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| 1 // Copyright 2014 the V8 project authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #ifndef V8_LAYOUT_DESCRIPTOR_INL_H_ |
| 6 #define V8_LAYOUT_DESCRIPTOR_INL_H_ |
| 7 |
| 8 #include "src/layout-descriptor.h" |
| 9 |
| 10 namespace v8 { |
| 11 namespace internal { |
| 12 |
| 13 LayoutDescriptor* LayoutDescriptor::FromSmi(Smi* smi) { |
| 14 return LayoutDescriptor::cast(smi); |
| 15 } |
| 16 |
| 17 |
| 18 Handle<LayoutDescriptor> LayoutDescriptor::New(Isolate* isolate, int length) { |
| 19 if (length <= kSmiValueSize) { |
| 20 // The whole bit vector fits into a smi. |
| 21 return handle(LayoutDescriptor::FromSmi(Smi::FromInt(0)), isolate); |
| 22 } |
| 23 |
| 24 length = (length + kNumberOfBits - 1) / kNumberOfBits; |
| 25 DCHECK(length > 0); |
| 26 |
| 27 if (SmiValuesAre32Bits() && (length & 1)) { |
| 28 // On 64-bit systems if the length is odd then the half-word space would be |
| 29 // lost anyway (due to alignment and the fact that we are allocating |
| 30 // uint32-typed array), so we increase the length of allocated array |
| 31 // to utilize that "lost" space which could also help to avoid layout |
| 32 // descriptor reallocations. |
| 33 ++length; |
| 34 } |
| 35 return Handle<LayoutDescriptor>::cast( |
| 36 isolate->factory()->NewFixedTypedArray(length, kExternalUint32Array)); |
| 37 } |
| 38 |
| 39 |
| 40 bool LayoutDescriptor::InobjectUnboxedField(int inobject_properties, |
| 41 PropertyDetails details) { |
| 42 if (details.type() != FIELD || !details.representation().IsDouble()) { |
| 43 return false; |
| 44 } |
| 45 // We care only about in-object properties. |
| 46 return details.field_index() < inobject_properties; |
| 47 } |
| 48 |
| 49 |
| 50 LayoutDescriptor* LayoutDescriptor::FastPointerLayout() { |
| 51 return LayoutDescriptor::FromSmi(Smi::FromInt(0)); |
| 52 } |
| 53 |
| 54 |
| 55 bool LayoutDescriptor::GetIndexes(int field_index, int* layout_word_index, |
| 56 uint32_t* layout_mask) { |
| 57 if (static_cast<unsigned>(field_index) >= static_cast<unsigned>(capacity())) { |
| 58 return false; |
| 59 } |
| 60 |
| 61 *layout_word_index = field_index / kNumberOfBits; |
| 62 CHECK((!IsSmi() && (*layout_word_index < length())) || |
| 63 (IsSmi() && (*layout_word_index < 1))); |
| 64 |
| 65 int layout_bit_index = field_index % kNumberOfBits; |
| 66 *layout_mask = static_cast<uint32_t>(1) << layout_bit_index; |
| 67 return true; |
| 68 } |
| 69 |
| 70 |
| 71 LayoutDescriptor* LayoutDescriptor::SetTagged(int field_index, bool tagged) { |
| 72 int layout_word_index; |
| 73 uint32_t layout_mask; |
| 74 |
| 75 if (!GetIndexes(field_index, &layout_word_index, &layout_mask)) { |
| 76 CHECK(false); |
| 77 return this; |
| 78 } |
| 79 |
| 80 if (IsSlowLayout()) { |
| 81 uint32_t value = get_scalar(layout_word_index); |
| 82 if (tagged) { |
| 83 value &= ~layout_mask; |
| 84 } else { |
| 85 value |= layout_mask; |
| 86 } |
| 87 set(layout_word_index, value); |
| 88 return this; |
| 89 } else { |
| 90 uint32_t value = static_cast<uint32_t>(Smi::cast(this)->value()); |
| 91 if (tagged) { |
| 92 value &= ~layout_mask; |
| 93 } else { |
| 94 value |= layout_mask; |
| 95 } |
| 96 return LayoutDescriptor::FromSmi(Smi::FromInt(static_cast<int>(value))); |
| 97 } |
| 98 } |
| 99 |
| 100 |
| 101 bool LayoutDescriptor::IsTagged(int field_index) { |
| 102 if (IsFastPointerLayout()) return true; |
| 103 |
| 104 int layout_word_index; |
| 105 uint32_t layout_mask; |
| 106 |
| 107 if (!GetIndexes(field_index, &layout_word_index, &layout_mask)) { |
| 108 // All bits after Out of bounds queries |
| 109 return true; |
| 110 } |
| 111 |
| 112 if (IsSlowLayout()) { |
| 113 uint32_t value = get_scalar(layout_word_index); |
| 114 return (value & layout_mask) == 0; |
| 115 } else { |
| 116 uint32_t value = static_cast<uint32_t>(Smi::cast(this)->value()); |
| 117 return (value & layout_mask) == 0; |
| 118 } |
| 119 } |
| 120 |
| 121 |
| 122 bool LayoutDescriptor::IsFastPointerLayout() { |
| 123 return IsSmi() && (Smi::cast(this)->value() == 0); |
| 124 } |
| 125 |
| 126 |
| 127 bool LayoutDescriptor::IsSlowLayout() { return !IsSmi(); } |
| 128 |
| 129 |
| 130 int LayoutDescriptor::capacity() { |
| 131 return IsSlowLayout() ? (length() * kNumberOfBits) : kSmiValueSize; |
| 132 } |
| 133 |
| 134 |
| 135 LayoutDescriptor* LayoutDescriptor::cast_gc_safe(Object* object) { |
| 136 if (object->IsSmi()) { |
| 137 // Fast mode layout descriptor. |
| 138 return reinterpret_cast<LayoutDescriptor*>(object); |
| 139 } |
| 140 |
| 141 // This is a mixed descriptor which is a fixed typed array. |
| 142 MapWord map_word = reinterpret_cast<HeapObject*>(object)->map_word(); |
| 143 if (map_word.IsForwardingAddress()) { |
| 144 // Mark-compact has already moved layout descriptor. |
| 145 object = map_word.ToForwardingAddress(); |
| 146 } |
| 147 return LayoutDescriptor::cast(object); |
| 148 } |
| 149 |
| 150 |
| 151 // InobjectPropertiesHelper is a helper class for querying whether inobject |
| 152 // property at offset is Double or not. |
| 153 InobjectPropertiesHelper::InobjectPropertiesHelper(Map* map) |
| 154 : all_fields_tagged_(true), |
| 155 header_size_(0), |
| 156 inobject_properties_count_(0), |
| 157 layout_descriptor_(LayoutDescriptor::FastPointerLayout()) { |
| 158 if (!FLAG_unbox_double_fields) return; |
| 159 |
| 160 layout_descriptor_ = map->layout_descriptor_gc_safe(); |
| 161 if (layout_descriptor_->IsFastPointerLayout()) { |
| 162 return; |
| 163 } |
| 164 |
| 165 int inobject_properties = map->inobject_properties(); |
| 166 DCHECK(inobject_properties > 0); |
| 167 header_size_ = map->instance_size() - (inobject_properties * kPointerSize); |
| 168 DCHECK(header_size_ >= 0); |
| 169 |
| 170 all_fields_tagged_ = false; |
| 171 } |
| 172 |
| 173 |
| 174 bool InobjectPropertiesHelper::IsTagged(int offset_in_bytes) { |
| 175 DCHECK(IsAligned(offset_in_bytes, kPointerSize)); |
| 176 if (all_fields_tagged_) return true; |
| 177 // Object headers do not contain non-tagged fields. |
| 178 if (offset_in_bytes < header_size_) return true; |
| 179 int field_index = (offset_in_bytes - header_size_) / kPointerSize; |
| 180 |
| 181 return layout_descriptor_->IsTagged(field_index); |
| 182 } |
| 183 } |
| 184 } // namespace v8::internal |
| 185 |
| 186 #endif // V8_LAYOUT_DESCRIPTOR_INL_H_ |
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