[all-commits] [llvm/llvm-project] 4fdc28: [InstCombine] Infer nsw flag for `(X <<nuw C1) >>u...

[Yingwei Zheng via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 4fdc289d4ac26970749ca24802931bd662a2a1f8
      https://github.com/llvm/llvm-project/commit/4fdc289d4ac26970749ca24802931bd662a2a1f8
  Author: Yingwei Zheng <dtcxzyw2333 at gmail.com>
  Date:   2023-11-16 (Thu, 16 Nov 2023)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
    M llvm/test/Transforms/InstCombine/canonicalize-shl-lshr-to-masking.ll
    M llvm/test/Transforms/InstCombine/shift.ll

  Log Message:
  -----------
  [InstCombine] Infer nsw flag for `(X <<nuw C1) >>u C --> X << (C1 - C)` (#72407)

Alive2: https://alive2.llvm.org/ce/z/nnHAPy
This missed optimization is discovered with the help of
https://github.com/AliveToolkit/alive2/pull/962.