[PATCH] D69009: [IndVars] Eliminate loop exits with equivalent exit counts

[Philip Reames via Phabricator via llvm-commits]

reames created this revision.
reames added reviewers: nikic, ebrevnov, apilipenko.
Herald added subscribers: mgrang, bollu, mcrosier.
Herald added a project: LLVM.

We can end up with two loop exits whose exit counts are equivalent, but whose textual representation is different and non-obvious.  For the sub-case where we have a series of exits which dominate one another (common), eliminate any exits which would iterate *after* a previous exit on the exiting iteration.

As noted in the TODO being removed, I'd always thought this was a good idea, but I've now seen this in a real workload as well.  This needs to be rebased on D68956 <https://reviews.llvm.org/D68956> as both need the same dominance order check.


Repository:
  rL LLVM

https://reviews.llvm.org/D69009

Files:
  lib/Transforms/Scalar/IndVarSimplify.cpp
  test/Transforms/IndVarSimplify/eliminate-exit.ll

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