[all-commits] [llvm/llvm-project] 0fb198: [X86] Remove combineShuffleOfConcatUndef fold (#14...

[Simon Pilgrim via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 0fb198e132eff36281a20698588d815c3c30f991
      https://github.com/llvm/llvm-project/commit/0fb198e132eff36281a20698588d815c3c30f991
  Author: Simon Pilgrim <llvm-dev at redking.me.uk>
  Date:   2025-06-17 (Tue, 17 Jun 2025)

  Changed paths:
    M llvm/lib/Target/X86/X86ISelLowering.cpp
    M llvm/test/CodeGen/X86/horizontal-sum.ll

  Log Message:
  -----------
  [X86] Remove combineShuffleOfConcatUndef fold (#144524)

We can now let a mixture of combineConcatVectorOps and target shuffle combining handle this instead of creating ISD::CONCAT_VECTORS nodes and hoping they will merge properly.

In the horizontal-sum.ll test changes we were creating a ISD::CONCAT_VECTORS node that was being split shortly after, but not before causing issues with HADD folding due to additional uses.



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