[PATCH] D121472: [X86] combineCMP - peek through zero-extensions for X86cmp(zext(x0),0) zero tests (PR38960)

[Simon Pilgrim via Phabricator via llvm-commits]

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If we're comparing a value against zero, strip away any zero-extension and perform the comparison on the pre-extended value


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D121472

Files:
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/test/CodeGen/X86/comi-flags.ll

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