[dart2js] Remove unused 'classesOnlyNeededForRti' field.

Change-Id: I424fd9fcf6c7f8a9d0f724b5599fc96242bb9042
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/192943
Commit-Queue: Joshua Litt <joshualitt@google.com>
Reviewed-by: Mayank Patke <fishythefish@google.com>

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

@@ -261,6 +261,9 @@ class Class implements FieldContainer {
   /// Uses indicate missing information in the model.
   final ClassEntity element;
 
+  // TODO(joshualitt): Now that we collect all rti needed classes and handle
+  // them separately, we should investigate whether or not we still need to
+  // store the type data on the class.
   final ClassTypeData typeData;
 
   final js.Name name;

pkg/compiler/lib/src/js_emitter/program_builder/collector.dart

@@ -24,7 +24,6 @@ class Collector {
 
   final Set<ClassEntity> neededClasses = {};
   final Set<ClassEntity> neededClassTypes = {};
-  final Set<ClassEntity> classesOnlyNeededForRti = {};
   final Set<ClassEntity> classesOnlyNeededForConstructor = {};
   final Map<OutputUnit, List<ClassEntity>> outputClassLists = {};
   final Map<OutputUnit, List<ClassEntity>> outputClassTypeLists = {};
@@ -140,17 +139,6 @@ class Collector {
     Set<ClassEntity> backendTypeHelpers =
         getBackendTypeHelpers(_commonElements).toSet();
 
-    /// A class type is 'shadowed' if the class is needed for direct
-    /// instantiation in one OutputUnit while its type is needed in another
-    /// OutputUnit.
-    bool isClassTypeShadowed(ClassEntity cls) {
-      return !backendTypeHelpers.contains(cls) &&
-          _rtiNeededClasses.contains(cls) &&
-          !classesOnlyNeededForRti.contains(cls) &&
-          _outputUnitData.outputUnitForClass(cls) !=
-              _outputUnitData.outputUnitForClassType(cls);
-    }
-
     // Compute needed classes.
     Set<ClassEntity> instantiatedClasses =
         // TODO(johnniwinther): This should be accessed from a codegen closed
@@ -184,20 +172,10 @@ class Collector {
       }
     }
 
-    // 4. Find all classes needed for rti.
-    // It is important that this is the penultimate step, at this point,
-    // neededClasses must only contain classes that have been resolved and
-    // codegen'd. The rtiNeededClasses may contain additional classes, but
-    // these are thought to not have been instantiated, so we need to be able
-    // to identify them later and make sure we only emit "empty shells" without
-    // fields, etc.
+    // 4. Find all class types needed for rti.
     for (ClassEntity cls in _rtiNeededClasses) {
       if (backendTypeHelpers.contains(cls)) continue;
-      while (cls != null && !neededClasses.contains(cls)) {
-        if (!classesOnlyNeededForRti.add(cls)) break;
-        // TODO(joshualitt) delete classesOnlyNeededForRti when the
-        // no-defer-class_types flag is removed.
-        neededClassTypes.add(cls);
+      while (cls != null && neededClassTypes.add(cls)) {
         cls = _elementEnvironment.getSuperClass(cls);
       }
     }
@@ -219,14 +197,7 @@ class Collector {
       }
     }
 
-    // 6. Collect any class types 'shadowed' by direct instantiation.
-    for (ClassEntity cls in _rtiNeededClasses) {
-      if (isClassTypeShadowed(cls)) {
-        neededClassTypes.add(cls);
-      }
-    }
-
-    // 7. Sort classes needed for type checking and then add them to their
+    // 6. Sort classes needed for type checking and then add them to their
     // respective OutputUnits.
     for (ClassEntity cls in _sorter.sortClasses(neededClassTypes)) {
       outputClassTypeLists

pkg/compiler/test/deferred_loading/data/shadowed_types/lib_shared.dart

@@ -0,0 +1,45 @@
+// Copyright (c) 2021, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/*class: A:
+ class_unit=1{libb},
+ type_unit=2{libb, liba}
+*/
+/*member: A.:member_unit=1{libb}*/
+class A {}
+
+/*class: B:
+ class_unit=main{},
+ type_unit=main{}
+*/
+/*member: B.:member_unit=main{}*/
+class B {}
+
+/*class: C_Parent:
+ class_unit=1{libb},
+ type_unit=main{}
+*/
+/*member: C_Parent.:member_unit=1{libb}*/
+class C_Parent {}
+
+/*class: D:
+ class_unit=1{libb},
+ type_unit=2{libb, liba}
+*/
+/*member: D.:member_unit=1{libb}*/
+class D {}
+
+/*class: E:
+ class_unit=1{libb},
+ type_unit=1{libb}
+*/
+/*member: E.:member_unit=1{libb}*/
+class E extends D {}
+
+/*class: F:
+ class_unit=1{libb},
+ type_unit=1{libb}
+*/
+/*member: F.:member_unit=1{libb}*/
+class F {}

pkg/compiler/test/deferred_loading/data/shadowed_types/liba.dart

@@ -0,0 +1,17 @@
+// Copyright (c) 2021, 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 'lib_shared.dart';
+
+@pragma('dart2js:noInline')
+/*member: isA:member_unit=3{liba}*/
+isA(foo) {
+  return foo is A;
+}
+
+@pragma('dart2js:noInline')
+/*member: isD:member_unit=3{liba}*/
+isD(foo) {
+  return foo is D;
+}

pkg/compiler/test/deferred_loading/data/shadowed_types/libb.dart

@@ -0,0 +1,43 @@
+// Copyright (c) 2021, 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 'lib_shared.dart';
+
+@pragma('dart2js:noInline')
+/*member: createA:member_unit=1{libb}*/
+createA() {
+  return A();
+}
+
+@pragma('dart2js:noInline')
+/*member: isB:member_unit=1{libb}*/
+isB(foo) {
+  return foo is B;
+}
+
+/*class: C:
+ class_unit=1{libb},
+ type_unit=main{}
+*/
+/*member: C.:member_unit=1{libb}*/
+class C extends C_Parent {}
+
+@pragma('dart2js:noInline')
+/*member: createC:member_unit=1{libb}*/
+createC() {
+  return C();
+}
+
+@pragma('dart2js:noInline')
+/*member: createE:member_unit=1{libb}*/
+createE() {
+  return E();
+}
+
+@pragma('dart2js:noInline')
+/*member: isFWithUnused:member_unit=1{libb}*/
+isFWithUnused(foo) {
+  var unused = F();
+  return foo is F;
+}

pkg/compiler/test/deferred_loading/data/shadowed_types/main.dart

@@ -0,0 +1,31 @@
+// Copyright (c) 2021, 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.
+
+/*library: 
+ output_units=[
+  f1: {units: [3{liba}], usedBy: [], needs: []},
+  f2: {units: [1{libb}], usedBy: [], needs: []}],
+ steps=[
+  liba=(f1),
+  libb=(f2)]
+*/
+
+import 'liba.dart' deferred as liba;
+import 'libb.dart' deferred as libb;
+import 'lib_shared.dart';
+
+/*member: main:member_unit=main{}*/
+main() async {
+  var f = /*closure_unit=main{}*/ () => libb.C();
+  print(f is C_Parent Function());
+  await liba.loadLibrary();
+  await libb.loadLibrary();
+
+  print(liba.isA(libb.createA()));
+  print(libb.createA());
+  print(libb.createC());
+  print(libb.isB(B()));
+  print(liba.isD(libb.createE()));
+  print(libb.isFWithUnused(null as dynamic));
+}

tests/web/deferred/shadowed_types/lib_shared.dart

@@ -0,0 +1,22 @@
+// Copyright (c) 2021, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Class A has a type used in libb, but a class used in liba.
+class A {}
+
+// Class B has a class used in the main output unit, and a type used in libb.
+class B {}
+
+// Class C_Parent is extended is libb, and closed around in the main output
+// unit.
+class C_Parent {}
+
+// Classes D through F represent a simple heirarchy.
+// D's type is used in liba.
+// F is instantiated, but unused in libb.
+class D {}
+
+class E extends D {}
+
+class F {}

tests/web/deferred/shadowed_types/liba.dart

@@ -0,0 +1,15 @@
+// Copyright (c) 2021, 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 'lib_shared.dart';
+
+@pragma('dart2js:noInline')
+isA(foo) {
+  return foo is A;
+}
+
+@pragma('dart2js:noInline')
+isD(foo) {
+  return foo is D;
+}

tests/web/deferred/shadowed_types/libb.dart

@@ -0,0 +1,33 @@
+// Copyright (c) 2021, 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 'lib_shared.dart';
+
+@pragma('dart2js:noInline')
+createA() {
+  return A();
+}
+
+@pragma('dart2js:noInline')
+isB(foo) {
+  return foo is B;
+}
+
+class C extends C_Parent {}
+
+@pragma('dart2js:noInline')
+createC() {
+  return C();
+}
+
+@pragma('dart2js:noInline')
+createE() {
+  return E();
+}
+
+@pragma('dart2js:noInline')
+isFWithUnused(foo) {
+  var unused = F();
+  return foo is F;
+}

tests/web/deferred/shadowed_types/shadowed_types_test.dart

@@ -0,0 +1,22 @@
+// Copyright (c) 2021, 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 'package:expect/expect.dart';
+import 'liba.dart' deferred as liba;
+import 'libb.dart' deferred as libb;
+import 'lib_shared.dart';
+
+main() async {
+  var f = () => libb.C();
+  Expect.isTrue(f is C_Parent Function());
+  await liba.loadLibrary();
+  await libb.loadLibrary();
+
+  Expect.isTrue(liba.isA(libb.createA()));
+  print(libb.createA());
+  print(libb.createC());
+  Expect.isTrue(libb.isB(B()));
+  Expect.isTrue(liba.isD(libb.createE()));
+  Expect.isFalse(libb.isFWithUnused(null as dynamic));
+}