[all-commits] [llvm/llvm-project] 24c2ba: [InstCombine] Drop NSW when converting `shl X, BW ...

[Yingwei Zheng via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 24c2ba07ce65a5bf7d1113e05c517169d950b663
      https://github.com/llvm/llvm-project/commit/24c2ba07ce65a5bf7d1113e05c517169d950b663
  Author: Yingwei Zheng <dtcxzyw2333 at gmail.com>
  Date:   2025-01-05 (Sun, 05 Jan 2025)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
    M llvm/test/Transforms/InstCombine/rem-mul-shl.ll

  Log Message:
  -----------
  [InstCombine] Drop NSW when converting `shl X, BW - 1` back into mul (#121633)

`X <<s BW - 1` and `X *s INT_MIN` are not equivalent.
Alive2: https://alive2.llvm.org/ce/z/MKKFrj
Closes https://github.com/llvm/llvm-project/issues/121584



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