On Mon, 10 Jan 2022, Andre Vieira (lists) wrote:
> Hi,
>
> I don't think I ever ended up posting the rebased version on top of the
> epilogue mode patch. So here it is, I think I had a conditional OK if I split
> the epilogue mode patch, but just want to double check this is OK for trunk?
Yes, I think I acked this.
Richard.
>
> gcc/ChangeLog:
>
> * tree-vect-loop.c (vect_estimate_min_profitable_iters): Pass new
> argument
> suggested_unroll_factor.
> (vect_analyze_loop_costing): Likewise.
> (_loop_vec_info::_loop_vec_info): Initialize new member
> suggested_unroll_factor.
> (vect_determine_partial_vectors_and_peeling): Make epilogue of
> unrolled
> main loop use partial vectors.
> (vect_analyze_loop_2): Pass and use new argument
> suggested_unroll_factor.
> (vect_analyze_loop_1): Likewise.
> (vect_analyze_loop): Change to intialize local
> suggested_unroll_factor and use it.
> (vectorizable_reduction): Don't use single_defuse_cycle when
> unrolling.
> * tree-vectorizer.h (_loop_vec_info::_loop_vec_info): Add new member
> suggested_unroll_factor.
> (vector_costs::vector_costs): Add new member
> m_suggested_unroll_factor.
> (vector_costs::suggested_unroll_factor): New getter function.
> (finish_cost): Set return argument suggested_unroll_factor.
>
>
>
> Regards,
> Andre
>
> On 30/11/2021 13:56, Richard Biener wrote:
> > On Tue, 30 Nov 2021, Andre Vieira (lists) wrote:
> >
> >> On 25/11/2021 12:46, Richard Biener wrote:
> >>> Oops, my fault, yes, it does. I would suggest to refactor things so
> >>> that the mode_i = first_loop_i case is there only once. I also wonder
> >>> if all the argument about starting at 0 doesn't apply to the
> >>> not unrolled LOOP_VINFO_EPIL_USING_PARTIAL_VECTORS_P as well? So
> >>> what's the reason to differ here? So in the end I'd just change
> >>> the existing
> >>>
> >>> if (LOOP_VINFO_EPIL_USING_PARTIAL_VECTORS_P (first_loop_vinfo))
> >>> {
> >>>
> >>> to
> >>>
> >>> if (LOOP_VINFO_EPIL_USING_PARTIAL_VECTORS_P (first_loop_vinfo)
> >>> || first_loop_vinfo->suggested_unroll_factor > 1)
> >>> {
> >>>
> >>> and maybe revisit this when we have an actual testcase showing that
> >>> doing sth else has a positive effect?
> >>>
> >>> Thanks,
> >>> Richard.
> >> So I had a quick chat with Richard Sandiford and he is suggesting resetting
> >> mode_i to 0 for all cases.
> >>
> >> He pointed out that for some tunings the SVE mode might come after the NEON
> >> mode, which means that even for not-unrolled loop_vinfos we could end up
> >> with
> >> a suboptimal choice of mode for the epilogue. I.e. it could be that we pick
> >> V16QI for main vectorization, but that's VNx16QI + 1 in the array, so we'd
> >> not
> >> try VNx16QI for the epilogue.
> >>
> >> This would simplify the mode selecting cases, by just simply restarting at
> >> mode_i in all epilogue cases. Is that something you'd be OK?
> > Works for me with an updated comment. Even better with showing a
> > testcase exercising such tuning.
> >
> > Richard.
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Ivo Totev; HRB 36809 (AG Nuernberg)
