[all-commits] [llvm/llvm-project] 967893: [DAGCombine] Fold (X & ~Y) | Y with truncated not

[Nikita Popov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 9678936f180776db4ebd960fa2eb06b3a61bc94c
      https://github.com/llvm/llvm-project/commit/9678936f180776db4ebd960fa2eb06b3a61bc94c
  Author: Nikita Popov <npopov at redhat.com>
  Date:   2022-05-05 (Thu, 05 May 2022)

  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/add-and-not.ll

  Log Message:
  -----------
  [DAGCombine] Fold (X & ~Y) | Y with truncated not

This extends the (X & ~Y) | Y to X | Y fold to also work if ~Y is
a truncated not (when taking into account the mask X). This is
done by exporting the infrastructure added in D124856 and reusing
it here.

I've retained the old value of AllowUndefs=false, though probably
this can be switched to true with extra test coverage.

Differential Revision: https://reviews.llvm.org/D124930