[PATCH] D105199: [LoopVectorize] Fix scalable vector crash in VPReplicateRecipe::execute

[David Sherwood via Phabricator via llvm-commits]

david-arm created this revision.
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When trying to vectorise certain loops using scalable vectors we try to
use the replicate recipe even for non-uniform cases. The recipe does
not handle scalable vectors correctly because it tries to scalarise
the vector instruction by generating a scalar instance for each lane
and packing them into a vector. We don't know the number of lanes at
runtime so this is not an option.

I've decided to create a new scalable replicate recipe instead called
VPScalableReplicate, which also calls a new overloaded version of
scalarizeInstruction that generates a whole vector part in one go,
instead of generating N scalar instances for N lanes. The new version
of scalarizeInstruction is based on the original version, and currently
only supports certain cases, such as GEP instructions, or instructions
with loop-invariant operands.

Tests have been added here:

  Transforms/LoopVectorize/AArch64/sve-vpreplicate.ll


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D105199

Files:
  llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
  llvm/lib/Transforms/Vectorize/VPlan.cpp
  llvm/lib/Transforms/Vectorize/VPlan.h
  llvm/lib/Transforms/Vectorize/VPlanValue.h
  llvm/test/Transforms/LoopVectorize/AArch64/sve-vpreplicate.ll

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