[all-commits] [llvm/llvm-project] a7b7d2: [LoopInterchange] Check lcssa phis in the inner la...

[CongzheUalberta via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: a7b7d22d6ead13c44a8ff55ad119179fbb3d1686
      https://github.com/llvm/llvm-project/commit/a7b7d22d6ead13c44a8ff55ad119179fbb3d1686
  Author: Congzhe Cao <congzhe.cao at huawei.com>
  Date:   2021-07-16 (Fri, 16 Jul 2021)

  Changed paths:
    M llvm/lib/Transforms/Scalar/LoopInterchange.cpp
    A llvm/test/Transforms/LoopInterchange/innermost-latch-uses-values-in-middle-header.ll

  Log Message:
  -----------
  [LoopInterchange] Check lcssa phis in the inner latch in scenarios of multi-level nested loops

We already know that we need to check whether lcssa
phis are supported in inner loop exit block or in
outer loop exit block, and we have logic to check
them already. Presumably the inner loop latch does
not have lcssa phis and there is no code that deals
with lcssa phis in the inner loop latch. However,
that assumption is not true, when we have loops
with more than two-level nesting. This patch adds
checks for lcssa phis in the inner latch.

Reviewed By: Whitney

Differential Revision: https://reviews.llvm.org/D102300