Re: [PATCH] vect: Move suggested_unroll_factor applying [PR105940]

["Kewen.Lin" <linkw@linux.ibm.com>]

on 2022/6/13 19:38, Richard Biener wrote:
> On Mon, Jun 13, 2022 at 12:02 PM Kewen.Lin <linkw@linux.ibm.com> wrote:
>>
>> Hi,
>>
>> As PR105940 shown, when rs6000 port tries to assign
>> m_suggested_unroll_factor by 4 or so, there will be ICE
>> on below statement:
>>
>>   exact_div (LOOP_VINFO_VECT_FACTOR (loop_vinfo),
>>              loop_vinfo->suggested_unroll_factor);
>>
>> In function vect_analyze_loop_2, the current place of
>> suggested_unroll_factor applying can't guarantee it's
>> applied for all cases.  As the case shows, vectorizer
>> could retry with SLP forced off, the vf is reset by
>> saved_vectorization_factor which isn't applied with
>> suggested_unroll_factor before.  It means it can end
>> up with one vf which neglects suggested_unroll_factor.
>> I think it's off design, we should move the applying
>> of suggested_unroll_factor after start_over.
>>
>> Bootstrapped and regtested on x86_64-redhat-linux,
>> aarch64-linux-gnu and powerpc64{,le}-linux-gnu.
>>
>> Is it ok for trunk?
> 
> OK (I think the GCC 12 branch is also affected).
> 

Thanks Richi!  Committed as r13-1083.

I'll backport this to GCC12 branch in a week if it goes well in trunk.

BR,
Kewen