[PATCH PR95961] vect: ICE: in exact_div, at poly-int.h:2182

[Richard Sandiford]

"Yangfei (Felix)" <felix.yang@huawei.com> writes:
>> On June 30, 2020 4:23:03 PM GMT+02:00, Richard Sandiford
>> <richard.sandiford@arm.com> wrote:
>> >Richard Biener <rguenther@suse.de> writes:
>> >> So it seems odd to somehow put in the number of vectors...  so to me
>> >> it would have made sense if it did
>> >>
>> >>   possible_npeel_number = lower_bound (nscalars);
>> >>
>> >> or whateveris necessary to make the polys happy.  Thus simply elide
>> >> the vect_get_num_vectors call?  But it's been very long since I've
>> >> dived into the alignment peeling code...
>> >
>> >Ah, I see what you mean.  So rather than:
>> >
>> >	      /* Save info about DR in the hash table.  Also include peeling
>> >	         amounts according to the explanation above.  */
>> >              for (j = 0; j < possible_npeel_number; j++)
>> >                {
>> >                  vect_peeling_hash_insert (&peeling_htab, loop_vinfo,
>> >					    dr_info, npeel_tmp);
>> >		  npeel_tmp += target_align / dr_size;
>> >                }
>> >
>> >just have something like:
>> >
>> >	      while (known_le (npeel_tmp, nscalars))
>> >		{
>> >		  …
>> >		}
>> >
>> >?
>> 
>> Yeah.
>
> Not sure if I understand correctly.  I am supposing the following check in the original code is not necessary if we go like that.
>
> 1822               if (unlimited_cost_model (LOOP_VINFO_LOOP (loop_vinfo)))
>
> Is that correct?

I think we still need it.  I guess there are two choices:

- make nscalars default to npeel_tmp before the “if” above.
- put the loop inside the “if” and add a single call to
  vect_peeling_hash_insert as a new “else”.

Thanks,
Richard