From: Mark Wooding <mdw@distorted.org.uk>
Date: Thu, 26 May 2016 08:26:09 +0000 (+0100)
Subject: base/asm-common.h: Introduce simpler PIC data reference macro.
X-Git-Tag: 2.2.4~24
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/catacomb/commitdiff_plain/0c53ac58079a05cf177550684112d72489d8b97e?ds=sidebyside

base/asm-common.h: Introduce simpler PIC data reference macro.

Using the `GOT_PREL' relocation type means that we don't need to burn a
register for the GOT.
---

diff --git a/base/asm-common.h b/base/asm-common.h
index 32c05430..9c2dfb30 100644
--- a/base/asm-common.h
+++ b/base/asm-common.h
@@ -210,6 +210,22 @@ _where_am_i.\got :
 #endif
 	.endm
 
+// Load address of external symbol ADDR into REG directly.
+	.macro	leaextq	reg, addr, cond=
+#if WANT_PIC
+	ldr\cond \reg, .L$_leaextq$\@
+.L$_leaextq_pc$\@:
+	ldr\cond \reg, [pc, \reg]
+	_LIT
+	.balign	4
+.L$_leaextq$\@:
+	.word	\addr(GOT_PREL) + (. - .L$_leaextq_pc$\@ - 8)
+	_ENDLIT
+#else
+	ldr\cond \reg, =\addr
+#endif
+	.endm
+
 #endif
 
 ///--------------------------------------------------------------------------