[all-commits] [llvm/llvm-project] 8d29d0: [VPlan] Run narrowInterleaveGroups during general ...

[Florian Hahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 8d29d09309654541fb2861524276ada6a3ebf84c
      https://github.com/llvm/llvm-project/commit/8d29d09309654541fb2861524276ada6a3ebf84c
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2025-10-21 (Tue, 21 Oct 2025)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    M llvm/lib/Transforms/Vectorize/VPlan.cpp
    M llvm/lib/Transforms/Vectorize/VPlan.h
    M llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
    M llvm/lib/Transforms/Vectorize/VPlanTransforms.h
    M llvm/test/Transforms/LoopVectorize/AArch64/transform-narrow-interleave-to-widen-memory-constant-ops.ll
    M llvm/test/Transforms/LoopVectorize/AArch64/transform-narrow-interleave-to-widen-memory-cost.ll
    M llvm/test/Transforms/LoopVectorize/AArch64/transform-narrow-interleave-to-widen-memory-remove-loop-region.ll
    M llvm/test/Transforms/LoopVectorize/AArch64/transform-narrow-interleave-to-widen-memory-scalable.ll
    M llvm/test/Transforms/LoopVectorize/AArch64/transform-narrow-interleave-to-widen-memory-unroll.ll
    M llvm/test/Transforms/LoopVectorize/AArch64/transform-narrow-interleave-to-widen-memory.ll
    M llvm/test/Transforms/LoopVectorize/X86/transform-narrow-interleave-to-widen-memory.ll

  Log Message:
  -----------
  [VPlan] Run narrowInterleaveGroups during general VPlan optimizations. (#149706)

Move narrowInterleaveGroups to to general VPlan optimization stage.

To do so, narrowInterleaveGroups now has to find a suitable VF where all
interleave groups are consecutive and saturate the full vector width.

If such a VF is found, the original VPlan is split into 2:
 a) a new clone which contains all VFs of Plan, except VFToOptimize, and
 b) the original Plan with VFToOptimize as single VF.

The original Plan is then optimized. If a new copy for the other VFs has
been created, it is returned and the caller has to add it to the list of
candidate plans.

Together with https://github.com/llvm/llvm-project/pull/149702, this
allows to take the narrowed interleave groups into account when
computing costs to choose the best VF and interleave count.

One example where we currently miss interleaving/unrolling when
narrowing interleave groups is https://godbolt.org/z/Yz77zbacz

PR: https://github.com/llvm/llvm-project/pull/149706



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