6000 and PowerPC Optionsm64: i386 and x86-64 Optionsm64bit-doubles: RX Optionsm68000: M680x0 Optionsm68010: M680x0 Optionsm68020: M680x0 Optionsm68020-40: M680x0 Optionsm68020-60: M680x0 Optionsm68030: M680x0 Optionsm68040: M680x0 Optionsm68060: M680x0 Optionsm68881: M680x0 Optionsm8-bit: CRIS Optionsm96bit-long-double: i386 and x86-64 Optionsmabi: RS/6000 and PowerPC Optionsmabi: i386 and x86-64 Optionsmabi: ARM Optionsmabi=32: MIPS Optionsmabi=64: MIPS Optionsmabi=eabi: MIPS Optionsmabi=gnu: MMIX Optionsmabi=ibmlongdouble: RS/6000 and PowerPC Optionsmabi=ieeelongdouble: RS/6000 and PowerPC Optionsmabi=mmixware: MMIX Optionsmabi=n32: MIPS Optionsmabi=no-spe: RS/6000 and PowerPC Optionsmabi=o64: MIPS Optionsmabi=spe: RS/6000 and PowerPC Optionsmabicalls: MIPS Optionsmabort-on-noreturn: ARM Optionsmabsdiff: MeP Optionsmabshi: PDP-11 Optionsmac0: PDP-11 Optionsmacc-4: FRV Optionsmacc-8: FRV Optionsmaccumulate-args: AVR Optionsmaccumulate-outgoing-args: SH Optionsmaccumulate-outgoing-args: i386 and x86-64 Optionsmaddress-space-conversion: SPU Optionsmadjust-unroll: SH Optionsmads: RS/6000 and PowerPC Optionsmaix-struct-return: RS/6000 and PowerPC Optionsmaix32: RS/6000 and PowerPC Optionsmaix64: RS/6000 and PowerPC Optionsmalign-300: H8/300 Optionsmalign-double: i386 and x86-64 Optionsmalign-int: M680x0 Optionsmalign-labels: FRV Optionsmalign-loops: M32R/D Optionsmalign-natural: RS/6000 and PowerPC Optionsmalign-power: RS/6000 and PowerPC Optionsmall-opts: MeP Optionsmalloc-cc: FRV Optionsmalpha-as: DEC Alpha Optionsmaltivec: RS/6000 and PowerPC Optionsmam33: MN10300 Optionsmam33-2: MN10300 Optionsmam34: MN10300 Optionsmandroid: GNU/Linux Optionsmapcs: ARM Optionsmapcs-frame: ARM Optionsmapp-regs: V850 Optionsmapp-regs: SPARC Optionsmarch: S/390 and zSeries Optionsmarch: MIPS Optionsmarch: M680x0 Optionsmarch: i386 and x86-64 Optionsmarch: HPPA Optionsmarch: CRIS Optionsmarch: C6X Optionsmarch: ARM Optionsmarm: ARM Optionsmas100-syntax: RX Optionsmasm=dialect: i386 and x86-64 Optionsmatomic-updates: SPU Optionsmauto-pic: IA-64 Optionsmaverage: MeP Optionsmavoid-indexed-addresses: RS/6000 and PowerPC Optionsmax-vect-align: Adapteva Epiphany Optionsmb: SH Optionsmbackchain: S/390 and zSeries Optionsmbarrel-shift-enabled: LM32 Optionsmbase-addresses: MMIX Optionsmbased=: MeP Optionsmbcopy: PDP-11 Optionsmbcopy-builtin: PDP-11 Optionsmbig: RS/6000 and PowerPC Optionsmbig-endian: RS/6000 and PowerPC Optionsmbig-endian: MCore Optionsmbig-endian: IA-64 Optionsmbig-endian: C6X Optionsmbig-endian: ARM Optionsmbig-endian-data: RX Optionsmbig-switch: V850 Optionsmbig-switch: HPPA Optionsmbigtable: SH Optionsmbionic: GNU/Linux Optionsmbit-align: RS/6000 and PowerPC Optionsmbit-ops: CR16 Optionsmbitfield: M680x0 Optionsmbitops: SH Optionsmbitops: MeP Optionsmblock-move-inline-limit: RS/6000 and PowerPC Optionsmbranch-cheap: PDP-11 Optionsmbranch-cost: MIPS Optionsmbranch-cost: AVR Optionsmbranch-cost: Adapteva Epiphany Optionsmbranch-cost=num: SH Optionsmbranch-cost=number: M32R/D Optionsmbranch-expensive: PDP-11 Optionsmbranch-hints: SPU Optionsmbranch-likely: MIPS Optionsmbranch-predict: MMIX Optionsmbss-plt: RS/6000 and PowerPC Optionsmbuild-constants: DEC Alpha Optionsmbwx: DEC Alpha Optionsmc68000: M680x0 Optionsmc68020: M680x0 Optionsmc=: MeP Optionsmcache-size: SPU Optionsmcall-eabi: RS/6000 and PowerPC Optionsmcall-freebsd: RS/6000 and PowerPC Optionsmcall-linux: RS/6000 and PowerPC Optionsmcall-netbsd: RS/6000 and PowerPC Optionsmcall-prologues: AVR Optionsmcall-sysv: RS/6000 and PowerPC Optionsmcall-sysv-eabi: RS/6000 and PowerPC Optionsmcall-sysv-noeabi: RS/6000 and PowerPC Optionsmcallee-super-interworking: ARM Optionsmcaller-super-interworking: ARM Optionsmcallgraph-data: MCore Optionsmcbranchdi: SH Optionsmcc-init: CRIS Optionsmcfv4e: M680x0 Optionsmcheck-zero-division: MIPS Optionsmcirrus-fix-invalid-insns: ARM Optionsmcix: DEC Alpha Optionsmcld: i386 and x86-64 Optionsmclip: MeP Optionsmcmodel: SPARC Optionsmcmodel=kernel: i386 and x86-64 Optionsmcmodel=large: RS/6000 and PowerPC Optionsmcmodel=large: i386 and x86-64 Optionsmcmodel=medium: RS/6000 and PowerPC Optionsmcmodel=medium: i386 and x86-64 Optionsmcmodel=small: RS/6000 and PowerPC Optionsmcmodel=small: i386 and x86-64 Optionsmcmove: Adapteva Epiphany Optionsmcmpb: RS/6000 and PowerPC Optionsmcmpeqdi: SH Optionsmcode-readable: MIPS Optionsmcond-exec: FRV Optionsmcond-move: FRV Optionsmconfig=: MeP Optionsmconsole: i386 and x86-64 Windows Optionsmconst-align: CRIS Optionsmconst16: Xtensa Optionsmconstant-gp: IA-64 Optionsmcop: MeP Optionsmcop32: MeP Optionsmcop64: MeP Optionsmcorea: Blackfin Optionsmcoreb: Blackfin Optionsmcpu: TILEPro Optionsmcpu: TILE-Gx Optionsmcpu: SPARC Optionsmcpu: RS/6000 and PowerPC Optionsmcpu: picoChip Optionsmcpu: M680x0 Optionsmcpu: i386 and x86-64 Optionsmcpu: FRV Optionsmcpu: DEC Alpha Optionsmcpu: CRIS Optionsmcpu: ARM Optionsmcpu32: M680x0 Optionsmcpu=: MicroBlaze Optionsmcpu=: M32C Optionsmcpu=: Blackfin Optionsmcr16c: CR16 Optionsmcr16cplus: CR16 Optionsmcrc32: i386 and x86-64 Optionsmcsync-anomaly: Blackfin Optionsmcx16: i386 and x86-64 OptionsMD: Preprocessor Optionsmdalign: SH Optionsmdata-align: CRIS Optionsmdata-model: CR16 Optionsmdc: MeP Optionsmdebug: S/390 and zSeries Optionsmdebug: M32R/D Optionsmdebug-main=prefix: IA-64/VMS Optionsmdebug-main=prefix: DEC Alpha/VMS Optionsmdec-asm: PDP-11 Optionsmdisable-callt: V850 Optionsmdisable-fpregs: HPPA Optionsmdisable-indexing: HPPA Optionsmdiv: MeP Optionsmdiv: MCore Optionsmdiv: M680x0 Optionsmdiv=strategy: SH Optionsmdivide-breaks: MIPS Optionsmdivide-enabled: LM32 Optionsmdivide-traps: MIPS Optionsmdivsi3_libfunc=name: SH Optionsmdll: i386 and x86-64 Windows Optionsmdlmzb: RS/6000 and PowerPC Optionsmdmx: MIPS Optionsmdouble: FRV Optionsmdouble-float: RS/6000 and PowerPC Optionsmdouble-float: MIPS Optionsmdsp: MIPS Optionsmdspr2: MIPS Optionsmdual-nops: SPU Optionsmdwarf2-asm: IA-64 Optionsmdword: FRV Optionsmdynamic-no-pic: RS/6000 and PowerPC Optionsmea32: SPU Optionsmea64: SPU Optionsmeabi: RS/6000 and PowerPC Optionsmearly-stop-bits: IA-64 Optionsmeb: Score Optionsmeb: MeP Optionsmel: Score Optionsmel: MeP Optionsmelf: MMIX Optionsmelf: CRIS Optionsmemb: RS/6000 and PowerPC Optionsmembedded-data: MIPS Optionsmemregs=: M32C Optionsmep: V850 Optionsmepsilon: MMIX Optionsmerror-reloc: SPU Optionsmesa: S/390 and zSeries Optionsmetrax100: CRIS Optionsmetrax4: CRIS Optionsmexplicit-relocs: MIPS Optionsmexplicit-relocs: DEC Alpha Optionsmextern-sdata: MIPS OptionsMF: Preprocessor Optionsmfast-fp: Blackfin Optionsmfast-indirect-calls: HPPA Optionsmfaster-structs: SPARC Optionsmfdpic: FRV Optionsmfentry: i386 and x86-64 Optionsmfix: DEC Alpha Optionsmfix-24k: MIPS Optionsmfix-and-continue: Darwin Optionsmfix-at697f: SPARC Optionsmfix-cortex-m3-ldrd: ARM Optionsmfix-r10000: MIPS Optionsmfix-r4000: MIPS Optionsmfix-r4400: MIPS Optionsmfix-sb1: MIPS Optionsmfix-vr4120: MIPS Optionsmfix-vr4130: MIPS Optionsmfixed-cc: FRV Optionsmfixed-range: SPU Optionsmfixed-range: SH Optionsmfixed-range: IA-64 Optionsmfixed-range: HPPA Optionsmflat: SPARC Optionsmflip-mips16: MIPS Optionsmfloat-abi: ARM Optionsmfloat-gprs: RS/6000 and PowerPC Optionsmfloat-ieee: DEC Alpha Optionsmfloat-vax: DEC Alpha Optionsmfloat32: PDP-11 Optionsmfloat64: PDP-11 Optionsmflush-func: MIPS Optionsmflush-func=name: M32R/D Optionsmflush-trap=number: M32R/D Optionsmfmaf: SPARC Optionsmfmovd: SH Optionsmforce-no-pic: Xtensa Optionsmfp: ARM Optionsmfp-exceptions: MIPS Optionsmfp-mode: Adapteva Epiphany Optionsmfp-reg: DEC Alpha Optionsmfp-rounding-mode: DEC Alpha Optionsmfp-trap-mode: DEC Alpha Optionsmfp16-format: ARM Optionsmfp32: MIPS Optionsmfp64: MIPS Optionsmfpe: ARM Optionsmfpmath: i386 and x86-64 Optionsmfpmath: Optimize Optionsmfpr-32: FRV Optionsmfpr-64: FRV Optionsmfprnd: RS/6000 and PowerPC Optionsmfpu: SPARC Optionsmfpu: RS/6000 and PowerPC Optionsmfpu: PDP-11 Optionsmfpu: ARM Optionsmfriz: RS/6000 and PowerPC Optionsmfull-toc: RS/6000 and PowerPC Optionsmfused-madd: Xtensa Optionsmfused-madd: SH Optionsmfused-madd: S/390 and zSeries Optionsmfused-madd: RS/6000 and PowerPC Optionsmfused-madd: MIPS Optionsmfused-madd: IA-64 Optionsmg: VAX OptionsMG: Preprocessor Optionsmgas: HPPA Optionsmgas: DEC Alpha Optionsmgen-cell-microcode: RS/6000 and PowerPC Optionsmgettrcost=number: SH Optionsmglibc: GNU/Linux Optionsmgnu: VAX Optionsmgnu-as: IA-64 Optionsmgnu-ld: IA-64 Optionsmgnu-ld: HPPA Optionsmgotplt: CRIS Optionsmgp32: MIPS Optionsmgp64: MIPS Optionsmgpopt: MIPS Optionsmgpr-32: FRV Optionsmgpr-64: FRV Optionsmgprel-ro: FRV Optionsmh: H8/300 Optionsmhalf-reg-file: Adapteva Epiphany Optionsmhard-dfp: S/390 and zSeries Optionsmhard-dfp: RS/6000 and PowerPC Optionsmhard-float: SPARC Optionsmhard-float: S/390 and zSeries Optionsmhard-float: RS/6000 and PowerPC Optionsmhard-float: MIPS Optionsmhard-float: MicroBlaze Optionsmhard-float: M680x0 Optionsmhard-float: FRV Optionsmhard-quad-float: SPARC Optionsmhardlit: MCore Optionsmhint-max-distance: SPU Optionsmhint-max-nops: SPU Optionsmhitachi: SH Optionsmhp-ld: HPPA Optionsmicplb: Blackfin Optionsmid-shared-library: Blackfin Optionsmieee: SH Optionsmieee: DEC Alpha Optionsmieee-conformant: DEC Alpha Optionsmieee-fp: i386 and x86-64 Optionsmieee-with-inexact: DEC Alpha Optionsmilp32: IA-64 Optionsmimpure-text: Solaris 2 Optionsmincoming-stack-boundary: i386 and x86-64 Optionsmindexed-addressing: SH Optionsminline-all-stringops: i386 and x86-64 Optionsminline-float-divide-max-throughput: IA-64 Optionsminline-float-divide-min-latency: IA-64 Optionsminline-ic_invalidate: SH Optionsminline-int-divide-max-throughput: IA-64 Optionsminline-int-divide-min-latency: IA-64 Optionsminline-plt: FRV Optionsminline-plt: Blackfin Optionsminline-sqrt-max-throughput: IA-64 Optionsminline-sqrt-min-latency: IA-64 Optionsminline-stringops-dynamically: i386 and x86-64 Optionsminsert-sched-nops: RS/6000 and PowerPC Optionsmint-register: RX Optionsmint16: PDP-11 Optionsmint32: PDP-11 Optionsmint32: H8/300 Optionsmint32: CR16 Optionsmint8: AVR Optionsminterlink-mips16: MIPS Optionsminvalid-symbols: SH Optionsmio-volatile: MeP Optionsmips1: MIPS Optionsmips16: MIPS Optionsmips2: MIPS Optionsmips3: MIPS Optionsmips32: MIPS Optionsmips32r2: MIPS Optionsmips3d: MIPS Optionsmips4: MIPS Optionsmips64: MIPS Optionsmips64r2: MIPS Optionsmisel: RS/6000 and PowerPC Optionsmisize: SH Optionsmissue-rate=number: M32R/D Optionsmivc2: MeP Optionsmjump-in-delay: HPPA Optionsmkernel: Darwin Optionsmknuthdiv: MMIX Optionsml: SH Optionsml: MeP Optionsmlarge-data: DEC Alpha Optionsmlarge-data-threshold=number: i386 and x86-64 Optionsmlarge-mem: SPU Optionsmlarge-text: DEC Alpha Optionsmleadz: MeP Optionsmleaf-id-shared-library: Blackfin Optionsmlibfuncs: MMIX Optionsmlibrary-pic: FRV Optionsmlinked-fp: FRV Optionsmlinker-opt: HPPA Optionsmlinux: CRIS Optionsmlittle: RS/6000 and PowerPC Optionsmlittle-endian: SPARC Optionsmlittle-endian: RS/6000 and PowerPC Optionsmlittle-endian: MCore Optionsmlittle-endian: IA-64 Optionsmlittle-endian: C6X Optionsmlittle-endian: ARM Optionsmlittle-endian-data: RX Optionsmliw: MN10300 Optionsmllsc: MIPS Optionsmlocal-sdata: MIPS Optionsmlong-calls: V850 Optionsmlong-calls: MIPS Optionsmlong-calls: FRV Optionsmlong-calls: Blackfin Optionsmlong-calls: ARM Optionsmlong-calls: Adapteva Epiphany Optionsmlong-double-128: S/390 and zSeries Optionsmlong-double-64: S/390 and zSeries Optionsmlong-load-store: HPPA Optionsmlong32: MIPS Optionsmlong64: MIPS Optionsmlongcall: RS/6000 and PowerPC Optionsmlongcalls: Xtensa Optionsmlow-64k: Blackfin Optionsmlp64: IA-64 Optionsmm: MeP OptionsMM: Preprocessor Optionsmmac: Score Optionsmmac: CR16 Optionsmmad: MIPS Optionsmmalloc64: IA-64/VMS Optionsmmalloc64: DEC Alpha/VMS Optionsmmax: DEC Alpha Optionsmmax-constant-size: RX Optionsmmax-stack-frame: CRIS Optionsmmcount-ra-address: MIPS Optionsmmcu: AVR OptionsMMD: Preprocessor Optionsmmedia: FRV Optionsmmemcpy: MIPS Optionsmmemcpy: MicroBlaze Optionsmmemory-latency: DEC Alpha Optionsmmemory-model: SPARC Optionsmmfcrf: RS/6000 and PowerPC Optionsmmfpgpr: RS/6000 and PowerPC Optionsmminimal-toc: RS/6000 and PowerPC Optionsmminmax: MeP Optionsmmmx: i386 and x86-64 Optionsmmodel=large: M32R/D Optionsmmodel=medium: M32R/D Optionsmmodel=small: M32R/D Optionsmmovbe: i386 and x86-64 Optionsmmt: MIPS Optionsmmul: RL78 Optionsmmul-bug-workaround: CRIS Optionsmmuladd: FRV Optionsmmulhw: RS/6000 and PowerPC Optionsmmult: MeP Optionsmmult-bug: MN10300 Optionsmmulti-cond-exec: FRV Optionsmmulticore: Blackfin Optionsmmultiple: RS/6000 and PowerPC Optionsmmvcle: S/390 and zSeries Optionsmmvme: RS/6000 and PowerPC Optionsmn: H8/300 Optionsmnested-cond-exec: FRV Optionsmnew-mnemonics: RS/6000 and PowerPC Optionsmnhwloop: Score Optionsmno-3dnow: i386 and x86-64 Optionsmno-4byte-functions: MCore Optionsmno-abicalls: MIPS Optionsmno-abshi: PDP-11 Optionsmno-ac0: PDP-11 Optionsmno-address-space-conversion: SPU Optionsmno-align-double: i386 and x86-64 Optionsmno-align-int: M680x0 Optionsmno-align-loops: M32R/D Optionsmno-align-stringops: i386 and x86-64 Optionsmno-altivec: RS/6000 and PowerPC Optionsmno-am33: MN10300 Optionsmno-app-regs: V850 Optionsmno-app-regs: SPARC Optionsmno-as100-syntax: RX Optionsmno-atomic-updates: SPU Optionsmno-avoid-indexed-addresses: RS/6000 and PowerPC Optionsmno-backchain: S/390 and zSeries Optionsmno-base-addresses: MMIX Optionsmno-bit-align: RS/6000 and PowerPC Optionsmno-bitfield: M680x0 Optionsmno-branch-likely: MIPS Optionsmno-branch-predict: MMIX Optionsmno-bwx: DEC Alpha Optionsmno-callgraph-data: MCore Optionsmno-check-zero-division: MIPS Optionsmno-cirrus-fix-invalid-insns: ARM Optionsmno-cix: DEC Alpha Optionsmno-clearbss: MicroBlaze Optionsmno-cmpb: RS/6000 and PowerPC Optionsmno-cond-exec: FRV Optionsmno-cond-move: FRV Optionsmno-const-align: CRIS Optionsmno-const16: Xtensa Optionsmno-crt0: MN10300 Optionsmno-csync-anomaly: Blackfin Optionsmno-data-align: CRIS Optionsmno-debug: S/390 and zSeries Optionsmno-div: MCore Optionsmno-div: M680x0 Optionsmno-dlmzb: RS/6000 and PowerPC Optionsmno-double: FRV Optionsmno-dsp: MIPS Optionsmno-dspr2: MIPS Optionsmno-dwarf2-asm: IA-64 Optionsmno-dword: FRV Optionsmno-eabi: RS/6000 and PowerPC Optionsmno-early-stop-bits: IA-64 Optionsmno-eflags: FRV Optionsmno-embedded-data: MIPS Optionsmno-ep: V850 Optionsmno-epsilon: MMIX Optionsmno-explicit-relocs: MIPS Optionsmno-explicit-relocs: DEC Alpha Optionsmno-extern-sdata: MIPS Optionsmno-fancy-math-387: i386 and x86-64 Optionsmno-faster-structs: SPARC Optionsmno-fix: DEC Alpha Optionsmno-fix-24k: MIPS Optionsmno-fix-r10000: MIPS Optionsmno-fix-r4000: MIPS Optionsmno-fix-r4400: MIPS Optionsmno-flat: SPARC Optionsmno-float32: PDP-11 Optionsmno-float64: PDP-11 Optionsmno-flush-func: M32R/D Optionsmno-flush-trap: M32R/D Optionsmno-fmaf: SPARC Optionsmno-fp-in-toc: RS/6000 and PowerPC Optionsmno-fp-regs: DEC Alpha Optionsmno-fp-ret-in-387: i386 and x86-64 Optionsmno-fprnd: RS/6000 and PowerPC Optionsmno-fpu: SPARC Optionsmno-fused-madd: Xtensa Optionsmno-fused-madd: S/390 and zSeries Optionsmno-fused-madd: RS/6000 and PowerPC Optionsmno-fused-madd: MIPS Optionsmno-fused-madd: IA-64 Optionsmno-gnu-as: IA-64 Optionsmno-gnu-ld: IA-64 Optionsmno-gotplt: CRIS Optionsmno-gpopt: MIPS Optionsmno-hard-dfp: S/390 and zSeries Optionsmno-hard-dfp: RS/6000 and PowerPC Optionsmno-hardlit: MCore Optionsmno-id-shared-library: Blackfin Optionsmno-ieee-fp: i386 and x86-64 Optionsmno-inline-float-divide: IA-64 Optionsmno-inline-int-divide: IA-64 Optionsmno-inline-sqrt: IA-64 Optionsmno-int16: PDP-11 Optionsmno-int32: PDP-11 Optionsmno-interlink-mips16: MIPS Optionsmno-interrupts: AVR Optionsmno-isel: RS/6000 and PowerPC Optionsmno-knuthdiv: MMIX Optionsmno-leaf-id-shared-library: Blackfin Optionsmno-libfuncs: MMIX Optionsmno-llsc: MIPS Optionsmno-local-sdata: MIPS Optionsmno-long-calls: V850 Optionsmno-long-calls: MIPS Optionsmno-long-calls: HPPA Optionsmno-long-calls: Blackfin Optionsmno-long-calls: ARM Optionsmno-longcall: RS/6000 and PowerPC Optionsmno-longcalls: Xtensa Optionsmno-low-64k: Blackfin Optionsmno-lsim: MCore Optionsmno-lsim: FR30 Optionsmno-mad: MIPS Optionsmno-max: DEC Alpha Optionsmno-mcount-ra-address: MIPS Optionsmno-mdmx: MIPS Optionsmno-media: FRV Optionsmno-memcpy: MIPS Optionsmno-mfcrf: RS/6000 and PowerPC Optionsmno-mfpgpr: RS/6000 and PowerPC Optionsmno-mips16: MIPS Optionsmno-mips3d: MIPS Optionsmno-mmx: i386 and x86-64 Optionsmno-mt: MIPS Optionsmno-mul-bug-workaround: CRIS Optionsmno-muladd: FRV Optionsmno-mulhw: RS/6000 and PowerPC Optionsmno-mult-bug: MN10300 Optionsmno-multi-cond-exec: FRV Optionsmno-multiple: RS/6000 and PowerPC Optionsmno-mvcle: S/390 and zSeries Optionsmno-nested-cond-exec: FRV Optionsmno-optimize-membar: FRV Optionsmno-opts: MeP Optionsmno-pack: FRV Optionsmno-packed-stack: S/390 and zSeries Optionsmno-paired: RS/6000 and PowerPC Optionsmno-paired-single: MIPS Optionsmno-pic: IA-64 Optionsmno-pid: RX Optionsmno-plt: MIPS Optionsmno-popc: SPARC Optionsmno-popcntb: RS/6000 and PowerPC Optionsmno-popcntd: RS/6000 and PowerPC Optionsmno-postinc: Adapteva Epiphany Optionsmno-postmodify: Adapteva Epiphany Optionsmno-power: RS/6000 and PowerPC Optionsmno-power2: RS/6000 and PowerPC Optionsmno-powerpc: RS/6000 and PowerPC Optionsmno-powerpc-gfxopt: RS/6000 and PowerPC Optionsmno-powerpc-gpopt: RS/6000 and PowerPC Optionsmno-powerpc64: RS/6000 and PowerPC Optionsmno-prolog-function: V850 Optionsmno-prologue-epilogue: CRIS Optionsmno-prototype: RS/6000 and PowerPC Optionsmno-push-args: i386 and x86-64 Optionsmno-red-zone: i386 and x86-64 Optionsmno-register-names: IA-64 Optionsmno-regnames: RS/6000 and PowerPC Optionsmno-relax-immediate: MCore Optionsmno-relocatable: RS/6000 and PowerPC Optionsmno-relocatable-lib: RS/6000 and PowerPC Optionsmno-round-nearest: Adapteva Epiphany Optionsmno-rtd: M680x0 Optionsmno-scc: FRV Optionsmno-sched-ar-data-spec: IA-64 Optionsmno-sched-ar-in-data-spec: IA-64 Optionsmno-sched-br-data-spec: IA-64 Optionsmno-sched-br-in-data-spec: IA-64 Optionsmno-sched-control-spec: IA-64 Optionsmno-sched-count-spec-in-critical-path: IA-64 Optionsmno-sched-in-control-spec: IA-64 Optionsmno-sched-prefer-non-control-spec-insns: IA-64 Optionsmno-sched-prefer-non-data-spec-insns: IA-64 Optionsmno-sched-prolog: ARM Optionsmno-sdata: RS/6000 and PowerPC Optionsmno-sdata: IA-64 Optionsmno-sep-data: Blackfin Optionsmno-serialize-volatile: Xtensa Optionsmno-short: M680x0 Optionsmno-side-effects: CRIS Optionsmno-sim: RX Optionsmno-single-exit: MMIX Optionsmno-slow-bytes: MCore Optionsmno-small-exec: S/390 and zSeries Optionsmno-smartmips: MIPS Optionsmno-soft-cmpsf: Adapteva Epiphany Optionsmno-soft-float: DEC Alpha Optionsmno-space-regs: HPPA Optionsmno-spe: RS/6000 and PowerPC Optionsmno-specld-anomaly: Blackfin Optionsmno-split-addresses: MIPS Optionsmno-sse: i386 and x86-64 Optionsmno-stack-align: CRIS Optionsmno-stack-bias: SPARC Optionsmno-strict-align: RS/6000 and PowerPC Optionsmno-strict-align: M680x0 Optionsmno-string: RS/6000 and PowerPC Optionsmno-sum-in-toc: RS/6000 and PowerPC Optionsmno-sym32: MIPS Optionsmno-target-align: Xtensa Optionsmno-text-section-literals: Xtensa Optionsmno-tls-markers: RS/6000 and PowerPC Optionsmno-toc: RS/6000 and PowerPC Optionsmno-toplevel-symbols: MMIX Optionsmno-tpf-trace: S/390 and zSeries Optionsmno-unaligned-access: ARM Optionsmno-unaligned-doubles: SPARC Optionsmno-uninit-const-in-rodata: MIPS Optionsmno-update: RS/6000 and PowerPC Optionsmno-v8plus: SPARC Optionsmno-vect-double: 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Builtinsvisibility attribute: Function Attributesvliw attribute: Function Attributesvolatile applied to function: Function Attributesvprintf: Other Builtinsvscanf: Other Builtinsvsnprintf: Other Builtinsvsprintf: Other Builtinsvsscanf: Other BuiltinsW floating point suffix: Floating Typesw floating point suffix: Floating Typeswarn_unused_result attribute: Function Attributeswarning function attribute: Function Attributesweak attribute: Function Attributesweakref attribute: Function Attributesy0: Other Builtinsy0f: Other Builtinsy0l: Other Builtinsy1: Other Builtinsy1f: Other Builtinsy1l: Other Builtinsyn: Other Builtinsynf: Other Builtinsynl: Other Builtins[1] On some systems, ‘gcc -shared’ needs to build supplementary stub code for constructors to work. On multi-libbed systems, ‘gcc -shared’ must select the correct support libraries to link against. Failing to supply the correct flags may lead to subtle defects. Supplying them in cases where they are not necessary is innocuous.
[2] Future versions of GCC may zero-extend, or use
a target-defined ptr_extend pattern. Do not rely on sign extension.
[3] The analogous feature in Fortran is called an assigned goto, but that name seems inappropriate in C, where one can do more than simply store label addresses in label variables.
[4] A file's basename was the name stripped of all leading path information and of trailing suffixes, such as ‘.h’ or ‘.C’ or ‘.cc’.
[5] The C++ standard just uses the term “dependent” for names that depend on the type or value of template parameters. This shorter term will also be used in the rest of this section.