[all-commits] [llvm/llvm-project] ad3a76: [X86] combineCMP - peek through zero-extensions fo...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ad3a7654dc7dba66dafbdab0c06719174cd2b437
      https://github.com/llvm/llvm-project/commit/ad3a7654dc7dba66dafbdab0c06719174cd2b437
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2022-03-13 (Sun, 13 Mar 2022)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/comi-flags.ll

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

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

Fixes #38308

Differential Revision: https://reviews.llvm.org/D121472