Create and use new change/depends flags for the GVN analysis.

lib/compiler/implementation/world.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.
 
 class World {
   final Compiler compiler;
   final Map<ClassElement, Set<ClassElement>> subtypes;
   final Set<ClassElement> classesNeedingRti;
   final Map<ClassElement, Set<ClassElement>> rtiDependencies;
   final FunctionSet userDefinedGetters;
+  final FunctionSet userDefinedSetters;
 
   World(Compiler compiler)
       : subtypes = new Map<ClassElement, Set<ClassElement>>(),
         userDefinedGetters = new FunctionSet(compiler),
+        userDefinedSetters = new FunctionSet(compiler),
         classesNeedingRti = new Set<ClassElement>(),
         rtiDependencies = new Map<ClassElement, Set<ClassElement>>(),
         this.compiler = compiler;
 
   void populate() {
     void addSubtypes(ClassElement cls) {
       if (cls.resolutionState != STATE_DONE) {
         compiler.internalErrorOnElement(
             cls, 'Class "${cls.name.slowToString()}" is not resolved.');
       }
@@ skipping 57 matching lines @@
     Set<ClassElement> classes =
         rtiDependencies.putIfAbsent(element, () => new Set<ClassElement>());
     classes.add(dependency);
   }
 
   void recordUserDefinedGetter(Element element) {
     assert(element.isGetter());
     userDefinedGetters.add(element);
   }
 
+  void recordUserDefinedSetter(Element element) {
+    assert(element.isSetter());
+    userDefinedSetters.add(element);
+  }
+
   bool hasAnyUserDefinedGetter(Selector selector) {
     return userDefinedGetters.hasAnyElementMatchingSelector(selector);
   }
 
+  bool hasAnyUserDefinedSetter(Selector selector) {
+    return userDefinedSetters.hasAnyElementMatchingSelector(selector);
+  }
+
   void registerUsedElement(Element element) {
-    if (element.isMember() && element.isGetter()) {
-      // We're collecting user-defined getters to let the codegen know which
-      // field accesses might have side effects.
-      userDefinedGetters.add(element);
+    if (element.isMember()) {
+      if (element.isGetter()) {
+        // We're collecting user-defined getters to let the codegen know which
+        // field accesses might have side effects.
+        recordUserDefinedGetter(element);
+      } else if (element.isSetter()) {
+        recordUserDefinedSetter(element);
+      }
     }
   }
 
   /**
    * Returns a [MemberSet] that contains the possible targets of the given
    * [selector] on a receiver with the given [type]. This includes all sub
    * types.
    */
   MemberSet _memberSetFor(DartType type, Selector selector) {
     assert(compiler !== null);
@@ skipping 58 matching lines @@
   final SourceString name;
 
   MemberSet(SourceString this.name) : elements = new Set<Element>();
 
   void add(Element element) {
     elements.add(element);
   }
 
   bool isEmpty() => elements.isEmpty();
 }