Merge CommonElements and BackendHelpers!

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

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:collection';
 
 import 'package:js_runtime/shared/embedded_names.dart';
 
 import '../closure.dart';
 import '../common.dart';
 import '../common/codegen.dart' show CodegenRegistry, CodegenWorkItem;
 import '../common/names.dart' show Identifiers, Selectors;
 import '../common/tasks.dart' show CompilerTask;
 import '../constants/constant_system.dart';
 import '../constants/expressions.dart';
 import '../constants/values.dart';
 import '../elements/resolution_types.dart';
 import '../elements/types.dart';
 import '../diagnostics/messages.dart' show Message, MessageTemplate;
 import '../dump_info.dart' show InfoReporter;
 import '../elements/elements.dart';
 import '../elements/entities.dart';
 import '../elements/modelx.dart' show ConstructorBodyElementX;
 import '../io/source_information.dart';
 import '../js/js.dart' as js;
-import '../js_backend/backend_helpers.dart' show BackendHelpers;
+import '../js_backend/backend.dart' show JavaScriptBackend;
 import '../js_backend/js_backend.dart';
 import '../js_emitter/js_emitter.dart' show CodeEmitterTask, NativeEmitter;
 import '../native/native.dart' as native;
 import '../resolution/operators.dart';
 import '../resolution/semantic_visitor.dart';
 import '../resolution/tree_elements.dart' show TreeElements;
 import '../tree/tree.dart' as ast;
 import '../types/types.dart';
 import '../universe/call_structure.dart' show CallStructure;
 import '../universe/selector.dart' show Selector;
@@ skipping 663 matching lines @@
             },
             visitElse: null,
             sourceInformation: sourceInformationBuilder.buildIf(function.body));
       }
     }
     if (const bool.fromEnvironment('unreachable-throw')) {
       var emptyParameters =
           parameters.values.where((p) => p.instructionType.isEmpty);
       if (emptyParameters.length > 0) {
         addComment('${emptyParameters} inferred as [empty]');
-        pushInvokeStatic(function.body, helpers.assertUnreachableMethod, []);
+        pushInvokeStatic(
+            function.body, commonElements.assertUnreachableMethod, []);
         pop();
         return closeFunction();
       }
     }
     function.body.accept(this);
     return closeFunction();
   }
 
   /// Adds a JavaScript comment to the output. The comment will be omitted in
   /// minified mode.  Each line in [text] is preceded with `//` and indented.
@@ skipping 706 matching lines @@
       // Otherwise it is a lazy initializer which does not have parameters.
       assert(element is VariableElement);
     }
 
     insertTraceCall(element);
     insertCoverageCall(element);
   }
 
   insertTraceCall(Element element) {
     if (JavaScriptBackend.TRACE_METHOD == 'console') {
-      if (element == helpers.traceHelper) return;
+      if (element == commonElements.traceHelper) return;
       n(e) => e == null ? '' : e.name;
       String name = "${n(element.library)}:${n(element.enclosingClass)}."
           "${n(element)}";
       HConstant nameConstant = addConstantString(name);
-      add(new HInvokeStatic(helpers.traceHelper, <HInstruction>[nameConstant],
-          commonMasks.dynamicType));
+      add(new HInvokeStatic(commonElements.traceHelper,
+          <HInstruction>[nameConstant], commonMasks.dynamicType));
     }
   }
 
   insertCoverageCall(Element element) {
     if (JavaScriptBackend.TRACE_METHOD == 'post') {
-      if (element == helpers.traceHelper) return;
+      if (element == commonElements.traceHelper) return;
       // TODO(sigmund): create a better uuid for elements.
       HConstant idConstant =
           graph.addConstantInt(element.hashCode, closedWorld);
       HConstant nameConstant = addConstantString(element.name);
-      add(new HInvokeStatic(helpers.traceHelper,
+      add(new HInvokeStatic(commonElements.traceHelper,
           <HInstruction>[idConstant, nameConstant], commonMasks.dynamicType));
     }
   }
 
   void assertIsSubtype(ast.Node node, ResolutionDartType subtype,
       ResolutionDartType supertype, String message) {
     HInstruction subtypeInstruction = typeBuilder.analyzeTypeArgument(
         localsHandler.substInContext(subtype), sourceElement);
     HInstruction supertypeInstruction = typeBuilder.analyzeTypeArgument(
         localsHandler.substInContext(supertype), sourceElement);
     HInstruction messageInstruction = graph.addConstantString(
         new ast.DartString.literal(message), closedWorld);
-    MethodElement element = helpers.assertIsSubtype;
+    MethodElement element = commonElements.assertIsSubtype;
     var inputs = <HInstruction>[
       subtypeInstruction,
       supertypeInstruction,
       messageInstruction
     ];
     HInstruction assertIsSubtype =
         new HInvokeStatic(element, inputs, subtypeInstruction.instructionType);
     registry?.registerTypeVariableBoundsSubtypeCheck(subtype, supertype);
     add(assertIsSubtype);
   }
@@ skipping 44 matching lines @@
 
   visitAssert(ast.Assert node) {
     if (!options.enableUserAssertions) return;
 
     if (!node.hasMessage) {
       // Generate:
       //
       //     assertHelper(condition);
       //
       visit(node.condition);
-      pushInvokeStatic(node, helpers.assertHelper, [pop()]);
+      pushInvokeStatic(node, commonElements.assertHelper, [pop()]);
       pop();
       return;
     }
     // Assert has message. Generate:
     //
     //     if (assertTest(condition)) assertThrow(message);
     //
     void buildCondition() {
       visit(node.condition);
-      pushInvokeStatic(node, helpers.assertTest, [pop()]);
+      pushInvokeStatic(node, commonElements.assertTest, [pop()]);
     }
 
     void fail() {
       visit(node.message);
-      pushInvokeStatic(node, helpers.assertThrow, [pop()]);
+      pushInvokeStatic(node, commonElements.assertThrow, [pop()]);
       pop();
     }
 
     handleIf(node: node, visitCondition: buildCondition, visitThen: fail);
   }
 
   visitBlock(ast.Block node) {
     assert(!isAborted());
     if (!isReachable) return; // This can only happen when inlining.
     for (Link<ast.Node> link = node.statements.nodes;
@@ skipping 462 matching lines @@
   /// Inserts a call to checkDeferredIsLoaded for [prefixElement].
   /// If [prefixElement] is [null] ndo nothing.
   void generateIsDeferredLoadedCheckIfNeeded(
       PrefixElement prefixElement, ast.Node location) {
     if (prefixElement == null) return;
     String loadId =
         compiler.deferredLoadTask.getImportDeferName(location, prefixElement);
     HInstruction loadIdConstant = addConstantString(loadId);
     String uri = prefixElement.deferredImport.uri.toString();
     HInstruction uriConstant = addConstantString(uri);
-    MethodElement helper = helpers.checkDeferredIsLoaded;
+    MethodElement helper = commonElements.checkDeferredIsLoaded;
     pushInvokeStatic(location, helper, [loadIdConstant, uriConstant]);
     pop();
   }
 
   /// Inserts a call to checkDeferredIsLoaded if the send has a prefix that
   /// resolves to a deferred library.
   void generateIsDeferredLoadedCheckOfSend(ast.Send node) {
     generateIsDeferredLoadedCheckIfNeeded(
         compiler.deferredLoadTask.deferredPrefixElement(node, elements), node);
   }
@@ skipping 345 matching lines @@
       generateTypeError(node, message);
       HInstruction call = pop();
       return new HIs.compound(type, expression, call, commonMasks.boolType);
     } else if (type.isFunctionType) {
       HInstruction representation =
           typeBuilder.analyzeTypeArgument(type, sourceElement);
       List<HInstruction> inputs = <HInstruction>[
         expression,
         representation,
       ];
-      pushInvokeStatic(node, helpers.functionTypeTest, inputs,
+      pushInvokeStatic(node, commonElements.functionTypeTest, inputs,
           typeMask: commonMasks.boolType);
       HInstruction call = pop();
       return new HIs.compound(type, expression, call, commonMasks.boolType);
     } else if (type.isTypeVariable) {
       HInstruction runtimeType =
           typeBuilder.addTypeVariableReference(type, sourceElement);
-      MethodElement helper = helpers.checkSubtypeOfRuntimeType;
+      MethodElement helper = commonElements.checkSubtypeOfRuntimeType;
       List<HInstruction> inputs = <HInstruction>[expression, runtimeType];
       pushInvokeStatic(null, helper, inputs, typeMask: commonMasks.boolType);
       HInstruction call = pop();
       return new HIs.variable(type, expression, call, commonMasks.boolType);
     } else if (RuntimeTypesSubstitutions.hasTypeArguments(type)) {
       ClassElement element = type.element;
-      MethodElement helper = helpers.checkSubtype;
+      MethodElement helper = commonElements.checkSubtype;
       HInstruction representations =
           typeBuilder.buildTypeArgumentRepresentations(type, sourceElement);
       add(representations);
       js.Name operator = namer.operatorIs(element);
       HInstruction isFieldName = addConstantStringFromName(operator);
       HInstruction asFieldName = closedWorld.hasAnyStrictSubtype(element)
           ? addConstantStringFromName(namer.substitutionName(element))
           : graph.addConstantNull(closedWorld);
       List<HInstruction> inputs = <HInstruction>[
         expression,
@@ skipping 243 matching lines @@
       // If the isolate library is not used, we just generate code
       // to fetch the static state.
       String name = namer.staticStateHolder;
       push(new HForeignCode(
           js.js.parseForeignJS(name), commonMasks.dynamicType, <HInstruction>[],
           nativeBehavior: native.NativeBehavior.DEPENDS_OTHER));
     } else {
       // Call a helper method from the isolate library. The isolate
       // library uses its own isolate structure, that encapsulates
       // Leg's isolate.
-      MethodElement element = helpers.currentIsolate;
+      MethodElement element = commonElements.currentIsolate;
       if (element == null) {
         reporter.internalError(node, 'Isolate library and compiler mismatch.');
       }
       pushInvokeStatic(null, element, [], typeMask: commonMasks.dynamicType);
     }
   }
 
   void handleForeignJsGetFlag(ast.Send node) {
     List<ast.Node> arguments = node.arguments.toList();
     ast.Node argument;
@@ skipping 47 matching lines @@
       default:
         for (int i = 1; i < arguments.length; i++) {
           reporter.reportErrorMessage(arguments[i], MessageKind.GENERIC,
               {'text': 'Error: Extra argument to JS_GET_NAME.'});
         }
         return;
     }
     Element element = elements[argument];
     if (element == null ||
         element is! EnumConstantElement ||
-        element.enclosingClass != helpers.jsGetNameEnum) {
+        element.enclosingClass != commonElements.jsGetNameEnum) {
       reporter.reportErrorMessage(argument, MessageKind.GENERIC,
           {'text': 'Error: Expected a JsGetName enum value.'});
     }
     EnumConstantElement enumConstant = element;
     int index = enumConstant.index;
     stack.add(addConstantStringFromName(
         namer.getNameForJsGetName(argument, JsGetName.values[index])));
   }
 
   void handleForeignJsBuiltin(ast.Send node) {
     List<ast.Node> arguments = node.arguments.toList();
     ast.Node argument;
     if (arguments.length < 2) {
       reporter.reportErrorMessage(node, MessageKind.GENERIC,
           {'text': 'Error: Expected at least two arguments to JS_BUILTIN.'});
     }
 
     Element builtinElement = elements[arguments[1]];
     if (builtinElement == null ||
         (builtinElement is! EnumConstantElement) ||
-        builtinElement.enclosingClass != helpers.jsBuiltinEnum) {
+        builtinElement.enclosingClass != commonElements.jsBuiltinEnum) {
       reporter.reportErrorMessage(argument, MessageKind.GENERIC,
           {'text': 'Error: Expected a JsBuiltin enum value.'});
     }
     EnumConstantElement enumConstant = builtinElement;
     int index = enumConstant.index;
 
     js.Template template = emitter.builtinTemplateFor(JsBuiltin.values[index]);
 
     List<HInstruction> compiledArguments = <HInstruction>[];
     for (int i = 2; i < arguments.length; i++) {
@@ skipping 83 matching lines @@
   void handleForeignJsCallInIsolate(ast.Send node) {
     Link<ast.Node> link = node.arguments;
     if (!backendUsage.isIsolateInUse) {
       // If the isolate library is not used, we just invoke the
       // closure.
       visit(link.tail.head);
       push(new HInvokeClosure(new Selector.callClosure(0),
           <HInstruction>[pop()], commonMasks.dynamicType));
     } else {
       // Call a helper method from the isolate library.
-      MethodElement element = helpers.callInIsolate;
+      MethodElement element = commonElements.callInIsolate;
       if (element == null) {
         reporter.internalError(node, 'Isolate library and compiler mismatch.');
       }
       List<HInstruction> inputs = <HInstruction>[];
       addGenericSendArgumentsToList(link, inputs);
       pushInvokeStatic(node, element, inputs,
           typeMask: commonMasks.dynamicType);
     }
   }
 
@@ skipping 55 matching lines @@
     if (!node.arguments.isEmpty) {
       reporter.internalError(node.argumentsNode, 'Too many arguments.');
     }
     push(new HForeignCode(js.js.parseForeignJS(namer.staticStateHolder),
         commonMasks.dynamicType, <HInstruction>[],
         nativeBehavior: native.NativeBehavior.DEPENDS_OTHER));
   }
 
   void handleForeignSend(ast.Send node, FunctionElement element) {
     String name = element.name;
-    if (name == BackendHelpers.JS) {
+    if (name == JavaScriptBackend.JS) {
       handleForeignJs(node);
     } else if (name == 'JS_CURRENT_ISOLATE_CONTEXT') {
       handleForeignJsCurrentIsolateContext(node);
     } else if (name == 'JS_CALL_IN_ISOLATE') {
       handleForeignJsCallInIsolate(node);
     } else if (name == 'DART_CLOSURE_TO_JS') {
       handleForeignDartClosureToJs(node, 'DART_CLOSURE_TO_JS');
     } else if (name == 'RAW_DART_FUNCTION_REF') {
       handleForeignRawFunctionRef(node, 'RAW_DART_FUNCTION_REF');
     } else if (name == 'JS_SET_STATIC_STATE') {
       handleForeignJsSetStaticState(node);
     } else if (name == 'JS_GET_STATIC_STATE') {
       handleForeignJsGetStaticState(node);
     } else if (name == 'JS_GET_NAME') {
       handleForeignJsGetName(node);
-    } else if (name == BackendHelpers.JS_EMBEDDED_GLOBAL) {
+    } else if (name == JavaScriptBackend.JS_EMBEDDED_GLOBAL) {
       handleForeignJsEmbeddedGlobal(node);
-    } else if (name == BackendHelpers.JS_BUILTIN) {
+    } else if (name == JavaScriptBackend.JS_BUILTIN) {
       handleForeignJsBuiltin(node);
     } else if (name == 'JS_GET_FLAG') {
       handleForeignJsGetFlag(node);
     } else if (name == 'JS_EFFECT') {
       stack.add(graph.addConstantNull(closedWorld));
-    } else if (name == BackendHelpers.JS_INTERCEPTOR_CONSTANT) {
+    } else if (name == JavaScriptBackend.JS_INTERCEPTOR_CONSTANT) {
       handleJsInterceptorConstant(node);
     } else if (name == 'JS_STRING_CONCAT') {
       handleJsStringConcat(node);
     } else {
       reporter.internalError(node, "Unknown foreign: ${element}");
     }
   }
 
   generateDeferredLoaderGet(ast.Send node, FunctionElement deferredLoader,
       SourceInformation sourceInformation) {
     // Until now we only handle these as getters.
     invariant(node, deferredLoader.isDeferredLoaderGetter);
-    FunctionEntity loadFunction = helpers.loadLibraryWrapper;
+    FunctionEntity loadFunction = commonElements.loadLibraryWrapper;
     PrefixElement prefixElement = deferredLoader.enclosingElement;
     String loadId =
         compiler.deferredLoadTask.getImportDeferName(node, prefixElement);
     var inputs = [
       graph.addConstantString(new ast.DartString.literal(loadId), closedWorld)
     ];
     push(new HInvokeStatic(loadFunction, inputs, commonMasks.nonNullType,
         targetCanThrow: false)
       ..sourceInformation = sourceInformation);
   }
@@ skipping 17 matching lines @@
       registry?.registerDynamicUse(new DynamicUse(selector, null));
     }
     String publicName = name;
     if (selector.isSetter) publicName += '=';
 
     ConstantValue nameConstant =
         constantSystem.createString(new ast.DartString.literal(publicName));
 
     js.Name internalName = namer.invocationName(selector);
 
-    MethodElement createInvocationMirror = helpers.createInvocationMirror;
+    MethodElement createInvocationMirror =
+        commonElements.createInvocationMirror;
     var argumentsInstruction = buildLiteralList(arguments);
     add(argumentsInstruction);
 
     var argumentNames = new List<HInstruction>();
     for (String argumentName in selector.namedArguments) {
       ConstantValue argumentNameConstant =
           constantSystem.createString(new ast.DartString.literal(argumentName));
       argumentNames.add(graph.addConstant(argumentNameConstant, closedWorld));
     }
     var argumentNamesInstruction = buildLiteralList(argumentNames);
@@ skipping 209 matching lines @@
       inputs.add(typeBuilder.analyzeTypeArgument(argument, sourceElement));
     });
     // TODO(15489): Register at codegen.
     registry?.registerInstantiation(type);
     return callSetRuntimeTypeInfoWithTypeArguments(type, inputs, newObject);
   }
 
   HInstruction callSetRuntimeTypeInfo(
       HInstruction typeInfo, HInstruction newObject) {
     // Set the runtime type information on the object.
-    MethodElement typeInfoSetterElement = helpers.setRuntimeTypeInfo;
+    MethodElement typeInfoSetterElement = commonElements.setRuntimeTypeInfo;
     pushInvokeStatic(
         null, typeInfoSetterElement, <HInstruction>[newObject, typeInfo],
         typeMask: commonMasks.dynamicType,
         sourceInformation: newObject.sourceInformation);
 
     // The new object will now be referenced through the
     // `setRuntimeTypeInfo` call. We therefore set the type of that
     // instruction to be of the object's type.
     assert(invariant(CURRENT_ELEMENT_SPANNABLE,
         stack.last is HInvokeStatic || stack.last == newObject,
@@ skipping 53 matching lines @@
       }
     }
 
     CallStructure callStructure = elements.getSelector(send).callStructure;
     ConstructorElement constructorDeclaration = constructor;
     ConstructorElement constructorImplementation = constructor.implementation;
     constructor = constructorImplementation.effectiveTarget;
 
     final bool isSymbolConstructor =
         closedWorld.commonElements.isSymbolConstructor(constructorDeclaration);
-    final bool isJSArrayTypedConstructor =
-        constructorDeclaration == helpers.jsArrayTypedConstructor;
+    final bool isJSArrayTypedConstructor = constructorDeclaration ==
+        closedWorld.commonElements.jsArrayTypedConstructor;
 
     if (isSymbolConstructor) {
-      constructor = helpers.symbolValidatedConstructor;
+      constructor = commonElements.symbolValidatedConstructor;
       assert(invariant(send, constructor != null,
           message: 'Constructor Symbol.validated is missing'));
-      callStructure = helpers.symbolValidatedConstructorSelector.callStructure;
+      callStructure =
+          commonElements.symbolValidatedConstructorSelector.callStructure;
       assert(invariant(send, callStructure != null,
           message: 'Constructor Symbol.validated is missing'));
     }
 
     bool isRedirected = constructorDeclaration.isRedirectingFactory;
     if (!constructorDeclaration.isCyclicRedirection) {
       // Insert a check for every deferred redirection on the path to the
       // final target.
       ConstructorElement target = constructorDeclaration;
       while (target.isRedirectingFactory) {
@@ skipping 406 matching lines @@
       ast.Send node, ResolutionTypeVariableType typeVariable) {
     // GENERIC_METHODS: This provides thin support for method type variables
     // by treating them as malformed when evaluated as a literal. For full
     // support of generic methods this must be revised.
     if (typeVariable is MethodTypeVariableType) {
       generateTypeError(node, "Method type variables are not reified");
     } else {
       ResolutionDartType type = localsHandler.substInContext(typeVariable);
       HInstruction value = typeBuilder.analyzeTypeArgument(type, sourceElement,
           sourceInformation: sourceInformationBuilder.buildGet(node));
-      pushInvokeStatic(node, helpers.runtimeTypeToString, [value],
+      pushInvokeStatic(node, commonElements.runtimeTypeToString, [value],
           typeMask: commonMasks.stringType);
-      pushInvokeStatic(node, helpers.createRuntimeType, [pop()]);
+      pushInvokeStatic(node, commonElements.createRuntimeType, [pop()]);
     }
   }
 
   /// Generate a call to a type literal.
   void generateTypeLiteralCall(ast.Send node) {
     // This send is of the form 'e(...)', where e is resolved to a type
     // reference. We create a regular closure call on the result of the type
     // reference instead of creating a NoSuchMethodError to avoid pulling it
     // in if it is not used (e.g., in a try/catch).
     HInstruction target = pop();
@@ skipping 20 matching lines @@
   internalError(Spannable node, String reason) {
     reporter.internalError(node, reason);
   }
 
   void generateError(ast.Node node, String message, Element helper) {
     HInstruction errorMessage = addConstantString(message);
     pushInvokeStatic(node, helper, [errorMessage]);
   }
 
   void generateRuntimeError(ast.Node node, String message) {
-    MethodElement helper = helpers.throwRuntimeError;
+    MethodElement helper = commonElements.throwRuntimeError;
     generateError(node, message, helper);
   }
 
   void generateTypeError(ast.Node node, String message) {
-    MethodElement helper = helpers.throwTypeError;
+    MethodElement helper = commonElements.throwTypeError;
     generateError(node, message, helper);
   }
 
   void generateAbstractClassInstantiationError(ast.Node node, String message) {
-    MethodElement helper = helpers.throwAbstractClassInstantiationError;
+    MethodElement helper = commonElements.throwAbstractClassInstantiationError;
     generateError(node, message, helper);
   }
 
   void generateThrowNoSuchMethod(ast.Node diagnosticNode, String methodName,
       {Link<ast.Node> argumentNodes,
       List<HInstruction> argumentValues,
       List<String> existingArguments,
       SourceInformation sourceInformation}) {
-    MethodElement helper = helpers.throwNoSuchMethod;
+    MethodElement helper = commonElements.throwNoSuchMethod;
     ConstantValue receiverConstant =
         constantSystem.createString(new ast.DartString.empty());
     HInstruction receiver = graph.addConstant(receiverConstant, closedWorld);
     ast.DartString dartString = new ast.DartString.literal(methodName);
     ConstantValue nameConstant = constantSystem.createString(dartString);
     HInstruction name = graph.addConstant(nameConstant, closedWorld);
     if (argumentValues == null) {
       argumentValues = <HInstruction>[];
       argumentNodes.forEach((argumentNode) {
         visit(argumentNode);
@@ skipping 94 matching lines @@
       List<HInstruction> arguments,
       {SourceInformation sourceInformation}) {
     // We prefer to not inline certain operations on indexables,
     // because the constant folder will handle them better and turn
     // them into simpler instructions that allow further
     // optimizations.
     bool isOptimizableOperationOnIndexable(Selector selector, Element element) {
       bool isLength = selector.isGetter && selector.name == "length";
       if (isLength || selector.isIndex) {
         return closedWorld.isSubtypeOf(
-            element.enclosingClass, helpers.jsIndexableClass);
+            element.enclosingClass, commonElements.jsIndexableClass);
       } else if (selector.isIndexSet) {
         return closedWorld.isSubtypeOf(
-            element.enclosingClass, helpers.jsMutableIndexableClass);
+            element.enclosingClass, commonElements.jsMutableIndexableClass);
       } else {
         return false;
       }
     }
 
     bool isOptimizableOperation(Selector selector, Element element) {
       ClassElement cls = element.enclosingClass;
       if (isOptimizableOperationOnIndexable(selector, element)) return true;
       if (!interceptorData.interceptedClasses.contains(cls)) return false;
       if (selector.isOperator) return true;
       if (selector.isSetter) return true;
       if (selector.isIndex) return true;
       if (selector.isIndexSet) return true;
-      if (element == helpers.jsArrayAdd ||
-          element == helpers.jsArrayRemoveLast ||
-          element == helpers.jsStringSplit) {
+      if (element == commonElements.jsArrayAdd ||
+          element == commonElements.jsArrayRemoveLast ||
+          element == commonElements.jsStringSplit) {
         return true;
       }
       return false;
     }
 
     MemberElement element = closedWorld.locateSingleElement(selector, mask);
     if (element != null &&
         !element.isField &&
         !(element.isGetter && selector.isCall) &&
         !(element.isFunction && selector.isGetter) &&
@@ skipping 95 matching lines @@
     if (type is ResolutionInterfaceType &&
         nativeData.isNativeClass(type.element)) {
       nativeBehavior.typesInstantiated.add(type);
     }
 
     // It also includes any other JS interop type if we don't trust the
     // annotation or if is declared too broad.
     if (!options.trustJSInteropTypeAnnotations ||
         type.isObject ||
         type.isDynamic) {
-      ClassElement cls = helpers.jsJavaScriptObjectClass;
+      ClassElement cls = commonElements.jsJavaScriptObjectClass;
       nativeBehavior.typesInstantiated.add(cls.thisType);
     }
 
     String code;
     if (element.isGetter) {
       code = "#";
     } else if (element.isSetter) {
       code = "# = #";
     } else {
       var args = new List.filled(arguments.length, '#').join(',');
@@ skipping 1225 matching lines @@
     }
     return new JumpHandler(this, element);
   }
 
   visitAsyncForIn(ast.AsyncForIn node) {
     // The async-for is implemented with a StreamIterator.
     HInstruction streamIterator;
 
     visit(node.expression);
     HInstruction expression = pop();
-    ConstructorElement constructor = helpers.streamIteratorConstructor;
+    ConstructorElement constructor = commonElements.streamIteratorConstructor;
     pushInvokeStatic(
         node, constructor, [expression, graph.addConstantNull(closedWorld)]);
     streamIterator = pop();
 
     void buildInitializer() {}
 
     HInstruction buildCondition() {
       Selector selector = Selectors.moveNext;
       TypeMask mask = elementInferenceResults.typeOfIteratorMoveNext(node);
       pushInvokeDynamic(node, selector, mask, [streamIterator]);
@@ skipping 47 matching lines @@
 
     // This scheme recognizes for-in on direct lists.  It does not recognize all
     // uses of ArrayIterator.  They still occur when the receiver is an Iterable
     // with a `get iterator` method that delegates to another Iterable and the
     // method is inlined.  We would require full scalar replacement in that
     // case.
 
     TypeMask mask = elementInferenceResults.typeOfIterator(node);
 
     if (mask != null &&
-        mask.satisfies(helpers.jsIndexableClass, closedWorld) &&
+        mask.satisfies(commonElements.jsIndexableClass, closedWorld) &&
         // String is indexable but not iterable.
-        !mask.satisfies(helpers.jsStringClass, closedWorld)) {
+        !mask.satisfies(commonElements.jsStringClass, closedWorld)) {
       return buildSyncForInIndexable(node, mask);
     }
     buildSyncForInIterator(node);
   }
 
   buildSyncForInIterator(ast.SyncForIn node) {
     // Generate a structure equivalent to:
     //   Iterator<E> $iter = <iterable>.iterator;
     //   while ($iter.moveNext()) {
     //     <declaredIdentifier> = $iter.current;
@@ skipping 77 matching lines @@
 
     void buildConcurrentModificationErrorCheck() {
       if (originalLength == null) return;
       // The static call checkConcurrentModificationError() is expanded in
       // codegen to:
       //
       //     array.length == _end || throwConcurrentModificationError(array)
       //
       HInstruction length = buildGetLength();
       push(new HIdentity(length, originalLength, null, boolType));
-      pushInvokeStatic(
-          node, helpers.checkConcurrentModificationError, [pop(), array]);
+      pushInvokeStatic(node, commonElements.checkConcurrentModificationError,
+          [pop(), array]);
       pop();
     }
 
     void buildInitializer() {
       visit(node.expression);
       array = pop();
       isFixed = isFixedLength(array.instructionType, closedWorld);
       localsHandler.updateLocal(
           indexVariable, graph.addConstantInt(0, closedWorld));
       originalLength = buildGetLength();
@@ skipping 107 matching lines @@
         link = link.tail) {
       visit(link.head);
       listInputs.add(pop());
       listInputs.add(pop());
     }
 
     ConstructorElement listConstructor;
     List<HInstruction> inputs = <HInstruction>[];
 
     if (listInputs.isEmpty) {
-      listConstructor = helpers.mapLiteralConstructorEmpty;
+      listConstructor = commonElements.mapLiteralConstructorEmpty;
     } else {
-      listConstructor = helpers.mapLiteralConstructor;
+      listConstructor = commonElements.mapLiteralConstructor;
       HLiteralList keyValuePairs = buildLiteralList(listInputs);
       add(keyValuePairs);
       inputs.add(keyValuePairs);
     }
 
     assert(listConstructor.isFactoryConstructor);
 
     ConstructorElement constructorElement = listConstructor;
     listConstructor = constructorElement.effectiveTarget;
 
     ResolutionInterfaceType type = elements.getType(node);
     ResolutionInterfaceType expectedType =
         constructorElement.computeEffectiveTargetType(type);
     expectedType = localsHandler.substInContext(expectedType);
 
     ClassElement cls = listConstructor.enclosingClass;
 
     MethodElement createFunction = listConstructor;
     if (rtiNeed.classNeedsRti(cls)) {
       List<HInstruction> typeInputs = <HInstruction>[];
       expectedType.typeArguments.forEach((ResolutionDartType argument) {
         typeInputs
             .add(typeBuilder.analyzeTypeArgument(argument, sourceElement));
       });
 
       // We lift this common call pattern into a helper function to save space
       // in the output.
       if (typeInputs.every((HInstruction input) => input.isNull())) {
         if (listInputs.isEmpty) {
-          createFunction = helpers.mapLiteralUntypedEmptyMaker;
+          createFunction = commonElements.mapLiteralUntypedEmptyMaker;
         } else {
-          createFunction = helpers.mapLiteralUntypedMaker;
+          createFunction = commonElements.mapLiteralUntypedMaker;
         }
       } else {
         inputs.addAll(typeInputs);
       }
     }
 
     // If rti is needed and the map literal has no type parameters,
     // 'constructor' is a static function that forwards the call to the factory
     // constructor without type parameters.
     assert(createFunction is ConstructorElement ||
         createFunction is FunctionElement);
 
     // The instruction type will always be a subtype of the mapLiteralClass, but
     // type inference might discover a more specific type, or find nothing (in
     // dart2js unit tests).
-    TypeMask mapType =
-        new TypeMask.nonNullSubtype(helpers.mapLiteralClass, closedWorld);
+    TypeMask mapType = new TypeMask.nonNullSubtype(
+        commonElements.mapLiteralClass, closedWorld);
     TypeMask returnTypeMask = TypeMaskFactory.inferredReturnTypeForElement(
         createFunction, globalInferenceResults);
     TypeMask instructionType =
         mapType.intersection(returnTypeMask, closedWorld);
 
     addInlinedInstantiation(expectedType);
     pushInvokeStatic(node, createFunction, inputs,
         typeMask: instructionType, instanceType: expectedType);
     removeInlinedInstantiation(expectedType);
   }
@@ skipping 286 matching lines @@
         // An HSwitch has n inputs and n+1 successors, the last being the
         // default case.
         expressionEnd.addSuccessor(block);
         hasDefault = true;
       }
       open(block);
       localsHandler = new LocalsHandler.from(savedLocals);
       buildSwitchCase(switchCase);
       if (!isAborted()) {
         if (caseIterator.hasNext && isReachable) {
-          pushInvokeStatic(switchCase, helpers.fallThroughError, []);
+          pushInvokeStatic(switchCase, commonElements.fallThroughError, []);
           HInstruction error = pop();
           closeAndGotoExit(new HThrow(error, error.sourceInformation));
         } else if (!isDefaultCase(switchCase)) {
           // If there is no default, we will add one later to avoid
           // the critical edge. So we generate a break statement to make
           // sure the last case does not fall through to the default case.
           jumpHandler.generateBreak();
         }
       }
       statements.add(
@@ skipping 199 matching lines @@
       startCatchBlock = graph.addNewBlock();
       open(startCatchBlock);
       // Note that the name of this local is irrelevant.
       SyntheticLocal local =
           new SyntheticLocal('exception', localsHandler.executableContext);
       exception = new HLocalValue(local, commonMasks.nonNullType);
       add(exception);
       HInstruction oldRethrowableException = rethrowableException;
       rethrowableException = exception;
 
-      pushInvokeStatic(node, helpers.exceptionUnwrapper, [exception]);
+      pushInvokeStatic(node, commonElements.exceptionUnwrapper, [exception]);
       HInvokeStatic unwrappedException = pop();
       tryInstruction.exception = exception;
       Link<ast.Node> link = node.catchBlocks.nodes;
 
       void pushCondition(ast.CatchBlock catchBlock) {
         if (catchBlock.onKeyword != null) {
           ResolutionDartType type = elements.getType(catchBlock.type);
           if (type == null) {
             reporter.internalError(catchBlock.type, 'On with no type.');
           }
@@ skipping 24 matching lines @@
       void visitThen() {
         ast.CatchBlock catchBlock = link.head;
         link = link.tail;
         if (catchBlock.exception != null) {
           LocalVariableElement exceptionVariable =
               elements[catchBlock.exception];
           localsHandler.updateLocal(exceptionVariable, unwrappedException);
         }
         ast.Node trace = catchBlock.trace;
         if (trace != null) {
-          pushInvokeStatic(trace, helpers.traceFromException, [exception]);
+          pushInvokeStatic(
+              trace, commonElements.traceFromException, [exception]);
           HInstruction traceInstruction = pop();
           LocalVariableElement traceVariable = elements[trace];
           localsHandler.updateLocal(traceVariable, traceInstruction);
         }
         visit(catchBlock);
       }
 
       void visitElse() {
         if (link.isEmpty) {
           closeAndGotoExit(new HThrow(exception, exception.sourceInformation,
@@ skipping 496 matching lines @@
       this.oldReturnLocal,
       this.oldReturnType,
       this.oldResolvedAst,
       this.oldStack,
       this.oldLocalsHandler,
       this.inTryStatement,
       this.allFunctionsCalledOnce,
       this.oldElementInferenceResults)
       : super(function);
 }