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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.
#ifndef V8_HEAP_REMEMBERED_SET_H_
#define V8_HEAP_REMEMBERED_SET_H_
#include <memory>
#include "src/base/bounds.h"
#include "src/base/memory.h"
#include "src/codegen/reloc-info.h"
#include "src/common/globals.h"
#include "src/heap/base/worklist.h"
#include "src/heap/heap.h"
#include "src/heap/memory-chunk-layout.h"
#include "src/heap/memory-chunk.h"
#include "src/heap/paged-spaces.h"
#include "src/heap/slot-set.h"
#include "src/heap/spaces.h"
namespace v8 {
namespace internal {
class RememberedSetOperations {
public:
// Given a page and a slot in that page, this function adds the slot to the
// remembered set.
template <AccessMode access_mode>
static void Insert(SlotSet* slot_set, MemoryChunk* chunk, Address slot_addr) {
DCHECK(chunk->Contains(slot_addr));
uintptr_t offset = slot_addr - chunk->address();
slot_set->Insert<access_mode == v8::internal::AccessMode::ATOMIC
? v8::internal::SlotSet::AccessMode::ATOMIC
: v8::internal::SlotSet::AccessMode::NON_ATOMIC>(
offset);
}
template <AccessMode access_mode = AccessMode::ATOMIC, typename Callback>
static int Iterate(SlotSet* slot_set, const MemoryChunk* chunk,
Callback callback, SlotSet::EmptyBucketMode mode) {
int slots = 0;
if (slot_set != nullptr) {
slots += slot_set->Iterate<access_mode>(chunk->address(), 0,
chunk->buckets(), callback, mode);
}
return slots;
}
static void Remove(SlotSet* slot_set, MemoryChunk* chunk, Address slot_addr) {
if (slot_set != nullptr) {
uintptr_t offset = slot_addr - chunk->address();
slot_set->Remove(offset);
}
}
static void RemoveRange(SlotSet* slot_set, MemoryChunk* chunk, Address start,
Address end, SlotSet::EmptyBucketMode mode) {
if (slot_set != nullptr) {
uintptr_t start_offset = start - chunk->address();
uintptr_t end_offset = end - chunk->address();
DCHECK_LT(start_offset, end_offset);
slot_set->RemoveRange(static_cast<int>(start_offset),
static_cast<int>(end_offset), chunk->buckets(),
mode);
}
}
static void CheckNoneInRange(SlotSet* slot_set, MemoryChunk* chunk,
Address start, Address end) {
if (slot_set != nullptr) {
size_t start_bucket = SlotSet::BucketForSlot(start - chunk->address());
// Both 'end' and 'end_bucket' are exclusive limits, so do some index
// juggling to make sure we get the right bucket even if the end address
// is at the start of a bucket.
size_t end_bucket =
SlotSet::BucketForSlot(end - chunk->address() - kTaggedSize) + 1;
slot_set->Iterate(
chunk->address(), start_bucket, end_bucket,
[start, end](MaybeObjectSlot slot) {
CHECK(slot.address() < start || slot.address() >= end);
return KEEP_SLOT;
},
SlotSet::KEEP_EMPTY_BUCKETS);
}
}
};
template <RememberedSetType type>
class RememberedSet : public AllStatic {
public:
// Given a page and a slot in that page, this function adds the slot to the
// remembered set.
template <AccessMode access_mode>
static void Insert(MemoryChunk* chunk, Address slot_addr) {
DCHECK(chunk->Contains(slot_addr));
SlotSet* slot_set = chunk->slot_set<type, access_mode>();
if (slot_set == nullptr) {
slot_set = chunk->AllocateSlotSet(type);
}
RememberedSetOperations::Insert<access_mode>(slot_set, chunk, slot_addr);
}
// Given a page and a slot set, this function merges the slot set to the set
// of the page. |other_slot_set| should not be used after calling this method.
static void MergeAndDelete(MemoryChunk* chunk, SlotSet&& other_slot_set) {
static_assert(type == RememberedSetType::OLD_TO_NEW ||
type == RememberedSetType::OLD_TO_NEW_BACKGROUND);
SlotSet* slot_set = chunk->slot_set<type, AccessMode::NON_ATOMIC>();
if (slot_set == nullptr) {
chunk->set_slot_set<type, AccessMode::NON_ATOMIC>(&other_slot_set);
return;
}
slot_set->Merge(&other_slot_set, chunk->buckets());
SlotSet::Delete(&other_slot_set, chunk->buckets());
}
// Given a page and a slot set, this function merges the slot set to the set
// of the page. |other_slot_set| should not be used after calling this method.
static void MergeAndDeleteTyped(MemoryChunk* chunk,
TypedSlotSet&& other_typed_slot_set) {
static_assert(type == RememberedSetType::OLD_TO_NEW);
TypedSlotSet* typed_slot_set =
chunk->typed_slot_set<type, AccessMode::NON_ATOMIC>();
if (typed_slot_set == nullptr) {
chunk->set_typed_slot_set<RememberedSetType::OLD_TO_NEW,
AccessMode::NON_ATOMIC>(&other_typed_slot_set);
return;
}
typed_slot_set->Merge(&other_typed_slot_set);
delete &other_typed_slot_set;
}
// Given a page and a slot in that page, this function returns true if
// the remembered set contains the slot.
static bool Contains(MemoryChunk* chunk, Address slot_addr) {
DCHECK(chunk->Contains(slot_addr));
SlotSet* slot_set = chunk->slot_set<type>();
if (slot_set == nullptr) {
return false;
}
uintptr_t offset = slot_addr - chunk->address();
return slot_set->Contains(offset);
}
static void CheckNoneInRange(MemoryChunk* chunk, Address start, Address end) {
SlotSet* slot_set = chunk->slot_set<type>();
RememberedSetOperations::CheckNoneInRange(slot_set, chunk, start, end);
}
// 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(MemoryChunk* chunk, Address slot_addr) {
DCHECK(chunk->Contains(slot_addr));
SlotSet* slot_set = chunk->slot_set<type>();
RememberedSetOperations::Remove(slot_set, chunk, slot_addr);
}
// Given a page and a range of slots in that page, this function removes the
// slots from the remembered set.
static void RemoveRange(MemoryChunk* chunk, Address start, Address end,
SlotSet::EmptyBucketMode mode) {
SlotSet* slot_set = chunk->slot_set<type>();
RememberedSetOperations::RemoveRange(slot_set, chunk, start, end, mode);
}
// 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) {
OldGenerationMemoryChunkIterator it(heap);
MemoryChunk* chunk;
while ((chunk = it.next()) != nullptr) {
SlotSet* slot_set = chunk->slot_set<type>();
TypedSlotSet* typed_slot_set = chunk->typed_slot_set<type>();
if (slot_set != nullptr || typed_slot_set != 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.
//
// Notice that |mode| can only be of FREE* or PREFREE* if there are no other
// threads concurrently inserting slots.
template <AccessMode access_mode = AccessMode::ATOMIC, typename Callback>
static int Iterate(MemoryChunk* chunk, Callback callback,
SlotSet::EmptyBucketMode mode) {
SlotSet* slot_set = chunk->slot_set<type>();
return Iterate<access_mode>(slot_set, chunk, callback, mode);
}
template <AccessMode access_mode = AccessMode::ATOMIC, typename Callback>
static int Iterate(SlotSet* slot_set, const MemoryChunk* chunk,
Callback callback, SlotSet::EmptyBucketMode mode) {
return RememberedSetOperations::Iterate<access_mode>(slot_set, chunk,
callback, mode);
}
template <typename Callback>
static int IterateAndTrackEmptyBuckets(
MemoryChunk* chunk, Callback callback,
::heap::base::Worklist<MemoryChunk*, 64>::Local* empty_chunks) {
SlotSet* slot_set = chunk->slot_set<type>();
int slots = 0;
if (slot_set != nullptr) {
PossiblyEmptyBuckets* possibly_empty_buckets =
chunk->possibly_empty_buckets();
slots += slot_set->IterateAndTrackEmptyBuckets(chunk->address(), 0,
chunk->buckets(), callback,
possibly_empty_buckets);
if (!possibly_empty_buckets->IsEmpty()) empty_chunks->Push(chunk);
}
return slots;
}
static bool CheckPossiblyEmptyBuckets(MemoryChunk* chunk) {
DCHECK(type == OLD_TO_NEW || type == OLD_TO_NEW_BACKGROUND);
SlotSet* slot_set = chunk->slot_set<type, AccessMode::NON_ATOMIC>();
if (slot_set != nullptr &&
slot_set->CheckPossiblyEmptyBuckets(chunk->buckets(),
chunk->possibly_empty_buckets())) {
chunk->ReleaseSlotSet(type);
return true;
}
return false;
}
// Given a page and a typed slot in that page, this function adds the slot
// to the remembered set.
static void InsertTyped(MemoryChunk* memory_chunk, SlotType slot_type,
uint32_t offset) {
TypedSlotSet* slot_set = memory_chunk->typed_slot_set<type>();
if (slot_set == nullptr) {
slot_set = memory_chunk->AllocateTypedSlotSet(type);
}
slot_set->Insert(slot_type, offset);
}
static void MergeTyped(MemoryChunk* page, std::unique_ptr<TypedSlots> other) {
TypedSlotSet* slot_set = page->typed_slot_set<type>();
if (slot_set == nullptr) {
CodePageHeaderModificationScope header_modification_scope(
"Allocating a typed slot set requires header write permissions.");
slot_set = page->AllocateTypedSlotSet(type);
}
slot_set->Merge(other.get());
}
// Given a page and a range of typed slots in that page, this function removes
// the slots from the remembered set.
static void RemoveRangeTyped(MemoryChunk* page, Address start, Address end) {
TypedSlotSet* slot_set = page->typed_slot_set<type>();
if (slot_set != nullptr) {
slot_set->Iterate(
[=](SlotType slot_type, Address slot_addr) {
return start <= slot_addr && slot_addr < end ? REMOVE_SLOT
: KEEP_SLOT;
},
TypedSlotSet::FREE_EMPTY_CHUNKS);
}
}
// Iterates and filters typed pointers in the given memory chunk with the
// given callback. The callback should take (SlotType slot_type, Address addr)
// and return SlotCallbackResult.
template <typename Callback>
static int IterateTyped(MemoryChunk* chunk, Callback callback) {
TypedSlotSet* slot_set = chunk->typed_slot_set<type>();
if (!slot_set) return 0;
return IterateTyped(slot_set, callback);
}
template <typename Callback>
static int IterateTyped(TypedSlotSet* slot_set, Callback callback) {
DCHECK_NOT_NULL(slot_set);
return slot_set->Iterate(callback, TypedSlotSet::KEEP_EMPTY_CHUNKS);
}
// Clear all old to old slots from the remembered set.
static void ClearAll(Heap* heap) {
static_assert(type == OLD_TO_OLD || type == OLD_TO_CODE);
OldGenerationMemoryChunkIterator it(heap);
MemoryChunk* chunk;
while ((chunk = it.next()) != nullptr) {
chunk->ReleaseSlotSet(OLD_TO_OLD);
chunk->ReleaseSlotSet(OLD_TO_CODE);
chunk->ReleaseTypedSlotSet(OLD_TO_OLD);
}
}
};
class UpdateTypedSlotHelper {
public:
// Updates a typed slot using an untyped slot callback where |addr| depending
// on slot type represents either address for respective RelocInfo or address
// of the uncompressed constant pool entry.
// The callback accepts FullMaybeObjectSlot and returns SlotCallbackResult.
template <typename Callback>
static SlotCallbackResult UpdateTypedSlot(Heap* heap, SlotType slot_type,
Address addr, Callback callback);
// Returns the HeapObject referenced by the given typed slot entry.
inline static Tagged<HeapObject> GetTargetObject(Heap* heap,
SlotType slot_type,
Address addr);
private:
// Updates a code entry slot using an untyped slot callback.
// The callback accepts FullMaybeObjectSlot and returns SlotCallbackResult.
template <typename Callback>
static SlotCallbackResult UpdateCodeEntry(Address entry_address,
Callback callback) {
Tagged<InstructionStream> code =
InstructionStream::FromEntryAddress(entry_address);
Tagged<InstructionStream> old_code = code;
SlotCallbackResult result = callback(FullMaybeObjectSlot(&code));
DCHECK(!HasWeakHeapObjectTag(code));
if (code != old_code) {
base::Memory<Address>(entry_address) = code->instruction_start();
}
return result;
}
// Updates a code target slot using an untyped slot callback.
// The callback accepts FullMaybeObjectSlot and returns SlotCallbackResult.
template <typename Callback>
static SlotCallbackResult UpdateCodeTarget(WritableRelocInfo* rinfo,
Callback callback) {
DCHECK(RelocInfo::IsCodeTargetMode(rinfo->rmode()));
Tagged<InstructionStream> old_target =
InstructionStream::FromTargetAddress(rinfo->target_address());
Tagged<InstructionStream> new_target = old_target;
SlotCallbackResult result = callback(FullMaybeObjectSlot(&new_target));
DCHECK(!HasWeakHeapObjectTag(new_target));
if (new_target != old_target) {
rinfo->set_target_address(
InstructionStream::cast(new_target)->instruction_start());
}
return result;
}
// Updates an embedded pointer slot using an untyped slot callback.
// The callback accepts FullMaybeObjectSlot and returns SlotCallbackResult.
template <typename Callback>
static SlotCallbackResult UpdateEmbeddedPointer(Heap* heap,
WritableRelocInfo* rinfo,
Callback callback) {
DCHECK(RelocInfo::IsEmbeddedObjectMode(rinfo->rmode()));
Tagged<HeapObject> old_target = rinfo->target_object(heap->isolate());
Tagged<HeapObject> new_target = old_target;
SlotCallbackResult result = callback(FullMaybeObjectSlot(&new_target));
DCHECK(!HasWeakHeapObjectTag(new_target));
if (new_target != old_target) {
rinfo->set_target_object(HeapObject::cast(new_target));
}
return result;
}
};
} // namespace internal
} // namespace v8
#endif // V8_HEAP_REMEMBERED_SET_H_
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