From 9ee942f4814dd5a12cc37eb0be9e1734c4f0cfe4 Mon Sep 17 00:00:00 2001 From: Balaram Makam Date: Thu, 26 Oct 2017 15:04:53 +0000 Subject: Reapply r316582 [Local] Fix a bug in the domtree update logic for MergeBasicBlockIntoOnlyPred. Summary: This reverts r316612 to reapply r316582. The buildbot failure was unrelated to this commit. Reviewers: Subscribers: llvm-svn: 316669 --- llvm/lib/Transforms/Utils/Local.cpp | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'llvm/lib/Transforms/Utils/Local.cpp') diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp index fd3367710f3..8c643c93ec4 100644 --- a/llvm/lib/Transforms/Utils/Local.cpp +++ b/llvm/lib/Transforms/Utils/Local.cpp @@ -649,9 +649,13 @@ void llvm::MergeBasicBlockIntoOnlyPred(BasicBlock *DestBB, DominatorTree *DT) { DestBB->moveAfter(PredBB); if (DT) { - BasicBlock *PredBBIDom = DT->getNode(PredBB)->getIDom()->getBlock(); - DT->changeImmediateDominator(DestBB, PredBBIDom); - DT->eraseNode(PredBB); + // For some irreducible CFG we end up having forward-unreachable blocks + // so check if getNode returns a valid node before updating the domtree. + if (DomTreeNode *DTN = DT->getNode(PredBB)) { + BasicBlock *PredBBIDom = DTN->getIDom()->getBlock(); + DT->changeImmediateDominator(DestBB, PredBBIDom); + DT->eraseNode(PredBB); + } } // Nuke BB. PredBB->eraseFromParent(); -- cgit v1.2.3