Add a bit to IdentifierInfo that acts as a simple predicate which
tells us whether Preprocessor::HandleIdentifier needs to be called.
Because this method is only rarely needed, this saves a call and a
bunch of random checks.  This drops the time in HandleIdentifier 
from 3.52ms to .98ms on cocoa.h on my machine.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@62675 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Lex/Lexer.cpp b/lib/Lex/Lexer.cpp
index 19b3121..f7937d5 100644
--- a/lib/Lex/Lexer.cpp
+++ b/lib/Lex/Lexer.cpp
@@ -560,7 +560,9 @@
     
     // Finally, now that we know we have an identifier, pass this off to the
     // preprocessor, which may macro expand it or something.
-    return PP->HandleIdentifier(Result);
+    if (Result.getIdentifierInfo()->isHandleIdentifierCase())
+      PP->HandleIdentifier(Result);
+    return;
   }
   
   // Otherwise, $,\,? in identifier found.  Enter slower path.