[all-commits] [llvm/llvm-project] 4fc417: [DAGCombiner] `convertBuildVecZextToBuildVecWithZe...

[Roman Lebedev via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 4fc417ec376cbd9646cbfd4f4c4659b4202f328e
      https://github.com/llvm/llvm-project/commit/4fc417ec376cbd9646cbfd4f4c4659b4202f328e
  Author: Roman Lebedev <lebedev.ri at gmail.com>
  Date:   2023-01-02 (Mon, 02 Jan 2023)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/test/CodeGen/AArch64/build-vector-extract.ll
    M llvm/test/CodeGen/X86/buildvec-insertvec.ll

  Log Message:
  -----------
  [DAGCombiner] `convertBuildVecZextToBuildVecWithZeros()`: rework split factor calculation

The original computation was both making assumptions that do not hold
in practice, and being overly pessimistic. We should just check
every possible split factor, and pick the best one.

Fixes https://github.com/llvm/llvm-project/issues/59781