__bf_shf
#define __bf_shf(x) (__builtin_ffsll(x) - 1)
#define __bf_shf(x) (__builtin_ffsll(x) - 1)
#define __bf_shf(x) (__builtin_ffsll(x) - 1)
#define __bf_shf(x) (__builtin_ffsll(x) - 1)
#define __bf_shf(x) (__builtin_ffsll(x) - 1)