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Correctly testing for AVX support in x86 based off code from Hosts.cpp.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180991 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Aaron Ballman 2013-05-03 02:39:21 +00:00
parent ceb7fb8935
commit f57563b61b
1 changed files with 18 additions and 1 deletions
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19
lib/Target/X86/X86Subtarget.cpp
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@ -170,6 +170,21 @@ bool X86Subtarget::IsLegalToCallImmediateAddr(const TargetMachine &TM) const {
return isTargetELF() || TM.getRelocationModel() == Reloc::Static;
}
static bool OSHasAVXSupport() {
#if defined(__GNUC__)
// Check xgetbv; this uses a .byte sequence instead of the instruction
// directly because older assemblers do not include support for xgetbv and
// there is no easy way to conditionally compile based on the assembler used.
int rEAX, rEDX;
__asm__ (".byte 0x0f, 0x01, 0xd0" : "=a" (rEAX), "=d" (rEDX) : "c" (0));
#elif defined(_MSC_FULL_VER) && defined(_XCR_XFEATURE_ENABLED_MASK)
unsigned long long rEAX = _xgetbv(_XCR_XFEATURE_ENABLED_MASK);
#else
int rEAX = 0; // Ensures we return false
#endif
return (rEAX & 6) == 6;
}
void X86Subtarget::AutoDetectSubtargetFeatures() {
unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
unsigned MaxLevel;
@ -192,7 +207,9 @@ void X86Subtarget::AutoDetectSubtargetFeatures() {
if ((ECX >> 9) & 1) { X86SSELevel = SSSE3; ToggleFeature(X86::FeatureSSSE3);}
if ((ECX >> 19) & 1) { X86SSELevel = SSE41; ToggleFeature(X86::FeatureSSE41);}
if ((ECX >> 20) & 1) { X86SSELevel = SSE42; ToggleFeature(X86::FeatureSSE42);}
if ((ECX >> 28) & 1) { X86SSELevel = AVX; ToggleFeature(X86::FeatureAVX); }
if (((ECX >> 27) & 1) && ((ECX >> 28) & 1) && OSHasAVXSupport()) {
X86SSELevel = AVX; ToggleFeature(X86::FeatureAVX);
}
bool IsIntel = memcmp(text.c, "GenuineIntel", 12) == 0;
bool IsAMD = !IsIntel && memcmp(text.c, "AuthenticAMD", 12) == 0;