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Re: [Patch, i386] Avoid LCP stalls (issue5975045)


On Wed, Apr 4, 2012 at 5:07 PM, Teresa Johnson <tejohnson@google.com> wrote:
> New patch to avoid LCP stalls based on feedback from earlier patch. I modified
> H.J.'s old patch to perform the peephole2 to split immediate moves to HImode
> memory. This is now enabled for Core2, Corei7 and Generic.
>
> I verified that this enables the splitting to occur in the case that originally
> motivated the optimization. If we subsequently find situations where LCP stalls
> are hurting performance but an extra register is required to perform the
> splitting, then we can revisit whether this should be performed earlier.
>
> I also measured SPEC 2000/2006 performance using Generic64 on an AMD Opteron
> and the results were neutral.
>

What are the performance impacts on Core i7? I didn't notice any significant
changes when I worked on it for Core 2.

Thanks.

-- 
H.J.


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