[all-commits] [llvm/llvm-project] 705636: [SelectionDAG][RISCV] Move VP_REDUCE* legalization...

[Craig Topper via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 705636a1130551ab105aec95b909a35a0305fc9f
      https://github.com/llvm/llvm-project/commit/705636a1130551ab105aec95b909a35a0305fc9f
  Author: Craig Topper <craig.topper at sifive.com>
  Date:   2024-04-29 (Mon, 29 Apr 2024)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
    M llvm/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp
    M llvm/test/CodeGen/RISCV/rvv/fixed-vectors-reduction-int-vp.ll
    M llvm/test/CodeGen/RISCV/rvv/vreductions-int-vp.ll

  Log Message:
  -----------
  [SelectionDAG][RISCV] Move VP_REDUCE* legalization to LegalizeDAG.cpp. (#90522)

LegalizeVectorType is responsible for legalizing nodes that perform an
operation on each element may need to scalarize.

This is not true for nodes like VP_REDUCE.*, BUILD_VECTOR,
SHUFFLE_VECTOR, EXTRACT_SUBVECTOR, etc.

This patch drops any nodes with a scalar result from LegalizeVectorOps
and handles them in LegalizeDAG instead.

This required moving the reduction promotion to LegalizeDAG. I have
removed the support integer promotion as it was incorrect for integer
min/max reductions. Since it was untested, it was best to assert on it
until it was really needed.

There are a couple regressions that can be fixed with a small DAG
combine which I will do as a follow up.



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