Re: [PATCH] Enable auto-vectorization at O2 with very-cheap cost model.

[Richard Biener <richard.guenther@gmail.com>]

On Mon, Sep 6, 2021 at 2:30 PM Jakub Jelinek <jakub@redhat.com> wrote:
>
> On Mon, Sep 06, 2021 at 02:18:59PM +0200, Richard Biener wrote:
> > On Mon, Sep 6, 2021 at 1:15 PM Jakub Jelinek <jakub@redhat.com> wrote:
> > >
> > > On Mon, Sep 06, 2021 at 07:15:41PM +0800, Hongtao Liu wrote:
> > > > > So what about finish_options then?
> > > > > default_options_optimization has only a single caller that then calls
> > > > > read_cmdline_options and then finish_options.
> > > > in finish_options
> > > > (gdb) p opts_set->x_flag_tree_loop_vectorize
> > > > $37 = 1
> > > > with -O2 -ftree-loop-vectorize,
> > > >
> > > > but
> > > > 1000   if (opts->x_dump_base_name
> > > > (gdb) p opts_set->x_flag_tree_loop_vectorize
> > > > $38 = 0
> > > > for -O2 -ftree-vectorize???
> > > >
> > > > Any magic  for ftree-vectorize w/ EnabledBy???
> > >
> > > I guess a way to get this working would be:
> > >  ; Alias to enable both -ftree-loop-vectorize and -ftree-slp-vectorize.
> > >  ftree-vectorize
> > > -Common Optimization
> > > +Common Var(flag_tree_vectorize) Optimization
> > >  Enable vectorization on trees.
> > >
> > > and then you can test both
> > > opts_set->x_flag_tree_vectorize
> > > and
> > > opts_set->x_flag_tree_loop_vectorize
> >
> > Or make EnabledBy have set opts_set-> as well.
>
> That would change a little bit what *_set->x_* means.
>
> If user has explicit -O2, we have *_set->x_optimize set,
> but don't enable it on all the suboptions that are implicitly
> enabled because explicit -O2 has been used.
> And isn't EnabledBy practically the same?  If user writes
> -Wall explicitly which implicitly enables hundreds of warning
> options, do we want just Wall or also all the other options
> marked as explicit?  E.g. backend code than can't easily differentiate
> between -Wwhatever and -Wall implying -Wwhatever and e.g. changing that
> if implicit only.

Hmm, good point.

Richard.

>
>         Jakub
>