On Tue, 2007-11-20 at 21:56 +0800, Herbert Xu wrote:
quoted text
> [KERNEL]: Avoid divide in IS_ALIGN
> I was happy to discover the brand new IS_ALIGN macro and quickly
> used it in my code.  To my dismay I found that the generated code
> used division to perform the test.
> This patch fixes it by changing the % test to an &.  This avoids
> the division.

Perhaps this should use is_power_of_2?

#define IS_ALIGNED(x, a) 				\
	({ typeof(x) _a = (typeof(x))(a); 		\
	   is_power_of_2(_a) ? (((x) & (_a - 1)) == 0)	\
			     : (((x) % _a == 0); })

gcc -o2/oS seems to do the right thing.

-
unsubscribe notice
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/