anna added a comment. In D155145#4554786 <https://reviews.llvm.org/D155145#4554786>, @anna wrote:
>> Can you capture the values of EAX, EBX, ECX, and EDX after the two calls to >> getX86CpuIDAndInfoEx that have 0x7 as the first argument? Maybe there's a >> bug in CPUID on Sandy Bridge. > > Sure, on the original code before the patch you suggested right? > The two calls are: > > bool HasLeaf7 = > MaxLevel >= 7 && !getX86CpuIDAndInfoEx(0x7, 0x0, &EAX, &EBX, &ECX, > &EDX); > + llvm::errs() << "Before setting fsgsbase the value for EAX: " << EAX > + << " EBX: " << EBX << " ECX: " << ECX << " EDX: " << > EDX > + << "\n"; > > Features["fsgsbase"] = HasLeaf7 && ((EBX >> 0) & 1); > .... > bool HasLeaf7Subleaf1 = > MaxLevel >= 7 && !getX86CpuIDAndInfoEx(0x7, 0x1, &EAX, &EBX, &ECX, > &EDX); > + llvm::errs() << "Before setting sha512 the value for EAX: " << EAX > + << " EBX: " << EBX << " ECX: " << ECX << " EDX: " << > EDX > + << "\n"; > Features["sha512"] = HasLeaf7Subleaf1 && ((EAX >> 0) & 1); > ... > we set avxvnniint16 after this > > Takes a while to get a build on this machine, should have the output soon. @ctopper here is the output: Before setting fsgsbase the value for EAX: 0 EBX: 0 ECX: 0 EDX: 2617246720 // this is after the HasLeaf7 calculation Before setting sha512 the value for EAX: 0 EBX: 0 ECX: 0 EDX: 2617246720 // this is after the HasLeaf7Subleaf1 calculation So, with your patch `HasLeaf7Subleaf1` is 0 as EAX is 0. Pls let me know if you need any additional diagnostics output (we actually lose access to the machine on friday, since it is being retired!). > The documentation says that invalid subleaves of leaf 7 should return all 0s. > So we thought it was safe to check the bits of sub leaf 1 even if eax from > subleaf 0 doesn't say subleaf 1 is supported. This means the CPUID doesn't satisfy the documentation since EDX != 0 for SubLeaf1? Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D155145/new/ https://reviews.llvm.org/D155145 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
