[PATCH] D85807: [Target] Cache the command line derived feature map in TargetOptions.

Wed Aug 12 10:27:01 PDT 2020

nickdesaulniers accepted this revision.
nickdesaulniers added a comment.
This revision is now accepted and ready to land.

LGTM; comparing the report at the bottom of https://reviews.llvm.org/D85257#2197114, repasted (before this patch):

  +    3.59%  clang-12                   [.] llvm::X86::getImpliedFeatures
  -    3.36%  clang-12                   [.] llvm::StringMapImpl::LookupBucketFor
     - 3.32% llvm::StringMapImpl::LookupBucketFor
        - 1.24% llvm::StringMap<bool, llvm::MallocAllocator>::try_emplace<>
           + 1.24% clang::targets::X86TargetInfo::setFeatureEnabled

  Elapsed (wall clock) time (h:mm:ss or m:ss): 0:53.39

(After this patch):
A profile of a full x86_64 build with this applied, none of the above appear in the profile.  `clang::targets::X86TargetInfo::setFeatureEnabled`, does but near at the bottom with < 0.00%.  So this shaves another ~5% off build times!

  Elapsed (wall clock) time (h:mm:ss or m:ss): 0:50.98

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D85807/new/

https://reviews.llvm.org/D85807