JSStack::JSStack(VM& vm, size_t capacity)
: m_vm(vm)
, m_end(0)
, m_topCallFrame(vm.topCallFrame)
{
ASSERT(capacity && isPageAligned(capacity));
m_reservation = PageReservation::reserve(roundUpAllocationSize(capacity * sizeof(Register), commitSize), OSAllocator::JSVMStackPages);
updateStackLimit(highAddress());
m_commitEnd = highAddress();
m_lastStackTop = getBaseOfStack();
disableErrorStackReserve();
m_topCallFrame = 0;
}
bool JSStack::growSlowCase(Register* newEnd)
{
if (newEnd <= m_commitEnd) {
m_end = newEnd;
return true;
}
long delta = roundUpAllocationSize(reinterpret_cast<char*>(newEnd) - reinterpret_cast<char*>(m_commitEnd), commitSize);
if (reinterpret_cast<char*>(m_commitEnd) + delta > static_cast<char*>(m_reservation.base()) + m_reservation.size())
return false;
m_reservation.commit(m_commitEnd, delta);
addToCommittedByteCount(delta);
m_commitEnd = reinterpret_cast_ptr<Register*>(reinterpret_cast<char*>(m_commitEnd) + delta);
m_end = newEnd;
return true;
}
void RegisterFile::releaseExcessCapacity()
{
#if OS(QNX)
size_t sizeForGlobals = roundUpAllocationSize(m_maxGlobals * sizeof(Register), commitSize);
Register *endOfGlobals = reinterpret_cast<Register*>(reinterpret_cast<char*>(m_buffer) + sizeForGlobals);
size_t decommitSize = (m_max - endOfGlobals) * sizeof(Register);
if (decommitSize > 0) {
if (mmap(endOfGlobals, decommitSize, PROT_NONE, MAP_FIXED|MAP_LAZY|MAP_PRIVATE|MAP_ANON, -1, 0) == MAP_FAILED)
fprintf(stderr, "Could not decommit register file memory: %d\n", errno);
}
m_commitEnd = endOfGlobals;
#elif HAVE(MMAP) && HAVE(MADV_FREE) && !HAVE(VIRTUALALLOC)
while (madvise(m_start, (m_max - m_start) * sizeof(Register), MADV_FREE) == -1 && errno == EAGAIN) { }
#elif HAVE(VIRTUALALLOC)
VirtualFree(m_start, (m_max - m_start) * sizeof(Register), MEM_DECOMMIT);
m_commitEnd = m_start;
#endif
m_maxUsed = m_start;
}
bool JSStack::growSlowCase(Register* newEnd)
{
// If we have already committed enough memory to satisfy this request,
// just update the end pointer and return.
if (newEnd >= m_commitEnd) {
updateStackLimit(newEnd);
return true;
}
// Compute the chunk size of additional memory to commit, and see if we
// have it is still within our budget. If not, we'll fail to grow and
// return false.
long delta = roundUpAllocationSize(reinterpret_cast<char*>(m_commitEnd) - reinterpret_cast<char*>(newEnd), commitSize);
if (reinterpret_cast<char*>(m_commitEnd) - delta <= reinterpret_cast<char*>(m_useableEnd))
return false;
// Otherwise, the growth is still within our budget. Go ahead and commit
// it and return true.
m_reservation.commit(reinterpret_cast<char*>(m_commitEnd) - delta, delta);
addToCommittedByteCount(delta);
m_commitEnd = reinterpret_cast_ptr<Register*>(reinterpret_cast<char*>(m_commitEnd) - delta);
updateStackLimit(newEnd);
return true;
}
