Make identical(a,b) a compile-time constant in dart2js.

lib/compiler/implementation/compile_time_constants.dart

 // 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.
 
 /**
  * The [ConstantHandler] keeps track of compile-time constants,
  * initializations of global and static fields, and default values of
  * optional parameters.
  */
 class ConstantHandler extends CompilerTask {
@@ skipping 371 matching lines @@
       StringConstant partString = evaluate(part.string);
       if (partString == null) return null;
       accumulator = new DartString.concat(accumulator, partString.value);
     };
     return constantSystem.createString(accumulator, node);
   }
 
   // TODO(floitsch): provide better error-messages.
   Constant visitSend(Send send) {
     Element element = elements[send];
-    if (Elements.isStaticOrTopLevelField(element)) {
-      Constant result;
-      if (element.modifiers !== null) {
-        if (element.modifiers.isConst()) {
-          result = compiler.compileConstant(element);
-        } else if (element.modifiers.isFinal() && !isEvaluatingConstant) {
-          result = compiler.compileVariable(element);
+    if (send.isPropertyAccess) {
+      if (Elements.isStaticOrTopLevelFunction(element)) {
+        compiler.codegenWorld.staticFunctionsNeedingGetter.add(element);
+        Constant constant = new FunctionConstant(element);
+        compiler.constantHandler.registerCompileTimeConstant(constant);
+        compiler.enqueuer.codegen.registerStaticUse(element);
+        return constant;
+      } else if (Elements.isStaticOrTopLevelField(element)) {
+        Constant result;
+        if (element.modifiers !== null) {
+          if (element.modifiers.isConst()) {
+            result = compiler.compileConstant(element);
+          } else if (element.modifiers.isFinal() && !isEvaluatingConstant) {
+            result = compiler.compileVariable(element);
+          }
         }
+        if (result !== null) return result;
       }
-      if (result == null) return signalNotCompileTimeConstant(send);
-      return result;
-    } else if (Elements.isStaticOrTopLevelFunction(element)
-               && send.isPropertyAccess) {
-      compiler.codegenWorld.staticFunctionsNeedingGetter.add(element);
-      Constant constant = new FunctionConstant(element);
-      compiler.constantHandler.registerCompileTimeConstant(constant);
-      compiler.enqueuer.codegen.registerStaticUse(element);
-      return constant;
+      return signalNotCompileTimeConstant(send);
+    } else if (send.isCall) {
+      if (element === compiler.identicalFunction && send.argumentCount() == 2) {
+        Constant left = evaluate(send.argumentsNode.nodes.head);
+        Constant right = evaluate(send.argumentsNode.nodes.tail.head);
+        Constant result = constantSystem.identity.fold(left, right);
+        if (result !== null) return result;
+      }
+      return signalNotCompileTimeConstant(send);
     } else if (send.isPrefix) {
       assert(send.isOperator);
       Constant receiverConstant = evaluate(send.receiver);
       if (receiverConstant == null) return null;
       Operator op = send.selector;
       Constant folded;
       switch (op.source.stringValue) {
         case "!":
           folded = constantSystem.not.fold(receiverConstant);
           break;
@@ skipping 67 matching lines @@
           break;
         case ">=":
           folded = constantSystem.greaterEqual.fold(left, right);
           break;
         case "==":
           if (left.isPrimitive() && right.isPrimitive()) {
             folded = constantSystem.equal.fold(left, right);
           }
           break;
         case "===":
-          if (left.isPrimitive() && right.isPrimitive()) {
-            folded = constantSystem.identity.fold(left, right);
-          }
+          folded = constantSystem.identity.fold(left, right);
           break;
         case "!=":
           if (left.isPrimitive() && right.isPrimitive()) {
             BoolConstant areEquals = constantSystem.equal.fold(left, right);
             if (areEquals === null) {
               folded = null;
             } else {
               folded = areEquals.negate();
             }
           }
           break;
         case "!==":
-          if (left.isPrimitive() && right.isPrimitive()) {
-            BoolConstant areIdentical =
-                constantSystem.identity.fold(left, right);
-            if (areIdentical === null) {
-              folded = null;
-            } else {
-              folded = areIdentical.negate();
-            }
+          BoolConstant areIdentical =
+              constantSystem.identity.fold(left, right);
+          if (areIdentical === null) {
+            folded = null;
+          } else {
+            folded = areIdentical.negate();
           }
           break;
       }
       if (folded === null) return signalNotCompileTimeConstant(send);
       return folded;
     }
     return signalNotCompileTimeConstant(send);
   }
 
   Constant visitSendSet(SendSet node) {
@@ skipping 248 matching lines @@
       Constant fieldValue = fieldValues[field];
       if (fieldValue === null) {
         // Use the default value.
         fieldValue = compiler.compileConstant(field);
       }
       jsNewArguments.add(fieldValue);
     });
     return jsNewArguments;
   }
 }