Avoid duplicated map lookups. No functionality change intended.

llvm-svn: 273030
diff --git a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
index 21c0c9d..fe15d17 100644
--- a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -2616,9 +2616,8 @@
   // We may have base pointers which are now live that weren't before.  We need
   // to update the PointerToBase structure to reflect this.
   for (auto V : Updated)
-    if (!Info.PointerToBase.count(V)) {
+    if (Info.PointerToBase.insert(std::make_pair(V, V)).second) {
       assert(Bases.count(V) && "can't find base for unexpected live value");
-      Info.PointerToBase[V] = V;
       continue;
     }