| File: | out/../deps/v8/src/handles/global-handles.cc |
| Warning: | line 1085, column 7 Value stored to 'to_node' is never read |
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| 1 | // Copyright 2009 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 | #include "src/handles/global-handles.h" |
| 6 | |
| 7 | #include <algorithm> |
| 8 | #include <atomic> |
| 9 | #include <climits> |
| 10 | #include <cstdint> |
| 11 | #include <map> |
| 12 | |
| 13 | #include "include/v8-traced-handle.h" |
| 14 | #include "src/api/api-inl.h" |
| 15 | #include "src/base/bits.h" |
| 16 | #include "src/base/compiler-specific.h" |
| 17 | #include "src/base/sanitizer/asan.h" |
| 18 | #include "src/common/allow-deprecated.h" |
| 19 | #include "src/common/globals.h" |
| 20 | #include "src/execution/vm-state-inl.h" |
| 21 | #include "src/heap/base/stack.h" |
| 22 | #include "src/heap/embedder-tracing.h" |
| 23 | #include "src/heap/heap-inl.h" |
| 24 | #include "src/heap/heap-write-barrier-inl.h" |
| 25 | #include "src/heap/heap-write-barrier.h" |
| 26 | #include "src/init/v8.h" |
| 27 | #include "src/logging/counters.h" |
| 28 | #include "src/objects/objects-inl.h" |
| 29 | #include "src/objects/slots.h" |
| 30 | #include "src/objects/visitors.h" |
| 31 | #include "src/tasks/cancelable-task.h" |
| 32 | #include "src/tasks/task-utils.h" |
| 33 | #include "src/utils/utils.h" |
| 34 | |
| 35 | namespace v8 { |
| 36 | namespace internal { |
| 37 | |
| 38 | namespace { |
| 39 | |
| 40 | constexpr size_t kBlockSize = 256; |
| 41 | |
| 42 | } // namespace |
| 43 | |
| 44 | template <class _NodeType> |
| 45 | class GlobalHandles::NodeBlock final { |
| 46 | public: |
| 47 | using BlockType = NodeBlock<_NodeType>; |
| 48 | using NodeType = _NodeType; |
| 49 | |
| 50 | V8_INLINEinline __attribute__((always_inline)) static const NodeBlock* From(const NodeType* node); |
| 51 | V8_INLINEinline __attribute__((always_inline)) static NodeBlock* From(NodeType* node); |
| 52 | |
| 53 | NodeBlock(GlobalHandles* global_handles, |
| 54 | GlobalHandles::NodeSpace<NodeType>* space, |
| 55 | NodeBlock* next) V8_NOEXCEPTnoexcept : next_(next), |
| 56 | global_handles_(global_handles), |
| 57 | space_(space) {} |
| 58 | |
| 59 | NodeBlock(const NodeBlock&) = delete; |
| 60 | NodeBlock& operator=(const NodeBlock&) = delete; |
| 61 | |
| 62 | NodeType* at(size_t index) { return &nodes_[index]; } |
| 63 | const NodeType* at(size_t index) const { return &nodes_[index]; } |
| 64 | GlobalHandles::NodeSpace<NodeType>* space() const { return space_; } |
| 65 | GlobalHandles* global_handles() const { return global_handles_; } |
| 66 | |
| 67 | V8_INLINEinline __attribute__((always_inline)) bool IncreaseUsage(); |
| 68 | V8_INLINEinline __attribute__((always_inline)) bool DecreaseUsage(); |
| 69 | |
| 70 | V8_INLINEinline __attribute__((always_inline)) void ListAdd(NodeBlock** top); |
| 71 | V8_INLINEinline __attribute__((always_inline)) void ListRemove(NodeBlock** top); |
| 72 | |
| 73 | NodeBlock* next() const { return next_; } |
| 74 | NodeBlock* next_used() const { return next_used_; } |
| 75 | |
| 76 | void set_markbit(size_t index) { |
| 77 | const auto [cell, bit] = CellAndBit(index); |
| 78 | reinterpret_cast<std::atomic<CellType>&>(mark_bits_[cell]) |
| 79 | .fetch_or(CellType{1} << bit, std::memory_order_relaxed); |
| 80 | } |
| 81 | |
| 82 | void clear_markbit(size_t index) { |
| 83 | const auto [cell, bit] = CellAndBit(index); |
| 84 | mark_bits_[cell] &= ~(CellType{1} << bit); |
| 85 | } |
| 86 | |
| 87 | bool markbit(size_t index) const { |
| 88 | const auto [cell, bit] = CellAndBit(index); |
| 89 | return mark_bits_[cell] & CellType{1} << bit; |
| 90 | } |
| 91 | |
| 92 | private: |
| 93 | using CellType = uint32_t; |
| 94 | |
| 95 | std::tuple<CellType, CellType> CellAndBit(size_t index) const { |
| 96 | static constexpr CellType kMarkBitCellSizeLog2 = 5; |
| 97 | static_assert(base::bits::IsPowerOfTwo(kBlockSize), |
| 98 | "Block size must be power of two."); |
| 99 | static_assert( |
| 100 | sizeof(CellType) * CHAR_BIT8 == (CellType{1} << kMarkBitCellSizeLog2), |
| 101 | "Markbit CellType not matching defined log2 size."); |
| 102 | static constexpr CellType kCellMask = |
| 103 | (CellType{1} << kMarkBitCellSizeLog2) - 1; |
| 104 | return {static_cast<CellType>(index >> kMarkBitCellSizeLog2), |
| 105 | index & kCellMask}; |
| 106 | } |
| 107 | |
| 108 | NodeType nodes_[kBlockSize]; |
| 109 | NodeBlock* const next_; |
| 110 | GlobalHandles* const global_handles_; |
| 111 | GlobalHandles::NodeSpace<NodeType>* const space_; |
| 112 | NodeBlock* next_used_ = nullptr; |
| 113 | NodeBlock* prev_used_ = nullptr; |
| 114 | uint32_t used_nodes_ = 0; |
| 115 | CellType mark_bits_[kBlockSize / (sizeof(CellType) * CHAR_BIT8)] = {0}; |
| 116 | }; |
| 117 | |
| 118 | template <class NodeType> |
| 119 | const GlobalHandles::NodeBlock<NodeType>* |
| 120 | GlobalHandles::NodeBlock<NodeType>::From(const NodeType* node) { |
| 121 | const NodeType* firstNode = node - node->index(); |
| 122 | const BlockType* block = reinterpret_cast<const BlockType*>(firstNode); |
| 123 | DCHECK_EQ(node, block->at(node->index()))((void) 0); |
| 124 | return block; |
| 125 | } |
| 126 | |
| 127 | template <class NodeType> |
| 128 | GlobalHandles::NodeBlock<NodeType>* GlobalHandles::NodeBlock<NodeType>::From( |
| 129 | NodeType* node) { |
| 130 | NodeType* firstNode = node - node->index(); |
| 131 | BlockType* block = reinterpret_cast<BlockType*>(firstNode); |
| 132 | DCHECK_EQ(node, block->at(node->index()))((void) 0); |
| 133 | return block; |
| 134 | } |
| 135 | |
| 136 | template <class NodeType> |
| 137 | bool GlobalHandles::NodeBlock<NodeType>::IncreaseUsage() { |
| 138 | DCHECK_LT(used_nodes_, kBlockSize)((void) 0); |
| 139 | return used_nodes_++ == 0; |
| 140 | } |
| 141 | |
| 142 | template <class NodeType> |
| 143 | void GlobalHandles::NodeBlock<NodeType>::ListAdd(BlockType** top) { |
| 144 | BlockType* old_top = *top; |
| 145 | *top = this; |
| 146 | next_used_ = old_top; |
| 147 | prev_used_ = nullptr; |
| 148 | if (old_top != nullptr) { |
| 149 | old_top->prev_used_ = this; |
| 150 | } |
| 151 | } |
| 152 | |
| 153 | template <class NodeType> |
| 154 | bool GlobalHandles::NodeBlock<NodeType>::DecreaseUsage() { |
| 155 | DCHECK_GT(used_nodes_, 0)((void) 0); |
| 156 | return --used_nodes_ == 0; |
| 157 | } |
| 158 | |
| 159 | template <class NodeType> |
| 160 | void GlobalHandles::NodeBlock<NodeType>::ListRemove(BlockType** top) { |
| 161 | if (next_used_ != nullptr) next_used_->prev_used_ = prev_used_; |
| 162 | if (prev_used_ != nullptr) prev_used_->next_used_ = next_used_; |
| 163 | if (this == *top) { |
| 164 | *top = next_used_; |
| 165 | } |
| 166 | } |
| 167 | |
| 168 | template <class BlockType> |
| 169 | class GlobalHandles::NodeIterator final { |
| 170 | public: |
| 171 | using NodeType = typename BlockType::NodeType; |
| 172 | |
| 173 | // Iterator traits. |
| 174 | using iterator_category = std::forward_iterator_tag; |
| 175 | using difference_type = std::ptrdiff_t; |
| 176 | using value_type = NodeType*; |
| 177 | using reference = value_type; |
| 178 | using pointer = value_type*; |
| 179 | |
| 180 | explicit NodeIterator(BlockType* block) V8_NOEXCEPTnoexcept : block_(block) {} |
| 181 | NodeIterator(NodeIterator&& other) V8_NOEXCEPTnoexcept : block_(other.block_), |
| 182 | index_(other.index_) {} |
| 183 | |
| 184 | NodeIterator(const NodeIterator&) = delete; |
| 185 | NodeIterator& operator=(const NodeIterator&) = delete; |
| 186 | |
| 187 | bool operator==(const NodeIterator& other) const { |
| 188 | return block_ == other.block_; |
| 189 | } |
| 190 | bool operator!=(const NodeIterator& other) const { |
| 191 | return block_ != other.block_; |
| 192 | } |
| 193 | |
| 194 | NodeIterator& operator++() { |
| 195 | if (++index_ < kBlockSize) return *this; |
| 196 | index_ = 0; |
| 197 | block_ = block_->next_used(); |
| 198 | return *this; |
| 199 | } |
| 200 | |
| 201 | NodeType* operator*() { return block_->at(index_); } |
| 202 | NodeType* operator->() { return block_->at(index_); } |
| 203 | |
| 204 | private: |
| 205 | BlockType* block_ = nullptr; |
| 206 | size_t index_ = 0; |
| 207 | }; |
| 208 | |
| 209 | template <class NodeType> |
| 210 | class GlobalHandles::NodeSpace final { |
| 211 | public: |
| 212 | using BlockType = NodeBlock<NodeType>; |
| 213 | using iterator = NodeIterator<BlockType>; |
| 214 | |
| 215 | static NodeSpace* From(NodeType* node); |
| 216 | static void Release(NodeType* node); |
| 217 | |
| 218 | explicit NodeSpace(GlobalHandles* global_handles) V8_NOEXCEPTnoexcept |
| 219 | : global_handles_(global_handles) {} |
| 220 | ~NodeSpace(); |
| 221 | |
| 222 | V8_INLINEinline __attribute__((always_inline)) NodeType* Acquire(Object object); |
| 223 | |
| 224 | iterator begin() { return iterator(first_used_block_); } |
| 225 | iterator end() { return iterator(nullptr); } |
| 226 | |
| 227 | size_t TotalSize() const { return blocks_ * sizeof(NodeType) * kBlockSize; } |
| 228 | size_t handles_count() const { return handles_count_; } |
| 229 | |
| 230 | private: |
| 231 | void PutNodesOnFreeList(BlockType* block); |
| 232 | V8_INLINEinline __attribute__((always_inline)) void Free(NodeType* node); |
| 233 | |
| 234 | GlobalHandles* const global_handles_; |
| 235 | BlockType* first_block_ = nullptr; |
| 236 | BlockType* first_used_block_ = nullptr; |
| 237 | NodeType* first_free_ = nullptr; |
| 238 | size_t blocks_ = 0; |
| 239 | size_t handles_count_ = 0; |
| 240 | }; |
| 241 | |
| 242 | template <class NodeType> |
| 243 | GlobalHandles::NodeSpace<NodeType>::~NodeSpace() { |
| 244 | auto* block = first_block_; |
| 245 | while (block != nullptr) { |
| 246 | auto* tmp = block->next(); |
| 247 | delete block; |
| 248 | block = tmp; |
| 249 | } |
| 250 | } |
| 251 | |
| 252 | template <class NodeType> |
| 253 | NodeType* GlobalHandles::NodeSpace<NodeType>::Acquire(Object object) { |
| 254 | if (first_free_ == nullptr) { |
| 255 | first_block_ = new BlockType(global_handles_, this, first_block_); |
| 256 | blocks_++; |
| 257 | PutNodesOnFreeList(first_block_); |
| 258 | } |
| 259 | DCHECK_NOT_NULL(first_free_)((void) 0); |
| 260 | NodeType* node = first_free_; |
| 261 | first_free_ = first_free_->next_free(); |
| 262 | node->Acquire(object); |
| 263 | BlockType* block = BlockType::From(node); |
| 264 | if (block->IncreaseUsage()) { |
| 265 | block->ListAdd(&first_used_block_); |
| 266 | } |
| 267 | global_handles_->isolate()->counters()->global_handles()->Increment(); |
| 268 | handles_count_++; |
| 269 | DCHECK(node->IsInUse())((void) 0); |
| 270 | return node; |
| 271 | } |
| 272 | |
| 273 | template <class NodeType> |
| 274 | void GlobalHandles::NodeSpace<NodeType>::PutNodesOnFreeList(BlockType* block) { |
| 275 | for (int32_t i = kBlockSize - 1; i >= 0; --i) { |
| 276 | NodeType* node = block->at(i); |
| 277 | const uint8_t index = static_cast<uint8_t>(i); |
| 278 | DCHECK_EQ(i, index)((void) 0); |
| 279 | node->set_index(index); |
| 280 | node->Free(first_free_); |
| 281 | first_free_ = node; |
| 282 | } |
| 283 | } |
| 284 | |
| 285 | template <class NodeType> |
| 286 | void GlobalHandles::NodeSpace<NodeType>::Release(NodeType* node) { |
| 287 | BlockType* block = BlockType::From(node); |
| 288 | block->space()->Free(node); |
| 289 | } |
| 290 | |
| 291 | template <class NodeType> |
| 292 | void GlobalHandles::NodeSpace<NodeType>::Free(NodeType* node) { |
| 293 | node->Release(first_free_); |
| 294 | first_free_ = node; |
| 295 | BlockType* block = BlockType::From(node); |
| 296 | if (block->DecreaseUsage()) { |
| 297 | block->ListRemove(&first_used_block_); |
| 298 | } |
| 299 | global_handles_->isolate()->counters()->global_handles()->Decrement(); |
| 300 | handles_count_--; |
| 301 | } |
| 302 | |
| 303 | template <class Child> |
| 304 | class NodeBase { |
| 305 | public: |
| 306 | static const Child* FromLocation(const Address* location) { |
| 307 | return reinterpret_cast<const Child*>(location); |
| 308 | } |
| 309 | |
| 310 | static Child* FromLocation(Address* location) { |
| 311 | return reinterpret_cast<Child*>(location); |
| 312 | } |
| 313 | |
| 314 | NodeBase() { |
| 315 | DCHECK_EQ(offsetof(NodeBase, object_), 0)((void) 0); |
| 316 | DCHECK_EQ(offsetof(NodeBase, class_id_), Internals::kNodeClassIdOffset)((void) 0); |
| 317 | DCHECK_EQ(offsetof(NodeBase, flags_), Internals::kNodeFlagsOffset)((void) 0); |
| 318 | } |
| 319 | |
| 320 | #ifdef ENABLE_HANDLE_ZAPPING |
| 321 | ~NodeBase() { |
| 322 | ClearFields(); |
| 323 | data_.next_free = nullptr; |
| 324 | index_ = 0; |
| 325 | } |
| 326 | #endif |
| 327 | |
| 328 | void Free(Child* free_list) { |
| 329 | ClearFields(); |
| 330 | AsChild()->MarkAsFree(); |
| 331 | data_.next_free = free_list; |
| 332 | } |
| 333 | |
| 334 | void Acquire(Object object) { |
| 335 | DCHECK(!AsChild()->IsInUse())((void) 0); |
| 336 | CheckFieldsAreCleared(); |
| 337 | reinterpret_cast<std::atomic<Address>*>(&object_)->store( |
| 338 | object.ptr(), std::memory_order_relaxed); |
| 339 | AsChild()->MarkAsUsed(); |
| 340 | data_.parameter = nullptr; |
| 341 | DCHECK(AsChild()->IsInUse())((void) 0); |
| 342 | } |
| 343 | |
| 344 | void Release(Child* free_list) { |
| 345 | DCHECK(AsChild()->IsInUse())((void) 0); |
| 346 | Free(free_list); |
| 347 | DCHECK(!AsChild()->IsInUse())((void) 0); |
| 348 | } |
| 349 | |
| 350 | Object object() const { return Object(object_); } |
| 351 | FullObjectSlot location() { return FullObjectSlot(&object_); } |
| 352 | Handle<Object> handle() { return Handle<Object>(&object_); } |
| 353 | |
| 354 | uint8_t index() const { return index_; } |
| 355 | void set_index(uint8_t value) { index_ = value; } |
| 356 | |
| 357 | uint16_t wrapper_class_id() const { return class_id_; } |
| 358 | bool has_wrapper_class_id() const { |
| 359 | return class_id_ != v8::HeapProfiler::kPersistentHandleNoClassId; |
| 360 | } |
| 361 | |
| 362 | // Accessors for next free node in the free list. |
| 363 | Child* next_free() { |
| 364 | DCHECK(!AsChild()->IsInUse())((void) 0); |
| 365 | return data_.next_free; |
| 366 | } |
| 367 | |
| 368 | void set_parameter(void* parameter) { |
| 369 | DCHECK(AsChild()->IsInUse())((void) 0); |
| 370 | data_.parameter = parameter; |
| 371 | } |
| 372 | void* parameter() const { |
| 373 | DCHECK(AsChild()->IsInUse())((void) 0); |
| 374 | return data_.parameter; |
| 375 | } |
| 376 | |
| 377 | protected: |
| 378 | Child* AsChild() { return reinterpret_cast<Child*>(this); } |
| 379 | const Child* AsChild() const { return reinterpret_cast<const Child*>(this); } |
| 380 | |
| 381 | void ClearFields() { |
| 382 | // Zap the values for eager trapping. |
| 383 | object_ = kGlobalHandleZapValue; |
| 384 | class_id_ = v8::HeapProfiler::kPersistentHandleNoClassId; |
| 385 | AsChild()->ClearImplFields(); |
| 386 | } |
| 387 | |
| 388 | void CheckFieldsAreCleared() { |
| 389 | DCHECK_EQ(kGlobalHandleZapValue, object_)((void) 0); |
| 390 | DCHECK_EQ(v8::HeapProfiler::kPersistentHandleNoClassId, class_id_)((void) 0); |
| 391 | AsChild()->CheckImplFieldsAreCleared(); |
| 392 | } |
| 393 | |
| 394 | // Storage for object pointer. |
| 395 | // |
| 396 | // Placed first to avoid offset computation. The stored data is equivalent to |
| 397 | // an Object. It is stored as a plain Address for convenience (smallest number |
| 398 | // of casts), and because it is a private implementation detail: the public |
| 399 | // interface provides type safety. |
| 400 | Address object_; |
| 401 | |
| 402 | // Class id set by the embedder. |
| 403 | uint16_t class_id_; |
| 404 | |
| 405 | // Index in the containing handle block. |
| 406 | uint8_t index_; |
| 407 | |
| 408 | uint8_t flags_; |
| 409 | |
| 410 | // The meaning of this field depends on node state: |
| 411 | // - Node in free list: Stores next free node pointer. |
| 412 | // - Otherwise, specific to the node implementation. |
| 413 | union { |
| 414 | Child* next_free; |
| 415 | void* parameter; |
| 416 | } data_; |
| 417 | }; |
| 418 | |
| 419 | namespace { |
| 420 | |
| 421 | void ExtractInternalFields(JSObject jsobject, void** embedder_fields, int len) { |
| 422 | int field_count = jsobject.GetEmbedderFieldCount(); |
| 423 | Isolate* isolate = GetIsolateForSandbox(jsobject); |
| 424 | for (int i = 0; i < len; ++i) { |
| 425 | if (field_count == i) break; |
| 426 | void* pointer; |
| 427 | if (EmbedderDataSlot(jsobject, i).ToAlignedPointer(isolate, &pointer)) { |
| 428 | embedder_fields[i] = pointer; |
| 429 | } |
| 430 | } |
| 431 | } |
| 432 | |
| 433 | } // namespace |
| 434 | |
| 435 | class GlobalHandles::Node final : public NodeBase<GlobalHandles::Node> { |
| 436 | public: |
| 437 | // State transition diagram: |
| 438 | // FREE -> NORMAL <-> WEAK -> PENDING -> NEAR_DEATH -> { NORMAL, WEAK, FREE } |
| 439 | enum State { |
| 440 | FREE = 0, |
| 441 | NORMAL, // Normal global handle. |
| 442 | WEAK, // Flagged as weak but not yet finalized. |
| 443 | PENDING, // Has been recognized as only reachable by weak handles. |
| 444 | NEAR_DEATH, // Callback has informed the handle is near death. |
| 445 | NUMBER_OF_NODE_STATES |
| 446 | }; |
| 447 | |
| 448 | Node() { |
| 449 | STATIC_ASSERT(static_cast<int>(NodeState::kMask) ==static_assert(static_cast<int>(NodeState::kMask) == Internals ::kNodeStateMask, "static_cast<int>(NodeState::kMask) == Internals::kNodeStateMask" ) |
| 450 | Internals::kNodeStateMask)static_assert(static_cast<int>(NodeState::kMask) == Internals ::kNodeStateMask, "static_cast<int>(NodeState::kMask) == Internals::kNodeStateMask" ); |
| 451 | STATIC_ASSERT(WEAK == Internals::kNodeStateIsWeakValue)static_assert(WEAK == Internals::kNodeStateIsWeakValue, "WEAK == Internals::kNodeStateIsWeakValue" ); |
| 452 | STATIC_ASSERT(PENDING == Internals::kNodeStateIsPendingValue)static_assert(PENDING == Internals::kNodeStateIsPendingValue, "PENDING == Internals::kNodeStateIsPendingValue"); |
| 453 | set_in_young_list(false); |
| 454 | } |
| 455 | |
| 456 | Node(const Node&) = delete; |
| 457 | Node& operator=(const Node&) = delete; |
| 458 | |
| 459 | const char* label() const { |
| 460 | return state() == NORMAL ? reinterpret_cast<char*>(data_.parameter) |
| 461 | : nullptr; |
| 462 | } |
| 463 | |
| 464 | // State and flag accessors. |
| 465 | |
| 466 | State state() const { return NodeState::decode(flags_); } |
| 467 | void set_state(State state) { flags_ = NodeState::update(flags_, state); } |
| 468 | |
| 469 | bool is_in_young_list() const { return IsInYoungList::decode(flags_); } |
| 470 | void set_in_young_list(bool v) { flags_ = IsInYoungList::update(flags_, v); } |
| 471 | |
| 472 | WeaknessType weakness_type() const { |
| 473 | return NodeWeaknessType::decode(flags_); |
| 474 | } |
| 475 | void set_weakness_type(WeaknessType weakness_type) { |
| 476 | flags_ = NodeWeaknessType::update(flags_, weakness_type); |
| 477 | } |
| 478 | |
| 479 | bool IsWeak() const { return state() == WEAK; } |
| 480 | |
| 481 | bool IsInUse() const { return state() != FREE; } |
| 482 | |
| 483 | bool IsPhantomCallback() const { |
| 484 | return weakness_type() == PHANTOM_WEAK || |
| 485 | weakness_type() == PHANTOM_WEAK_2_EMBEDDER_FIELDS; |
| 486 | } |
| 487 | |
| 488 | bool IsPhantomResetHandle() const { |
| 489 | return weakness_type() == PHANTOM_WEAK_RESET_HANDLE; |
| 490 | } |
| 491 | |
| 492 | bool IsFinalizerHandle() const { return weakness_type() == FINALIZER_WEAK; } |
| 493 | |
| 494 | bool IsPendingPhantomCallback() const { |
| 495 | return state() == PENDING && IsPhantomCallback(); |
| 496 | } |
| 497 | |
| 498 | bool IsPendingPhantomResetHandle() const { |
| 499 | return state() == PENDING && IsPhantomResetHandle(); |
| 500 | } |
| 501 | |
| 502 | bool IsPendingFinalizer() const { |
| 503 | return state() == PENDING && weakness_type() == FINALIZER_WEAK; |
| 504 | } |
| 505 | |
| 506 | bool IsPending() const { return state() == PENDING; } |
| 507 | |
| 508 | bool IsRetainer() const { |
| 509 | return state() != FREE && |
| 510 | !(state() == NEAR_DEATH && weakness_type() != FINALIZER_WEAK); |
| 511 | } |
| 512 | |
| 513 | bool IsStrongRetainer() const { return state() == NORMAL; } |
| 514 | |
| 515 | bool IsWeakRetainer() const { |
| 516 | return state() == WEAK || state() == PENDING || |
| 517 | (state() == NEAR_DEATH && weakness_type() == FINALIZER_WEAK); |
| 518 | } |
| 519 | |
| 520 | void MarkPending() { |
| 521 | DCHECK(state() == WEAK)((void) 0); |
| 522 | set_state(PENDING); |
| 523 | } |
| 524 | |
| 525 | bool has_callback() const { return weak_callback_ != nullptr; } |
| 526 | |
| 527 | // Accessors for next free node in the free list. |
| 528 | Node* next_free() { |
| 529 | DCHECK_EQ(FREE, state())((void) 0); |
| 530 | return data_.next_free; |
| 531 | } |
| 532 | |
| 533 | void MakeWeak(void* parameter, |
| 534 | WeakCallbackInfo<void>::Callback phantom_callback, |
| 535 | v8::WeakCallbackType type) { |
| 536 | DCHECK_NOT_NULL(phantom_callback)((void) 0); |
| 537 | DCHECK(IsInUse())((void) 0); |
| 538 | CHECK_NE(object_, kGlobalHandleZapValue)do { bool _cmp = ::v8::base::CmpNEImpl< typename ::v8::base ::pass_value_or_ref<decltype(object_)>::type, typename :: v8::base::pass_value_or_ref<decltype(kGlobalHandleZapValue )>::type>((object_), (kGlobalHandleZapValue)); do { if ( (__builtin_expect(!!(!(_cmp)), 0))) { V8_Fatal("Check failed: %s." , "object_" " " "!=" " " "kGlobalHandleZapValue"); } } while ( false); } while (false); |
| 539 | set_state(WEAK); |
| 540 | switch (type) { |
| 541 | case v8::WeakCallbackType::kParameter: |
| 542 | set_weakness_type(PHANTOM_WEAK); |
| 543 | break; |
| 544 | case v8::WeakCallbackType::kInternalFields: |
| 545 | set_weakness_type(PHANTOM_WEAK_2_EMBEDDER_FIELDS); |
| 546 | break; |
| 547 | START_ALLOW_USE_DEPRECATED() |
| 548 | case v8::WeakCallbackType::kFinalizer: |
| 549 | set_weakness_type(FINALIZER_WEAK); |
| 550 | break; |
| 551 | END_ALLOW_USE_DEPRECATED() |
| 552 | } |
| 553 | set_parameter(parameter); |
| 554 | weak_callback_ = phantom_callback; |
| 555 | } |
| 556 | |
| 557 | void MakeWeak(Address** location_addr) { |
| 558 | DCHECK(IsInUse())((void) 0); |
| 559 | CHECK_NE(object_, kGlobalHandleZapValue)do { bool _cmp = ::v8::base::CmpNEImpl< typename ::v8::base ::pass_value_or_ref<decltype(object_)>::type, typename :: v8::base::pass_value_or_ref<decltype(kGlobalHandleZapValue )>::type>((object_), (kGlobalHandleZapValue)); do { if ( (__builtin_expect(!!(!(_cmp)), 0))) { V8_Fatal("Check failed: %s." , "object_" " " "!=" " " "kGlobalHandleZapValue"); } } while ( false); } while (false); |
| 560 | set_state(WEAK); |
| 561 | set_weakness_type(PHANTOM_WEAK_RESET_HANDLE); |
| 562 | set_parameter(location_addr); |
| 563 | weak_callback_ = nullptr; |
| 564 | } |
| 565 | |
| 566 | void* ClearWeakness() { |
| 567 | DCHECK(IsInUse())((void) 0); |
| 568 | void* p = parameter(); |
| 569 | set_state(NORMAL); |
| 570 | set_parameter(nullptr); |
| 571 | return p; |
| 572 | } |
| 573 | |
| 574 | void AnnotateStrongRetainer(const char* label) { |
| 575 | DCHECK_EQ(state(), NORMAL)((void) 0); |
| 576 | data_.parameter = const_cast<char*>(label); |
| 577 | } |
| 578 | |
| 579 | void CollectPhantomCallbackData( |
| 580 | std::vector<std::pair<Node*, PendingPhantomCallback>>* |
| 581 | pending_phantom_callbacks) { |
| 582 | DCHECK(weakness_type() == PHANTOM_WEAK ||((void) 0) |
| 583 | weakness_type() == PHANTOM_WEAK_2_EMBEDDER_FIELDS)((void) 0); |
| 584 | DCHECK(state() == PENDING)((void) 0); |
| 585 | DCHECK_NOT_NULL(weak_callback_)((void) 0); |
| 586 | |
| 587 | void* embedder_fields[v8::kEmbedderFieldsInWeakCallback] = {nullptr, |
| 588 | nullptr}; |
| 589 | if (weakness_type() != PHANTOM_WEAK && object().IsJSObject()) { |
| 590 | ExtractInternalFields(JSObject::cast(object()), embedder_fields, |
| 591 | v8::kEmbedderFieldsInWeakCallback); |
| 592 | } |
| 593 | |
| 594 | // Zap with something dangerous. |
| 595 | location().store(Object(0xCA11)); |
| 596 | |
| 597 | pending_phantom_callbacks->push_back(std::make_pair( |
| 598 | this, |
| 599 | PendingPhantomCallback(weak_callback_, parameter(), embedder_fields))); |
| 600 | DCHECK(IsInUse())((void) 0); |
| 601 | set_state(NEAR_DEATH); |
| 602 | } |
| 603 | |
| 604 | void ResetPhantomHandle() { |
| 605 | DCHECK_EQ(PHANTOM_WEAK_RESET_HANDLE, weakness_type())((void) 0); |
| 606 | DCHECK_EQ(PENDING, state())((void) 0); |
| 607 | DCHECK_NULL(weak_callback_)((void) 0); |
| 608 | Address** handle = reinterpret_cast<Address**>(parameter()); |
| 609 | *handle = nullptr; |
| 610 | NodeSpace<Node>::Release(this); |
| 611 | } |
| 612 | |
| 613 | void PostGarbageCollectionProcessing(Isolate* isolate) { |
| 614 | // This method invokes a finalizer. Updating the method name would require |
| 615 | // adjusting CFI blocklist as weak_callback_ is invoked on the wrong type. |
| 616 | CHECK(IsPendingFinalizer())do { if ((__builtin_expect(!!(!(IsPendingFinalizer())), 0))) { V8_Fatal("Check failed: %s.", "IsPendingFinalizer()"); } } while (false); |
| 617 | set_state(NEAR_DEATH); |
| 618 | // Check that we are not passing a finalized external string to |
| 619 | // the callback. |
| 620 | DCHECK(!object().IsExternalOneByteString() ||((void) 0) |
| 621 | ExternalOneByteString::cast(object()).resource() != nullptr)((void) 0); |
| 622 | DCHECK(!object().IsExternalTwoByteString() ||((void) 0) |
| 623 | ExternalTwoByteString::cast(object()).resource() != nullptr)((void) 0); |
| 624 | // Leaving V8. |
| 625 | VMState<EXTERNAL> vmstate(isolate); |
| 626 | HandleScope handle_scope(isolate); |
| 627 | void* embedder_fields[v8::kEmbedderFieldsInWeakCallback] = {nullptr, |
| 628 | nullptr}; |
| 629 | v8::WeakCallbackInfo<void> data(reinterpret_cast<v8::Isolate*>(isolate), |
| 630 | parameter(), embedder_fields, nullptr); |
| 631 | weak_callback_(data); |
| 632 | // For finalizers the handle must have either been reset or made strong. |
| 633 | // Both cases reset the state. |
| 634 | CHECK_NE(NEAR_DEATH, state())do { bool _cmp = ::v8::base::CmpNEImpl< typename ::v8::base ::pass_value_or_ref<decltype(NEAR_DEATH)>::type, typename ::v8::base::pass_value_or_ref<decltype(state())>::type >((NEAR_DEATH), (state())); do { if ((__builtin_expect(!!( !(_cmp)), 0))) { V8_Fatal("Check failed: %s.", "NEAR_DEATH" " " "!=" " " "state()"); } } while (false); } while (false); |
| 635 | } |
| 636 | |
| 637 | void MarkAsFree() { set_state(FREE); } |
| 638 | void MarkAsUsed() { set_state(NORMAL); } |
| 639 | |
| 640 | GlobalHandles* global_handles() { |
| 641 | return NodeBlock<Node>::From(this)->global_handles(); |
| 642 | } |
| 643 | |
| 644 | private: |
| 645 | // Fields that are not used for managing node memory. |
| 646 | void ClearImplFields() { weak_callback_ = nullptr; } |
| 647 | |
| 648 | void CheckImplFieldsAreCleared() { DCHECK_EQ(nullptr, weak_callback_)((void) 0); } |
| 649 | |
| 650 | // This stores three flags (independent, partially_dependent and |
| 651 | // in_young_list) and a State. |
| 652 | using NodeState = base::BitField8<State, 0, 3>; |
| 653 | using IsInYoungList = NodeState::Next<bool, 1>; |
| 654 | using NodeWeaknessType = IsInYoungList::Next<WeaknessType, 2>; |
| 655 | |
| 656 | // Handle specific callback - might be a weak reference in disguise. |
| 657 | WeakCallbackInfo<void>::Callback weak_callback_; |
| 658 | |
| 659 | friend class NodeBase<Node>; |
| 660 | }; |
| 661 | |
| 662 | class GlobalHandles::TracedNode final |
| 663 | : public NodeBase<GlobalHandles::TracedNode> { |
| 664 | public: |
| 665 | TracedNode() { set_in_young_list(false); } |
| 666 | |
| 667 | // Copy and move ctors are used when constructing a TracedNode when recording |
| 668 | // a node for on-stack data structures. (Older compilers may refer to copy |
| 669 | // instead of move ctor.) |
| 670 | TracedNode(TracedNode&& other) V8_NOEXCEPTnoexcept = default; |
| 671 | TracedNode(const TracedNode& other) V8_NOEXCEPTnoexcept = default; |
| 672 | |
| 673 | enum State { FREE = 0, NORMAL, NEAR_DEATH }; |
| 674 | |
| 675 | State state() const { return NodeState::decode(flags_); } |
| 676 | void set_state(State state) { flags_ = NodeState::update(flags_, state); } |
| 677 | |
| 678 | void MarkAsFree() { set_state(FREE); } |
| 679 | void MarkAsUsed() { set_state(NORMAL); } |
| 680 | bool IsInUse() const { return state() != FREE; } |
| 681 | bool IsRetainer() const { return state() == NORMAL; } |
| 682 | |
| 683 | bool is_in_young_list() const { return IsInYoungList::decode(flags_); } |
| 684 | void set_in_young_list(bool v) { flags_ = IsInYoungList::update(flags_, v); } |
| 685 | |
| 686 | bool is_root() const { return IsRoot::decode(flags_); } |
| 687 | void set_root(bool v) { flags_ = IsRoot::update(flags_, v); } |
| 688 | |
| 689 | void set_markbit() { |
| 690 | NodeBlock<TracedNode>::From(this)->set_markbit(index()); |
| 691 | } |
| 692 | |
| 693 | bool markbit() const { |
| 694 | return NodeBlock<TracedNode>::From(this)->markbit(index()); |
| 695 | } |
| 696 | void clear_markbit() { |
| 697 | NodeBlock<TracedNode>::From(this)->clear_markbit(index()); |
| 698 | } |
| 699 | |
| 700 | bool is_on_stack() const { return IsOnStack::decode(flags_); } |
| 701 | void set_is_on_stack(bool v) { flags_ = IsOnStack::update(flags_, v); } |
| 702 | |
| 703 | void clear_object() { |
| 704 | reinterpret_cast<std::atomic<Address>*>(&object_)->store( |
| 705 | kNullAddress, std::memory_order_relaxed); |
| 706 | } |
| 707 | |
| 708 | void CopyObjectReference(const TracedNode& other) { |
| 709 | reinterpret_cast<std::atomic<Address>*>(&object_)->store( |
| 710 | other.object_, std::memory_order_relaxed); |
| 711 | } |
| 712 | |
| 713 | void ResetPhantomHandle() { |
| 714 | DCHECK(IsInUse())((void) 0); |
| 715 | NodeSpace<TracedNode>::Release(this); |
| 716 | DCHECK(!IsInUse())((void) 0); |
| 717 | } |
| 718 | |
| 719 | static void Verify(GlobalHandles* global_handles, const Address* const* slot); |
| 720 | |
| 721 | protected: |
| 722 | // Various state is managed in a bit field. Mark bits are used concurrently |
| 723 | // and held externally in a NodeBlock. |
| 724 | using NodeState = base::BitField8<State, 0, 2>; |
| 725 | using IsInYoungList = NodeState::Next<bool, 1>; |
| 726 | using IsRoot = IsInYoungList::Next<bool, 1>; |
| 727 | using IsOnStack = IsRoot::Next<bool, 1>; |
| 728 | void ClearImplFields() { |
| 729 | set_root(true); |
| 730 | set_is_on_stack(false); |
| 731 | } |
| 732 | |
| 733 | void CheckImplFieldsAreCleared() const { DCHECK(is_root())((void) 0); } |
| 734 | |
| 735 | friend class NodeBase<GlobalHandles::TracedNode>; |
| 736 | }; |
| 737 | |
| 738 | // Space to keep track of on-stack handles (e.g. TracedReference). Such |
| 739 | // references are treated as root for any V8 garbage collection. The data |
| 740 | // structure is self healing and pessimistally filters outdated entries on |
| 741 | // insertion and iteration. |
| 742 | // |
| 743 | // Design doc: http://bit.ly/on-stack-traced-reference |
| 744 | class GlobalHandles::OnStackTracedNodeSpace final { |
| 745 | public: |
| 746 | static GlobalHandles* GetGlobalHandles(const TracedNode* on_stack_node) { |
| 747 | DCHECK(on_stack_node->is_on_stack())((void) 0); |
| 748 | return reinterpret_cast<const NodeEntry*>(on_stack_node)->global_handles; |
| 749 | } |
| 750 | |
| 751 | explicit OnStackTracedNodeSpace(GlobalHandles* global_handles) |
| 752 | : global_handles_(global_handles) {} |
| 753 | |
| 754 | void SetStackStart(void* stack_start) { |
| 755 | CHECK(on_stack_nodes_.empty())do { if ((__builtin_expect(!!(!(on_stack_nodes_.empty())), 0) )) { V8_Fatal("Check failed: %s.", "on_stack_nodes_.empty()") ; } } while (false); |
| 756 | stack_.SetStackStart(base::Stack::GetRealStackAddressForSlot(stack_start)); |
| 757 | } |
| 758 | |
| 759 | V8_INLINEinline __attribute__((always_inline)) bool IsOnStack(uintptr_t slot) const; |
| 760 | |
| 761 | void Iterate(RootVisitor* v); |
| 762 | TracedNode* Acquire(Object value, uintptr_t address); |
| 763 | void CleanupBelowCurrentStackPosition(); |
| 764 | void NotifyEmptyEmbedderStack(); |
| 765 | |
| 766 | size_t NumberOfHandlesForTesting() const { return on_stack_nodes_.size(); } |
| 767 | |
| 768 | private: |
| 769 | struct NodeEntry { |
| 770 | TracedNode node; |
| 771 | // Used to find back to GlobalHandles from a Node on copy. Needs to follow |
| 772 | // node. |
| 773 | GlobalHandles* global_handles; |
| 774 | }; |
| 775 | |
| 776 | // Keeps track of registered handles. The data structure is cleaned on |
| 777 | // iteration and when adding new references using the current stack address. |
| 778 | // Cleaning is based on current stack address and the key of the map which is |
| 779 | // slightly different for ASAN configs -- see below. |
| 780 | #ifdef V8_USE_ADDRESS_SANITIZER |
| 781 | // Mapping from stack slots or real stack frames to the corresponding nodes. |
| 782 | // In case a reference is part of a fake frame, we map it to the real stack |
| 783 | // frame base instead of the actual stack slot. The list keeps all nodes for |
| 784 | // a particular real frame. |
| 785 | std::map<uintptr_t, std::list<NodeEntry>> on_stack_nodes_; |
| 786 | #else // !V8_USE_ADDRESS_SANITIZER |
| 787 | // Mapping from stack slots to the corresponding nodes. We don't expect |
| 788 | // aliasing with overlapping lifetimes of nodes. |
| 789 | std::map<uintptr_t, NodeEntry> on_stack_nodes_; |
| 790 | #endif // !V8_USE_ADDRESS_SANITIZER |
| 791 | |
| 792 | ::heap::base::Stack stack_; |
| 793 | GlobalHandles* global_handles_ = nullptr; |
| 794 | size_t acquire_count_ = 0; |
| 795 | }; |
| 796 | |
| 797 | bool GlobalHandles::OnStackTracedNodeSpace::IsOnStack(uintptr_t slot) const { |
| 798 | // By the time this function is called, the stack start may not be set (i.e. |
| 799 | // SetStackStart() was not called). In that case, assume the slot is not on |
| 800 | // stack. |
| 801 | if (!stack_.stack_start()) return false; |
| 802 | return stack_.IsOnStack(reinterpret_cast<void*>(slot)); |
| 803 | } |
| 804 | |
| 805 | void GlobalHandles::OnStackTracedNodeSpace::NotifyEmptyEmbedderStack() { |
| 806 | on_stack_nodes_.clear(); |
| 807 | } |
| 808 | |
| 809 | void GlobalHandles::OnStackTracedNodeSpace::Iterate(RootVisitor* v) { |
| 810 | #ifdef V8_USE_ADDRESS_SANITIZER |
| 811 | for (auto& pair : on_stack_nodes_) { |
| 812 | for (auto& node_entry : pair.second) { |
| 813 | TracedNode& node = node_entry.node; |
| 814 | if (node.IsRetainer()) { |
| 815 | v->VisitRootPointer(Root::kGlobalHandles, "on-stack TracedReference", |
| 816 | node.location()); |
| 817 | } |
| 818 | } |
| 819 | } |
| 820 | #else // !V8_USE_ADDRESS_SANITIZER |
| 821 | // Handles have been cleaned from the GC entry point which is higher up the |
| 822 | // stack. |
| 823 | for (auto& pair : on_stack_nodes_) { |
| 824 | TracedNode& node = pair.second.node; |
| 825 | if (node.IsRetainer()) { |
| 826 | v->VisitRootPointer(Root::kGlobalHandles, "on-stack TracedReference", |
| 827 | node.location()); |
| 828 | } |
| 829 | } |
| 830 | #endif // !V8_USE_ADDRESS_SANITIZER |
| 831 | } |
| 832 | |
| 833 | GlobalHandles::TracedNode* GlobalHandles::OnStackTracedNodeSpace::Acquire( |
| 834 | Object value, uintptr_t slot) { |
| 835 | constexpr size_t kAcquireCleanupThresholdLog2 = 8; |
| 836 | constexpr size_t kAcquireCleanupThresholdMask = |
| 837 | (size_t{1} << kAcquireCleanupThresholdLog2) - 1; |
| 838 | DCHECK(IsOnStack(slot))((void) 0); |
| 839 | if (((acquire_count_++) & kAcquireCleanupThresholdMask) == 0) { |
| 840 | CleanupBelowCurrentStackPosition(); |
| 841 | } |
| 842 | NodeEntry entry; |
| 843 | entry.node.Free(nullptr); |
| 844 | entry.global_handles = global_handles_; |
| 845 | #ifdef V8_USE_ADDRESS_SANITIZER |
| 846 | auto pair = on_stack_nodes_.insert( |
| 847 | {base::Stack::GetRealStackAddressForSlot(slot), {}}); |
| 848 | pair.first->second.push_back(std::move(entry)); |
| 849 | TracedNode* result = &(pair.first->second.back().node); |
| 850 | #else // !V8_USE_ADDRESS_SANITIZER |
| 851 | auto pair = on_stack_nodes_.insert( |
| 852 | {base::Stack::GetRealStackAddressForSlot(slot), std::move(entry)}); |
| 853 | if (!pair.second) { |
| 854 | // Insertion failed because there already was an entry present for that |
| 855 | // stack address. This can happen because cleanup is conservative in which |
| 856 | // stack limits it used. Reusing the entry is fine as there's no aliasing of |
| 857 | // different references with the same stack slot. |
| 858 | pair.first->second.node.Free(nullptr); |
| 859 | } |
| 860 | TracedNode* result = &(pair.first->second.node); |
| 861 | #endif // !V8_USE_ADDRESS_SANITIZER |
| 862 | result->Acquire(value); |
| 863 | result->set_is_on_stack(true); |
| 864 | return result; |
| 865 | } |
| 866 | |
| 867 | void GlobalHandles::OnStackTracedNodeSpace::CleanupBelowCurrentStackPosition() { |
| 868 | if (on_stack_nodes_.empty()) return; |
| 869 | const uintptr_t stack_ptr = reinterpret_cast<uintptr_t>( |
| 870 | ::heap::base::Stack::GetCurrentStackPointerForLocalVariables()); |
| 871 | const auto it = on_stack_nodes_.upper_bound(stack_ptr); |
| 872 | on_stack_nodes_.erase(on_stack_nodes_.begin(), it); |
| 873 | } |
| 874 | |
| 875 | // static |
| 876 | void GlobalHandles::EnableMarkingBarrier(Isolate* isolate) { |
| 877 | auto* global_handles = isolate->global_handles(); |
| 878 | DCHECK(!global_handles->is_marking_)((void) 0); |
| 879 | global_handles->is_marking_ = true; |
| 880 | } |
| 881 | |
| 882 | // static |
| 883 | void GlobalHandles::DisableMarkingBarrier(Isolate* isolate) { |
| 884 | auto* global_handles = isolate->global_handles(); |
| 885 | DCHECK(global_handles->is_marking_)((void) 0); |
| 886 | global_handles->is_marking_ = false; |
| 887 | } |
| 888 | |
| 889 | // static |
| 890 | void GlobalHandles::TracedNode::Verify(GlobalHandles* global_handles, |
| 891 | const Address* const* slot) { |
| 892 | #ifdef DEBUG |
| 893 | const TracedNode* node = FromLocation(*slot); |
| 894 | DCHECK(node->IsInUse())((void) 0); |
| 895 | bool slot_on_stack = global_handles->on_stack_nodes_->IsOnStack( |
| 896 | reinterpret_cast<uintptr_t>(slot)); |
| 897 | DCHECK_EQ(slot_on_stack, node->is_on_stack())((void) 0); |
| 898 | if (!node->is_on_stack()) { |
| 899 | // On-heap nodes have seprate lists for young generation processing. |
| 900 | bool is_young_gen_object = ObjectInYoungGeneration(node->object()); |
| 901 | DCHECK_IMPLIES(is_young_gen_object, node->is_in_young_list())((void) 0); |
| 902 | } |
| 903 | bool in_young_list = |
| 904 | std::find(global_handles->traced_young_nodes_.begin(), |
| 905 | global_handles->traced_young_nodes_.end(), |
| 906 | node) != global_handles->traced_young_nodes_.end(); |
| 907 | DCHECK_EQ(in_young_list, node->is_in_young_list())((void) 0); |
| 908 | #endif // DEBUG |
| 909 | } |
| 910 | |
| 911 | void GlobalHandles::CleanupOnStackReferencesBelowCurrentStackPosition() { |
| 912 | on_stack_nodes_->CleanupBelowCurrentStackPosition(); |
| 913 | } |
| 914 | |
| 915 | size_t GlobalHandles::NumberOfOnStackHandlesForTesting() { |
| 916 | return on_stack_nodes_->NumberOfHandlesForTesting(); |
| 917 | } |
| 918 | |
| 919 | size_t GlobalHandles::TotalSize() const { |
| 920 | return regular_nodes_->TotalSize() + traced_nodes_->TotalSize(); |
| 921 | } |
| 922 | |
| 923 | size_t GlobalHandles::UsedSize() const { |
| 924 | return regular_nodes_->handles_count() * sizeof(Node) + |
| 925 | traced_nodes_->handles_count() * sizeof(TracedNode); |
| 926 | } |
| 927 | |
| 928 | size_t GlobalHandles::handles_count() const { |
| 929 | return regular_nodes_->handles_count() + traced_nodes_->handles_count(); |
| 930 | } |
| 931 | |
| 932 | void GlobalHandles::SetStackStart(void* stack_start) { |
| 933 | on_stack_nodes_->SetStackStart(stack_start); |
| 934 | } |
| 935 | |
| 936 | void GlobalHandles::NotifyEmptyEmbedderStack() { |
| 937 | on_stack_nodes_->NotifyEmptyEmbedderStack(); |
| 938 | } |
| 939 | |
| 940 | GlobalHandles::GlobalHandles(Isolate* isolate) |
| 941 | : isolate_(isolate), |
| 942 | regular_nodes_(new NodeSpace<GlobalHandles::Node>(this)), |
| 943 | traced_nodes_(new NodeSpace<GlobalHandles::TracedNode>(this)), |
| 944 | on_stack_nodes_(new OnStackTracedNodeSpace(this)) {} |
| 945 | |
| 946 | GlobalHandles::~GlobalHandles() { regular_nodes_.reset(nullptr); } |
| 947 | |
| 948 | Handle<Object> GlobalHandles::Create(Object value) { |
| 949 | GlobalHandles::Node* result = regular_nodes_->Acquire(value); |
| 950 | if (ObjectInYoungGeneration(value) && !result->is_in_young_list()) { |
| 951 | young_nodes_.push_back(result); |
| 952 | result->set_in_young_list(true); |
| 953 | } |
| 954 | return result->handle(); |
| 955 | } |
| 956 | |
| 957 | Handle<Object> GlobalHandles::Create(Address value) { |
| 958 | return Create(Object(value)); |
| 959 | } |
| 960 | |
| 961 | Handle<Object> GlobalHandles::CreateTraced(Object value, Address* slot, |
| 962 | GlobalHandleStoreMode store_mode) { |
| 963 | return CreateTraced( |
| 964 | value, slot, store_mode, |
| 965 | on_stack_nodes_->IsOnStack(reinterpret_cast<uintptr_t>(slot))); |
| 966 | } |
| 967 | |
| 968 | Handle<Object> GlobalHandles::CreateTraced(Object value, Address* slot, |
| 969 | GlobalHandleStoreMode store_mode, |
| 970 | bool is_on_stack) { |
| 971 | GlobalHandles::TracedNode* result; |
| 972 | if (is_on_stack) { |
| 973 | result = on_stack_nodes_->Acquire(value, reinterpret_cast<uintptr_t>(slot)); |
| 974 | } else { |
| 975 | result = traced_nodes_->Acquire(value); |
| 976 | if (ObjectInYoungGeneration(value) && !result->is_in_young_list()) { |
| 977 | traced_young_nodes_.push_back(result); |
| 978 | result->set_in_young_list(true); |
| 979 | } |
| 980 | // Nodes are black allocated for simplicity. |
| 981 | result->set_markbit(); |
| 982 | if (store_mode != GlobalHandleStoreMode::kInitializingStore) { |
| 983 | WriteBarrier::MarkingFromGlobalHandle(value); |
| 984 | } |
| 985 | } |
| 986 | result->set_parameter(nullptr); |
| 987 | return result->handle(); |
| 988 | } |
| 989 | |
| 990 | Handle<Object> GlobalHandles::CreateTraced(Address value, Address* slot, |
| 991 | GlobalHandleStoreMode store_mode) { |
| 992 | return CreateTraced(Object(value), slot, store_mode); |
| 993 | } |
| 994 | |
| 995 | Handle<Object> GlobalHandles::CopyGlobal(Address* location) { |
| 996 | DCHECK_NOT_NULL(location)((void) 0); |
| 997 | GlobalHandles* global_handles = |
| 998 | Node::FromLocation(location)->global_handles(); |
| 999 | #ifdef VERIFY_HEAP |
| 1000 | if (i::FLAG_verify_heap) { |
| 1001 | Object(*location).ObjectVerify(global_handles->isolate()); |
| 1002 | } |
| 1003 | #endif // VERIFY_HEAP |
| 1004 | return global_handles->Create(*location); |
| 1005 | } |
| 1006 | |
| 1007 | namespace { |
| 1008 | void SetSlotThreadSafe(Address** slot, Address* val) { |
| 1009 | reinterpret_cast<std::atomic<Address*>*>(slot)->store( |
| 1010 | val, std::memory_order_relaxed); |
| 1011 | } |
| 1012 | } // namespace |
| 1013 | |
| 1014 | // static |
| 1015 | void GlobalHandles::CopyTracedReference(const Address* const* from, |
| 1016 | Address** to) { |
| 1017 | DCHECK_NOT_NULL(*from)((void) 0); |
| 1018 | DCHECK_NULL(*to)((void) 0); |
| 1019 | const TracedNode* node = TracedNode::FromLocation(*from); |
| 1020 | GlobalHandles* global_handles = |
| 1021 | GlobalHandles::From(const_cast<TracedNode*>(node)); |
| 1022 | Handle<Object> o = global_handles->CreateTraced( |
| 1023 | node->object(), reinterpret_cast<Address*>(to), |
| 1024 | GlobalHandleStoreMode::kAssigningStore); |
| 1025 | SetSlotThreadSafe(to, o.location()); |
| 1026 | TracedNode::Verify(global_handles, from); |
| 1027 | TracedNode::Verify(global_handles, to); |
| 1028 | #ifdef VERIFY_HEAP |
| 1029 | if (i::FLAG_verify_heap) { |
| 1030 | Object(**to).ObjectVerify(global_handles->isolate()); |
| 1031 | } |
| 1032 | #endif // VERIFY_HEAP |
| 1033 | } |
| 1034 | |
| 1035 | void GlobalHandles::MoveGlobal(Address** from, Address** to) { |
| 1036 | DCHECK_NOT_NULL(*from)((void) 0); |
| 1037 | DCHECK_NOT_NULL(*to)((void) 0); |
| 1038 | DCHECK_EQ(*from, *to)((void) 0); |
| 1039 | Node* node = Node::FromLocation(*from); |
| 1040 | if (node->IsWeak() && node->IsPhantomResetHandle()) { |
| 1041 | node->set_parameter(to); |
| 1042 | } |
| 1043 | |
| 1044 | // - Strong handles do not require fixups. |
| 1045 | // - Weak handles with finalizers and callbacks are too general to fix up. For |
| 1046 | // those the callers need to ensure consistency. |
| 1047 | } |
| 1048 | |
| 1049 | void GlobalHandles::MoveTracedReference(Address** from, Address** to) { |
| 1050 | // Fast path for moving from an empty reference. |
| 1051 | if (!*from) { |
| 1052 | DestroyTracedReference(*to); |
| 1053 | SetSlotThreadSafe(to, nullptr); |
| 1054 | return; |
| 1055 | } |
| 1056 | |
| 1057 | // Determining whether from or to are on stack. |
| 1058 | TracedNode* from_node = TracedNode::FromLocation(*from); |
| 1059 | DCHECK(from_node->IsInUse())((void) 0); |
| 1060 | TracedNode* to_node = TracedNode::FromLocation(*to); |
| 1061 | GlobalHandles* global_handles = nullptr; |
| 1062 | #ifdef DEBUG |
| 1063 | global_handles = GlobalHandles::From(from_node); |
| 1064 | #endif // DEBUG |
| 1065 | bool from_on_stack = from_node->is_on_stack(); |
| 1066 | bool to_on_stack = false; |
| 1067 | if (!to_node) { |
| 1068 | // Figure out whether stack or heap to allow fast path for heap->heap move. |
| 1069 | global_handles = GlobalHandles::From(from_node); |
| 1070 | to_on_stack = global_handles->on_stack_nodes_->IsOnStack( |
| 1071 | reinterpret_cast<uintptr_t>(to)); |
| 1072 | } else { |
| 1073 | to_on_stack = to_node->is_on_stack(); |
| 1074 | } |
| 1075 | |
| 1076 | // Moving. |
| 1077 | if (from_on_stack || to_on_stack) { |
| 1078 | // Move involving a stack slot. |
| 1079 | if (!to_node) { |
| 1080 | DCHECK(global_handles)((void) 0); |
| 1081 | Handle<Object> o = global_handles->CreateTraced( |
| 1082 | from_node->object(), reinterpret_cast<Address*>(to), |
| 1083 | GlobalHandleStoreMode::kAssigningStore, to_on_stack); |
| 1084 | SetSlotThreadSafe(to, o.location()); |
| 1085 | to_node = TracedNode::FromLocation(*to); |
Value stored to 'to_node' is never read | |
| 1086 | DCHECK_IMPLIES(!to_node->is_on_stack(), to_node->markbit())((void) 0); |
| 1087 | } else { |
| 1088 | DCHECK(to_node->IsInUse())((void) 0); |
| 1089 | to_node->CopyObjectReference(*from_node); |
| 1090 | if (!to_node->is_on_stack() && !to_node->is_in_young_list() && |
| 1091 | ObjectInYoungGeneration(to_node->object())) { |
| 1092 | global_handles = GlobalHandles::From(from_node); |
| 1093 | global_handles->traced_young_nodes_.push_back(to_node); |
| 1094 | to_node->set_in_young_list(true); |
| 1095 | } |
| 1096 | if (!to_on_stack) { |
| 1097 | WriteBarrier::MarkingFromGlobalHandle(to_node->object()); |
| 1098 | } |
| 1099 | } |
| 1100 | DestroyTracedReference(*from); |
| 1101 | SetSlotThreadSafe(from, nullptr); |
| 1102 | } else { |
| 1103 | // Pure heap move. |
| 1104 | DestroyTracedReference(*to); |
| 1105 | SetSlotThreadSafe(to, *from); |
| 1106 | to_node = from_node; |
| 1107 | DCHECK_NOT_NULL(*from)((void) 0); |
| 1108 | DCHECK_NOT_NULL(*to)((void) 0); |
| 1109 | DCHECK_EQ(*from, *to)((void) 0); |
| 1110 | WriteBarrier::MarkingFromGlobalHandle(to_node->object()); |
| 1111 | SetSlotThreadSafe(from, nullptr); |
| 1112 | } |
| 1113 | TracedNode::Verify(global_handles, to); |
| 1114 | } |
| 1115 | |
| 1116 | // static |
| 1117 | GlobalHandles* GlobalHandles::From(const TracedNode* node) { |
| 1118 | return node->is_on_stack() |
| 1119 | ? OnStackTracedNodeSpace::GetGlobalHandles(node) |
| 1120 | : NodeBlock<TracedNode>::From(node)->global_handles(); |
| 1121 | } |
| 1122 | |
| 1123 | void GlobalHandles::MarkTraced(Address* location) { |
| 1124 | TracedNode* node = TracedNode::FromLocation(location); |
| 1125 | DCHECK(node->IsInUse())((void) 0); |
| 1126 | if (node->is_on_stack()) return; |
| 1127 | node->set_markbit(); |
| 1128 | } |
| 1129 | |
| 1130 | void GlobalHandles::Destroy(Address* location) { |
| 1131 | if (location != nullptr) { |
| 1132 | NodeSpace<Node>::Release(Node::FromLocation(location)); |
| 1133 | } |
| 1134 | } |
| 1135 | |
| 1136 | // static |
| 1137 | void GlobalHandles::DestroyTracedReference(Address* location) { |
| 1138 | if (location != nullptr) { |
| 1139 | TracedNode* node = TracedNode::FromLocation(location); |
| 1140 | if (node->is_on_stack()) { |
| 1141 | node->Release(nullptr); |
| 1142 | return; |
| 1143 | } |
| 1144 | DCHECK(!node->is_on_stack())((void) 0); |
| 1145 | |
| 1146 | auto* global_handles = GlobalHandles::From(node); |
| 1147 | // When marking is off the handle may be freed immediately. Note that this |
| 1148 | // includes also the case when invoking the first pass callbacks during the |
| 1149 | // atomic pause which requires releasing a node fully. |
| 1150 | if (!global_handles->is_marking_) { |
| 1151 | NodeSpace<TracedNode>::Release(node); |
| 1152 | return; |
| 1153 | } |
| 1154 | |
| 1155 | // Incremental marking is on. This also covers the scavenge case which |
| 1156 | // prohibits eagerly reclaiming nodes when marking is on during a scavenge. |
| 1157 | // |
| 1158 | // On-heap traced nodes are released in the atomic pause in |
| 1159 | // `IterateWeakRootsForPhantomHandles()` when they are discovered as not |
| 1160 | // marked. |
| 1161 | // |
| 1162 | // Eagerly clear out the object here to avoid needlessly marking it from |
| 1163 | // this point on. Also clear out callback and backreference for the version |
| 1164 | // with callbacks to avoid calling into possibly dead memory later. |
| 1165 | // |
| 1166 | // In the case this happens during incremental marking, the node may |
| 1167 | // still be spuriously marked as live and is then only reclaimed on the |
| 1168 | // next cycle. |
| 1169 | node->clear_object(); |
| 1170 | node->set_parameter(nullptr); |
| 1171 | } |
| 1172 | } |
| 1173 | |
| 1174 | using GenericCallback = v8::WeakCallbackInfo<void>::Callback; |
| 1175 | |
| 1176 | void GlobalHandles::MakeWeak(Address* location, void* parameter, |
| 1177 | GenericCallback phantom_callback, |
| 1178 | v8::WeakCallbackType type) { |
| 1179 | Node::FromLocation(location)->MakeWeak(parameter, phantom_callback, type); |
| 1180 | } |
| 1181 | |
| 1182 | void GlobalHandles::MakeWeak(Address** location_addr) { |
| 1183 | Node::FromLocation(*location_addr)->MakeWeak(location_addr); |
| 1184 | } |
| 1185 | |
| 1186 | void* GlobalHandles::ClearWeakness(Address* location) { |
| 1187 | return Node::FromLocation(location)->ClearWeakness(); |
| 1188 | } |
| 1189 | |
| 1190 | void GlobalHandles::AnnotateStrongRetainer(Address* location, |
| 1191 | const char* label) { |
| 1192 | Node::FromLocation(location)->AnnotateStrongRetainer(label); |
| 1193 | } |
| 1194 | |
| 1195 | bool GlobalHandles::IsWeak(Address* location) { |
| 1196 | return Node::FromLocation(location)->IsWeak(); |
| 1197 | } |
| 1198 | |
| 1199 | DISABLE_CFI_PERF__attribute__((no_sanitize("cfi"))) |
| 1200 | void GlobalHandles::IterateWeakRootsForFinalizers(RootVisitor* v) { |
| 1201 | for (Node* node : *regular_nodes_) { |
| 1202 | if (node->IsWeakRetainer() && node->state() == Node::PENDING) { |
| 1203 | DCHECK(!node->IsPhantomCallback())((void) 0); |
| 1204 | DCHECK(!node->IsPhantomResetHandle())((void) 0); |
| 1205 | // Finalizers need to survive. |
| 1206 | v->VisitRootPointer(Root::kGlobalHandles, node->label(), |
| 1207 | node->location()); |
| 1208 | } |
| 1209 | } |
| 1210 | } |
| 1211 | |
| 1212 | DISABLE_CFI_PERF__attribute__((no_sanitize("cfi"))) |
| 1213 | void GlobalHandles::IterateWeakRootsForPhantomHandles( |
| 1214 | WeakSlotCallbackWithHeap should_reset_handle) { |
| 1215 | for (Node* node : *regular_nodes_) { |
| 1216 | if (node->IsWeakRetainer() && |
| 1217 | should_reset_handle(isolate()->heap(), node->location())) { |
| 1218 | if (node->IsPhantomResetHandle()) { |
| 1219 | node->MarkPending(); |
| 1220 | node->ResetPhantomHandle(); |
| 1221 | ++number_of_phantom_handle_resets_; |
| 1222 | } else if (node->IsPhantomCallback()) { |
| 1223 | node->MarkPending(); |
| 1224 | node->CollectPhantomCallbackData(®ular_pending_phantom_callbacks_); |
| 1225 | } |
| 1226 | } |
| 1227 | } |
| 1228 | for (TracedNode* node : *traced_nodes_) { |
| 1229 | if (!node->IsInUse()) continue; |
| 1230 | // Detect unreachable nodes first. |
| 1231 | if (!node->markbit()) { |
| 1232 | // The handle itself is unreachable. We can clear it even if the target V8 |
| 1233 | // object is alive. |
| 1234 | node->ResetPhantomHandle(); |
| 1235 | ++number_of_phantom_handle_resets_; |
| 1236 | continue; |
| 1237 | } |
| 1238 | // Clear the markbit for the next GC. |
| 1239 | node->clear_markbit(); |
| 1240 | DCHECK(node->IsInUse())((void) 0); |
| 1241 | // Detect nodes with unreachable target objects. |
| 1242 | if (should_reset_handle(isolate()->heap(), node->location())) { |
| 1243 | node->ResetPhantomHandle(); |
| 1244 | ++number_of_phantom_handle_resets_; |
| 1245 | } |
| 1246 | } |
| 1247 | } |
| 1248 | |
| 1249 | void GlobalHandles::IterateWeakRootsIdentifyFinalizers( |
| 1250 | WeakSlotCallbackWithHeap should_reset_handle) { |
| 1251 | for (Node* node : *regular_nodes_) { |
| 1252 | if (node->IsWeak() && |
| 1253 | should_reset_handle(isolate()->heap(), node->location())) { |
| 1254 | if (node->IsFinalizerHandle()) { |
| 1255 | node->MarkPending(); |
| 1256 | } |
| 1257 | } |
| 1258 | } |
| 1259 | } |
| 1260 | |
| 1261 | void GlobalHandles::IdentifyWeakUnmodifiedObjects( |
| 1262 | WeakSlotCallback is_unmodified) { |
| 1263 | if (!FLAG_reclaim_unmodified_wrappers) return; |
| 1264 | |
| 1265 | // Treat all objects as roots during incremental marking to avoid corrupting |
| 1266 | // marking worklists. |
| 1267 | if (isolate()->heap()->incremental_marking()->IsMarking()) return; |
| 1268 | |
| 1269 | auto* const handler = isolate()->heap()->GetEmbedderRootsHandler(); |
| 1270 | for (TracedNode* node : traced_young_nodes_) { |
| 1271 | if (node->IsInUse()) { |
| 1272 | DCHECK(node->is_root())((void) 0); |
| 1273 | if (is_unmodified(node->location())) { |
| 1274 | v8::Value* value = ToApi<v8::Value>(node->handle()); |
| 1275 | node->set_root(handler->IsRoot( |
| 1276 | *reinterpret_cast<v8::TracedReference<v8::Value>*>(&value))); |
| 1277 | } |
| 1278 | } |
| 1279 | } |
| 1280 | } |
| 1281 | |
| 1282 | void GlobalHandles::IterateYoungStrongAndDependentRoots(RootVisitor* v) { |
| 1283 | for (Node* node : young_nodes_) { |
| 1284 | if (node->IsStrongRetainer()) { |
| 1285 | v->VisitRootPointer(Root::kGlobalHandles, node->label(), |
| 1286 | node->location()); |
| 1287 | } |
| 1288 | } |
| 1289 | for (TracedNode* node : traced_young_nodes_) { |
| 1290 | if (node->IsInUse() && node->is_root()) { |
| 1291 | v->VisitRootPointer(Root::kGlobalHandles, nullptr, node->location()); |
| 1292 | } |
| 1293 | } |
| 1294 | } |
| 1295 | |
| 1296 | void GlobalHandles::MarkYoungWeakDeadObjectsPending( |
| 1297 | WeakSlotCallbackWithHeap is_dead) { |
| 1298 | for (Node* node : young_nodes_) { |
| 1299 | DCHECK(node->is_in_young_list())((void) 0); |
| 1300 | if (node->IsWeak() && is_dead(isolate_->heap(), node->location())) { |
| 1301 | if (!node->IsPhantomCallback() && !node->IsPhantomResetHandle()) { |
| 1302 | node->MarkPending(); |
| 1303 | } |
| 1304 | } |
| 1305 | } |
| 1306 | } |
| 1307 | |
| 1308 | void GlobalHandles::IterateYoungWeakDeadObjectsForFinalizers(RootVisitor* v) { |
| 1309 | for (Node* node : young_nodes_) { |
| 1310 | DCHECK(node->is_in_young_list())((void) 0); |
| 1311 | if (node->IsWeakRetainer() && (node->state() == Node::PENDING)) { |
| 1312 | DCHECK(!node->IsPhantomCallback())((void) 0); |
| 1313 | DCHECK(!node->IsPhantomResetHandle())((void) 0); |
| 1314 | // Finalizers need to survive. |
| 1315 | v->VisitRootPointer(Root::kGlobalHandles, node->label(), |
| 1316 | node->location()); |
| 1317 | } |
| 1318 | } |
| 1319 | } |
| 1320 | |
| 1321 | void GlobalHandles::IterateYoungWeakObjectsForPhantomHandles( |
| 1322 | RootVisitor* v, WeakSlotCallbackWithHeap should_reset_handle) { |
| 1323 | for (Node* node : young_nodes_) { |
| 1324 | DCHECK(node->is_in_young_list())((void) 0); |
| 1325 | if (node->IsWeakRetainer() && (node->state() != Node::PENDING)) { |
| 1326 | if (should_reset_handle(isolate_->heap(), node->location())) { |
| 1327 | DCHECK(node->IsPhantomResetHandle() || node->IsPhantomCallback())((void) 0); |
| 1328 | if (node->IsPhantomResetHandle()) { |
| 1329 | node->MarkPending(); |
| 1330 | node->ResetPhantomHandle(); |
| 1331 | ++number_of_phantom_handle_resets_; |
| 1332 | } else if (node->IsPhantomCallback()) { |
| 1333 | node->MarkPending(); |
| 1334 | node->CollectPhantomCallbackData(®ular_pending_phantom_callbacks_); |
| 1335 | } else { |
| 1336 | UNREACHABLE()V8_Fatal("unreachable code"); |
| 1337 | } |
| 1338 | } else { |
| 1339 | // Node survived and needs to be visited. |
| 1340 | v->VisitRootPointer(Root::kGlobalHandles, node->label(), |
| 1341 | node->location()); |
| 1342 | } |
| 1343 | } |
| 1344 | } |
| 1345 | |
| 1346 | if (!FLAG_reclaim_unmodified_wrappers) return; |
| 1347 | |
| 1348 | auto* const handler = isolate()->heap()->GetEmbedderRootsHandler(); |
| 1349 | for (TracedNode* node : traced_young_nodes_) { |
| 1350 | if (!node->IsInUse()) continue; |
| 1351 | |
| 1352 | DCHECK_IMPLIES(node->is_root(),((void) 0) |
| 1353 | !should_reset_handle(isolate_->heap(), node->location()))((void) 0); |
| 1354 | if (should_reset_handle(isolate_->heap(), node->location())) { |
| 1355 | v8::Value* value = ToApi<v8::Value>(node->handle()); |
| 1356 | handler->ResetRoot( |
| 1357 | *reinterpret_cast<v8::TracedReference<v8::Value>*>(&value)); |
| 1358 | // We cannot check whether a node is in use here as the reset behavior |
| 1359 | // depends on whether incremental marking is running when reclaiming |
| 1360 | // young objects. |
| 1361 | ++number_of_phantom_handle_resets_; |
| 1362 | } else { |
| 1363 | if (!node->is_root()) { |
| 1364 | node->set_root(true); |
| 1365 | v->VisitRootPointer(Root::kGlobalHandles, nullptr, node->location()); |
| 1366 | } |
| 1367 | } |
| 1368 | } |
| 1369 | } |
| 1370 | |
| 1371 | void GlobalHandles::InvokeSecondPassPhantomCallbacksFromTask() { |
| 1372 | DCHECK(second_pass_callbacks_task_posted_)((void) 0); |
| 1373 | second_pass_callbacks_task_posted_ = false; |
| 1374 | Heap::DevToolsTraceEventScope devtools_trace_event_scope( |
| 1375 | isolate()->heap(), "MajorGC", "invoke weak phantom callbacks"); |
| 1376 | TRACE_EVENT0("v8", "V8.GCPhantomHandleProcessingCallback")static v8::base::AtomicWord trace_event_unique_atomic1376 = 0 ; const uint8_t* trace_event_unique_category_group_enabled1376 ; trace_event_unique_category_group_enabled1376 = reinterpret_cast <const uint8_t*>(v8::base::Relaxed_Load(&(trace_event_unique_atomic1376 ))); if (!trace_event_unique_category_group_enabled1376) { trace_event_unique_category_group_enabled1376 = v8::internal::tracing::TraceEventHelper::GetTracingController () ->GetCategoryGroupEnabled("v8"); v8::base::Relaxed_Store (&(trace_event_unique_atomic1376), (reinterpret_cast<v8 ::base::AtomicWord>( trace_event_unique_category_group_enabled1376 ))); };; v8::internal::tracing::ScopedTracer trace_event_unique_tracer1376 ; if (v8::base::Relaxed_Load(reinterpret_cast<const v8::base ::Atomic8*>( trace_event_unique_category_group_enabled1376 )) & (kEnabledForRecording_CategoryGroupEnabledFlags | kEnabledForEventCallback_CategoryGroupEnabledFlags )) { uint64_t h = v8::internal::tracing::AddTraceEvent( ('X') , trace_event_unique_category_group_enabled1376, "V8.GCPhantomHandleProcessingCallback" , v8::internal::tracing::kGlobalScope, v8::internal::tracing:: kNoId, v8::internal::tracing::kNoId, (static_cast<unsigned int>(0))); trace_event_unique_tracer1376 .Initialize(trace_event_unique_category_group_enabled1376 , "V8.GCPhantomHandleProcessingCallback", h); }; |
| 1377 | isolate()->heap()->CallGCPrologueCallbacks( |
| 1378 | GCType::kGCTypeProcessWeakCallbacks, kNoGCCallbackFlags); |
| 1379 | InvokeSecondPassPhantomCallbacks(); |
| 1380 | isolate()->heap()->CallGCEpilogueCallbacks( |
| 1381 | GCType::kGCTypeProcessWeakCallbacks, kNoGCCallbackFlags); |
| 1382 | } |
| 1383 | |
| 1384 | void GlobalHandles::InvokeSecondPassPhantomCallbacks() { |
| 1385 | // The callbacks may execute JS, which in turn may lead to another GC run. |
| 1386 | // If we are already processing the callbacks, we do not want to start over |
| 1387 | // from within the inner GC. Newly added callbacks will always be run by the |
| 1388 | // outermost GC run only. |
| 1389 | if (running_second_pass_callbacks_) return; |
| 1390 | running_second_pass_callbacks_ = true; |
| 1391 | |
| 1392 | AllowJavascriptExecution allow_js(isolate()); |
| 1393 | while (!second_pass_callbacks_.empty()) { |
| 1394 | auto callback = second_pass_callbacks_.back(); |
| 1395 | second_pass_callbacks_.pop_back(); |
| 1396 | callback.Invoke(isolate(), PendingPhantomCallback::kSecondPass); |
| 1397 | } |
| 1398 | running_second_pass_callbacks_ = false; |
| 1399 | } |
| 1400 | |
| 1401 | size_t GlobalHandles::PostScavengeProcessing(unsigned post_processing_count) { |
| 1402 | size_t freed_nodes = 0; |
| 1403 | for (Node* node : young_nodes_) { |
| 1404 | // Filter free nodes. |
| 1405 | if (!node->IsRetainer()) continue; |
| 1406 | |
| 1407 | if (node->IsPending()) { |
| 1408 | DCHECK(node->has_callback())((void) 0); |
| 1409 | DCHECK(node->IsPendingFinalizer())((void) 0); |
| 1410 | node->PostGarbageCollectionProcessing(isolate_); |
| 1411 | } |
| 1412 | if (InRecursiveGC(post_processing_count)) return freed_nodes; |
| 1413 | |
| 1414 | if (!node->IsRetainer()) freed_nodes++; |
| 1415 | } |
| 1416 | return freed_nodes; |
| 1417 | } |
| 1418 | |
| 1419 | size_t GlobalHandles::PostMarkSweepProcessing(unsigned post_processing_count) { |
| 1420 | size_t freed_nodes = 0; |
| 1421 | for (Node* node : *regular_nodes_) { |
| 1422 | // Filter free nodes. |
| 1423 | if (!node->IsRetainer()) continue; |
| 1424 | |
| 1425 | if (node->IsPending()) { |
| 1426 | DCHECK(node->has_callback())((void) 0); |
| 1427 | DCHECK(node->IsPendingFinalizer())((void) 0); |
| 1428 | node->PostGarbageCollectionProcessing(isolate_); |
| 1429 | } |
| 1430 | if (InRecursiveGC(post_processing_count)) return freed_nodes; |
| 1431 | |
| 1432 | if (!node->IsRetainer()) freed_nodes++; |
| 1433 | } |
| 1434 | return freed_nodes; |
| 1435 | } |
| 1436 | |
| 1437 | template <typename T> |
| 1438 | void GlobalHandles::UpdateAndCompactListOfYoungNode( |
| 1439 | std::vector<T*>* node_list) { |
| 1440 | size_t last = 0; |
| 1441 | for (T* node : *node_list) { |
| 1442 | DCHECK(node->is_in_young_list())((void) 0); |
| 1443 | if (node->IsInUse()) { |
| 1444 | if (ObjectInYoungGeneration(node->object())) { |
| 1445 | (*node_list)[last++] = node; |
| 1446 | isolate_->heap()->IncrementNodesCopiedInNewSpace(); |
| 1447 | } else { |
| 1448 | node->set_in_young_list(false); |
| 1449 | isolate_->heap()->IncrementNodesPromoted(); |
| 1450 | } |
| 1451 | } else { |
| 1452 | node->set_in_young_list(false); |
| 1453 | isolate_->heap()->IncrementNodesDiedInNewSpace(); |
| 1454 | } |
| 1455 | } |
| 1456 | DCHECK_LE(last, node_list->size())((void) 0); |
| 1457 | node_list->resize(last); |
| 1458 | node_list->shrink_to_fit(); |
| 1459 | } |
| 1460 | |
| 1461 | void GlobalHandles::UpdateListOfYoungNodes() { |
| 1462 | UpdateAndCompactListOfYoungNode(&young_nodes_); |
| 1463 | UpdateAndCompactListOfYoungNode(&traced_young_nodes_); |
| 1464 | } |
| 1465 | |
| 1466 | template <typename T> |
| 1467 | size_t GlobalHandles::InvokeFirstPassWeakCallbacks( |
| 1468 | std::vector<std::pair<T*, PendingPhantomCallback>>* pending) { |
| 1469 | size_t freed_nodes = 0; |
| 1470 | std::vector<std::pair<T*, PendingPhantomCallback>> pending_phantom_callbacks; |
| 1471 | pending_phantom_callbacks.swap(*pending); |
| 1472 | { |
| 1473 | // The initial pass callbacks must simply clear the nodes. |
| 1474 | for (auto& pair : pending_phantom_callbacks) { |
| 1475 | T* node = pair.first; |
| 1476 | DCHECK_EQ(T::NEAR_DEATH, node->state())((void) 0); |
| 1477 | pair.second.Invoke(isolate(), PendingPhantomCallback::kFirstPass); |
| 1478 | |
| 1479 | // Transition to second pass. It is required that the first pass callback |
| 1480 | // resets the handle using |v8::PersistentBase::Reset|. Also see comments |
| 1481 | // on |v8::WeakCallbackInfo|. |
| 1482 | CHECK_WITH_MSG(T::FREE == node->state(),do { if ((__builtin_expect(!!(!(T::FREE == node->state())) , 0))) { V8_Fatal("Check failed: %s.", "Handle not reset in first callback. See comments on " "|v8::WeakCallbackInfo|."); } } while (false) |
| 1483 | "Handle not reset in first callback. See comments on "do { if ((__builtin_expect(!!(!(T::FREE == node->state())) , 0))) { V8_Fatal("Check failed: %s.", "Handle not reset in first callback. See comments on " "|v8::WeakCallbackInfo|."); } } while (false) |
| 1484 | "|v8::WeakCallbackInfo|.")do { if ((__builtin_expect(!!(!(T::FREE == node->state())) , 0))) { V8_Fatal("Check failed: %s.", "Handle not reset in first callback. See comments on " "|v8::WeakCallbackInfo|."); } } while (false); |
| 1485 | |
| 1486 | if (pair.second.callback()) second_pass_callbacks_.push_back(pair.second); |
| 1487 | freed_nodes++; |
| 1488 | } |
| 1489 | } |
| 1490 | return freed_nodes; |
| 1491 | } |
| 1492 | |
| 1493 | size_t GlobalHandles::InvokeFirstPassWeakCallbacks() { |
| 1494 | return InvokeFirstPassWeakCallbacks(®ular_pending_phantom_callbacks_) + |
| 1495 | InvokeFirstPassWeakCallbacks(&traced_pending_phantom_callbacks_); |
| 1496 | } |
| 1497 | |
| 1498 | void GlobalHandles::InvokeOrScheduleSecondPassPhantomCallbacks( |
| 1499 | bool synchronous_second_pass) { |
| 1500 | if (!second_pass_callbacks_.empty()) { |
| 1501 | if (FLAG_optimize_for_size || FLAG_predictable || synchronous_second_pass) { |
| 1502 | Heap::DevToolsTraceEventScope devtools_trace_event_scope( |
| 1503 | isolate()->heap(), "MajorGC", "invoke weak phantom callbacks"); |
| 1504 | isolate()->heap()->CallGCPrologueCallbacks( |
| 1505 | GCType::kGCTypeProcessWeakCallbacks, kNoGCCallbackFlags); |
| 1506 | InvokeSecondPassPhantomCallbacks(); |
| 1507 | isolate()->heap()->CallGCEpilogueCallbacks( |
| 1508 | GCType::kGCTypeProcessWeakCallbacks, kNoGCCallbackFlags); |
| 1509 | } else if (!second_pass_callbacks_task_posted_) { |
| 1510 | second_pass_callbacks_task_posted_ = true; |
| 1511 | auto taskrunner = V8::GetCurrentPlatform()->GetForegroundTaskRunner( |
| 1512 | reinterpret_cast<v8::Isolate*>(isolate())); |
| 1513 | taskrunner->PostTask(MakeCancelableTask( |
| 1514 | isolate(), [this] { InvokeSecondPassPhantomCallbacksFromTask(); })); |
| 1515 | } |
| 1516 | } |
| 1517 | } |
| 1518 | |
| 1519 | void GlobalHandles::PendingPhantomCallback::Invoke(Isolate* isolate, |
| 1520 | InvocationType type) { |
| 1521 | Data::Callback* callback_addr = nullptr; |
| 1522 | if (type == kFirstPass) { |
| 1523 | callback_addr = &callback_; |
| 1524 | } |
| 1525 | Data data(reinterpret_cast<v8::Isolate*>(isolate), parameter_, |
| 1526 | embedder_fields_, callback_addr); |
| 1527 | Data::Callback callback = callback_; |
| 1528 | callback_ = nullptr; |
| 1529 | callback(data); |
| 1530 | } |
| 1531 | |
| 1532 | bool GlobalHandles::InRecursiveGC(unsigned gc_processing_counter) { |
| 1533 | return gc_processing_counter != post_gc_processing_count_; |
| 1534 | } |
| 1535 | |
| 1536 | size_t GlobalHandles::PostGarbageCollectionProcessing( |
| 1537 | GarbageCollector collector, const v8::GCCallbackFlags gc_callback_flags) { |
| 1538 | // Process weak global handle callbacks. This must be done after the |
| 1539 | // GC is completely done, because the callbacks may invoke arbitrary |
| 1540 | // API functions. |
| 1541 | DCHECK_EQ(Heap::NOT_IN_GC, isolate_->heap()->gc_state())((void) 0); |
| 1542 | const unsigned post_processing_count = ++post_gc_processing_count_; |
| 1543 | size_t freed_nodes = 0; |
| 1544 | bool synchronous_second_pass = |
| 1545 | isolate_->heap()->IsTearingDown() || |
| 1546 | (gc_callback_flags & |
| 1547 | (kGCCallbackFlagForced | kGCCallbackFlagCollectAllAvailableGarbage | |
| 1548 | kGCCallbackFlagSynchronousPhantomCallbackProcessing)) != 0; |
| 1549 | InvokeOrScheduleSecondPassPhantomCallbacks(synchronous_second_pass); |
| 1550 | if (InRecursiveGC(post_processing_count)) return freed_nodes; |
| 1551 | |
| 1552 | freed_nodes += Heap::IsYoungGenerationCollector(collector) |
| 1553 | ? PostScavengeProcessing(post_processing_count) |
| 1554 | : PostMarkSweepProcessing(post_processing_count); |
| 1555 | if (InRecursiveGC(post_processing_count)) return freed_nodes; |
| 1556 | |
| 1557 | UpdateListOfYoungNodes(); |
| 1558 | return freed_nodes; |
| 1559 | } |
| 1560 | |
| 1561 | void GlobalHandles::IterateStrongRoots(RootVisitor* v) { |
| 1562 | for (Node* node : *regular_nodes_) { |
| 1563 | if (node->IsStrongRetainer()) { |
| 1564 | v->VisitRootPointer(Root::kGlobalHandles, node->label(), |
| 1565 | node->location()); |
| 1566 | } |
| 1567 | } |
| 1568 | } |
| 1569 | |
| 1570 | void GlobalHandles::IterateStrongStackRoots(RootVisitor* v) { |
| 1571 | on_stack_nodes_->Iterate(v); |
| 1572 | } |
| 1573 | |
| 1574 | void GlobalHandles::IterateWeakRoots(RootVisitor* v) { |
| 1575 | for (Node* node : *regular_nodes_) { |
| 1576 | if (node->IsWeak()) { |
| 1577 | v->VisitRootPointer(Root::kGlobalHandles, node->label(), |
| 1578 | node->location()); |
| 1579 | } |
| 1580 | } |
| 1581 | for (TracedNode* node : *traced_nodes_) { |
| 1582 | if (node->IsInUse()) { |
| 1583 | v->VisitRootPointer(Root::kGlobalHandles, nullptr, node->location()); |
| 1584 | } |
| 1585 | } |
| 1586 | } |
| 1587 | |
| 1588 | DISABLE_CFI_PERF__attribute__((no_sanitize("cfi"))) |
| 1589 | void GlobalHandles::IterateAllRoots(RootVisitor* v) { |
| 1590 | for (Node* node : *regular_nodes_) { |
| 1591 | if (node->IsRetainer()) { |
| 1592 | v->VisitRootPointer(Root::kGlobalHandles, node->label(), |
| 1593 | node->location()); |
| 1594 | } |
| 1595 | } |
| 1596 | for (TracedNode* node : *traced_nodes_) { |
| 1597 | if (node->IsRetainer()) { |
| 1598 | v->VisitRootPointer(Root::kGlobalHandles, nullptr, node->location()); |
| 1599 | } |
| 1600 | } |
| 1601 | on_stack_nodes_->Iterate(v); |
| 1602 | } |
| 1603 | |
| 1604 | DISABLE_CFI_PERF__attribute__((no_sanitize("cfi"))) |
| 1605 | void GlobalHandles::IterateAllYoungRoots(RootVisitor* v) { |
| 1606 | for (Node* node : young_nodes_) { |
| 1607 | if (node->IsRetainer()) { |
| 1608 | v->VisitRootPointer(Root::kGlobalHandles, node->label(), |
| 1609 | node->location()); |
| 1610 | } |
| 1611 | } |
| 1612 | for (TracedNode* node : traced_young_nodes_) { |
| 1613 | if (node->IsRetainer()) { |
| 1614 | v->VisitRootPointer(Root::kGlobalHandles, nullptr, node->location()); |
| 1615 | } |
| 1616 | } |
| 1617 | on_stack_nodes_->Iterate(v); |
| 1618 | } |
| 1619 | |
| 1620 | DISABLE_CFI_PERF__attribute__((no_sanitize("cfi"))) |
| 1621 | void GlobalHandles::ApplyPersistentHandleVisitor( |
| 1622 | v8::PersistentHandleVisitor* visitor, GlobalHandles::Node* node) { |
| 1623 | v8::Value* value = ToApi<v8::Value>(node->handle()); |
| 1624 | visitor->VisitPersistentHandle( |
| 1625 | reinterpret_cast<v8::Persistent<v8::Value>*>(&value), |
| 1626 | node->wrapper_class_id()); |
| 1627 | } |
| 1628 | |
| 1629 | DISABLE_CFI_PERF__attribute__((no_sanitize("cfi"))) |
| 1630 | void GlobalHandles::IterateAllRootsWithClassIds( |
| 1631 | v8::PersistentHandleVisitor* visitor) { |
| 1632 | for (Node* node : *regular_nodes_) { |
| 1633 | if (node->IsRetainer() && node->has_wrapper_class_id()) { |
| 1634 | ApplyPersistentHandleVisitor(visitor, node); |
| 1635 | } |
| 1636 | } |
| 1637 | } |
| 1638 | |
| 1639 | DISABLE_CFI_PERF__attribute__((no_sanitize("cfi"))) |
| 1640 | void GlobalHandles::IterateTracedNodes( |
| 1641 | v8::EmbedderHeapTracer::TracedGlobalHandleVisitor* visitor) { |
| 1642 | for (TracedNode* node : *traced_nodes_) { |
| 1643 | if (node->IsInUse()) { |
| 1644 | v8::Value* value = ToApi<v8::Value>(node->handle()); |
| 1645 | visitor->VisitTracedReference( |
| 1646 | *reinterpret_cast<v8::TracedReference<v8::Value>*>(&value)); |
| 1647 | } |
| 1648 | } |
| 1649 | } |
| 1650 | |
| 1651 | DISABLE_CFI_PERF__attribute__((no_sanitize("cfi"))) |
| 1652 | void GlobalHandles::IterateAllYoungRootsWithClassIds( |
| 1653 | v8::PersistentHandleVisitor* visitor) { |
| 1654 | for (Node* node : young_nodes_) { |
| 1655 | if (node->IsRetainer() && node->has_wrapper_class_id()) { |
| 1656 | ApplyPersistentHandleVisitor(visitor, node); |
| 1657 | } |
| 1658 | } |
| 1659 | } |
| 1660 | |
| 1661 | DISABLE_CFI_PERF__attribute__((no_sanitize("cfi"))) |
| 1662 | void GlobalHandles::IterateYoungWeakRootsWithClassIds( |
| 1663 | v8::PersistentHandleVisitor* visitor) { |
| 1664 | for (Node* node : young_nodes_) { |
| 1665 | if (node->has_wrapper_class_id() && node->IsWeak()) { |
| 1666 | ApplyPersistentHandleVisitor(visitor, node); |
| 1667 | } |
| 1668 | } |
| 1669 | } |
| 1670 | |
| 1671 | void GlobalHandles::RecordStats(HeapStats* stats) { |
| 1672 | *stats->global_handle_count = 0; |
| 1673 | *stats->weak_global_handle_count = 0; |
| 1674 | *stats->pending_global_handle_count = 0; |
| 1675 | *stats->near_death_global_handle_count = 0; |
| 1676 | *stats->free_global_handle_count = 0; |
| 1677 | for (Node* node : *regular_nodes_) { |
| 1678 | *stats->global_handle_count += 1; |
| 1679 | if (node->state() == Node::WEAK) { |
| 1680 | *stats->weak_global_handle_count += 1; |
| 1681 | } else if (node->state() == Node::PENDING) { |
| 1682 | *stats->pending_global_handle_count += 1; |
| 1683 | } else if (node->state() == Node::NEAR_DEATH) { |
| 1684 | *stats->near_death_global_handle_count += 1; |
| 1685 | } else if (node->state() == Node::FREE) { |
| 1686 | *stats->free_global_handle_count += 1; |
| 1687 | } |
| 1688 | } |
| 1689 | } |
| 1690 | |
| 1691 | #ifdef DEBUG |
| 1692 | |
| 1693 | void GlobalHandles::PrintStats() { |
| 1694 | int total = 0; |
| 1695 | int weak = 0; |
| 1696 | int pending = 0; |
| 1697 | int near_death = 0; |
| 1698 | int destroyed = 0; |
| 1699 | |
| 1700 | for (Node* node : *regular_nodes_) { |
| 1701 | total++; |
| 1702 | if (node->state() == Node::WEAK) weak++; |
| 1703 | if (node->state() == Node::PENDING) pending++; |
| 1704 | if (node->state() == Node::NEAR_DEATH) near_death++; |
| 1705 | if (node->state() == Node::FREE) destroyed++; |
| 1706 | } |
| 1707 | |
| 1708 | PrintF("Global Handle Statistics:\n"); |
| 1709 | PrintF(" allocated memory = %zuB\n", total * sizeof(Node)); |
| 1710 | PrintF(" # weak = %d\n", weak); |
| 1711 | PrintF(" # pending = %d\n", pending); |
| 1712 | PrintF(" # near_death = %d\n", near_death); |
| 1713 | PrintF(" # free = %d\n", destroyed); |
| 1714 | PrintF(" # total = %d\n", total); |
| 1715 | } |
| 1716 | |
| 1717 | void GlobalHandles::Print() { |
| 1718 | PrintF("Global handles:\n"); |
| 1719 | for (Node* node : *regular_nodes_) { |
| 1720 | PrintF(" handle %p to %p%s\n", node->location().ToVoidPtr(), |
| 1721 | reinterpret_cast<void*>(node->object().ptr()), |
| 1722 | node->IsWeak() ? " (weak)" : ""); |
| 1723 | } |
| 1724 | } |
| 1725 | |
| 1726 | #endif |
| 1727 | |
| 1728 | EternalHandles::~EternalHandles() { |
| 1729 | for (Address* block : blocks_) delete[] block; |
| 1730 | } |
| 1731 | |
| 1732 | void EternalHandles::IterateAllRoots(RootVisitor* visitor) { |
| 1733 | int limit = size_; |
| 1734 | for (Address* block : blocks_) { |
| 1735 | DCHECK_GT(limit, 0)((void) 0); |
| 1736 | visitor->VisitRootPointers( |
| 1737 | Root::kEternalHandles, nullptr, FullObjectSlot(block), |
| 1738 | FullObjectSlot(block + std::min({limit, kSize}))); |
| 1739 | limit -= kSize; |
| 1740 | } |
| 1741 | } |
| 1742 | |
| 1743 | void EternalHandles::IterateYoungRoots(RootVisitor* visitor) { |
| 1744 | for (int index : young_node_indices_) { |
| 1745 | visitor->VisitRootPointer(Root::kEternalHandles, nullptr, |
| 1746 | FullObjectSlot(GetLocation(index))); |
| 1747 | } |
| 1748 | } |
| 1749 | |
| 1750 | void EternalHandles::PostGarbageCollectionProcessing() { |
| 1751 | size_t last = 0; |
| 1752 | for (int index : young_node_indices_) { |
| 1753 | if (ObjectInYoungGeneration(Object(*GetLocation(index)))) { |
| 1754 | young_node_indices_[last++] = index; |
| 1755 | } |
| 1756 | } |
| 1757 | DCHECK_LE(last, young_node_indices_.size())((void) 0); |
| 1758 | young_node_indices_.resize(last); |
| 1759 | } |
| 1760 | |
| 1761 | void EternalHandles::Create(Isolate* isolate, Object object, int* index) { |
| 1762 | DCHECK_EQ(kInvalidIndex, *index)((void) 0); |
| 1763 | if (object == Object()) return; |
| 1764 | Object the_hole = ReadOnlyRoots(isolate).the_hole_value(); |
| 1765 | DCHECK_NE(the_hole, object)((void) 0); |
| 1766 | int block = size_ >> kShift; |
| 1767 | int offset = size_ & kMask; |
| 1768 | // Need to resize. |
| 1769 | if (offset == 0) { |
| 1770 | Address* next_block = new Address[kSize]; |
| 1771 | MemsetPointer(FullObjectSlot(next_block), the_hole, kSize); |
| 1772 | blocks_.push_back(next_block); |
| 1773 | } |
| 1774 | DCHECK_EQ(the_hole.ptr(), blocks_[block][offset])((void) 0); |
| 1775 | blocks_[block][offset] = object.ptr(); |
| 1776 | if (ObjectInYoungGeneration(object)) { |
| 1777 | young_node_indices_.push_back(size_); |
| 1778 | } |
| 1779 | *index = size_++; |
| 1780 | } |
| 1781 | |
| 1782 | } // namespace internal |
| 1783 | } // namespace v8 |