1 files changed, 12 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index fbae547..b203259 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1089,6 +1089,18 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
     }
   }
 
+  // We cannot fold the block if it's a branch to an already present callbr
+  // successor because that creates duplicate successors.
+  for (BasicBlock *PredBB : predecessors(BB)) {
+    if (auto *CBI = dyn_cast<CallBrInst>(PredBB->getTerminator())) {
+      if (Succ == CBI->getDefaultDest())
+        return false;
+      for (unsigned i = 0, e = CBI->getNumIndirectDests(); i != e; ++i)
+        if (Succ == CBI->getIndirectDest(i))
+          return false;
+    }
+  }
+
   LLVM_DEBUG(dbgs() << "Killing Trivial BB: \n" << *BB);
 
   SmallVector<DominatorTree::UpdateType, 32> Updates;