fls64
ia_conf->prefix_len = 64 - fls64(hi_counter);
ia_conf->prefix_len = 128 - fls64(lo_counter);
int fls64(uint64_t);
len = fls64((n << 6) + (~imms & 0x3f)) - 1;
len = fls64((n << 6) + (~imms & 0x3f)) - 1;
tmp = DIV_ROUND_UP(fls64(tmp) - 1, 9) - 1;
*frag = min_t(unsigned int, ffs(start) - 1, fls64(end - start) - 1);
above = fls64(__sync_branch_prefix(p, id) ^ p->prefix);
for (pot = fls64(hole_end - 1) - 1;
__func__, pot, fls64(hole_end - 1) - 1)) {