[PATCH] D141464: [X86]: Match (xor TSize - 1, ctlz) to `bsr` instead of `lzcnt` + `xor`

[Phoebe Wang via Phabricator via llvm-commits]

pengfei added inline comments.


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Comment at: llvm/test/CodeGen/X86/clz.ll:968
 ; the most significant bit, which is what 'bsr' does natively.
 ; FIXME: We should probably select BSR instead of LZCNT in these circumstances.
 define i32 @ctlz_bsr(i32 %n) {
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The FIXME is solved :)
But maybe better to leave a comment the `FASTLZCNT` is intended.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D141464/new/

https://reviews.llvm.org/D141464