[PATCH] D88962: [SVE] Add support for scalable vectors in vectorize_width loop attribute

[David Sherwood via Phabricator via llvm-commits]

david-arm created this revision.
david-arm added reviewers: sdesmalen, ctetreau, paulwalker-arm, kmclaughlin.
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david-arm requested review of this revision.

In this patch I have added support for a new variant of the
vectorize_width loop attribute that essentially takes an ElementCount
instead of a vectorization factor. If a user wants to instruct the
compiler to vectorize a loop with scalable vectors they can now do
this as follows:

  br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !2
  ...
  !2 = !{!2, !3}
  !3 = !{!"llvm.loop.vectorize.width", !4}
  !4 = !{i32 8, i32 0}

where the ElementCount (!4 in the example above) has two parameters.
The first parameter is the vectorization factor and the second is the
scalable vector flag, where 0==fixed width and 1==scalable.

For backwards compatibility we still support using vectorize_width
with a single integer argument and in this case defaults to fixed width
vectorization.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D88962

Files:
  llvm/include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h
  llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
  llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
  llvm/test/Transforms/LoopVectorize/metadata-width.ll

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