Extract BackendUsage, MirrorsData, and CheckedModeHelpers from Backend.

pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart

Index: pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart
diff --git a/pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart b/pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart
index 044cdd5b5ba32691266879e3d6888886f7426b95..ab44766eea8b877bb925bed00bd66f5f0e6e846d 100644
--- a/pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart
+++ b/pkg/compiler/lib/src/js_backend/checked_mode_helpers.dart
@@ -2,36 +2,37 @@
 // 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 '../compiler.dart' show Compiler;
-import '../elements/resolution_types.dart';
-import '../elements/elements.dart';
+import '../common.dart';
+import '../core_types.dart';
+import '../elements/elements.dart' show ErroneousElement;
+import '../elements/entities.dart';
+import '../elements/resolution_types.dart' show MalformedType;
+import '../elements/types.dart';
 import '../js/js.dart' as jsAst;
 import '../js/js.dart' show js;
 import '../ssa/codegen.dart' show SsaCodeGenerator;
 import '../ssa/nodes.dart' show HTypeConversion;
 import '../universe/call_structure.dart' show CallStructure;
 import '../universe/use.dart' show StaticUse;
-import 'backend.dart';
+import 'backend_helpers.dart';
 
 class CheckedModeHelper {
   final String name;
 
   const CheckedModeHelper(String this.name);
 
-  StaticUse getStaticUse(Compiler compiler) {
-    JavaScriptBackend backend = compiler.backend;
+  StaticUse getStaticUse(BackendHelpers helpers) {
     // TODO(johnniwinther): Refactor this to avoid looking up directly in the
     // js helper library but instead access helpers directly on backend helpers.
-    LibraryElement jsHelperLibrary = backend.helpers.jsHelperLibrary;
-    MethodElement method = jsHelperLibrary.find(name);
-    return new StaticUse.staticInvoke(method, callStructure);
+    return new StaticUse.staticInvoke(
+        helpers.findHelperFunction(name), callStructure);
   }
 
   CallStructure get callStructure => CallStructure.ONE_ARG;
 
   jsAst.Expression generateCall(
       SsaCodeGenerator codegen, HTypeConversion node) {
-    StaticUse staticUse = getStaticUse(codegen.compiler);
+    StaticUse staticUse = getStaticUse(codegen.backend.helpers);
     codegen.registry.registerStaticUse(staticUse);
     List<jsAst.Expression> arguments = <jsAst.Expression>[];
     codegen.use(node.checkedInput);
@@ -46,43 +47,6 @@ class CheckedModeHelper {
       HTypeConversion node, List<jsAst.Expression> arguments) {
     // No additional arguments needed.
   }
-
-  static const List<CheckedModeHelper> helpers = const <CheckedModeHelper>[
-    const MalformedCheckedModeHelper('checkMalformedType'),
-    const CheckedModeHelper('voidTypeCheck'),
-    const CheckedModeHelper('stringTypeCast'),
-    const CheckedModeHelper('stringTypeCheck'),
-    const CheckedModeHelper('doubleTypeCast'),
-    const CheckedModeHelper('doubleTypeCheck'),
-    const CheckedModeHelper('numTypeCast'),
-    const CheckedModeHelper('numTypeCheck'),
-    const CheckedModeHelper('boolTypeCast'),
-    const CheckedModeHelper('boolTypeCheck'),
-    const CheckedModeHelper('intTypeCast'),
-    const CheckedModeHelper('intTypeCheck'),
-    const PropertyCheckedModeHelper('numberOrStringSuperNativeTypeCast'),
-    const PropertyCheckedModeHelper('numberOrStringSuperNativeTypeCheck'),
-    const PropertyCheckedModeHelper('numberOrStringSuperTypeCast'),
-    const PropertyCheckedModeHelper('numberOrStringSuperTypeCheck'),
-    const PropertyCheckedModeHelper('stringSuperNativeTypeCast'),
-    const PropertyCheckedModeHelper('stringSuperNativeTypeCheck'),
-    const PropertyCheckedModeHelper('stringSuperTypeCast'),
-    const PropertyCheckedModeHelper('stringSuperTypeCheck'),
-    const CheckedModeHelper('listTypeCast'),
-    const CheckedModeHelper('listTypeCheck'),
-    const PropertyCheckedModeHelper('listSuperNativeTypeCast'),
-    const PropertyCheckedModeHelper('listSuperNativeTypeCheck'),
-    const PropertyCheckedModeHelper('listSuperTypeCast'),
-    const PropertyCheckedModeHelper('listSuperTypeCheck'),
-    const PropertyCheckedModeHelper('interceptedTypeCast'),
-    const PropertyCheckedModeHelper('interceptedTypeCheck'),
-    const SubtypeCheckedModeHelper('subtypeCast'),
-    const SubtypeCheckedModeHelper('assertSubtype'),
-    const TypeVariableCheckedModeHelper('subtypeOfRuntimeTypeCast'),
-    const TypeVariableCheckedModeHelper('assertSubtypeOfRuntimeType'),
-    const PropertyCheckedModeHelper('propertyTypeCast'),
-    const PropertyCheckedModeHelper('propertyTypeCheck')
-  ];
 }
 
 class MalformedCheckedModeHelper extends CheckedModeHelper {
@@ -92,6 +56,7 @@ class MalformedCheckedModeHelper extends CheckedModeHelper {
 
   void generateAdditionalArguments(SsaCodeGenerator codegen,
       HTypeConversion node, List<jsAst.Expression> arguments) {
+    // TODO(johnniwinther): Support malformed types in [types.dart].
     MalformedType type = node.typeExpression;
     ErroneousElement element = type.element;
     arguments.add(js.escapedString(element.message));
@@ -105,7 +70,7 @@ class PropertyCheckedModeHelper extends CheckedModeHelper {
 
   void generateAdditionalArguments(SsaCodeGenerator codegen,
       HTypeConversion node, List<jsAst.Expression> arguments) {
-    ResolutionDartType type = node.typeExpression;
+    DartType type = node.typeExpression;
     jsAst.Name additionalArgument = codegen.backend.namer.operatorIsType(type);
     arguments.add(js.quoteName(additionalArgument));
   }
@@ -131,8 +96,8 @@ class SubtypeCheckedModeHelper extends CheckedModeHelper {
 
   void generateAdditionalArguments(SsaCodeGenerator codegen,
       HTypeConversion node, List<jsAst.Expression> arguments) {
-    ResolutionDartType type = node.typeExpression;
-    Element element = type.element;
+    InterfaceType type = node.typeExpression;
+    ClassEntity element = type.element;
     jsAst.Name isField = codegen.backend.namer.operatorIs(element);
     arguments.add(js.quoteName(isField));
     codegen.use(node.typeRepresentation);
@@ -141,3 +106,189 @@ class SubtypeCheckedModeHelper extends CheckedModeHelper {
     arguments.add(js.quoteName(asField));
   }
 }
+
+class CheckedModeHelpers {
+  final CommonElements _commonElements;
+  final BackendHelpers _helpers;
+
+  CheckedModeHelpers(this._commonElements, this._helpers);
+
+  /// All the checked mode helpers.
+  static const List<CheckedModeHelper> helpers = const <CheckedModeHelper>[
+    const MalformedCheckedModeHelper('checkMalformedType'),
+    const CheckedModeHelper('voidTypeCheck'),
+    const CheckedModeHelper('stringTypeCast'),
+    const CheckedModeHelper('stringTypeCheck'),
+    const CheckedModeHelper('doubleTypeCast'),
+    const CheckedModeHelper('doubleTypeCheck'),
+    const CheckedModeHelper('numTypeCast'),
+    const CheckedModeHelper('numTypeCheck'),
+    const CheckedModeHelper('boolTypeCast'),
+    const CheckedModeHelper('boolTypeCheck'),
+    const CheckedModeHelper('intTypeCast'),
+    const CheckedModeHelper('intTypeCheck'),
+    const PropertyCheckedModeHelper('numberOrStringSuperNativeTypeCast'),
+    const PropertyCheckedModeHelper('numberOrStringSuperNativeTypeCheck'),
+    const PropertyCheckedModeHelper('numberOrStringSuperTypeCast'),
+    const PropertyCheckedModeHelper('numberOrStringSuperTypeCheck'),
+    const PropertyCheckedModeHelper('stringSuperNativeTypeCast'),
+    const PropertyCheckedModeHelper('stringSuperNativeTypeCheck'),
+    const PropertyCheckedModeHelper('stringSuperTypeCast'),
+    const PropertyCheckedModeHelper('stringSuperTypeCheck'),
+    const CheckedModeHelper('listTypeCast'),
+    const CheckedModeHelper('listTypeCheck'),
+    const PropertyCheckedModeHelper('listSuperNativeTypeCast'),
+    const PropertyCheckedModeHelper('listSuperNativeTypeCheck'),
+    const PropertyCheckedModeHelper('listSuperTypeCast'),
+    const PropertyCheckedModeHelper('listSuperTypeCheck'),
+    const PropertyCheckedModeHelper('interceptedTypeCast'),
+    const PropertyCheckedModeHelper('interceptedTypeCheck'),
+    const SubtypeCheckedModeHelper('subtypeCast'),
+    const SubtypeCheckedModeHelper('assertSubtype'),
+    const TypeVariableCheckedModeHelper('subtypeOfRuntimeTypeCast'),
+    const TypeVariableCheckedModeHelper('assertSubtypeOfRuntimeType'),
+    const PropertyCheckedModeHelper('propertyTypeCast'),
+    const PropertyCheckedModeHelper('propertyTypeCheck'),
+  ];
+
+  // Checked mode helpers indexed by name.
+  static final Map<String, CheckedModeHelper> checkedModeHelperByName =
+      new Map<String, CheckedModeHelper>.fromIterable(helpers,
+          key: (helper) => helper.name);
+
+  /**
+   * Returns the checked mode helper that will be needed to do a type check/type
+   * cast on [type] at runtime. Note that this method is being called both by
+   * the resolver with interface types (int, String, ...), and by the SSA
+   * backend with implementation types (JSInt, JSString, ...).
+   */
+  CheckedModeHelper getCheckedModeHelper(DartType type, {bool typeCast}) {
+    return getCheckedModeHelperInternal(type,
+        typeCast: typeCast, nativeCheckOnly: false);
+  }
+
+  /**
+   * Returns the native checked mode helper that will be needed to do a type
+   * check/type cast on [type] at runtime. If no native helper exists for
+   * [type], [:null:] is returned.
+   */
+  CheckedModeHelper getNativeCheckedModeHelper(DartType type, {bool typeCast}) {
+    return getCheckedModeHelperInternal(type,
+        typeCast: typeCast, nativeCheckOnly: true);
+  }
+
+  /**
+   * Returns the checked mode helper for the type check/type cast for [type]. If
+   * [nativeCheckOnly] is [:true:], only names for native helpers are returned.
+   */
+  CheckedModeHelper getCheckedModeHelperInternal(DartType type,
+      {bool typeCast, bool nativeCheckOnly}) {
+    String name = getCheckedModeHelperNameInternal(type,
+        typeCast: typeCast, nativeCheckOnly: nativeCheckOnly);
+    if (name == null) return null;
+    CheckedModeHelper helper = checkedModeHelperByName[name];
+    assert(helper != null);
+    return helper;
+  }
+
+  String getCheckedModeHelperNameInternal(DartType type,
+      {bool typeCast, bool nativeCheckOnly}) {
+    assert(!type.isTypedef);
+    if (type.isMalformed) {
+      // The same error is thrown for type test and type cast of a malformed
+      // type so we only need one check method.
+      return 'checkMalformedType';
+    }
+
+    if (type.isVoid) {
+      assert(!typeCast); // Cannot cast to void.
+      if (nativeCheckOnly) return null;
+      return 'voidTypeCheck';
+    }
+
+    if (type.isTypeVariable) {
+      return typeCast
+          ? 'subtypeOfRuntimeTypeCast'
+          : 'assertSubtypeOfRuntimeType';
+    }
+
+    if (type.isFunctionType) return null;
+
+    assert(invariant(NO_LOCATION_SPANNABLE, type.isInterfaceType,
+        message: "Unexpected type: $type"));
+    InterfaceType interfaceType = type;
+    ClassEntity element = interfaceType.element;
+    bool nativeCheck = true;
+    // TODO(13955), TODO(9731).  The test for non-primitive types should use an
+    // interceptor.  The interceptor should be an argument to HTypeConversion so
+    // that it can be optimized by standard interceptor optimizations.
+    //  nativeCheckOnly || emitter.nativeEmitter.requiresNativeIsCheck(element);
+
+    var suffix = typeCast ? 'TypeCast' : 'TypeCheck';
+    if (element == _helpers.jsStringClass ||
+        element == _commonElements.stringClass) {
+      if (nativeCheckOnly) return null;
+      return 'string$suffix';
+    }
+
+    if (element == _helpers.jsDoubleClass ||
+        element == _commonElements.doubleClass) {
+      if (nativeCheckOnly) return null;
+      return 'double$suffix';
+    }
+
+    if (element == _helpers.jsNumberClass ||
+        element == _commonElements.numClass) {
+      if (nativeCheckOnly) return null;
+      return 'num$suffix';
+    }
+
+    if (element == _helpers.jsBoolClass ||
+        element == _commonElements.boolClass) {
+      if (nativeCheckOnly) return null;
+      return 'bool$suffix';
+    }
+
+    if (element == _helpers.jsIntClass ||
+        element == _commonElements.intClass ||
+        element == _helpers.jsUInt32Class ||
+        element == _helpers.jsUInt31Class ||
+        element == _helpers.jsPositiveIntClass) {
+      if (nativeCheckOnly) return null;
+      return 'int$suffix';
+    }
+
+    if (_commonElements.isNumberOrStringSupertype(element)) {
+      return nativeCheck
+          ? 'numberOrStringSuperNative$suffix'
+          : 'numberOrStringSuper$suffix';
+    }
+
+    if (_commonElements.isStringOnlySupertype(element)) {
+      return nativeCheck ? 'stringSuperNative$suffix' : 'stringSuper$suffix';
+    }
+
+    if ((element == _commonElements.listClass ||
+            element == _helpers.jsArrayClass) &&
+        type.treatAsRaw) {
+      if (nativeCheckOnly) return null;
+      return 'list$suffix';
+    }
+
+    if (_commonElements.isListSupertype(element)) {
+      return nativeCheck ? 'listSuperNative$suffix' : 'listSuper$suffix';
+    }
+
+    if (type.isInterfaceType && !type.treatAsRaw) {
+      return typeCast ? 'subtypeCast' : 'assertSubtype';
+    }
+
+    if (nativeCheck) {
+      // TODO(karlklose): can we get rid of this branch when we use
+      // interceptors?
+      return 'intercepted$suffix';
+    } else {
+      return 'property$suffix';
+    }
+  }
+}