Fix use after free through StringRef.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@130828 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index bf73ca2..f2b685b 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -643,8 +643,9 @@
   CmdArgs.push_back("-target-abi");
   CmdArgs.push_back(ABIName);
 
+  std::string MArch;
   if (const Arg *A = Args.getLastArg(options::OPT_march_EQ)) {
-    llvm::StringRef MArch = A->getValue(Args);
+    MArch = A->getValue(Args);
     CmdArgs.push_back("-target-cpu");
 
     if ((MArch == "r2000") || (MArch == "r3000"))
@@ -652,7 +653,7 @@
     else if (MArch == "r6000")
       CmdArgs.push_back("mips2");
     else
-      CmdArgs.push_back(MArch.str().c_str());
+      CmdArgs.push_back(MArch.c_str());
   }
 
   // Select the float ABI as determined by -msoft-float, -mhard-float, and