[PATCH] D93725: [LV] Relax assumption that LCSSA implies single entry

[Philip Reames via Phabricator via llvm-commits]

reames created this revision.
reames added reviewers: Ayal, fhahn.
Herald added subscribers: dantrushin, bollu, hiraditya, mcrosier.
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This relates to the ongoing effort to support vectorization of multiple exit loops (see D93317 <https://reviews.llvm.org/D93317>).

The previous code assumed that LCSSA phis were always single entry before the vectorizer ran.  This was correct, but only because the vectorizer allowed only a single exiting edge.  There's nothing in the definition of LCSSA which requires single entry phis.

A common case where this comes up is with a loop with multiple exiting blocks which all reach a common exit block.  (e.g. see the test updates)


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D93725

Files:
  llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
  llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
  llvm/test/Transforms/LoopVectorize/loop-form.ll

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