[PATCH] D94856: [X86] WIP Improve optimizeCompareInstr for signed comparisons after logical operations.

Tue Mar 30 18:46:40 PDT 2021

craig.topper added a comment.

In D94856#2657970 <https://reviews.llvm.org/D94856#2657970>, @RKSimon wrote:

> @craig.topper Are you still hoping to deal with this one or should one of us commandeer it?

I'll pick this back up.

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Comment at: llvm/lib/Target/X86/X86InstrInfo.cpp:4058
   case X86::BZHI64rr:  case X86::BZHI64rm:
   case X86::LZCNT16rr: case X86::LZCNT16rm:
   case X86::LZCNT32rr: case X86::LZCNT32rm:
----------------
Surprisingly LZCNT and TZCNT don't define the value of the O flag so this is wrong. POPCNT does clear it.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D94856/new/

https://reviews.llvm.org/D94856