Re: [PATCH, vec-tails] Support loop epilogue vectorization

[Richard Biener <rguenther at suse dot de>]

On November 14, 2016 4:39:40 PM GMT+01:00, Yuri Rumyantsev <ysrumyan@gmail.com> wrote:
>Richard,
>
>I checked one of the tests designed for epilogue vectorization using
>patches 1 - 3 and found out that build compiler performs vectorization
>of epilogues with --param vect-epilogues-nomask=1 passed:
>
>$ gcc -Ofast -mavx2 t1.c -S --param vect-epilogues-nomask=1 -o
>t1.new-nomask.s -fdump-tree-vect-details
>$ grep VECTORIZED -c t1.c.156t.vect
>4
> Without param only 2 loops are vectorized.
>
>Should I simply add a part of tests related to this feature or I must
>delete all not necessary changes also?

Please remove all not necessary changes.

Richard.

>Thanks.
>Yuri.
>
>2016-11-14 16:40 GMT+03:00 Richard Biener <rguenther@suse.de>:
>> On Mon, 14 Nov 2016, Yuri Rumyantsev wrote:
>>
>>> Richard,
>>>
>>> In my previous patch I forgot to remove couple lines related to aux
>field.
>>> Here is the correct updated patch.
>>
>> Yeah, I noticed.  This patch would be ok for trunk (together with
>> necessary parts from 1 and 2) if all not required parts are removed
>> (and you'd add the testcases covering non-masked tail vect).
>>
>> Thus, can you please produce a single complete patch containing only
>> non-masked epilogue vectoriziation?
>>
>> Thanks,
>> Richard.
>>
>>> Thanks.
>>> Yuri.
>>>
>>> 2016-11-14 15:51 GMT+03:00 Richard Biener <rguenther@suse.de>:
>>> > On Fri, 11 Nov 2016, Yuri Rumyantsev wrote:
>>> >
>>> >> Richard,
>>> >>
>>> >> I prepare updated 3 patch with passing additional argument to
>>> >> vect_analyze_loop as you proposed (untested).
>>> >>
>>> >> You wrote:
>>> >> tw, I wonder if you can produce a single patch containing just
>>> >> epilogue vectorization, that is combine patches 1-3 but rip out
>>> >> changes only needed by later patches?
>>> >>
>>> >> Did you mean that I exclude all support for vectorization
>epilogues,
>>> >> i.e. exclude from 2-nd patch all non-related changes
>>> >> like
>>> >>
>>> >> diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
>>> >> index 11863af..32011c1 100644
>>> >> --- a/gcc/tree-vect-loop.c
>>> >> +++ b/gcc/tree-vect-loop.c
>>> >> @@ -1120,6 +1120,12 @@ new_loop_vec_info (struct loop *loop)
>>> >>    LOOP_VINFO_PEELING_FOR_GAPS (res) = false;
>>> >>    LOOP_VINFO_PEELING_FOR_NITER (res) = false;
>>> >>    LOOP_VINFO_OPERANDS_SWAPPED (res) = false;
>>> >> +  LOOP_VINFO_CAN_BE_MASKED (res) = false;
>>> >> +  LOOP_VINFO_REQUIRED_MASKS (res) = 0;
>>> >> +  LOOP_VINFO_COMBINE_EPILOGUE (res) = false;
>>> >> +  LOOP_VINFO_MASK_EPILOGUE (res) = false;
>>> >> +  LOOP_VINFO_NEED_MASKING (res) = false;
>>> >> +  LOOP_VINFO_ORIG_LOOP_INFO (res) = NULL;
>>> >
>>> > Yes.
>>> >
>>> >> Did you mean also that new combined patch must be working patch,
>i.e.
>>> >> can be integrated without other patches?
>>> >
>>> > Yes.
>>> >
>>> >> Could you please look at updated patch?
>>> >
>>> > Will do.
>>> >
>>> > Thanks,
>>> > Richard.
>>> >
>>> >> Thanks.
>>> >> Yuri.
>>> >>
>>> >> 2016-11-10 15:36 GMT+03:00 Richard Biener <rguenther@suse.de>:
>>> >> > On Thu, 10 Nov 2016, Richard Biener wrote:
>>> >> >
>>> >> >> On Tue, 8 Nov 2016, Yuri Rumyantsev wrote:
>>> >> >>
>>> >> >> > Richard,
>>> >> >> >
>>> >> >> > Here is updated 3 patch.
>>> >> >> >
>>> >> >> > I checked that all new tests related to epilogue
>vectorization passed with it.
>>> >> >> >
>>> >> >> > Your comments will be appreciated.
>>> >> >>
>>> >> >> A lot better now.  Instead of the ->aux dance I now prefer to
>>> >> >> pass the original loops loop_vinfo to vect_analyze_loop as
>>> >> >> optional argument (if non-NULL we analyze the epilogue of that
>>> >> >> loop_vinfo).  OTOH I remember we mainly use it to get at the
>>> >> >> original vectorization factor?  So we can pass down an
>(optional)
>>> >> >> forced vectorization factor as well?
>>> >> >
>>> >> > Btw, I wonder if you can produce a single patch containing just
>>> >> > epilogue vectorization, that is combine patches 1-3 but rip out
>>> >> > changes only needed by later patches?
>>> >> >
>>> >> > Thanks,
>>> >> > Richard.
>>> >> >
>>> >> >> Richard.
>>> >> >>
>>> >> >> > 2016-11-08 15:38 GMT+03:00 Richard Biener
><rguenther@suse.de>:
>>> >> >> > > On Thu, 3 Nov 2016, Yuri Rumyantsev wrote:
>>> >> >> > >
>>> >> >> > >> Hi Richard,
>>> >> >> > >>
>>> >> >> > >> I did not understand your last remark:
>>> >> >> > >>
>>> >> >> > >> > That is, here (and avoid the FOR_EACH_LOOP change):
>>> >> >> > >> >
>>> >> >> > >> > @@ -580,12 +586,21 @@ vectorize_loops (void)
>>> >> >> > >> >           && dump_enabled_p ())
>>> >> >> > >> >           dump_printf_loc (MSG_OPTIMIZED_LOCATIONS,
>vect_location,
>>> >> >> > >> >                            "loop vectorized\n");
>>> >> >> > >> > -       vect_transform_loop (loop_vinfo);
>>> >> >> > >> > +       new_loop = vect_transform_loop (loop_vinfo);
>>> >> >> > >> >         num_vectorized_loops++;
>>> >> >> > >> >        /* Now that the loop has been vectorized, allow
>it to be unrolled
>>> >> >> > >> >           etc.  */
>>> >> >> > >> >      loop->force_vectorize = false;
>>> >> >> > >> >
>>> >> >> > >> > +       /* Add new loop to a processing queue.  To make
>it easier
>>> >> >> > >> > +          to match loop and its epilogue vectorization
>in dumps
>>> >> >> > >> > +          put new loop as the next loop to process. 
>*/
>>> >> >> > >> > +       if (new_loop)
>>> >> >> > >> > +         {
>>> >> >> > >> > +           loops.safe_insert (i + 1, new_loop->num);
>>> >> >> > >> > +           vect_loops_num = number_of_loops (cfun);
>>> >> >> > >> > +         }
>>> >> >> > >> >
>>> >> >> > >> > simply dispatch to a vectorize_epilogue (loop_vinfo,
>new_loop)
>>> >> >> > >> f> unction which will set up stuff properly (and also
>perform
>>> >> >> > >> > the if-conversion of the epilogue there).
>>> >> >> > >> >
>>> >> >> > >> > That said, if we can get in non-masked epilogue
>vectorization
>>> >> >> > >> > separately that would be great.
>>> >> >> > >>
>>> >> >> > >> Could you please clarify your proposal.
>>> >> >> > >
>>> >> >> > > When a loop was vectorized set things up to immediately
>vectorize
>>> >> >> > > its epilogue, avoiding changing the loop iteration and
>avoiding
>>> >> >> > > the re-use of ->aux.
>>> >> >> > >
>>> >> >> > > Richard.
>>> >> >> > >
>>> >> >> > >> Thanks.
>>> >> >> > >> Yuri.
>>> >> >> > >>
>>> >> >> > >> 2016-11-02 15:27 GMT+03:00 Richard Biener
><rguenther@suse.de>:
>>> >> >> > >> > On Tue, 1 Nov 2016, Yuri Rumyantsev wrote:
>>> >> >> > >> >
>>> >> >> > >> >> Hi All,
>>> >> >> > >> >>
>>> >> >> > >> >> I re-send all patches sent by Ilya earlier for review
>which support
>>> >> >> > >> >> vectorization of loop epilogues and loops with low
>trip count. We
>>> >> >> > >> >> assume that the only patch -
>vec-tails-07-combine-tail.patch - was not
>>> >> >> > >> >> approved by Jeff.
>>> >> >> > >> >>
>>> >> >> > >> >> I did re-base of all patches and performed
>bootstrapping and
>>> >> >> > >> >> regression testing that did not show any new failures.
>Also all
>>> >> >> > >> >> changes related to new vect_do_peeling algorithm have
>been changed
>>> >> >> > >> >> accordingly.
>>> >> >> > >> >>
>>> >> >> > >> >> Is it OK for trunk?
>>> >> >> > >> >
>>> >> >> > >> > I would have prefered that the series up to
>-03-nomask-tails would
>>> >> >> > >> > _only_ contain epilogue loop vectorization changes but
>unfortunately
>>> >> >> > >> > the patchset is oddly separated.
>>> >> >> > >> >
>>> >> >> > >> > I have a comment on that part nevertheless:
>>> >> >> > >> >
>>> >> >> > >> > @@ -1608,7 +1614,10 @@ vect_enhance_data_refs_alignment
>(loop_vec_info
>>> >> >> > >> > loop_vinfo)
>>> >> >> > >> >    /* Check if we can possibly peel the loop.  */
>>> >> >> > >> >    if (!vect_can_advance_ivs_p (loop_vinfo)
>>> >> >> > >> >        || !slpeel_can_duplicate_loop_p (loop,
>single_exit (loop))
>>> >> >> > >> > -      || loop->inner)
>>> >> >> > >> > +      || loop->inner
>>> >> >> > >> > +      /* Required peeling was performed in prologue
>and
>>> >> >> > >> > +        is not required for epilogue.  */
>>> >> >> > >> > +      || LOOP_VINFO_EPILOGUE_P (loop_vinfo))
>>> >> >> > >> >      do_peeling = false;
>>> >> >> > >> >
>>> >> >> > >> >    if (do_peeling
>>> >> >> > >> > @@ -1888,7 +1897,10 @@ vect_enhance_data_refs_alignment
>(loop_vec_info
>>> >> >> > >> > loop_vinfo)
>>> >> >> > >> >
>>> >> >> > >> >    do_versioning =
>>> >> >> > >> >         optimize_loop_nest_for_speed_p (loop)
>>> >> >> > >> > -       && (!loop->inner); /* FORNOW */
>>> >> >> > >> > +       && (!loop->inner) /* FORNOW */
>>> >> >> > >> > +        /* Required versioning was performed for the
>>> >> >> > >> > +          original loop and is not required for
>epilogue.  */
>>> >> >> > >> > +       && !LOOP_VINFO_EPILOGUE_P (loop_vinfo);
>>> >> >> > >> >
>>> >> >> > >> >    if (do_versioning)
>>> >> >> > >> >      {
>>> >> >> > >> >
>>> >> >> > >> > please do that check in the single caller of this
>function.
>>> >> >> > >> >
>>> >> >> > >> > Otherwise I still dislike the new ->aux use and I
>believe that simply
>>> >> >> > >> > passing down info from the processed parent would be
>_much_ cleaner.
>>> >> >> > >> > That is, here (and avoid the FOR_EACH_LOOP change):
>>> >> >> > >> >
>>> >> >> > >> > @@ -580,12 +586,21 @@ vectorize_loops (void)
>>> >> >> > >> >             && dump_enabled_p ())
>>> >> >> > >> >            dump_printf_loc (MSG_OPTIMIZED_LOCATIONS,
>vect_location,
>>> >> >> > >> >                             "loop vectorized\n");
>>> >> >> > >> > -       vect_transform_loop (loop_vinfo);
>>> >> >> > >> > +       new_loop = vect_transform_loop (loop_vinfo);
>>> >> >> > >> >         num_vectorized_loops++;
>>> >> >> > >> >         /* Now that the loop has been vectorized, allow
>it to be unrolled
>>> >> >> > >> >            etc.  */
>>> >> >> > >> >         loop->force_vectorize = false;
>>> >> >> > >> >
>>> >> >> > >> > +       /* Add new loop to a processing queue.  To make
>it easier
>>> >> >> > >> > +          to match loop and its epilogue vectorization
>in dumps
>>> >> >> > >> > +          put new loop as the next loop to process. 
>*/
>>> >> >> > >> > +       if (new_loop)
>>> >> >> > >> > +         {
>>> >> >> > >> > +           loops.safe_insert (i + 1, new_loop->num);
>>> >> >> > >> > +           vect_loops_num = number_of_loops (cfun);
>>> >> >> > >> > +         }
>>> >> >> > >> >
>>> >> >> > >> > simply dispatch to a vectorize_epilogue (loop_vinfo,
>new_loop)
>>> >> >> > >> > function which will set up stuff properly (and also
>perform
>>> >> >> > >> > the if-conversion of the epilogue there).
>>> >> >> > >> >
>>> >> >> > >> > That said, if we can get in non-masked epilogue
>vectorization
>>> >> >> > >> > separately that would be great.
>>> >> >> > >> >
>>> >> >> > >> > I'm still torn about all the rest of the stuff and
>question its
>>> >> >> > >> > usability (esp. merging the epilogue with the main
>vector loop).
>>> >> >> > >> > But it has already been approved ... oh well.
>>> >> >> > >> >
>>> >> >> > >> > Thanks,
>>> >> >> > >> > Richard.
>>> >> >> > >>
>>> >> >> > >>
>>> >> >> > >
>>> >> >> > > --
>>> >> >> > > Richard Biener <rguenther@suse.de>
>>> >> >> > > SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard,
>Graham Norton, HRB 21284 (AG Nuernberg)
>>> >> >> >
>>> >> >>
>>> >> >>
>>> >> >
>>> >> > --
>>> >> > Richard Biener <rguenther@suse.de>
>>> >> > SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham
>Norton, HRB 21284 (AG Nuernberg)
>>> >>
>>> >
>>> > --
>>> > Richard Biener <rguenther@suse.de>
>>> > SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham
>Norton, HRB 21284 (AG Nuernberg)
>>>
>>
>> --
>> Richard Biener <rguenther@suse.de>
>> SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham
>Norton, HRB 21284 (AG Nuernberg)