dart2js cps: Generate direct field accesses a build-time.

pkg/compiler/lib/src/cps_ir/cps_ir_builder.dart

 // Copyright (c) 2013, 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.ir_builder;
 
 import '../compile_time_constants.dart' show BackendConstantEnvironment;
 import '../constants/constant_system.dart';
 import '../constants/values.dart' show ConstantValue, PrimitiveConstantValue;
 import '../dart_types.dart';
@@ skipping 851 matching lines @@
                                       List<ir.Primitive> arguments) {
     return _buildInvokeDynamic(receiver, selector, mask, arguments);
   }
 
   /// Create a dynamic getter invocation on [receiver] where the getter name is
   /// defined by [selector].
   ir.Primitive buildDynamicGet(ir.Primitive receiver,
                                Selector selector,
                                TypeMask mask) {
     assert(selector.isGetter);
-    return _buildInvokeDynamic(
-        receiver, selector, mask, const <ir.Primitive>[]);
+    FieldElement field = program.locateSingleField(selector, mask);
+    if (field != null) {
+      // If the world says this resolves to a unique field, then it MUST be
+      // treated as a field access, since the getter might not be emitted.
+      return buildFieldGet(receiver, field);
+    } else {
+      return _buildInvokeDynamic(
+          receiver, selector, mask, const <ir.Primitive>[]);
+    }
   }
 
   /// Create a dynamic setter invocation on [receiver] where the setter name and
   /// argument are defined by [selector] and [value], respectively.
   ir.Primitive buildDynamicSet(ir.Primitive receiver,
                                Selector selector,
                                TypeMask mask,
                                ir.Primitive value) {
     assert(selector.isSetter);
-    _buildInvokeDynamic(receiver, selector, mask, <ir.Primitive>[value]);
+    FieldElement field = program.locateSingleField(selector, mask);
+    if (field != null) {
+      // If the world says this resolves to a unique field, then it MUST be
+      // treated as a field access, since the setter might not be emitted.
+      buildFieldSet(receiver, field, value);
+    } else {
+      _buildInvokeDynamic(receiver, selector, mask, <ir.Primitive>[value]);
+    }
     return value;
   }
 
   /// Create a dynamic index set invocation on [receiver] with the provided
   /// [index] and [value].
   ir.Primitive  buildDynamicIndexSet(ir.Primitive receiver,
                                      TypeMask mask,
                                      ir.Primitive index,
                                      ir.Primitive value) {
     _buildInvokeDynamic(
@@ skipping 1494 matching lines @@
   /// Creates an access to the receiver from the current (or enclosing) method.
   ///
   /// If inside a closure class, [buildThis] will redirect access through
   /// closure fields in order to access the receiver from the enclosing method.
   ir.Primitive buildThis() {
     if (state.enclosingThis != null) return state.enclosingThis;
     assert(state.thisParameter != null);
     return state.thisParameter;
   }
 
+  ir.Primitive buildFieldGet(ir.Primitive receiver, FieldElement target) {
+    return addPrimitive(new ir.GetField(receiver, target));
+  }
+
+  void buildFieldSet(ir.Primitive receiver, 
+                     FieldElement target, 
+                     ir.Primitive value) {
+    add(new ir.SetField(receiver, target, value));
+  }
+
   ir.Primitive buildSuperFieldGet(FieldElement target) {
     return addPrimitive(new ir.GetField(buildThis(), target));
   }
 
   ir.Primitive buildSuperFieldSet(FieldElement target, ir.Primitive value) {
     add(new ir.SetField(buildThis(), target, value));
     return value;
   }
 
   ir.Primitive buildInvokeDirectly(FunctionElement target,
@@ skipping 290 matching lines @@
 }
 
 class SwitchCaseInfo {
   final List<ir.Primitive> constants = <ir.Primitive>[];
   final SubbuildFunction buildBody;
 
   SwitchCaseInfo(this.buildBody);
 
   void addConstant(ir.Primitive constant) => constants.add(constant);
 }