TableGen: Use StringRef instead of const std::string& for parameters

This avoid an extra construction of a std::string (and a heap
allocation) when the caller only has a StringRef but no std::string at
hand.

llvm-svn: 288610
diff --git a/llvm/lib/TableGen/TGParser.cpp b/llvm/lib/TableGen/TGParser.cpp
index ff5c96b..3d0e487 100644
--- a/llvm/lib/TableGen/TGParser.cpp
+++ b/llvm/lib/TableGen/TGParser.cpp
@@ -715,8 +715,7 @@
 
 /// ParseIDValue - This is just like ParseIDValue above, but it assumes the ID
 /// has already been read.
-Init *TGParser::ParseIDValue(Record *CurRec,
-                             const std::string &Name, SMLoc NameLoc,
+Init *TGParser::ParseIDValue(Record *CurRec, StringRef Name, SMLoc NameLoc,
                              IDParseMode Mode) {
   if (CurRec) {
     if (const RecordVal *RV = CurRec->getValue(Name))