Use StringRef instead of std::string

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194601 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/LoopUnroll.cpp b/lib/Transforms/Utils/LoopUnroll.cpp
index 0b679fe..9955bfd 100644
--- a/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/lib/Transforms/Utils/LoopUnroll.cpp
@@ -90,7 +90,7 @@
   // Move all definitions in the successor to the predecessor...
   OnlyPred->getInstList().splice(OnlyPred->end(), BB->getInstList());
 
-  std::string OldName = BB->getName();
+  StringRef OldName = BB->getName();
 
   // Erase basic block from the function...