Thanks Richi. I am gonna merge it after Richard's final approve.



juzhe.zhong@rivai.ai
 
From: Richard Biener
Date: 2023-06-02 16:56
To: juzhe.zhong@rivai.ai
CC: gcc-patches; richard.sandiford; linkw
Subject: Re: [PATCH V3] VECT: Change flow of decrement IV
On Thu, 1 Jun 2023, juzhe.zhong@rivai.ai wrote:
 
> This patch is no difference from V2.
> Just add PR tree-optimization/109971 as Kewen's suggested.
> 
> Already bootstrapped and Regression on X86 no difference.
> 
> Ok for trunk ?
 
OK.
 
Richard.
 
> 
> juzhe.zhong@rivai.ai
>  
> From: juzhe.zhong
> Date: 2023-06-01 12:36
> To: gcc-patches
> CC: richard.sandiford; rguenther; linkw; Ju-Zhe Zhong
> Subject: [PATCH V3] VECT: Change flow of decrement IV
> From: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>
>  
> Follow Richi's suggestion, I change current decrement IV flow from:
>  
> do {
>    remain -= MIN (vf, remain);
> } while (remain != 0);
>  
> into:
>  
> do {
>    old_remain = remain;
>    len = MIN (vf, remain);
>    remain -= vf;
> } while (old_remain >= vf);
>  
> to enhance SCEV.
>  
> Include fixes from kewen.
>  
>  
> This patch will need to wait for Kewen's test feedback.
>  
> Testing on X86 is on-going
>  
> Co-Authored by: Kewen Lin  <linkw@linux.ibm.com>
>  
>   PR tree-optimization/109971
>  
> gcc/ChangeLog:
>  
>         * tree-vect-loop-manip.cc (vect_set_loop_controls_directly): Change decrement IV flow.
>         (vect_set_loop_condition_partial_vectors): Ditto.
>  
> ---
> gcc/tree-vect-loop-manip.cc | 36 +++++++++++++++++++++++++-----------
> 1 file changed, 25 insertions(+), 11 deletions(-)
>  
> diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
> index acf3642ceb2..3f735945e67 100644
> --- a/gcc/tree-vect-loop-manip.cc
> +++ b/gcc/tree-vect-loop-manip.cc
> @@ -483,7 +483,7 @@ vect_set_loop_controls_directly (class loop *loop, loop_vec_info loop_vinfo,
> gimple_stmt_iterator loop_cond_gsi,
> rgroup_controls *rgc, tree niters,
> tree niters_skip, bool might_wrap_p,
> - tree *iv_step)
> + tree *iv_step, tree *compare_step)
> {
>    tree compare_type = LOOP_VINFO_RGROUP_COMPARE_TYPE (loop_vinfo);
>    tree iv_type = LOOP_VINFO_RGROUP_IV_TYPE (loop_vinfo);
> @@ -538,9 +538,9 @@ vect_set_loop_controls_directly (class loop *loop, loop_vec_info loop_vinfo,
>    ...
>    vect__4.8_28 = .LEN_LOAD (_17, 32B, _36, 0);
>    ...
> -    ivtmp_35 = ivtmp_9 - _36;
> +    ivtmp_35 = ivtmp_9 - POLY_INT_CST [4, 4];
>    ...
> -    if (ivtmp_35 != 0)
> +    if (ivtmp_9 > POLY_INT_CST [4, 4])
>      goto <bb 4>; [83.33%]
>    else
>      goto <bb 5>; [16.67%]
> @@ -549,13 +549,15 @@ vect_set_loop_controls_directly (class loop *loop, loop_vec_info loop_vinfo,
>        tree step = rgc->controls.length () == 1 ? rgc->controls[0]
>        : make_ssa_name (iv_type);
>        /* Create decrement IV.  */
> -      create_iv (nitems_total, MINUS_EXPR, step, NULL_TREE, loop, &incr_gsi,
> - insert_after, &index_before_incr, &index_after_incr);
> +      create_iv (nitems_total, MINUS_EXPR, nitems_step, NULL_TREE, loop,
> + &incr_gsi, insert_after, &index_before_incr,
> + &index_after_incr);
>        gimple_seq_add_stmt (header_seq, gimple_build_assign (step, MIN_EXPR,
>     index_before_incr,
>     nitems_step));
>        *iv_step = step;
> -      return index_after_incr;
> +      *compare_step = nitems_step;
> +      return index_before_incr;
>      }
>    /* Create increment IV.  */
> @@ -825,6 +827,7 @@ vect_set_loop_condition_partial_vectors (class loop *loop,
>       arbitrarily pick the last.  */
>    tree test_ctrl = NULL_TREE;
>    tree iv_step = NULL_TREE;
> +  tree compare_step = NULL_TREE;
>    rgroup_controls *rgc;
>    rgroup_controls *iv_rgc = nullptr;
>    unsigned int i;
> @@ -861,7 +864,7 @@ vect_set_loop_condition_partial_vectors (class loop *loop,
> &preheader_seq, &header_seq,
> loop_cond_gsi, rgc, niters,
> niters_skip, might_wrap_p,
> - &iv_step);
> + &iv_step, &compare_step);
>     iv_rgc = rgc;
>   }
> @@ -884,10 +887,21 @@ vect_set_loop_condition_partial_vectors (class loop *loop,
>    /* Get a boolean result that tells us whether to iterate.  */
>    edge exit_edge = single_exit (loop);
> -  tree_code code = (exit_edge->flags & EDGE_TRUE_VALUE) ? EQ_EXPR : NE_EXPR;
> -  tree zero_ctrl = build_zero_cst (TREE_TYPE (test_ctrl));
> -  gcond *cond_stmt = gimple_build_cond (code, test_ctrl, zero_ctrl,
> - NULL_TREE, NULL_TREE);
> +  gcond *cond_stmt;
> +  if (LOOP_VINFO_USING_DECREMENTING_IV_P (loop_vinfo))
> +    {
> +      gcc_assert (compare_step);
> +      tree_code code = (exit_edge->flags & EDGE_TRUE_VALUE) ? LE_EXPR : GT_EXPR;
> +      cond_stmt = gimple_build_cond (code, test_ctrl, compare_step, NULL_TREE,
> +      NULL_TREE);
> +    }
> +  else
> +    {
> +      tree_code code = (exit_edge->flags & EDGE_TRUE_VALUE) ? EQ_EXPR : NE_EXPR;
> +      tree zero_ctrl = build_zero_cst (TREE_TYPE (test_ctrl));
> +      cond_stmt
> + = gimple_build_cond (code, test_ctrl, zero_ctrl, NULL_TREE, NULL_TREE);
> +    }
>    gsi_insert_before (&loop_cond_gsi, cond_stmt, GSI_SAME_STMT);
>    /* The loop iterates (NITERS - 1) / VF + 1 times.
> 
 
-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg,
Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
HRB 36809 (AG Nuernberg)