Allow for the case where the name of the subprogram is "".

Fixes a self-host error.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143970 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -525,6 +525,7 @@ CompileUnit *DwarfDebug::constructCompileUnit(const MDNode *N) {
 }
 
 static bool isObjCClass(StringRef Name) {
+  if (Name == "") return false;
   return Name[0] == '+' || Name[0] == '-';
 }