Re: RFA: remove doubles in IRA

[Vladimir Makarov <vmakarov at redhat dot com>]

Jeff Law wrote:
> Vladimir Makarov wrote:
> > The following patch removes usage of doubles in IRA.  H.J. reported 
> > compare failure on x86 bootstrap.   I can not reproduce it but it was 
> > always a result of usage doubles whose value migrates from fp regs to 
> > memory and vice versus.
> >
> > I hope the patch solves the problem. H.J. I am going to commit it 
> > into ira-merge-branch soon.
> >
> > The patch was successfully bootstrapped on x86 and x86_64 with -O2 
> > and -O0.
> >
> > 2008-09-19  Vladimir Makarov  <vmakarov@redhat.com>
> >
> >    * ira-color.c (start_allocno_priorities): Rename to
> >    setup_allocno_priorities.  Use costs and
> >    ALLOCNO_EXCESS_PRESSURE_POINTS_NUM instead of frequencies and
> >    range lengths.  Get rid off doubles.
> >    (ira_fast_allocations): Call start_allocno_priorities.
> Presumably this can have minor effects on the relative priorities of 
> the allocnos and thus could have some effect on performance of the 
> code we generate.  Assuming that's the case, I'll conditionally 
> approve the patch -- if we see significant systemic performance issues 
> we'll obviously have to look at a different scheme.  I obviously 
> expect you'll be on the lookout for any such problems.
Thanks, Jeff.  I check SPEC2000 performance on x86 and power6 for my 
changes in IRA if there is a possibility for any generated code change.  
There was no visible change in code performance for this patch.  The 
patch also tries to calculate priorities as accurate as possible for int 
(scaling max cost close to INT_MAX).