Re: [PATCH] Pass correct type to irange::contains_p() in ipa-cp.cc.

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

On Mon, Apr 24, 2023 at 7:17 PM Aldy Hernandez <aldyh@redhat.com> wrote:
>
>
>
> On 4/24/23 14:35, Richard Biener wrote:
> > On Mon, Apr 24, 2023 at 2:32 PM Aldy Hernandez <aldyh@redhat.com> wrote:
> >>
> >>
> >>
> >> On 4/24/23 14:10, Richard Biener wrote:
> >>> On Mon, Apr 24, 2023 at 1:51 PM Aldy Hernandez <aldyh@redhat.com> wrote:
> >>>>
> >>>>
> >>>>
> >>>> On 4/24/23 10:30, Richard Biener wrote:
> >>>>> On Mon, Apr 24, 2023 at 9:44 AM Aldy Hernandez via Gcc-patches
> >>>>> <gcc-patches@gcc.gnu.org> wrote:
> >>>>>>
> >>>>>> There is a call to contains_p() in ipa-cp.cc which passes incompatible
> >>>>>> types.  This currently works because deep in the call chain, the legacy
> >>>>>> code uses tree_int_cst_lt which performs the operation with
> >>>>>> widest_int.  With the upcoming removal of legacy, contains_p() will be
> >>>>>> stricter.
> >>>>>>
> >>>>>> OK pending tests?
> >>>>>>
> >>>>>> gcc/ChangeLog:
> >>>>>>
> >>>>>>            * ipa-cp.cc (ipa_range_contains_p): New.
> >>>>>>            (decide_whether_version_node): Use it.
> >>>>>> ---
> >>>>>>     gcc/ipa-cp.cc | 16 +++++++++++++++-
> >>>>>>     1 file changed, 15 insertions(+), 1 deletion(-)
> >>>>>>
> >>>>>> diff --git a/gcc/ipa-cp.cc b/gcc/ipa-cp.cc
> >>>>>> index b3e0f62e400..c8013563796 100644
> >>>>>> --- a/gcc/ipa-cp.cc
> >>>>>> +++ b/gcc/ipa-cp.cc
> >>>>>> @@ -6180,6 +6180,19 @@ decide_about_value (struct cgraph_node *node, int index, HOST_WIDE_INT offset,
> >>>>>>       return true;
> >>>>>>     }
> >>>>>>
> >>>>>> +/* Like irange::contains_p(), but convert VAL to the range of R if
> >>>>>> +   necessary.  */
> >>>>>> +
> >>>>>> +static inline bool
> >>>>>> +ipa_range_contains_p (const irange &r, tree val)
> >>>>>> +{
> >>>>>> +  if (r.undefined_p ())
> >>>>>> +    return false;
> >>>>>> +
> >>>>>> +  val = fold_convert (r.type (), val);
> >>>>>
> >>>>> I think that's wrong, it might truncate 'val'.  I think we'd want
> >>>>>
> >>>>>       if (r.undefined_p () || !int_fits_type_p (val, r.type ()))
> >>>>>         return false;
> >>>>
> >>>> This won't work for pointers.  Is there a suitable version that handles
> >>>> pointers as well?
> >>>
> >>> Where does it not work?  And when do you get pointer values/types
> >>> where they mismatch sufficiently (how?) to make ranger unhappy?
> >>>
> >>
> >> It's not ranger that's unhappy, this is just irange::contains_p().
> >>
> >> IPA works on both integers and pointers, and pointers don't have
> >> TYPE_MIN/MAX_VALUE defined, so we ICE in int_fits_type_p:
> >>
> >>     type_low_bound = TYPE_MIN_VALUE (type);
> >>     type_high_bound = TYPE_MAX_VALUE (type);
> >
> > Ah.  The code handles NULL TYPE_MIN/MAX_VALUE just fine so
> > I wonder if it works to change the above to
> >
> >     type_low_bound = INTEGRAL_TYPE_P (type) ? TYPE_MIN_VALUE (type) : NULL_TREE;
> > ...
> >
> > alternatively you could use wi::fits_to_tree_p (wi::to_wide (val),
> > type) from the IPA code.
>
> That works.
>
> How's this?  Tested on x86-64 Linux.

LGTM.

> p.s. Once we convert the API to wide_int's (upcoming patches), I can
> move this logic into irange::contains_p (tree) virtual instead of
> ipa_range_contains_p.  We'll also have an irange::contains_p (const
> wide_int &) which we can upgrade to a widest_int overload if need be.