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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sw=2 et tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at */
#ifndef gc_Nursery_h
#define gc_Nursery_h
#include "mozilla/ArrayUtils.h"
#include "mozilla/EnumeratedArray.h"
#include "mozilla/Maybe.h"
#include "mozilla/TimeStamp.h"
#include "gc/GCParallelTask.h"
#include "gc/Heap.h"
#include "js/AllocPolicy.h"
#include "js/Class.h"
#include "js/HeapAPI.h"
#include "js/TracingAPI.h"
#include "js/TypeDecls.h"
#include "js/Vector.h"
#include "util/Text.h"
/* Key Header text */ \
_(Total, "total") \
_(TraceValues, "mkVals") \
_(TraceCells, "mkClls") \
_(TraceSlots, "mkSlts") \
_(TraceWholeCells, "mcWCll") \
_(TraceGenericEntries, "mkGnrc") \
_(CheckHashTables, "ckTbls") \
_(MarkRuntime, "mkRntm") \
_(MarkDebugger, "mkDbgr") \
_(SweepCaches, "swpCch") \
_(CollectToFP, "collct") \
_(ObjectsTenuredCallback, "tenCB") \
_(Sweep, "sweep") \
_(UpdateJitActivations, "updtIn") \
_(FreeMallocedBuffers, "frSlts") \
_(ClearStoreBuffer, "clrSB") \
_(ClearNursery, "clear") \
_(PurgeStringToAtomCache, "pStoA") \
_(Pretenure, "pretnr")
template <typename T>
class SharedMem;
class JSDependentString;
namespace js {
struct StringStats;
class AutoLockGCBgAlloc;
class ObjectElements;
class PlainObject;
class NativeObject;
class Nursery;
struct NurseryChunk;
class HeapSlot;
class JSONPrinter;
class MapObject;
class SetObject;
namespace gc {
class AutoMaybeStartBackgroundAllocation;
class AutoTraceSession;
struct Cell;
class GCSchedulingTunables;
class MinorCollectionTracer;
class RelocationOverlay;
class StringRelocationOverlay;
enum class AllocKind : uint8_t;
class TenuredCell;
} // namespace gc
namespace jit {
class MacroAssembler;
} // namespace jit
class NurseryDecommitTask : public GCParallelTask {
explicit NurseryDecommitTask(gc::GCRuntime* gc);
bool reserveSpaceForBytes(size_t nbytes);
bool isEmpty(const AutoLockHelperThreadState& lock) const;
void queueChunk(NurseryChunk* chunk, const AutoLockHelperThreadState& lock);
void queueRange(size_t newCapacity, NurseryChunk& chunk,
const AutoLockHelperThreadState& lock);
using NurseryChunkVector = Vector<NurseryChunk*, 0, SystemAllocPolicy>;
void run(AutoLockHelperThreadState& lock) override;
NurseryChunkVector& chunksToDecommit() { return chunksToDecommit_.ref(); }
const NurseryChunkVector& chunksToDecommit() const {
return chunksToDecommit_.ref();
MainThreadOrGCTaskData<NurseryChunkVector> chunksToDecommit_;
MainThreadOrGCTaskData<NurseryChunk*> partialChunk;
MainThreadOrGCTaskData<size_t> partialCapacity;
class TenuringTracer final : public GenericTracer {
friend class Nursery;
Nursery& nursery_;
// Amount of data moved to the tenured generation during collection.
size_t tenuredSize;
// Number of cells moved to the tenured generation.
size_t tenuredCells;
// These lists are threaded through the Nursery using the space from
// already moved things. The lists are used to fix up the moved things and
// to find things held live by intra-Nursery pointers.
gc::RelocationOverlay* objHead;
gc::RelocationOverlay** objTail;
gc::StringRelocationOverlay* stringHead;
gc::StringRelocationOverlay** stringTail;
gc::RelocationOverlay* bigIntHead;
gc::RelocationOverlay** bigIntTail;
TenuringTracer(JSRuntime* rt, Nursery* nursery);
JSObject* onObjectEdge(JSObject* obj) override;
JSString* onStringEdge(JSString* str) override;
JS::Symbol* onSymbolEdge(JS::Symbol* sym) override;
JS::BigInt* onBigIntEdge(JS::BigInt* bi) override;
js::BaseScript* onScriptEdge(BaseScript* script) override;
js::Shape* onShapeEdge(Shape* shape) override;
js::RegExpShared* onRegExpSharedEdge(RegExpShared* shared) override;
js::ObjectGroup* onObjectGroupEdge(ObjectGroup* group) override;
js::BaseShape* onBaseShapeEdge(BaseShape* base) override;
js::jit::JitCode* onJitCodeEdge(jit::JitCode* code) override;
js::Scope* onScopeEdge(Scope* scope) override;
Nursery& nursery() { return nursery_; }
template <typename T>
void traverse(T** thingp);
void traverse(JS::Value* thingp);
// The store buffers need to be able to call these directly.
void traceObject(JSObject* src);
void traceObjectSlots(NativeObject* nobj, uint32_t start, uint32_t end);
void traceSlots(JS::Value* vp, uint32_t nslots);
void traceString(JSString* src);
void traceBigInt(JS::BigInt* src);
inline void insertIntoObjectFixupList(gc::RelocationOverlay* entry);
inline void insertIntoStringFixupList(gc::StringRelocationOverlay* entry);
inline void insertIntoBigIntFixupList(gc::RelocationOverlay* entry);
template <typename T>
inline T* allocTenured(JS::Zone* zone, gc::AllocKind kind);
JSString* allocTenuredString(JSString* src, JS::Zone* zone,
gc::AllocKind dstKind);
inline JSObject* movePlainObjectToTenured(PlainObject* src);
JSObject* moveToTenuredSlow(JSObject* src);
JSString* moveToTenured(JSString* src);
JS::BigInt* moveToTenured(JS::BigInt* src);
size_t moveElementsToTenured(NativeObject* dst, NativeObject* src,
gc::AllocKind dstKind);
size_t moveSlotsToTenured(NativeObject* dst, NativeObject* src);
size_t moveStringToTenured(JSString* dst, JSString* src,
gc::AllocKind dstKind);
size_t moveBigIntToTenured(JS::BigInt* dst, JS::BigInt* src,
gc::AllocKind dstKind);
void traceSlots(JS::Value* vp, JS::Value* end);
// Classes with JSCLASS_SKIP_NURSERY_FINALIZE or Wrapper classes with
// CROSS_COMPARTMENT flags will not have their finalizer called if they are
// nursery allocated and not promoted to the tenured heap. The finalizers for
// these classes must do nothing except free data which was allocated via
// Nursery::allocateBuffer.
inline bool CanNurseryAllocateFinalizedClass(const JSClass* const clasp) {
return clasp->flags & JSCLASS_SKIP_NURSERY_FINALIZE;
class Nursery {
static const size_t Alignment = gc::ChunkSize;
static const size_t ChunkShift = gc::ChunkShift;
// SubChunkStep is the minimum amount to adjust the nursery's size by.
static const size_t SubChunkStep = gc::ArenaSize;
using BufferRelocationOverlay = void*;
using BufferSet = HashSet<void*, PointerHasher<void*>, SystemAllocPolicy>;
explicit Nursery(gc::GCRuntime* gc);
MOZ_MUST_USE bool init(AutoLockGCBgAlloc& lock);
// Number of allocated (ready to use) chunks.
unsigned allocatedChunkCount() const { return chunks_.length(); }
// Total number of chunks and the capacity of the nursery. Chunks will be
// lazilly allocated and added to the chunks array up to this limit, after
// that the nursery must be collected, this limit may be raised during
// collection.
unsigned maxChunkCount() const {
return HowMany(capacity(), gc::ChunkSize);
void enable();
void disable();
bool isEnabled() const { return capacity() != 0; }
void enableStrings();
void disableStrings();
bool canAllocateStrings() const { return canAllocateStrings_; }
void enableBigInts();
void disableBigInts();
bool canAllocateBigInts() const { return canAllocateBigInts_; }
// Return true if no allocations have been made since the last collection.
bool isEmpty() const;
// Check whether an arbitrary pointer is within the nursery. This is
// slower than IsInsideNursery(Cell*), but works on all types of pointers.
MOZ_ALWAYS_INLINE bool isInside(gc::Cell* cellp) const = delete;
MOZ_ALWAYS_INLINE bool isInside(const void* p) const {
for (auto chunk : chunks_) {
if (uintptr_t(p) - uintptr_t(chunk) < gc::ChunkSize) {
return true;
return false;
template <typename T>
inline bool isInside(const SharedMem<T>& p) const;
// Allocate and return a pointer to a new GC object with its |slots|
// pointer pre-filled. Returns nullptr if the Nursery is full.
JSObject* allocateObject(JSContext* cx, size_t size, size_t numDynamic,
const JSClass* clasp);
// Allocate and return a pointer to a new GC thing. Returns nullptr if the
// Nursery is full.
gc::Cell* allocateCell(JS::Zone* zone, size_t size, JS::TraceKind kind);
gc::Cell* allocateBigInt(JS::Zone* zone, size_t size) {
return allocateCell(zone, size, JS::TraceKind::BigInt);
gc::Cell* allocateString(JS::Zone* zone, size_t size);
static size_t nurseryCellHeaderSize() {
return sizeof(gc::NurseryCellHeader);
// Allocate a buffer for a given zone, using the nursery if possible.
void* allocateBuffer(JS::Zone* zone, size_t nbytes);
// Allocate a buffer for a given object, using the nursery if possible and
// obj is in the nursery.
void* allocateBuffer(JSObject* obj, size_t nbytes);
// Allocate a buffer for a given object, always using the nursery if obj is
// in the nursery. The requested size must be less than or equal to
// MaxNurseryBufferSize.
void* allocateBufferSameLocation(JSObject* obj, size_t nbytes);
// Allocate a zero-initialized buffer for a given zone, using the nursery if
// possible. If the buffer isn't allocated in the nursery, the given arena is
// used.
void* allocateZeroedBuffer(JS::Zone* zone, size_t nbytes,
arena_id_t arena = js::MallocArena);
// Allocate a zero-initialized buffer for a given object, using the nursery if
// possible and obj is in the nursery. If the buffer isn't allocated in the
// nursery, the given arena is used.
void* allocateZeroedBuffer(JSObject* obj, size_t nbytes,
arena_id_t arena = js::MallocArena);
// Resize an existing buffer.
void* reallocateBuffer(JS::Zone* zone, gc::Cell* cell, void* oldBuffer,
size_t oldBytes, size_t newBytes);
// Allocate a digits buffer for a given BigInt, using the nursery if possible
// and |bi| is in the nursery.
void* allocateBuffer(JS::BigInt* bi, size_t nbytes);
// Free an object buffer.
void freeBuffer(void* buffer, size_t nbytes);
// The maximum number of bytes allowed to reside in nursery buffers.
static const size_t MaxNurseryBufferSize = 1024;
// Do a minor collection.
void collect(JSGCInvocationKind kind, JS::GCReason reason);
// If the thing at |*ref| in the Nursery has been forwarded, set |*ref| to
// the new location and return true. Otherwise return false and leave
// |*ref| unset.
MOZ_ALWAYS_INLINE MOZ_MUST_USE static bool getForwardedPointer(
js::gc::Cell** ref);
// Forward a slots/elements pointer stored in an Ion frame.
void forwardBufferPointer(uintptr_t* pSlotsElems);
inline void maybeSetForwardingPointer(JSTracer* trc, void* oldData,
void* newData, bool direct);
inline void setForwardingPointerWhileTenuring(void* oldData, void* newData,
bool direct);
// Register a malloced buffer that is held by a nursery object, which
// should be freed at the end of a minor GC. Buffers are unregistered when
// their owning objects are tenured.
MOZ_MUST_USE bool registerMallocedBuffer(void* buffer, size_t nbytes);
// Mark a malloced buffer as no longer needing to be freed.
void removeMallocedBuffer(void* buffer, size_t nbytes) {
MOZ_ASSERT(nbytes > 0);
MOZ_ASSERT(mallocedBufferBytes >= nbytes);
mallocedBufferBytes -= nbytes;
// Mark a malloced buffer as no longer needing to be freed during minor
// GC. There's no need to account for the size here since all remaining
// buffers will soon be freed.
void removeMallocedBufferDuringMinorGC(void* buffer) {
MOZ_MUST_USE bool addedUniqueIdToCell(gc::Cell* cell) {
return cellsWithUid_.append(cell);
MOZ_MUST_USE bool queueDictionaryModeObjectToSweep(NativeObject* obj);
size_t sizeOfMallocedBuffers(mozilla::MallocSizeOf mallocSizeOf) const {
size_t total = 0;
for (BufferSet::Range r = mallocedBuffers.all(); !r.empty(); r.popFront()) {
total += mallocSizeOf(r.front());
total += mallocedBuffers.shallowSizeOfExcludingThis(mallocSizeOf);
return total;
// The number of bytes from the start position to the end of the nursery.
// pass maxChunkCount(), allocatedChunkCount() or chunkCountLimit()
// to calculate the nursery size, current lazy-allocated size or nursery
// limit respectively.
size_t spaceToEnd(unsigned chunkCount) const;
size_t capacity() const { return capacity_; }
size_t committed() const { return spaceToEnd(allocatedChunkCount()); }
// Used and free space both include chunk headers for that part of the
// nursery.
// usedSpace() + freeSpace() == capacity()
MOZ_ALWAYS_INLINE size_t usedSpace() const {
return capacity() - freeSpace();
MOZ_ALWAYS_INLINE size_t freeSpace() const {
MOZ_ASSERT(currentEnd_ - position_ <= NurseryChunkUsableSize);
MOZ_ASSERT(currentChunk_ < maxChunkCount());
return (currentEnd_ - position_) +
(maxChunkCount() - currentChunk_ - 1) * gc::ChunkSize;
#ifdef JS_GC_ZEAL
void enterZealMode();
void leaveZealMode();
// Write profile time JSON on JSONPrinter.
void renderProfileJSON(JSONPrinter& json) const;
// Print header line for profile times.
static void printProfileHeader();
// Print total profile times on shutdown.
void printTotalProfileTimes();
void* addressOfPosition() const { return (void**)&position_; }
const void* addressOfCurrentEnd() const { return (void**)&currentEnd_; }
const void* addressOfCurrentStringEnd() const {
return (void*)&currentStringEnd_;
const void* addressOfCurrentBigIntEnd() const {
return (void*)&currentBigIntEnd_;
void requestMinorGC(JS::GCReason reason) const;
bool minorGCRequested() const {
return minorGCTriggerReason_ != JS::GCReason::NO_REASON;
JS::GCReason minorGCTriggerReason() const { return minorGCTriggerReason_; }
void clearMinorGCRequest() {
minorGCTriggerReason_ = JS::GCReason::NO_REASON;
bool shouldCollect() const;
bool isNearlyFull() const;
bool isUnderused() const;
bool enableProfiling() const { return enableProfiling_; }
bool addMapWithNurseryMemory(MapObject* obj) {
mapsWithNurseryMemory_.back() != obj);
return mapsWithNurseryMemory_.append(obj);
bool addSetWithNurseryMemory(SetObject* obj) {
setsWithNurseryMemory_.back() != obj);
return setsWithNurseryMemory_.append(obj);
// The amount of space in the mapped nursery available to allocations.
static const size_t NurseryChunkUsableSize =
gc::ChunkSize - sizeof(gc::ChunkBase);
void joinDecommitTask() { decommitTask.join(); }
mozilla::TimeStamp collectionStartTime() {
return startTimes_[ProfileKey::Total];
// Round a size in bytes to the nearest valid nursery size.
static size_t roundSize(size_t size);
gc::GCRuntime* const gc;
// Vector of allocated chunks to allocate from.
Vector<NurseryChunk*, 0, SystemAllocPolicy> chunks_;
// Pointer to the first unallocated byte in the nursery.
uintptr_t position_;
// These fields refer to the beginning of the nursery. They're normally 0
// and chunk(0).start() respectively. Except when a generational GC zeal
// mode is active, then they may be arbitrary (see Nursery::clear()).
unsigned currentStartChunk_;
uintptr_t currentStartPosition_;
// Pointer to the last byte of space in the current chunk.
uintptr_t currentEnd_;
// Pointer to the last byte of space in the current chunk, or nullptr if we
// are not allocating strings in the nursery.
uintptr_t currentStringEnd_;
// Pointer to the last byte of space in the current chunk, or nullptr if we
// are not allocating BigInts in the nursery.
uintptr_t currentBigIntEnd_;
// The index of the chunk that is currently being allocated from.
unsigned currentChunk_;
// The current nursery capacity measured in bytes. It may grow up to this
// value without a collection, allocating chunks on demand. This limit may be
// changed by maybeResizeNursery() each collection. It includes chunk headers.
size_t capacity_;
mozilla::TimeDuration timeInChunkAlloc_;
// Report minor collections taking at least this long, if enabled.
mozilla::TimeDuration profileThreshold_;
bool enableProfiling_;
// Whether we will nursery-allocate strings.
bool canAllocateStrings_;
// Whether we will nursery-allocate BigInts.
bool canAllocateBigInts_;
// Report how many strings were deduplicated.
bool reportDeduplications_;
// Whether and why a collection of this nursery has been requested. This is
// mutable as it is set by the store buffer, which otherwise cannot modify
// anything in the nursery.
mutable JS::GCReason minorGCTriggerReason_;
// Profiling data.
enum class ProfileKey {
#define DEFINE_TIME_KEY(name, text) name,
using ProfileTimes =
mozilla::EnumeratedArray<ProfileKey, ProfileKey::KeyCount,
using ProfileDurations =
mozilla::EnumeratedArray<ProfileKey, ProfileKey::KeyCount,
ProfileTimes startTimes_;
ProfileDurations profileDurations_;
ProfileDurations totalDurations_;
// Data about the previous collection.
struct PreviousGC {
JS::GCReason reason = JS::GCReason::NO_REASON;
size_t nurseryCapacity = 0;
size_t nurseryCommitted = 0;
size_t nurseryUsedBytes = 0;
size_t tenuredBytes = 0;
size_t tenuredCells = 0;
mozilla::TimeStamp endTime;
PreviousGC previousGC;
bool hasRecentGrowthData;
double smoothedGrowthFactor;
// Calculate the promotion rate of the most recent minor GC.
// The valid_for_tenuring parameter is used to return whether this
// promotion rate is accurate enough (the nursery was full enough) to be
// used for tenuring and other decisions.
// Must only be called if the previousGC data is initialised.
double calcPromotionRate(bool* validForTenuring) const;
// The set of externally malloced buffers potentially kept live by objects
// stored in the nursery. Any external buffers that do not belong to a
// tenured thing at the end of a minor GC must be freed.
BufferSet mallocedBuffers;
size_t mallocedBufferBytes = 0;
// During a collection most hoisted slot and element buffers indicate their
// new location with a forwarding pointer at the base. This does not work
// for buffers whose length is less than pointer width, or when different
// buffers might overlap each other. For these, an entry in the following
// table is used.
typedef HashMap<void*, void*, PointerHasher<void*>, SystemAllocPolicy>
ForwardedBufferMap forwardedBuffers;
// When we assign a unique id to cell in the nursery, that almost always
// means that the cell will be in a hash table, and thus, held live,
// automatically moving the uid from the nursery to its new home in
// tenured. It is possible, if rare, for an object that acquired a uid to
// be dead before the next collection, in which case we need to know to
// remove it when we sweep.
// Note: we store the pointers as Cell* here, resulting in an ugly cast in
// sweep. This is because this structure is used to help implement
// stable object hashing and we have to break the cycle somehow.
using CellsWithUniqueIdVector = Vector<gc::Cell*, 8, SystemAllocPolicy>;
CellsWithUniqueIdVector cellsWithUid_;
using NativeObjectVector = Vector<NativeObject*, 0, SystemAllocPolicy>;
NativeObjectVector dictionaryModeObjects_;
template <typename Key>
struct DeduplicationStringHasher {
using Lookup = Key;
static inline HashNumber hash(const Lookup& lookup) {
JS::AutoCheckCannotGC nogc;
HashNumber strHash;
// Include flags in the hash. A string relocation overlay stores either
// the nursery root base chars or the dependent string nursery base, but
// does not indicate which one. If strings with different string types
// were deduplicated, for example, a dependent string gets deduplicated
// into an extensible string, the base chain would be broken and the root
// base would be unreachable.
if (lookup->asLinear().hasLatin1Chars()) {
strHash = mozilla::HashString(lookup->asLinear().latin1Chars(nogc),
} else {
strHash = mozilla::HashString(lookup->asLinear().twoByteChars(nogc),
return mozilla::HashGeneric(strHash, lookup->zone(), lookup->flags());
static MOZ_ALWAYS_INLINE bool match(const Key& key, const Lookup& lookup) {
if (!key->sameLengthAndFlags(*lookup) ||
key->asTenured().zone() != lookup->zone() ||
key->asTenured().getAllocKind() != lookup->getAllocKind()) {
return false;
JS::AutoCheckCannotGC nogc;
if (key->asLinear().hasLatin1Chars()) {
return mozilla::ArrayEqual(key->asLinear().latin1Chars(nogc),
} else {
return EqualChars(key->asLinear().twoByteChars(nogc),
using StringDeDupSet =
HashSet<JSString*, DeduplicationStringHasher<JSString*>,
// deDupSet is emplaced at the beginning of the nursery collection and reset
// at the end of the nursery collection. It can also be reset during nursery
// collection when out of memory to insert new entries.
mozilla::Maybe<StringDeDupSet> stringDeDupSet;
// Lists of map and set objects allocated in the nursery or with iterators
// allocated there. Such objects need to be swept after minor GC.
Vector<MapObject*, 0, SystemAllocPolicy> mapsWithNurseryMemory_;
Vector<SetObject*, 0, SystemAllocPolicy> setsWithNurseryMemory_;
NurseryDecommitTask decommitTask;
#ifdef JS_GC_ZEAL
struct Canary;
Canary* lastCanary_;
NurseryChunk& chunk(unsigned index) const { return *chunks_[index]; }
// Set the current chunk. This updates the currentChunk_, position_
// currentEnd_ and currentStringEnd_ values as approprite. It'll also
// poison the chunk, either a portion of the chunk if it is already the
// current chunk, or the whole chunk if fullPoison is true or it is not
// the current chunk.
void setCurrentChunk(unsigned chunkno);
bool initFirstChunk(AutoLockGCBgAlloc& lock);
// extent is advisory, it will be ignored in sub-chunk and generational zeal
// modes. It will be clamped to Min(NurseryChunkUsableSize, capacity_).
void poisonAndInitCurrentChunk(size_t extent = gc::ChunkSize);
void setCurrentEnd();
void setStartPosition();
// Allocate the next chunk, or the first chunk for initialization.
// Callers will probably want to call setCurrentChunk(0) next.
MOZ_MUST_USE bool allocateNextChunk(unsigned chunkno,
AutoLockGCBgAlloc& lock);
MOZ_ALWAYS_INLINE uintptr_t currentEnd() const;
uintptr_t position() const { return position_; }
MOZ_ALWAYS_INLINE bool isSubChunkMode() const;
JSRuntime* runtime() const;
gcstats::Statistics& stats() const;
const js::gc::GCSchedulingTunables& tunables() const;
// Common internal allocator function.
void* allocate(size_t size);
void* moveToNextChunkAndAllocate(size_t size);
#ifdef JS_GC_ZEAL
void writeCanary(uintptr_t address);
struct CollectionResult {
size_t tenuredBytes;
size_t tenuredCells;
CollectionResult doCollection(JS::GCReason reason);
void doPretenuring(JSRuntime* rt, JS::GCReason reason,
bool highPromotionRate);
// Move the object at |src| in the Nursery to an already-allocated cell
// |dst| in Tenured.
void collectToFixedPoint(TenuringTracer& trc);
// The dependent string chars needs to be relocated if the base which it's
// using chars from has been deduplicated.
template <typename CharT>
void relocateDependentStringChars(JSDependentString* tenuredDependentStr,
JSLinearString* baseOrRelocOverlay,
size_t* offset,
bool* rootBaseNotYetForwarded,
JSLinearString** rootBase);
// Handle relocation of slots/elements pointers stored in Ion frames.
inline void setForwardingPointer(void* oldData, void* newData, bool direct);
inline void setDirectForwardingPointer(void* oldData, void* newData);
void setIndirectForwardingPointer(void* oldData, void* newData);
inline void setSlotsForwardingPointer(HeapSlot* oldSlots, HeapSlot* newSlots,
uint32_t nslots);
inline void setElementsForwardingPointer(ObjectElements* oldHeader,
ObjectElements* newHeader,
uint32_t capacity);
#ifdef DEBUG
bool checkForwardingPointerLocation(void* ptr, bool expectedInside);
// Updates pointers to nursery objects that have been tenured and discards
// pointers to objects that have been freed.
void sweep(JSTracer* trc);
// Reset the current chunk and position after a minor collection. Also poison
// the nursery on debug & nightly builds.
void clear();
void sweepDictionaryModeObjects();
void sweepMapAndSetObjects();
// Change the allocable space provided by the nursery.
void maybeResizeNursery(JSGCInvocationKind kind, JS::GCReason reason);
size_t targetSize(JSGCInvocationKind kind, JS::GCReason reason);
void clearRecentGrowthData();
void growAllocableSpace(size_t newCapacity);
void shrinkAllocableSpace(size_t newCapacity);
void minimizeAllocableSpace();
// Free the chunks starting at firstFreeChunk until the end of the chunks
// vector. Shrinks the vector but does not update maxChunkCount().
void freeChunksFrom(unsigned firstFreeChunk);
void sendTelemetry(JS::GCReason reason, mozilla::TimeDuration totalTime,
bool wasEmpty, double promotionRate);
void printCollectionProfile(JS::GCReason reason, double promotionRate);
void printDeduplicationData(js::StringStats& prev, js::StringStats& curr);
// Profile recording and printing.
void maybeClearProfileDurations();
void startProfile(ProfileKey key);
void endProfile(ProfileKey key);
static void printProfileDurations(const ProfileDurations& times);
mozilla::TimeStamp collectionStartTime() const;
mozilla::TimeStamp lastCollectionEndTime() const;
friend class TenuringTracer;
friend class gc::MinorCollectionTracer;
friend class jit::MacroAssembler;
friend struct NurseryChunk;
} // namespace js
#endif // gc_Nursery_h