diff --git a/lib/Transforms/Vectorize/SLPVectorizer.cpp b/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 60749b4b9f6..0313e9834b6 100644
--- a/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -278,7 +278,7 @@ private:
 
   /// \returns the pointer to the vectorized value if \p VL is already
   /// vectorized, or NULL. They may happen in cycles.
-  Value *alreadyVectorized(ArrayRef<Value *> VL);
+  Value *alreadyVectorized(ArrayRef<Value *> VL) const;
 
   /// \brief Take the pointer operand from the Load/Store instruction.
   /// \returns NULL if this is not a valid Load/Store instruction.
@@ -319,7 +319,7 @@ private:
     NeedToGather(0) {}
 
     /// \returns true if the scalars in VL are equal to this entry.
-    bool isSame(ArrayRef<Value *> VL) {
+    bool isSame(ArrayRef<Value *> VL) const {
       assert(VL.size() == Scalars.size() && "Invalid size");
       for (int i = 0, e = VL.size(); i != e; ++i)
         if (VL[i] != Scalars[i])
@@ -1098,10 +1098,12 @@ Value *BoUpSLP::Gather(ArrayRef<Value *> VL, VectorType *Ty) {
   return Vec;
 }
 
-Value *BoUpSLP::alreadyVectorized(ArrayRef<Value *> VL) {
-  if (ScalarToTreeEntry.count(VL[0])) {
-    int Idx = ScalarToTreeEntry[VL[0]];
-    TreeEntry *En = &VectorizableTree[Idx];
+Value *BoUpSLP::alreadyVectorized(ArrayRef<Value *> VL) const {
+  SmallDenseMap<Value*, int>::const_iterator Entry
+    = ScalarToTreeEntry.find(VL[0]);
+  if (Entry != ScalarToTreeEntry.end()) {
+    int Idx = Entry->second;
+    const TreeEntry *En = &VectorizableTree[Idx];
     if (En->isSame(VL) && En->VectorizedValue)
       return En->VectorizedValue;
   }