[all-commits] [llvm/llvm-project] 935609: Revert "[AMDGPU] Ressociate patterns with sub to u...

[chenglin.bi via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 9356097206a17eb781180d5f895b52f8b0333f8e
      https://github.com/llvm/llvm-project/commit/9356097206a17eb781180d5f895b52f8b0333f8e
  Author: chenglin.bi <bichenglin5980 at gmail.com>
  Date:   2023-04-19 (Wed, 19 Apr 2023)

  Changed paths:
    M llvm/lib/Target/AMDGPU/SIISelLowering.cpp
    M llvm/lib/Target/AMDGPU/SIISelLowering.h
    M llvm/test/CodeGen/AMDGPU/combine-cond-add-sub.ll
    R llvm/test/CodeGen/AMDGPU/reassoc-sub-add.ll

  Log Message:
  -----------
  Revert "[AMDGPU] Ressociate patterns with sub to use SALU"

The patch will caused dead loop because of DAGCombiner's canonicalization:
  // (x + C) - y  ->  (x - y) + C
  // y - (x + C)  ->  (y - x) - C
  // (x - C) - y  ->  (x - y) - C
  // (C - x) - y  ->  C - (x + y)

This reverts commit b3529b5bf3ba2cd7f38665de16450afefb263c9b.