Lazy implementation of final variables.

lib/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.
 
 class Interceptors {
   Compiler compiler;
   Interceptors(Compiler this.compiler);
 
   SourceString mapOperatorToMethodName(Operator op) {
     String name = op.source.stringValue;
@@ skipping 135 matching lines @@
     : interceptors = new Interceptors(backend.compiler),
       closureDataCache = new HashMap<Node, ClosureData>(),
       emitter = backend.emitter,
       functionsCalledInLoop = new Set<FunctionElement>(),
       selectorsCalledInLoop = new Map<SourceString, Selector>(),
       backend = backend,
       super(backend.compiler);
 
   HGraph build(WorkItem work) {
     return measure(() {
-      FunctionElement element = work.element;
+      Element element = work.element;
       HInstruction.idCounter = 0;
       SsaBuilder builder = new SsaBuilder(this, work);
       HGraph graph;
       ElementKind kind = element.kind;
       if (kind === ElementKind.GENERATIVE_CONSTRUCTOR) {
         graph = compileConstructor(builder, work);
       } else if (kind === ElementKind.GENERATIVE_CONSTRUCTOR_BODY ||
                  kind === ElementKind.FUNCTION ||
                  kind === ElementKind.GETTER ||
                  kind === ElementKind.SETTER) {
         graph = builder.buildMethod(work.element);
+      } else if (kind === ElementKind.FIELD) {
+        graph = builder.buildLazyInitializer(work.element);
       }
       assert(graph.isValid());
-      bool inLoop = functionsCalledInLoop.contains(element);
-      if (!inLoop) {
-        Selector selector = selectorsCalledInLoop[element.name];
-        inLoop = selector !== null && selector.applies(element, compiler);
-      }
-      graph.calledInLoop = inLoop;
+      if (kind !== ElementKind.FIELD) {
+        bool inLoop = functionsCalledInLoop.contains(element);
+        if (!inLoop) {
+          Selector selector = selectorsCalledInLoop[element.name];
+          inLoop = selector !== null && selector.applies(element, compiler);
+        }
+        graph.calledInLoop = inLoop;
 
-      // If there is an estimate of the parameter types assume these types when
-      // compiling.
-      List<HType> parameterTypes =
-          backend.optimisticParameterTypesWithRecompilationOnTypeChange(
-              element);
-      if (parameterTypes != null) {
-        FunctionSignature signature = element.computeSignature(compiler);
-        int i = 0;
-        signature.forEachParameter((Element param) {
-          builder.parameters[param].guaranteedType = parameterTypes[i++];
-        });
+        // If there is an estimate of the parameter types assume these types
+        // when compiling.
+        List<HType> parameterTypes =
+            backend.optimisticParameterTypesWithRecompilationOnTypeChange(
+                element);
+        if (parameterTypes != null) {
+          FunctionElement functionElement = element;
+          FunctionSignature signature =
+              functionElement.computeSignature(compiler);
+          int i = 0;
+          signature.forEachParameter((Element param) {
+            builder.parameters[param].guaranteedType = parameterTypes[i++];
+          });
+        }
       }
 
       if (compiler.tracer.enabled) {
         String name;
         if (element.isMember()) {
           String className = element.getEnclosingClass().name.slowToString();
           String memberName = element.name.slowToString();
           name = "$className.$memberName";
           if (element.kind == ElementKind.GENERATIVE_CONSTRUCTOR_BODY) {
             name = "$name (body)";
@@ skipping 655 matching lines @@
     methodInterceptionEnabled = true;
   }
 
   HGraph buildMethod(FunctionElement functionElement) {
     FunctionExpression function = functionElement.parseNode(compiler);
     openFunction(functionElement, function);
     function.body.accept(this);
     return closeFunction();
   }
 
+  HGraph buildLazyInitializer(VariableElement variable) {
+    HBasicBlock block = graph.addNewBlock();
+    open(graph.entry);
+    close(new HGoto()).addSuccessor(block);
+    open(block);
+    SendSet node = variable.parseNode(compiler);
+    Link<Node> link = node.arguments;
+    assert(!link.isEmpty() && link.tail.isEmpty());
+    visit(link.head);
+    close(new HReturn(pop())).addSuccessor(graph.exit);
+    graph.finalize();
+    return graph;
+  }
+
   /**
    * Returns the constructor body associated with the given constructor or
    * creates a new constructor body, if none can be found.
    *
    * Returns [:null:] if the constructor does not have a body.
    */
   ConstructorBodyElement getConstructorBody(FunctionElement constructor) {
     assert(constructor.kind === ElementKind.GENERATIVE_CONSTRUCTOR);
     if (constructor is SynthesizedConstructorElement) return null;
     FunctionExpression node = constructor.parseNode(compiler);
@@ skipping 171 matching lines @@
     // Call the JavaScript constructor with the fields as argument.
     List<HInstruction> constructorArguments = <HInstruction>[];
     classElement.forEachInstanceField(
         includeBackendMembers: true,
         includeSuperMembers: true,
         f: (ClassElement enclosingClass, Element member) {
       HInstruction value = fieldValues[member];
       if (value === null) {
         // The field has no value in the initializer list. Initialize it
         // with the declaration-site constant (if any).
-        Constant fieldValue = compiler.constantHandler.compileVariable(member);
+        Constant fieldValue = compiler.compileConstant(member);
         value = graph.addConstant(fieldValue);
       }
       constructorArguments.add(value);
     });
 
     HForeignNew newObject = new HForeignNew(classElement, constructorArguments);
     add(newObject);
     // Generate calls to the constructor bodies.
     for (int index = constructors.length - 1; index >= 0; index--) {
       FunctionElement constructor = constructors[index];
@@ skipping 696 matching lines @@
       add(target);
       List<HInstruction> inputs = <HInstruction>[target, receiver];
       push(new HInvokeInterceptor(selector, getterName, inputs, getter: true));
     } else {
       push(new HInvokeDynamicGetter(selector, null, getterName, receiver));
     }
   }
 
   void generateGetter(Send send, Element element) {
     if (Elements.isStaticOrTopLevelField(element)) {
+      Constant value;
       if (element.kind == ElementKind.FIELD && !element.isAssignable()) {

[kasperl, 2012/08/16 14:41:37]

isField?

[floitsch, 2012/08/16 22:52:33]

Done.

-        // A static final. Get its constant value and inline it.
-        Constant value = compiler.constantHandler.compileVariable(element);
+        // A static final or const. Get its constant value and inline it if
+        // the value can be compiled eagerly.
+        value = compiler.compileVariable(element);
+      }
+      if (value != null) {
         stack.add(graph.addConstant(value));
+      } else if (element.kind == ElementKind.FIELD &&
+                 compiler.isLazilyInitialized(element)) {
+        assert(element.kind == ElementKind.FIELD);

[kasperl, 2012/08/16 14:41:37]

Seems like a completely trivial assert given the condition.

[floitsch, 2012/08/16 22:52:33]

Done.

+        push(new HLazyStatic(element));
       } else {
         Selector selector = elements.getSelector(send);
         push(new HStatic(element));
         if (element.kind == ElementKind.GETTER) {
           push(new HInvokeStatic(selector, <HInstruction>[pop()]));
         }
       }
     } else if (Elements.isInstanceSend(send, elements)) {
       HInstruction receiver = generateInstanceSendReceiver(send);
       generateInstanceGetterWithCompiledReceiver(send, receiver);
@@ skipping 183 matching lines @@
   bool addStaticSendArgumentsToList(Selector selector,
                                     Link<Node> arguments,
                                     FunctionElement element,
                                     List<HInstruction> list) {
     HInstruction compileArgument(Node argument) {
       visit(argument);
       return pop();
     }
 
     HInstruction compileConstant(Element constantElement) {
-      Constant constant = compiler.compileVariable(constantElement);
+      Constant constant = compiler.compileConstant(constantElement);
       return graph.addConstant(constant);
     }
 
     return selector.addArgumentsToList(arguments,
                                        list,
                                        element,
                                        compileArgument,
                                        compileConstant,
                                        compiler);
   }
@@ skipping 1625 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;
   }
 }