[all-commits] [llvm/llvm-project] 0cafda: DAG: Avoid breaking legal vector_shuffle with mult...

[Matt Arsenault via All-commits]

  Branch: refs/heads/users/arsenm/dag/avoid-breaking-multi-use-legal-shuffle-after-legalize
  Home:   https://github.com/llvm/llvm-project
  Commit: 0cafdabfc2de09242b4b555925861ec35d8af392
      https://github.com/llvm/llvm-project/commit/0cafdabfc2de09242b4b555925861ec35d8af392
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2025-01-22 (Wed, 22 Jan 2025)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4f32.v2f32.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4f32.v3f32.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4f32.v4f32.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4i32.v2i32.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4i32.v3i32.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4i32.v4i32.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4p3.v2p3.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4p3.v3p3.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4p3.v4p3.ll

  Log Message:
  -----------
  DAG: Avoid breaking legal vector_shuffle with multiple uses

Previously this combine would undo AMDGPU's new custom legalization of
wide vector shuffles into 2 element pieces. The comment also
states that this combine is only done before legalization,
but the case with a build_vector source was unconditional.

We probably don't want to do this if the multiple uses are full
scalarization of the vector, but this seems to work well enough.
Scalarizing extracts should have folded out pre-legalize.


  Commit: efabfc61b4194bee6c8a019f3399c9c23ad2befb
      https://github.com/llvm/llvm-project/commit/efabfc61b4194bee6c8a019f3399c9c23ad2befb
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2025-01-22 (Wed, 22 Jan 2025)

  Changed paths:
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4f32.v2f32.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4f32.v3f32.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4f32.v4f32.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4i32.v2i32.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4i32.v3i32.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4i32.v4i32.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4p3.v2p3.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4p3.v3p3.ll
    M llvm/test/CodeGen/AMDGPU/shufflevector.v4p3.v4p3.ll

  Log Message:
  -----------
  Update tests for base commit changes


Compare: https://github.com/llvm/llvm-project/compare/625ee25e8a05...efabfc61b419

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