[PATCH] D108136: [LoopVectorize] Permit vectorisation of more select(cmp(), X, Y) reduction patterns

[David Sherwood via Phabricator via llvm-commits]

david-arm updated this revision to Diff 377109.
david-arm added a comment.

- Fixed a buildbot sanitiser issue that occurred after merging the patch. The issue was that the input to the `select` instruction came from the induction PHI, and the output fed into the reduction PHI. Therefore, there wasn't a complete circular dependency and we shouldn't have vectorised.
- I have added the original reduction PHI as a parameter to `isSelectCmpPattern` so that we can ensure the input matches the reduction PHI node. This is now defended by the negative test `select_i32_from_icmp_non_redux_phi`
- I also added a new test called `select_i32_from_icmp_same_inputs ` to ensure we don't vectorise when both the icmp and the select use the same PHI node.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D108136/new/

https://reviews.llvm.org/D108136

Files:
  llvm/include/llvm/Analysis/IVDescriptors.h
  llvm/include/llvm/Transforms/Utils/LoopUtils.h
  llvm/lib/Analysis/IVDescriptors.cpp
  llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
  llvm/lib/Transforms/Utils/LoopUtils.cpp
  llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
  llvm/lib/Transforms/Vectorize/VPlan.cpp
  llvm/test/Transforms/LoopVectorize/AArch64/sve-select-cmp.ll
  llvm/test/Transforms/LoopVectorize/scalable-reduction-inloop.ll
  llvm/test/Transforms/LoopVectorize/select-cmp-predicated.ll
  llvm/test/Transforms/LoopVectorize/select-cmp.ll

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