On Thu, 18 Jul 2024, Jiawei wrote:
> This patch improves SLP reduction handling by ensuring proper processing
> even for a single reduction statement.Vectorization instances are now built
> only when there are multiple scalar statements to combine into an SLP
> reduction.
>
> An example see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110632,
> this patch fix this problem,handling SLP reduction as expected.
That PR is lacking any information so I'm not sure what kind of problem
you are fixing.
But the patch is clearly wrong - we want to use SLP even for single
reduction statements, the non-SLP path is going away.
Richard.
> gcc/ChangeLog:
>
> * tree-vect-slp.cc (vect_analyze_slp): Improved handling of SLP
> reductions
> for single reduction statements.
>
> ---
> gcc/tree-vect-slp.cc | 49 +++++++++++++++++++++-----------------------
> 1 file changed, 23 insertions(+), 26 deletions(-)
>
> diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
> index 55ae496cbb2..b6dfd9fd32f 100644
> --- a/gcc/tree-vect-slp.cc
> +++ b/gcc/tree-vect-slp.cc
> @@ -4054,34 +4054,31 @@ vect_analyze_slp (vec_info *vinfo, unsigned
> max_tree_size)
> }
> }
> /* Save for re-processing on failure. */
> - vec<stmt_vec_info> saved_stmts = scalar_stmts.copy ();
> - vec<stmt_vec_info> roots = vNULL;
> - vec<tree> remain = vNULL;
> - if (scalar_stmts.length () <= 1
> - || !vect_build_slp_instance (loop_vinfo,
> - slp_inst_kind_reduc_group,
> - scalar_stmts, roots, remain,
> - max_tree_size, &limit, bst_map,
> - NULL))
> - {
> - if (scalar_stmts.length () <= 1)
> - scalar_stmts.release ();
> - /* Do SLP discovery for single-lane reductions. */
> - for (auto stmt_info : saved_stmts)
> - {
> - vec<stmt_vec_info> stmts;
> - vec<stmt_vec_info> roots = vNULL;
> - vec<tree> remain = vNULL;
> - stmts.create (1);
> - stmts.quick_push (vect_stmt_to_vectorize (stmt_info));
> - vect_build_slp_instance (vinfo,
> - slp_inst_kind_reduc_group,
> - stmts, roots, remain,
> - max_tree_size, &limit,
> - bst_map, NULL);
> + if (loop_vinfo->reductions.length() > 0) {
> + vec<stmt_vec_info> scalar_stmts;
> + scalar_stmts.create(loop_vinfo->reductions.length());
> +
> + for (auto next_info : loop_vinfo->reductions) {
> + if (STMT_VINFO_DEF_TYPE(next_info) == vect_reduction_def) {
> + gassign *g = dyn_cast<gassign*>(STMT_VINFO_STMT(next_info));
> + if (!g || !lane_reducing_op_p(gimple_assign_rhs_code(g))) {
> + scalar_stmts.quick_push(next_info);
> }
> - saved_stmts.release ();
> + }
> }
> +
> + if (scalar_stmts.length() > 1) {
> + vec<stmt_vec_info> roots = vNULL;
> + vec<tree> remain = vNULL;
> + if (!vect_build_slp_instance(loop_vinfo, slp_inst_kind_reduc_group,
> scalar_stmts, roots, remain, max_tree_size, &limit, bst_map, NULL)) {
> + scalar_stmts.release();
> + }
> + }
> + else {
> + scalar_stmts.release();
> + }
> + }
> +
> }
> }
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
