Remove unused code, improve speed of Parser::CurrentToken (improvement seen in measurements and pro…

runtime/vm/parser.h

Index: runtime/vm/parser.h
===================================================================
--- runtime/vm/parser.h	(revision 36705)
+++ runtime/vm/parser.h	(working copy)
@@ -240,7 +240,17 @@
   }
 
   intptr_t TokenPos() const { return tokens_iterator_.CurrentPosition(); }
-  inline Token::Kind CurrentToken();
+
+  Token::Kind CurrentToken() {

[hausner, 2014/05/27 21:03:29]

The performance now depends even more on the whim of the compiler's inlining
magic. In most cases, we only call CurrentToken() once to determine what we are
parsing. In cases where the parser calls it repetitively without advancing, we
should cache it locally. Eg. in ParseStatement() or ParsePrimary().

+    if (token_kind_ == Token::kILLEGAL) {
+      ComputeCurrentToken();
+    }
+    CompilerStats::num_token_checks++;
+    return token_kind_;
+  }
+
+  void ComputeCurrentToken();
+
   Token::Kind LookaheadToken(int num_tokens);
   String* CurrentLiteral() const;
   RawDouble* CurrentDoubleLiteral() const;