[PATCH] D117307: [LoopVectorize] Only check for ordered reductions if the op chain was found

[Kerry McLaughlin via Phabricator via llvm-commits]

kmclaughlin created this revision.
kmclaughlin added reviewers: david-arm, dmgreen, sdesmalen.
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As we cannot vectorise strict reductions if the reduction is not also
classified as in-loop, we should not call checkOrderedReductions
if getReductionOpChain was not able to find the chain.

This removes the additional check on the number of uses of `Exit` in
checkOrderedReductions introduced in D114002 <https://reviews.llvm.org/D114002>, added to fix an issue
where IsOrdered was true but the reduction op chain was not found.

The `!LoopExitInstr->hasNUses(2)` restriction has also been removed from
getReductionOpChain.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D117307

Files:
  llvm/include/llvm/Analysis/IVDescriptors.h
  llvm/lib/Analysis/IVDescriptors.cpp
  llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

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