Re: Improved Swaping Method In sort.c

[Ray Lee]

On Wed, Apr 30, 2008 at 11:09 AM, Soumyadip Das Mahapatra
<dip_kernel@xxxxxxxxxxx> wrote:
> Thanks Jan,
>  Actually it should be
>  static void u32_swap(void *a, void *b)
>  {
>     *(u32 *)b ^= *(u32 *)a;
>     *(u32 *)a ^= *(u32 *)b;
>     *(u32 *)b ^= *(u32 *)a;
>  }
>  But this code saves memory equaling two integers. What about that ?

The above prevents gcc from storing the intermediary in a register. So
you're trading fast register access for slow memory access.

Really, you shouldn't be prosing optimizations unless you do two
things: check the output of gcc (on at least one platform, but really
should be several), and include timings of before/after.
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