Re: likely, unlikely and builtin_expect()

[mohanlal jangir <mohanlal@xxxxxxxxxxx>]

> I understand the meaning of likely() and unlikely() in linux/compiler.h,
> but I don't undertand the meaning of !! in the definition.
>
> #define likely(x)       __builtin_expect(!!(x), 1)
> #define unlikely(x)     __builtin_expect(!!(x), 0)
>
> why not this?:
>
> #define likely(x)       __builtin_expect((x), 1)
> #define unlikely(x)     __builtin_expect((x), 0)
!!(x) ensures, the first argument to __builtin_expect is always 0 or 1 
regardless of input.

Regards,
Mohan 


--
Kernelnewbies: Help each other learn about the Linux kernel.
Archive:       http://mail.nl.linux.org/kernelnewbies/
FAQ:           http://kernelnewbies.org/faq/