[all-commits] [llvm/llvm-project] 6766ee: [VPlan] Create header phi recipes after initial sc...

[Florian Hahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6766eea39e4b362066f1e2678a09a78ad98c2183
      https://github.com/llvm/llvm-project/commit/6766eea39e4b362066f1e2678a09a78ad98c2183
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2026-06-10 (Wed, 10 Jun 2026)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    M llvm/lib/Transforms/Vectorize/VPlanConstruction.cpp
    M llvm/test/Transforms/LoopVectorize/VPlan/X86/scalarize-wide-load-for-address-use.ll
    M llvm/test/Transforms/LoopVectorize/VPlan/constant-fold.ll
    M llvm/test/Transforms/LoopVectorize/VPlan/for-phi-ordering.ll
    M llvm/test/Transforms/LoopVectorize/VPlan/vplan-print-after-all.ll

  Log Message:
  -----------
  [VPlan] Create header phi recipes after initial scalar optimizations. (#200920)

Move createHeaderPhiRecipes after initial scalar transformations.

Header phi creation effectively is the first step of the widening
process. Running scalar opimizations before it can clean up dead header
phis and also also results in a cleaned up scalar VPlan that can be used
to compute the cost of the scalar loop accurately
(https://github.com/llvm/llvm-project/pull/196845).

Now that creating header phis happens after replaceSymbolicStrides we
are looking up the stride from the VPlan directly if possible.

PR: https://github.com/llvm/llvm-project/pull/200920



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