[PATCH] D101305: [LoopInterchange] Fix legality for triangular loops

[Congzhe Cao via Phabricator via llvm-commits]

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This is a bug fix in legality check.

When we encounter triangular loops such as the following form:

  for (int i = 0; i < m; i++)
    for (int j = 0; j < i; j++), or
  
  for (int i = 0; i < m; i++)
    for (int j = 0; j*i < n; j++),

we should not perform interchange since the number of executions of the loop body 
will be different before and after interchange, resulting in incorrect results.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D101305

Files:
  llvm/lib/Transforms/Scalar/LoopInterchange.cpp
  llvm/test/Transforms/LoopInterchange/inner-indvar-depend-on-outer-indvar.ll

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