[all-commits] [llvm/llvm-project] e99d8b: [PowerPC] eliminate RLWINM instruction following L...

[zhijian lin via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: e99d8bb0dcc5c41268714ad083f6b2924b789cf7
      https://github.com/llvm/llvm-project/commit/e99d8bb0dcc5c41268714ad083f6b2924b789cf7
  Author: zhijian lin <zhijian at ca.ibm.com>
  Date:   2025-06-25 (Wed, 25 Jun 2025)

  Changed paths:
    M llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
    M llvm/test/CodeGen/PowerPC/PR35812-neg-cmpxchg.ll
    M llvm/test/CodeGen/PowerPC/all-atomics.ll
    M llvm/test/CodeGen/PowerPC/atomics-regression.ll
    M llvm/test/CodeGen/PowerPC/loop-comment.ll

  Log Message:
  -----------
  [PowerPC] eliminate RLWINM instruction following LBARX as possible (#144089)

LBARX loads a byte from memory into a register, automatically setting
the remaining bits of the register to zero. If a subsequent RLWINM
instruction is used to clear those same bits (which LBARX has already
set to zero), the RLWINM is redundant and can be eliminated.

 these redundant clear instructions are introduced by 85a9f2e14859b.



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