From: Aaron Ballman Date: Fri, 3 May 2013 02:39:21 +0000 (+0000) Subject: Correctly testing for AVX support in x86 based off code from Hosts.cpp. X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=f57563b61b0b3604a25c6388714068713e027e18;p=oota-llvm.git Correctly testing for AVX support in x86 based off code from Hosts.cpp. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180991 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/lib/Target/X86/X86Subtarget.cpp b/lib/Target/X86/X86Subtarget.cpp index 448d2e6054c..90e6b700ef5 100644 --- a/lib/Target/X86/X86Subtarget.cpp +++ b/lib/Target/X86/X86Subtarget.cpp @@ -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;