[turbofan] Refactor the lowering of element/property accesses.

src/compiler/access-info.h

Index: src/compiler/access-info.h
diff --git a/src/compiler/access-info.h b/src/compiler/access-info.h
index 1556e0ee3838482ddcca8f07d4deaeefa3df7a9f..bca7d5d83757432296d7f0b6562a7dd180fae125 100644
--- a/src/compiler/access-info.h
+++ b/src/compiler/access-info.h
@@ -19,7 +19,6 @@ class CompilationDependencies;
 class Factory;
 class TypeCache;
 
-
 namespace compiler {
 
 // Whether we are loading a property or storing to a property.
@@ -27,50 +26,51 @@ enum class AccessMode { kLoad, kStore };
 
 std::ostream& operator<<(std::ostream&, AccessMode);
 
+typedef std::vector<Handle<Map>> MapList;
 
 // Mapping of transition source to transition target.
 typedef std::vector<std::pair<Handle<Map>, Handle<Map>>> MapTransitionList;
 
-
 // This class encapsulates all information required to access a certain element.
 class ElementAccessInfo final {
  public:
   ElementAccessInfo();
-  ElementAccessInfo(Type* receiver_type, ElementsKind elements_kind,
+  ElementAccessInfo(MapList const& receiver_maps, ElementsKind elements_kind,
                     MaybeHandle<JSObject> holder);
 
   MaybeHandle<JSObject> holder() const { return holder_; }
   ElementsKind elements_kind() const { return elements_kind_; }
-  Type* receiver_type() const { return receiver_type_; }
+  MapList const& receiver_maps() const { return receiver_maps_; }
   MapTransitionList& transitions() { return transitions_; }
   MapTransitionList const& transitions() const { return transitions_; }
 
  private:
   ElementsKind elements_kind_;
   MaybeHandle<JSObject> holder_;
-  Type* receiver_type_;
+  MapList receiver_maps_;
   MapTransitionList transitions_;
 };
 
-
 // This class encapsulates all information required to access a certain
 // object property, either on the object itself or on the prototype chain.
 class PropertyAccessInfo final {
  public:
   enum Kind { kInvalid, kNotFound, kDataConstant, kDataField };
 
-  static PropertyAccessInfo NotFound(Type* receiver_type,
+  static PropertyAccessInfo NotFound(MapList const& receiver_maps,
                                      MaybeHandle<JSObject> holder);
-  static PropertyAccessInfo DataConstant(Type* receiver_type,
+  static PropertyAccessInfo DataConstant(MapList const& receiver_maps,
                                          Handle<Object> constant,
                                          MaybeHandle<JSObject> holder);
   static PropertyAccessInfo DataField(
-      Type* receiver_type, FieldIndex field_index, Type* field_type,
+      MapList const& receiver_maps, FieldIndex field_index, Type* field_type,
       MaybeHandle<JSObject> holder = MaybeHandle<JSObject>(),
       MaybeHandle<Map> transition_map = MaybeHandle<Map>());
 
   PropertyAccessInfo();
 
+  bool Merge(PropertyAccessInfo const* that) WARN_UNUSED_RESULT;
+
   bool IsNotFound() const { return kind() == kNotFound; }
   bool IsDataConstant() const { return kind() == kDataConstant; }
   bool IsDataField() const { return kind() == kDataField; }
@@ -83,18 +83,19 @@ class PropertyAccessInfo final {
   Handle<Object> constant() const { return constant_; }
   FieldIndex field_index() const { return field_index_; }
   Type* field_type() const { return field_type_; }
-  Type* receiver_type() const { return receiver_type_; }
+  MapList const& receiver_maps() const { return receiver_maps_; }
 
  private:
-  PropertyAccessInfo(MaybeHandle<JSObject> holder, Type* receiver_type);
+  PropertyAccessInfo(MaybeHandle<JSObject> holder,
+                     MapList const& receiver_maps);
   PropertyAccessInfo(MaybeHandle<JSObject> holder, Handle<Object> constant,
-                     Type* receiver_type);
+                     MapList const& receiver_maps);
   PropertyAccessInfo(MaybeHandle<JSObject> holder,
                      MaybeHandle<Map> transition_map, FieldIndex field_index,
-                     Type* field_type, Type* receiver_type);
+                     Type* field_type, MapList const& receiver_maps);
 
   Kind kind_;
-  Type* receiver_type_;
+  MapList receiver_maps_;
   Handle<Object> constant_;
   MaybeHandle<Map> transition_map_;
   MaybeHandle<JSObject> holder_;