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Re: Merging tuples branch into mainline today
> Jan Hubicka wrote:
> >So while the passes are probably now well in "benchmark toy" category
> >and they will need many changes to be useful in general, I think it is
> >good to have something we can test the framework at.
>
> Do these passes actually help on benchmarks?
Yes, those help signifcandly to SPEC2000 ART benchmark and some others.
I didn't mean benchmark toy too mismissively here though, I like the
idea overall and think there is great potential in this kind of
transforms. Clearly for C++ we need optimization passes that reorganize
the datastructure layout, are able to remove unnecesary abstraction and
such. Ayal was mentioning struct reorg with hand tweaked escape analysis
actualy can make over 10% improvement on some http server.
The problem however is that with current strength of type-escape, lack
of alias and points-to info and link time optimization, the passes
themselves are not helping much real world applications. So I don't
think we need to see them as major showstoppers for projects like tuples
that actually makes LTO possible. At the same time I don't think they
should be dropped completely. Lets just concentrate on infrastructure
and update them as needed.
Honza
>
> I don't think we should be dismissive of "benchmark toy" passes if they
> actually improve benchmarks significantly. We don't have to like it,
> but we should accept that people are going to benchmark GCC against its
> proprietary competition, and that having good benchmark results matters.
>
> Thanks,
>
> --
> Mark Mitchell
> CodeSourcery
> mark@codesourcery.com
> (650) 331-3385 x713