Clarify that DIEString does not keep a copy of the string.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90318 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index dcb5900..da2b9c3 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -330,8 +330,8 @@
   Die->addValue(Attribute, Form, Value);
 }
 
-/// addString - Add a string attribute data and value.
-///
+/// addString - Add a string attribute data and value. DIEString only
+/// keeps string reference. 
 void DwarfDebug::addString(DIE *Die, unsigned Attribute, unsigned Form,
                            const StringRef String) {
   DIEValue *Value = new DIEString(String);