diff options
Diffstat (limited to 'libatomic/config/x86/init.c')
-rw-r--r-- | libatomic/config/x86/init.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/libatomic/config/x86/init.c b/libatomic/config/x86/init.c index 7bdec72..6f6499c 100644 --- a/libatomic/config/x86/init.c +++ b/libatomic/config/x86/init.c @@ -34,6 +34,18 @@ __libat_feat1_init (void) unsigned int eax, ebx, ecx, edx; FEAT1_REGISTER = 0; __get_cpuid (1, &eax, &ebx, &ecx, &edx); +#ifdef __x86_64__ + if ((FEAT1_REGISTER & (bit_AVX | bit_CMPXCHG16B)) + == (bit_AVX | bit_CMPXCHG16B)) + { + /* Intel SDM guarantees that 16-byte VMOVDQA on 16-byte aligned address + is atomic, but so far we don't have this guarantee from AMD. */ + unsigned int ecx2 = 0; + __get_cpuid (0, &eax, &ebx, &ecx2, &edx); + if (ecx2 != signature_INTEL_ecx) + FEAT1_REGISTER &= ~bit_AVX; + } +#endif /* See the load in load_feat1. */ __atomic_store_n (&__libat_feat1, FEAT1_REGISTER, __ATOMIC_RELAXED); return FEAT1_REGISTER; |