Re: [lra] 3rd patch to speed more compilation of PR54146

[Vladimir Makarov <vmakarov at redhat dot com>]

On 10/09/2012 01:06 PM, Richard Guenther wrote:
> On Tue, Oct 9, 2012 at 6:10 PM, Vladimir Makarov <vmakarov@redhat.com> wrote:
> > On 10/08/2012 05:14 PM, Steven Bosscher wrote:
> > > On Mon, Oct 8, 2012 at 10:26 PM, Vladimir Makarov <vmakarov@redhat.com>
> > > wrote:
> > >
> > > > So I checked it on big file with > hundred functionson Intel machine and
> > > > got
> > > >
> > > > before a part of the patch implementing the insn stack as sbitmap
> > > > real=243.40 user=241.61 system=1.00
> > > >
> > > > after the part of the patch:
> > > > real=244.89 user=243.02 system=0.96
> > > Is that more than just noise, you think? A ~1.5s difference on ~240
> > > total isn't very much. I measured the timings on my set of cc1-i
> > > files, and sometimes the without-patch compiler was faster by a tiny
> > > amount, and sometimes it was slower. Even on an average of 10 runs I
> > > really couldn't say that the patch was a win or loss on the whole.
> > >
> > > I measured this on a mostly idle machine at home, not gcc17, which
> > > seems to be even more busy than usual lately, thanks to you and me :-)
> > Sorry, Steven.  It was a noise.  I ran it again now 3 times  and found that
> > was a noise.
> >
> > After some thinking, I realized that sbitmap is really the best
> > representation for this particular case.  That is because at the 1st
> > constraint pass we have all bits are set as we process *all* insns on the
> > 1st pass.  So sbitmap (at least before the extension and if we have pretty
> > compact UIDs) will be always smaller than bitmap.
> >
> > I committed the following your patch to the branch (as rev. 192264).
> >
> > And again, sorry for the false conclusions.
> Btw, congratulations for all the speedups (even though they probably
> are noise for "regular" programs?)!  I'm looking forward to the
> merge of LRA for x86 now.
Thanks, Richard.  Many thanks to Steven too.

I think I'll do merging in a week as I need to address proposals from 
the reviews (some of them needs good testing).