[dart2js] Add redirections for unneeded native classes in ruleset.

Change-Id: Ic29686447c87b7707480a161e76ab500c1455617
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/130011
Commit-Queue: Mayank Patke <fishythefish@google.com>
Reviewed-by: Sigmund Cherem <sigmund@google.com>

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

@@ -501,8 +501,8 @@ class Ruleset {
   bool get isEmpty => _redirections.isEmpty && _entries.isEmpty;
   bool get isNotEmpty => _redirections.isNotEmpty || _entries.isNotEmpty;
 
-  void addRedirection(ClassEntity targetClass, ClassEntity redirection) {
-    _redirections[targetClass] = redirection;
+  void addRedirection(ClassEntity redirectee, ClassEntity target) {
+    _redirections[redirectee] = target;
   }
 
   void addEntry(InterfaceType targetType, Iterable<InterfaceType> supertypes,

pkg/compiler/lib/src/js_emitter/code_emitter_task.dart

@@ -94,6 +94,7 @@ class CodeEmitterTask extends CompilerTask {
           closedWorld,
           codegen.rtiEncoder,
           codegen.rtiRecipeEncoder,
+          _nativeEmitter,
           _backendStrategy.sourceInformationStrategy,
           this,
           _generateSourceMap);

pkg/compiler/lib/src/js_emitter/model.dart

@@ -4,6 +4,7 @@
 
 library dart2js.new_js_emitter.model;
 
+import '../common_elements.dart';
 import '../constants/values.dart' show ConstantValue;
 import '../deferred_load.dart' show OutputUnit;
 import '../elements/entities.dart';
@@ -315,6 +316,10 @@ class Class implements FieldContainer {
 
   bool get isSimpleMixinApplication => false;
 
+  bool isTriviallyChecked(CommonElements commonElements) =>
+      classChecksNewRti.checks.every((TypeCheck check) =>
+          check.cls == commonElements.objectClass || check.cls == element);
+
   Class get superclass => _superclass;
 
   void setSuperclass(Class superclass) {

pkg/compiler/lib/src/js_emitter/native_emitter.dart

@@ -37,6 +37,10 @@ class NativeEmitter {
   // Caches the methods that have a native body.
   Set<FunctionEntity> nativeMethods = new Set<FunctionEntity>();
 
+  // Type metadata redirections, where the key is the class being redirected to
+  // and the value is the list of classes being redirected.
+  final Map<Class, List<Class>> typeRedirections = {};
+
   NativeEmitter(
       this._emitterTask, this._closedWorld, this._nativeCodegenEnqueuer);
 
@@ -112,6 +116,7 @@ class NativeEmitter {
     // Find which classes are needed and which are non-leaf classes.  Any class
     // that is not needed can be treated as a leaf class equivalent to some
     // needed class.
+    // We may still need to include type metadata for some unneeded classes.
 
     Set<Class> neededClasses = new Set<Class>();
     Set<Class> nonLeafClasses = new Set<Class>();
@@ -152,6 +157,19 @@ class NativeEmitter {
         neededClasses.add(cls);
         neededClasses.add(cls.superclass);
         nonLeafClasses.add(cls.superclass);
+      } else if (!cls.isTriviallyChecked(_commonElements) ||
+          cls.namedTypeVariablesNewRti.isNotEmpty) {
+        // The class is not marked 'needed', but we still need it in the type
+        // metadata.
+
+        // Redirect this class (and all classes which would have redirected to
+        // this class) to its superclass. Because we have a post-order visit,
+        // this eventually causes all such native classes to redirect to their
+        // leaf interceptors.
+        List<Class> redirectedClasses = typeRedirections[cls] ?? [];
+        redirectedClasses.add(cls);
+        typeRedirections[cls.superclass] = redirectedClasses;
+        typeRedirections.remove(cls);
       }
     }
 

pkg/compiler/lib/src/js_emitter/startup_emitter/emitter.dart

@@ -23,6 +23,7 @@ import '../../universe/codegen_world_builder.dart' show CodegenWorld;
 import '../../world.dart' show JClosedWorld;
 import '../js_emitter.dart' show Emitter, ModularEmitter;
 import '../model.dart';
+import '../native_emitter.dart';
 import '../program_builder/program_builder.dart' show ProgramBuilder;
 import 'model_emitter.dart';
 
@@ -152,6 +153,7 @@ class EmitterImpl extends ModularEmitterBase implements Emitter {
   final RecipeEncoder _rtiRecipeEncoder;
   final CompilerTask _task;
   ModelEmitter _emitter;
+  final NativeEmitter _nativeEmitter;
 
   @override
   Program programForTesting;
@@ -165,6 +167,7 @@ class EmitterImpl extends ModularEmitterBase implements Emitter {
       this._closedWorld,
       this._rtiEncoder,
       this._rtiRecipeEncoder,
+      this._nativeEmitter,
       SourceInformationStrategy sourceInformationStrategy,
       this._task,
       bool shouldGenerateSourceMap)
@@ -178,6 +181,7 @@ class EmitterImpl extends ModularEmitterBase implements Emitter {
         _closedWorld,
         _task,
         this,
+        _nativeEmitter,
         sourceInformationStrategy,
         _rtiEncoder,
         _rtiRecipeEncoder,

pkg/compiler/lib/src/js_emitter/startup_emitter/fragment_emitter.dart

@@ -594,6 +594,7 @@ class FragmentEmitter {
   final Emitter _emitter;
   final ConstantEmitter _constantEmitter;
   final ModelEmitter _modelEmitter;
+  final NativeEmitter _nativeEmitter;
   final JClosedWorld _closedWorld;
   final CodegenWorld _codegenWorld;
   RecipeEncoder _recipeEncoder;
@@ -622,6 +623,7 @@ class FragmentEmitter {
       this._emitter,
       this._constantEmitter,
       this._modelEmitter,
+      this._nativeEmitter,
       this._closedWorld,
       this._codegenWorld) {
     if (_options.experimentNewRti) {
@@ -1977,6 +1979,9 @@ class FragmentEmitter {
     ClassEntity jsObjectClass = _commonElements.jsJavaScriptObjectClass;
     InterfaceType jsObjectType = _elementEnvironment.getThisType(jsObjectClass);
 
+    Map<Class, List<Class>> nativeRedirections =
+        _nativeEmitter.typeRedirections;
+
     Ruleset ruleset = Ruleset.empty();
     Map<ClassEntity, int> erasedTypes = {};
     Iterable<Class> classes =
@@ -1990,17 +1995,20 @@ class FragmentEmitter {
         erasedTypes[element] = targetType.typeArguments.length;
       }
 
-      if (cls.classChecksNewRti == null) return;
       bool isInterop = _nativeData.isJsInteropClass(element);
 
-      Iterable<TypeCheck> checks = cls.classChecksNewRti.checks;
+      Iterable<TypeCheck> checks = cls.classChecksNewRti?.checks ?? [];
       Iterable<InterfaceType> supertypes = isInterop
           ? checks
               .map((check) => _elementEnvironment.getJsInteropType(check.cls))
           : checks
               .map((check) => _dartTypes.asInstanceOf(targetType, check.cls));
 
       Map<TypeVariableType, DartType> typeVariables = {};
+      Set<TypeVariableType> namedTypeVariables = cls.namedTypeVariablesNewRti;
+      nativeRedirections[cls]?.forEach((Class redirectee) {
+        namedTypeVariables.addAll(redirectee.namedTypeVariablesNewRti);
+      });
       for (TypeVariableType typeVariable in cls.namedTypeVariablesNewRti) {
         TypeVariableEntity element = typeVariable.element;
         InterfaceType supertype = isInterop
@@ -2026,6 +2034,12 @@ class FragmentEmitter {
       });
     }
 
+    nativeRedirections.forEach((Class target, List<Class> redirectees) {
+      for (Class redirectee in redirectees) {
+        ruleset.addRedirection(redirectee.element, target.element);
+      }
+    });
+
     if (ruleset.isNotEmpty) {
       FunctionEntity addRules = _closedWorld.commonElements.rtiAddRulesMethod;
       statements.add(js.js.statement('#(init.#,JSON.parse(#));', [

pkg/compiler/lib/src/js_emitter/startup_emitter/model_emitter.dart

@@ -69,6 +69,7 @@ import '../constant_ordering.dart' show ConstantOrdering;
 import '../headers.dart';
 import '../js_emitter.dart' show buildTearOffCode, NativeGenerator;
 import '../model.dart';
+import '../native_emitter.dart';
 
 part 'fragment_emitter.dart';
 
@@ -81,6 +82,7 @@ class ModelEmitter {
   final CompilerTask _task;
   final Emitter _emitter;
   ConstantEmitter _constantEmitter;
+  final NativeEmitter _nativeEmitter;
   final bool _shouldGenerateSourceMap;
   final JClosedWorld _closedWorld;
   final ConstantOrdering _constantOrdering;
@@ -109,6 +111,7 @@ class ModelEmitter {
       this._closedWorld,
       this._task,
       this._emitter,
+      this._nativeEmitter,
       this._sourceInformationStrategy,
       RuntimeTypesEncoder rtiEncoder,
       RecipeEncoder rtiRecipeEncoder,
@@ -189,6 +192,7 @@ class ModelEmitter {
         _emitter,
         _constantEmitter,
         this,
+        _nativeEmitter,
         _closedWorld,
         codegenWorld);