Jakub's Recommendations for ia32 Support

[Bill Nottingham]

Ulrich Drepper (drepper at redhat.com) said: 
> The Atom core has nothing to do with the Core2 or P4 or any other core.
>  Whoever told you Prescott is optimal doesn't know what s/he's talking
> about.  All cores after the i586 are out-of-order cores, the Atom is an
> in-order.  This should show you how silly that statement is.
> 
> We are still waiting for Intel to disclose the details about the
> micro-architecture.  There is no backend support in gcc yet.

Right, the main goal of my playing was to see if telling gcc to
tune for i586 (another in-order core) would help on Atom as
an accident/side-effect, without detailed knowledge of atom. It
does not.

(In fact, on the processors I tested (Athlon64, Core2Duo, Atom),
the effects of -mtune=generic vs -mtune=i686 vs -mtune=i586 were
pretty much identical across all of them.)

Bill