[all-commits] [llvm/llvm-project] 3467e7: [SLP] Fix extract-cost scale for LCSSA-phi externa...

[Alexey Bataev via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 3467e7f9eb16b687bf79fe96b33a243542c9d701
      https://github.com/llvm/llvm-project/commit/3467e7f9eb16b687bf79fe96b33a243542c9d701
  Author: Alexey Bataev <a.bataev at outlook.com>
  Date:   2026-05-30 (Sat, 30 May 2026)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
    M llvm/test/Transforms/SLPVectorizer/AArch64/lcssa-phi-inner-loop-scale.ll

  Log Message:
  -----------
  [SLP] Fix extract-cost scale for LCSSA-phi external users in nested loops

getScaleToLoopIterations() used U->getParent() for all PHI-node external
users. For an LCSSA phi at an inner-loop exit still inside an outer loop,
this gave outer-loop scale instead of inner*outer scale. Because
ExtractCostCalculated deduplicates by scalar, only the first ExternalUser
determines the scale, making the cost order-dependent on use-list ordering
(and thus on .ll block ordering).

Reviewers: hiraditya, RKSimon, bababuck

Pull Request: https://github.com/llvm/llvm-project/pull/199954



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