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Re: [PATCH] Atom: Enabling unroll at O2 optimization level


Richard Guenther <richard.guenther@gmail.com> writes:
>
> 5% is not moderate.  Your patch does enable unrolling at -O2 but not -O3,
> why? Why do you disable register renaming?  check_imull requires a function
> comment.
>
> This completely looks like a hack for EEMBC2.0, so it's definitely not ok.
>
> -O2 is not supposed to give best benchmark results.

Besides it is against the Intel Optimization Manual recommendation
to prefer small code on Atom to avoid falling out of the predecode hints
in the cache.

So would need much more benchmarking on macro workloads first at least.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only


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