[all-commits] [llvm/llvm-project] 0f2ac4: [LoopInterchange] Add tests for the vectorization ...

[Ryotaro Kasuga via All-commits]

  Branch: refs/heads/users/kasuga-fj/loop-interchange-vectorzation-test
  Home:   https://github.com/llvm/llvm-project
  Commit: 0f2ac45dd84ead993f832d33c42c986b565fb406
      https://github.com/llvm/llvm-project/commit/0f2ac45dd84ead993f832d33c42c986b565fb406
  Author: Ryotaro Kasuga <kasuga.ryotaro at fujitsu.com>
  Date:   2025-04-02 (Wed, 02 Apr 2025)

  Changed paths:
    A llvm/test/Transforms/LoopInterchange/profitability-vectorization-heuristic.ll

  Log Message:
  -----------
  [LoopInterchange] Add tests for the vectorization profitability (NFC)

There is a problem with the current profitability check for
vectorization in LoopInterchange. There are both false positives and
false negatives. The former means that the heuristic may say that "an
exchange is necessary to vectorize the innermost loop" even though it's
already possible. The latter means that the heuristic may miss a case
where an exchange is necessary to vectorize the innermost loop. Note
that this is not a dependency analysis problem.  These problems can
occur even if the analysis is accurate (no overestimation).

This patch adds tests to clarify the cases that should be fixed. The
root cause of these cases is that the heuristic doesn't handle the
direction of a dependency correctly.



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