__bitcount64
count += __bitcount64(bitmask_range(*addr, bit0, bound));
count += __bitcount64(bitmask_range(*addr, 0, bound));
#define bitcount64(x) __bitcount64((uint64_t)(x))
#define __bitcountl(x) __bitcount64((unsigned long)(x))
#define bitcount64(x) __bitcount64((uint64_t)(x))