[PATCH] D35391: [Dominators] Teach LoopDeletion to use the new incremental API

[Jakub Kuderski via Phabricator via llvm-commits]

kuhar updated this revision to Diff 108541.
kuhar edited the summary of this revision.
kuhar added a comment.

Zhendong and Qirun were able to generate a CFG that broke the previous update chained logic. It turns out, that it's not legal to chain a deletion and an insertion when there's irreducible control flow that appears in the temporarily deleted subtree. I added a regression test for that.

I think that this shows that the current incremental API is tricky to use when CFG and DomTree updates are not performed in lockstep, and we *really* need a proper batch update API.


https://reviews.llvm.org/D35391

Files:
  include/llvm/Support/GenericDomTree.h
  lib/Transforms/Scalar/LoopDeletion.cpp
  test/Transforms/LoopDeletion/2017-07-11-incremental-dt.ll
  unittests/IR/DominatorTreeTest.cpp

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