Ulrich Drepper wrote:
Pádraig Brady wrote:
> -march=i686 is better than i586, but is it the best.
> I though -march=prescott was optimal for atom?
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.
I had a quick look and the consensus at the moment
for atom optimized CLFAGS is -march=prescott, but that's
really due to that being the most appropriate flag for
commonly available gcc at the time people were looking at it:
http://forums.gentoo.org/viewtopic-p-5127497.html
Intel have said that the Atom is merom (core2) ISA compliant,
and also that it's an in-order core. So perhaps the optimum
flags at present are: -march=core2 -mtune=i586 ?
cheers,
Pádraig.