On Thu, Jul 24, 2025 at 2:20 PM Alfie Richards <alfie.richa...@arm.com> wrote:
>
> Hi,
>
> This patch comes from me getting confused about gimple dumps from vect.
> Specifically, while seemingly not causing any issues I found the conversion of
> the IV step from an integral step, to a pointer value, and then to sizetype
> misleading. By the look of things create_iv already has the infrastructure to
> support a pointer type base with integral mode step, so this seemed a nice
> clean up?
>
> In conversation with Richard S offline he suggested this may be like this
> as PLUS_EXPR requires match argument type, but seemingly we have dropped that
> requirement for create_iv as I think the use at gcc/tree-vect-stmts.cc:8683
> has non-matching types?
I think this simply pre-dates POINTER_PLUS_EXPR support and create_iv
transparently uses than when passed PLUS_EXPR.
>
> Thoughts? Is it worth changing the code argument of create_iv to an UP/DOWN
> enum instead if this is the intended use case?
I'm not sure, PLUS_EXPR/MINUS_EXPR is good enough IMO.
>
> Bootstrapped and reg-tested on aarch64 and x86_64.
OK.
Richard.
> Thanks,
> Alfie
>
> -- >8 --
>
> Removes `fold_convert (aggr_ptr_type, STEP)` when using create_iv.
>
> This was previously constructing statements like:
> ```
> unsigned int _49;
> vector([4,4]) int * _50;
> sizetype _51;
> vector([4,4]) int * vectp_x.6;
> ...
> _50 = (vector([4,4]) int *) _49;
> _51 = (sizetype) _50;
> ...
> vectp_x.6_48 = vectp_x.6_47 + _51;
> ```
>
> And instead creates:
> ```
> unsigned int _49;
> sizetype _50;
> vector([4,4]) int * vectp_x.6;
> ...
> _50 = (sizetype) _49;
> ...
> vectp_x.6_48 = vectp_x.6_47 + _50;
> ```
>
> As create_iv already has the logic to handle a pointer mode base and an
> integer
> mode var this seems a more natural expression of this.
>
> gcc/ChangeLog:
>
> * tree-vect-data-refs.cc (vect_create_data_ref_ptr):
> ---
> gcc/tree-vect-data-refs.cc | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/gcc/tree-vect-data-refs.cc b/gcc/tree-vect-data-refs.cc
> index 460a48db2e6..5f672132a8a 100644
> --- a/gcc/tree-vect-data-refs.cc
> +++ b/gcc/tree-vect-data-refs.cc
> @@ -5718,8 +5718,7 @@ vect_create_data_ref_ptr (vec_info *vinfo,
> stmt_vec_info stmt_info,
> standard_iv_increment_position (loop, &incr_gsi, &insert_after);
>
> create_iv (aggr_ptr_init, PLUS_EXPR,
> - fold_convert (aggr_ptr_type, iv_step),
> - aggr_ptr, loop, &incr_gsi, insert_after,
> + iv_step, aggr_ptr, loop, &incr_gsi, insert_after,
> &indx_before_incr, &indx_after_incr);
> incr = gsi_stmt (incr_gsi);
>
> @@ -5747,7 +5746,7 @@ vect_create_data_ref_ptr (vec_info *vinfo,
> stmt_vec_info stmt_info,
> {
> standard_iv_increment_position (containing_loop, &incr_gsi,
> &insert_after);
> - create_iv (aptr, PLUS_EXPR, fold_convert (aggr_ptr_type, DR_STEP (dr)),
> + create_iv (aptr, PLUS_EXPR, DR_STEP (dr),
> aggr_ptr, containing_loop, &incr_gsi, insert_after,
> &indx_before_incr, &indx_after_incr);
> incr = gsi_stmt (incr_gsi);
> --
> 2.34.1
>
