On Tue, Feb 17, 2015 at 02:08:52PM +0100, Denys Vlasenko wrote:
> >> Please see attached file.
> >
> > I tried it and it's ~1 cycle slower for at least sizes 16-30;
> > presumably we're seeing the cost of the extra compare/branch at these
> > sizes but not at others. What does your timing test show?
> 
> See below.
> First column - result of my2.s
> Second column - result of vda1.s
> 
> Basically, the "rep stosq" code path got a bit faster, while
> small memsets stayed the same.

Can you post your test program for me to try out? Here's what I've
been using, attached.

Rich