search for: d21379

...5 AM, Sanjay Patel via llvm-dev < llvm-dev at lists.llvm.org> wrote: > Yes - I was thinking of FeatureFastScalarFSQRT / FeatureFastVectorFSQRT > which are used by isFsqrtCheap(). These were added to override the default > x86 sqrt estimate codegen with: > https://reviews.llvm.org/D21379 > > But I'm not sure we really need that kind of hack. Can we adjust the > attribute in clang based on the target cpu? Ie, if you have something like: > $ clang -O2 -march=skylake-avx512 foo.c > > Then you can detect that in the clang driver and pass > -mprefer-vector-width...

...vm-dev < > llvm-dev at lists.llvm.org> wrote: > >> Yes - I was thinking of FeatureFastScalarFSQRT / FeatureFastVectorFSQRT >> which are used by isFsqrtCheap(). These were added to override the default >> x86 sqrt estimate codegen with: >> https://reviews.llvm.org/D21379 >> >> But I'm not sure we really need that kind of hack. Can we adjust the >> attribute in clang based on the target cpu? Ie, if you have something like: >> $ clang -O2 -march=skylake-avx512 foo.c >> >> Then you can detect that in the clang driver and pass &g...

...Yes - I was thinking of FeatureFastScalarFSQRT / >> FeatureFastVectorFSQRT which are used by isFsqrtCheap(). >> These were added to override the default x86 sqrt >> estimate codegen with: >> https://reviews.llvm.org/D21379 >> >> But I'm not sure we really need that kind of hack. Can we >> adjust the attribute in clang based on the target cpu? >> Ie, if you have something like: >> $ clang -O2 -march=skylake-avx512 foo.c >> >>...

Are you referring to the X86TargetLowering::isFsqrtCheap hook? ~Craig On Fri, Nov 10, 2017 at 7:39 AM, Sanjay Patel <spatel at rotateright.com> wrote: > We can tie a user preference / override to a CPU model. We do something > like that for square root estimates already (although it does use a > SubtargetFeature currently for x86; ideally, we'd key that off of something >

...gt;>> >>>>> Yes - I was thinking of FeatureFastScalarFSQRT / >>>>> FeatureFastVectorFSQRT which are used by isFsqrtCheap(). These were added >>>>> to override the default x86 sqrt estimate codegen with: >>>>> https://reviews.llvm.org/D21379 >>>>> >>>>> But I'm not sure we really need that kind of hack. Can we adjust the >>>>> attribute in clang based on the target cpu? Ie, if you have something like: >>>>> $ clang -O2 -march=skylake-avx512 foo.c >>>>> >&...