[all-commits] [llvm/llvm-project] c1f81e: [DAG] mergeStore - peek through truncates when fin...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: c1f81e7604457fa0b6c8bc03745c41d511106040
      https://github.com/llvm/llvm-project/commit/c1f81e7604457fa0b6c8bc03745c41d511106040
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2023-03-15 (Wed, 15 Mar 2023)

  Changed paths:
    M llvm/include/llvm/CodeGen/SelectionDAGNodes.h
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
    M llvm/test/CodeGen/X86/illegal-bitfield-loadstore.ll

  Log Message:
  -----------
  [DAG] mergeStore - peek through truncates when finding dead store(trunc(load())) patterns

Extend the existing store(load()) removal code to account for intermediate truncates that some targets won't remove with canCombineTruncStore - we only care about the load/store MemoryVT.

Fixes regression from D146121