[all-commits] [llvm/llvm-project] ff2385: [DAG] Fold (abds x, y) -> (abdu x, y) iff both arg...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ff23856c1c0cc4a8737e7338b084297e6877e910
      https://github.com/llvm/llvm-project/commit/ff23856c1c0cc4a8737e7338b084297e6877e910
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2023-06-20 (Tue, 20 Jun 2023)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/test/CodeGen/PowerPC/vec-zext-abdu.ll

  Log Message:
  -----------
  [DAG] Fold (abds x, y) -> (abdu x, y) iff both args are known positive

This is a generic DAG combine version of D151055 which recognizes when a signed ABDS can be safely replaced with a unsigned ABDU instruction if it is legal.

Alive2: https://alive2.llvm.org/ce/z/pb5BjG

Differential Revision: https://reviews.llvm.org/D153328