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// 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.
#include "src/heap/remembered-set.h"
#include "src/heap/heap-inl.h"
#include "src/heap/heap.h"
#include "src/heap/mark-compact.h"
#include "src/heap/slot-set.h"
#include "src/heap/spaces.h"
#include "src/heap/store-buffer.h"
#include "src/macro-assembler.h"
namespace v8 {
namespace internal {
template <PointerDirection direction>
void RememberedSet<direction>::ClearInvalidSlots(Heap* heap) {
STATIC_ASSERT(direction == OLD_TO_NEW);
for (MemoryChunk* chunk : *heap->old_space()) {
SlotSet* slots = GetSlotSet(chunk);
if (slots != nullptr) {
slots->Iterate(
[heap, chunk](Address addr) {
Object** slot = reinterpret_cast<Object**>(addr);
return IsValidSlot(heap, chunk, slot) ? KEEP_SLOT : REMOVE_SLOT;
},
SlotSet::PREFREE_EMPTY_BUCKETS);
}
}
for (MemoryChunk* chunk : *heap->code_space()) {
TypedSlotSet* slots = GetTypedSlotSet(chunk);
if (slots != nullptr) {
slots->Iterate(
[heap, chunk](SlotType type, Address host_addr, Address addr) {
if (Marking::IsBlack(ObjectMarking::MarkBitFrom(host_addr))) {
return KEEP_SLOT;
} else {
return REMOVE_SLOT;
}
},
TypedSlotSet::PREFREE_EMPTY_CHUNKS);
}
}
for (MemoryChunk* chunk : *heap->map_space()) {
SlotSet* slots = GetSlotSet(chunk);
if (slots != nullptr) {
slots->Iterate(
[heap, chunk](Address addr) {
Object** slot = reinterpret_cast<Object**>(addr);
// TODO(mlippautz): In map space all allocations would ideally be
// map
// aligned. After establishing this invariant IsValidSlot could just
// refer to the containing object using alignment and check the mark
// bits.
return IsValidSlot(heap, chunk, slot) ? KEEP_SLOT : REMOVE_SLOT;
},
SlotSet::PREFREE_EMPTY_BUCKETS);
}
}
}
template <PointerDirection direction>
void RememberedSet<direction>::VerifyValidSlots(Heap* heap) {
Iterate(heap, [heap](Address addr) {
HeapObject* obj =
heap->mark_compact_collector()->FindBlackObjectBySlotSlow(addr);
if (obj == nullptr) {
// The slot is in dead object.
MemoryChunk* chunk = MemoryChunk::FromAnyPointerAddress(heap, addr);
AllocationSpace owner = chunk->owner()->identity();
// The old to old remembered set should not have dead slots.
CHECK_NE(direction, OLD_TO_OLD);
// The old to new remembered set is allowed to have slots in dead
// objects only in map and large object space because these space
// cannot have raw untagged pointers.
CHECK(owner == MAP_SPACE || owner == LO_SPACE);
} else {
int offset = static_cast<int>(addr - obj->address());
CHECK(obj->IsValidSlot(offset));
}
return KEEP_SLOT;
});
}
template <PointerDirection direction>
bool RememberedSet<direction>::IsValidSlot(Heap* heap, MemoryChunk* chunk,
Object** slot) {
STATIC_ASSERT(direction == OLD_TO_NEW);
Object* object = *slot;
if (!heap->InNewSpace(object)) {
return false;
}
HeapObject* heap_object = HeapObject::cast(object);
// If the target object is not black, the source slot must be part
// of a non-black (dead) object.
return Marking::IsBlack(ObjectMarking::MarkBitFrom(heap_object)) &&
heap->mark_compact_collector()->IsSlotInBlackObject(
chunk, reinterpret_cast<Address>(slot));
}
template void RememberedSet<OLD_TO_NEW>::ClearInvalidSlots(Heap* heap);
template void RememberedSet<OLD_TO_NEW>::VerifyValidSlots(Heap* heap);
template void RememberedSet<OLD_TO_OLD>::VerifyValidSlots(Heap* heap);
} // namespace internal
} // namespace v8
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