[PATCH] D17289: [X86] Fix False Data Dependency in popcnt

[Asaf Badouh via llvm-commits]

AsafBadouh created this revision.
AsafBadouh added reviewers: aaboud, zansari, DavidKreitzer.
AsafBadouh added a subscriber: llvm-commits.
AsafBadouh set the repository for this revision to rL LLVM.

popcnt have a false dependency on the destination register dest, the instruction will wait until dest is ready before executing.

more details in:
http://stackoverflow.com/questions/25078285/replacing-a-32-bit-loop-count-variable-with-64-bit-introduces-crazy-performance


Repository:
  rL LLVM

http://reviews.llvm.org/D17289

Files:
  ../llvm/lib/Target/X86/CMakeLists.txt
  ../llvm/lib/Target/X86/X86.h
  ../llvm/lib/Target/X86/X86PopcntOpt.cpp
  ../llvm/lib/Target/X86/X86TargetMachine.cpp
  ../llvm/test/CodeGen/X86/popcnt.ll

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