Re: [PATCH 1/2]middle-end: Fix wrong overmatching of div-bitmask by using new optabs [PR108583]

[Andrew MacLeod <amacleod@redhat.com>]

On 2/22/23 13:03, Tamar Christina wrote:
>> -----Original Message-----
>> From: Andrew MacLeod <amacleod@redhat.com>
>> Sent: Wednesday, February 22, 2023 4:42 PM
>> To: Tamar Christina <Tamar.Christina@arm.com>; Richard Biener
>> <rguenther@suse.de>; Richard Sandiford <Richard.Sandiford@arm.com>
>> Cc: Tamar Christina via Gcc-patches <gcc-patches@gcc.gnu.org>; nd
>> <nd@arm.com>; jlaw@ventanamicro.com
>> Subject: Re: [PATCH 1/2]middle-end: Fix wrong overmatching of div-bitmask
>> by using new optabs [PR108583]
>>
>>
>> On 2/15/23 13:42, Andrew MacLeod wrote:
>>> On 2/15/23 12:50, Andrew MacLeod wrote:
>>>> On 2/15/23 12:13, Tamar Christina wrote:
>>>>>> On 2/15/23 07:51, Tamar Christina wrote:
>>>> void
>>>> operator_plus::wi_fold (irange &r, tree type,
>>>>                          const wide_int &lh_lb, const wide_int &lh_ub,
>>>>                          const wide_int &rh_lb, const wide_int &rh_ub)
>>>> const {
>>>>    wi::overflow_type ov_lb, ov_ub;
>>>>    signop s = TYPE_SIGN (type);
>>>>
>>>>    // Do whatever wideint magic is required to do this adds in higher
>>>> precision
>>>>    wide_int new_lb = wi::add (lh_lb, rh_lb, s, &ov_lb);
>>>>    wide_int new_ub = wi::add (lh_ub, rh_ub, s, &ov_ub);
>>>>
>>>>    r = int_range<2> (type, new_lb, new_ub); }
>>>>
>>>>
>>>> The operator needs to be registered, I've attached the skeleton for
>>>> it.  you should just have to finish implementing wi_fold().
>>>>
>>>> in theory :-)
>>>>
>>> You also mentioned earlier that some were tree codes, some were
>>> internal function calls?  We have some initial support for built in
>>> functions, but I am not familiar with all the various forms they can
>>> take.  We currently support CFN_ functions in
>>>
>>>    gimple-range-op.cc, gimple_range_op_handler::maybe_builtin_call ()
>>>
>>> Basically this is part of a "gimple_range_op_handler"  wrapper for
>>> range-ops which can provide a range-ops class for stmts that don't map
>>> to a binary or unary form.. such as built in functions.
>>>
>>> If you get to the point where you need this for a builtin function, I
>>> can help you through that too.  Although someone may have to also help
>>> me through what differentiates the different kinds of internal
>>> function :-)    I presume they are all similar in some way.
>>>
>>> Andrew
>>>
>> Oh yeah, and in case you haven't figured it out on your own, you'll have
>> to remove WIDEN_MULT_EXPR from the range-ops init table.   This
>> non-standard mechanism only gets checked if there is no standard
>> range-op table entry for the tree code :-P
>>
> Hmm it looks like it'll work, but it keeps segfaulting in:
>
> bool
> range_op_handler::fold_range (vrange &r, tree type,
> 			      const vrange &lh,
> 			      const vrange &rh,
> 			      relation_trio rel) const
> {
>    gcc_checking_assert (m_valid);
>    if (m_int)
>      return m_int->fold_range (as_a <irange> (r), type,
> 			   as_a <irange> (lh),
> 			   as_a <irange> (rh), rel);
>
> while trying to call fold_range.
>
> But m_int is set to the right instance. Probably something I'm missing,
> I'll double check it all.
>
Hmm.  whats your class operator_widen_mult* look like? what are you 
inheriting from?   Send me your patch and I'll have a look if you want.  
this is somewhat  new territory :-)

I cant imagine it being a linkage thing between the 2 files since the 
operator is defined in another file and the address taken in this one? 
that should work, but strange that cant make the call...

Andrew