[PATCH] D21560: Relax the clearance calculating for breaking partial register dependency.

[Dehao Chen via llvm-commits]

On Tue, Jun 28, 2016 at 9:04 AM, Sanjay Patel <spatel at rotateright.com>
wrote:

> spatel accepted this revision.
> spatel added a comment.
> This revision is now accepted and ready to land.
>
> In http://reviews.llvm.org/D21560#468552, @danielcdh wrote:
>
> > I just tested the perf impact of this patch for SPECCPU INT2006
> benchmarks (perf test were done on sandybridge):
> >
> > 400.perlbench 2.21%
> >  401.bzip2    -0.46%
> >  403.gcc      1.59%
> >  429.mcf      1.79%
> >  445.gobmk    1.52%
> >  456.hmmer    1.63%
> >  458.sjeng    5.62%
> >  462.libquantum       1.54%
> >  464.h264ref  -1.28%
> >  471.omnetpp  0.00%
> >  473.astar    2.35%
> >  483.xalancbmk        -0.27%
> >  overall      1.29%
>
>
> That is a surprisingly large gain. This raises the question: if 64 is
> good, is 128 even better?
>

Tried with 128, the perf diff does not seems to be out of noise range. Thus
let's stick to 64.


>
> > About the -Oz issue, I agree that there should be no xor inserted at
> -Oz. But that's a different issue and should be fixed in a separate patch.
>
>
> Agreed. Please let me know if you plan to follow-up on that part.
>
> I have no further comments on this patch, so LGTM.
>

Thanks, as the original author (stoklund) of the number "16" has not
responded, and he seems to be inactive since one year ago, I'll go ahead
submit the patch.

Dehao


>
>
> http://reviews.llvm.org/D21560
>
>
>
>
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