// splice in record, fill in offset.
		rec.special.offset = uint16(offset)
		rec.special.kind = _KindSpecialPinCounter
		rec.special.next = *ref
		*ref = (*special)(unsafe.Pointer(rec))
		spanHasSpecials(span)
	} else {
		rec = (*specialPinCounter)(unsafe.Pointer(*ref))
	}
	rec.counter++
}

// decPinCounter decreases the counter. If the counter reaches 0, the counter

	_      sys.NotInHeap
	next   *special // linked list in span
	offset uint16   // span offset of object
	kind   byte     // kind of special
}

// spanHasSpecials marks a span as having specials in the arena bitmap.
func spanHasSpecials(s *mspan) {
	arenaPage := (s.base() / pageSize) % pagesPerArena
	ai := arenaIndex(s.base())
	ha := mheap_.arenas[ai.l1()][ai.l2()]