Revert "Move dart2js from sdk/lib/_internal/compiler to pkg/compiler"

pkg/compiler/lib/src/ssa/codegen.dart

Index: pkg/compiler/lib/src/ssa/codegen.dart
diff --git a/pkg/compiler/lib/src/ssa/codegen.dart b/pkg/compiler/lib/src/ssa/codegen.dart
deleted file mode 100644
index f67fe0030254043ea8bd3846ff4f2304649a6cf7..0000000000000000000000000000000000000000
--- a/pkg/compiler/lib/src/ssa/codegen.dart
+++ /dev/null
@@ -1,2722 +0,0 @@
-// 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;
-
-class SsaCodeGeneratorTask extends CompilerTask {
-
-  final JavaScriptBackend backend;
-
-  SsaCodeGeneratorTask(JavaScriptBackend backend)
-      : this.backend = backend,
-        super(backend.compiler);
-  String get name => 'SSA code generator';
-  NativeEmitter get nativeEmitter => backend.emitter.nativeEmitter;
-
-
-  js.Node attachPosition(js.Node node, AstElement element) {
-    // TODO(sra): Attaching positions might be cleaner if the source position
-    // was on a wrapping node.
-    SourceFile sourceFile = sourceFileOfElement(element);
-    String name = element.name;
-    AstElement implementation = element.implementation;
-    ast.Node expression = implementation.node;
-    Token beginToken;
-    Token endToken;
-    if (expression == null) {
-      // Synthesized node. Use the enclosing element for the location.
-      beginToken = endToken = element.position;
-    } else {
-      beginToken = expression.getBeginToken();
-      endToken = expression.getEndToken();
-    }
-    // TODO(podivilov): find the right sourceFile here and remove offset
-    // checks below.
-    var sourcePosition, endSourcePosition;
-    if (beginToken.charOffset < sourceFile.length) {
-      sourcePosition =
-          new TokenSourceFileLocation(sourceFile, beginToken, name);
-    }
-    if (endToken.charOffset < sourceFile.length) {
-      endSourcePosition =
-          new TokenSourceFileLocation(sourceFile, endToken, name);
-    }
-    return node.withPosition(sourcePosition, endSourcePosition);
-  }
-
-  SourceFile sourceFileOfElement(Element element) {
-    return element.implementation.compilationUnit.script.file;
-  }
-
-  js.Fun buildJavaScriptFunction(FunctionElement element,
-                                 List<js.Parameter> parameters,
-                                 js.Block body) {
-    return attachPosition(new js.Fun(parameters, body), element);
-  }
-
-  js.Expression generateCode(CodegenWorkItem work, HGraph graph) {
-    if (work.element.isField) {
-      return generateLazyInitializer(work, graph);
-    } else {
-      return generateMethod(work, graph);
-    }
-  }
-
-  js.Expression generateLazyInitializer(work, graph) {
-    return measure(() {
-      compiler.tracer.traceGraph("codegen", graph);
-      SsaCodeGenerator codegen = new SsaCodeGenerator(backend, work);
-      codegen.visitGraph(graph);
-      return new js.Fun(codegen.parameters,
-          attachPosition(codegen.body, work.element));
-    });
-  }
-
-  js.Expression generateMethod(CodegenWorkItem work, HGraph graph) {
-    return measure(() {
-      SsaCodeGenerator codegen = new SsaCodeGenerator(backend, work);
-      codegen.visitGraph(graph);
-      compiler.tracer.traceGraph("codegen", graph);
-      FunctionElement element = work.element;
-      return buildJavaScriptFunction(element, codegen.parameters, codegen.body);
-    });
-  }
-}
-
-typedef void EntityAction(Entity element);
-
-class SsaCodeGenerator implements HVisitor, HBlockInformationVisitor {
-  /**
-   * Returned by [expressionType] to tell how code can be generated for
-   * a subgraph.
-   * - [TYPE_STATEMENT] means that the graph must be generated as a statement,
-   * which is always possible.
-   * - [TYPE_EXPRESSION] means that the graph can be generated as an expression,
-   * or possibly several comma-separated expressions.
-   * - [TYPE_DECLARATION] means that the graph can be generated as an
-   * expression, and that it only generates expressions of the form
-   *   variable = expression
-   * which are also valid as parts of a "var" declaration.
-   */
-  static const int TYPE_STATEMENT = 0;
-  static const int TYPE_EXPRESSION = 1;
-  static const int TYPE_DECLARATION = 2;
-
-  /**
-   * Whether we are currently generating expressions instead of statements.
-   * This includes declarations, which are generated as expressions.
-   */
-  bool isGeneratingExpression = false;
-
-  final JavaScriptBackend backend;
-  final CodegenWorkItem work;
-
-  final Set<HInstruction> generateAtUseSite;
-  final Set<HInstruction> controlFlowOperators;
-  final Map<Entity, EntityAction> breakAction;
-  final Map<Entity, EntityAction> continueAction;
-  final List<js.Parameter> parameters;
-
-  js.Block currentContainer;
-  js.Block get body => currentContainer;
-  List<js.Expression> expressionStack;
-  List<js.Block> oldContainerStack;
-
-  /**
-   * Contains the names of the instructions, as well as the parallel
-   * copies to perform on block transitioning.
-   */
-  VariableNames variableNames;
-  bool shouldGroupVarDeclarations = false;
-
-  /**
-   * While generating expressions, we can't insert variable declarations.
-   * Instead we declare them at the start of the function.  When minifying
-   * we do this most of the time, because it reduces the size unless there
-   * is only one variable.
-   */
-  final Set<String> collectedVariableDeclarations;
-
-  /**
-   * Set of variables and parameters that have already been declared.
-   */
-  final Set<String> declaredLocals;
-
-  HGraph currentGraph;
-
-  // Records a block-information that is being handled specially.
-  // Used to break bad recursion.
-  HBlockInformation currentBlockInformation;
-  // The subgraph is used to delimit traversal for some constructions, e.g.,
-  // if branches.
-  SubGraph subGraph;
-
-  SsaCodeGenerator(this.backend, CodegenWorkItem work)
-    : this.work = work,
-      declaredLocals = new Set<String>(),
-      collectedVariableDeclarations = new Set<String>(),
-      currentContainer = new js.Block.empty(),
-      parameters = <js.Parameter>[],
-      expressionStack = <js.Expression>[],
-      oldContainerStack = <js.Block>[],
-      generateAtUseSite = new Set<HInstruction>(),
-      controlFlowOperators = new Set<HInstruction>(),
-      breakAction = new Map<Entity, EntityAction>(),
-      continueAction = new Map<Entity, EntityAction>();
-
-  Compiler get compiler => backend.compiler;
-  NativeEmitter get nativeEmitter => backend.emitter.nativeEmitter;
-  CodegenRegistry get registry => work.registry;
-
-  bool isGenerateAtUseSite(HInstruction instruction) {
-    return generateAtUseSite.contains(instruction);
-  }
-
-  bool hasNonBitOpUser(HInstruction instruction, Set<HPhi> phiSet) {
-    for (HInstruction user in instruction.usedBy) {
-      if (user is HPhi) {
-        if (!phiSet.contains(user)) {
-          phiSet.add(user);
-          if (hasNonBitOpUser(user, phiSet)) return true;
-        }
-      } else if (user is! HBitNot && user is! HBinaryBitOp) {
-        return true;
-      }
-    }
-    return false;
-  }
-
-  bool requiresUintConversion(instruction) {
-    if (instruction.isUInt31(compiler)) return false;
-    // If the result of a bit-operation is only used by other bit
-    // operations, we do not have to convert to an unsigned integer.
-    return hasNonBitOpUser(instruction, new Set<HPhi>());
-  }
-
-  /**
-   * If the [instruction] is not `null` it will be used to attach the position
-   * to the [statement].
-   */
-  void pushStatement(js.Statement statement, [HInstruction instruction]) {
-    assert(expressionStack.isEmpty);
-    if (instruction != null) {
-      statement = attachLocation(statement, instruction);
-    }
-    currentContainer.statements.add(statement);
-  }
-
-  void insertStatementAtStart(js.Statement statement) {
-    currentContainer.statements.insert(0, statement);
-  }
-
-  /**
-   * If the [instruction] is not `null` it will be used to attach the position
-   * to the [expression].
-   */
-  pushExpressionAsStatement(js.Expression expression,
-                            [HInstruction instruction]) {
-    pushStatement(new js.ExpressionStatement(expression), instruction);
-  }
-
-  /**
-   * If the [instruction] is not `null` it will be used to attach the position
-   * to the [expression].
-   */
-  push(js.Expression expression, [HInstruction instruction]) {
-    if (instruction != null) {
-      expression = attachLocation(expression, instruction);
-    }
-    expressionStack.add(expression);
-  }
-
-  js.Expression pop() {
-    return expressionStack.removeLast();
-  }
-
-  attachLocationToLast(HInstruction instruction) {
-    int index = expressionStack.length - 1;
-    expressionStack[index] =
-        attachLocation(expressionStack[index], instruction);
-  }
-
-  js.Node attachLocation(js.Node jsNode, HInstruction instruction) {
-    return jsNode.withLocation(instruction.sourcePosition);
-  }
-
-  js.Node attachLocationRange(js.Node jsNode,
-                              SourceFileLocation sourcePosition,
-                              SourceFileLocation endSourcePosition) {
-    return jsNode.withPosition(sourcePosition, endSourcePosition);
-  }
-
-  void preGenerateMethod(HGraph graph) {
-    new SsaInstructionSelection(compiler).visitGraph(graph);
-    new SsaTypeKnownRemover().visitGraph(graph);
-    new SsaInstructionMerger(generateAtUseSite, compiler).visitGraph(graph);
-    new SsaConditionMerger(
-        generateAtUseSite, controlFlowOperators).visitGraph(graph);
-    SsaLiveIntervalBuilder intervalBuilder = new SsaLiveIntervalBuilder(
-        compiler, generateAtUseSite, controlFlowOperators);
-    intervalBuilder.visitGraph(graph);
-    SsaVariableAllocator allocator = new SsaVariableAllocator(
-        compiler,
-        intervalBuilder.liveInstructions,
-        intervalBuilder.liveIntervals,
-        generateAtUseSite);
-    allocator.visitGraph(graph);
-    variableNames = allocator.names;
-    shouldGroupVarDeclarations = allocator.names.numberOfVariables > 1;
-  }
-
-  void handleDelayedVariableDeclarations() {
-    // If we have only one variable declaration and the first statement is an
-    // assignment to that variable then we can merge the two.  We count the
-    // number of variables in the variable allocator to try to avoid this issue,
-    // but it sometimes happens that the variable allocator introduces a
-    // temporary variable that it later eliminates.
-    if (!collectedVariableDeclarations.isEmpty) {
-      if (collectedVariableDeclarations.length == 1 &&
-          currentContainer.statements.length >= 1 &&
-          currentContainer.statements[0] is js.ExpressionStatement) {
-        String name = collectedVariableDeclarations.first;
-        js.ExpressionStatement statement = currentContainer.statements[0];
-        if (statement.expression is js.Assignment) {
-          js.Assignment assignment = statement.expression;
-          if (!assignment.isCompound &&
-              assignment.leftHandSide is js.VariableReference) {
-            js.VariableReference variableReference = assignment.leftHandSide;
-            if (variableReference.name == name) {
-              js.VariableDeclaration decl = new js.VariableDeclaration(name);
-              js.VariableInitialization initialization =
-                  new js.VariableInitialization(decl, assignment.value);
-              currentContainer.statements[0] = new js.ExpressionStatement(
-                  new js.VariableDeclarationList([initialization]));
-              return;
-            }
-          }
-        }
-      }
-      // If we can't merge the declaration with the first assignment then we
-      // just do it with a new var z,y,x; statement.
-      List<js.VariableInitialization> declarations =
-          <js.VariableInitialization>[];
-      collectedVariableDeclarations.forEach((String name) {
-        declarations.add(new js.VariableInitialization(
-            new js.VariableDeclaration(name), null));
-      });
-      var declarationList = new js.VariableDeclarationList(declarations);
-      insertStatementAtStart(new js.ExpressionStatement(declarationList));
-    }
-  }
-
-  visitGraph(HGraph graph) {
-    preGenerateMethod(graph);
-    currentGraph = graph;
-    subGraph = new SubGraph(graph.entry, graph.exit);
-    visitBasicBlock(graph.entry);
-    handleDelayedVariableDeclarations();
-  }
-
-  void visitSubGraph(SubGraph newSubGraph) {
-    SubGraph oldSubGraph = subGraph;
-    subGraph = newSubGraph;
-    visitBasicBlock(subGraph.start);
-    subGraph = oldSubGraph;
-  }
-
-  /**
-   * Check whether a sub-graph can be generated as an expression, or even
-   * as a declaration, or if it has to fall back to being generated as
-   * a statement.
-   * Expressions are anything that doesn't generate control flow constructs.
-   * Declarations must only generate assignments on the form "id = expression",
-   * and not, e.g., expressions where the value isn't assigned, or where it's
-   * assigned to something that's not a simple variable.
-   */
-  int expressionType(HExpressionInformation info) {
-    // The only HExpressionInformation used as part of a HBlockInformation is
-    // current HSubExpressionBlockInformation, so it's the only one reaching
-    // here. If we start using the other HExpressionInformation types too,
-    // this code should be generalized.
-    assert(info is HSubExpressionBlockInformation);
-    HSubExpressionBlockInformation expressionInfo = info;
-    SubGraph limits = expressionInfo.subExpression;
-
-    // Start assuming that we can generate declarations. If we find a
-    // counter-example, we degrade our assumption to either expression or
-    // statement, and in the latter case, we can return immediately since
-    // it can't get any worse. E.g., a function call where the return value
-    // isn't used can't be in a declaration.
-    int result = TYPE_DECLARATION;
-    HBasicBlock basicBlock = limits.start;
-    do {
-      HInstruction current = basicBlock.first;
-      while (current != basicBlock.last) {
-        // E.g, bounds check.
-        if (current.isControlFlow()) {
-          return TYPE_STATEMENT;
-        }
-        // HFieldSet generates code on the form x.y = ..., which isn't
-        // valid in a declaration, but it also always have no uses, so
-        // it's caught by that test too.
-        assert(current is! HFieldSet || current.usedBy.isEmpty);
-        if (current.usedBy.isEmpty) {
-          result = TYPE_EXPRESSION;
-        }
-        current = current.next;
-      }
-      if (current is HGoto) {
-        basicBlock = basicBlock.successors[0];
-      } else if (current is HConditionalBranch) {
-        if (generateAtUseSite.contains(current)) {
-          // Short-circuit control flow operator trickery.
-          // Check the second half, which will continue into the join.
-          // (The first half is [inputs[0]], the second half is [successors[0]],
-          // and [successors[1]] is the join-block).
-          basicBlock = basicBlock.successors[0];
-        } else {
-          // We allow an expression to end on an HIf (a condition expression).
-          return identical(basicBlock, limits.end) ? result : TYPE_STATEMENT;
-        }
-      } else {
-        // Expression-incompatible control flow.
-        return TYPE_STATEMENT;
-      }
-    } while (limits.contains(basicBlock));
-    return result;
-  }
-
-  bool isJSExpression(HExpressionInformation info) {
-    return !identical(expressionType(info), TYPE_STATEMENT);
-  }
-
-  bool isJSCondition(HExpressionInformation info) {
-    HSubExpressionBlockInformation graph = info;
-    SubExpression limits = graph.subExpression;
-    return !identical(expressionType(info), TYPE_STATEMENT) &&
-       (limits.end.last is HConditionalBranch);
-  }
-
-  /**
-   * Generate statements from block information.
-   * If the block information contains expressions, generate only
-   * assignments, and if it ends in a conditional branch, don't generate
-   * the condition.
-   */
-  void generateStatements(HBlockInformation block) {
-    if (block is HStatementInformation) {
-      block.accept(this);
-    } else {
-      HSubExpressionBlockInformation expression = block;
-      visitSubGraph(expression.subExpression);
-    }
-  }
-
-  js.Block generateStatementsInNewBlock(HBlockInformation block) {
-    js.Block result = new js.Block.empty();
-    js.Block oldContainer = currentContainer;
-    currentContainer = result;
-    generateStatements(block);
-    currentContainer = oldContainer;
-    return result;
-  }
-
-  /**
-   * If the [block] only contains one statement returns that statement. If the
-   * that statement itself is a block, recursively calls this method.
-   *
-   * If the block is empty, returns a new instance of [js.NOP].
-   */
-  js.Statement unwrapStatement(js.Block block) {
-    int len = block.statements.length;
-    if (len == 0) return new js.EmptyStatement();
-    if (len == 1) {
-      js.Statement result = block.statements[0];
-      if (result is ast.Block) return unwrapStatement(result);
-      return result;
-    }
-    return block;
-  }
-
-  /**
-   * Generate expressions from block information.
-   */
-  js.Expression generateExpression(HExpressionInformation expression) {
-    // Currently we only handle sub-expression graphs.
-    assert(expression is HSubExpressionBlockInformation);
-
-    bool oldIsGeneratingExpression = isGeneratingExpression;
-    isGeneratingExpression = true;
-    List<js.Expression> oldExpressionStack = expressionStack;
-    List<js.Expression> sequenceElements = <js.Expression>[];
-    expressionStack = sequenceElements;
-    HSubExpressionBlockInformation expressionSubGraph = expression;
-    visitSubGraph(expressionSubGraph.subExpression);
-    expressionStack = oldExpressionStack;
-    isGeneratingExpression = oldIsGeneratingExpression;
-    if (sequenceElements.isEmpty) {
-      // Happens when the initializer, condition or update of a loop is empty.
-      return null;
-    } else if (sequenceElements.length == 1) {
-      return sequenceElements[0];
-    } else {
-      js.Expression result = sequenceElements.removeLast();
-      while (sequenceElements.isNotEmpty) {
-        result = new js.Binary(',', sequenceElements.removeLast(), result);
-      }
-      return result;
-    }
-  }
-
-  /**
-    * Only visits the arguments starting at inputs[HInvoke.ARGUMENTS_OFFSET].
-    */
-  List<js.Expression> visitArguments(List<HInstruction> inputs,
-                                     {int start: HInvoke.ARGUMENTS_OFFSET}) {
-    assert(inputs.length >= start);
-    List<js.Expression> result = new List<js.Expression>(inputs.length - start);
-    for (int i = start; i < inputs.length; i++) {
-      use(inputs[i]);
-      result[i - start] = pop();
-    }
-    return result;
-  }
-
-  bool isVariableDeclared(String variableName) {
-    return declaredLocals.contains(variableName) ||
-        collectedVariableDeclarations.contains(variableName);
-  }
-
-  js.Expression generateExpressionAssignment(String variableName,
-                                             js.Expression value) {
-    if (value is js.Binary) {
-      js.Binary binary = value;
-      String op = binary.op;
-      if (op == '+' || op == '-' || op == '/' || op == '*' || op == '%' ||
-          op == '^' || op == '&' || op == '|') {
-        if (binary.left is js.VariableUse &&
-            (binary.left as js.VariableUse).name == variableName) {
-          // We know now, that we can shorten x = x + y into x += y.
-          // Also check for the shortcut where y equals 1: x++ and x--.
-          if ((op == '+' || op == '-') &&
-              binary.right is js.LiteralNumber &&
-              (binary.right as js.LiteralNumber).value == "1") {
-            return new js.Prefix(op == '+' ? '++' : '--', binary.left);
-          }
-          return new js.Assignment.compound(binary.left, op, binary.right);
-        }
-      }
-    }
-    return new js.Assignment(new js.VariableUse(variableName), value);
-  }
-
-  void assignVariable(String variableName, js.Expression value) {
-    if (isGeneratingExpression) {
-      // If we are in an expression then we can't declare the variable here.
-      // We have no choice, but to use it and then declare it separately.
-      if (!isVariableDeclared(variableName)) {
-        collectedVariableDeclarations.add(variableName);
-      }
-      push(generateExpressionAssignment(variableName, value));
-      // Otherwise if we are trying to declare inline and we are in a statement
-      // then we declare (unless it was already declared).
-    } else if (!shouldGroupVarDeclarations &&
-               !declaredLocals.contains(variableName)) {
-      // It may be necessary to remove it from the ones to be declared later.
-      collectedVariableDeclarations.remove(variableName);
-      declaredLocals.add(variableName);
-      js.VariableDeclaration decl = new js.VariableDeclaration(variableName);
-      js.VariableInitialization initialization =
-          new js.VariableInitialization(decl, value);
-
-      pushExpressionAsStatement(new js.VariableDeclarationList(
-          <js.VariableInitialization>[initialization]));
-    } else {
-      // Otherwise we are just going to use it.  If we have not already declared
-      // it then we make sure we will declare it later.
-      if (!declaredLocals.contains(variableName)) {
-        collectedVariableDeclarations.add(variableName);
-      }
-      pushExpressionAsStatement(
-          generateExpressionAssignment(variableName, value));
-    }
-  }
-
-  void define(HInstruction instruction) {
-    // For simple type checks like i = intTypeCheck(i), we don't have to
-    // emit an assignment, because the intTypeCheck just returns its
-    // argument.
-    bool needsAssignment = true;
-    if (instruction is HTypeConversion) {
-      HTypeConversion typeConversion = instruction;
-      String inputName = variableNames.getName(typeConversion.checkedInput);
-      if (variableNames.getName(instruction) == inputName) {
-        needsAssignment = false;
-      }
-    }
-    if (instruction is HLocalValue) {
-      needsAssignment = false;
-    }
-
-    if (needsAssignment &&
-        !instruction.isControlFlow() && variableNames.hasName(instruction)) {
-      visitExpression(instruction);
-      assignVariable(variableNames.getName(instruction), pop());
-      return;
-    }
-
-    if (isGeneratingExpression) {
-      visitExpression(instruction);
-    } else {
-      visitStatement(instruction);
-    }
-  }
-
-  void use(HInstruction argument) {
-    if (isGenerateAtUseSite(argument)) {
-      visitExpression(argument);
-    } else if (argument is HCheck && !variableNames.hasName(argument)) {
-      HCheck check = argument;
-      // This can only happen if the checked node does not have a name.
-      assert(!variableNames.hasName(check.checkedInput));
-      use(check.checkedInput);
-    } else {
-      assert(variableNames.hasName(argument));
-      push(new js.VariableUse(variableNames.getName(argument)));
-    }
-  }
-
-  visit(HInstruction node) {
-    node.accept(this);
-  }
-
-  visitExpression(HInstruction node) {
-    bool oldIsGeneratingExpression = isGeneratingExpression;
-    isGeneratingExpression = true;
-    visit(node);
-    isGeneratingExpression = oldIsGeneratingExpression;
-  }
-
-  visitStatement(HInstruction node) {
-    assert(!isGeneratingExpression);
-    visit(node);
-    if (!expressionStack.isEmpty) {
-      assert(expressionStack.length == 1);
-      pushExpressionAsStatement(pop());
-    }
-  }
-
-  void continueAsBreak(LabelDefinition target) {
-    pushStatement(new js.Break(backend.namer.continueLabelName(target)));
-  }
-
-  void implicitContinueAsBreak(JumpTarget target) {
-    pushStatement(new js.Break(
-        backend.namer.implicitContinueLabelName(target)));
-  }
-
-  void implicitBreakWithLabel(JumpTarget target) {
-    pushStatement(new js.Break(backend.namer.implicitBreakLabelName(target)));
-  }
-
-  js.Statement wrapIntoLabels(js.Statement result, List<LabelDefinition> labels) {
-    for (LabelDefinition label in labels) {
-      if (label.isTarget) {
-        String breakLabelString = backend.namer.breakLabelName(label);
-        result = new js.LabeledStatement(breakLabelString, result);
-      }
-    }
-    return result;
-  }
-
-
-  // The regular [visitIf] method implements the needed logic.
-  bool visitIfInfo(HIfBlockInformation info) => false;
-
-  bool visitSwitchInfo(HSwitchBlockInformation info) {
-    bool isExpression = isJSExpression(info.expression);
-    if (!isExpression) {
-      generateStatements(info.expression);
-    }
-
-    if (isExpression) {
-      push(generateExpression(info.expression));
-    } else {
-      use(info.expression.conditionExpression);
-    }
-    js.Expression key = pop();
-    List<js.SwitchClause> cases = <js.SwitchClause>[];
-    HSwitch switchInstruction = info.expression.end.last;
-    List<HInstruction> inputs = switchInstruction.inputs;
-    List<HBasicBlock> successors = switchInstruction.block.successors;
-
-    js.Block oldContainer = currentContainer;
-    for (int inputIndex = 1, statementIndex = 0;
-         inputIndex < inputs.length;
-         statementIndex++) {
-      HBasicBlock successor = successors[inputIndex - 1];
-      // If liveness analysis has figured out that this case is dead,
-      // omit the code for it.
-      if (successor.isLive) {
-        do {
-          visit(inputs[inputIndex]);
-          currentContainer = new js.Block.empty();
-          cases.add(new js.Case(pop(), currentContainer));
-          inputIndex++;
-        } while ((successors[inputIndex - 1] == successor)
-                 && (inputIndex < inputs.length));
-
-        generateStatements(info.statements[statementIndex]);
-      } else {
-        // Skip all the case statements that belong to this
-        // block.
-        while ((successors[inputIndex - 1] == successor)
-              && (inputIndex < inputs.length)) {
-          ++inputIndex;
-        }
-      }
-    }
-
-    // If the default case is dead, we omit it. Likewise, if it is an
-    // empty block, we omit it, too.
-    if (info.statements.last.start.isLive) {
-      currentContainer = new js.Block.empty();
-      generateStatements(info.statements.last);
-      if (currentContainer.statements.isNotEmpty) {
-        cases.add(new js.Default(currentContainer));
-      }
-    }
-
-    currentContainer = oldContainer;
-
-    js.Statement result = new js.Switch(key, cases);
-    pushStatement(wrapIntoLabels(result, info.labels));
-    return true;
-  }
-
-  bool visitSequenceInfo(HStatementSequenceInformation info) {
-    return false;
-  }
-
-  bool visitSubGraphInfo(HSubGraphBlockInformation info) {
-    visitSubGraph(info.subGraph);
-    return true;
-  }
-
-  bool visitSubExpressionInfo(HSubExpressionBlockInformation info) {
-    return false;
-  }
-
-  bool visitAndOrInfo(HAndOrBlockInformation info) {
-    return false;
-  }
-
-  bool visitTryInfo(HTryBlockInformation info) {
-    js.Block body = generateStatementsInNewBlock(info.body);
-    js.Catch catchPart = null;
-    js.Block finallyPart = null;
-    if (info.catchBlock != null) {
-      void register(ClassElement classElement) {
-        if (classElement != null) {
-          registry.registerInstantiatedClass(classElement);
-        }
-      }
-      register(backend.jsPlainJavaScriptObjectClass);
-      register(backend.jsUnknownJavaScriptObjectClass);
-
-      HLocalValue exception = info.catchVariable;
-      String name = variableNames.getName(exception);
-      js.VariableDeclaration decl = new js.VariableDeclaration(name);
-      js.Block catchBlock = generateStatementsInNewBlock(info.catchBlock);
-      catchPart = new js.Catch(decl, catchBlock);
-    }
-    if (info.finallyBlock != null) {
-      finallyPart = generateStatementsInNewBlock(info.finallyBlock);
-    }
-    pushStatement(new js.Try(body, catchPart, finallyPart));
-    return true;
-  }
-
-  void visitBodyIgnoreLabels(HLoopBlockInformation info) {
-    if (info.body.start.isLabeledBlock()) {
-      HBlockInformation oldInfo = currentBlockInformation;
-      currentBlockInformation = info.body.start.blockFlow.body;
-      generateStatements(info.body);
-      currentBlockInformation = oldInfo;
-    } else {
-      generateStatements(info.body);
-    }
-  }
-
-  bool visitLoopInfo(HLoopBlockInformation info) {
-    HExpressionInformation condition = info.condition;
-    bool isConditionExpression = isJSCondition(condition);
-
-    js.Loop loop;
-
-    switch (info.kind) {
-      // Treate all three "test-first" loops the same way.
-      case HLoopBlockInformation.FOR_LOOP:
-      case HLoopBlockInformation.WHILE_LOOP:
-      case HLoopBlockInformation.FOR_IN_LOOP:
-      case HLoopBlockInformation.SWITCH_CONTINUE_LOOP:
-        HBlockInformation initialization = info.initializer;
-        int initializationType = TYPE_STATEMENT;
-        if (initialization != null) {
-          initializationType = expressionType(initialization);
-          if (initializationType == TYPE_STATEMENT) {
-            generateStatements(initialization);
-            initialization = null;
-          }
-        }
-
-        // We inserted a basic block to avoid critical edges. This block is
-        // part of the LoopBlockInformation and must therefore be handled here.
-        js.Block oldContainer = currentContainer;
-        js.Block avoidContainer = new js.Block.empty();
-        currentContainer = avoidContainer;
-        assignPhisOfSuccessors(condition.end.successors.last);
-        bool hasPhiUpdates = !avoidContainer.statements.isEmpty;
-        currentContainer = oldContainer;
-
-        if (isConditionExpression &&
-            !hasPhiUpdates &&
-            info.updates != null && isJSExpression(info.updates)) {
-          // If we have an updates graph, and it's expressible as an
-          // expression, generate a for-loop.
-          js.Expression jsInitialization = null;
-          if (initialization != null) {
-            int delayedVariablesCount = collectedVariableDeclarations.length;
-            jsInitialization = generateExpression(initialization);
-            if (!shouldGroupVarDeclarations &&
-                delayedVariablesCount < collectedVariableDeclarations.length) {
-              // We just added a new delayed variable-declaration. See if we can
-              // put in a 'var' in front of the initialization to make it go
-              // away. We walk the 'tree' of comma-operators to find the
-              // expressions and see if they are all assignments that can be
-              // converted into declarations.
-
-              List<js.Assignment> assignments;
-
-              bool allSimpleAssignments(js.Expression expression) {
-                if (expression is js.Assignment) {
-                  js.Assignment assignment = expression;
-                  if (assignment.leftHandSide is js.VariableUse &&
-                      !assignment.isCompound) {
-                    if (assignments == null) assignments = <js.Assignment>[];
-                    assignments.add(expression);
-                    return true;
-                  }
-                } else if (expression.isCommaOperator) {
-                  js.Binary binary = expression;
-                  return allSimpleAssignments(binary.left)
-                      && allSimpleAssignments(binary.right);
-                }
-                return false;
-              }
-
-              if (allSimpleAssignments(jsInitialization)) {
-                List<js.VariableInitialization> inits =
-                    <js.VariableInitialization>[];
-                for (js.Assignment assignment in assignments) {
-                  String id = (assignment.leftHandSide as js.VariableUse).name;
-                  js.Node declaration = new js.VariableDeclaration(id);
-                  inits.add(new js.VariableInitialization(declaration,
-                                                          assignment.value));
-                  collectedVariableDeclarations.remove(id);
-                  declaredLocals.add(id);
-                }
-                jsInitialization = new js.VariableDeclarationList(inits);
-              }
-            }
-          }
-          js.Expression jsCondition = generateExpression(condition);
-          js.Expression jsUpdates = generateExpression(info.updates);
-          // The body might be labeled. Ignore this when recursing on the
-          // subgraph.
-          // TODO(lrn): Remove this extra labeling when handling all loops
-          // using subgraphs.
-          oldContainer = currentContainer;
-          js.Statement body = new js.Block.empty();
-          currentContainer = body;
-          visitBodyIgnoreLabels(info);
-          currentContainer = oldContainer;
-          body = unwrapStatement(body);
-          loop = new js.For(jsInitialization, jsCondition, jsUpdates, body);
-        } else {
-          // We have either no update graph, or it's too complex to
-          // put in an expression.
-          if (initialization != null) {
-            generateStatements(initialization);
-          }
-          js.Expression jsCondition;
-          js.Block oldContainer = currentContainer;
-          js.Statement body = new js.Block.empty();
-          if (isConditionExpression && !hasPhiUpdates) {
-            jsCondition = generateExpression(condition);
-            currentContainer = body;
-          } else {
-            jsCondition = newLiteralBool(true);
-            currentContainer = body;
-            generateStatements(condition);
-            use(condition.conditionExpression);
-            js.Expression ifTest = new js.Prefix("!", pop());
-            js.Statement jsBreak = new js.Break(null);
-            js.Statement exitLoop;
-            if (avoidContainer.statements.isEmpty) {
-              exitLoop = jsBreak;
-            } else {
-              avoidContainer.statements.add(jsBreak);
-              exitLoop = avoidContainer;
-            }
-            pushStatement(new js.If.noElse(ifTest, exitLoop));
-          }
-          if (info.updates != null) {
-            wrapLoopBodyForContinue(info);
-            generateStatements(info.updates);
-          } else {
-            visitBodyIgnoreLabels(info);
-          }
-          currentContainer = oldContainer;
-          body = unwrapStatement(body);
-          loop = new js.While(jsCondition, body);
-        }
-        break;
-      case HLoopBlockInformation.DO_WHILE_LOOP:
-        if (info.initializer != null) {
-          generateStatements(info.initializer);
-        }
-        // We inserted a basic block to avoid critical edges. This block is
-        // part of the LoopBlockInformation and must therefore be handled here.
-        js.Block oldContainer = currentContainer;
-        js.Block exitAvoidContainer = new js.Block.empty();
-        currentContainer = exitAvoidContainer;
-        assignPhisOfSuccessors(condition.end.successors.last);
-        bool hasExitPhiUpdates = !exitAvoidContainer.statements.isEmpty;
-        currentContainer = oldContainer;
-
-
-        oldContainer = currentContainer;
-        js.Block body = new js.Block.empty();
-        // If there are phi copies in the block that jumps to the
-        // loop entry, we must emit the condition like this:
-        // do {
-        //   body;
-        //   if (condition) {
-        //     phi updates;
-        //     continue;
-        //   } else {
-        //     break;
-        //   }
-        // } while (true);
-        HBasicBlock avoidEdge = info.end.successors[0];
-        js.Block updateBody = new js.Block.empty();
-        currentContainer = updateBody;
-        assignPhisOfSuccessors(avoidEdge);
-        bool hasPhiUpdates = !updateBody.statements.isEmpty;
-        currentContainer = body;
-        visitBodyIgnoreLabels(info);
-        if (info.updates != null) {
-          generateStatements(info.updates);
-        }
-        if (isConditionExpression) {
-          push(generateExpression(condition));
-        } else {
-          generateStatements(condition);
-          use(condition.conditionExpression);
-        }
-        js.Expression jsCondition = pop();
-        if (jsCondition == null) {
-          // If the condition is dead code, we turn the do-while into
-          // a simpler while because we will never reach the condition
-          // at the end of the loop anyway.
-          loop = new js.While(newLiteralBool(true), unwrapStatement(body));
-        } else {
-          if (hasPhiUpdates || hasExitPhiUpdates) {
-            updateBody.statements.add(new js.Continue(null));
-            js.Statement jsBreak = new js.Break(null);
-            js.Statement exitLoop;
-            if (exitAvoidContainer.statements.isEmpty) {
-              exitLoop = jsBreak;
-            } else {
-              exitAvoidContainer.statements.add(jsBreak);
-              exitLoop = exitAvoidContainer;
-            }
-            body.statements.add(
-                new js.If(jsCondition, updateBody, exitLoop));
-            jsCondition = newLiteralBool(true);
-          }
-          loop = new js.Do(unwrapStatement(body), jsCondition);
-        }
-        currentContainer = oldContainer;
-        break;
-      default:
-        compiler.internalError(condition.conditionExpression,
-            'Unexpected loop kind: ${info.kind}.');
-    }
-    js.Statement result =
-        attachLocationRange(loop, info.sourcePosition, info.endSourcePosition);
-    if (info.kind == HLoopBlockInformation.SWITCH_CONTINUE_LOOP) {
-      String continueLabelString =
-          backend.namer.implicitContinueLabelName(info.target);
-      result = new js.LabeledStatement(continueLabelString, result);
-    }
-    pushStatement(wrapIntoLabels(result, info.labels));
-    return true;
-  }
-
-  bool visitLabeledBlockInfo(HLabeledBlockInformation labeledBlockInfo) {
-    Link<Entity> continueOverrides = const Link<Entity>();
-
-    js.Block oldContainer = currentContainer;
-    js.Block body = new js.Block.empty();
-    js.Statement result = body;
-
-    currentContainer = body;
-
-    // If [labeledBlockInfo.isContinue], the block is an artificial
-    // block around the body of a loop with an update block, so that
-    // continues of the loop can be written as breaks of the body
-    // block.
-    if (labeledBlockInfo.isContinue) {
-      for (LabelDefinition label in labeledBlockInfo.labels) {
-        if (label.isContinueTarget) {
-          String labelName = backend.namer.continueLabelName(label);
-          result = new js.LabeledStatement(labelName, result);
-          continueAction[label] = continueAsBreak;
-          continueOverrides = continueOverrides.prepend(label);
-        }
-      }
-      // For handling unlabeled continues from the body of a loop.
-      // TODO(lrn): Consider recording whether the target is in fact
-      // a target of an unlabeled continue, and not generate this if it isn't.
-      JumpTarget target = labeledBlockInfo.target;
-      String labelName = backend.namer.implicitContinueLabelName(target);
-      result = new js.LabeledStatement(labelName, result);
-      continueAction[target] = implicitContinueAsBreak;
-      continueOverrides = continueOverrides.prepend(target);
-    } else {
-      for (LabelDefinition label in labeledBlockInfo.labels) {
-        if (label.isBreakTarget) {
-          String labelName = backend.namer.breakLabelName(label);
-          result = new js.LabeledStatement(labelName, result);
-        }
-      }
-    }
-    JumpTarget target = labeledBlockInfo.target;
-    if (target.isSwitch) {
-      // This is an extra block around a switch that is generated
-      // as a nested if/else chain. We add an extra break target
-      // so that case code can break.
-      String labelName = backend.namer.implicitBreakLabelName(target);
-      result = new js.LabeledStatement(labelName, result);
-      breakAction[target] = implicitBreakWithLabel;
-    }
-
-    currentContainer = body;
-    generateStatements(labeledBlockInfo.body);
-
-    if (labeledBlockInfo.isContinue) {
-      while (!continueOverrides.isEmpty) {
-        continueAction.remove(continueOverrides.head);
-        continueOverrides = continueOverrides.tail;
-      }
-    } else {
-      breakAction.remove(labeledBlockInfo.target);
-    }
-
-    currentContainer = oldContainer;
-    pushStatement(result);
-    return true;
-  }
-
-  // Wraps a loop body in a block to make continues have a target to break
-  // to (if necessary).
-  void wrapLoopBodyForContinue(HLoopBlockInformation info) {
-    JumpTarget target = info.target;
-    if (target != null && target.isContinueTarget) {
-      js.Block oldContainer = currentContainer;
-      js.Block body = new js.Block.empty();
-      currentContainer = body;
-      js.Statement result = body;
-      for (LabelDefinition label in info.labels) {
-        if (label.isContinueTarget) {
-          String labelName = backend.namer.continueLabelName(label);
-          result = new js.LabeledStatement(labelName, result);
-          continueAction[label] = continueAsBreak;
-        }
-      }
-      String labelName = backend.namer.implicitContinueLabelName(target);
-      result = new js.LabeledStatement(labelName, result);
-      continueAction[info.target] = implicitContinueAsBreak;
-      visitBodyIgnoreLabels(info);
-      continueAction.remove(info.target);
-      for (LabelDefinition label in info.labels) {
-        if (label.isContinueTarget) {
-          continueAction.remove(label);
-        }
-      }
-      currentContainer = oldContainer;
-      pushStatement(result);
-    } else {
-      // Loop body contains no continues, so we don't need a break target.
-      generateStatements(info.body);
-    }
-  }
-
-  bool handleBlockFlow(HBlockFlow block) {
-    HBlockInformation info = block.body;
-    // If we reach here again while handling the attached information,
-    // e.g., because we call visitSubGraph on a subgraph starting on
-    // the same block, don't handle it again.
-    // When the structure graph is complete, we will be able to have
-    // different structures starting on the same basic block (e.g., an
-    // "if" and its condition).
-    if (identical(info, currentBlockInformation)) return false;
-
-    HBlockInformation oldBlockInformation = currentBlockInformation;
-    currentBlockInformation = info;
-    bool success = info.accept(this);
-    currentBlockInformation = oldBlockInformation;
-    if (success) {
-      HBasicBlock continuation = block.continuation;
-      if (continuation != null) {
-        visitBasicBlock(continuation);
-      }
-    }
-    return success;
-  }
-
-  void visitBasicBlock(HBasicBlock node) {
-    if (!node.isLive) return;
-
-    // Abort traversal if we are leaving the currently active sub-graph.
-    if (!subGraph.contains(node)) return;
-
-    // If this node has block-structure based information attached,
-    // try using that to traverse from here.
-    if (node.blockFlow != null && handleBlockFlow(node.blockFlow)) {
-      return;
-    }
-    iterateBasicBlock(node);
-  }
-
-  void emitAssignment(String destination, String source) {
-    assignVariable(destination, new js.VariableUse(source));
-  }
-
-  /**
-   * Sequentialize a list of conceptually parallel copies. Parallel
-   * copies may contain cycles, that this method breaks.
-   */
-  void sequentializeCopies(Iterable<Copy> copies,
-                           String tempName,
-                           void doAssignment(String target, String source)) {
-    // Map to keep track of the current location (ie the variable that
-    // holds the initial value) of a variable.
-    Map<String, String> currentLocation = new Map<String, String>();
-
-    // Map to keep track of the initial value of a variable.
-    Map<String, String> initialValue = new Map<String, String>();
-
-    // List of variables to assign a value.
-    List<String> worklist = <String>[];
-
-    // List of variables that we can assign a value to (ie are not
-    // being used anymore).
-    List<String> ready = <String>[];
-
-    // Prune [copies] by removing self-copies.
-    List<Copy> prunedCopies = <Copy>[];
-    for (Copy copy in copies) {
-      if (copy.source != copy.destination) {
-        prunedCopies.add(copy);
-      }
-    }
-    copies = prunedCopies;
-
-
-    // For each copy, set the current location of the source to
-    // itself, and the initial value of the destination to the source.
-    // Add the destination to the list of copies to make.
-    for (Copy copy in copies) {
-      currentLocation[copy.source] = copy.source;
-      initialValue[copy.destination] = copy.source;
-      worklist.add(copy.destination);
-    }
-
-    // For each copy, if the destination does not have a current
-    // location, then we can safely assign to it.
-    for (Copy copy in copies) {
-      if (currentLocation[copy.destination] == null) {
-        ready.add(copy.destination);
-      }
-    }
-
-    while (!worklist.isEmpty) {
-      while (!ready.isEmpty) {
-        String destination = ready.removeLast();
-        String source = initialValue[destination];
-        // Since [source] might have been updated, use the current
-        // location of [source]
-        String copy = currentLocation[source];
-        doAssignment(destination, copy);
-        // Now [destination] is the current location of [source].
-        currentLocation[source] = destination;
-        // If [source] hasn't been updated and needs to have a value,
-        // add it to the list of variables that can be updated. Copies
-        // of [source] will now use [destination].
-        if (source == copy && initialValue[source] != null) {
-          ready.add(source);
-        }
-      }
-
-      // Check if we have a cycle.
-      String current = worklist.removeLast();
-      // If [current] is used as a source, and the assignment has been
-      // done, we are done with this variable. Otherwise there is a
-      // cycle that we break by using a temporary name.
-      if (currentLocation[current] != null
-          && current != currentLocation[initialValue[current]]) {
-        doAssignment(tempName, current);
-        currentLocation[current] = tempName;
-        // [current] can now be safely updated. Copies of [current]
-        // will now use [tempName].
-        ready.add(current);
-      }
-    }
-  }
-
-  void assignPhisOfSuccessors(HBasicBlock node) {
-    CopyHandler handler = variableNames.getCopyHandler(node);
-    if (handler == null) return;
-
-    // Map the instructions to strings.
-    Iterable<Copy> copies = handler.copies.map((Copy copy) {
-      return new Copy(variableNames.getName(copy.source),
-                      variableNames.getName(copy.destination));
-    });
-
-    sequentializeCopies(copies, variableNames.getSwapTemp(), emitAssignment);
-
-    for (Copy copy in handler.assignments) {
-      String name = variableNames.getName(copy.destination);
-      use(copy.source);
-      assignVariable(name, pop());
-    }
-  }
-
-  void iterateBasicBlock(HBasicBlock node) {
-    HInstruction instruction = node.first;
-    while (!identical(instruction, node.last)) {
-      if (!isGenerateAtUseSite(instruction)) {
-        define(instruction);
-      }
-      instruction = instruction.next;
-    }
-    assignPhisOfSuccessors(node);
-    visit(instruction);
-  }
-
-  visitInvokeBinary(HInvokeBinary node, String op) {
-    use(node.left);
-    js.Expression jsLeft = pop();
-    use(node.right);
-    push(new js.Binary(op, jsLeft, pop()), node);
-  }
-
-  visitRelational(HRelational node, String op) => visitInvokeBinary(node, op);
-
-  // We want the outcome of bit-operations to be positive. We use the unsigned
-  // shift operator to achieve this.
-  visitBitInvokeBinary(HBinaryBitOp node, String op) {
-    visitInvokeBinary(node, op);
-    if (op != '>>>' && requiresUintConversion(node)) {
-      push(new js.Binary(">>>", pop(), new js.LiteralNumber("0")), node);
-    }
-  }
-
-  visitInvokeUnary(HInvokeUnary node, String op) {
-    use(node.operand);
-    push(new js.Prefix(op, pop()), node);
-  }
-
-  // We want the outcome of bit-operations to be positive. We use the unsigned
-  // shift operator to achieve this.
-  visitBitInvokeUnary(HInvokeUnary node, String op) {
-    visitInvokeUnary(node, op);
-    if (requiresUintConversion(node)) {
-      push(new js.Binary(">>>", pop(), new js.LiteralNumber("0")), node);
-    }
-  }
-
-  void emitIdentityComparison(HIdentity instruction, bool inverse) {
-    String op = instruction.singleComparisonOp;
-    HInstruction left = instruction.left;
-    HInstruction right = instruction.right;
-    if (op != null) {
-      use(left);
-      js.Expression jsLeft = pop();
-      use(right);
-      push(new js.Binary(mapRelationalOperator(op, inverse), jsLeft, pop()));
-    } else {
-      assert(NullConstantValue.JsNull == 'null');
-      use(left);
-      js.Binary leftEqualsNull =
-          new js.Binary("==", pop(), new js.LiteralNull());
-      use(right);
-      js.Binary rightEqualsNull =
-          new js.Binary(mapRelationalOperator("==", inverse),
-                        pop(), new js.LiteralNull());
-      use(right);
-      use(left);
-      js.Binary tripleEq = new js.Binary(mapRelationalOperator("===", inverse),
-                                         pop(), pop());
-
-      push(new js.Conditional(leftEqualsNull, rightEqualsNull, tripleEq));
-    }
-  }
-
-  visitIdentity(HIdentity node) {
-    emitIdentityComparison(node, false);
-  }
-
-  visitAdd(HAdd node)               => visitInvokeBinary(node, '+');
-  visitDivide(HDivide node)         => visitInvokeBinary(node, '/');
-  visitMultiply(HMultiply node)     => visitInvokeBinary(node, '*');
-  visitSubtract(HSubtract node)     => visitInvokeBinary(node, '-');
-  visitBitAnd(HBitAnd node)         => visitBitInvokeBinary(node, '&');
-  visitBitNot(HBitNot node)         => visitBitInvokeUnary(node, '~');
-  visitBitOr(HBitOr node)           => visitBitInvokeBinary(node, '|');
-  visitBitXor(HBitXor node)         => visitBitInvokeBinary(node, '^');
-  visitShiftLeft(HShiftLeft node)   => visitBitInvokeBinary(node, '<<');
-  visitShiftRight(HShiftRight node) => visitBitInvokeBinary(node, '>>>');
-
-  visitTruncatingDivide(HTruncatingDivide node) {
-    assert(node.left.isUInt31(compiler));
-    assert(node.right.isPositiveInteger(compiler));
-    use(node.left);
-    js.Expression jsLeft = pop();
-    use(node.right);
-    push(new js.Binary('/', jsLeft, pop()), node);
-    push(new js.Binary('|', pop(), new js.LiteralNumber("0")), node);
-  }
-
-  visitNegate(HNegate node)         => visitInvokeUnary(node, '-');
-
-  visitLess(HLess node)                 => visitRelational(node, '<');
-  visitLessEqual(HLessEqual node)       => visitRelational(node, '<=');
-  visitGreater(HGreater node)           => visitRelational(node, '>');
-  visitGreaterEqual(HGreaterEqual node) => visitRelational(node, '>=');
-
-  visitBoolify(HBoolify node) {
-    assert(node.inputs.length == 1);
-    use(node.inputs[0]);
-    push(new js.Binary('===', pop(), newLiteralBool(true)), node);
-  }
-
-  visitExit(HExit node) {
-    // Don't do anything.
-  }
-
-  visitGoto(HGoto node) {
-    HBasicBlock block = node.block;
-    assert(block.successors.length == 1);
-    List<HBasicBlock> dominated = block.dominatedBlocks;
-    // With the exception of the entry-node which dominates its successor
-    // and the exit node, no block finishing with a 'goto' can have more than
-    // one dominated block (since it has only one successor).
-    // If the successor is dominated by another block, then the other block
-    // is responsible for visiting the successor.
-    if (dominated.isEmpty) return;
-    if (dominated.length > 2) {
-      compiler.internalError(node, 'dominated.length = ${dominated.length}');
-    }
-    if (dominated.length == 2 && block != currentGraph.entry) {
-      compiler.internalError(node, 'node.block != currentGraph.entry');
-    }
-    assert(dominated[0] == block.successors[0]);
-    visitBasicBlock(dominated[0]);
-  }
-
-  visitLoopBranch(HLoopBranch node) {
-    assert(node.block == subGraph.end);
-    // We are generating code for a loop condition.
-    // If we are generating the subgraph as an expression, the
-    // condition will be generated as the expression.
-    // Otherwise, we don't generate the expression, and leave that
-    // to the code that called [visitSubGraph].
-    if (isGeneratingExpression) {
-      use(node.inputs[0]);
-    }
-  }
-
-  /**
-   * Checks if [map] contains an [EntityAction] for [entity], and
-   * if so calls that action and returns true.
-   * Otherwise returns false.
-   */
-  bool tryCallAction(Map<Entity, EntityAction> map, Entity entity) {
-    EntityAction action = map[entity];
-    if (action == null) return false;
-    action(entity);
-    return true;
-  }
-
-  visitBreak(HBreak node) {
-    assert(node.block.successors.length == 1);
-    if (node.label != null) {
-      LabelDefinition label = node.label;
-      if (!tryCallAction(breakAction, label)) {
-        pushStatement(new js.Break(backend.namer.breakLabelName(label)), node);
-      }
-    } else {
-      JumpTarget target = node.target;
-      if (!tryCallAction(breakAction, target)) {
-        if (node.breakSwitchContinueLoop) {
-          pushStatement(new js.Break(
-              backend.namer.implicitContinueLabelName(target)), node);
-        } else {
-          pushStatement(new js.Break(null), node);
-        }
-      }
-    }
-  }
-
-  visitContinue(HContinue node) {
-    assert(node.block.successors.length == 1);
-    if (node.label != null) {
-      LabelDefinition label = node.label;
-      if (!tryCallAction(continueAction, label)) {
-        // TODO(floitsch): should this really be the breakLabelName?
-        pushStatement(new js.Continue(backend.namer.breakLabelName(label)),
-                      node);
-      }
-    } else {
-      JumpTarget target = node.target;
-      if (!tryCallAction(continueAction, target)) {
-        if (target.statement is ast.SwitchStatement) {
-          pushStatement(new js.Continue(
-              backend.namer.implicitContinueLabelName(target)), node);
-        } else {
-          pushStatement(new js.Continue(null), node);
-        }
-      }
-    }
-  }
-
-  visitExitTry(HExitTry node) {
-    // An [HExitTry] is used to represent the control flow graph of a
-    // try/catch block, ie the try body is always a predecessor
-    // of the catch and finally. Here, we continue visiting the try
-    // body by visiting the block that contains the user-level control
-    // flow instruction.
-    visitBasicBlock(node.bodyTrySuccessor);
-  }
-
-  visitTry(HTry node) {
-    // We should never get here. Try/catch/finally is always handled using block
-    // information in [visitTryInfo].
-    compiler.internalError(node, 'visitTry should not be called.');
-  }
-
-  bool tryControlFlowOperation(HIf node) {
-    if (!controlFlowOperators.contains(node)) return false;
-    HPhi phi = node.joinBlock.phis.first;
-    bool atUseSite = isGenerateAtUseSite(phi);
-    // Don't generate a conditional operator in this situation:
-    // i = condition ? bar() : i;
-    // But generate this instead:
-    // if (condition) i = bar();
-    // Usually, the variable name is longer than 'if' and it takes up
-    // more space to duplicate the name.
-    if (!atUseSite
-        && variableNames.getName(phi) == variableNames.getName(phi.inputs[1])) {
-      return false;
-    }
-    if (!atUseSite) define(phi);
-    visitBasicBlock(node.joinBlock);
-    return true;
-  }
-
-  void generateIf(HIf node, HIfBlockInformation info) {
-    use(node.inputs[0]);
-    js.Expression test = pop();
-
-    HStatementInformation thenGraph = info.thenGraph;
-    HStatementInformation elseGraph = info.elseGraph;
-    js.Statement thenPart =
-        unwrapStatement(generateStatementsInNewBlock(thenGraph));
-    js.Statement elsePart =
-        unwrapStatement(generateStatementsInNewBlock(elseGraph));
-
-    pushStatement(new js.If(test, thenPart, elsePart), node);
-  }
-
-  visitIf(HIf node) {
-    if (tryControlFlowOperation(node)) return;
-
-    HInstruction condition = node.inputs[0];
-    HIfBlockInformation info = node.blockInformation.body;
-
-    if (condition.isConstant()) {
-      HConstant constant = condition;
-      if (constant.constant.isTrue) {
-        generateStatements(info.thenGraph);
-      } else {
-        generateStatements(info.elseGraph);
-      }
-    } else {
-      generateIf(node, info);
-    }
-
-    HBasicBlock joinBlock = node.joinBlock;
-    if (joinBlock != null && !identical(joinBlock.dominator, node.block)) {
-      // The join block is dominated by a block in one of the branches.
-      // The subgraph traversal never reached it, so we visit it here
-      // instead.
-      visitBasicBlock(joinBlock);
-    }
-
-    // Visit all the dominated blocks that are not part of the then or else
-    // branches, and is not the join block.
-    // Depending on how the then/else branches terminate
-    // (e.g., return/throw/break) there can be any number of these.
-    List<HBasicBlock> dominated = node.block.dominatedBlocks;
-    for (int i = 2; i < dominated.length; i++) {
-      visitBasicBlock(dominated[i]);
-    }
-  }
-
-  js.Call jsPropertyCall(js.Expression receiver,
-                         String fieldName,
-                         List<js.Expression> arguments) {
-    return new js.Call(new js.PropertyAccess.field(receiver, fieldName),
-                       arguments);
-  }
-
-  void visitInterceptor(HInterceptor node) {
-    registry.registerSpecializedGetInterceptor(node.interceptedClasses);
-    String name = backend.namer.getInterceptorName(
-        backend.getInterceptorMethod, node.interceptedClasses);
-    var isolate = new js.VariableUse(
-        backend.namer.globalObjectFor(backend.interceptorsLibrary));
-    use(node.receiver);
-    List<js.Expression> arguments = <js.Expression>[pop()];
-    push(jsPropertyCall(isolate, name, arguments), node);
-    registry.registerUseInterceptor();
-  }
-
-  visitInvokeDynamicMethod(HInvokeDynamicMethod node) {
-    use(node.receiver);
-    js.Expression object = pop();
-    String name = node.selector.name;
-    String methodName;
-    List<js.Expression> arguments = visitArguments(node.inputs);
-    Element target = node.element;
-
-    if (target != null && !node.isInterceptedCall) {
-      if (target == backend.jsArrayAdd) {
-        methodName = 'push';
-      } else if (target == backend.jsArrayRemoveLast) {
-        methodName = 'pop';
-      } else if (target == backend.jsStringSplit) {
-        methodName = 'split';
-        // Split returns a List, so we make sure the backend knows the
-        // list class is instantiated.
-        registry.registerInstantiatedClass(compiler.listClass);
-      } else if (target.isNative && target.isFunction
-                 && !node.isInterceptedCall) {
-        // A direct (i.e. non-interceptor) native call is the result of
-        // optimization.  The optimization ensures any type checks or
-        // conversions have been satisified.
-        methodName = target.fixedBackendName;
-      }
-    }
-
-    if (methodName == null) {
-      methodName = backend.namer.invocationName(node.selector);
-      registerMethodInvoke(node);
-    }
-    push(jsPropertyCall(object, methodName, arguments), node);
-  }
-
-  void visitInvokeConstructorBody(HInvokeConstructorBody node) {
-    use(node.inputs[0]);
-    js.Expression object = pop();
-    String methodName = backend.namer.getNameOfInstanceMember(node.element);
-    List<js.Expression> arguments = visitArguments(node.inputs);
-    push(jsPropertyCall(object, methodName, arguments), node);
-    registry.registerStaticUse(node.element);
-  }
-
-  void visitOneShotInterceptor(HOneShotInterceptor node) {
-    List<js.Expression> arguments = visitArguments(node.inputs);
-    var isolate = new js.VariableUse(
-        backend.namer.globalObjectFor(backend.interceptorsLibrary));
-    Selector selector = getOptimizedSelectorFor(node, node.selector);
-    String methodName = backend.registerOneShotInterceptor(selector);
-    push(jsPropertyCall(isolate, methodName, arguments), node);
-    if (selector.isGetter) {
-      registerGetter(node);
-    } else if (selector.isSetter) {
-      registerSetter(node);
-    } else {
-      registerMethodInvoke(node);
-    }
-    registry.registerUseInterceptor();
-  }
-
-  Selector getOptimizedSelectorFor(HInvokeDynamic node, Selector selector) {
-    if (node.element != null) {
-      // Create an artificial type mask to make sure only
-      // [node.element] will be enqueued. We're not using the receiver
-      // type because our optimizations might end up in a state where the
-      // invoke dynamic knows more than the receiver.
-      ClassElement enclosing = node.element.enclosingClass;
-      TypeMask receiverType =
-          new TypeMask.nonNullExact(enclosing.declaration, compiler.world);
-      return new TypedSelector(receiverType, selector, compiler.world);
-    }
-    // If [JSInvocationMirror._invokeOn] is enabled, and this call
-    // might hit a `noSuchMethod`, we register an untyped selector.
-    return selector.extendIfReachesAll(compiler);
-  }
-
-  void registerMethodInvoke(HInvokeDynamic node) {
-    Selector selector = getOptimizedSelectorFor(node, node.selector);
-
-    // If we don't know what we're calling or if we are calling a getter,
-    // we need to register that fact that we may be calling a closure
-    // with the same arguments.
-    Element target = node.element;
-    if (target == null || target.isGetter) {
-      // TODO(kasperl): If we have a typed selector for the call, we
-      // may know something about the types of closures that need
-      // the specific closure call method.
-      Selector call = new Selector.callClosureFrom(selector);
-      registry.registerDynamicInvocation(call);
-    }
-    registry.registerDynamicInvocation(selector);
-  }
-
-  void registerSetter(HInvokeDynamic node) {
-    Selector selector = getOptimizedSelectorFor(node, node.selector);
-    registry.registerDynamicSetter(selector);
-  }
-
-  void registerGetter(HInvokeDynamic node) {
-    Selector selector = getOptimizedSelectorFor(node, node.selector);
-    registry.registerDynamicGetter(selector);
-  }
-
-  visitInvokeDynamicSetter(HInvokeDynamicSetter node) {
-    use(node.receiver);
-    String name = backend.namer.invocationName(node.selector);
-    push(jsPropertyCall(pop(), name, visitArguments(node.inputs)), node);
-    registerSetter(node);
-  }
-
-  visitInvokeDynamicGetter(HInvokeDynamicGetter node) {
-    use(node.receiver);
-    String name = backend.namer.invocationName(node.selector);
-    push(jsPropertyCall(pop(), name, visitArguments(node.inputs)), node);
-    registerGetter(node);
-  }
-
-  visitInvokeClosure(HInvokeClosure node) {
-    Selector call = new Selector.callClosureFrom(node.selector);
-    use(node.receiver);
-    push(jsPropertyCall(pop(),
-                        backend.namer.invocationName(call),
-                        visitArguments(node.inputs)),
-         node);
-    registry.registerDynamicInvocation(call);
-  }
-
-  visitInvokeStatic(HInvokeStatic node) {
-    Element element = node.element;
-    ClassElement cls = element.enclosingClass;
-    List<DartType> instantiatedTypes = node.instantiatedTypes;
-
-    registry.registerStaticUse(element);
-
-    if (instantiatedTypes != null && !instantiatedTypes.isEmpty) {
-      instantiatedTypes.forEach((type) {
-        registry.registerInstantiatedType(type);
-      });
-    }
-
-    push(backend.namer.elementAccess(node.element));
-    push(new js.Call(pop(), visitArguments(node.inputs, start: 0)), node);
-  }
-
-  visitInvokeSuper(HInvokeSuper node) {
-    Element superMethod = node.element;
-    registry.registerStaticUse(superMethod);
-    ClassElement superClass = superMethod.enclosingClass;
-    if (superMethod.kind == ElementKind.FIELD) {
-      String fieldName = backend.namer.instanceFieldPropertyName(superMethod);
-      use(node.inputs[0]);
-      js.PropertyAccess access =
-          new js.PropertyAccess.field(pop(), fieldName);
-      if (node.isSetter) {
-        use(node.value);
-        push(new js.Assignment(access, pop()), node);
-      } else {
-        push(access, node);
-      }
-    } else {
-      Selector selector = node.selector;
-      String methodName;
-      if (selector.isGetter) {
-        // If the selector we need to register a typed getter to the
-        // [world]. The emitter needs to know if it needs to emit a
-        // bound closure for a method.
-        TypeMask receiverType =
-            new TypeMask.nonNullExact(superClass, compiler.world);
-        selector = new TypedSelector(receiverType, selector, compiler.world);
-        // TODO(floitsch): we know the target. We shouldn't register a
-        // dynamic getter.
-        registry.registerDynamicGetter(selector);
-        registry.registerGetterForSuperMethod(node.element);
-        methodName = backend.namer.invocationName(selector);
-      } else {
-        methodName = backend.namer.getNameOfInstanceMember(superMethod);
-      }
-      push(
-          js.js('#.prototype.#.call(#)', [
-              backend.namer.elementAccess(superClass),
-              methodName, visitArguments(node.inputs, start: 0)]),
-          node);
-    }
-  }
-
-  visitFieldGet(HFieldGet node) {
-    use(node.receiver);
-    Element element = node.element;
-    if (node.isNullCheck) {
-      // We access a JavaScript member we know all objects besides
-      // null and undefined have: V8 does not like accessing a member
-      // that does not exist.
-      push(new js.PropertyAccess.field(pop(), 'toString'), node);
-    } else if (element == backend.jsIndexableLength) {
-      // We're accessing a native JavaScript property called 'length'
-      // on a JS String or a JS array. Therefore, the name of that
-      // property should not be mangled.
-      push(new js.PropertyAccess.field(pop(), 'length'), node);
-    } else {
-      String name = backend.namer.instanceFieldPropertyName(element);
-      push(new js.PropertyAccess.field(pop(), name), node);
-      registry.registerFieldGetter(element);
-    }
-  }
-
-  visitFieldSet(HFieldSet node) {
-    Element element = node.element;
-    registry.registerFieldSetter(element);
-    String name = backend.namer.instanceFieldPropertyName(element);
-    use(node.receiver);
-    js.Expression receiver = pop();
-    use(node.value);
-    push(new js.Assignment(new js.PropertyAccess.field(receiver, name), pop()),
-        node);
-  }
-
-  visitReadModifyWrite(HReadModifyWrite node) {
-    Element element = node.element;
-    registry.registerFieldSetter(element);
-    String name = backend.namer.instanceFieldPropertyName(element);
-    use(node.receiver);
-    js.Expression fieldReference = new js.PropertyAccess.field(pop(), name);
-    if (node.isPreOp) {
-      push(new js.Prefix(node.jsOp, fieldReference), node);
-    } else if (node.isPostOp) {
-      push(new js.Postfix(node.jsOp, fieldReference), node);
-    } else {
-      use(node.value);
-      push(new js.Assignment.compound(fieldReference, node.jsOp, pop()), node);
-    }
-  }
-
-  visitLocalGet(HLocalGet node) {
-    use(node.receiver);
-  }
-
-  visitLocalSet(HLocalSet node) {
-    use(node.value);
-    assignVariable(variableNames.getName(node.receiver), pop());
-  }
-
-  void registerForeignTypes(HForeign node) {
-    native.NativeBehavior nativeBehavior = node.nativeBehavior;
-    if (nativeBehavior == null) return;
-    nativeBehavior.typesReturned.forEach((type) {
-      if (type is InterfaceType) {
-        registry.registerInstantiatedType(type);
-      }
-    });
-  }
-
-  visitForeign(HForeign node) {
-    List<HInstruction> inputs = node.inputs;
-    if (node.isJsStatement()) {
-      List<js.Expression> interpolatedExpressions = <js.Expression>[];
-      for (int i = 0; i < inputs.length; i++) {
-        use(inputs[i]);
-        interpolatedExpressions.add(pop());
-      }
-      pushStatement(node.codeTemplate.instantiate(interpolatedExpressions));
-    } else {
-      List<js.Expression> interpolatedExpressions = <js.Expression>[];
-      for (int i = 0; i < inputs.length; i++) {
-        use(inputs[i]);
-        interpolatedExpressions.add(pop());
-      }
-      push(node.codeTemplate.instantiate(interpolatedExpressions));
-    }
-
-    // TODO(sra): Tell world.nativeEnqueuer about the types created here.
-    registerForeignTypes(node);
-  }
-
-  visitForeignNew(HForeignNew node) {
-    js.Expression jsClassReference = backend.namer.elementAccess(node.element);
-    List<js.Expression> arguments = visitArguments(node.inputs, start: 0);
-    push(new js.New(jsClassReference, arguments), node);
-    registerForeignTypes(node);
-    if (node.instantiatedTypes == null) {
-      return;
-    }
-    node.instantiatedTypes.forEach((type) {
-      registry.registerInstantiatedType(type);
-    });
-  }
-
-  js.Expression newLiteralBool(bool value) {
-    if (compiler.enableMinification) {
-      // Use !0 for true, !1 for false.
-      return new js.Prefix("!", new js.LiteralNumber(value ? "0" : "1"));
-    } else {
-      return new js.LiteralBool(value);
-    }
-  }
-
-  void generateConstant(ConstantValue constant) {
-    if (constant.isFunction) {
-      FunctionConstantValue function = constant;
-      registry.registerStaticUse(function.element);
-    }
-    if (constant.isType) {
-      // If the type is a web component, we need to ensure the constructors are
-      // available to 'upgrade' the native object.
-      TypeConstantValue type = constant;
-      Element element = type.representedType.element;
-      if (element != null && element.isClass) {
-        registry.registerTypeConstant(element);
-      }
-    }
-    push(backend.emitter.constantReference(constant));
-  }
-
-  visitConstant(HConstant node) {
-    assert(isGenerateAtUseSite(node));
-    generateConstant(node.constant);
-
-    registry.registerCompileTimeConstant(node.constant);
-    backend.constants.addCompileTimeConstantForEmission(node.constant);
-  }
-
-  visitNot(HNot node) {
-    assert(node.inputs.length == 1);
-    generateNot(node.inputs[0]);
-    attachLocationToLast(node);
-  }
-
-  static String mapRelationalOperator(String op, bool inverse) {
-    Map<String, String> inverseOperator = const <String, String>{
-      "==" : "!=",
-      "!=" : "==",
-      "===": "!==",
-      "!==": "===",
-      "<"  : ">=",
-      "<=" : ">",
-      ">"  : "<=",
-      ">=" : "<"
-    };
-    return inverse ? inverseOperator[op] : op;
-  }
-
-  void generateNot(HInstruction input) {
-    bool canGenerateOptimizedComparison(HInstruction instruction) {
-      if (instruction is !HRelational) return false;
-
-      HRelational relational = instruction;
-      BinaryOperation operation = relational.operation(backend.constantSystem);
-
-      HInstruction left = relational.left;
-      HInstruction right = relational.right;
-      if (left.isStringOrNull(compiler) && right.isStringOrNull(compiler)) {
-        return true;
-      }
-
-      // This optimization doesn't work for NaN, so we only do it if the
-      // type is known to be an integer.
-      return left.isInteger(compiler) && right.isInteger(compiler);
-    }
-
-    bool handledBySpecialCase = false;
-    if (isGenerateAtUseSite(input)) {
-      handledBySpecialCase = true;
-      if (input is HIs) {
-        emitIs(input, '!==');
-      } else if (input is HIsViaInterceptor) {
-        emitIsViaInterceptor(input, true);
-      } else if (input is HNot) {
-        use(input.inputs[0]);
-      } else if (input is HIdentity) {
-        emitIdentityComparison(input, true);
-      } else if (input is HBoolify) {
-        use(input.inputs[0]);
-        push(new js.Binary("!==", pop(), newLiteralBool(true)), input);
-      } else if (canGenerateOptimizedComparison(input)) {
-        HRelational relational = input;
-        BinaryOperation operation =
-            relational.operation(backend.constantSystem);
-        String op = mapRelationalOperator(operation.name, true);
-        visitRelational(input, op);
-      } else {
-        handledBySpecialCase = false;
-      }
-    }
-    if (!handledBySpecialCase) {
-      use(input);
-      push(new js.Prefix("!", pop()));
-    }
-  }
-
-  visitParameterValue(HParameterValue node) {
-    assert(!isGenerateAtUseSite(node));
-    String name = variableNames.getName(node);
-    parameters.add(new js.Parameter(name));
-    declaredLocals.add(name);
-  }
-
-  visitLocalValue(HLocalValue node) {
-    assert(!isGenerateAtUseSite(node));
-    String name = variableNames.getName(node);
-    collectedVariableDeclarations.add(name);
-  }
-
-  visitPhi(HPhi node) {
-    // This method is only called for phis that are generated at use
-    // site. A phi can be generated at use site only if it is the
-    // result of a control flow operation.
-    HBasicBlock ifBlock = node.block.dominator;
-    assert(controlFlowOperators.contains(ifBlock.last));
-    HInstruction input = ifBlock.last.inputs[0];
-    if (input.isConstantFalse()) {
-      use(node.inputs[1]);
-    } else if (input.isConstantTrue()) {
-      use(node.inputs[0]);
-    } else if (node.inputs[1].isConstantBoolean()) {
-      String operation = node.inputs[1].isConstantFalse() ? '&&' : '||';
-      if (operation == '||') {
-        generateNot(input);
-      } else {
-        use(input);
-      }
-      js.Expression left = pop();
-      use(node.inputs[0]);
-      push(new js.Binary(operation, left, pop()));
-    } else {
-      use(input);
-      js.Expression test = pop();
-      use(node.inputs[0]);
-      js.Expression then = pop();
-      use(node.inputs[1]);
-      push(new js.Conditional(test, then, pop()));
-    }
-  }
-
-  visitReturn(HReturn node) {
-    assert(node.inputs.length == 1);
-    HInstruction input = node.inputs[0];
-    if (input.isConstantNull()) {
-      pushStatement(new js.Return(null), node);
-    } else {
-      use(node.inputs[0]);
-      pushStatement(new js.Return(pop()), node);
-    }
-  }
-
-  visitThis(HThis node) {
-    push(new js.This());
-  }
-
-  visitThrow(HThrow node) {
-    if (node.isRethrow) {
-      use(node.inputs[0]);
-      pushStatement(new js.Throw(pop()), node);
-    } else {
-      generateThrowWithHelper('wrapException', node.inputs[0]);
-    }
-  }
-
-  visitRangeConversion(HRangeConversion node) {
-    // Range conversion instructions are removed by the value range
-    // analyzer.
-    assert(false);
-  }
-
-  visitBoundsCheck(HBoundsCheck node) {
-    // TODO(ngeoffray): Separate the two checks of the bounds check, so,
-    // e.g., the zero checks can be shared if possible.
-
-    // If the checks always succeeds, we would have removed the bounds check
-    // completely.
-    assert(node.staticChecks != HBoundsCheck.ALWAYS_TRUE);
-    if (node.staticChecks != HBoundsCheck.ALWAYS_FALSE) {
-      js.Expression under;
-      js.Expression over;
-      if (node.staticChecks != HBoundsCheck.ALWAYS_ABOVE_ZERO) {
-        use(node.index);
-        if (node.index.isInteger(compiler)) {
-          under = js.js("# < 0", pop());
-        } else {
-          js.Expression jsIndex = pop();
-          under = js.js("# >>> 0 !== #", [jsIndex, jsIndex]);
-        }
-      } else if (!node.index.isInteger(compiler)) {
-        checkInt(node.index, '!==');
-        under = pop();
-      }
-      if (node.staticChecks != HBoundsCheck.ALWAYS_BELOW_LENGTH) {
-        var index = node.index;
-        use(index);
-        js.Expression jsIndex = pop();
-        use(node.length);
-        over = new js.Binary(">=", jsIndex, pop());
-      }
-      assert(over != null || under != null);
-      js.Expression underOver = under == null
-          ? over
-          : over == null
-              ? under
-              : new js.Binary("||", under, over);
-      js.Statement thenBody = new js.Block.empty();
-      js.Block oldContainer = currentContainer;
-      currentContainer = thenBody;
-      generateThrowWithHelper('ioore', [node.array, node.index]);
-      currentContainer = oldContainer;
-      thenBody = unwrapStatement(thenBody);
-      pushStatement(new js.If.noElse(underOver, thenBody), node);
-    } else {
-      generateThrowWithHelper('ioore', [node.array, node.index]);
-    }
-  }
-
-  void generateThrowWithHelper(String helperName, argument) {
-    Element helper = backend.findHelper(helperName);
-    registry.registerStaticUse(helper);
-    js.Expression jsHelper = backend.namer.elementAccess(helper);
-    List arguments = [];
-    var location;
-    if (argument is List) {
-      location = argument[0];
-      argument.forEach((instruction) {
-        use(instruction);
-        arguments.add(pop());
-      });
-    } else {
-      location = argument;
-      use(argument);
-      arguments.add(pop());
-    }
-    js.Call value = new js.Call(jsHelper, arguments.toList(growable: false));
-    value = attachLocation(value, location);
-    // BUG(4906): Using throw/return here adds to the size of the generated code
-    // but it has the advantage of explicitly telling the JS engine that
-    // this code path will terminate abruptly. Needs more work.
-    if (helperName == 'wrapException') {
-      pushStatement(new js.Throw(value));
-    } else {
-      pushStatement(new js.Return(value));
-    }
-  }
-
-  visitThrowExpression(HThrowExpression node) {
-    HInstruction argument = node.inputs[0];
-    use(argument);
-
-    Element helper = backend.findHelper("throwExpression");
-    registry.registerStaticUse(helper);
-
-    js.Expression jsHelper = backend.namer.elementAccess(helper);
-    js.Call value = new js.Call(jsHelper, [pop()]);
-    value = attachLocation(value, argument);
-    push(value, node);
-  }
-
-  void visitSwitch(HSwitch node) {
-    // Switches are handled using [visitSwitchInfo].
-  }
-
-  void visitStatic(HStatic node) {
-    Element element = node.element;
-    if (element.isFunction) {
-      push(backend.namer.isolateStaticClosureAccess(node.element));
-    } else {
-      push(backend.namer.elementAccess(node.element));
-    }
-    registry.registerStaticUse(element);
-  }
-
-  void visitLazyStatic(HLazyStatic node) {
-    Element element = node.element;
-    registry.registerStaticUse(element);
-    js.Expression lazyGetter =
-        backend.namer.isolateLazyInitializerAccess(element);
-    js.Call call = new js.Call(lazyGetter, <js.Expression>[]);
-    push(call, node);
-  }
-
-  void visitStaticStore(HStaticStore node) {
-    registry.registerStaticUse(node.element);
-    js.Node variable = backend.namer.elementAccess(node.element);
-    use(node.inputs[0]);
-    push(new js.Assignment(variable, pop()), node);
-  }
-
-  void visitStringConcat(HStringConcat node) {
-    use(node.left);
-    js.Expression jsLeft = pop();
-    use(node.right);
-    push(new js.Binary('+', jsLeft, pop()), node);
-  }
-
-  void visitStringify(HStringify node) {
-    HInstruction input = node.inputs.first;
-    if (input.isString(compiler)) {
-      use(input);
-    } else if (input.isInteger(compiler) || input.isBoolean(compiler)) {
-      // JavaScript's + operator with a string for the left operand will convert
-      // the right operand to a string, and the conversion result is correct.
-      use(input);
-      if (node.usedBy.length == 1
-          && node.usedBy[0] is HStringConcat
-          && node.usedBy[0].inputs[1] == node) {
-        // The context is already <string> + value.
-      } else {
-        // Force an empty string for the first operand.
-        push(new js.Binary('+', js.string(""), pop()), node);
-      }
-    } else {
-      Element convertToString = backend.getStringInterpolationHelper();
-      registry.registerStaticUse(convertToString);
-      js.Expression jsHelper = backend.namer.elementAccess(convertToString);
-      use(input);
-      push(new js.Call(jsHelper, <js.Expression>[pop()]), node);
-    }
-  }
-
-  void visitLiteralList(HLiteralList node) {
-    registry.registerInstantiatedClass(compiler.listClass);
-    generateArrayLiteral(node);
-  }
-
-  void generateArrayLiteral(HLiteralList node) {
-    int len = node.inputs.length;
-    List<js.ArrayElement> elements = <js.ArrayElement>[];
-    for (int i = 0; i < len; i++) {
-      use(node.inputs[i]);
-      elements.add(new js.ArrayElement(i, pop()));
-    }
-    push(new js.ArrayInitializer(len, elements), node);
-  }
-
-  void visitIndex(HIndex node) {
-    use(node.receiver);
-    js.Expression receiver = pop();
-    use(node.index);
-    push(new js.PropertyAccess(receiver, pop()), node);
-  }
-
-  void visitIndexAssign(HIndexAssign node) {
-    use(node.receiver);
-    js.Expression receiver = pop();
-    use(node.index);
-    js.Expression index = pop();
-    use(node.value);
-    push(new js.Assignment(new js.PropertyAccess(receiver, index), pop()),
-         node);
-  }
-
-  void checkInt(HInstruction input, String cmp) {
-    use(input);
-    js.Expression left = pop();
-    use(input);
-    js.Expression or0 = new js.Binary("|", pop(), new js.LiteralNumber("0"));
-    push(new js.Binary(cmp, left, or0));
-  }
-
-  void checkBigInt(HInstruction input, String cmp) {
-    use(input);
-    js.Expression left = pop();
-    use(input);
-    js.Expression right = pop();
-    // TODO(4984): Deal with infinity and -0.0.
-    push(js.js('Math.floor(#) $cmp #', <js.Expression>[left, right]));
-  }
-
-  void checkTypeOf(HInstruction input, String cmp, String typeName) {
-    use(input);
-    js.Expression typeOf = new js.Prefix("typeof", pop());
-    push(new js.Binary(cmp, typeOf, js.string(typeName)));
-  }
-
-  void checkNum(HInstruction input, String cmp)
-      => checkTypeOf(input, cmp, 'number');
-
-  void checkDouble(HInstruction input, String cmp)  => checkNum(input, cmp);
-
-  void checkString(HInstruction input, String cmp)
-      => checkTypeOf(input, cmp, 'string');
-
-  void checkBool(HInstruction input, String cmp)
-      => checkTypeOf(input, cmp, 'boolean');
-
-  void checkObject(HInstruction input, String cmp) {
-    assert(NullConstantValue.JsNull == 'null');
-    if (cmp == "===") {
-      checkTypeOf(input, '===', 'object');
-      js.Expression left = pop();
-      use(input);
-      js.Expression notNull = new js.Binary("!==", pop(), new js.LiteralNull());
-      push(new js.Binary("&&", left, notNull));
-    } else {
-      assert(cmp == "!==");
-      checkTypeOf(input, '!==', 'object');
-      js.Expression left = pop();
-      use(input);
-      js.Expression eqNull = new js.Binary("===", pop(), new js.LiteralNull());
-      push(new js.Binary("||", left, eqNull));
-    }
-  }
-
-  void checkArray(HInstruction input, String cmp) {
-    use(input);
-    js.PropertyAccess constructor =
-        new js.PropertyAccess.field(pop(), 'constructor');
-    push(new js.Binary(cmp, constructor, new js.VariableUse('Array')));
-  }
-
-  void checkFieldExists(HInstruction input, String fieldName) {
-    use(input);
-    js.PropertyAccess field = new js.PropertyAccess.field(pop(), fieldName);
-    // Double negate to boolify the result.
-    push(new js.Prefix('!', new js.Prefix('!', field)));
-  }
-
-  void checkFieldDoesNotExist(HInstruction input, String fieldName) {
-    use(input);
-    js.PropertyAccess field = new js.PropertyAccess.field(pop(), fieldName);
-    push(new js.Prefix('!', field));
-  }
-
-  void checkImmutableArray(HInstruction input) {
-    checkFieldExists(input, 'immutable\$list');
-  }
-
-  void checkMutableArray(HInstruction input) {
-    checkFieldDoesNotExist(input, 'immutable\$list');
-  }
-
-  void checkExtendableArray(HInstruction input) {
-    checkFieldDoesNotExist(input, 'fixed\$length');
-  }
-
-  void checkFixedArray(HInstruction input) {
-    checkFieldExists(input, 'fixed\$length');
-  }
-
-  void checkNull(HInstruction input) {
-    use(input);
-    push(new js.Binary('==', pop(), new js.LiteralNull()));
-  }
-
-  void checkNonNull(HInstruction input) {
-    use(input);
-    push(new js.Binary('!=', pop(), new js.LiteralNull()));
-  }
-
-  bool checkIndexingBehavior(HInstruction input, {bool negative: false}) {
-    if (!compiler.resolverWorld.isInstantiated(
-          backend.jsIndexingBehaviorInterface)) {
-      return false;
-    }
-
-    use(input);
-    js.Expression object1 = pop();
-    use(input);
-    js.Expression object2 = pop();
-    push(backend.generateIsJsIndexableCall(object1, object2));
-    if (negative) push(new js.Prefix('!', pop()));
-    return true;
-  }
-
-  void checkType(HInstruction input, HInstruction interceptor,
-                 DartType type, {bool negative: false}) {
-    Element element = type.element;
-    if (element == backend.jsArrayClass) {
-      checkArray(input, negative ? '!==': '===');
-      return;
-    } else if (element == backend.jsMutableArrayClass) {
-      if (negative) {
-        checkImmutableArray(input);
-      } else {
-        checkMutableArray(input);
-      }
-      return;
-    } else if (element == backend.jsExtendableArrayClass) {
-      if (negative) {
-        checkFixedArray(input);
-      } else {
-        checkExtendableArray(input);
-      }
-      return;
-    } else if (element == backend.jsFixedArrayClass) {
-      if (negative) {
-        checkExtendableArray(input);
-      } else {
-        checkFixedArray(input);
-      }
-      return;
-    }
-    if (interceptor != null) {
-      checkTypeViaProperty(interceptor, type, negative);
-    } else {
-      checkTypeViaProperty(input, type, negative);
-    }
-  }
-
-  void checkTypeViaProperty(HInstruction input, DartType type, bool negative) {
-    registry.registerIsCheck(type);
-
-    use(input);
-
-    js.PropertyAccess field =
-        new js.PropertyAccess.field(pop(), backend.namer.operatorIsType(type));
-    // We always negate at least once so that the result is boolified.
-    push(new js.Prefix('!', field));
-    // If the result is not negated, put another '!' in front.
-    if (!negative) push(new js.Prefix('!', pop()));
-  }
-
-  void handleNumberOrStringSupertypeCheck(HInstruction input,
-                                          HInstruction interceptor,
-                                          DartType type,
-                                          { bool negative: false }) {
-    assert(!identical(type.element, compiler.listClass)
-           && !Elements.isListSupertype(type.element, compiler)
-           && !Elements.isStringOnlySupertype(type.element, compiler));
-    String relation = negative ? '!==' : '===';
-    checkNum(input, relation);
-    js.Expression numberTest = pop();
-    checkString(input, relation);
-    js.Expression stringTest = pop();
-    checkObject(input, relation);
-    js.Expression objectTest = pop();
-    checkType(input, interceptor, type, negative: negative);
-    String combiner = negative ? '&&' : '||';
-    String combiner2 = negative ? '||' : '&&';
-    push(new js.Binary(combiner,
-                       new js.Binary(combiner, numberTest, stringTest),
-                       new js.Binary(combiner2, objectTest, pop())));
-  }
-
-  void handleStringSupertypeCheck(HInstruction input,
-                                  HInstruction interceptor,
-                                  DartType type,
-                                  { bool negative: false }) {
-    assert(!identical(type.element, compiler.listClass)
-           && !Elements.isListSupertype(type.element, compiler)
-           && !Elements.isNumberOrStringSupertype(type.element, compiler));
-    String relation = negative ? '!==' : '===';
-    checkString(input, relation);
-    js.Expression stringTest = pop();
-    checkObject(input, relation);
-    js.Expression objectTest = pop();
-    checkType(input, interceptor, type, negative: negative);
-    String combiner = negative ? '||' : '&&';
-    push(new js.Binary(negative ? '&&' : '||',
-                       stringTest,
-                       new js.Binary(combiner, objectTest, pop())));
-  }
-
-  void handleListOrSupertypeCheck(HInstruction input,
-                                  HInstruction interceptor,
-                                  DartType type,
-                                  { bool negative: false }) {
-    assert(!identical(type.element, compiler.stringClass)
-           && !Elements.isStringOnlySupertype(type.element, compiler)
-           && !Elements.isNumberOrStringSupertype(type.element, compiler));
-    String relation = negative ? '!==' : '===';
-    checkObject(input, relation);
-    js.Expression objectTest = pop();
-    checkArray(input, relation);
-    js.Expression arrayTest = pop();
-    checkType(input, interceptor, type, negative: negative);
-    String combiner = negative ? '&&' : '||';
-    push(new js.Binary(negative ? '||' : '&&',
-                       objectTest,
-                       new js.Binary(combiner, arrayTest, pop())));
-  }
-
-  void visitIs(HIs node) {
-    emitIs(node, "===");
-  }
-
-  void visitIsViaInterceptor(HIsViaInterceptor node) {
-    emitIsViaInterceptor(node, false);
-  }
-
-  void emitIs(HIs node, String relation)  {
-    DartType type = node.typeExpression;
-    registry.registerIsCheck(type);
-    HInstruction input = node.expression;
-
-    // If this is changed to single == there are several places below that must
-    // be changed to match.
-    assert(relation == '===' || relation == '!==');
-    bool negative = relation == '!==';
-
-    if (node.isVariableCheck || node.isCompoundCheck) {
-      use(node.checkCall);
-      if (negative) push(new js.Prefix('!', pop()));
-    } else {
-      assert(node.isRawCheck);
-      HInstruction interceptor = node.interceptor;
-      LibraryElement coreLibrary = compiler.coreLibrary;
-      ClassElement objectClass = compiler.objectClass;
-      Element element = type.element;
-      if (element == compiler.nullClass) {
-        if (negative) {
-          checkNonNull(input);
-        } else {
-          checkNull(input);
-        }
-      } else if (identical(element, objectClass) || type.treatAsDynamic) {
-        // The constant folder also does this optimization, but we make
-        // it safe by assuming it may have not run.
-        push(newLiteralBool(!negative), node);
-      } else if (element == compiler.stringClass) {
-        checkString(input, relation);
-        attachLocationToLast(node);
-      } else if (element == compiler.doubleClass) {
-        checkDouble(input, relation);
-        attachLocationToLast(node);
-      } else if (element == compiler.numClass) {
-        checkNum(input, relation);
-        attachLocationToLast(node);
-      } else if (element == compiler.boolClass) {
-        checkBool(input, relation);
-        attachLocationToLast(node);
-      } else if (element == compiler.intClass) {
-        // The is check in the code tells us that it might not be an
-        // int. So we do a typeof first to avoid possible
-        // deoptimizations on the JS engine due to the Math.floor check.
-        checkNum(input, relation);
-        js.Expression numTest = pop();
-        checkBigInt(input, relation);
-        push(new js.Binary(negative ? '||' : '&&', numTest, pop()), node);
-      } else if (Elements.isNumberOrStringSupertype(element, compiler)) {
-        handleNumberOrStringSupertypeCheck(
-            input, interceptor, type, negative: negative);
-        attachLocationToLast(node);
-      } else if (Elements.isStringOnlySupertype(element, compiler)) {
-        handleStringSupertypeCheck(
-            input, interceptor, type, negative: negative);
-        attachLocationToLast(node);
-      } else if (identical(element, compiler.listClass)
-                 || Elements.isListSupertype(element, compiler)) {
-        handleListOrSupertypeCheck(
-            input, interceptor, type, negative: negative);
-        attachLocationToLast(node);
-      } else if (type.isFunctionType) {
-        checkType(input, interceptor, type, negative: negative);
-        attachLocationToLast(node);
-      } else if ((input.canBePrimitive(compiler)
-                  && !input.canBePrimitiveArray(compiler))
-                 || input.canBeNull()) {
-        checkObject(input, relation);
-        js.Expression objectTest = pop();
-        checkType(input, interceptor, type, negative: negative);
-        push(new js.Binary(negative ? '||' : '&&', objectTest, pop()), node);
-      } else {
-        checkType(input, interceptor, type, negative: negative);
-        attachLocationToLast(node);
-      }
-    }
-  }
-
-  void emitIsViaInterceptor(HIsViaInterceptor node, bool negative) {
-    checkTypeViaProperty(node.interceptor, node.typeExpression, negative);
-    attachLocationToLast(node);
-  }
-
-  js.Expression generateTest(HInstruction input, TypeMask checkedType) {
-    ClassWorld classWorld = compiler.world;
-    TypeMask receiver = input.instructionType;
-    // Figure out if it is beneficial to turn this into a null check.
-    // V8 generally prefers 'typeof' checks, but for integers and
-    // indexable primitives we cannot compile this test into a single
-    // typeof check so the null check is cheaper.
-    bool turnIntoNumCheck = input.isIntegerOrNull(compiler)
-        && checkedType.containsOnlyInt(classWorld);
-    bool turnIntoNullCheck = !turnIntoNumCheck
-        && (checkedType.nullable() == receiver)
-        && (checkedType.containsOnlyInt(classWorld)
-            || checkedType.satisfies(backend.jsIndexableClass, classWorld));
-    js.Expression test;
-    if (turnIntoNullCheck) {
-      use(input);
-      test = new js.Binary("==", pop(), new js.LiteralNull());
-    } else if (checkedType.containsOnlyInt(classWorld) && !turnIntoNumCheck) {
-      // input is !int
-      checkInt(input, '!==');
-      test = pop();
-    } else if (checkedType.containsOnlyNum(classWorld) || turnIntoNumCheck) {
-      // input is !num
-      checkNum(input, '!==');
-      test = pop();
-    } else if (checkedType.containsOnlyBool(classWorld)) {
-      // input is !bool
-      checkBool(input, '!==');
-      test = pop();
-    } else if (checkedType.containsOnlyString(classWorld)) {
-      // input is !string
-      checkString(input, '!==');
-      test = pop();
-    } else if (checkedType.satisfies(backend.jsExtendableArrayClass,
-                                     classWorld)) {
-      // input is !Object || input is !Array || input.isFixed
-      checkObject(input, '!==');
-      js.Expression objectTest = pop();
-      checkArray(input, '!==');
-      js.Expression arrayTest = pop();
-      checkFixedArray(input);
-      test = new js.Binary('||', objectTest, arrayTest);
-      test = new js.Binary('||', test, pop());
-    } else if (checkedType.satisfies(backend.jsMutableArrayClass, classWorld)) {
-      // input is !Object
-      // || ((input is !Array || input.isImmutable)
-      //     && input is !JsIndexingBehavior)
-      checkObject(input, '!==');
-      js.Expression objectTest = pop();
-      checkArray(input, '!==');
-      js.Expression arrayTest = pop();
-      checkImmutableArray(input);
-      js.Binary notArrayOrImmutable = new js.Binary('||', arrayTest, pop());
-
-      js.Binary notIndexing = checkIndexingBehavior(input, negative: true)
-          ? new js.Binary('&&', notArrayOrImmutable, pop())
-          : notArrayOrImmutable;
-      test = new js.Binary('||', objectTest, notIndexing);
-    } else if (checkedType.satisfies(backend.jsArrayClass, classWorld)) {
-      // input is !Object
-      // || (input is !Array && input is !JsIndexingBehavior)
-      checkObject(input, '!==');
-      js.Expression objectTest = pop();
-      checkArray(input, '!==');
-      js.Expression arrayTest = pop();
-
-      js.Expression notIndexing = checkIndexingBehavior(input, negative: true)
-          ? new js.Binary('&&', arrayTest, pop())
-          : arrayTest;
-      test = new js.Binary('||', objectTest, notIndexing);
-    } else if (checkedType.satisfies(backend.jsIndexableClass, classWorld)) {
-      // input is !String
-      // && (input is !Object
-      //     || (input is !Array && input is !JsIndexingBehavior))
-      checkString(input, '!==');
-      js.Expression stringTest = pop();
-      checkObject(input, '!==');
-      js.Expression objectTest = pop();
-      checkArray(input, '!==');
-      js.Expression arrayTest = pop();
-
-      js.Binary notIndexingTest = checkIndexingBehavior(input, negative: true)
-          ? new js.Binary('&&', arrayTest, pop())
-          : arrayTest;
-      js.Binary notObjectOrIndexingTest =
-          new js.Binary('||', objectTest, notIndexingTest);
-      test = new js.Binary('&&', stringTest, notObjectOrIndexingTest);
-    } else {
-      compiler.internalError(input, 'Unexpected check.');
-    }
-    return test;
-  }
-
-  void visitTypeConversion(HTypeConversion node) {
-    if (node.isArgumentTypeCheck || node.isReceiverTypeCheck) {
-      ClassWorld classWorld = compiler.world;
-      // An int check if the input is not int or null, is not
-      // sufficient for doing a argument or receiver check.
-      assert(!node.checkedType.containsOnlyInt(classWorld) ||
-             node.checkedInput.isIntegerOrNull(compiler));
-      js.Expression test = generateTest(node.checkedInput, node.checkedType);
-      js.Block oldContainer = currentContainer;
-      js.Statement body = new js.Block.empty();
-      currentContainer = body;
-      if (node.isArgumentTypeCheck) {
-        generateThrowWithHelper('iae', node.checkedInput);
-      } else if (node.isReceiverTypeCheck) {
-        use(node.checkedInput);
-        String methodName =
-            backend.namer.invocationName(node.receiverTypeCheckSelector);
-        js.Expression call = jsPropertyCall(pop(), methodName, []);
-        pushStatement(new js.Return(call));
-      }
-      currentContainer = oldContainer;
-      body = unwrapStatement(body);
-      pushStatement(new js.If.noElse(test, body), node);
-      return;
-    }
-
-    assert(node.isCheckedModeCheck || node.isCastTypeCheck);
-    DartType type = node.typeExpression;
-    assert(type.kind != TypeKind.TYPEDEF);
-    if (type.isFunctionType) {
-      // TODO(5022): We currently generate $isFunction checks for
-      // function types.
-      registry.registerIsCheck(compiler.functionClass.rawType);
-    }
-    registry.registerIsCheck(type);
-
-    CheckedModeHelper helper;
-    if (node.isBooleanConversionCheck) {
-      helper =
-          const CheckedModeHelper('boolConversionCheck');
-    } else {
-      helper =
-          backend.getCheckedModeHelper(type, typeCast: node.isCastTypeCheck);
-    }
-
-    if (helper == null) {
-      assert(type.isFunctionType);
-      use(node.inputs[0]);
-    } else {
-      push(helper.generateCall(this, node));
-    }
-  }
-
-  void visitTypeKnown(HTypeKnown node) {
-    // [HTypeKnown] instructions are removed before generating code.
-    assert(false);
-  }
-
-  void visitFunctionType(HFunctionType node) {
-    FunctionType type = node.dartType;
-    int inputCount = 0;
-    use(node.inputs[inputCount++]);
-    js.Expression returnType = pop();
-
-    List<js.Expression> parameterTypes = <js.Expression>[];
-    for (var _ in type.parameterTypes) {
-      use(node.inputs[inputCount++]);
-      parameterTypes.add(pop());
-    }
-
-    List<js.Expression> optionalParameterTypes = <js.Expression>[];
-    for (var _ in type.optionalParameterTypes) {
-      use(node.inputs[inputCount++]);
-      optionalParameterTypes.add(pop());
-    }
-
-    List<js.Property> namedParameters = <js.Property>[];
-    for (var _ in type.namedParameters) {
-      use(node.inputs[inputCount++]);
-      js.Expression name = pop();
-      use(node.inputs[inputCount++]);
-      namedParameters.add(new js.Property(name, pop()));
-    }
-
-    if (namedParameters.isEmpty) {
-      var arguments = [returnType];
-      if (!parameterTypes.isEmpty || !optionalParameterTypes.isEmpty) {
-        arguments.add(new js.ArrayInitializer.from(parameterTypes));
-      }
-      if (!optionalParameterTypes.isEmpty) {
-        arguments.add(new js.ArrayInitializer.from(optionalParameterTypes));
-      }
-      push(js.js('#(#)', [accessHelper('buildFunctionType'), arguments]));
-    } else {
-      var arguments = [
-          returnType,
-          new js.ArrayInitializer.from(parameterTypes),
-          new js.ObjectInitializer(namedParameters)];
-      push(js.js('#(#)', [accessHelper('buildNamedFunctionType'), arguments]));
-    }
-  }
-
-  void visitReadTypeVariable(HReadTypeVariable node) {
-    TypeVariableElement element = node.dartType.element;
-    Element helperElement = backend.findHelper('convertRtiToRuntimeType');
-    registry.registerStaticUse(helperElement);
-
-    use(node.inputs[0]);
-    if (node.hasReceiver) {
-      if (backend.isInterceptorClass(element.enclosingClass)) {
-        int index = RuntimeTypes.getTypeVariableIndex(element);
-        js.Expression receiver = pop();
-        js.Expression helper = backend.namer.elementAccess(helperElement);
-        push(js.js(r'#(#.$builtinTypeInfo && #.$builtinTypeInfo[#])',
-                [helper, receiver, receiver, js.js.number(index)]));
-      } else {
-        backend.emitter.registerReadTypeVariable(element);
-        push(js.js('#.#()',
-                [pop(), backend.namer.readTypeVariableName(element)]));
-      }
-    } else {
-      push(js.js('#(#)', [
-          backend.namer.elementAccess(
-              backend.findHelper('convertRtiToRuntimeType')),
-          pop()]));
-    }
-  }
-
-  void visitInterfaceType(HInterfaceType node) {
-    List<js.Expression> typeArguments = <js.Expression>[];
-    for (HInstruction type in node.inputs) {
-      use(type);
-      typeArguments.add(pop());
-    }
-
-    ClassElement cls = node.dartType.element;
-    var arguments = [backend.namer.elementAccess(cls)];
-    if (!typeArguments.isEmpty) {
-      arguments.add(new js.ArrayInitializer.from(typeArguments));
-    }
-    push(js.js('#(#)', [accessHelper('buildInterfaceType'), arguments]));
-  }
-
-  void visitVoidType(HVoidType node) {
-    push(js.js('#()', accessHelper('getVoidRuntimeType')));
-  }
-
-  void visitDynamicType(HDynamicType node) {
-    push(js.js('#()', accessHelper('getDynamicRuntimeType')));
-  }
-
-  js.PropertyAccess accessHelper(String name) {
-    Element helper = backend.findHelper(name);
-    if (helper == null) {
-      // For mocked-up tests.
-      return js.js('(void 0).$name');
-    }
-    registry.registerStaticUse(helper);
-    return backend.namer.elementAccess(helper);
-  }
-}