__BIT_COUNT
#define BIT_COUNT(_s, p) __BIT_COUNT(_s, p)
#define CPU_COUNT(p) ((int)__BIT_COUNT(CPU_SETSIZE, p))
#define CPU_COUNT_S(_s, p) ((int)__BIT_COUNT((_s) * 8, p))
#define DOMAINSET_COUNT(p) ((int)__BIT_COUNT(DOMAINSET_SETSIZE, p))