[LookupIterator] Optimize the path that writes to fields.

Review URL: https://codereview.chromium.org/1717603002

Cr-Commit-Position: refs/heads/master@{#34149}

src/lookup.cc

@@ -517,18 +517,21 @@ void LookupIterator::WriteDataValue(Handle<Object> value) {
     Handle<JSObject> object = Handle<JSObject>::cast(holder);
     ElementsAccessor* accessor = object->GetElementsAccessor();
     accessor->Set(object, number_, *value);
+  } else if (holder->HasFastProperties()) {
+    if (property_details_.type() == v8::internal::DATA) {
+      JSObject::cast(*holder)->WriteToField(descriptor_number(),
+                                            property_details_, *value);
+    } else {
+      DCHECK_EQ(v8::internal::DATA_CONSTANT, property_details_.type());
+    }
   } else if (holder->IsJSGlobalObject()) {
     Handle<GlobalDictionary> property_dictionary =
         handle(JSObject::cast(*holder)->global_dictionary());
     PropertyCell::UpdateCell(property_dictionary, dictionary_entry(), value,
                              property_details_);
-  } else if (!holder->HasFastProperties()) {
+  } else {
     NameDictionary* property_dictionary = holder->property_dictionary();
     property_dictionary->ValueAtPut(dictionary_entry(), *value);
-  } else if (property_details_.type() == v8::internal::DATA) {
-    JSObject::cast(*holder)->WriteToField(descriptor_number(), *value);
-  } else {
-    DCHECK_EQ(v8::internal::DATA_CONSTANT, property_details_.type());
   }
 }
 

src/objects-inl.h

@@ -991,14 +991,14 @@ ElementsKind Object::OptimalElementsKind() {
 
 
 bool Object::FitsRepresentation(Representation representation) {
-  if (FLAG_track_fields && representation.IsNone()) {
-    return false;
-  } else if (FLAG_track_fields && representation.IsSmi()) {
+  if (FLAG_track_fields && representation.IsSmi()) {
     return IsSmi();
   } else if (FLAG_track_double_fields && representation.IsDouble()) {
     return IsMutableHeapNumber() || IsNumber();
   } else if (FLAG_track_heap_object_fields && representation.IsHeapObject()) {
     return IsHeapObject();
+  } else if (FLAG_track_fields && representation.IsNone()) {
+    return false;
   }
   return true;
 }
@@ -2088,15 +2088,10 @@ void JSObject::FastPropertyAtPut(FieldIndex index, Object* value) {
   }
 }
 
-
-void JSObject::WriteToField(int descriptor, Object* value) {
-  DisallowHeapAllocation no_gc;
-
-  DescriptorArray* desc = map()->instance_descriptors();
-  PropertyDetails details = desc->GetDetails(descriptor);
-
+void JSObject::WriteToField(int descriptor, PropertyDetails details,
+                            Object* value) {
   DCHECK(details.type() == DATA);
-
+  DisallowHeapAllocation no_gc;
   FieldIndex index = FieldIndex::ForDescriptor(map(), descriptor);
   if (details.representation().IsDouble()) {
     // Nothing more to be done.
@@ -2113,6 +2108,11 @@ void JSObject::WriteToField(int descriptor, Object* value) {
   }
 }
 
+void JSObject::WriteToField(int descriptor, Object* value) {
+  DescriptorArray* desc = map()->instance_descriptors();
+  PropertyDetails details = desc->GetDetails(descriptor);
+  WriteToField(descriptor, details, value);
+}
 
 int JSObject::GetInObjectPropertyOffset(int index) {
   return map()->GetInObjectPropertyOffset(index);

src/objects.h

@@ -2335,6 +2335,8 @@ class JSObject: public JSReceiver {
   inline void FastPropertyAtPut(FieldIndex index, Object* value);
   inline void RawFastPropertyAtPut(FieldIndex index, Object* value);
   inline void RawFastDoublePropertyAtPut(FieldIndex index, double value);
+  inline void WriteToField(int descriptor, PropertyDetails details,
+                           Object* value);
   inline void WriteToField(int descriptor, Object* value);
 
   // Access to in object properties.