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.
Aldy
