[PATCH] D57316: [LoopSimplifyCFG] Fix DT update strategy

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev created this revision.
mkazantsev added reviewers: anna, asbirlea, skatkov, reames.

DT Updater sometimes does not update nodes in unreachable subtrees
(unreachable in terms of DomTree). When we use eager update strategy,
we can end up not making some updates that need to be made because
previous update break the tree.

This patch fixes this behavior by using lazy update strategy in DTU. We only
make all updates in the end (and when we need to form LCSSA after dead
exit fixup and before folding).


https://reviews.llvm.org/D57316

Files:
  lib/Transforms/Scalar/LoopSimplifyCFG.cpp
  test/Transforms/LoopSimplifyCFG/constant-fold-branch.ll

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