BTW, I'm not opposed to this patch. Thank you for tracking this down,
and feel free to commit as is if y'all PMs agree it's OK. I just
wanted to know if there's a better way going forward. I can certainly
put it on my TODO list once stage1 opens again.
And no, there probably isn't an obstack for those classes, but I
wonder if we should have a class local one, as we do for the rest of
the classes.
Aldy
On Mon, Apr 8, 2024 at 7:47 PM Richard Biener
<richard.guent...@gmail.com> wrote:
>
>
>
> > Am 08.04.2024 um 18:40 schrieb Aldy Hernandez <al...@redhat.com>:
> >
> > On Mon, Apr 8, 2024 at 6:29 PM Richard Biener <rguent...@suse.de> wrote:
> >>
> >>
> >>
> >>>> Am 08.04.2024 um 18:09 schrieb Aldy Hernandez <al...@redhat.com>:
> >>>
> >>> On Mon, Apr 8, 2024 at 5:54 PM Jakub Jelinek <ja...@redhat.com> wrote:
> >>>>
> >>>> On Mon, Apr 08, 2024 at 05:40:23PM +0200, Aldy Hernandez wrote:
> >>>>>> PR middle-end/114604
> >>>>>> * gimple-range.cc (enable_ranger): Initialize the global
> >>>>>> bitmap obstack.
> >>>>>> (disable_ranger): Release it.
> >>>>>> ---
> >>>>>> gcc/gimple-range.cc | 4 ++++
> >>>>>> 1 file changed, 4 insertions(+)
> >>>>>>
> >>>>>> diff --git a/gcc/gimple-range.cc b/gcc/gimple-range.cc
> >>>>>> index c16b776c1e3..4d3b1ce8588 100644
> >>>>>> --- a/gcc/gimple-range.cc
> >>>>>> +++ b/gcc/gimple-range.cc
> >>>>>> @@ -689,6 +689,8 @@ enable_ranger (struct function *fun, bool
> >>>>>> use_imm_uses)
> >>>>>> {
> >>>>>> gimple_ranger *r;
> >>>>>>
> >>>>>> + bitmap_obstack_initialize (NULL);
> >>>>>> +
> >>>>>> gcc_checking_assert (!fun->x_range_query);
> >>>>>> r = new gimple_ranger (use_imm_uses);
> >>>>>> fun->x_range_query = r;
> >>>>>> @@ -705,6 +707,8 @@ disable_ranger (struct function *fun)
> >>>>>> gcc_checking_assert (fun->x_range_query);
> >>>>>> delete fun->x_range_query;
> >>>>>> fun->x_range_query = NULL;
> >>>>>> +
> >>>>>> + bitmap_obstack_release (NULL);
> >>>>>
> >>>>> Are you not allowed to initialize/use obstacks unless
> >>>>> bitmap_obstack_initialize(NULL) is called?
> >>>>
> >>>> You can use it with some other obstack, just not the default one.
> >>>>
> >>>>> If so, wouldn't it be
> >>>>> better to lazily initialize it downstream (bitmap_alloc, or whomever
> >>>>> needs it initialized)?
> >>>>
> >>>> No, you still need to decide where is the safe point to release it.
> >>>> Unlike the non-default bitmap_obstack_initialize/bitmap_obstack_release,
> >>>> the default one can nest (has associated nesting counter). So, the above
> >>>> patch just says that ranger starts using the default obstack in
> >>>> enable_ranger and stops using it in disable_ranger and anything ranger
> >>>> associated in the obstack can be freed at that point.
> >>>
> >>> I thought ranger never used the default one:
> >>>
> >>> $ grep bitmap_obstack_initialize *value* *range*
> >>> value-relation.cc: bitmap_obstack_initialize (&m_bitmaps);
> >>> value-relation.cc: bitmap_obstack_initialize (&m_bitmaps);
> >>> gimple-range-cache.cc: bitmap_obstack_initialize (&m_bitmaps);
> >>> gimple-range-gori.cc: bitmap_obstack_initialize (&m_bitmaps);
> >>> gimple-range-infer.cc: bitmap_obstack_initialize (&m_bitmaps);
> >>> gimple-range-phi.cc: bitmap_obstack_initialize (&m_bitmaps);
> >>>
> >>> or even:
> >>>
> >>> $ grep obstack.*NULL *value* *range*
> >>> value-range-storage.cc: obstack_free (&m_obstack, NULL);
> >>> value-relation.cc: obstack_free (&m_chain_obstack, NULL);
> >>> value-relation.cc: obstack_free (&m_chain_obstack, NULL);
> >>> gimple-range-infer.cc: obstack_free (&m_list_obstack, NULL);
> >>> value-range-storage.cc: obstack_free (&m_obstack, NULL);
> >>>
> >>> I'm obviously missing something here.
> >>
> >> Look for BITMAP_ALLOC (NULL) in the backtrace in the PR
> >
> > Ahh! Thanks.
> >
> > A few default obstack uses snuck in while I wasn't looking.
> >
> > $ grep BITMAP_ALLOC.*NULL *range*
> > gimple-range-cache.cc: m_propfail = BITMAP_ALLOC (NULL);
> > gimple-range-cache.h: inline ssa_lazy_cache () { active_p =
> > BITMAP_ALLOC (NULL); }
> > gimple-range.cc: m_pop_list = BITMAP_ALLOC (NULL);
> >
> > I wonder if it would be cleaner to just change these to use named obstacks.
>
> I didn’t find any obvious obstack to use, but sure. This was the easiest fix
> ;)
>
> Richard
>
> > Andrew, is there a reason we were using the default obstack for these?
> > For reference, they are class update_list used in the ranger cache,
> > ssa_lazy_cache, and dom_ranger.
> >
> > Aldy
> >
>
