On Thu, Jul 8, 2021 at 2:46 PM Richard Sandiford via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> This patch passes the reduc_info to get_initial_defs_for_reduction,
> so that the function can get general information from there rather
> than from the first SLP statement. This isn't a win on its own,
> but it becomes important with later patches.
So the original code should have used SLP_TREE_REPRESENTATIVE
instead of SLP_TREE_SCALAR_STMTS ()[0] (there might have been
issues with doing that - my recollection is weak here).
I'm not sure if reduc_info is actually better - only the representative
will have STMT_VINFO_VECTYPE set, for the reduc_info
there's STMT_VINFO_REDUC_VECTYPE (and STMT_VINFO_REDUC_VECTYPE_IN).
So I think if you want to use reduc_info then you want to use
STMT_VINFO_REDUC_VECTYPE?
> gcc/
> * tree-vect-loop.c (get_initial_defs_for_reduction): Take the
> reduc_info as an additional parameter.
> (vect_transform_cycle_phi): Update accordingly.
> ---
> gcc/tree-vect-loop.c | 23 ++++++++++-------------
> 1 file changed, 10 insertions(+), 13 deletions(-)
>
> diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
> index a31d7621c3b..565c2859477 100644
> --- a/gcc/tree-vect-loop.c
> +++ b/gcc/tree-vect-loop.c
> @@ -4764,32 +4764,28 @@ get_initial_def_for_reduction (loop_vec_info
> loop_vinfo,
> return init_def;
> }
>
> -/* Get at the initial defs for the reduction PHIs in SLP_NODE.
> - NUMBER_OF_VECTORS is the number of vector defs to create.
> - If NEUTRAL_OP is nonnull, introducing extra elements of that
> - value will not change the result. */
> +/* Get at the initial defs for the reduction PHIs for REDUC_INFO, whose
> + associated SLP node is SLP_NODE. NUMBER_OF_VECTORS is the number of
> vector
> + defs to create. If NEUTRAL_OP is nonnull, introducing extra elements of
> + that value will not change the result. */
>
> static void
> get_initial_defs_for_reduction (vec_info *vinfo,
> + stmt_vec_info reduc_info,
> slp_tree slp_node,
> vec<tree> *vec_oprnds,
> unsigned int number_of_vectors,
> bool reduc_chain, tree neutral_op)
> {
> vec<stmt_vec_info> stmts = SLP_TREE_SCALAR_STMTS (slp_node);
> - stmt_vec_info stmt_vinfo = stmts[0];
> unsigned HOST_WIDE_INT nunits;
> unsigned j, number_of_places_left_in_vector;
> - tree vector_type;
> + tree vector_type = STMT_VINFO_VECTYPE (reduc_info);
> unsigned int group_size = stmts.length ();
> unsigned int i;
> class loop *loop;
>
> - vector_type = STMT_VINFO_VECTYPE (stmt_vinfo);
> -
> - gcc_assert (STMT_VINFO_DEF_TYPE (stmt_vinfo) == vect_reduction_def);
> -
> - loop = (gimple_bb (stmt_vinfo->stmt))->loop_father;
> + loop = (gimple_bb (reduc_info->stmt))->loop_father;
> gcc_assert (loop);
> edge pe = loop_preheader_edge (loop);
>
> @@ -4823,7 +4819,7 @@ get_initial_defs_for_reduction (vec_info *vinfo,
> {
> tree op;
> i = j % group_size;
> - stmt_vinfo = stmts[i];
> + stmt_vec_info stmt_vinfo = stmts[i];
>
> /* Get the def before the loop. In reduction chain we have only
> one initial value. Else we have as many as PHIs in the group. */
> @@ -7510,7 +7506,8 @@ vect_transform_cycle_phi (loop_vec_info loop_vinfo,
> = neutral_op_for_slp_reduction (slp_node, vectype_out,
> STMT_VINFO_REDUC_CODE
> (reduc_info),
> first != NULL);
> - get_initial_defs_for_reduction (loop_vinfo,
> slp_node_instance->reduc_phis,
> + get_initial_defs_for_reduction (loop_vinfo, reduc_info,
> + slp_node_instance->reduc_phis,
> &vec_initial_defs, vec_num,
> first != NULL, neutral_op);
> }
