(dart2js) release some data-structures after resolution.

The resolution-world-builder and impact transformer were holding onto a
class-hierarchy-builder in dart2js, which uses a lot of space.

On a some artificial sample apps with thousands of classes this
reduces the overall memory capacity by 25%. On a large internal app
this reduced the overall memory capacity from 13G to 11G.

Change-Id: I5d0d40764649364f2cd2411ef1346812beb411c4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/129544
Commit-Queue: Sigmund Cherem <sigmund@google.com>
Reviewed-by: Stephen Adams <sra@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>

pkg/compiler/lib/src/compiler.dart

@@ -184,8 +184,10 @@ abstract class Compiler {
     return new JsBackendStrategy(this);
   }
 
-  ResolutionWorldBuilder get resolutionWorldBuilder =>
-      enqueuer.resolution.worldBuilder;
+  ResolutionWorldBuilder resolutionWorldBuilderForTesting;
+
+  KClosedWorld get frontendClosedWorldForTesting =>
+      resolutionWorldBuilderForTesting.closedWorldForTesting;
 
   CodegenWorldBuilder get codegenWorldBuilder {
     assert(
@@ -301,24 +303,12 @@ abstract class Compiler {
     }
   }
 
-  /// Starts the resolution phase, creating the [ResolutionEnqueuer] if not
-  /// already created.
-  ///
-  /// During normal compilation resolution only started once, but through
-  /// [analyzeUri] resolution is started repeatedly.
-  ResolutionEnqueuer startResolution() {
-    ResolutionEnqueuer resolutionEnqueuer;
-    if (enqueuer.hasResolution) {
-      resolutionEnqueuer = enqueuer.resolution;
-    } else {
-      resolutionEnqueuer = enqueuer.createResolutionEnqueuer();
-      frontendStrategy.onResolutionStart();
-    }
-    return resolutionEnqueuer;
-  }
-
   JClosedWorld computeClosedWorld(Uri rootLibraryUri, Iterable<Uri> libraries) {
-    ResolutionEnqueuer resolutionEnqueuer = startResolution();
+    ResolutionEnqueuer resolutionEnqueuer = enqueuer.createResolutionEnqueuer();
+    if (retainDataForTesting) {
+      resolutionWorldBuilderForTesting = resolutionEnqueuer.worldBuilder;
+    }
+    frontendStrategy.onResolutionStart();
     for (LibraryEntity library
         in frontendStrategy.elementEnvironment.libraries) {
       frontendStrategy.elementEnvironment.forEachClass(library,
@@ -361,7 +351,8 @@ abstract class Compiler {
     assert(mainFunction != null);
     checkQueue(resolutionEnqueuer);
 
-    JClosedWorld closedWorld = closeResolution(mainFunction);
+    JClosedWorld closedWorld =
+        closeResolution(mainFunction, resolutionEnqueuer.worldBuilder);
     if (retainDataForTesting) {
       backendClosedWorldForTesting = closedWorld;
     }
@@ -444,7 +435,8 @@ abstract class Compiler {
   }
 
   /// Perform the steps needed to fully end the resolution phase.
-  JClosedWorld closeResolution(FunctionEntity mainFunction) {
+  JClosedWorld closeResolution(FunctionEntity mainFunction,
+      ResolutionWorldBuilder resolutionWorldBuilder) {
     phase = PHASE_DONE_RESOLVING;
 
     KClosedWorld kClosedWorld = resolutionWorldBuilder.closeWorld(reporter);

pkg/compiler/lib/src/deferred_load.dart

@@ -184,7 +184,7 @@ abstract class DeferredLoadTask extends CompilerTask {
       MemberEntity element, Dependencies dependencies) {
     // TODO(sigurdm): We want to be more specific about this - need a better
     // way to query "liveness".
-    if (!compiler.resolutionWorldBuilder.isMemberUsed(element)) {
+    if (!closedWorld.isMemberUsed(element)) {
       return;
     }
     _collectDependenciesFromImpact(closedWorld, element, dependencies);
@@ -203,7 +203,7 @@ abstract class DeferredLoadTask extends CompilerTask {
     // to.  Static members are not relevant, unless we are processing
     // extra dependencies due to mirrors.
     void addLiveInstanceMember(MemberEntity member) {
-      if (!compiler.resolutionWorldBuilder.isMemberUsed(member)) return;
+      if (!closedWorld.isMemberUsed(member)) return;
       if (!member.isInstanceMember) return;
       dependencies.addMember(member);
       _collectDirectMemberDependencies(closedWorld, member, dependencies);

pkg/compiler/lib/src/enqueue.dart

@@ -37,7 +37,8 @@ import 'util/util.dart' show Setlet;
 import 'world.dart' show JClosedWorld;
 
 class EnqueueTask extends CompilerTask {
-  ResolutionEnqueuer _resolution;
+  ResolutionEnqueuer resolutionEnqueuerForTesting;
+  bool _resolutionEnqueuerCreated = false;
   CodegenEnqueuer codegenEnqueuerForTesting;
   final Compiler compiler;
 
@@ -48,22 +49,16 @@ class EnqueueTask extends CompilerTask {
       : this.compiler = compiler,
         super(compiler.measurer);
 
-  // TODO(johnniwinther): Remove the need for this.
-  bool get hasResolution => _resolution != null;
-
-  // TODO(johnniwinther): Remove the need for this.
-  ResolutionEnqueuer get resolution {
-    assert(
-        _resolution != null,
-        failedAt(NO_LOCATION_SPANNABLE,
-            "ResolutionEnqueuer has not been created yet."));
-    return _resolution;
-  }
-
   ResolutionEnqueuer createResolutionEnqueuer() {
-    return _resolution ??= compiler.frontendStrategy
+    assert(!_resolutionEnqueuerCreated);
+    _resolutionEnqueuerCreated = true;
+    ResolutionEnqueuer enqueuer = compiler.frontendStrategy
         .createResolutionEnqueuer(this, compiler)
           ..onEmptyForTesting = compiler.onResolutionQueueEmptyForTesting;
+    if (retainDataForTesting) {
+      resolutionEnqueuerForTesting = enqueuer;
+    }
+    return enqueuer;
   }
 
   Enqueuer createCodegenEnqueuer(
@@ -241,7 +236,7 @@ class ResolutionEnqueuer extends EnqueuerImpl {
   final Set<ClassEntity> _recentClasses = new Setlet<ClassEntity>();
   bool _recentConstants = false;
   final ResolutionEnqueuerWorldBuilder _worldBuilder;
-  final WorkItemBuilder _workItemBuilder;
+  WorkItemBuilder _workItemBuilder;
   final DiagnosticReporter _reporter;
   final AnnotationsData _annotationsData;
 
@@ -492,6 +487,14 @@ class ResolutionEnqueuer extends EnqueuerImpl {
   @override
   bool get isResolutionQueue => true;
 
+  @override
+  void close() {
+    super.close();
+    // Null out _workItemBuilder to release memory (it internally holds large
+    // data-structures unnecessary after resolution.)
+    _workItemBuilder = null;
+  }
+
   /// Registers [entity] as processed by the resolution enqueuer. Used only for
   /// testing.
   void registerProcessedElementInternal(MemberEntity entity) {

pkg/compiler/lib/src/kernel/kernel_strategy.dart

@@ -81,9 +81,6 @@ class KernelFrontendStrategy extends FrontendStrategy {
 
   KFieldAnalysis _fieldAnalysis;
 
-  /// Backend transformation methods for the world impacts.
-  ImpactTransformer impactTransformer;
-
   @override
   NoSuchMethodRegistry noSuchMethodRegistry;
 
@@ -166,7 +163,7 @@ class KernelFrontendStrategy extends FrontendStrategy {
     // before creating the resolution enqueuer.
     AnnotationsData annotationsData = new AnnotationsDataImpl(
         compiler.options, annotationsDataBuilder.pragmaAnnotations);
-    impactTransformer = new JavaScriptImpactTransformer(
+    ImpactTransformer impactTransformer = new JavaScriptImpactTransformer(
         elementEnvironment,
         commonElements,
         impacts,

pkg/compiler/lib/src/universe/resolution_world_builder.dart

@@ -909,12 +909,6 @@ class ResolutionWorldBuilderImpl extends WorldBuilderBase
     }
   }
 
-  @override
-  Iterable<ClassEntity> allMixinUsesOf(ClassEntity cls) {
-    Iterable<ClassEntity> uses = _classHierarchyBuilder.mixinUses[cls];
-    return uses != null ? uses : const <ClassEntity>[];
-  }
-
   @override
   void registerUsedElement(MemberEntity element) {
     if (element.isInstanceMember && !element.isAbstract) {

pkg/compiler/lib/src/world.dart

@@ -216,9 +216,6 @@ abstract class OpenWorld implements World {
 
   KClosedWorld closeWorld(DiagnosticReporter reporter);
 
-  /// Returns an iterable over all mixin applications that mixin [cls].
-  Iterable<ClassEntity> allMixinUsesOf(ClassEntity cls);
-
   /// Returns `true` if [member] is inherited into a subtype of [type].
   ///
   /// For instance:

tests/compiler/dart2js/equivalence/id_equivalence_helper.dart

@@ -195,7 +195,7 @@ Future<CompiledData<T>> computeData<T>(Uri entryPoint,
   }
 
   dynamic closedWorld = testFrontend
-      ? compiler.resolutionWorldBuilder.closedWorldForTesting
+      ? compiler.frontendClosedWorldForTesting
       : compiler.backendClosedWorldForTesting;
   ElementEnvironment elementEnvironment = closedWorld?.elementEnvironment;
   CommonElements commonElements = closedWorld.commonElements;

tests/compiler/dart2js/helpers/type_test_helper.dart

@@ -147,8 +147,8 @@ class TypeEnvironment {
     MemberEntity member = _getMember(name, cls);
     DartType type;
 
-    for (KLocalFunction local in compiler
-        .resolutionWorldBuilder.closedWorldForTesting.localFunctions) {
+    for (KLocalFunction local
+        in compiler.frontendClosedWorldForTesting.localFunctions) {
       if (local.memberContext == member) {
         type ??= elementEnvironment.getLocalFunctionType(local);
       }
@@ -179,7 +179,7 @@ class TypeEnvironment {
 
   KClosedWorld get kClosedWorld {
     assert(!testBackendWorld);
-    return compiler.resolutionWorldBuilder.closedWorldForTesting;
+    return compiler.frontendClosedWorldForTesting;
   }
 }
 

tests/compiler/dart2js/inlining/meta_annotations_test.dart

@@ -36,8 +36,7 @@ main() {
     CompilationResult result =
         await runCompiler(memorySourceFiles: MEMORY_SOURCE_FILES);
     Compiler compiler = result.compiler;
-    KClosedWorld closedWorld =
-        compiler.resolutionWorldBuilder.closedWorldForTesting;
+    KClosedWorld closedWorld = compiler.frontendClosedWorldForTesting;
     KElementEnvironment elementEnvironment = closedWorld.elementEnvironment;
     Expect.isFalse(compiler.compilationFailed, 'Unsuccessful compilation');
 

tests/compiler/dart2js/member_usage/member_usage_test.dart

@@ -80,7 +80,7 @@ class ClosedWorldDataComputer extends DataComputer<Features> {
       {bool verbose: false}) {
     KernelFrontendStrategy frontendStrategy = compiler.frontendStrategy;
     ResolutionWorldBuilderImpl resolutionWorldBuilder =
-        compiler.resolutionWorldBuilder;
+        compiler.resolutionWorldBuilderForTesting;
     ir.Member node = frontendStrategy.elementMap.getMemberNode(member);
     Features features = new Features();
     MemberUsage memberUsage =

tests/compiler/dart2js/model/cfe_annotations_test.dart

@@ -443,7 +443,7 @@ main(List<String> args) {
         }
       }
 
-      testAll(compiler.resolutionWorldBuilder.closedWorldForTesting.nativeData);
+      testAll(compiler.frontendClosedWorldForTesting.nativeData);
       if (useIr) {
         testAll(new NativeDataImpl.fromIr(elementMap, annotationData));
       }

tests/compiler/dart2js/model/enqueuer_test.dart

@@ -162,7 +162,7 @@ main() {}
   void checkInvariant(
       Enqueuer enqueuer, ElementEnvironment elementEnvironment) {
     for (MemberEntity member
-        in compiler.enqueuer.resolution.processedEntities) {
+        in compiler.enqueuer.resolutionEnqueuerForTesting.processedEntities) {
       Expect.isTrue(
           member == elementEnvironment.mainFunction ||
               member.library != elementEnvironment.mainLibrary,
@@ -245,7 +245,7 @@ main() {}
   }
 
   compiler.onResolutionQueueEmptyForTesting = () {
-    Enqueuer enqueuer = compiler.enqueuer.resolution;
+    Enqueuer enqueuer = compiler.enqueuer.resolutionEnqueuerForTesting;
     ElementEnvironment elementEnvironment =
         compiler.frontendStrategy.elementEnvironment;
     checkInvariant(enqueuer, elementEnvironment);
@@ -278,7 +278,7 @@ main() {}
   await compiler.run(Uri.parse('memory:main.dart'));
 
   checkLiveMembers(
-      compiler.enqueuer.resolution,
+      compiler.enqueuer.resolutionEnqueuerForTesting,
       compiler.frontendStrategy.elementEnvironment,
       test.expectedLiveResolutionMap);
 

tests/compiler/dart2js/model/instantiated_classes_test.dart

@@ -30,7 +30,7 @@ void main() {
         return env.getElement(name);
       });
       Iterable<ClassEntity> actualClasses = env
-          .compiler.resolutionWorldBuilder.directlyInstantiatedClasses
+          .compiler.resolutionWorldBuilderForTesting.directlyInstantiatedClasses
           .where((c) => c.library == mainLibrary);
       Expect.setEquals(
           expectedClasses,

tests/compiler/dart2js/model/open_world_test.dart

@@ -92,7 +92,7 @@ ${liveClasses.map((c) => '  new $c();').join('\n')}
     ElementEnvironment elementEnvironment =
         compiler.frontendStrategy.elementEnvironment;
     nativeBasicData = compiler.frontendStrategy.nativeBasicData;
-    world = compiler.resolutionWorldBuilder;
+    world = compiler.resolutionWorldBuilderForTesting;
 
     ClassEntity findClass(String name) {
       ClassEntity cls =

tests/compiler/dart2js/model/strong_mode_closed_world_test.dart

@@ -196,8 +196,7 @@ method2() {
     'Class2': ['c'],
   };
 
-  KClosedWorld closedWorld =
-      compiler.resolutionWorldBuilder.closedWorldForTesting;
+  KClosedWorld closedWorld = compiler.frontendClosedWorldForTesting;
   ElementEnvironment elementEnvironment = closedWorld.elementEnvironment;
 
   elementEnvironment.forEachClass(elementEnvironment.mainLibrary,

tests/compiler/dart2js/model/strong_mode_impact_test.dart

@@ -77,8 +77,7 @@ main() {
   Expect.isTrue(result.isSuccess);
   Compiler compiler = result.compiler;
 
-  KClosedWorld closedWorld =
-      compiler.resolutionWorldBuilder.closedWorldForTesting;
+  KClosedWorld closedWorld = compiler.frontendClosedWorldForTesting;
   ElementEnvironment elementEnvironment = closedWorld.elementEnvironment;
 
   elementEnvironment.forEachLibraryMember(elementEnvironment.mainLibrary,

tests/compiler/dart2js/rti/rti_need_test_helper.dart

@@ -58,7 +58,7 @@ abstract class ComputeValueMixin {
 
   KernelFrontendStrategy get frontendStrategy => compiler.frontendStrategy;
   ResolutionWorldBuilder get resolutionWorldBuilder =>
-      compiler.resolutionWorldBuilder;
+      compiler.resolutionWorldBuilderForTesting;
   RuntimeTypesNeedBuilderImpl get rtiNeedBuilder =>
       frontendStrategy.runtimeTypesNeedBuilderForTesting;
   RuntimeTypesNeedImpl get rtiNeed =>
@@ -275,8 +275,8 @@ class RtiNeedDataComputer extends DataComputer<String> {
 abstract class IrMixin implements ComputeValueMixin {
   @override
   MemberEntity getFrontendMember(MemberEntity backendMember) {
-    ElementEnvironment elementEnvironment = compiler
-        .resolutionWorldBuilder.closedWorldForTesting.elementEnvironment;
+    ElementEnvironment elementEnvironment =
+        compiler.frontendClosedWorldForTesting.elementEnvironment;
     LibraryEntity frontendLibrary =
         elementEnvironment.lookupLibrary(backendMember.library.canonicalUri);
     if (backendMember.enclosingClass != null) {
@@ -300,8 +300,8 @@ abstract class IrMixin implements ComputeValueMixin {
   @override
   ClassEntity getFrontendClass(ClassEntity backendClass) {
     if (backendClass.isClosure) return null;
-    ElementEnvironment elementEnvironment = compiler
-        .resolutionWorldBuilder.closedWorldForTesting.elementEnvironment;
+    ElementEnvironment elementEnvironment =
+        compiler.frontendClosedWorldForTesting.elementEnvironment;
     LibraryEntity frontendLibrary =
         elementEnvironment.lookupLibrary(backendClass.library.canonicalUri);
     return elementEnvironment.lookupClass(frontendLibrary, backendClass.name);