[all-commits] [llvm/llvm-project] 34c89e: [InstCombine] Fold `trunc nuw/nsw (x xor y) to i1`...

[Monad via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 34c89eff64cce7debb8e2d5a0d1c4d896a23e432
      https://github.com/llvm/llvm-project/commit/34c89eff64cce7debb8e2d5a0d1c4d896a23e432
  Author: Monad <yanwqmonad at gmail.com>
  Date:   2024-04-30 (Tue, 30 Apr 2024)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
    M llvm/test/Transforms/InstCombine/trunc.ll

  Log Message:
  -----------
  [InstCombine] Fold `trunc nuw/nsw (x xor y) to i1` to `x != y` (#90408)

Fold:
``` llvm
define i1 @src(i8 %x, i8 %y) {
  %xor = xor i8 %x, %y
  %r = trunc nuw/nsw i8 %xor to i1
  ret i1 %r
}

define i1 @tgt(i8 %x, i8 %y) {
  %r = icmp ne i8 %x, %y
  ret i1 %r
}
```

Proof: https://alive2.llvm.org/ce/z/dcuHmn



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