On Fri, Apr 14, 2023 at 10:43 AM Andre Vieira (lists)
<andre.simoesdiasvie...@arm.com> wrote:
>
> Resending this to everyone (sorry for the double send Richard).
>
> On 14/04/2023 09:15, Andre Vieira (lists) wrote:
> >
> >
> > On 14/04/2023 07:55, Richard Biener wrote:
> >> On Thu, Apr 13, 2023 at 4:25 PM Andre Vieira (lists)
> >> <andre.simoesdiasvie...@arm.com> wrote:
> >>>
> >>>
> >>>
> >>> On 13/04/2023 15:00, Richard Biener wrote:
> >>>> On Thu, Apr 13, 2023 at 3:00 PM Andre Vieira (lists) via Gcc-patches
> >>>> <gcc-patches@gcc.gnu.org> wrote:
> >>>>>
> >>>>>
> >>>>>
> >>>
> >>> But that's not it, I've been looking at it, and there is code in place
> >>> that does what I expected which is defer the choice of vectype for simd
> >>> clones until vectorizable_simd_clone_call, unfortunately it has a
> >>> mistaken assumption that simdclones don't return :/
> >>
> >> I think that's not it - when the SIMD clone returns a vector we have to
> >> determine the vector type in this function. We cannot defer this.
> >
> > What's 'this function' here, do you mean we have to determine the
> > vectype in 'vect_get_vector_types_for_stmt' &
> > 'vect_determine_vf_for_stmt' ?
Yes.
> Because at that time we don't yet know
> > what clone we will be using, this choice is done inside
> > vectorizable_simd_clone_call. In fact, to choose the simd clone, we need
> > to know the vf as that has to be a multiple of the chosen clone's
> > simdlen. So we simply can't use the simdclone's types (as that depends
> > on the simdlen) to choose the vf because the choice of simdlend depends
> > on the vf. And there was already code in place to handle this,
> > unfortunately that code was wrong and had the wrong assumption that
> > simdclones didn't return (probably was true at some point and bitrotted).
But to compute the VF we need to know the vector types! We're only
calling vectorizable_* when the VF is final. That said, the code you quote:
> >>
> >>> see vect_get_vector_types_for_stmt:
> >>> ...
> >>> if (gimple_get_lhs (stmt) == NULL_TREE
is just for the case of a function without return value. For this case
it's OK to do nothing - 'vectype' is the vector type of all vector defs
a stmt produces.
For calls with a LHS it should fall through to generic code doing
get_vectype_for_scalar_type on the LHS type.
> >>> /* MASK_STORE has no lhs, but is ok. */
> >>> && !gimple_call_internal_p (stmt, IFN_MASK_STORE))
> >>> {
> >>> if (is_a <gcall *> (stmt))
> >>> {
> >>> /* Ignore calls with no lhs. These must be calls to
> >>> #pragma omp simd functions, and what vectorization
> factor
> >>> it really needs can't be determined until
> >>> vectorizable_simd_clone_call. */
> >>> if (dump_enabled_p ())
> >>> dump_printf_loc (MSG_NOTE, vect_location,
> >>> "defer to SIMD clone analysis.\n");
> >>> return opt_result::success ();
> >>> }
> >>>
> >>> return opt_result::failure_at (stmt,
> >>> "not vectorized: irregular
> >>> stmt.%G", stmt);
> >>> }
> >>> ...
> >>>
> >>> I'm working on a patch.
> >>>>
> >>>>> Kind Regards,
> >>>>> Andre
