base/dispatch-x86ish.S (dispatch_x86ish_cpuid): Skip `EFLAGS_ID' dance on AMD64.

[catacomb] / base / dispatch-x86ish.S

diff --git a/base/dispatch-x86ish.S b/base/dispatch-x86ish.S
index 9510f9690de37311536d265128d5b18463f6a78f..3a14c3962b861ad5888b89c1be41f926c6fba218 100644 (file)
--- a/base/dispatch-x86ish.S
+++ b/base/dispatch-x86ish.S
@@ -67,7 +67,9 @@ FUNC(dispatch_x86ish_cpuid)
   endprologue
 
        // First, check that this is even a thing, using the complicated
-       // dance with the flags register.
+       // dance with the flags register.  This is unnecessary on AMD64,
+       // which postdates the introduction of `cpuid'.
+#if CPUFAM_X86
        pushf
        pop     DX                      // current flags in d
 
@@ -86,6 +88,7 @@ FUNC(dispatch_x86ish_cpuid)
        pop     DX
        test    edx, EFLAGS_ID
        jnz     8f
+#endif
 
        // OK, that seemed to work.
        cpuid
@@ -108,6 +111,7 @@ FUNC(dispatch_x86ish_cpuid)
        ret
 
        // Failed.
+#if CPUFAM_X86
 8:     xor     eax, eax
        mov     [OUT + 0], eax
        mov     [OUT + 4], eax
@@ -115,6 +119,7 @@ FUNC(dispatch_x86ish_cpuid)
        mov     [OUT + 12], eax
        mov     eax, -1
        jmp     9b
+#endif
 ENDFUNC
 
 ///--------------------------------------------------------------------------
@@ -164,8 +169,9 @@ FUNC(dispatch_x86ish_xgetbv)
 
 #if CPUFAM_X86
 #  define Z_OUT edi
-       mov     edi, [esp + 4]
-       mov     ecx, [esp + 8]
+       pushreg edi
+       mov     edi, [esp + 8]
+       mov     ecx, [esp + 12]
 #endif
 #if CPUFAM_AMD64 && ABI_SYSV
 #  define Z_OUT rdi
@@ -182,6 +188,9 @@ FUNC(dispatch_x86ish_xgetbv)
        mov     [Z_OUT + 0], eax
        mov     [Z_OUT + 4], edx
 
+#if CPUFAM_X86
+       popreg  edi
+#endif
        ret
 
 #undef Z_OUT