src/heap/remembered-set.h - platform/external/v8 - Git at Google

 // 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
	// 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