Jakub's Recommendations for ia32 Support
P at draigBrady.com
Wed Feb 4 22:47:57 UTC 2009
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:
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 ?
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