[all-commits] [llvm/llvm-project] 2db59e: [LoopInterchange] Fix the vectorizable check for a...

[Ryotaro Kasuga via All-commits]

  Branch: refs/heads/users/kasuga-fj/loop-interchange-fix-profitable-vectorization
  Home:   https://github.com/llvm/llvm-project
  Commit: 2db59e8629d3640ec070eb906ac55a5e970176d1
      https://github.com/llvm/llvm-project/commit/2db59e8629d3640ec070eb906ac55a5e970176d1
  Author: Ryotaro Kasuga <kasuga.ryotaro at fujitsu.com>
  Date:   2025-03-27 (Thu, 27 Mar 2025)

  Changed paths:
    M llvm/lib/Transforms/Scalar/LoopInterchange.cpp
    M llvm/test/Transforms/LoopInterchange/profitability-vectorization-heuristic.ll

  Log Message:
  -----------
  [LoopInterchange] Fix the vectorizable check for a loop

In the profitability check for vectorization, the dependency matrix was
not handled correctly. This can result to make a wrong decision: It may
say "this loop can be vectorized" when in fact it cannot. The root cause
of this is that the check process early returns when it finds '=' or 'I'
in the dependency matrix. To make sure that we can actually vectorize
the loop, we need to check all the rows of the matrix. This patch fixes
the process of checking whether we can vectorize the loop or not. Now it
won't make a wrong decision for a loop that cannot be vectorized.

Related: #131130



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