upad64_t
upad64_t sem_pad1[3]; /* reserved for a mutex_t */
upad64_t sem_pad2[2]; /* reserved for a cond_t */
upad64_t pad1[3]; /* reserved for a mutex_t */
upad64_t pad2[2]; /* reserved for a cond_t */
upad64_t data; /* optional data */
upad64_t owner64;
upad64_t data;
upad64_t data;
upad64_t __pthread_mutex_owner64;
upad64_t __pthread_mutex_data;
upad64_t __pthread_cond_data;
upad64_t __pthread_barrier_cycle;
upad64_t __pthread_barrier_reserved;
upad64_t __pthread_once_pad[4];