SINGLE_UNWIND
if (single_thread_set(p, SINGLE_UNWIND | SINGLE_DEEP))
single_thread_set(p, SINGLE_UNWIND);
single_thread_set(p, SINGLE_UNWIND | SINGLE_DEEP);
single_thread_set(p, SINGLE_UNWIND);
case SINGLE_UNWIND:
single_thread_set(p, SINGLE_UNWIND);
single_thread_set(p, SINGLE_UNWIND | SINGLE_DEEP);