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RE: [RFC] [PATCH, i386] Adjust unroll factor for bdver3 and bdver4


> I suggest you add this to x86-tune.def and enable it for
> bdver3 and bdver4.

The macro TARGET_LOOP_UNROLL_ADJUST is not new. It is already available and is used by target s390.
Since it is not an "x86 only" feature I didn't add that in x86-tune.def.

Regards
Ganesh

-----Original Message-----
From: H.J. Lu [mailto:hjl.tools@gmail.com] 
Sent: Thursday, November 21, 2013 12:02 AM
To: Gopalasubramanian, Ganesh
Cc: gcc-patches@gcc.gnu.org; Uros Bizjak (ubizjak@gmail.com); Richard Guenther <richard.guenther@gmail.com> (richard.guenther@gmail.com); borntraeger@de.ibm.com; Jakub Jelinek (jakub@redhat.com)
Subject: Re: [RFC] [PATCH, i386] Adjust unroll factor for bdver3 and bdver4

On Wed, Nov 20, 2013 at 10:26 AM, Gopalasubramanian, Ganesh <Ganesh.Gopalasubramanian@amd.com> wrote:
> Hi,
>
> Steamroller processors contain a loop predictor and a loop buffer, which may make unrolling small loops less important.
> When unrolling small loops for steamroller, making the unrolled loop fit in the loop buffer should be a priority.
>
> This patch uses a heuristic approach (number of memory references) to decide the unrolling factor for small loops.
> This patch has some noise in SPEC 2006 results.
>
> Bootstrapping passes.
>
> I would like to know your comments before committing.
>

I suggest you add this to x86-tune.def and enable it for
bdver3 and bdver4.



--
H.J.



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