Re: [PATCH, PR 54394] Compute loops when generating inline summaries

[Martin Jambor <mjambor at suse dot cz>]

On Fri, Aug 31, 2012 at 10:53:32AM +0200, Jan Hubicka wrote:
> > Hi,
> > 
> > the patch below fixes PR 54394.  The problem is that since revision
> > 190346 we depend on bb->loop_father being non-NULL to get loop_depth.
> > However, with loops not computed, the loop_father is NULL, loop_depth
> > is thus considered zero and call graph edges out of such BB can be
> > considered much cooler, leading to inlining regressions.
> > 
> > This patch fixes that by recomputing loops whenever optimizing, not
> > only for loop bounds hints.  We might put the computation elsewhere or
> > do it only under more restrictive circumstances, but I believe that
> > after rev. 190346 we have to do it.  In particular, I am not sure
> > whether we had (semi)correct loop_depths when doing early inlining or
> > not, this patch re-calculates it for early inliner too.
> > 
> > Bootstrapped and tested on x86_64-linux, fixes fatigue run-time on
> > an x86_64-linux and i686-linux for me.  What do you think?
> > 
> > Thanks,
> > 
> > Martin
> > 
> > 
> > 2012-08-29  Martin Jambor  <mjambor@suse.cz>
> > 
> > 	PR middle-end/54394
> > 	* ipa-inline-analysis.c (estimate_function_body_sizes): Compute
> > 	dominance info and loops whenever optimizing.
> > 
> > 
> > Index: src/gcc/ipa-inline-analysis.c
> > ===================================================================
> > --- src.orig/gcc/ipa-inline-analysis.c
> > +++ src/gcc/ipa-inline-analysis.c
> > @@ -2102,6 +2102,11 @@ estimate_function_body_sizes (struct cgr
> >    info->conds = 0;
> >    info->entry = 0;
> >  
> > +  if (optimize)
> 
> This is OK. I think you can also skip thi computation for early inlining
> where we don't do any hints, so probably if (optimize && !early)
> 
> Honza

This is not required to make hints working, it is necessary because of
the following line a in estimate_function_body_sizes:

	      es->loop_depth = bb_loop_depth (bb);

which always yields zero if we don't have loops computed.  So I can
skip the computation only if we don't care about loop depths in early
inlining either.  Should I skip it?

Thanks,

Martin