Reserve the size we'll need in advance.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52763 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 3c4e6bc..39a91df 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -1004,6 +1004,7 @@
   
   // Traverse the constant array from StartIdx (derived above) which is
   // the place the GEP refers to in the array.
+  Str.reserve(NumElts);
   for (unsigned i = StartIdx; i < NumElts; ++i) {
     Constant *Elt = Array->getOperand(i);
     ConstantInt *CI = dyn_cast<ConstantInt>(Elt);