Re: [RFC] Selective scheduling pass

["Steven Bosscher" <stevenb.gcc@gmail.com>]

(xf. http://gcc.gnu.org/ml/gcc-patches/2008-06/msg00114.html)

Hi Andrey,

Thanks for this very nice work.  I was wondering if you could say a
little more about the performance impact of the selective scheduler on
the generated code...

You posted SPEC scores and there are as many ups as there are downs in
there.  Where do the regressions come from?  The 3-5% on e.g. galgel
and vortex are quite substantial slowdowns, but do you know why they
happen?

Also, you post a new scheduler and a set of target tunings in one set
of patches.  I would like to know what the performance impact is of
just the target changes alone.  That is, what happens to e.g. SPEC
scores for ia64 with just the tweaks and tunings patch
(http://gcc.gnu.org/ml/gcc-patches/2008-06/msg00117.html)?  I assume
those target changes alone (the ones not related to sel-sched) also
have a positive performance impact.  Since you've globbed everything
into one patch set, it's impossible to tell how much of the
performance changes can be attributed to sel-sched, and how much is
just target tweaks...

Gr.
Steven