Re: [RFC][PATCH 01/10] put alignment macros in align.h

Dave Hansen
2006-08-30T16:48:49Z

On Wed, 2006-08-30 at 20:11 +0400, Nikita Danilov wrote:
> Dave Hansen writes:
> > + */
> > +#ifndef __ASSEMBLY__
> > +#define ALIGN(x,a) (((x)+(a)-1)&~((a)-1))
>
> This evaluates (a) twice. While in all existing call-sites (a) is
> probably a constant, it's still safer to do
>
> #define ALIGN(x,a) ({ typeof(a) __a = (a); (((x) + __a - 1) & ~(__a - 1)); })
>
> in a generic macro and rely on compiler to optimize temporary variable
> out.

Looks great to me. I'll incorporate it for the next version.

-- Dave