} while (0)
#define count_trailing_zeros(count, x) \
do { \
UDItype __cbtmp; \
ASSERT ((x) != 0); \
__asm__ ("bsfq %1,%0" : "=r" (count) : "rm" ((UDItype)(x))); \
__asm__ ("bsfq %1,%0" : "=r" (__cbtmp) : "rm" ((UDItype)(x))); \
(count) = __cbtmp; \
#endif /* x86_64 */