dart2js: Use frequency of occurence to sort metadata indices.

pkg/compiler/lib/src/constants/values.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.
 
 library dart2js.constants.values;
 
 import '../core_types.dart';
 import '../dart_types.dart';
 import '../dart2jslib.dart'
     show assertDebugMode;
@@ skipping 14 matching lines @@
   R visitNull(NullConstantValue constant, A arg);
   R visitInt(IntConstantValue constant, A arg);
   R visitDouble(DoubleConstantValue constant, A arg);
   R visitBool(BoolConstantValue constant, A arg);
   R visitString(StringConstantValue constant, A arg);
   R visitList(ListConstantValue constant, A arg);
   R visitMap(MapConstantValue constant, A arg);
   R visitConstructed(ConstructedConstantValue constant, A arg);
   R visitType(TypeConstantValue constant, A arg);
   R visitInterceptor(InterceptorConstantValue constant, A arg);
-  R visitDummy(DummyConstantValue constant, A arg);
+  R visitSynthetic(SyntheticConstantValue constant, A arg);
   R visitDeferred(DeferredConstantValue constant, A arg);
 }
 
 abstract class ConstantValue {
   const ConstantValue();
 
   /// `true` if this is a valid constant value.
   bool get isConstant => true;
 
   bool get isNull => false;
@@ skipping 27 matching lines @@
   List<ConstantValue> getDependencies();
 
   accept(ConstantValueVisitor visitor, arg);
 
   /// The value of this constant in Dart syntax, if possible.
   ///
   /// For [ConstructedConstantValue]s there is no way to create a valid const
   /// expression from the value so the unparse of these is best effort.
   ///
   /// For the synthetic constants, [DeferredConstantValue],
-  /// [DummyConstantValue], [InterceptorConstantValue] the unparse is
+  /// [SyntheticConstantValue], [InterceptorConstantValue] the unparse is
   /// descriptive only.
   String unparse();
 
   /// Returns a structured representation of this constant suited for debugging.
   String toStructuredString();
 
   String toString() {
     assertDebugMode("Use Constant.unparse() or Constant.toStructuredString() "
                     "instead of Constant.toString().");
     return toStructuredString();
@@ skipping 502 matching lines @@
 
   String unparse() {
     return 'interceptor($dispatchedType)';
   }
 
   String toStructuredString() {
     return 'InterceptorConstant(${dispatchedType.getStringAsDeclared("o")})';
   }
 }
 
-// TODO(johnniwinther): Remove this class.
-class DummyConstantValue extends ConstantValue {
-  final ti.TypeMask typeMask;
+class SyntheticConstantValue extends ConstantValue {
+  final payload;
+  final kind;
 
-  DummyConstantValue(this.typeMask);
+  SyntheticConstantValue(this.kind, this.payload);
 
   bool get isDummy => true;
 
   bool operator ==(other) {
-    return other is DummyConstantValue
-        && typeMask == other.typeMask;
+    return other is SyntheticConstantValue
+        && payload == other.payload;
   }
 
-  get hashCode => typeMask.hashCode;
+  get hashCode => payload.hashCode * 17 + kind.hashCode;
 
   List<ConstantValue> getDependencies() => const <ConstantValue>[];
 
-  accept(ConstantValueVisitor visitor, arg) => visitor.visitDummy(this, arg);
+  accept(ConstantValueVisitor visitor, arg) {
+    return visitor.visitSynthetic(this, arg);
+  }
 
   DartType getType(CoreTypes types) => const DynamicType();
 
-  String unparse() => 'dummy($typeMask)';
+  String unparse() => 'synthetic($kind, $payload)';
 
-  String toStructuredString() => 'DummyConstant($typeMask)';
+  String toStructuredString() => 'SyntheticConstant($kind, $payload)';
 }
 
 class ConstructedConstantValue extends ObjectConstantValue {
   final Map<FieldElement, ConstantValue> fields;
   final int hashCode;
 
   ConstructedConstantValue(InterfaceType type,
                            Map<FieldElement, ConstantValue> fields)
     : this.fields = fields,
       hashCode = Hashing.mapHash(fields, Hashing.objectHash(type)),
@@ skipping 102 matching lines @@
 
   @override
   DartType getType(CoreTypes types) => const DynamicType();
 
   @override
   String toStructuredString() => 'NonConstant';
 
   @override
   String unparse() => '>>non-constant<<';
 }