diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -16148,7 +16148,7 @@
           unsigned Elts = (i + 1) * NumMemElts;
           EVT Ty =
               EVT::getVectorVT(*DAG.getContext(), MemVT.getScalarType(), Elts);
-          bool IsFast;
+          bool IsFast = false;
 
           // Break early when size is too large to be legal.
           if (Ty.getSizeInBits() > MaximumLegalStoreInBits)
@@ -16284,7 +16284,8 @@
         if (StoreTy.getSizeInBits() > MaximumLegalStoreInBits)
           break;
 
-        bool IsFastSt, IsFastLd;
+        bool IsFastSt = false;
+        bool IsFastLd = false;
         if (TLI.isTypeLegal(StoreTy) &&
             TLI.canMergeStoresTo(FirstStoreAS, StoreTy, DAG) &&
             TLI.allowsMemoryAccess(Context, DL, StoreTy,