[all-commits] [llvm/llvm-project] f73ed3: [X86] lowerShuffleAsBroadcast - use isShuffleEquiv...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: f73ed3d4346c37292fbee99361a904e371d1d9eb
      https://github.com/llvm/llvm-project/commit/f73ed3d4346c37292fbee99361a904e371d1d9eb
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2025-02-12 (Wed, 12 Feb 2025)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/any_extend_vector_inreg_of_broadcast.ll
    M llvm/test/CodeGen/X86/any_extend_vector_inreg_of_broadcast_from_memory.ll
    M llvm/test/CodeGen/X86/avx512fp16-mov.ll
    M llvm/test/CodeGen/X86/copy-low-subvec-elt-to-high-subvec-elt.ll
    M llvm/test/CodeGen/X86/expand-vp-cast-intrinsics.ll
    M llvm/test/CodeGen/X86/matrix-multiply.ll
    M llvm/test/CodeGen/X86/pr51615.ll
    M llvm/test/CodeGen/X86/vector-half-conversions.ll
    M llvm/test/CodeGen/X86/vector-shuffle-128-v4.ll
    M llvm/test/CodeGen/X86/vector-shuffle-256-v16.ll
    M llvm/test/CodeGen/X86/zero_extend_vector_inreg_of_broadcast.ll
    M llvm/test/CodeGen/X86/zero_extend_vector_inreg_of_broadcast_from_memory.ll

  Log Message:
  -----------
  [X86] lowerShuffleAsBroadcast - use isShuffleEquivalent to search for a hidden broadcast pattern (#126517)

lowerShuffleAsBroadcast only matches a known-splat shuffle mask, but we
can use the isShuffleEquivalent/IsElementEquivalent helpers to attempt
to find a hidden broadcast-able shuffle pattern.

This requires an extension to IsElementEquivalent to peek through
bitcasts to match against wider shuffles - these typically appear during
shuffle lowering where we've widened a preceding shuffle, often to a
vector concatenation etc.

Amazingly I hit this while yak shaving #126033 .......



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