Remove Enqueuer argument from Backend.registerStaticUse

- and from CustomElementsAnalysis, TypeVariableHandler, and LookupMapAnalysis methods

R=sigmund@google.com

Review URL: https://codereview.chromium.org/2378063002 .

pkg/compiler/lib/src/common/backend_api.dart

@@ -213,7 +213,7 @@ abstract class Backend extends Target {
     return false;
   }
 
-  void registerStaticUse(Element element, Enqueuer enqueuer) {}
+  void registerStaticUse(Element element, {bool forResolution}) {}
 
   /// This method is called immediately after the [LibraryElement] [library] has
   /// been created.

pkg/compiler/lib/src/compiler.dart

@@ -835,9 +835,9 @@ abstract class Compiler implements LibraryLoaderListener {
               work.element,
               () => selfTask.measureSubtask("world.applyImpact", () {
                     world.applyImpact(
-                        work.element,
                         selfTask.measureSubtask(
-                            "work.run", () => work.run(this, world)));
+                            "work.run", () => work.run(this, world)),
+                        impactSource: work.element);
                   }));
         });
       });

pkg/compiler/lib/src/enqueue.dart

@@ -110,7 +110,11 @@ abstract class Enqueuer {
 
   void registerInstantiatedType(InterfaceType type, {bool mirrorUsage: false});
   void forEach(void f(WorkItem work));
-  void applyImpact(Element element, WorldImpact worldImpact);
+
+  /// Apply the [worldImpact] to this enqueuer. If the [impactSource] is provided
+  /// the impact strategy will remove it from the element impact cache, if it is
+  /// no longer needed.
+  void applyImpact(WorldImpact worldImpact, {Element impactSource});
   bool checkNoEnqueuedInvokedInstanceMethods();
   void logSummary(log(message));
 
@@ -183,10 +187,9 @@ class ResolutionEnqueuer extends Enqueuer {
     }
   }
 
-  /// Apply the [worldImpact] of processing [element] to this enqueuer.
-  void applyImpact(Element element, WorldImpact worldImpact) {
+  void applyImpact(WorldImpact worldImpact, {Element impactSource}) {
     compiler.impactStrategy
-        .visitImpact(element, worldImpact, impactVisitor, impactUse);
+        .visitImpact(impactSource, worldImpact, impactVisitor, impactUse);
   }
 
   void registerInstantiatedType(InterfaceType type, {bool mirrorUsage: false}) {
@@ -574,7 +577,7 @@ class ResolutionEnqueuer extends Enqueuer {
     assert(invariant(element, element.isDeclaration,
         message: "Element ${element} is not the declaration."));
     _universe.registerStaticUse(staticUse);
-    compiler.backend.registerStaticUse(element, this);
+    compiler.backend.registerStaticUse(element, forResolution: true);
     bool addElement = true;
     switch (staticUse.kind) {
       case StaticUseKind.STATIC_TEAR_OFF:

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

@@ -1310,7 +1310,8 @@ class JavaScriptBackend extends Backend {
       enqueue(enqueuer, helpers.isJsIndexable, registry);
     }
 
-    customElementsAnalysis.registerInstantiatedClass(cls, enqueuer);
+    customElementsAnalysis.registerInstantiatedClass(cls,
+        forResolution: enqueuer.isResolutionQueue);
     if (!enqueuer.isResolutionQueue) {
       lookupMapAnalysis.registerInstantiatedClass(cls);
     }
@@ -1904,7 +1905,7 @@ class JavaScriptBackend extends Backend {
     return compiler.closedWorld.hasOnlySubclasses(classElement);
   }
 
-  void registerStaticUse(Element element, Enqueuer enqueuer) {
+  void registerStaticUse(Element element, {bool forResolution}) {
     if (element == helpers.disableTreeShakingMarker) {
       isTreeShakingDisabled = true;
     } else if (element == helpers.preserveNamesMarker) {
@@ -1927,7 +1928,8 @@ class JavaScriptBackend extends Backend {
     } else if (element == helpers.requiresPreambleMarker) {
       requiresPreamble = true;
     }
-    customElementsAnalysis.registerStaticUse(element, enqueuer);
+    customElementsAnalysis.registerStaticUse(element,
+        forResolution: forResolution);
   }
 
   /// Called when [:const Symbol(name):] is seen.
@@ -2351,9 +2353,12 @@ class JavaScriptBackend extends Backend {
     //
     // Return early if any elements are added to avoid counting the elements as
     // due to mirrors.
-    customElementsAnalysis.onQueueEmpty(enqueuer);
-    lookupMapAnalysis.onQueueEmpty(enqueuer);
-    typeVariableHandler.onQueueEmpty(enqueuer);
+    enqueuer.applyImpact(customElementsAnalysis.flush(
+        forResolution: enqueuer.isResolutionQueue));
+    enqueuer.applyImpact(
+        lookupMapAnalysis.flush(forResolution: enqueuer.isResolutionQueue));
+    enqueuer.applyImpact(
+        typeVariableHandler.flush(forResolution: enqueuer.isResolutionQueue));
 
     if (!enqueuer.queueIsEmpty) return false;
 
@@ -2424,7 +2429,7 @@ class JavaScriptBackend extends Backend {
         }
         metadataConstants.clear();
       }
-      enqueuer.applyImpact(null, impactBuilder.flush());
+      enqueuer.applyImpact(impactBuilder.flush());
     }
     return true;
   }

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

@@ -71,10 +71,11 @@ class CustomElementsAnalysis {
     codegenJoin.allClassesSelected = true;
   }
 
-  CustomElementsAnalysisJoin joinFor(Enqueuer enqueuer) =>
-      enqueuer.isResolutionQueue ? resolutionJoin : codegenJoin;
+  CustomElementsAnalysisJoin joinFor({bool forResolution}) =>
+      forResolution ? resolutionJoin : codegenJoin;
 
-  void registerInstantiatedClass(ClassElement classElement, Enqueuer enqueuer) {
+  void registerInstantiatedClass(ClassElement classElement,
+      {bool forResolution}) {
     classElement.ensureResolved(compiler.resolution);
     if (!backend.isNativeOrExtendsNative(classElement)) return;
     if (classElement.isMixinApplication) return;
@@ -82,7 +83,7 @@ class CustomElementsAnalysis {
     // JsInterop classes are opaque interfaces without a concrete
     // implementation.
     if (backend.isJsInterop(classElement)) return;
-    joinFor(enqueuer).instantiatedClasses.add(classElement);
+    joinFor(forResolution: forResolution).instantiatedClasses.add(classElement);
   }
 
   void registerTypeLiteral(DartType type) {
@@ -104,19 +105,20 @@ class CustomElementsAnalysis {
     codegenJoin.selectedClasses.add(element);
   }
 
-  void registerStaticUse(Element element, Enqueuer enqueuer) {
+  void registerStaticUse(Element element, {bool forResolution}) {
     assert(element != null);
     if (!fetchedTableAccessorMethod) {
       fetchedTableAccessorMethod = true;
       tableAccessorMethod = backend.helpers.findIndexForNativeSubclassType;
     }
     if (element == tableAccessorMethod) {
-      joinFor(enqueuer).demanded = true;
+      joinFor(forResolution: forResolution).demanded = true;
     }
   }
 
-  void onQueueEmpty(Enqueuer enqueuer) {
-    joinFor(enqueuer).flush(enqueuer);
+  /// Computes the [WorldImpact] of the classes registered since last flush.
+  WorldImpact flush({bool forResolution}) {
+    return joinFor(forResolution: forResolution).flush();
   }
 
   bool get needsTable => codegenJoin.demanded;
@@ -152,8 +154,8 @@ class CustomElementsAnalysisJoin {
 
   CustomElementsAnalysisJoin(this.backend);
 
-  void flush(Enqueuer enqueuer) {
-    if (!demanded) return;
+  WorldImpact flush() {
+    if (!demanded) return const WorldImpact();
     var newActiveClasses = new Set<ClassElement>();
     for (ClassElement classElement in instantiatedClasses) {
       bool isNative = backend.isNative(classElement);
@@ -168,7 +170,8 @@ class CustomElementsAnalysisJoin {
         Iterable<ConstructorElement> escapingConstructors =
             computeEscapingConstructors(classElement);
         for (ConstructorElement constructor in escapingConstructors) {
-          enqueuer.registerStaticUse(new StaticUse.foreignUse(constructor));
+          impactBuilder
+              .registerStaticUse(new StaticUse.foreignUse(constructor));
         }
         escapingConstructors
             .forEach(compiler.globalDependencies.registerDependency);
@@ -182,7 +185,7 @@ class CustomElementsAnalysisJoin {
     }
     activeClasses.addAll(newActiveClasses);
     instantiatedClasses.removeAll(newActiveClasses);
-    enqueuer.applyImpact(null, impactBuilder.flush());
+    return impactBuilder.flush();
   }
 
   TypeConstantValue makeTypeConstant(ClassElement element) {

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

@@ -134,10 +134,9 @@ class CodegenEnqueuer implements Enqueuer {
     }
   }
 
-  /// Apply the [worldImpact] of processing [element] to this enqueuer.
-  void applyImpact(Element element, WorldImpact worldImpact) {
+  void applyImpact(WorldImpact worldImpact, {Element impactSource}) {
     _compiler.impactStrategy
-        .visitImpact(element, worldImpact, impactVisitor, impactUse);
+        .visitImpact(impactSource, worldImpact, impactVisitor, impactUse);
   }
 
   void registerInstantiatedType(InterfaceType type, {bool mirrorUsage: false}) {
@@ -513,7 +512,7 @@ class CodegenEnqueuer implements Enqueuer {
     assert(invariant(element, element.isDeclaration,
         message: "Element ${element} is not the declaration."));
     _universe.registerStaticUse(staticUse);
-    backend.registerStaticUse(element, this);
+    backend.registerStaticUse(element, forResolution: false);
     bool addElement = true;
     switch (staticUse.kind) {
       case StaticUseKind.STATIC_TEAR_OFF:

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

@@ -128,9 +128,10 @@ class LookupMapAnalysis {
 
   LookupMapAnalysis(this.backend, this.reporter);
 
-  void onQueueEmpty(Enqueuer enqueuer) {
-    if (enqueuer.isResolutionQueue) return;
-    enqueuer.applyImpact(null, impactBuilder.flush());
+  /// Compute the [WorldImpact] for the constants registered since last flush.
+  WorldImpact flush({bool forResolution}) {
+    if (forResolution) return const WorldImpact();
+    return impactBuilder.flush();
   }
 
   /// Whether this analysis and optimization is enabled.

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

@@ -57,10 +57,11 @@ class TypeVariableHandler {
   JavaScriptBackend get _backend => _compiler.backend;
   DiagnosticReporter get reporter => _compiler.reporter;
 
-  void onQueueEmpty(Enqueuer enqueuer) {
-    if (enqueuer.isResolutionQueue) return;
-
-    enqueuer.applyImpact(null, impactBuilder.flush());
+  /// Compute the [WorldImpact] for the type variables registered since last
+  /// flush.
+  WorldImpact flush({bool forResolution}) {
+    if (forResolution) return const WorldImpact();
+    return impactBuilder.flush();
   }
 
   void registerClassWithTypeVariables(

pkg/compiler/lib/src/ssa/builder.dart

@@ -377,7 +377,7 @@ class SsaBuilder extends ast.Visitor
     // TODO(johnniwinther): Register this on the [registry]. Currently the
     // [CodegenRegistry] calls the enqueuer, but [element] should _not_ be
     // enqueued.
-    backend.registerStaticUse(element, compiler.enqueuer.codegen);
+    backend.registerStaticUse(element, forResolution: false);
 
     if (backend.isJsInterop(element) && !element.isFactoryConstructor) {
       // We only inline factory JavaScript interop constructors.