Remove WorldImpact from caches when no longer needed.

pkg/compiler/lib/src/compiler.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.
 
 library dart2js.compiler_base;
 
 import 'dart:async' show
     EventSink,
     Future;
 
@@ skipping 119 matching lines @@
 import 'types/types.dart' as ti;
 import 'universe/call_structure.dart' show
     CallStructure;
 import 'universe/selector.dart' show
     Selector;
 import 'universe/universe.dart' show
     Universe;
 import 'universe/use.dart' show
     StaticUse;
 import 'universe/world_impact.dart' show
+    ImpactStrategy,
     WorldImpact;
 import 'util/util.dart' show
     Link,
     Setlet;
 import 'world.dart' show
     World;
 
 abstract class Compiler {
 
   final Stopwatch totalCompileTime = new Stopwatch();
   int nextFreeClassId = 0;
   World world;
   Types types;
   _CompilerCoreTypes _coreTypes;
   _CompilerDiagnosticReporter _reporter;
   _CompilerResolution _resolution;
   _CompilerParsing _parsing;
 
   final CacheStrategy cacheStrategy;
 
+  ImpactStrategy impactStrategy = const ImpactStrategy();
+
   /**
    * Map from token to the first preceding comment token.
    */
   final TokenMap commentMap = new TokenMap();
 
   /**
    * Records global dependencies, that is, dependencies that don't
    * correspond to a particular element.
    *
    * We should get rid of this and ensure that all dependencies are
@@ skipping 798 matching lines @@
   void compileLoadedLibraries() {
     computeMain();
 
     mirrorUsageAnalyzerTask.analyzeUsage(mainApp);
 
     // In order to see if a library is deferred, we must compute the
     // compile-time constants that are metadata.  This means adding
     // something to the resolution queue.  So we cannot wait with
     // this until after the resolution queue is processed.
     deferredLoadTask.beforeResolution(this);
+    impactStrategy = backend.createImpactStrategy(
+        supportDeferredLoad: deferredLoadTask.isProgramSplit,
+        supportDumpInfo: dumpInfo);
 
     phase = PHASE_RESOLVING;
     if (analyzeAll) {
       libraryLoader.libraries.forEach((LibraryElement library) {
       reporter.log('Enqueuing ${library.canonicalUri}');
         fullyEnqueueLibrary(library, enqueuer.resolution);
       });
     } else if (analyzeMain) {
       if (mainApp != null) {
         fullyEnqueueLibrary(mainApp, enqueuer.resolution);
@@ skipping 1024 matching lines @@
         compiler.checker.check(element);
       }
       WorldImpact worldImpact =
           compiler.backend.impactTransformer.transformResolutionImpact(
               resolutionImpact);
       return worldImpact;
     });
   }
 
   @override
+  void uncacheWorldImpact(Element element) {
+    assert(invariant(element, _worldImpactCache[element] != null,
+        message: "WorldImpact not computed for $element."));
+    _worldImpactCache[element] = const WorldImpact();
+  }
+
+  @override
   bool hasBeenResolved(Element element) {
     return _worldImpactCache.containsKey(element);
   }
 }
 
 // TODO(johnniwinther): Move [ParserTask], [PatchParserTask], [DietParserTask]
 // and [ScannerTask] here.
 class _CompilerParsing implements Parsing {
   final Compiler compiler;
 
@@ skipping 36 matching lines @@
     if (_otherDependencies == null) {
       _otherDependencies = new Setlet<Element>();
     }
     _otherDependencies.add(element.implementation);
   }
 
   Iterable<Element> get otherDependencies {
     return _otherDependencies != null ? _otherDependencies : const <Element>[];
   }
 }