[all-commits] [llvm/llvm-project] 8afb2a: [SLP]Keep splat subtree load roots in memory order

[Alexey Bataev via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 8afb2a08d8b8d429ecd290e1052a9ca2fd2ed701
      https://github.com/llvm/llvm-project/commit/8afb2a08d8b8d429ecd290e1052a9ca2fd2ed701
  Author: Alexey Bataev <a.bataev at outlook.com>
  Date:   2026-09-22 (Tue, 22 Sep 2026)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
    M llvm/test/Transforms/SLPVectorizer/AArch64/splat-gather-subtree-root-order.ll

  Log Message:
  -----------
  [SLP]Keep splat subtree load roots in memory order

The roots have no users and the gathers reuse their lanes by value, but
the group or reordering-pass order added a reorder shuffle and non-free
extracts, so the profitable vector load was dropped.

Fixes the perf regression from #221717.

Reviewers: 

Pull Request: https://github.com/llvm/llvm-project/pull/225527



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