Generative constructor factories for native objects

sdk/lib/_internal/compiler/implementation/ssa/builder.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.
 
 part of ssa;
 
 /**
  * A special element for the extra parameter taken by intercepted
  * methods. We need to override [Element.computeType] because our
  * optimizers may look at its declared type.
@@ skipping 257 matching lines @@
       builder.graph.thisInstruction = thisInstruction;
       builder.graph.entry.addAtEntry(thisInstruction);
       directLocals[closureData.thisElement] = thisInstruction;
     }
 
     // If this method is an intercepted method, add the extra
     // parameter to it, that is the actual receiver for intercepted
     // classes, or the same as [:this:] for non-intercepted classes.
     ClassElement cls = element.getEnclosingClass();
     JavaScriptBackend backend = compiler.backend;
+    bool isNativeUpgradeFactory = element.isGenerativeConstructor()

[ngeoffray, 2013/10/17 09:08:59]

What is a native upgrade factory?

[sra1, 2013/10/18 04:09:32]

Added comment

+        && Elements.isNativeOrExtendsNative(cls);
     if (backend.isInterceptedMethod(element)) {
       bool isInterceptorClass = backend.isInterceptorClass(cls.declaration);
       SourceString name = isInterceptorClass
           ? const SourceString('receiver')
           : const SourceString('_');
       Element parameter = new InterceptedElement(
           cls.computeType(compiler), name, element);
       HParameterValue value = new HParameterValue(parameter);
       builder.graph.explicitReceiverParameter = value;
       builder.graph.entry.addAfter(
           directLocals[closureData.thisElement], value);
       if (isInterceptorClass) {
         // Only use the extra parameter in intercepted classes.
         directLocals[closureData.thisElement] = value;
       }
       value.instructionType = builder.getTypeOfThis();
+    } else if (isNativeUpgradeFactory) {
+      bool isInterceptorClass = backend.isInterceptorClass(cls.declaration);
+      Element parameter = new InterceptedElement(
+          cls.computeType(compiler), const SourceString('receiver'), element);
+      HParameterValue value = new HParameterValue(parameter);
+      builder.graph.explicitReceiverParameter = value;
+      builder.graph.entry.addAtEntry(value);
+      value.instructionType = builder.getTypeOfThis();

[ngeoffray, 2013/10/17 09:08:59]

This seems very similar to the code line 281 to 295. What prevents the sharing?
Can't you just change line 291 to also check isNativeUpgradeFactory?

[sra1, 2013/10/18 04:09:32]

In the fixed version there are more differences, enough to make separate
branches no longer the the version you propose.

     }
   }
 
   bool hasValueForDirectLocal(Element element) {
     assert(element != null);
     assert(isAccessedDirectly(element));
     return directLocals[element] != null;
   }
 
   /**
@@ skipping 956 matching lines @@
       }
 
       // Don't inline operator== methods if the parameter can be null.
       if (element.name == const SourceString('==')) {
         if (element.getEnclosingClass() != compiler.objectClass
             && providedArguments[1].canBeNull()) {
           return false;
         }
       }
 
+      // Generative constructors of native classes should not be called directly
+      // and have an extra argument that causes problems with inlining.
+      if (element.isGenerativeConstructor()
+          && Elements.isNativeOrExtendsNative(element.getEnclosingClass())) {
+        return false;
+      }
+
       // A generative constructor body is not seen by global analysis,
       // so we should not query for its type.
       if (!element.isGenerativeConstructorBody()) {
         // Don't inline if the return type was inferred to be non-null empty.
         // This means that the function always throws an exception.
         TypeMask returnType =
             compiler.typesTask.getGuaranteedReturnTypeOfElement(element);
         if (returnType != null
             && returnType.isEmpty
             && !returnType.isNullable) {
@@ skipping 299 matching lines @@
    */
   void buildFieldInitializers(ClassElement classElement,
                               Map<Element, HInstruction> fieldValues) {
     assert(invariant(classElement, classElement.isImplementation));
     classElement.forEachInstanceField(
         (ClassElement enclosingClass, Element member) {
           compiler.withCurrentElement(member, () {
             TreeElements definitions = compiler.analyzeElement(member);
             Node node = member.parseNode(compiler);
             SendSet assignment = node.asSendSet();
-            HInstruction value;
             if (assignment == null) {
-              value = graph.addConstantNull(compiler);
+              // Unassigned fields of native classes are not initialized to
+              // prevent overwriting pre-initialized native properties.
+              if (!Elements.isNativeOrExtendsNative(classElement)) {
+                HInstruction value = graph.addConstantNull(compiler);

[ngeoffray, 2013/10/17 09:08:59]

Avoid the temporary?

[sra1, 2013/10/18 04:09:32]

Done.

+                fieldValues[member] = value;
+              }
             } else {
               Node right = assignment.arguments.head;
               TreeElements savedElements = elements;
               elements = definitions;
               // In case the field initializer uses closures, run the
               // closure to class mapper.
               compiler.closureToClassMapper.computeClosureToClassMapping(
                   member, node, elements);
               inlinedFrom(member, () => right.accept(this));
               elements = savedElements;
-              value = pop();
+              HInstruction value = pop();
+              fieldValues[member] = value;

[ngeoffray, 2013/10/17 09:08:59]

Avoid the temporary?

[sra1, 2013/10/18 04:09:32]

Done.

             }
-            fieldValues[member] = value;
           });
         });
   }
 
   /**
    * Build the factory function corresponding to the constructor
    * [functionElement]:
    *  - Initialize fields with the values of the field initializers of the
    *    current constructor and super constructors or constructors redirected
    *    to, starting from the current constructor.
    *  - Call the constructor bodies, starting from the constructor(s) in the
    *    super class(es).
    */
   HGraph buildFactory(FunctionElement functionElement) {
     functionElement = functionElement.implementation;
     ClassElement classElement =
         functionElement.getEnclosingClass().implementation;
+    bool isNativeUpgradeFactory =
+        Elements.isNativeOrExtendsNative(classElement);
     FunctionExpression function = functionElement.parseNode(compiler);
     // Note that constructors (like any other static function) do not need
     // to deal with optional arguments. It is the callers job to provide all
     // arguments as if they were positional.
 
     if (inliningStack.isEmpty) {
       // The initializer list could contain closures.
       openFunction(functionElement, function);
     }
 
@@ skipping 15 matching lines @@
       }
     });
 
     // Analyze the constructor and all referenced constructors and collect
     // initializers and constructor bodies.
     List<FunctionElement> constructors = <FunctionElement>[functionElement];
     buildInitializers(functionElement, constructors, fieldValues);
 
     // Call the JavaScript constructor with the fields as argument.
     List<HInstruction> constructorArguments = <HInstruction>[];
+    List<Element> fields = <Element>[];
+
     classElement.forEachInstanceField(
         (ClassElement enclosingClass, Element member) {
-          constructorArguments.add(potentiallyCheckType(
-              fieldValues[member], member.computeType(compiler)));
+          HInstruction value = fieldValues[member];
+          if (value == null) {
+            // Uninitialized native fields are pre-initialized by the native
+            // implementation.
+            assert(isNativeUpgradeFactory);
+          } else {
+            fields.add(member);
+            constructorArguments.add(
+                potentiallyCheckType(value, member.computeType(compiler)));
+          }
         },
         includeSuperAndInjectedMembers: true);
 
     InterfaceType type = classElement.computeType(compiler);
     HType ssaType = new HType.nonNullExact(classElement, compiler);
     List<DartType> instantiatedTypes;
     addInlinedInstantiation(type);
     if (!currentInlinedInstantiations.isEmpty) {
       instantiatedTypes = new List<DartType>.from(currentInlinedInstantiations);
     }
-    HForeignNew newObject = new HForeignNew(classElement,
-                                            ssaType,
-                                            constructorArguments,
-                                            instantiatedTypes);
-    add(newObject);
+
+    HInstruction newObject;
+    if (!isNativeUpgradeFactory) {
+      newObject = new HForeignNew(classElement,
+          ssaType,
+          constructorArguments,
+          instantiatedTypes);
+      add(newObject);
+    } else {
+      // Bulk assign to the initialized fields.
+      newObject = graph.explicitReceiverParameter;
+      // Null guard ensures an error if we are being called from an explicit
+      // 'new' of the constructor instead of via an upgrade. It is optimized out
+      // if there are field initializers.
+      add(new HFieldGet(null, newObject, isAssignable: false));
+      for (int i = 0; i < fields.length; i++) {
+        add(new HFieldSet(fields[i], newObject, constructorArguments[i]));
+      }
+    }
     removeInlinedInstantiation(type);
     // Create the runtime type information, if needed.
     if (backend.classNeedsRti(classElement)) {
       List<HInstruction> rtiInputs = <HInstruction>[];
       classElement.typeVariables.forEach((TypeVariableType typeVariable) {
         rtiInputs.add(localsHandler.readLocal(typeVariable.element));
       });
       callSetRuntimeTypeInfo(classElement, rtiInputs, newObject);
     }
 
     // Generate calls to the constructor bodies.
+    HInstruction interceptor = null;
     for (int index = constructors.length - 1; index >= 0; index--) {
       FunctionElement constructor = constructors[index];
       assert(invariant(functionElement, constructor.isImplementation));
       ConstructorBodyElement body = getConstructorBody(constructor);
       if (body == null) continue;
+
       List bodyCallInputs = <HInstruction>[];
+      if (isNativeUpgradeFactory) {
+        if (interceptor == null) {
+          Constant constant = new InterceptorConstant(
+              classElement.computeType(compiler));
+          interceptor = graph.addConstant(constant, compiler);
+        }
+        bodyCallInputs.add(interceptor);
+      }
       bodyCallInputs.add(newObject);
       TreeElements elements =
           compiler.enqueuer.resolution.getCachedElements(constructor);
       Node node = constructor.parseNode(compiler);
       ClosureClassMap parameterClosureData =
           compiler.closureToClassMapper.getMappingForNestedFunction(node);
 
-
       FunctionSignature functionSignature = body.computeSignature(compiler);
       // Provide the parameters to the generative constructor body.
       functionSignature.orderedForEachParameter((parameter) {
         // If [parameter] is boxed, it will be a field in the box passed as the
         // last parameter. So no need to directly pass it.
         if (!localsHandler.isBoxed(parameter)) {
           bodyCallInputs.add(localsHandler.readLocal(parameter));
         }
       });
 
       ClassElement currentClass = constructor.getEnclosingClass();
       if (backend.classNeedsRti(currentClass)) {
         // If [currentClass] needs RTI, we add the type variables as
         // parameters of the generative constructor body.
         currentClass.typeVariables.forEach((DartType argument) {
           bodyCallInputs.add(localsHandler.readLocal(argument.element));
         });
       }
 
       // If there are locals that escape (ie mutated in closures), we
       // pass the box to the constructor.
       ClosureScope scopeData = parameterClosureData.capturingScopes[node];
       if (scopeData != null) {
         bodyCallInputs.add(localsHandler.readLocal(scopeData.boxElement));
       }
 
-      if (tryInlineMethod(body, null, bodyCallInputs, function)) {
+      if (!isNativeUpgradeFactory && // TODO(13836): Fix inlining.
+          tryInlineMethod(body, null, bodyCallInputs, function)) {
         pop();
       } else {
         HInvokeConstructorBody invoke =
             new HInvokeConstructorBody(body.declaration, bodyCallInputs);
         invoke.sideEffects =
             compiler.world.getSideEffectsOfElement(constructor);
         add(invoke);
       }
     }
     if (inliningStack.isEmpty) {
@@ skipping 1820 matching lines @@
     }
 
     bool isRedirected = functionElement.isRedirectingFactory;
     InterfaceType type = elements.getType(node);
     DartType expectedType = type;
     if (isRedirected) {
       type = functionElement.computeTargetType(compiler, type);
     }
 
     var inputs = <HInstruction>[];
+    if (constructor.isGenerativeConstructor() &&
+        Elements.isNativeOrExtendsNative(constructor.getEnclosingClass())) {
+      // Native class generative constructors take a pre-constructed object.
+      inputs.add(graph.addConstantNull(compiler));
+    }
     // TODO(5347): Try to avoid the need for calling [implementation] before
     // calling [addStaticSendArgumentsToList].
     bool succeeded = addStaticSendArgumentsToList(selector, send.arguments,
                                                   constructor.implementation,
                                                   inputs);
     if (!succeeded) {
       generateWrongArgumentCountError(send, constructor, send.arguments);
       return;
     }
 
@@ skipping 1977 matching lines @@
           new HSubGraphBlockInformation(elseBranch.graph));
 
     HBasicBlock conditionStartBlock = conditionBranch.block;
     conditionStartBlock.setBlockFlow(info, joinBlock);
     SubGraph conditionGraph = conditionBranch.graph;
     HIf branch = conditionGraph.end.last;
     assert(branch is HIf);
     branch.blockInformation = conditionStartBlock.blockFlow;
   }
 }