| // Copyright 2016 the V8 project authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef V8_REMEMBERED_SET_H |
| #define V8_REMEMBERED_SET_H |
| |
| #include "src/heap/heap.h" |
| #include "src/heap/slot-set.h" |
| #include "src/heap/spaces.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| enum PointerDirection { OLD_TO_OLD, OLD_TO_NEW }; |
| |
| template <PointerDirection direction> |
| class RememberedSet { |
| public: |
| // Given a page and a slot in that page, this function adds the slot to the |
| // remembered set. |
| static void Insert(Page* page, Address slot_addr) { |
| DCHECK(page->Contains(slot_addr)); |
| SlotSet* slot_set = GetSlotSet(page); |
| if (slot_set == nullptr) { |
| slot_set = AllocateSlotSet(page); |
| } |
| uintptr_t offset = slot_addr - page->address(); |
| slot_set[offset / Page::kPageSize].Insert(offset % Page::kPageSize); |
| } |
| |
| // Given a page and a slot in that page, this function removes the slot from |
| // the remembered set. |
| // If the slot was never added, then the function does nothing. |
| static void Remove(Page* page, Address slot_addr) { |
| DCHECK(page->Contains(slot_addr)); |
| SlotSet* slot_set = GetSlotSet(page); |
| if (slot_set != nullptr) { |
| uintptr_t offset = slot_addr - page->address(); |
| slot_set[offset / Page::kPageSize].Remove(offset % Page::kPageSize); |
| } |
| } |
| |
| // Given a page and a range of slots in that page, this function removes the |
| // slots from the remembered set. |
| static void RemoveRange(Page* page, Address start, Address end) { |
| SlotSet* slot_set = GetSlotSet(page); |
| if (slot_set != nullptr) { |
| uintptr_t start_offset = start - page->address(); |
| uintptr_t end_offset = end - page->address(); |
| DCHECK_LT(start_offset, end_offset); |
| DCHECK_LE(end_offset, static_cast<uintptr_t>(Page::kPageSize)); |
| slot_set->RemoveRange(static_cast<uint32_t>(start_offset), |
| static_cast<uint32_t>(end_offset)); |
| } |
| } |
| |
| // Iterates and filters the remembered set with the given callback. |
| // The callback should take (Address slot) and return SlotCallbackResult. |
| template <typename Callback> |
| static void Iterate(Heap* heap, Callback callback) { |
| IterateMemoryChunks( |
| heap, [callback](MemoryChunk* chunk) { Iterate(chunk, callback); }); |
| } |
| |
| // Iterates over all memory chunks that contains non-empty slot sets. |
| // The callback should take (MemoryChunk* chunk) and return void. |
| template <typename Callback> |
| static void IterateMemoryChunks(Heap* heap, Callback callback) { |
| MemoryChunkIterator it(heap, direction == OLD_TO_OLD |
| ? MemoryChunkIterator::ALL |
| : MemoryChunkIterator::ALL_BUT_CODE_SPACE); |
| MemoryChunk* chunk; |
| while ((chunk = it.next()) != nullptr) { |
| SlotSet* slots = GetSlotSet(chunk); |
| TypedSlotSet* typed_slots = GetTypedSlotSet(chunk); |
| if (slots != nullptr || typed_slots != nullptr) { |
| callback(chunk); |
| } |
| } |
| } |
| |
| // Iterates and filters the remembered set in the given memory chunk with |
| // the given callback. The callback should take (Address slot) and return |
| // SlotCallbackResult. |
| template <typename Callback> |
| static void Iterate(MemoryChunk* chunk, Callback callback) { |
| SlotSet* slots = GetSlotSet(chunk); |
| if (slots != nullptr) { |
| size_t pages = (chunk->size() + Page::kPageSize - 1) / Page::kPageSize; |
| int new_count = 0; |
| for (size_t page = 0; page < pages; page++) { |
| new_count += slots[page].Iterate(callback); |
| } |
| if (new_count == 0) { |
| ReleaseSlotSet(chunk); |
| } |
| } |
| } |
| |
| // Iterates and filters the remembered set with the given callback. |
| // The callback should take (HeapObject** slot, HeapObject* target) and |
| // update the slot. |
| // A special wrapper takes care of filtering the slots based on their values. |
| // For OLD_TO_NEW case: slots that do not point to the ToSpace after |
| // callback invocation will be removed from the set. |
| template <typename Callback> |
| static void IterateWithWrapper(Heap* heap, Callback callback) { |
| Iterate(heap, [heap, callback](Address addr) { |
| return Wrapper(heap, addr, callback); |
| }); |
| } |
| |
| template <typename Callback> |
| static void IterateWithWrapper(Heap* heap, MemoryChunk* chunk, |
| Callback callback) { |
| Iterate(chunk, [heap, callback](Address addr) { |
| return Wrapper(heap, addr, callback); |
| }); |
| } |
| |
| // Given a page and a typed slot in that page, this function adds the slot |
| // to the remembered set. |
| static void InsertTyped(Page* page, SlotType slot_type, Address slot_addr) { |
| STATIC_ASSERT(direction == OLD_TO_OLD); |
| TypedSlotSet* slot_set = page->typed_old_to_old_slots(); |
| if (slot_set == nullptr) { |
| page->AllocateTypedOldToOldSlots(); |
| slot_set = page->typed_old_to_old_slots(); |
| } |
| uintptr_t offset = slot_addr - page->address(); |
| DCHECK_LT(offset, static_cast<uintptr_t>(TypedSlotSet::kMaxOffset)); |
| slot_set->Insert(slot_type, static_cast<uint32_t>(offset)); |
| } |
| |
| // Given a page and a range of typed slots in that page, this function removes |
| // the slots from the remembered set. |
| static void RemoveRangeTyped(Page* page, Address start, Address end) { |
| TypedSlotSet* slots = page->typed_old_to_old_slots(); |
| if (slots != nullptr) { |
| slots->Iterate([start, end](SlotType slot_type, Address slot_addr) { |
| return start <= slot_addr && slot_addr < end ? REMOVE_SLOT : KEEP_SLOT; |
| }); |
| } |
| } |
| |
| // Iterates and filters typed old to old pointers in the given memory chunk |
| // with the given callback. The callback should take (SlotType slot_type, |
| // Address slot_addr) and return SlotCallbackResult. |
| template <typename Callback> |
| static void IterateTyped(MemoryChunk* chunk, Callback callback) { |
| TypedSlotSet* slots = chunk->typed_old_to_old_slots(); |
| if (slots != nullptr) { |
| int new_count = slots->Iterate(callback); |
| if (new_count == 0) { |
| chunk->ReleaseTypedOldToOldSlots(); |
| } |
| } |
| } |
| |
| // Clear all old to old slots from the remembered set. |
| static void ClearAll(Heap* heap) { |
| STATIC_ASSERT(direction == OLD_TO_OLD); |
| MemoryChunkIterator it(heap, MemoryChunkIterator::ALL); |
| MemoryChunk* chunk; |
| while ((chunk = it.next()) != nullptr) { |
| chunk->ReleaseOldToOldSlots(); |
| chunk->ReleaseTypedOldToOldSlots(); |
| } |
| } |
| |
| // Eliminates all stale slots from the remembered set, i.e. |
| // slots that are not part of live objects anymore. This method must be |
| // called after marking, when the whole transitive closure is known and |
| // must be called before sweeping when mark bits are still intact. |
| static void ClearInvalidSlots(Heap* heap); |
| |
| static void VerifyValidSlots(Heap* heap); |
| |
| private: |
| static SlotSet* GetSlotSet(MemoryChunk* chunk) { |
| if (direction == OLD_TO_OLD) { |
| return chunk->old_to_old_slots(); |
| } else { |
| return chunk->old_to_new_slots(); |
| } |
| } |
| |
| static TypedSlotSet* GetTypedSlotSet(MemoryChunk* chunk) { |
| if (direction == OLD_TO_OLD) { |
| return chunk->typed_old_to_old_slots(); |
| } else { |
| return nullptr; |
| } |
| } |
| |
| static void ReleaseSlotSet(MemoryChunk* chunk) { |
| if (direction == OLD_TO_OLD) { |
| chunk->ReleaseOldToOldSlots(); |
| } else { |
| chunk->ReleaseOldToNewSlots(); |
| } |
| } |
| |
| static SlotSet* AllocateSlotSet(MemoryChunk* chunk) { |
| if (direction == OLD_TO_OLD) { |
| chunk->AllocateOldToOldSlots(); |
| return chunk->old_to_old_slots(); |
| } else { |
| chunk->AllocateOldToNewSlots(); |
| return chunk->old_to_new_slots(); |
| } |
| } |
| |
| template <typename Callback> |
| static SlotCallbackResult Wrapper(Heap* heap, Address slot_address, |
| Callback slot_callback) { |
| STATIC_ASSERT(direction == OLD_TO_NEW); |
| Object** slot = reinterpret_cast<Object**>(slot_address); |
| Object* object = *slot; |
| if (heap->InFromSpace(object)) { |
| HeapObject* heap_object = reinterpret_cast<HeapObject*>(object); |
| DCHECK(heap_object->IsHeapObject()); |
| slot_callback(reinterpret_cast<HeapObject**>(slot), heap_object); |
| object = *slot; |
| // If the object was in from space before and is after executing the |
| // callback in to space, the object is still live. |
| // Unfortunately, we do not know about the slot. It could be in a |
| // just freed free space object. |
| if (heap->InToSpace(object)) { |
| return KEEP_SLOT; |
| } |
| } else { |
| DCHECK(!heap->InNewSpace(object)); |
| } |
| return REMOVE_SLOT; |
| } |
| |
| static bool IsValidSlot(Heap* heap, MemoryChunk* chunk, Object** slot); |
| }; |
| |
| } // namespace internal |
| } // namespace v8 |
| |
| #endif // V8_REMEMBERED_SET_H |