[all-commits] [llvm/llvm-project] 26324b: [VPlan] Move FOR splice cost into VPInstruction::F...

[Luke Lau via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 26324bc1bf397453ce966f56a88245263f7beec5
      https://github.com/llvm/llvm-project/commit/26324bc1bf397453ce966f56a88245263f7beec5
  Author: Luke Lau <luke at igalia.com>
  Date:   2025-03-14 (Fri, 14 Mar 2025)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp
    M llvm/test/Transforms/LoopVectorize/RISCV/vplan-vp-intrinsics-fixed-order-recurrence.ll

  Log Message:
  -----------
  [VPlan] Move FOR splice cost into VPInstruction::FirstOrderRecurrenceSplice (#129645)

After #124093 we now support fixed-order recurrences with EVL tail
folding by replacing VPInstruction::FirstOrderRecurrenceSplice with a VP
splice intrinsic.

However the costing for the splice is currently done in
VPFirstOrderRecurrencePHIRecipe, so when we add the VP splice intrinsic
we end up costing it twice.

This fixes it by splitting out the cost for the splice into
FirstOrderRecurrenceSplice so that it's not duplicated when we replace
it.

We still have to keep the VF=1 checks in VPFirstOrderRecurrencePHIRecipe
since the splice might end up dead and discarded, e.g. in the test
@pr97452_scalable_vf1_for.



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