Polyhedron Benchmark

[Uros Bizjak]

Hello!

> > Could you perhaps add -fvect-cost-model to
> > gcc-4.3 compile flags? There are some surprises there ;)
>
> Well, a 2% overall improvement, some slower, some faster. Only for
> induct an improvement by a 1/3.
>
> Should I use -fvect-cost-model in general for my nightly runs or should
> I add another column with one -fvect-cost-model run?
>   

I think that polyhedron could be a nice head-to-head comparison for 
builds with and without -fvect-cost-model. Since I expect that there 
will be quite some work needed to tune the vectorizer - and if you can 
spare some cycles - I'd propose to add another column to the table.

BTW: Looking at your benchmark page, you have links to some stalled PRs 
there. PR32457 was fixed some time ago and PR32084 (and IMO also 32086) 
is due to "vectorize-all-or-nothing" approach implemented by current 
vectorizer (should be fixed by -fvect-cost-model).

> For Core2 the results with -fvect-cost-model are:
>   

I _think_ that on K8, the difference was even larger (current X86_64 
vect cost model is written for K8, not Core2), but it was some time ago 
that I have played with this option.

Uros.