Re: [r13-7135 Regression] FAIL: gcc.dg/vect/vect-simd-clone-18f.c scan-tree-dump-times vect "[\\n\\r] [^\\n]* = foo\\.simdclone" 2 on Linux/x86_64

["Andre Vieira (lists)" <andre.simoesdiasvieira@arm.com>]

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.simoesdiasvieira@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' ? 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).
 >
 >>
 >>> see vect_get_vector_types_for_stmt:
 >>> ...
 >>>     if (gimple_get_lhs (stmt) == NULL_TREE
 >>>         /* 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