[PATCH] D91682: [LoopInterchange] Fix the checking of tightly nested loop

[Geng via Phabricator via llvm-commits]

geng created this revision.
geng added reviewers: fhahn, Whitney.
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In the loop interchange pass, when checking if the loops are tightly(perfectly) nested,  the checking of the latches are missed. This patch is supposed to use the LoopNestAnalysis to check if the loops are perfectly nested. In order to apply the LoopNestAnalysis on LoopInterchange, we did following modifications:

1. Remove the restriction that if we can not get the outer loop bound, then the loops are not perfectly nested.
2. Add the case when outer header branches to inner preheader which do not violate the perfectly nested property.
3. Add the case when InnerLoopExit equals to the OuterLoopLatch, which do not violate the perfectly nested property.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D91682

Files:
  llvm/lib/Analysis/LoopNestAnalysis.cpp
  llvm/lib/Transforms/Scalar/LoopInterchange.cpp
  llvm/test/Transforms/LoopInterchange/perfectly-nested.ll

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