Preserve dominance frontier while trivially unswitching loop.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52438 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp
index e0fb4c6..955622e 100644
--- a/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -610,6 +610,23 @@
DT->changeImmediateDominator(NewExit, OrigPH);
DT->changeImmediateDominator(NewPH, OrigPH);
}
+
+ if (DF) {
+ // NewExit is now part of NewPH and Loop Header's dominance
+ // frontier.
+ DominanceFrontier::iterator DFI = DF->find(NewPH);
+ if (DFI != DF->end())
+ DF->addToFrontier(DFI, NewExit);
+ DFI = DF->find(L->getHeader());
+ DF->addToFrontier(DFI, NewExit);
+
+ // ExitBlock does not have successors then NewExit is part of
+ // its dominance frontier.
+ if (succ_begin(ExitBlock) == succ_end(ExitBlock)) {
+ DFI = DF->find(ExitBlock);
+ DF->addToFrontier(DFI, NewExit);
+ }
+ }
LPM->deleteSimpleAnalysisValue(OrigPH->getTerminator(), L);
OrigPH->getTerminator()->eraseFromParent();