Improve code for !identical(a, b):

runtime/vm/token.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_TOKEN_H_
 #define VM_TOKEN_H_
 
 #include "platform/assert.h"
 
 namespace dart {
@@ skipping 272 matching lines @@
     return ((tok == Token::kINTEGER) ||
             (tok == Token::kSTRING) ||
             (tok == Token::kINTERPOL_VAR) ||
             (tok == Token::kERROR) ||
             (tok == Token::kDOUBLE));
   }
 
   static bool IsBinaryOperator(Token::Kind token);
   static bool IsPrefixOperator(Token::Kind token);
 
+  // For a comparison operation return an operation for the negated comparison:
+  // !(a (op) b) === a (op') b
+  static Token::Kind NegateComparison(Token::Kind op) {
+    switch (op) {
+      case Token::kEQ: return Token::kNE;
+      case Token::kNE: return Token::kEQ;
+      case Token::kLT: return Token::kGTE;
+      case Token::kGT: return Token::kLTE;
+      case Token::kLTE: return Token::kGT;
+      case Token::kGTE: return Token::kLT;
+      case Token::kEQ_STRICT: return Token::kNE_STRICT;
+      case Token::kNE_STRICT: return Token::kEQ_STRICT;
+      default:
+        UNREACHABLE();
+        return Token::kILLEGAL;
+    }
+  }
+
  private:
   static const char* name_[];
   static const char* tok_str_[];
   static const uint8_t precedence_[];
   static const Attribute attributes_[];
 };
 
 
 }  // namespace dart
 
 #endif  // VM_TOKEN_H_