1 files changed, 5 insertions, 2 deletions
diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index 6dcde958f0e..b031f905eba 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -2288,9 +2288,12 @@ bool GVN::performScalarPRE(Instruction *CurInst) {
       PHINode::Create(CurInst->getType(), predMap.size(),
                       CurInst->getName() + ".pre-phi", &CurrentBlock->front());
   for (unsigned i = 0, e = predMap.size(); i != e; ++i) {
-    if (Value *V = predMap[i].first)
+    if (Value *V = predMap[i].first) {
+      // If we use an existing value in this phi, we have to patch the original
+      // value because the phi will be used to replace a later value.
+      patchReplacementInstruction(CurInst, V);
       Phi->addIncoming(V, predMap[i].second);
-    else
+    } else
       Phi->addIncoming(PREInstr, PREPred);
   }