void QListData::realloc(int alloc)
{
Q_ASSERT(d->ref == 1);
d = static_cast<Data *>(qRealloc(d, DataHeaderSize + alloc * sizeof(void *)));
d->alloc = alloc;
if (!alloc)
d->begin = d->end = 0;
}
void *qReallocAligned(void *oldptr, size_t newsize, size_t oldsize, size_t alignment)
{
// fake an aligned allocation
Q_UNUSED(oldsize);
void *actualptr = oldptr ? static_cast<void **>(oldptr)[-1] : 0;
if (alignment <= sizeof(void*)) {
// special, fast case
void **newptr = static_cast<void **>(qRealloc(actualptr, newsize + sizeof(void*)));
if (!newptr)
return 0;
if (newptr == actualptr) {
// realloc succeeded without reallocating
return oldptr;
}
*newptr = newptr;
return newptr + 1;
}
// qMalloc returns pointers aligned at least at sizeof(size_t) boundaries
// but usually more (8- or 16-byte boundaries).
// So we overallocate by alignment-sizeof(size_t) bytes, so we're guaranteed to find a
// somewhere within the first alignment-sizeof(size_t) that is properly aligned.
// However, we need to store the actual pointer, so we need to allocate actually size +
// alignment anyway.
void *real = qRealloc(actualptr, newsize + alignment);
if (!real)
return 0;
quintptr faked = reinterpret_cast<quintptr>(real) + alignment;
faked &= ~(alignment - 1);
void **faked_ptr = reinterpret_cast<void **>(faked);
// now save the value of the real pointer at faked-sizeof(void*)
// by construction, alignment > sizeof(void*) and is a power of 2, so
// faked-sizeof(void*) is properly aligned for a pointer
faked_ptr[-1] = real;
return faked_ptr;
}
void QListData::realloc(int alloc)
{
Q_ASSERT(d->ref == 1);
Data *x = static_cast<Data *>(qRealloc(d, DataHeaderSize + alloc * sizeof(void *)));
if (!x)
qFatal("QList: Out of memory");
d = x;
d->alloc = alloc;
if (!alloc)
d->begin = d->end = 0;
}
QVectorData *QVectorData::reallocate(QVectorData *x, int newsize, int oldsize, int alignment)
{
if (alignment > alignmentThreshold())
return static_cast<QVectorData *>(qReallocAligned(x, newsize, oldsize, alignment));
return static_cast<QVectorData *>(qRealloc(x, newsize));
}
