dart2js: Move most of the code_emitter_task code into the program-builder.

pkg/compiler/lib/src/js_emitter/code_emitter_task.dart

Index: pkg/compiler/lib/src/js_emitter/code_emitter_task.dart
diff --git a/pkg/compiler/lib/src/js_emitter/code_emitter_task.dart b/pkg/compiler/lib/src/js_emitter/code_emitter_task.dart
index b8fa032d80e5530d90643eef59232bdb439b2655..7d77bf3ce5bd9ff388b8794f5325846f0884baa2 100644
--- a/pkg/compiler/lib/src/js_emitter/code_emitter_task.dart
+++ b/pkg/compiler/lib/src/js_emitter/code_emitter_task.dart
@@ -21,34 +21,19 @@ class CodeEmitterTask extends CompilerTask {
   OldEmitter oldEmitter;
   Emitter emitter;
 
-  final Set<ClassElement> neededClasses = new Set<ClassElement>();
-  Set<ClassElement> classesOnlyNeededForRti;
-  final Map<OutputUnit, List<ClassElement>> outputClassLists =
-      new Map<OutputUnit, List<ClassElement>>();
-  final Map<OutputUnit, List<ConstantValue>> outputConstantLists =
-      new Map<OutputUnit, List<ConstantValue>>();
-  final Map<OutputUnit, List<Element>> outputStaticLists =
-      new Map<OutputUnit, List<Element>>();
-  final Map<OutputUnit, List<VariableElement>> outputStaticNonFinalFieldLists =
-      new Map<OutputUnit, List<VariableElement>>();
-  final Map<OutputUnit, Set<LibraryElement>> outputLibraryLists =
-      new Map<OutputUnit, Set<LibraryElement>>();
-
-  /// True, if the output contains a constant list.
-  ///
-  /// This flag is updated in [computeNeededConstants].
-  bool outputContainsConstantList = false;
-
-  final List<ClassElement> nativeClassesAndSubclasses = <ClassElement>[];
-
   /// Records if a type variable is read dynamically for type tests.
   final Set<TypeVariableElement> readTypeVariables =
       new Set<TypeVariableElement>();
 
-  List<TypedefElement> typedefsNeededForReflection;
-
   JavaScriptBackend get backend => compiler.backend;
 
+  @deprecated
+  // This field should be removed. It's currently only needed for dump-info and
+  // tests.
+  // The field is set after the program has been emitted.
+  /// Contains a list of all classes that are emitted.
+  Set<ClassElement> neededClasses;
+
   CodeEmitterTask(Compiler compiler, Namer namer, bool generateSourceMap)
       : super(compiler),
         this.namer = namer,
@@ -134,277 +119,25 @@ class CodeEmitterTask extends CompilerTask {
     readTypeVariables.add(element);
   }
 
-  Set<ClassElement> computeInterceptorsReferencedFromConstants() {
-    Set<ClassElement> classes = new Set<ClassElement>();
-    JavaScriptConstantCompiler handler = backend.constants;
-    List<ConstantValue> constants = handler.getConstantsForEmission();
-    for (ConstantValue constant in constants) {
-      if (constant is InterceptorConstantValue) {
-        InterceptorConstantValue interceptorConstant = constant;
-        classes.add(interceptorConstant.dispatchedType.element);
-      }
-    }
-    return classes;
-  }
-
-  /**
-   * Return a function that returns true if its argument is a class
-   * that needs to be emitted.
-   */
-  Function computeClassFilter() {
-    if (backend.isTreeShakingDisabled) return (ClassElement cls) => true;
-
-    Set<ClassElement> unneededClasses = new Set<ClassElement>();
-    // The [Bool] class is not marked as abstract, but has a factory
-    // constructor that always throws. We never need to emit it.
-    unneededClasses.add(compiler.boolClass);
-
-    // Go over specialized interceptors and then constants to know which
-    // interceptors are needed.
-    Set<ClassElement> needed = new Set<ClassElement>();
-    backend.specializedGetInterceptors.forEach(
-        (_, Iterable<ClassElement> elements) {
-          needed.addAll(elements);
-        }
-    );
-
-    // Add interceptors referenced by constants.
-    needed.addAll(computeInterceptorsReferencedFromConstants());
-
-    // Add unneeded interceptors to the [unneededClasses] set.
-    for (ClassElement interceptor in backend.interceptedClasses) {
-      if (!needed.contains(interceptor)
-          && interceptor != compiler.objectClass) {
-        unneededClasses.add(interceptor);
-      }
-    }
-
-    // These classes are just helpers for the backend's type system.
-    unneededClasses.add(backend.jsMutableArrayClass);
-    unneededClasses.add(backend.jsFixedArrayClass);
-    unneededClasses.add(backend.jsExtendableArrayClass);
-    unneededClasses.add(backend.jsUInt32Class);
-    unneededClasses.add(backend.jsUInt31Class);
-    unneededClasses.add(backend.jsPositiveIntClass);
-
-    return (ClassElement cls) => !unneededClasses.contains(cls);
-  }
-
-  /**
-   * Compute all the constants that must be emitted.
-   */
-  void computeNeededConstants() {
-    // Make sure we retain all metadata of all elements. This could add new
-    // constants to the handler.
-    if (backend.mustRetainMetadata) {
-      // TODO(floitsch): verify that we don't run through the same elements
-      // multiple times.
-      for (Element element in backend.generatedCode.keys) {
-        if (backend.isAccessibleByReflection(element)) {
-          bool shouldRetainMetadata = backend.retainMetadataOf(element);
-          if (shouldRetainMetadata &&
-              (element.isFunction || element.isConstructor ||
-               element.isSetter)) {
-            FunctionElement function = element;
-            function.functionSignature.forEachParameter(
-                backend.retainMetadataOf);
-          }
-        }
-      }
-      for (ClassElement cls in neededClasses) {
-        final onlyForRti = classesOnlyNeededForRti.contains(cls);
-        if (!onlyForRti) {
-          backend.retainMetadataOf(cls);
-          oldEmitter.classEmitter.visitFields(cls, false,
-              (Element member,
-               jsAst.Name name,
-               jsAst.Name accessorName,
-               bool needsGetter,
-               bool needsSetter,
-               bool needsCheckedSetter) {
-            bool needsAccessor = needsGetter || needsSetter;
-            if (needsAccessor && backend.isAccessibleByReflection(member)) {
-              backend.retainMetadataOf(member);
-            }
-          });
-        }
-      }
-      typedefsNeededForReflection.forEach(backend.retainMetadataOf);
-    }
-
-    JavaScriptConstantCompiler handler = backend.constants;
-    List<ConstantValue> constants = handler.getConstantsForEmission(
-        compiler.hasIncrementalSupport ? null : emitter.compareConstants);
-    for (ConstantValue constant in constants) {
-      if (emitter.isConstantInlinedOrAlreadyEmitted(constant)) continue;
-
-      if (constant.isList) outputContainsConstantList = true;
-
-      OutputUnit constantUnit =
-          compiler.deferredLoadTask.outputUnitForConstant(constant);
-      if (constantUnit == null) {
-        // The back-end introduces some constants, like "InterceptorConstant" or
-        // some list constants. They are emitted in the main output-unit.
-        // TODO(sigurdm): We should track those constants.
-        constantUnit = compiler.deferredLoadTask.mainOutputUnit;
-      }
-      outputConstantLists.putIfAbsent(
-          constantUnit, () => new List<ConstantValue>()).add(constant);
-    }
-  }
-
-  /// Compute all the classes and typedefs that must be emitted.
-  void computeNeededDeclarations(Set<ClassElement> rtiNeededClasses) {
-    // Compute needed typedefs.
-    typedefsNeededForReflection = Elements.sortedByPosition(
-        compiler.world.allTypedefs
-            .where(backend.isAccessibleByReflection)
-            .toList());
-
-    // Compute needed classes.
-    Set<ClassElement> instantiatedClasses =
-        compiler.codegenWorld.directlyInstantiatedClasses
-            .where(computeClassFilter()).toSet();
-
-    void addClassWithSuperclasses(ClassElement cls) {
-      neededClasses.add(cls);
-      for (ClassElement superclass = cls.superclass;
-          superclass != null;
-          superclass = superclass.superclass) {
-        neededClasses.add(superclass);
-      }
-    }
-
-    void addClassesWithSuperclasses(Iterable<ClassElement> classes) {
-      for (ClassElement cls in classes) {
-        addClassWithSuperclasses(cls);
-      }
-    }
-
-    // 1. We need to generate all classes that are instantiated.
-    addClassesWithSuperclasses(instantiatedClasses);
-
-    // 2. Add all classes used as mixins.
-    Set<ClassElement> mixinClasses = neededClasses
-        .where((ClassElement element) => element.isMixinApplication)
-        .map(computeMixinClass)
-        .toSet();
-    neededClasses.addAll(mixinClasses);
-
-    // 3. Find all classes needed for rti.
-    // It is important that this is the penultimate step, at this point,
-    // neededClasses must only contain classes that have been resolved and
-    // codegen'd. The rtiNeededClasses may contain additional classes, but
-    // these are thought to not have been instantiated, so we neeed to be able
-    // to identify them later and make sure we only emit "empty shells" without
-    // fields, etc.
-    classesOnlyNeededForRti = rtiNeededClasses.difference(neededClasses);
-
-    neededClasses.addAll(classesOnlyNeededForRti);
-
-    // TODO(18175, floitsch): remove once issue 18175 is fixed.
-    if (neededClasses.contains(backend.jsIntClass)) {
-      neededClasses.add(compiler.intClass);
-    }
-    if (neededClasses.contains(backend.jsDoubleClass)) {
-      neededClasses.add(compiler.doubleClass);
-    }
-    if (neededClasses.contains(backend.jsNumberClass)) {
-      neededClasses.add(compiler.numClass);
-    }
-    if (neededClasses.contains(backend.jsStringClass)) {
-      neededClasses.add(compiler.stringClass);
-    }
-    if (neededClasses.contains(backend.jsBoolClass)) {
-      neededClasses.add(compiler.boolClass);
-    }
-    if (neededClasses.contains(backend.jsArrayClass)) {
-      neededClasses.add(compiler.listClass);
-    }
-
-    // 4. Finally, sort the classes.
-    List<ClassElement> sortedClasses = Elements.sortedByPosition(neededClasses);
-
-    for (ClassElement element in sortedClasses) {
-      if (Elements.isNativeOrExtendsNative(element) &&
-          !classesOnlyNeededForRti.contains(element)) {
-        // For now, native classes and related classes cannot be deferred.
-        nativeClassesAndSubclasses.add(element);
-        assert(invariant(element,
-                         !compiler.deferredLoadTask.isDeferred(element)));
-        outputClassLists.putIfAbsent(compiler.deferredLoadTask.mainOutputUnit,
-            () => new List<ClassElement>()).add(element);
-      } else {
-        outputClassLists.putIfAbsent(
-            compiler.deferredLoadTask.outputUnitForElement(element),
-            () => new List<ClassElement>())
-            .add(element);
-      }
-    }
-  }
-
-  void computeNeededStatics() {
-    bool isStaticFunction(Element element) =>
-        !element.isInstanceMember && !element.isField;
-
-    Iterable<Element> elements =
-        backend.generatedCode.keys.where(isStaticFunction);
-
-    for (Element element in Elements.sortedByPosition(elements)) {
-      List<Element> list = outputStaticLists.putIfAbsent(
-          compiler.deferredLoadTask.outputUnitForElement(element),
-          () => new List<Element>());
-      list.add(element);
-    }
-  }
-
-  void computeNeededStaticNonFinalFields() {
-    JavaScriptConstantCompiler handler = backend.constants;
-    Iterable<VariableElement> staticNonFinalFields = handler
-        .getStaticNonFinalFieldsForEmission()
-        .where(compiler.codegenWorld.allReferencedStaticFields.contains);
-    for (Element element in Elements.sortedByPosition(staticNonFinalFields)) {
-      List<VariableElement> list = outputStaticNonFinalFieldLists.putIfAbsent(
-            compiler.deferredLoadTask.outputUnitForElement(element),
-            () => new List<VariableElement>());
-      list.add(element);
-    }
-  }
-
-  void computeNeededLibraries() {
-    void addSurroundingLibraryToSet(Element element) {
-      OutputUnit unit = compiler.deferredLoadTask.outputUnitForElement(element);
-      LibraryElement library = element.library;
-      outputLibraryLists.putIfAbsent(unit, () => new Set<LibraryElement>())
-          .add(library);
-    }
-
-    backend.generatedCode.keys.forEach(addSurroundingLibraryToSet);
-    neededClasses.forEach(addSurroundingLibraryToSet);
-  }
-
-  void computeAllNeededEntities() {
+  Set<ClassElement> _finalizeRti() {
     // Compute the required type checks to know which classes need a
     // 'is$' method.
     typeTestRegistry.computeRequiredTypeChecks();
     // Compute the classes needed by RTI.
-    Set<ClassElement> rtiClasses = typeTestRegistry.computeRtiNeededClasses();
-
-    computeNeededDeclarations(rtiClasses);
-    computeNeededConstants();
-    computeNeededStatics();
-    computeNeededStaticNonFinalFields();
-    computeNeededLibraries();
+    return typeTestRegistry.computeRtiNeededClasses();
   }
 
   int assembleProgram() {
     return measure(() {
       emitter.invalidateCaches();
 
-      computeAllNeededEntities();
-
-      ProgramBuilder programBuilder = new ProgramBuilder(compiler, namer, this);
-      return emitter.emitProgram(programBuilder);
+      Set<ClassElement> rtiNeededClasses = _finalizeRti();
+      ProgramBuilder programBuilder = new ProgramBuilder(
+          compiler, namer, this, emitter, oldEmitter, rtiNeededClasses);
+      int size = emitter.emitProgram(programBuilder);
+      // TODO(floitsch): we shouldn't need the `neededClasses` anymore.
+      neededClasses = programBuilder.collector.neededClasses;
+      return size;
     });
   }
 }