RFB: patch to fix PR37534
Luis Machado
luisgpm@linux.vnet.ibm.com
Tue Nov 11 15:31:00 GMT 2008
Vladimir,
The results look good. There's overall improvement for CPU2K, and some
small one digit degradations here and there for a few INT benchmarks
(some are probably noise).
Facerec is up around 22% for 32-bit and 23% for 64-bit.
32-bit
INT base: -0.12%
INT peak: -0.56%
FP base: 2.08%
FP peak: 1.89%
Overall INT: -0.34%
Overall FP: 1.99%
Overall: 0.82%
64-bit
INT base: -0.49%
INT peak: 0.05%
FP base: 3.46%
FP peak: 1.39%
Overall INT: -0.22%
Overall FP: 2.42%
Overall: 1.09%
Thanks,
Luis
On Mon, 2008-11-10 at 15:25 -0200, Luis Machado wrote:
> Thanks Vladimir. I'll give it a try and will report back.
>
> Regards,
> Luis
>
> On Mon, 2008-11-10 at 12:13 -0500, Vladimir Makarov wrote:
> > Hi, Luis.
> >
> > Could you test the following patch. It uses another spill heuristic.
> > Usually spill priority is spill cost divided by # of left conflicts for
> > the corresponding node in the graph. Some RA literature mentions
> > division by #left conflicts in power 2. The patch uses a heuristic
> > close to the second one. I don't know why but instead of 17%
> > degradation it gives 10% improvement on facerec (for -O2 -mtune=power6).
> >
> > Actually I tried many things to solve the problem:
> >
> > o different coalescing algorithms (iterative and optimistic ones)
> >
> > o usage of union of cover classes for pseudos. This is one drawback I
> > see in IRA with comparison with the old RA. When pseudo is used only
> > for transferring memory value (r<-m ... m<-r), it can be done through
> > float or integer registers. When coloring is not possible for one class
> > (e.g. integer registers) we could use another class (e.g. float registers).
> >
> > o using coloring with different spill heuristics and choosing the best
> > one (Bernstein's approach)
> >
> > o different spill heuristics in reload.
> >
> > But the best result is achieved by this patch which is ironically the
> > simplest one.
> >
> > In general the patch does not improve overall SPEC rates on other
> > platforms. Because of NP-complete nature of RA, I don't believe that we
> > can achieve better IRA behaviour on all tests but I think we should
> > achieve not worse overall SPEC results.
> >
> >
> >
>
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