[PATCH] D98475: [LoopInterchange] Fix transformation bugs in loop interchange

[Congzhe Cao via Phabricator via llvm-commits]

congzhe created this revision.
congzhe added reviewers: Whitney, fhahn.
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After loop interchange, the outer loop header should not jump to
the `LoopExit`. Note that the outer loop becomes the inner loop
after interchange. If we branch to `LoopExit` then after interchange
we would jump directly from the (new) inner loop header to `LoopExit`
without executing the rest of outer loop.

This patch modifies adjustLoopBranches() such that the old outer
loop header (which becomes the new inner loop header) jumps to the
old inner loop latch, which becomes the new outer loop latch after
interchange.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D98475

Files:
  llvm/lib/Transforms/Scalar/LoopInterchange.cpp
  llvm/test/Transforms/LoopInterchange/lcssa-preheader.ll
  llvm/test/Transforms/LoopInterchange/outer-header-jump-to-inner-latch.ll

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