Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 1 | // Copyright 2012 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 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 5 | #include "src/transitions.h" |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 6 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 7 | #include "src/objects-inl.h" |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 8 | #include "src/transitions-inl.h" |
| 9 | #include "src/utils.h" |
| 10 | |
| 11 | namespace v8 { |
| 12 | namespace internal { |
| 13 | |
| 14 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 15 | // static |
| 16 | void TransitionArray::Insert(Handle<Map> map, Handle<Name> name, |
| 17 | Handle<Map> target, SimpleTransitionFlag flag) { |
| 18 | Isolate* isolate = map->GetIsolate(); |
| 19 | target->SetBackPointer(*map); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 20 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 21 | // If the map doesn't have any transitions at all yet, install the new one. |
| 22 | if (CanStoreSimpleTransition(map->raw_transitions())) { |
| 23 | if (flag == SIMPLE_PROPERTY_TRANSITION) { |
| 24 | Handle<WeakCell> cell = Map::WeakCellForMap(target); |
| 25 | ReplaceTransitions(map, *cell); |
| 26 | return; |
| 27 | } |
| 28 | // If the flag requires a full TransitionArray, allocate one. |
| 29 | Handle<TransitionArray> result = Allocate(isolate, 0, 1); |
| 30 | ReplaceTransitions(map, *result); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 31 | } |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 32 | |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 33 | bool is_special_transition = flag == SPECIAL_TRANSITION; |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 34 | // If the map has a simple transition, check if it should be overwritten. |
| 35 | if (IsSimpleTransition(map->raw_transitions())) { |
| 36 | Map* old_target = GetSimpleTransition(map->raw_transitions()); |
| 37 | Name* key = GetSimpleTransitionKey(old_target); |
| 38 | PropertyDetails old_details = GetSimpleTargetDetails(old_target); |
| 39 | PropertyDetails new_details = is_special_transition |
| 40 | ? PropertyDetails::Empty() |
| 41 | : GetTargetDetails(*name, *target); |
| 42 | if (flag == SIMPLE_PROPERTY_TRANSITION && key->Equals(*name) && |
| 43 | old_details.kind() == new_details.kind() && |
| 44 | old_details.attributes() == new_details.attributes()) { |
| 45 | Handle<WeakCell> cell = Map::WeakCellForMap(target); |
| 46 | ReplaceTransitions(map, *cell); |
| 47 | return; |
| 48 | } |
| 49 | // Otherwise allocate a full TransitionArray with slack for a new entry. |
| 50 | Handle<TransitionArray> result = Allocate(isolate, 1, 1); |
| 51 | // Re-read existing data; the allocation might have caused it to be cleared. |
| 52 | if (IsSimpleTransition(map->raw_transitions())) { |
| 53 | old_target = GetSimpleTransition(map->raw_transitions()); |
| 54 | result->Set(0, GetSimpleTransitionKey(old_target), old_target); |
| 55 | } else { |
| 56 | result->SetNumberOfTransitions(0); |
| 57 | } |
| 58 | ReplaceTransitions(map, *result); |
| 59 | } |
| 60 | |
| 61 | // At this point, we know that the map has a full TransitionArray. |
| 62 | DCHECK(IsFullTransitionArray(map->raw_transitions())); |
| 63 | |
| 64 | int number_of_transitions = 0; |
| 65 | int new_nof = 0; |
| 66 | int insertion_index = kNotFound; |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 67 | DCHECK_EQ(is_special_transition, IsSpecialTransition(*name)); |
| 68 | PropertyDetails details = is_special_transition |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 69 | ? PropertyDetails::Empty() |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 70 | : GetTargetDetails(*name, *target); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 71 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 72 | { |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 73 | DisallowHeapAllocation no_gc; |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 74 | TransitionArray* array = TransitionArray::cast(map->raw_transitions()); |
| 75 | number_of_transitions = array->number_of_transitions(); |
| 76 | new_nof = number_of_transitions; |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 77 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 78 | int index = |
| 79 | is_special_transition |
| 80 | ? array->SearchSpecial(Symbol::cast(*name), &insertion_index) |
| 81 | : array->Search(details.kind(), *name, details.attributes(), |
| 82 | &insertion_index); |
| 83 | // If an existing entry was found, overwrite it and return. |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 84 | if (index != kNotFound) { |
| 85 | array->SetTarget(index, *target); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 86 | return; |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 87 | } |
| 88 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 89 | ++new_nof; |
| 90 | CHECK(new_nof <= kMaxNumberOfTransitions); |
| 91 | DCHECK(insertion_index >= 0 && insertion_index <= number_of_transitions); |
| 92 | |
| 93 | // If there is enough capacity, insert new entry into the existing array. |
| 94 | if (new_nof <= Capacity(array)) { |
| 95 | array->SetNumberOfTransitions(new_nof); |
| 96 | for (index = number_of_transitions; index > insertion_index; --index) { |
| 97 | array->SetKey(index, array->GetKey(index - 1)); |
| 98 | array->SetTarget(index, array->GetTarget(index - 1)); |
| 99 | } |
| 100 | array->SetKey(index, *name); |
| 101 | array->SetTarget(index, *target); |
| 102 | SLOW_DCHECK(array->IsSortedNoDuplicates()); |
| 103 | return; |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 104 | } |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 105 | } |
| 106 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 107 | // We're gonna need a bigger TransitionArray. |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 108 | Handle<TransitionArray> result = Allocate( |
| 109 | map->GetIsolate(), new_nof, |
| 110 | Map::SlackForArraySize(number_of_transitions, kMaxNumberOfTransitions)); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 111 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 112 | // The map's transition array may have shrunk during the allocation above as |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 113 | // it was weakly traversed, though it is guaranteed not to disappear. Trim the |
| 114 | // result copy if needed, and recompute variables. |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 115 | DCHECK(IsFullTransitionArray(map->raw_transitions())); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 116 | DisallowHeapAllocation no_gc; |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 117 | TransitionArray* array = TransitionArray::cast(map->raw_transitions()); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 118 | if (array->number_of_transitions() != number_of_transitions) { |
| 119 | DCHECK(array->number_of_transitions() < number_of_transitions); |
| 120 | |
| 121 | number_of_transitions = array->number_of_transitions(); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 122 | new_nof = number_of_transitions; |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 123 | |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 124 | insertion_index = kNotFound; |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 125 | int index = |
| 126 | is_special_transition |
| 127 | ? array->SearchSpecial(Symbol::cast(*name), &insertion_index) |
| 128 | : array->Search(details.kind(), *name, details.attributes(), |
| 129 | &insertion_index); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 130 | if (index == kNotFound) { |
| 131 | ++new_nof; |
| 132 | } else { |
| 133 | insertion_index = index; |
| 134 | } |
| 135 | DCHECK(insertion_index >= 0 && insertion_index <= number_of_transitions); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 136 | |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 137 | result->Shrink(ToKeyIndex(new_nof)); |
| 138 | result->SetNumberOfTransitions(new_nof); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 139 | } |
| 140 | |
| 141 | if (array->HasPrototypeTransitions()) { |
| 142 | result->SetPrototypeTransitions(array->GetPrototypeTransitions()); |
| 143 | } |
| 144 | |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 145 | DCHECK_NE(kNotFound, insertion_index); |
| 146 | for (int i = 0; i < insertion_index; ++i) { |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 147 | result->Set(i, array->GetKey(i), array->GetTarget(i)); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 148 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 149 | result->Set(insertion_index, *name, *target); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 150 | for (int i = insertion_index; i < number_of_transitions; ++i) { |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 151 | result->Set(i + 1, array->GetKey(i), array->GetTarget(i)); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 152 | } |
| 153 | |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 154 | SLOW_DCHECK(result->IsSortedNoDuplicates()); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 155 | ReplaceTransitions(map, *result); |
Ben Murdoch | b8a8cc1 | 2014-11-26 15:28:44 +0000 | [diff] [blame] | 156 | } |
| 157 | |
| 158 | |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 159 | // static |
| 160 | Map* TransitionArray::SearchTransition(Map* map, PropertyKind kind, Name* name, |
| 161 | PropertyAttributes attributes) { |
| 162 | Object* raw_transitions = map->raw_transitions(); |
| 163 | if (IsSimpleTransition(raw_transitions)) { |
| 164 | Map* target = GetSimpleTransition(raw_transitions); |
| 165 | Name* key = GetSimpleTransitionKey(target); |
| 166 | if (!key->Equals(name)) return NULL; |
| 167 | PropertyDetails details = GetSimpleTargetDetails(target); |
| 168 | if (details.attributes() != attributes) return NULL; |
| 169 | if (details.kind() != kind) return NULL; |
| 170 | return target; |
| 171 | } |
| 172 | if (IsFullTransitionArray(raw_transitions)) { |
| 173 | TransitionArray* transitions = TransitionArray::cast(raw_transitions); |
| 174 | int transition = transitions->Search(kind, name, attributes); |
| 175 | if (transition == kNotFound) return NULL; |
| 176 | return transitions->GetTarget(transition); |
| 177 | } |
| 178 | return NULL; |
| 179 | } |
| 180 | |
| 181 | |
| 182 | // static |
| 183 | Map* TransitionArray::SearchSpecial(Map* map, Symbol* name) { |
| 184 | Object* raw_transitions = map->raw_transitions(); |
| 185 | if (IsFullTransitionArray(raw_transitions)) { |
| 186 | TransitionArray* transitions = TransitionArray::cast(raw_transitions); |
| 187 | int transition = transitions->SearchSpecial(name); |
| 188 | if (transition == kNotFound) return NULL; |
| 189 | return transitions->GetTarget(transition); |
| 190 | } |
| 191 | return NULL; |
| 192 | } |
| 193 | |
| 194 | |
| 195 | // static |
| 196 | Handle<Map> TransitionArray::FindTransitionToField(Handle<Map> map, |
| 197 | Handle<Name> name) { |
| 198 | DisallowHeapAllocation no_gc; |
| 199 | Map* target = SearchTransition(*map, kData, *name, NONE); |
| 200 | if (target == NULL) return Handle<Map>::null(); |
| 201 | PropertyDetails details = target->GetLastDescriptorDetails(); |
| 202 | DCHECK_EQ(NONE, details.attributes()); |
| 203 | if (details.type() != DATA) return Handle<Map>::null(); |
| 204 | return Handle<Map>(target); |
| 205 | } |
| 206 | |
| 207 | |
| 208 | // static |
| 209 | Handle<String> TransitionArray::ExpectedTransitionKey(Handle<Map> map) { |
| 210 | DisallowHeapAllocation no_gc; |
| 211 | Object* raw_transition = map->raw_transitions(); |
| 212 | if (!IsSimpleTransition(raw_transition)) return Handle<String>::null(); |
| 213 | Map* target = GetSimpleTransition(raw_transition); |
| 214 | PropertyDetails details = GetSimpleTargetDetails(target); |
| 215 | if (details.type() != DATA) return Handle<String>::null(); |
| 216 | if (details.attributes() != NONE) return Handle<String>::null(); |
| 217 | Name* name = GetSimpleTransitionKey(target); |
| 218 | if (!name->IsString()) return Handle<String>::null(); |
| 219 | return Handle<String>(String::cast(name)); |
| 220 | } |
| 221 | |
| 222 | |
| 223 | // static |
| 224 | bool TransitionArray::CanHaveMoreTransitions(Handle<Map> map) { |
| 225 | if (map->is_dictionary_map()) return false; |
| 226 | Object* raw_transitions = map->raw_transitions(); |
| 227 | if (IsFullTransitionArray(raw_transitions)) { |
| 228 | TransitionArray* transitions = TransitionArray::cast(raw_transitions); |
| 229 | return transitions->number_of_transitions() < kMaxNumberOfTransitions; |
| 230 | } |
| 231 | return true; |
| 232 | } |
| 233 | |
| 234 | |
| 235 | // static |
| 236 | bool TransitionArray::CompactPrototypeTransitionArray(FixedArray* array) { |
| 237 | const int header = kProtoTransitionHeaderSize; |
| 238 | int number_of_transitions = NumberOfPrototypeTransitions(array); |
| 239 | if (number_of_transitions == 0) { |
| 240 | // Empty array cannot be compacted. |
| 241 | return false; |
| 242 | } |
| 243 | int new_number_of_transitions = 0; |
| 244 | for (int i = 0; i < number_of_transitions; i++) { |
| 245 | Object* cell = array->get(header + i); |
| 246 | if (!WeakCell::cast(cell)->cleared()) { |
| 247 | if (new_number_of_transitions != i) { |
| 248 | array->set(header + new_number_of_transitions, cell); |
| 249 | } |
| 250 | new_number_of_transitions++; |
| 251 | } |
| 252 | } |
| 253 | // Fill slots that became free with undefined value. |
| 254 | for (int i = new_number_of_transitions; i < number_of_transitions; i++) { |
| 255 | array->set_undefined(header + i); |
| 256 | } |
| 257 | if (number_of_transitions != new_number_of_transitions) { |
| 258 | SetNumberOfPrototypeTransitions(array, new_number_of_transitions); |
| 259 | } |
| 260 | return new_number_of_transitions < number_of_transitions; |
| 261 | } |
| 262 | |
| 263 | |
| 264 | // static |
| 265 | Handle<FixedArray> TransitionArray::GrowPrototypeTransitionArray( |
| 266 | Handle<FixedArray> array, int new_capacity, Isolate* isolate) { |
| 267 | // Grow array by factor 2 up to MaxCachedPrototypeTransitions. |
| 268 | int capacity = array->length() - kProtoTransitionHeaderSize; |
| 269 | new_capacity = Min(kMaxCachedPrototypeTransitions, new_capacity); |
| 270 | DCHECK_GT(new_capacity, capacity); |
| 271 | int grow_by = new_capacity - capacity; |
| 272 | array = isolate->factory()->CopyFixedArrayAndGrow(array, grow_by, TENURED); |
| 273 | if (capacity < 0) { |
| 274 | // There was no prototype transitions array before, so the size |
| 275 | // couldn't be copied. Initialize it explicitly. |
| 276 | SetNumberOfPrototypeTransitions(*array, 0); |
| 277 | } |
| 278 | return array; |
| 279 | } |
| 280 | |
| 281 | |
| 282 | // static |
| 283 | int TransitionArray::NumberOfPrototypeTransitionsForTest(Map* map) { |
| 284 | FixedArray* transitions = GetPrototypeTransitions(map); |
| 285 | CompactPrototypeTransitionArray(transitions); |
| 286 | return TransitionArray::NumberOfPrototypeTransitions(transitions); |
| 287 | } |
| 288 | |
| 289 | |
| 290 | // static |
| 291 | void TransitionArray::PutPrototypeTransition(Handle<Map> map, |
| 292 | Handle<Object> prototype, |
| 293 | Handle<Map> target_map) { |
| 294 | DCHECK(HeapObject::cast(*prototype)->map()->IsMap()); |
| 295 | // Don't cache prototype transition if this map is either shared, or a map of |
| 296 | // a prototype. |
| 297 | if (map->is_prototype_map()) return; |
| 298 | if (map->is_dictionary_map() || !FLAG_cache_prototype_transitions) return; |
| 299 | |
| 300 | const int header = kProtoTransitionHeaderSize; |
| 301 | |
| 302 | Handle<WeakCell> target_cell = Map::WeakCellForMap(target_map); |
| 303 | |
| 304 | Handle<FixedArray> cache(GetPrototypeTransitions(*map)); |
| 305 | int capacity = cache->length() - header; |
| 306 | int transitions = NumberOfPrototypeTransitions(*cache) + 1; |
| 307 | |
| 308 | if (transitions > capacity) { |
| 309 | // Grow the array if compacting it doesn't free space. |
| 310 | if (!CompactPrototypeTransitionArray(*cache)) { |
| 311 | if (capacity == kMaxCachedPrototypeTransitions) return; |
| 312 | cache = GrowPrototypeTransitionArray(cache, 2 * transitions, |
| 313 | map->GetIsolate()); |
| 314 | SetPrototypeTransitions(map, cache); |
| 315 | } |
| 316 | } |
| 317 | |
| 318 | // Reload number of transitions as they might have been compacted. |
| 319 | int last = NumberOfPrototypeTransitions(*cache); |
| 320 | int entry = header + last; |
| 321 | |
| 322 | cache->set(entry, *target_cell); |
| 323 | SetNumberOfPrototypeTransitions(*cache, last + 1); |
| 324 | } |
| 325 | |
| 326 | |
| 327 | // static |
| 328 | Handle<Map> TransitionArray::GetPrototypeTransition(Handle<Map> map, |
| 329 | Handle<Object> prototype) { |
| 330 | DisallowHeapAllocation no_gc; |
| 331 | FixedArray* cache = GetPrototypeTransitions(*map); |
| 332 | int number_of_transitions = NumberOfPrototypeTransitions(cache); |
| 333 | for (int i = 0; i < number_of_transitions; i++) { |
| 334 | WeakCell* target_cell = |
| 335 | WeakCell::cast(cache->get(kProtoTransitionHeaderSize + i)); |
| 336 | if (!target_cell->cleared() && |
| 337 | Map::cast(target_cell->value())->prototype() == *prototype) { |
| 338 | return handle(Map::cast(target_cell->value())); |
| 339 | } |
| 340 | } |
| 341 | return Handle<Map>(); |
| 342 | } |
| 343 | |
| 344 | |
| 345 | // static |
| 346 | FixedArray* TransitionArray::GetPrototypeTransitions(Map* map) { |
| 347 | Object* raw_transitions = map->raw_transitions(); |
| 348 | Heap* heap = map->GetHeap(); |
| 349 | if (!IsFullTransitionArray(raw_transitions)) { |
| 350 | return heap->empty_fixed_array(); |
| 351 | } |
| 352 | TransitionArray* transitions = TransitionArray::cast(raw_transitions); |
| 353 | if (!transitions->HasPrototypeTransitions()) { |
| 354 | return heap->empty_fixed_array(); |
| 355 | } |
| 356 | return transitions->GetPrototypeTransitions(); |
| 357 | } |
| 358 | |
| 359 | |
| 360 | // static |
| 361 | void TransitionArray::SetNumberOfPrototypeTransitions( |
| 362 | FixedArray* proto_transitions, int value) { |
| 363 | DCHECK(proto_transitions->length() != 0); |
| 364 | proto_transitions->set(kProtoTransitionNumberOfEntriesOffset, |
| 365 | Smi::FromInt(value)); |
| 366 | } |
| 367 | |
| 368 | |
| 369 | // static |
| 370 | int TransitionArray::NumberOfTransitions(Object* raw_transitions) { |
| 371 | if (CanStoreSimpleTransition(raw_transitions)) return 0; |
| 372 | if (IsSimpleTransition(raw_transitions)) return 1; |
| 373 | // Prototype maps don't have transitions. |
| 374 | if (raw_transitions->IsPrototypeInfo()) return 0; |
| 375 | DCHECK(IsFullTransitionArray(raw_transitions)); |
| 376 | return TransitionArray::cast(raw_transitions)->number_of_transitions(); |
| 377 | } |
| 378 | |
| 379 | |
| 380 | // static |
| 381 | int TransitionArray::Capacity(Object* raw_transitions) { |
| 382 | if (!IsFullTransitionArray(raw_transitions)) return 1; |
| 383 | TransitionArray* t = TransitionArray::cast(raw_transitions); |
| 384 | if (t->length() <= kFirstIndex) return 0; |
| 385 | return (t->length() - kFirstIndex) / kTransitionSize; |
| 386 | } |
| 387 | |
| 388 | |
| 389 | // Private static helper functions. |
| 390 | |
| 391 | Handle<TransitionArray> TransitionArray::Allocate(Isolate* isolate, |
| 392 | int number_of_transitions, |
| 393 | int slack) { |
| 394 | Handle<FixedArray> array = isolate->factory()->NewTransitionArray( |
| 395 | LengthFor(number_of_transitions + slack)); |
| 396 | array->set(kNextLinkIndex, isolate->heap()->undefined_value()); |
| 397 | array->set(kPrototypeTransitionsIndex, Smi::FromInt(0)); |
| 398 | array->set(kTransitionLengthIndex, Smi::FromInt(number_of_transitions)); |
| 399 | return Handle<TransitionArray>::cast(array); |
| 400 | } |
| 401 | |
| 402 | |
| 403 | // static |
| 404 | void TransitionArray::ZapTransitionArray(TransitionArray* transitions) { |
| 405 | // Do not zap the next link that is used by GC. |
| 406 | STATIC_ASSERT(kNextLinkIndex + 1 == kPrototypeTransitionsIndex); |
| 407 | MemsetPointer(transitions->data_start() + kPrototypeTransitionsIndex, |
| 408 | transitions->GetHeap()->the_hole_value(), |
| 409 | transitions->length() - kPrototypeTransitionsIndex); |
| 410 | transitions->SetNumberOfTransitions(0); |
| 411 | } |
| 412 | |
| 413 | |
| 414 | void TransitionArray::ReplaceTransitions(Handle<Map> map, |
| 415 | Object* new_transitions) { |
| 416 | Object* raw_transitions = map->raw_transitions(); |
| 417 | if (IsFullTransitionArray(raw_transitions)) { |
| 418 | TransitionArray* old_transitions = TransitionArray::cast(raw_transitions); |
| 419 | #ifdef DEBUG |
| 420 | CheckNewTransitionsAreConsistent(map, old_transitions, new_transitions); |
| 421 | DCHECK(old_transitions != new_transitions); |
| 422 | #endif |
| 423 | // Transition arrays are not shared. When one is replaced, it should not |
| 424 | // keep referenced objects alive, so we zap it. |
| 425 | // When there is another reference to the array somewhere (e.g. a handle), |
| 426 | // not zapping turns from a waste of memory into a source of crashes. |
| 427 | ZapTransitionArray(old_transitions); |
| 428 | } |
| 429 | map->set_raw_transitions(new_transitions); |
| 430 | } |
| 431 | |
| 432 | |
| 433 | void TransitionArray::SetPrototypeTransitions( |
| 434 | Handle<Map> map, Handle<FixedArray> proto_transitions) { |
| 435 | EnsureHasFullTransitionArray(map); |
| 436 | TransitionArray* transitions = TransitionArray::cast(map->raw_transitions()); |
| 437 | transitions->SetPrototypeTransitions(*proto_transitions); |
| 438 | } |
| 439 | |
| 440 | |
| 441 | void TransitionArray::EnsureHasFullTransitionArray(Handle<Map> map) { |
| 442 | Object* raw_transitions = map->raw_transitions(); |
| 443 | if (IsFullTransitionArray(raw_transitions)) return; |
| 444 | int nof = IsSimpleTransition(raw_transitions) ? 1 : 0; |
| 445 | Handle<TransitionArray> result = Allocate(map->GetIsolate(), nof); |
| 446 | DisallowHeapAllocation no_gc; |
| 447 | // Reload pointer after the allocation that just happened. |
| 448 | raw_transitions = map->raw_transitions(); |
| 449 | int new_nof = IsSimpleTransition(raw_transitions) ? 1 : 0; |
| 450 | if (new_nof != nof) { |
| 451 | DCHECK(new_nof == 0); |
| 452 | result->Shrink(ToKeyIndex(0)); |
| 453 | result->SetNumberOfTransitions(0); |
| 454 | } else if (nof == 1) { |
| 455 | Map* target = GetSimpleTransition(raw_transitions); |
| 456 | Name* key = GetSimpleTransitionKey(target); |
| 457 | result->Set(0, key, target); |
| 458 | } |
| 459 | ReplaceTransitions(map, *result); |
| 460 | } |
| 461 | |
| 462 | |
| 463 | void TransitionArray::TraverseTransitionTreeInternal(Map* map, |
| 464 | TraverseCallback callback, |
| 465 | void* data) { |
| 466 | Object* raw_transitions = map->raw_transitions(); |
| 467 | if (IsFullTransitionArray(raw_transitions)) { |
| 468 | TransitionArray* transitions = TransitionArray::cast(raw_transitions); |
| 469 | if (transitions->HasPrototypeTransitions()) { |
| 470 | FixedArray* proto_trans = transitions->GetPrototypeTransitions(); |
| 471 | for (int i = 0; i < NumberOfPrototypeTransitions(proto_trans); ++i) { |
| 472 | int index = TransitionArray::kProtoTransitionHeaderSize + i; |
| 473 | WeakCell* cell = WeakCell::cast(proto_trans->get(index)); |
| 474 | if (!cell->cleared()) { |
| 475 | TraverseTransitionTreeInternal(Map::cast(cell->value()), callback, |
| 476 | data); |
| 477 | } |
| 478 | } |
| 479 | } |
| 480 | for (int i = 0; i < transitions->number_of_transitions(); ++i) { |
| 481 | TraverseTransitionTreeInternal(transitions->GetTarget(i), callback, data); |
| 482 | } |
| 483 | } else if (IsSimpleTransition(raw_transitions)) { |
| 484 | TraverseTransitionTreeInternal(GetSimpleTransition(raw_transitions), |
| 485 | callback, data); |
| 486 | } |
| 487 | callback(map, data); |
| 488 | } |
| 489 | |
| 490 | |
| 491 | #ifdef DEBUG |
| 492 | void TransitionArray::CheckNewTransitionsAreConsistent( |
| 493 | Handle<Map> map, TransitionArray* old_transitions, Object* transitions) { |
| 494 | // This function only handles full transition arrays. |
| 495 | DCHECK(IsFullTransitionArray(transitions)); |
| 496 | TransitionArray* new_transitions = TransitionArray::cast(transitions); |
| 497 | for (int i = 0; i < old_transitions->number_of_transitions(); i++) { |
| 498 | Map* target = old_transitions->GetTarget(i); |
| 499 | if (target->instance_descriptors() == map->instance_descriptors()) { |
| 500 | Name* key = old_transitions->GetKey(i); |
| 501 | int new_target_index; |
| 502 | if (TransitionArray::IsSpecialTransition(key)) { |
| 503 | new_target_index = new_transitions->SearchSpecial(Symbol::cast(key)); |
| 504 | } else { |
| 505 | PropertyDetails details = |
| 506 | TransitionArray::GetTargetDetails(key, target); |
| 507 | new_target_index = |
| 508 | new_transitions->Search(details.kind(), key, details.attributes()); |
| 509 | } |
| 510 | DCHECK_NE(TransitionArray::kNotFound, new_target_index); |
| 511 | DCHECK_EQ(target, new_transitions->GetTarget(new_target_index)); |
| 512 | } |
| 513 | } |
| 514 | } |
| 515 | #endif |
| 516 | |
| 517 | |
| 518 | // Private non-static helper functions (operating on full transition arrays). |
| 519 | |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 520 | int TransitionArray::SearchDetails(int transition, PropertyKind kind, |
| 521 | PropertyAttributes attributes, |
| 522 | int* out_insertion_index) { |
| 523 | int nof_transitions = number_of_transitions(); |
| 524 | DCHECK(transition < nof_transitions); |
| 525 | Name* key = GetKey(transition); |
| 526 | for (; transition < nof_transitions && GetKey(transition) == key; |
| 527 | transition++) { |
| 528 | Map* target = GetTarget(transition); |
| 529 | PropertyDetails target_details = GetTargetDetails(key, target); |
| 530 | |
| 531 | int cmp = CompareDetails(kind, attributes, target_details.kind(), |
| 532 | target_details.attributes()); |
| 533 | if (cmp == 0) { |
| 534 | return transition; |
| 535 | } else if (cmp < 0) { |
| 536 | break; |
| 537 | } |
| 538 | } |
| 539 | if (out_insertion_index != NULL) *out_insertion_index = transition; |
| 540 | return kNotFound; |
| 541 | } |
| 542 | |
| 543 | |
| 544 | int TransitionArray::Search(PropertyKind kind, Name* name, |
| 545 | PropertyAttributes attributes, |
| 546 | int* out_insertion_index) { |
| 547 | int transition = SearchName(name, out_insertion_index); |
| 548 | if (transition == kNotFound) { |
| 549 | return kNotFound; |
| 550 | } |
| 551 | return SearchDetails(transition, kind, attributes, out_insertion_index); |
| 552 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 553 | } // namespace internal |
| 554 | } // namespace v8 |