[PATCH] Enabling Software Prefetching by Default at -O3

[Richard Guenther]

On Thu, 24 Jun 2010, Fang, Changpeng wrote:

> Hi, 
> 
> Attached is the version of the patch that turns prefetching on at -O3 for AMD cpus
> only. As discussed elsewhere in this thread, we use tri-state for -fprefetch-loop-arrays.
> If this flag is not explicitly set,  (for -O3) we turn it on in gcc/config/i386/i386.c 
> (override_options).
> 
> Is this OK to commit now?

Ok.

Thanks,
Richard.

> 
> Thanks, 
> 
> Changpeng
> 
> ________________________________________
> From: Mark Mitchell [mark@codesourcery.com]
> Sent: Saturday, June 19, 2010 3:05 PM
> To: Christian Borntraeger
> Cc: gcc-patches@gcc.gnu.org; H.J. Lu; Fang, Changpeng; rguenther@suse.de; sebpop@gmail.com; Zdenek Dvorak; Maxim Kuvyrkov
> Subject: Re: [PATCH] Enabling Software Prefetching by Default at -O3
> 
> Christian Borntraeger wrote:
> 
> > It also might be worth to investigate if overriding the parameters per
> > -mtune=XXX results in an overall win for -fprefetch-loop-arrays. We did
> > that on s390 since the default values were not ideal
> 
> Yes, that might be a good idea for i7.
> 
> But, in the meantime, I think we should get a version of the patch that
> turns on prefetching on AMD CPUs with -O3.  There's no reason to demand
> consistency for all CPUs and it clearly benefits the AMD CPUs.
> Changpeng, would you please submit a patch that activates this
> optimization only with tuning for AMD CPUs?
> 
> Thanks,
> 
> --
> Mark Mitchell
> CodeSourcery
> mark@codesourcery.com
> (650) 331-3385 x713
> 
> 

-- 
Richard Guenther <rguenther@suse.de>
Novell / SUSE Labs
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