RFC: Resolution based tree-shaking.

dart/lib/compiler/implementation/resolver.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.
 
 interface TreeElements {
   Element operator[](Node node);
   Selector getSelector(Send send);
   Type getType(TypeAnnotation annotation);
 }
 
@@ skipping 331 matching lines @@
   }
 
   void resolveImplicitSuperConstructorSend(FunctionElement constructor,
                                            FunctionExpression functionNode) {
     // If the class has a super resolve the implicit super call.
     ClassElement classElement = constructor.enclosingElement;
     ClassElement superClass = classElement.superclass;
     if (classElement != visitor.compiler.objectClass) {
       assert(superClass !== null);
       assert(superClass.isResolved);
-      resolveSuperOrThis(constructor, true, true, const SourceString(''),
-                         Selector.INVOCATION_0, functionNode);
+      var element = resolveSuperOrThis(constructor, true, true,
+                                       const SourceString(''),
+                                       Selector.INVOCATION_0, functionNode);
+      visitor.compiler.enqueuer.resolution.registerStaticUse(element);

[kasperl, 2012/06/12 05:50:12]

Would visitor.world work?

[ahe, 2012/06/12 06:22:49]

visitor.world.

[ahe, 2012/06/12 10:56:11]

Done.

[ahe, 2012/06/12 10:56:11]

Done.

     }
   }
 
   Element resolveSuperOrThis(FunctionElement constructor,
                              bool isSuperCall,
                              bool isImplicitSuperCall,
                              SourceString constructorName,
                              Selector selector,
                              Node diagnosticNode) {
     ClassElement lookupTarget = constructor.enclosingElement;
@@ skipping 353 matching lines @@
       super(compiler) {
     LibraryElement library = element.getLibrary();
     element = element.getEnclosingMember();
     if (element !== null) {
       context = new ClassScope(element.enclosingElement, library);
     } else {
       this.context = new TopScope(library);
     }
   }
 
+  Enqueuer get world() => compiler.enqueuer.resolution;
+
   Element lookup(Node node, SourceString name) {
     Element result = context.lookup(name);
     if (!inInstanceContext && result != null && result.isInstanceMember()) {
       error(node, MessageKind.NO_INSTANCE_AVAILABLE, [node]);
     }
     return result;
   }
 
   // Create, or reuse an already created, statement element for a statement.
   TargetElement getOrCreateTargetElement(Node statement) {
@@ skipping 59 matching lines @@
       Element existing = context.add(element);
       if (existing != element) {
         error(node, MessageKind.DUPLICATE_DEFINITION, [node]);
       }
     }
     return element;
   }
 
   Element useElement(Node node, Element element) {
     if (element === null) return null;
-    return mapping[node] = element;
+    mapping[node] = element;
+    if (element.isTopLevel() || element.isMember()) {
+      if (element.isInstanceMember()) {
+        Selector selector = mapping.getSelector(node);
+        if (selector !== null) {
+          world.registerDynamicInvocation(element.name, selector);
+        }
+      } else {
+        if (!element.isPrefix() &&
+            !element.isClass() &&
+            !element.isTypedef() &&
+            !element.isTypeVariable()) {
+          world.registerStaticUse(element);
+        }
+      }
+    } else {
+      assert(enclosingElement ===
+             element.getOutermostEnclosingMemberOrTopLevel());
+    }
+    return element;
   }
 
   Type useType(TypeAnnotation annotation, Type type) {
     if (type !== null) {
       mapping.setType(annotation, type);
       useElement(annotation, type.element);
     }
     return type;
   }
 
@@ skipping 240 matching lines @@
     if (target === compiler.assertMethod && !node.isCall) {
       // We can only use assert by calling it.
       if (!inInstanceContext) {
         error(node, MessageKind.MISSING_ARGUMENTS_TO_ASSERT, [node]);
       }
       target = null;
     }
     // TODO(ngeoffray): Warn if target is null and the send is
     // unqualified.
     useElement(node, target);
+    if (target === null) handleDynamicSend(node);
     if (node.isPropertyAccess) return target;
   }
 
   visitSendSet(SendSet node) {
     Element target = resolveSend(node);
     Element setter = null;
     Element getter = null;
     if (target != null && target.kind == ElementKind.ABSTRACT_FIELD) {
       AbstractFieldElement field = target;
       setter = field.setter;
@@ skipping 15 matching lines @@
       useElement(node.selector, getter);
     } else if (node.isIndex) {
       selector = Selector.INDEX_SET;
     } else {
       selector = Selector.SETTER;
     }
     visit(node.argumentsNode);
     mapping.setSelector(node, selector);
     // TODO(ngeoffray): Warn if target is null and the send is
     // unqualified.
+    handleDynamicSend(node);
     return useElement(node, setter);
   }
 
+  handleDynamicSend(Send node) {
+    Identifier id = node.selector.asIdentifier();
+    if (id === null) return;
+    SourceString name = node.selector.asIdentifier().source;
+    if (node.isIndex && !node.arguments.tail.isEmpty()) {
+      name = Elements.constructOperatorName(
+          const SourceString('operator'),
+          const SourceString('[]='));
+    } else if (node.selector.asOperator() != null) {
+      switch (name.stringValue) {
+        case "===":

[kasperl, 2012/06/12 05:50:12]

Use ' for string literals for consistency?

[ahe, 2012/06/12 10:56:11]

Done.

+        case "!==":
+        case "!":
+        case "&&":
+        case "||":
+        case "is":
+        case ">>>":
+          return null;
+      }
+      if (name === null) return;

[kasperl, 2012/06/12 05:50:12]

Check for name === null before switching on name.stringValue.

[ahe, 2012/06/12 10:56:11]

Removed.

+      name = Elements.constructOperatorName(
+          const SourceString('operator'),
+          name,
+          node.argumentsNode is Prefix);
+    }
+    Selector selector = mapping.getSelector(node);
+    if (Selector.GETTER === selector) {
+      world.registerDynamicGetter(name, selector);
+    } else if (Selector.SETTER === selector) {
+      world.registerDynamicSetter(name, selector);
+      // Also register the getter for compound assignments.
+      world.registerDynamicGetter(name, Selector.GETTER);
+    } else {
+      world.registerDynamicInvocation(name, selector);
+    }
+    var interceptor = new Interceptors(compiler).getStaticInterceptor(
+        name,
+        node.argumentCount());
+    if (interceptor !== null) {
+      world.registerStaticUse(interceptor);
+    }
+  }
+
   visitLiteralInt(LiteralInt node) {
   }
 
   visitLiteralDouble(LiteralDouble node) {
   }
 
   visitLiteralBool(LiteralBool node) {
   }
 
   visitLiteralString(LiteralString node) {
@@ skipping 47 matching lines @@
     FunctionElement constructor = resolveConstructor(node);
     handleArguments(node.send);
     if (constructor === null) return null;
     // TODO(karlklose): handle optional arguments.
     if (node.send.argumentCount() != constructor.parameterCount(compiler)) {
       // TODO(ngeoffray): resolution error with wrong number of
       // parameters. We cannot do this rigth now because of the
       // List constructor.
     }
     useElement(node.send, constructor);
+    compiler.withCurrentElement(constructor, () {
+      FunctionExpression tree = constructor.parseNode(compiler);
+      compiler.resolver.resolveConstructorImplementation(constructor, tree);
+    });
+    world.registerStaticUse(constructor.defaultImplementation);
+    world.registerInstantiatedClass(
+        constructor.defaultImplementation.enclosingElement);
+    constructor.defaultImplementation.enclosingElement.forEachInstanceField(
+        includeBackendMembers: false,
+        includeSuperMembers: true,
+        f: (ClassElement enclosingClass, Element member) {
+          world.addToWorkList(member);
+        });
     return null;
   }
 
   TypeAnnotation getTypeAnnotationFromSend(Send send) {
     if (send.selector.asTypeAnnotation() !== null) {
       return send.selector;
     } else if (send.selector.asSend() !== null) {
       Send selector = send.selector;
       if (selector.receiver.asTypeAnnotation() !== null) {
         return selector.receiver;
@@ skipping 831 matching lines @@
 
   TopScope(LibraryElement library) : super(null, library);
   Element lookup(SourceString name) {
     return library.find(name);
   }
 
   Element add(Element newElement) {
     throw "Cannot add an element in the top scope";
   }
 }