> Hi,
>
> On Mon, Feb 11 2019, Jan Hubicka wrote:
> >> Hi.
> >>
> >> IPA pure const should always construct ipa_reduced_postorder with
> >> possibility to cross AVAIL_INTERPOSABLE boundary. The pass itself
> >> can then properly stop propagation on these symbols.
> >>
> >> The patch is pre-approved by Honza.
> >> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> >>
> >> Thanks,
> >> Martin
> >>
> >> gcc/ChangeLog:
> >>
> >> 2019-02-08 Martin Liska <mli...@suse.cz>
> >>
> >> PR ipa/89009
> >> * ipa-cp.c (build_toporder_info): Remove usage of a param.
> >> * ipa-inline.c (inline_small_functions): Likewise.
> >> * ipa-pure-const.c (propagate_pure_const): Likewise.
> >> (propagate_nothrow): Likewise.
> >> * ipa-reference.c (propagate): Likewise.
> >> * ipa-utils.c (struct searchc_env): Remove unused field.
> >> (searchc): Always search across AVAIL_INTERPOSABLE.
> >> (ipa_reduced_postorder): Always allow AVAIL_INTERPOSABLE as
> >> the only called IPA pure const can properly not propagate
> >> across interposable boundary.
> >> * ipa-utils.h (ipa_reduced_postorder): Remove param.
> >> @@ -105,7 +104,7 @@ searchc (struct searchc_env* env, struct cgraph_node
> >> *v,
> >>
> >> if (w->aux
> >> && (avail > AVAIL_INTERPOSABLE
> >> - || (env->allow_overwritable && avail == AVAIL_INTERPOSABLE)))
> >> + || avail == AVAIL_INTERPOSABLE))
>
> This looks a tad too mechanical, surely
>
> (avail > AVAIL_INTERPOSABLE || avail == AVAIL_INTERPOSABLE)
>
> can be simplified into just one comparison :-)
>
> >> {
> >> w_info = (struct ipa_dfs_info *) w->aux;
> >> if (w_info->new_node)
> >
> > This optimizes >= AVAIL_INTERPOSABLE then, but for ipa-cp, ipa-inline,
> > ipa-pure-const we do not want interposable calls to close SCC regions
> > (because we can not propagate here). ipa-reference is more subtle -
> > interposable calls close SCC regions IFF they are declared leaf.
> >
> > Can you, please, update ignore_edge_p of indiviual optimization passes
> > this way? (I.e. for all but ipa-reference add aval <= AVAIL_INTERPOSABLE
> > check for the availability of the target function and for ipa-reference
> > test also leaf attribute?).
>
> At least IPA-CP does not have any ignore_edge_p... does it really need
> any? Such node can incur an extra iteration of the propagator over an
You probably want to ignore edges with no useful jump functions to get
finer SCC structure as well.
> entire SCC, that is true, but is it worth adding a callback? Are SCCs
> with an interposable node common?
In a PIC library without visibility attributes it would be all of them.
Yep, this is mostly about quality of implementation - with SCCs bigger
than necessary code will work, just produce worse code.
Honza
>
> >
> > In all those cases we also want to check that given optimization pass is
> > enabled for both caller and callee. In other cases we do not want to
> > consider them part of SCCs as well. It may make sense to do this as one
> > change or I can do that incrementally.
>
> Likewise.
>
> Martin
