WTF_MAKE_NONCOPYABLE(CLoopStack);

public:

// Allow 8k of excess registers before we start trying to reap the stack

static constexpr ptrdiff_t maxExcessCapacity = 8 * 1024;

CLoopStack();

~CLoopStack();

bool ensureCapacityFor(Register* newTopOfStack);

bool containsAddress(Register* address) { return (lowAddress() <= address && address < highAddress()); }

static size_t committedByteCount();

void gatherConservativeRoots(ConservativeRoots&, JITStubRoutineSet&, CodeBlockSet&);

void sanitizeStack();

inline void* currentStackPointer() const

{

// One might be tempted to assert that m_currentStackPointer <= m_topCallFrame->topOfFrame()

// here. That assertion would be incorrect because this function may be called from function

// prologues (e.g. during a stack check) where m_currentStackPointer may be higher than

// m_topCallFrame->topOfFrame() because the stack pointer has not been initialized to point

// to frame top yet.

return m_currentStackPointer;

}

void setCurrentStackPointer(void* sp) { m_currentStackPointer = sp; }

size_t size() const { return highAddress() - lowAddress(); }

void setSoftReservedZoneSize(size_t);

bool isSafeToRecurse() const;

private:

StackManager& stackManager() const;

VM& vm() const;

Register* lowAddress() const

{

return m_end;

}

WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN

Register* highAddress() const

{

return reinterpret_cast_ptr<Register*>(static_cast<char*>(m_reservation.base()) + m_reservation.size());

}

WTF_ALLOW_UNSAFE_BUFFER_USAGE_END

Register* reservationTop() const

{

char* reservationTop = static_cast<char*>(m_reservation.base());

return reinterpret_cast_ptr<Register*>(reservationTop);

}

bool grow(Register* newTopOfStack);

void releaseExcessCapacity();

void addToCommittedByteCount(long);

void setCLoopStackLimit(Register* newTopOfStack);

// The following is always true:

// reservationTop() <= m_commitTop <= m_end <= m_currentStackPointer <= highAddress()

Register* m_end; // lowest address of JS allocatable stack memory.

Register* m_commitTop; // lowest address of committed memory.

PageReservation m_reservation;

void* m_lastStackPointer;

void* m_currentStackPointer;

ptrdiff_t m_softReservedZoneSizeInRegisters;

friend class LLIntOffsetsExtractor;