On Tue, 14 Nov 2023, Tamar Christina wrote:
> > > OK, but then I think the fix is to not use
> > > standard_iv_increment_position (it's a weird API anyway). Instead insert
> > before the main exit condition.
> >
> > I figured as much, Almost done respinning it with the vectorizer's own
> > simpler
> > copy.
> > Should be out today with the rest.
> >
> > >
> > > Btw, I assumed this order of main / early exit cannot happen. But I
> > > didn't re- review the main exit identification code yet.
> > >
> >
> > It can happen because we allowed vec_init_loop_exit_info to pick the last
> > analyzable exit. In cases like these it happens because the final exit has
> > no
> > Information from SCEV. It then picks the last exit it could analyze which by
> > default is an early exit.
> >
> > It's very tricky to deal with and have just finished cleaning up the IV
> > update
> > code to make it easier to follow... but it does seem to add about 970 more
> > vectorized cases (most of which are execution tests).
> >
>
> Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
>
> Ok for master?
OK.
Richard.
> Thanks,
> Tamar
>
> gcc/ChangeLog:
>
> * tree-vect-loop-manip.cc (vect_iv_increment_position): New.
> (vect_set_loop_controls_directly): Use it.
> (vect_set_loop_condition_partial_vectors_avx512): Likewise.
> (vect_set_loop_condition_normal): Likewise.
>
> --- inline copy of patch ---
>
> diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
> index
> fafbf924e8db18eb4eec7a4a1906d10f6ce9812f..a5a612dc6b47436730592469176623685a7a413f
> 100644
> --- a/gcc/tree-vect-loop-manip.cc
> +++ b/gcc/tree-vect-loop-manip.cc
> @@ -448,6 +448,20 @@ vect_adjust_loop_lens_control (tree iv_type, gimple_seq
> *seq,
> }
> }
>
> +/* Stores the standard position for induction variable increment in
> belonging to
> + LOOP_EXIT (just before the exit condition of the given exit to BSI.
> + INSERT_AFTER is set to true if the increment should be inserted after
> + *BSI. */
> +
> +static void
> +vect_iv_increment_position (edge loop_exit, gimple_stmt_iterator *bsi,
> + bool *insert_after)
> +{
> + basic_block bb = loop_exit->src;
> + *bsi = gsi_last_bb (bb);
> + *insert_after = false;
> +}
> +
> /* Helper for vect_set_loop_condition_partial_vectors. Generate definitions
> for all the rgroup controls in RGC and return a control that is nonzero
> when the loop needs to iterate. Add any new preheader statements to
> @@ -531,7 +545,8 @@ vect_set_loop_controls_directly (class loop *loop,
> loop_vec_info loop_vinfo,
> tree index_before_incr, index_after_incr;
> gimple_stmt_iterator incr_gsi;
> bool insert_after;
> - standard_iv_increment_position (loop, &incr_gsi, &insert_after);
> + edge exit_e = LOOP_VINFO_IV_EXIT (loop_vinfo);
> + vect_iv_increment_position (exit_e, &incr_gsi, &insert_after);
> if (LOOP_VINFO_USING_DECREMENTING_IV_P (loop_vinfo))
> {
> /* Create an IV that counts down from niters_total and whose step
> @@ -1017,7 +1032,7 @@ vect_set_loop_condition_partial_vectors_avx512 (class
> loop *loop,
> tree index_before_incr, index_after_incr;
> gimple_stmt_iterator incr_gsi;
> bool insert_after;
> - standard_iv_increment_position (loop, &incr_gsi, &insert_after);
> + vect_iv_increment_position (exit_edge, &incr_gsi, &insert_after);
> create_iv (niters_adj, MINUS_EXPR, iv_step, NULL_TREE, loop,
> &incr_gsi, insert_after, &index_before_incr,
> &index_after_incr);
> @@ -1185,7 +1200,7 @@ vect_set_loop_condition_partial_vectors_avx512 (class
> loop *loop,
> loop handles exactly VF scalars per iteration. */
>
> static gcond *
> -vect_set_loop_condition_normal (loop_vec_info /* loop_vinfo */, edge
> exit_edge,
> +vect_set_loop_condition_normal (loop_vec_info loop_vinfo, edge exit_edge,
> class loop *loop, tree niters, tree step,
> tree final_iv, bool niters_maybe_zero,
> gimple_stmt_iterator loop_cond_gsi)
> @@ -1278,7 +1293,7 @@ vect_set_loop_condition_normal (loop_vec_info /*
> loop_vinfo */, edge exit_edge,
> }
> }
>
> - standard_iv_increment_position (loop, &incr_gsi, &insert_after);
> + vect_iv_increment_position (exit_edge, &incr_gsi, &insert_after);
> create_iv (init, PLUS_EXPR, step, NULL_TREE, loop,
> &incr_gsi, insert_after, &indx_before_incr, &indx_after_incr);
> indx_after_incr = force_gimple_operand_gsi (&loop_cond_gsi,
> indx_after_incr,
> @@ -1446,7 +1461,7 @@ slpeel_tree_duplicate_loop_for_vectorization (class
> loop *loop, edge loop_exit,
> redirect_edge_and_branch (exit, dest);
> }
>
> - /* Only fush the main exit, the remaining exits we need to match the order
> + /* Only flush the main exit, the remaining exits we need to match the order
> in the loop->header which with multiple exits may not be the same. */
> flush_pending_stmts (loop_exit);
>
> @@ -1519,7 +1534,9 @@ slpeel_tree_duplicate_loop_for_vectorization (class
> loop *loop, edge loop_exit,
> SET_PHI_ARG_DEF (alt_lcssa_phi, main_e->dest_idx, new_arg);
> }
> new_arg = alt_res; /* Push it down to the new_loop header. */
> - } else if (!res) {
> + }
> + else if (!res)
> + {
> /* For non-early break we need to keep the possibly live values in
> the exit block. For early break these are kept in the merge
> block in the code above. */
>
--
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)
