| // Copyright 2014 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. |
| |
| #ifndef V8_LAYOUT_DESCRIPTOR_INL_H_ |
| #define V8_LAYOUT_DESCRIPTOR_INL_H_ |
| |
| #include "src/layout-descriptor.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| LayoutDescriptor* LayoutDescriptor::FromSmi(Smi* smi) { |
| return LayoutDescriptor::cast(smi); |
| } |
| |
| |
| Handle<LayoutDescriptor> LayoutDescriptor::New(Isolate* isolate, int length) { |
| if (length <= kSmiValueSize) { |
| // The whole bit vector fits into a smi. |
| return handle(LayoutDescriptor::FromSmi(Smi::kZero), isolate); |
| } |
| length = GetSlowModeBackingStoreLength(length); |
| return Handle<LayoutDescriptor>::cast(isolate->factory()->NewFixedTypedArray( |
| length, kExternalUint32Array, true)); |
| } |
| |
| |
| bool LayoutDescriptor::InobjectUnboxedField(int inobject_properties, |
| PropertyDetails details) { |
| if (details.type() != DATA || !details.representation().IsDouble()) { |
| return false; |
| } |
| // We care only about in-object properties. |
| return details.field_index() < inobject_properties; |
| } |
| |
| |
| LayoutDescriptor* LayoutDescriptor::FastPointerLayout() { |
| return LayoutDescriptor::FromSmi(Smi::kZero); |
| } |
| |
| |
| bool LayoutDescriptor::GetIndexes(int field_index, int* layout_word_index, |
| int* layout_bit_index) { |
| if (static_cast<unsigned>(field_index) >= static_cast<unsigned>(capacity())) { |
| return false; |
| } |
| |
| *layout_word_index = field_index / kNumberOfBits; |
| CHECK((!IsSmi() && (*layout_word_index < length())) || |
| (IsSmi() && (*layout_word_index < 1))); |
| |
| *layout_bit_index = field_index % kNumberOfBits; |
| return true; |
| } |
| |
| |
| LayoutDescriptor* LayoutDescriptor::SetRawData(int field_index) { |
| return SetTagged(field_index, false); |
| } |
| |
| |
| LayoutDescriptor* LayoutDescriptor::SetTagged(int field_index, bool tagged) { |
| int layout_word_index = 0; |
| int layout_bit_index = 0; |
| |
| if (!GetIndexes(field_index, &layout_word_index, &layout_bit_index)) { |
| CHECK(false); |
| return this; |
| } |
| uint32_t layout_mask = static_cast<uint32_t>(1) << layout_bit_index; |
| |
| if (IsSlowLayout()) { |
| uint32_t value = get_scalar(layout_word_index); |
| if (tagged) { |
| value &= ~layout_mask; |
| } else { |
| value |= layout_mask; |
| } |
| set(layout_word_index, value); |
| return this; |
| } else { |
| uint32_t value = static_cast<uint32_t>(Smi::cast(this)->value()); |
| if (tagged) { |
| value &= ~layout_mask; |
| } else { |
| value |= layout_mask; |
| } |
| return LayoutDescriptor::FromSmi(Smi::FromInt(static_cast<int>(value))); |
| } |
| } |
| |
| |
| bool LayoutDescriptor::IsTagged(int field_index) { |
| if (IsFastPointerLayout()) return true; |
| |
| int layout_word_index; |
| int layout_bit_index; |
| |
| if (!GetIndexes(field_index, &layout_word_index, &layout_bit_index)) { |
| // All bits after Out of bounds queries |
| return true; |
| } |
| uint32_t layout_mask = static_cast<uint32_t>(1) << layout_bit_index; |
| |
| if (IsSlowLayout()) { |
| uint32_t value = get_scalar(layout_word_index); |
| return (value & layout_mask) == 0; |
| } else { |
| uint32_t value = static_cast<uint32_t>(Smi::cast(this)->value()); |
| return (value & layout_mask) == 0; |
| } |
| } |
| |
| |
| bool LayoutDescriptor::IsFastPointerLayout() { |
| return this == FastPointerLayout(); |
| } |
| |
| |
| bool LayoutDescriptor::IsFastPointerLayout(Object* layout_descriptor) { |
| return layout_descriptor == FastPointerLayout(); |
| } |
| |
| |
| bool LayoutDescriptor::IsSlowLayout() { return !IsSmi(); } |
| |
| |
| int LayoutDescriptor::capacity() { |
| return IsSlowLayout() ? (length() * kNumberOfBits) : kSmiValueSize; |
| } |
| |
| |
| LayoutDescriptor* LayoutDescriptor::cast_gc_safe(Object* object) { |
| if (object->IsSmi()) { |
| // Fast mode layout descriptor. |
| return reinterpret_cast<LayoutDescriptor*>(object); |
| } |
| |
| // This is a mixed descriptor which is a fixed typed array. |
| MapWord map_word = reinterpret_cast<HeapObject*>(object)->map_word(); |
| if (map_word.IsForwardingAddress()) { |
| // Mark-compact has already moved layout descriptor. |
| object = map_word.ToForwardingAddress(); |
| } |
| return LayoutDescriptor::cast(object); |
| } |
| |
| |
| int LayoutDescriptor::GetSlowModeBackingStoreLength(int length) { |
| length = (length + kNumberOfBits - 1) / kNumberOfBits; |
| DCHECK_LT(0, length); |
| |
| if (SmiValuesAre32Bits() && (length & 1)) { |
| // On 64-bit systems if the length is odd then the half-word space would be |
| // lost anyway (due to alignment and the fact that we are allocating |
| // uint32-typed array), so we increase the length of allocated array |
| // to utilize that "lost" space which could also help to avoid layout |
| // descriptor reallocations. |
| ++length; |
| } |
| return length; |
| } |
| |
| |
| int LayoutDescriptor::CalculateCapacity(Map* map, DescriptorArray* descriptors, |
| int num_descriptors) { |
| int inobject_properties = map->GetInObjectProperties(); |
| if (inobject_properties == 0) return 0; |
| |
| DCHECK_LE(num_descriptors, descriptors->number_of_descriptors()); |
| |
| int layout_descriptor_length; |
| const int kMaxWordsPerField = kDoubleSize / kPointerSize; |
| |
| if (num_descriptors <= kSmiValueSize / kMaxWordsPerField) { |
| // Even in the "worst" case (all fields are doubles) it would fit into |
| // a Smi, so no need to calculate length. |
| layout_descriptor_length = kSmiValueSize; |
| |
| } else { |
| layout_descriptor_length = 0; |
| |
| for (int i = 0; i < num_descriptors; i++) { |
| PropertyDetails details = descriptors->GetDetails(i); |
| if (!InobjectUnboxedField(inobject_properties, details)) continue; |
| int field_index = details.field_index(); |
| int field_width_in_words = details.field_width_in_words(); |
| layout_descriptor_length = |
| Max(layout_descriptor_length, field_index + field_width_in_words); |
| } |
| } |
| layout_descriptor_length = Min(layout_descriptor_length, inobject_properties); |
| return layout_descriptor_length; |
| } |
| |
| |
| LayoutDescriptor* LayoutDescriptor::Initialize( |
| LayoutDescriptor* layout_descriptor, Map* map, DescriptorArray* descriptors, |
| int num_descriptors) { |
| DisallowHeapAllocation no_allocation; |
| int inobject_properties = map->GetInObjectProperties(); |
| |
| for (int i = 0; i < num_descriptors; i++) { |
| PropertyDetails details = descriptors->GetDetails(i); |
| if (!InobjectUnboxedField(inobject_properties, details)) { |
| DCHECK(details.location() != kField || |
| layout_descriptor->IsTagged(details.field_index())); |
| continue; |
| } |
| int field_index = details.field_index(); |
| layout_descriptor = layout_descriptor->SetRawData(field_index); |
| if (details.field_width_in_words() > 1) { |
| layout_descriptor = layout_descriptor->SetRawData(field_index + 1); |
| } |
| } |
| return layout_descriptor; |
| } |
| |
| |
| // LayoutDescriptorHelper is a helper class for querying whether inobject |
| // property at offset is Double or not. |
| LayoutDescriptorHelper::LayoutDescriptorHelper(Map* map) |
| : all_fields_tagged_(true), |
| header_size_(0), |
| layout_descriptor_(LayoutDescriptor::FastPointerLayout()) { |
| if (!FLAG_unbox_double_fields) return; |
| |
| layout_descriptor_ = map->layout_descriptor_gc_safe(); |
| if (layout_descriptor_->IsFastPointerLayout()) { |
| return; |
| } |
| |
| int inobject_properties = map->GetInObjectProperties(); |
| DCHECK(inobject_properties > 0); |
| header_size_ = map->instance_size() - (inobject_properties * kPointerSize); |
| DCHECK(header_size_ >= 0); |
| |
| all_fields_tagged_ = false; |
| } |
| |
| |
| bool LayoutDescriptorHelper::IsTagged(int offset_in_bytes) { |
| DCHECK(IsAligned(offset_in_bytes, kPointerSize)); |
| if (all_fields_tagged_) return true; |
| // Object headers do not contain non-tagged fields. |
| if (offset_in_bytes < header_size_) return true; |
| int field_index = (offset_in_bytes - header_size_) / kPointerSize; |
| |
| return layout_descriptor_->IsTagged(field_index); |
| } |
| } // namespace internal |
| } // namespace v8 |
| |
| #endif // V8_LAYOUT_DESCRIPTOR_INL_H_ |