On Tue, 2007-11-20 at 21:56 +0800, Herbert Xu wrote:
> [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.
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