if (!maybe->ToObject(&writable)) return maybe;
backing_store = FixedArray::cast(writable);
}
- uint32_t length = static_cast<uint32_t>(backing_store->length());
+ uint32_t capacity = static_cast<uint32_t>(backing_store->length());
if (check_prototype &&
- (index >= length || backing_store->get(index)->IsTheHole())) {
+ (index >= capacity || backing_store->get(index)->IsTheHole())) {
bool found;
MaybeObject* result = SetElementWithCallbackSetterInPrototypes(index,
value,
if (found) return result;
}
- // Check whether there is extra space in fixed array.
- if (index < length) {
- if (HasFastSmiOnlyElements()) {
- if (!value->IsSmi()) {
- // If the value is a number, transition from smi-only to
- // FastDoubleElements.
- if (value->IsNumber()) {
- MaybeObject* maybe =
- SetFastDoubleElementsCapacityAndLength(length, length);
- if (maybe->IsFailure()) return maybe;
- FixedDoubleArray::cast(elements())->set(index, value->Number());
- return value;
- }
- // Value is not a number, transition to generic fast elements.
- MaybeObject* maybe_new_map = GetElementsTransitionMap(FAST_ELEMENTS);
- Map* new_map;
- if (!maybe_new_map->To<Map>(&new_map)) return maybe_new_map;
- set_map(new_map);
- }
+ uint32_t new_capacity = capacity;
+ // Check if the length property of this object needs to be updated.
+ uint32_t array_length = 0;
+ bool must_update_array_length = false;
+ if (IsJSArray()) {
+ CHECK(JSArray::cast(this)->length()->ToArrayIndex(&array_length));
+ if (index >= array_length) {
+ must_update_array_length = true;
+ array_length = index + 1;
}
- backing_store->set(index, value);
- if (IsJSArray()) {
- // Update the length of the array if needed.
- uint32_t array_length = 0;
- CHECK(JSArray::cast(this)->length()->ToArrayIndex(&array_length));
- if (index >= array_length) {
- JSArray::cast(this)->set_length(Smi::FromInt(index + 1));
+ }
+ // Check if the capacity of the backing store needs to be increased, or if
+ // a transition to slow elements is necessary.
+ if (index >= capacity) {
+ bool convert_to_slow = true;
+ if ((index - capacity) < kMaxGap) {
+ new_capacity = NewElementsCapacity(index + 1);
+ ASSERT(new_capacity > index);
+ if (!ShouldConvertToSlowElements(new_capacity)) {
+ convert_to_slow = false;
}
}
+ if (convert_to_slow) {
+ MaybeObject* result = NormalizeElements();
+ if (result->IsFailure()) return result;
+ return SetDictionaryElement(index, value, strict_mode, check_prototype);
+ }
+ }
+ // Convert to fast double elements if appropriate.
+ if (HasFastSmiOnlyElements() && !value->IsSmi() && value->IsNumber()) {
+ MaybeObject* maybe =
+ SetFastDoubleElementsCapacityAndLength(new_capacity, array_length);
+ if (maybe->IsFailure()) return maybe;
+ FixedDoubleArray::cast(elements())->set(index, value->Number());
return value;
}
-
- // Allow gap in fast case.
- if ((index - length) < kMaxGap) {
- // Try allocating extra space.
- int new_capacity = NewElementsCapacity(index + 1);
- if (!ShouldConvertToSlowElements(new_capacity)) {
- ASSERT(static_cast<uint32_t>(new_capacity) > index);
- Object* new_elements;
- SetFastElementsCapacityMode set_capacity_mode =
- value->IsSmi() && HasFastSmiOnlyElements()
- ? kAllowSmiOnlyElements
- : kDontAllowSmiOnlyElements;
- MaybeObject* maybe =
- SetFastElementsCapacityAndLength(new_capacity,
- index + 1,
- set_capacity_mode);
- if (!maybe->ToObject(&new_elements)) return maybe;
- FixedArray::cast(new_elements)->set(index, value);
- return value;
- }
+ // Change elements kind from SMI_ONLY to generic FAST if necessary.
+ if (HasFastSmiOnlyElements() && !value->IsSmi()) {
+ MaybeObject* maybe_new_map = GetElementsTransitionMap(FAST_ELEMENTS);
+ Map* new_map;
+ if (!maybe_new_map->To<Map>(&new_map)) return maybe_new_map;
+ set_map(new_map);
}
-
- // Otherwise default to slow case.
- MaybeObject* result = NormalizeElements();
- if (result->IsFailure()) return result;
- return SetDictionaryElement(index, value, strict_mode, check_prototype);
+ // Increase backing store capacity if that's been decided previously.
+ if (new_capacity != capacity) {
+ Object* new_elements;
+ SetFastElementsCapacityMode set_capacity_mode =
+ value->IsSmi() && HasFastSmiOnlyElements()
+ ? kAllowSmiOnlyElements
+ : kDontAllowSmiOnlyElements;
+ MaybeObject* maybe =
+ SetFastElementsCapacityAndLength(new_capacity,
+ array_length,
+ set_capacity_mode);
+ if (!maybe->ToObject(&new_elements)) return maybe;
+ FixedArray::cast(new_elements)->set(index, value);
+ return value;
+ }
+ // Finally, set the new element and length.
+ ASSERT(elements()->IsFixedArray());
+ backing_store->set(index, value);
+ if (must_update_array_length) {
+ JSArray::cast(this)->set_length(Smi::FromInt(array_length));
+ }
+ return value;
}