Change the type inference for fields in dart2js

lib/compiler/implementation/js_backend/backend.dart

Index: lib/compiler/implementation/js_backend/backend.dart
diff --git a/lib/compiler/implementation/js_backend/backend.dart b/lib/compiler/implementation/js_backend/backend.dart
index 144349642956c5eaad3266515c82aa4465b200ff..0880f60a67bbce964f5b21024e1efb97278893ff 100644
--- a/lib/compiler/implementation/js_backend/backend.dart
+++ b/lib/compiler/implementation/js_backend/backend.dart
@@ -223,6 +223,120 @@ class HTypeList {
       allUnknown ? "HTypeList.ALL_UNKNOWN" : "HTypeList $types";
 }
 
+class FieldTypesRegistry {
+  final JavaScriptBackend backend;
+  final Map<Element, HType> fieldInitializerTypeMap;
+  final Map<Element, HType> fieldConstructorTypeMap;
+  final Map<Element, HType> fieldTypeMap;
+  final Map<Element, FunctionSet> optimizedFunctions;
+
+  FieldTypesRegistry(JavaScriptBackend backend)
+      : fieldInitializerTypeMap = new Map<Element, HType>(),
+        fieldConstructorTypeMap = new Map<Element, HType>(),
+        fieldTypeMap = new Map<Element, HType>(),
+        optimizedFunctions = new Map<Element, FunctionSet>(),
+        this.backend = backend;
+
+  Compiler get compiler => backend.compiler;
+
+  void scheduleRecompilation(Element field) {
+    FunctionSet optimized = optimizedFunctions[field];
+    if (optimized != null) {
+      optimized.forEach(backend.scheduleForRecompilation);
+    }
+    optimizedFunctions.remove(field);
+  }
+
+  void registerFieldType(Map<Element, HType> typeMap,
+                         Element field,
+                         HType type) {
+    assert(field.isField());
+    HType oldType = typeMap[field];
+    HType newType;
+
+    if (oldType != null) {
+      newType = oldType.union(type);
+    } else {
+      newType = type;
+    }
+    typeMap[field] = newType;
+    if (oldType != newType) {
+      scheduleRecompilation(field);
+    }
+  }
+
+  void registerFieldInitializer(Element field, HType type) {
+    registerFieldType(fieldInitializerTypeMap, field, type);
+  }
+
+  void registerFieldConstructor(Element field, HType type) {
+    registerFieldType(fieldConstructorTypeMap, field, type);
+  }
+
+  void registerFieldSetter(HFieldSet node, HTypeMap types) {
+    Element field = node.element;
+    HType initializerType = fieldInitializerTypeMap[field];
+    HType constructorType = fieldConstructorTypeMap[field];
+    HType setterType = fieldTypeMap[field];
+    HType type = types[node.value];
+    // No need to register UNKONWN if there is currently no type information
+    // present for the field.
+    if (type == HType.UNKNOWN &&
+        initializerType == null &&
+        constructorType == null &&
+        setterType == null) {
+      return;
+    }
+    registerFieldType(fieldTypeMap, field, type);
+  }
+
+  void addedDynamicSetter(Selector setter) {
+    optimizedFunctions.forEach((Element field, _) {
+      if (field.name == setter.name) {
+        if (compiler.codegenWorld.hasInvokedSetter(field, compiler)) {
+          scheduleRecompilation(field);
+        }
+      }
+    });
+  }
+
+  HType optimisticFieldType(Element field) {
+    assert(field.isField());
+    assert(field.isMember());
+    if (compiler.codegenWorld.hasInvokedSetter(field, compiler)) {
+      return HType.UNKNOWN;
+    }
+    HType initializerType = fieldInitializerTypeMap[field];
+    HType constructorType = fieldConstructorTypeMap[field];
+    if (initializerType === null && constructorType === null) {
+      return HType.UNKNOWN;
+    }
+    HType result = constructorType != null ? constructorType : initializerType;
+    HType type = fieldTypeMap[field];
+    if (type !== null) result = result.union(type);
+    return result;
+  }
+
+  void registerOptimizedFunction(FunctionElement element,
+                                 Element field,
+                                 HType type) {
+    assert(field.isField());
+    optimizedFunctions.putIfAbsent(
+        field, () => new FunctionSet(backend.compiler));
+    optimizedFunctions[field].add(element);
+  }
+
+  void dump() {
+    Set<Element> allFields = new Set<Element>();
+    fieldInitializerTypeMap.getKeys().forEach(allFields.add);
+    fieldConstructorTypeMap.getKeys().forEach(allFields.add);
+    fieldTypeMap.getKeys().forEach(allFields.add);
+    allFields.forEach((Element field) {
+      print("Inferred $field has type ${optimisticFieldType(field)}");
+    });
+  }
+}
+
 class ArgumentTypesRegistry {
   final JavaScriptBackend backend;
 
@@ -385,10 +499,9 @@ class ArgumentTypesRegistry {
     return found !== null ? found : HTypeList.ALL_UNKNOWN;
   }
 
-  void registerOptimization(Element element,
-                            HTypeList parameterTypes,
-                            OptionalParameterTypes defaultValueTypes) {
-    assert(invariant(element, element.isDeclaration));
+  void registerOptimizedFunction(Element element,
+                                 HTypeList parameterTypes,
+                                 OptionalParameterTypes defaultValueTypes) {
     if (Elements.isStaticOrTopLevelFunction(element)) {
       if (parameterTypes.allUnknown) {
         optimizedStaticFunctions.remove(element);
@@ -443,10 +556,6 @@ class JavaScriptBackend extends Backend {
    */
   ClassElement jsIndexingBehaviorInterface;
 
-  final Map<Element, Map<Element, HType>> fieldInitializers;
-  final Map<Element, Map<Element, HType>> fieldConstructorSetters;
-  final Map<Element, Map<Element, HType>> fieldSettersType;
-
   final Map<Element, ReturnInfo> returnInfo;
 
   /**
@@ -456,16 +565,14 @@ class JavaScriptBackend extends Backend {
    */
   final List<Element> invalidateAfterCodegen;
   ArgumentTypesRegistry argumentTypes;
+  FieldTypesRegistry fieldTypes;
 
   List<CompilerTask> get tasks {
     return <CompilerTask>[builder, optimizer, generator, emitter];
   }
 
   JavaScriptBackend(Compiler compiler, bool generateSourceMap)
-      : fieldInitializers = new Map<Element, Map<Element, HType>>(),
-        fieldConstructorSetters = new Map<Element, Map<Element, HType>>(),
-        fieldSettersType = new Map<Element, Map<Element, HType>>(),
-        namer = new Namer(compiler),
+      : namer = new Namer(compiler),
         returnInfo = new Map<Element, ReturnInfo>(),
         invalidateAfterCodegen = new List<Element>(),
         super(compiler, constantSystem: JAVA_SCRIPT_CONSTANT_SYSTEM) {
@@ -474,6 +581,7 @@ class JavaScriptBackend extends Backend {
     optimizer = new SsaOptimizerTask(this);
     generator = new SsaCodeGeneratorTask(this);
     argumentTypes = new ArgumentTypesRegistry(this);
+    fieldTypes = new FieldTypesRegistry(this);
   }
 
   Element get cyclicThrowHelper {
@@ -539,106 +647,6 @@ class JavaScriptBackend extends Backend {
     emitter.assembleProgram();
   }
 
-  void updateFieldInitializers(Element field, HType propagatedType) {
-    assert(field.isField());
-    assert(field.isMember());
-    Map<Element, HType> fields =
-        fieldInitializers.putIfAbsent(
-          field.getEnclosingClass(), () => new Map<Element, HType>());
-    if (!fields.containsKey(field)) {
-      fields[field] = propagatedType;
-    } else {
-      fields[field] = fields[field].union(propagatedType);
-    }
-  }
-
-  HType typeFromInitializersSoFar(Element field) {
-    assert(field.isField());
-    assert(field.isMember());
-    if (!fieldInitializers.containsKey(field.getEnclosingClass())) {
-      return HType.CONFLICTING;
-    }
-    Map<Element, HType> fields = fieldInitializers[field.getEnclosingClass()];
-    return fields[field];
-  }
-
-  void updateFieldConstructorSetters(Element field, HType type) {
-    assert(field.isField());
-    assert(field.isMember());
-    Map<Element, HType> fields =
-        fieldConstructorSetters.putIfAbsent(
-            field.getEnclosingClass(), () => new Map<Element, HType>());
-    if (!fields.containsKey(field)) {
-      fields[field] = type;
-    } else {
-      fields[field] = fields[field].union(type);
-    }
-  }
-
-  // Check if this field is set in the constructor body.
-  bool hasConstructorBodyFieldSetter(Element field) {
-    ClassElement enclosingClass = field.getEnclosingClass();
-    if (!fieldConstructorSetters.containsKey(enclosingClass)) {
-      return false;
-    }
-    return fieldConstructorSetters[enclosingClass][field] != null;
-  }
-
-  // Provide an optimistic estimate of the type of a field after construction.
-  // If the constructor body has setters for fields returns HType.UNKNOWN.
-  // This only takes the initializer lists and field assignments in the
-  // constructor body into account. The constructor body might have method calls
-  // that could alter the field.
-  HType optimisticFieldTypeAfterConstruction(Element field) {
-    assert(field.isField());
-    assert(field.isMember());
-
-    ClassElement classElement = field.getEnclosingClass();
-    if (hasConstructorBodyFieldSetter(field)) {
-      // If there are field setters but there is only constructor then the type
-      // of the field is determined by the assignments in the constructor
-      // body.
-      var constructors = classElement.constructors;
-      if (constructors.head !== null && constructors.tail.isEmpty()) {
-        return fieldConstructorSetters[classElement][field];
-      } else {
-        return HType.UNKNOWN;
-      }
-    } else if (fieldInitializers.containsKey(classElement)) {
-      HType type = fieldInitializers[classElement][field];
-      return type == null ? HType.CONFLICTING : type;
-    } else {
-      return HType.CONFLICTING;
-    }
-  }
-
-  void updateFieldSetters(Element field, HType type) {
-    assert(field.isField());
-    assert(field.isMember());
-    Map<Element, HType> fields =
-        fieldSettersType.putIfAbsent(
-          field.getEnclosingClass(), () => new Map<Element, HType>());
-    if (!fields.containsKey(field)) {
-      fields[field] = type;
-    } else {
-      fields[field] = fields[field].union(type);
-    }
-  }
-
-  // Returns the type that field setters are setting the field to based on what
-  // have been seen during compilation so far.
-  HType fieldSettersTypeSoFar(Element field) {
-    assert(field.isField());
-    assert(field.isMember());
-    ClassElement enclosingClass = field.getEnclosingClass();
-    if (!fieldSettersType.containsKey(enclosingClass)) {
-      return HType.CONFLICTING;
-    }
-    Map<Element, HType> fields = fieldSettersType[enclosingClass];
-    if (!fields.containsKey(field)) return HType.CONFLICTING;
-    return fields[field];
-  }
-
   /**
    * Documentation wanted -- johnniwinther
    *
@@ -707,10 +715,16 @@ class JavaScriptBackend extends Backend {
       OptionalParameterTypes defaultValueTypes) {
     assert(invariant(element, element.isDeclaration));
     if (element.parameterCount(compiler) == 0) return;
-    argumentTypes.registerOptimization(
+    argumentTypes.registerOptimizedFunction(
         element, parameterTypes, defaultValueTypes);
   }
 
+  registerFieldTypesOptimization(FunctionElement element,
+                                 Element field,
+                                 HType type) {
+    fieldTypes.registerOptimizedFunction(element, field, type);
+  }
+
   /**
    * Documentation wanted -- johnniwinther
    *
@@ -755,6 +769,26 @@ class JavaScriptBackend extends Backend {
     });
   }
 
+  void registerFieldInitializer(Element field, HType type) {
+    fieldTypes.registerFieldInitializer(field, type);
+  }
+
+  void registerFieldConstructor(Element field, HType type) {
+    fieldTypes.registerFieldConstructor(field, type);
+  }
+
+  void registerFieldSetter(HFieldSet node, HTypeMap types) {
+    fieldTypes.registerFieldSetter(node, types);
+  }
+
+  void addedDynamicSetter(Selector setter) {
+    fieldTypes.addedDynamicSetter(setter);
+  }
+
+  HType optimisticFieldType(Element element) {
+    return fieldTypes.optimisticFieldType(element);
+  }
+
   SourceString getCheckedModeHelper(DartType type) {
     Element element = type.element;
     bool nativeCheck =