Remove direct access to enqueuer through use of WorldImpact

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

 // Copyright (c) 2015, 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.
 
 /// Analysis to determine how to generate code for `LookupMap`s.
 library compiler.src.js_backend.lookup_map_analysis;
 
 import 'package:pub_semver/pub_semver.dart';
 
 import '../common.dart';
 import '../compiler.dart' show Compiler;
 import '../constants/values.dart'
     show
         ConstantValue,
         ConstructedConstantValue,
         ListConstantValue,
         NullConstantValue,
         StringConstantValue,
         TypeConstantValue;
 import '../dart_types.dart' show DartType;
 import '../dart_types.dart' show InterfaceType;
 import '../elements/elements.dart'
     show ClassElement, FieldElement, LibraryElement, VariableElement;
-import '../enqueue.dart';
+import '../universe/use.dart' show StaticUse;
 import '../universe/world_impact.dart'
     show WorldImpact, StagedWorldImpactBuilder;
 import 'js_backend.dart' show JavaScriptBackend;
 
 /// An analysis and optimization to remove unused entries from a `LookupMap`.
 ///
 /// `LookupMaps` are defined in `package:lookup_map/lookup_map.dart`. They are
 /// simple maps that contain constant expressions as keys, and that only support
 /// the lookup operation.
 ///
@@ skipping 78 matching lines @@
   /// runtime. Technically if we limit lookup-maps to check for identical keys,
   /// we could allow const instances of these types.  However, we internally use
   /// a hash map within lookup-maps today, so we need this restriction.
   final _typesWithEquals = <ClassElement, bool>{};
 
   /// Pending work to do if we discover that a new key is in use. For each key
   /// that we haven't seen, we record the list of lookup-maps that contain an
   /// entry with that key.
   final _pending = <ConstantValue, List<_LookupMapInfo>>{};
 
-  final StagedWorldImpactBuilder impactBuilder = new StagedWorldImpactBuilder();
+  final StagedWorldImpactBuilder impactBuilderForResolution =
+      new StagedWorldImpactBuilder();
+  final StagedWorldImpactBuilder impactBuilderForCodegen =
+      new StagedWorldImpactBuilder();
 
   /// Whether the backend is currently processing the codegen queue.
   bool _inCodegen = false;
 
   LookupMapAnalysis(this.backend, this.reporter);
 
   /// Compute the [WorldImpact] for the constants registered since last flush.
   WorldImpact flush({bool forResolution}) {
-    if (forResolution) return const WorldImpact();
-    return impactBuilder.flush();
+    if (forResolution) {
+      return impactBuilderForResolution.flush();
+    } else {
+      return impactBuilderForCodegen.flush();
+    }
   }
 
   /// Whether this analysis and optimization is enabled.
   bool get _isEnabled {
     // `lookupMap==off` kept here to make it easy to test disabling this feature
     if (const String.fromEnvironment('lookupMap') == 'off') return false;
     return typeLookupMapClass != null;
   }
 
   /// Initializes this analysis by providing the resolved library. This is
   /// invoked during resolution when the `lookup_map` library is discovered.
   void init(LibraryElement library) {
     lookupMapLibrary = library;
     // We will enable the lookupMapAnalysis as long as we get a known version of
     // the lookup_map package. We otherwise produce a warning.
     lookupMapVersionVariable = library.implementation.findLocal('_version');
     if (lookupMapVersionVariable == null) {
       reporter.reportInfo(
           library, MessageKind.UNRECOGNIZED_VERSION_OF_LOOKUP_MAP);
     } else {
-      backend.compiler.enqueuer.resolution
-          .addToWorkList(lookupMapVersionVariable);
+      impactBuilderForResolution.registerStaticUse(
+          new StaticUse.foreignUse(lookupMapVersionVariable));
     }
   }
 
   /// Checks if the version of lookup_map is valid, and if so, enable this
   /// analysis during codegen.
   void onCodegenStart() {
     _inCodegen = true;
     if (lookupMapVersionVariable == null) return;
 
     // At this point, the lookupMapVersionVariable should be resolved and it's
@@ skipping 104 matching lines @@
   /// returned using a type-argument expression.
   void _addGenerics(InterfaceType type) {
     if (!type.isGeneric) return;
     for (var arg in type.typeArguments) {
       if (arg is InterfaceType) {
         _addClassUse(arg.element);
         // Note: this call was needed to generate correct code for
         // type_lookup_map/generic_type_test
         // TODO(sigmund): can we get rid of this?
         backend.computeImpactForInstantiatedConstantType(
-            backend.backendClasses.typeImplementation.rawType, impactBuilder);
+            backend.backendClasses.typeImplementation.rawType,
+            impactBuilderForCodegen);
         _addGenerics(arg);
       }
     }
   }
 
   /// Callback from the codegen enqueuer, invoked when a constant (which is
   /// possibly a const key or a type literal) is used in the program.
   void registerTypeConstant(ClassElement element) {
     if (!_isEnabled || !_inCodegen) return;
     _addClassUse(element);
@@ skipping 120 matching lines @@
 
   /// Marks that [key] has been seen, and thus, the corresponding entry in this
   /// map should be considered reachable.
   _markUsed(ConstantValue key) {
     assert(!emitted);
     assert(unusedEntries.containsKey(key));
     assert(!usedEntries.containsKey(key));
     ConstantValue constant = unusedEntries.remove(key);
     usedEntries[key] = constant;
     analysis.backend.computeImpactForCompileTimeConstant(
-        constant, analysis.impactBuilder, false);
+        constant, analysis.impactBuilderForCodegen, false);
   }
 
   /// Restores [original] to contain all of the entries marked as possibly used.
   void _prepareForEmission() {
     ListConstantValue originalEntries = original.fields[analysis.entriesField];
     DartType listType = originalEntries.type;
     List<ConstantValue> keyValuePairs = <ConstantValue>[];
     usedEntries.forEach((key, value) {
       keyValuePairs.add(key);
       keyValuePairs.add(value);
     });
 
     // Note: we are restoring the entries here, see comment in [original].
     if (singlePair) {
       assert(keyValuePairs.length == 0 || keyValuePairs.length == 2);
       if (keyValuePairs.length == 2) {
         original.fields[analysis.keyField] = keyValuePairs[0];
         original.fields[analysis.valueField] = keyValuePairs[1];
       }
     } else {
       original.fields[analysis.entriesField] =
           new ListConstantValue(listType, keyValuePairs);
     }
   }
 }
 
 final _validLookupMapVersionConstraint = new VersionConstraint.parse('^0.0.1');