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

[Yuri Rumyantsev <ysrumyan at gmail dot com>]

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;

Did you mean also that new combined patch must be working patch, i.e.
can be integrated without other patches?

Could you please look at updated patch?

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)

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