3955   mchunkptr oldfirst = align_as_chunk(oldbase);  in prepend_alloc()  local
3956   size_t psize = (char*)oldfirst - (char*)p;  in prepend_alloc()
3961   assert((char*)oldfirst > (char*)q);  in prepend_alloc()
3962   assert(pinuse(oldfirst));  in prepend_alloc()
3966   if (oldfirst == m->top) {  in prepend_alloc()
3972   else if (oldfirst == m->dv) {  in prepend_alloc()
3978     if (!is_inuse(oldfirst)) {  in prepend_alloc()
3979       size_t nsize = chunksize(oldfirst);  in prepend_alloc()
3980       unlink_chunk(m, oldfirst, nsize);  in prepend_alloc()
3981       oldfirst = chunk_plus_offset(oldfirst, nsize);  in prepend_alloc()
3984     set_free_with_pinuse(q, qsize, oldfirst);  in prepend_alloc()