[LookupIterator] Optimize the path that writes to fields.

src/objects-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 973 matching lines @@
 
 
 ElementsKind Object::OptimalElementsKind() {
   if (IsSmi()) return FAST_SMI_ELEMENTS;
   if (IsNumber()) return FAST_DOUBLE_ELEMENTS;
   return FAST_ELEMENTS;
 }
 
 
 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;
 }
 
 
 // static
 MaybeHandle<JSReceiver> Object::ToObject(Isolate* isolate,
                                          Handle<Object> object) {
   if (object->IsJSReceiver()) return Handle<JSReceiver>::cast(object);
   return ToObject(isolate, object, isolate->native_context());
@@ skipping 1069 matching lines @@
 
 void JSObject::FastPropertyAtPut(FieldIndex index, Object* value) {
   if (IsUnboxedDoubleField(index)) {
     DCHECK(value->IsMutableHeapNumber());
     RawFastDoublePropertyAtPut(index, HeapNumber::cast(value)->value());
   } else {
     RawFastPropertyAtPut(index, value);
   }
 }
 
-
-void JSObject::WriteToField(int descriptor, Object* value) {
+void JSObject::WriteToField(int descriptor, PropertyDetails details,
+                            Object* value) {
+  DCHECK(details.type() == DATA);
   DisallowHeapAllocation no_gc;
-
-  DescriptorArray* desc = map()->instance_descriptors();
-  PropertyDetails details = desc->GetDetails(descriptor);
-
-  DCHECK(details.type() == DATA);
-
   FieldIndex index = FieldIndex::ForDescriptor(map(), descriptor);
   if (details.representation().IsDouble()) {
     // Nothing more to be done.
     if (value->IsUninitialized()) return;
     if (IsUnboxedDoubleField(index)) {
       RawFastDoublePropertyAtPut(index, value->Number());
     } else {
       HeapNumber* box = HeapNumber::cast(RawFastPropertyAt(index));
       DCHECK(box->IsMutableHeapNumber());
       box->set_value(value->Number());
     }
   } else {
     RawFastPropertyAtPut(index, 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);
 }
 
 
 Object* JSObject::InObjectPropertyAt(int index) {
   int offset = GetInObjectPropertyOffset(index);
   return READ_FIELD(this, offset);
 }
@@ skipping 5547 matching lines @@
 #undef WRITE_INT64_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_INL_H_