Use JavaScript runtime semantics when constant folding.

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 139 matching lines @@
       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;
       HInstruction.idCounter = 0;
-      SsaBuilder builder = new SsaBuilder(this, work);
+      ConstantSystem constantSystem =
+          compiler.constantHandler.constantSystem;
+      SsaBuilder builder = new SsaBuilder(constantSystem, 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);
       }
@@ skipping 624 matching lines @@
       result.add(element);
     }
     return (result === null) ? const <LabelElement>[] : result;
   }
 }
 
 class SsaBuilder extends ResolvedVisitor implements Visitor {
   final SsaBuilderTask builder;
   final Interceptors interceptors;
   final WorkItem work;
+  final ConstantSystem constantSystem;
   bool methodInterceptionEnabled;
   HGraph graph;
   LocalsHandler localsHandler;
   HInstruction rethrowableException;
   Map<Element, HParameterValue> parameters;
 
   Map<TargetElement, JumpHandler> jumpTargets;
 
   /**
    * Variables stored in the current activation. These variables are
@@ skipping 10 matching lines @@
   HBasicBlock current;
   // The most recently opened block. Has the same value as [current] while
   // the block is open, but unlike [current], it isn't cleared when the current
   // block is closed.
   HBasicBlock lastOpenedBlock;
 
   LibraryElement get currentLibrary => work.element.getLibrary();
   Compiler get compiler => builder.compiler;
   CodeEmitterTask get emitter => builder.emitter;
 
-  SsaBuilder(SsaBuilderTask builder, WorkItem work)
+  SsaBuilder(this.constantSystem, SsaBuilderTask builder, WorkItem work)
     : this.builder = builder,
       this.work = work,
       interceptors = builder.interceptors,
       methodInterceptionEnabled = true,
       graph = new HGraph(),
       stack = new List<HInstruction>(),
       activationVariables = new Map<Element, HLocalValue>(),
       jumpTargets = new Map<TargetElement, JumpHandler>(),
       parameters = new Map<Element, HParameterValue>(),
       inliningStack = <InliningState>[],
@@ skipping 77 matching lines @@
                                                   compiledArguments);
     assert(succeeded);
 
     InliningState state =
         new InliningState(function, returnElement, elements, stack);
     inliningStack.add(state);
     stack = <HInstruction>[];
     returnElement = new Element(const SourceString("result"),
                                 ElementKind.VARIABLE,
                                 function);
-    localsHandler.updateLocal(returnElement, graph.addConstantNull());
+    Constant constantNull = constantSystem.createNull();
+    localsHandler.updateLocal(returnElement, graph.addConstant(constantNull));
     elements = compiler.enqueuer.resolution.getCachedElements(function);
     FunctionSignature signature = function.computeSignature(compiler);
     int index = 0;
     signature.forEachParameter((Element parameter) {
       HInstruction argument = compiledArguments[index++];
       localsHandler.updateLocal(parameter, argument);
       potentiallyCheckType(argument, parameter);
     });
     return state;
   }
@@ skipping 161 matching lines @@
                               Map<Element, HInstruction> fieldValues) {
     classElement.forEachInstanceField(
         includeBackendMembers: true,
         includeSuperMembers: false,
         f: (ClassElement enclosingClass, Element member) {
       TreeElements definitions = compiler.analyzeElement(member);
       Node node = member.parseNode(compiler);
       SendSet assignment = node.asSendSet();
       HInstruction value;
       if (assignment === null) {
-        value = graph.addConstantNull();
+        value = graph.addConstant(constantSystem.createNull());
       } else {
         Node right = assignment.arguments.head;
         TreeElements savedElements = elements;
         elements = definitions;
         right.accept(this);
         elements = savedElements;
         value = pop();
       }
       fieldValues[member] = value;
     });
@@ skipping 461 matching lines @@
       Node initializer = node.initializer;
       if (initializer !== null) {
         visit(initializer);
         if (initializer.asExpression() !== null) {
           pop();
         }
       }
     }
     HInstruction buildCondition() {
       if (node.condition === null) {
-        return graph.addConstantBool(true);
+        return graph.addConstant(constantSystem.createBool(true));
       }
       visit(node.condition);
       return popBoolified();
     }
     void buildUpdate() {
       for (Expression expression in node.update) {
         visit(expression);
         assert(!isAborted());
         // The result of the update instruction isn't used, and can just
         // be dropped.
@@ skipping 167 matching lines @@
     assert(node.argumentsNode is Prefix);
     visit(node.receiver);
     HNot not = new HNot(popBoolified());
     pushWithPosition(not, node);
   }
 
   void visitUnary(Send node, Operator op) {
     String value = op.source.stringValue;
     if (value === '?') {
       // TODO(ahe): Implement argument definition test.
-      stack.add(graph.addConstantBool(true));
+      stack.add(graph.addConstant(constantSystem.createBool(true)));
       return;
     }
     assert(node.argumentsNode is Prefix);
     visit(node.receiver);
     assert(op.token.kind !== PLUS_TOKEN);
     HInstruction operand = pop();
 
     HInstruction target =
         new HStatic(interceptors.getPrefixOperatorInterceptor(op));
     add(target);
     HInvokeUnary result;
     switch (value) {
       case "-": result = new HNegate(target, operand); break;
       case "~": result = new HBitNot(target, operand); break;
       default:
         compiler.internalError('Unexpected unary operator: $value.', node: op);
         break;
     }
     // See if we can constant-fold right away. This avoids rewrites later on.
     if (operand is HConstant) {
       HConstant constant = operand;
-      Constant folded = result.operation.fold(constant.constant);
+      Constant folded =
+          result.operation(constantSystem).fold(constant.constant);
       if (folded !== null) {
         stack.add(graph.addConstant(folded));
         return;
       }
     }
     pushWithPosition(result, node);
   }
 
   void visitBinary(HInstruction left, Operator op, HInstruction right) {
     Element element = interceptors.getOperatorInterceptor(op);
@@ skipping 262 matching lines @@
       HInstruction typeInfo = null;
       if (compiler.codegenWorld.rti.hasTypeArguments(type)) {
         pushInvokeHelper1(interceptors.getGetRuntimeTypeInfo(), expression);
         typeInfo = pop();
       }
       if (type.element.kind === ElementKind.TYPE_VARIABLE) {
         // TODO(karlklose): We emulate the behavior of the old frog
         // compiler and answer true to any is check involving a type variable
         // -- both is T and is !T -- until we have a proper implementation of
         // reified generics.
-        stack.add(graph.addConstantBool(true));
+        stack.add(graph.addConstant(constantSystem.createBool(true)));
       } else {
         HInstruction instruction;
         if (typeInfo !== null) {
           instruction = new HIs.withTypeInfoCall(type, expression, typeInfo);
         } else {
           instruction = new HIs(type, expression);
         }
         if (isNot) {
           add(instruction);
           instruction = new HNot(instruction);
@@ skipping 308 matching lines @@
   generateSuperNoSuchMethodSend(Send node) {
     ClassElement cls = work.element.getEnclosingClass();
     Element element = cls.lookupSuperMember(Compiler.NO_SUCH_METHOD);
     HStatic target = new HStatic(element);
     add(target);
     HInstruction self = localsHandler.readThis();
     Identifier identifier = node.selector.asIdentifier();
     String name = identifier.source.slowToString();
     // TODO(ahe): Add the arguments to this list.
     push(new HLiteralList([]));
+    Constant nameConstant =
+        constantSystem.createString(new DartString.literal(name), node);
     var inputs = <HInstruction>[
         target,
         self,
-        graph.addConstantString(new DartString.literal(name), node),
+        graph.addConstant(nameConstant),
         pop()];
     push(new HInvokeSuper(inputs));
   }
 
   visitSend(Send node) {
     Element element = elements[node];
     if (element !== null && element === work.element) {
       graph.isRecursiveMethod = true;
     }
     super.visitSend(node);
@@ skipping 47 matching lines @@
         add(foreign);
         return foreign;
       } else {
         // TODO(ngeoffray): Match the VM behavior and throw an
         // exception at runtime.
         compiler.cancel('Unimplemented unresolved type variable',
                         node: currentNode);
       }
     } else {
       // The type variable is a type (e.g. int).
-      return graph.addConstantString(
-          new LiteralDartString('$argument'), currentNode);
+      return graph.addConstant(
+          constantSystem.createString(new LiteralDartString('$argument'),
+                                         currentNode));
     }
   }
 
   visitNewSend(Send node) {
     computeType(element) {
       Element originalElement = elements[node];
       if (originalElement.getEnclosingClass() === compiler.listClass) {
         if (node.arguments.isEmpty()) {
           return HType.EXTENDABLE_ARRAY;
         } else {
@@ skipping 33 matching lines @@
 
     HType elementType = computeType(constructor);
     HInstruction newInstance = new HInvokeStatic(inputs, elementType);
     pushWithPosition(newInstance, node);
   }
 
   visitStaticSend(Send node) {
     Selector selector = elements.getSelector(node);
     Element element = elements[node];
     if (element === compiler.assertMethod && !compiler.enableUserAssertions) {
-      stack.add(graph.addConstantNull());
+      stack.add(graph.addConstant(constantSystem.createNull()));
       return;
     }
     compiler.ensure(element.kind !== ElementKind.GENERATIVE_CONSTRUCTOR);
 
     if (tryInlineMethod(element, selector, node.arguments)) return;
 
     HInstruction target = new HStatic(element);
     add(target);
     var inputs = <HInstruction>[];
     inputs.add(target);
@@ skipping 42 matching lines @@
       if (selector.receiver is TypeAnnotation) {
         return selector.receiver;
       }
     } else {
       compiler.internalError("malformed send in new expression");
     }
   }
 
   void generateRuntimeError(Node node, String message) {
     DartString messageObject = new DartString.literal(message);
-    HInstruction errorMessage = graph.addConstantString(messageObject, node);
+    Constant messageConstant =
+        constantSystem.createString(messageObject, node);
+    HInstruction errorMessage = graph.addConstant(messageConstant);
     Element helper = interceptors.getThrowRuntimeError();
     pushInvokeHelper1(helper, errorMessage);
   }
 
   visitNewExpression(NewExpression node) {
     Element element = elements[node.send];
     if (element != null && element.isErroneous()) {
       ErroneousElement error = element;
       Message message = error.errorMessage;
       if (message.kind === MessageKind.CANNOT_FIND_CONSTRUCTOR) {
         Element helper =
             compiler.findHelper(const SourceString('throwNoSuchMethod'));
         DartString receiverLiteral = new DartString.literal('');
-        HInstruction receiver = graph.addConstantString(receiverLiteral, node);
+        Constant receiverConstant =
+            constantSystem.createString(receiverLiteral, node);
+        HInstruction receiver = graph.addConstant(receiverConstant);
         String constructorName = 'constructor ${message.arguments[0]}';
         DartString nameLiteral = new DartString.literal(constructorName);
-        HInstruction name = graph.addConstantString(nameLiteral, node.send);
+        Constant nameConstant =
+            constantSystem.createString(nameLiteral, node.send);
+        HInstruction name = graph.addConstant(nameConstant);
         List<HInstruction> inputs = <HInstruction>[];
         node.send.arguments.forEach((argumentNode) {
           visit(argumentNode);
           HInstruction value = pop();
           inputs.add(value);
         });
         HInstruction arguments = new HLiteralList(inputs);
         add(arguments);
         pushInvokeHelper3(helper, receiver, name, arguments);
       } else if (message.kind === MessageKind.CANNOT_RESOLVE) {
@@ skipping 48 matching lines @@
           HInstruction index;
           bool isCompoundAssignment = op.source.stringValue.endsWith('=');
           // Compound assignments are considered as being prefix.
           bool isPrefix = !node.isPostfix;
           Element getter = elements[node.selector];
           if (isCompoundAssignment) {
             value = pop();
             index = pop();
           } else {
             index = pop();
-            value = graph.addConstantInt(1);
+            value = graph.addConstant(constantSystem.createInt(1));
           }
           HStatic indexMethod = new HStatic(interceptors.getIndexInterceptor());
           add(indexMethod);
           HInstruction left = new HIndex(indexMethod, receiver, index);
           add(left);
           Element opElement = elements[op];
           visitBinary(left, op, value);
           value = pop();
           HInstruction assign = new HIndexAssign(
               target, receiver, index, value);
@@ skipping 29 matching lines @@
         generateInstanceGetterWithCompiledReceiver(node, receiver);
       } else {
         generateGetter(node, elements[node.selector]);
       }
       HInstruction left = pop();
       HInstruction right;
       if (isCompoundAssignment) {
         visit(node.argumentsNode);
         right = pop();
       } else {
-        right = graph.addConstantInt(1);
+        right = graph.addConstant(constantSystem.createInt(1));
       }
       visitBinary(left, op, right);
       HInstruction operation = pop();
       assert(operation !== null);
       if (Elements.isInstanceSend(node, elements)) {
         assert(receiver !== null);
         generateInstanceSetterWithCompiledReceiver(node, receiver, operation);
       } else {
         assert(receiver === null);
         generateSetter(node, element, operation);
       }
       if (!isPrefix) {
         pop();
         stack.add(left);
       }
     }
   }
 
   void visitLiteralInt(LiteralInt node) {
-    stack.add(graph.addConstantInt(node.value));
+    stack.add(graph.addConstant(constantSystem.createInt(node.value)));
   }
 
   void visitLiteralDouble(LiteralDouble node) {
-    stack.add(graph.addConstantDouble(node.value));
+    stack.add(graph.addConstant(constantSystem.createDouble(node.value)));
   }
 
   void visitLiteralBool(LiteralBool node) {
-    stack.add(graph.addConstantBool(node.value));
+    stack.add(graph.addConstant(constantSystem.createBool(node.value)));
   }
 
   void visitLiteralString(LiteralString node) {
-    stack.add(graph.addConstantString(node.dartString, node));
+    Constant constant = constantSystem.createString(node.dartString, node);
+    stack.add(graph.addConstant(constant));
   }
 
   void visitStringJuxtaposition(StringJuxtaposition node) {
     if (!node.isInterpolation) {
       // This is a simple string with no interpolations.
-      stack.add(graph.addConstantString(node.dartString, node));
+      Constant constant = constantSystem.createString(node.dartString, node);
+      stack.add(graph.addConstant(constant));
       return;
     }
     StringBuilderVisitor stringBuilder = new StringBuilderVisitor(this, node);
     stringBuilder.visit(node);
     stack.add(stringBuilder.result);
   }
 
   void visitLiteralNull(LiteralNull node) {
-    stack.add(graph.addConstantNull());
+    stack.add(graph.addConstant(constantSystem.createNull()));
   }
 
   visitNodeList(NodeList node) {
     for (Link<Node> link = node.nodes; !link.isEmpty(); link = link.tail) {
       if (isAborted()) {
         compiler.reportWarning(link.head, 'dead code');
       } else {
         visit(link.head);
       }
     }
@@ skipping 19 matching lines @@
     dup();
   }
 
   visitReturn(Return node) {
     if (node.getBeginToken().stringValue === 'native') {
       native.handleSsaNative(this, node.expression);
       return;
     }
     HInstruction value;
     if (node.expression === null) {
-      value = graph.addConstantNull();
+      value = graph.addConstant(constantSystem.createNull());
     } else {
       visit(node.expression);
       value = pop();
     }
     if (!inliningStack.isEmpty()) {
       localsHandler.updateLocal(returnElement, value);
     } else {
       close(attachPosition(new HReturn(value), node)).addSuccessor(graph.exit);
     }
   }
 
   visitThrow(Throw node) {
     if (node.expression === null) {
       HInstruction exception = rethrowableException;
       if (exception === null) {
-        exception = graph.addConstantNull();
+        exception = graph.addConstant(constantSystem.createNull());
         compiler.reportError(node,
                              'throw without expression outside catch block');
       }
       close(new HThrow(exception, isRethrow: true));
     } else {
       visit(node.expression);
       close(new HThrow(pop()));
     }
   }
 
   visitTypeAnnotation(TypeAnnotation node) {
     compiler.internalError('visiting type annotation in SSA builder',
                            node: node);
   }
 
   visitVariableDefinitions(VariableDefinitions node) {
     for (Link<Node> link = node.definitions.nodes;
          !link.isEmpty();
          link = link.tail) {
       Node definition = link.head;
       if (definition is Identifier) {
-        HInstruction initialValue = graph.addConstantNull();
+        HInstruction initialValue =
+            graph.addConstant(constantSystem.createNull());
         localsHandler.updateLocal(elements[definition], initialValue);
       } else {
         assert(definition is SendSet);
         visitSendSet(definition);
         pop();  // Discard value.
       }
     }
   }
 
   visitLiteralList(LiteralList node) {
@@ skipping 577 matching lines @@
             compiler.cancel('On with unresolved type',
                             node: catchBlock.type);
           }
           HInstruction condition = new HIs(type, unwrappedException);
           push(condition);
         }
         else {
           VariableDefinitions declaration = catchBlock.formals.nodes.head;
           HInstruction condition = null;
           if (declaration.type == null) {
-            condition = graph.addConstantBool(true);
+            condition = graph.addConstant(constantSystem.createBool(true));
             stack.add(condition);
           } else {
             // TODO(aprelev@gmail.com): Once old catch syntax is removed
             // "if" condition above and this "else" branch should be deleted as
             // type of declared variable won't matter for the catch
             // condition
             DartType type = elements.getType(declaration.type);
             if (type == null) {
               compiler.cancel('Catch with unresolved type', node: catchBlock);
             }
@@ skipping 90 matching lines @@
     if (element === builder.compiler.intClass) return HType.INTEGER;
     if (element === builder.compiler.listClass) return HType.READABLE_ARRAY;
     if (element === builder.compiler.nullClass) return HType.NULL;
     if (element === builder.compiler.stringClass) return HType.STRING;
     return HType.UNKNOWN;
   }
 
   /** HACK HACK HACK */
   void hackAroundPossiblyAbortingBody(Node statement, void body()) {
     visitCondition() {
-      stack.add(graph.addConstantBool(true));
+      stack.add(graph.addConstant(constantSystem.createBool(true)));
     }
     buildBody() {
       // TODO(lrn): Make sure to take continue into account.
       body();
     }
     handleIf(statement, visitCondition, buildBody, null);
   }
 }
 
 /**
@@ skipping 267 matching lines @@
         builder.push(new HNot(builder.pop()));
       }
     }
 
     void visitThen() {
       right();
       boolifiedRight = builder.popBoolified();
     }
 
     handleIf(visitCondition, visitThen, null);
+    HConstant notIsAnd =
+        builder.graph.addConstant(builder.constantSystem.createBool(!isAnd));
     HPhi result = new HPhi.manyInputs(null,
-        <HInstruction>[boolifiedRight, builder.graph.addConstantBool(!isAnd)]);
+                                      <HInstruction>[boolifiedRight, notIsAnd]);
     builder.current.addPhi(result);
     builder.stack.add(result);
   }
 
   void handleLogicalAndOrWithLeftNode(Node left,
                                       void visitRight(),
                                       [bool isAnd]) {
     // This method is similar to [handleLogicalAndOr] but optimizes the case
     // where left is a logical "and" or logical "or".
     //
@@ skipping 66 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;
   }
 }