Re: [PATCH] Check nonlinear iv in vect_can_advance_ivs_p.

[Richard Biener <richard.guenther@gmail.com>]

On Thu, Sep 29, 2022 at 7:03 AM liuhongt via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> vectorizable_nonlinear_induction doesn't always guard
> vect_peel_nonlinear_iv_init when it's called by
> vect_update_ivs_after_vectorizer which is supposed to be guarded
> by vect_can_advance_ivs_p. The patch put part codes from
> vectorizable_nonlinear_induction into a new function
> vect_can_peel_nonlinear_iv_p, and make vect_can_advcance_ivs_p call it.
>
> Also this patch fix a typo in my initial patch as bellow.
> -  if (!LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo)
> -      && induction_type == vect_step_op_mul)
>    if (!INTEGRAL_TYPE_P (TREE_TYPE (vectype)))
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> Ok for trunk?

OK.

Thanks,
Richard.

> gcc/ChangeLog:
>
>         PR tree-optimization/107055
>         * tree-vect-loop-manip.cc (vect_can_advance_ivs_p): Check for
>         nonlinear induction variables.
>         * tree-vect-loop.cc (vect_can_peel_nonlinear_iv_p): New
>         functions.
>         (vectorizable_nonlinear_induction): Put part codes into
>         vect_can_peel_nonlinear_iv_p.
>         * tree-vectorizer.h (vect_can_peel_nonlinear_iv_p): Declare.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.target/i386/pr107055.c: New test.
> ---
>  gcc/testsuite/gcc.target/i386/pr107055.c |  4 ++
>  gcc/tree-vect-loop-manip.cc              | 10 +++
>  gcc/tree-vect-loop.cc                    | 82 ++++++++++++++----------
>  gcc/tree-vectorizer.h                    |  3 +
>  4 files changed, 64 insertions(+), 35 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr107055.c
>
> diff --git a/gcc/testsuite/gcc.target/i386/pr107055.c b/gcc/testsuite/gcc.target/i386/pr107055.c
> new file mode 100644
> index 00000000000..63bcb3d742e
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr107055.c
> @@ -0,0 +1,4 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -fno-tree-dce -fno-vect-cost-model -ftree-vectorize -fprofile-arcs" } */
> +
> +#include "../../gcc.dg/torture/pr24257.c"
> diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
> index 74b221a973c..1d96130c985 100644
> --- a/gcc/tree-vect-loop-manip.cc
> +++ b/gcc/tree-vect-loop-manip.cc
> @@ -1413,6 +1413,7 @@ vect_can_advance_ivs_p (loop_vec_info loop_vinfo)
>    for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
>      {
>        tree evolution_part;
> +      enum vect_induction_op_type induction_type;
>
>        gphi *phi = gsi.phi ();
>        stmt_vec_info phi_info = loop_vinfo->lookup_stmt (phi);
> @@ -1432,6 +1433,15 @@ vect_can_advance_ivs_p (loop_vec_info loop_vinfo)
>           continue;
>         }
>
> +      induction_type = STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE (phi_info);
> +      if (induction_type != vect_step_op_add)
> +       {
> +         if (!vect_can_peel_nonlinear_iv_p (loop_vinfo, induction_type))
> +           return false;
> +
> +         continue;
> +       }
> +
>        /* Analyze the evolution function.  */
>
>        evolution_part = STMT_VINFO_LOOP_PHI_EVOLUTION_PART (phi_info);
> diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> index aabdc6f2d81..2536cc3cf49 100644
> --- a/gcc/tree-vect-loop.cc
> +++ b/gcc/tree-vect-loop.cc
> @@ -8558,6 +8558,50 @@ vect_update_nonlinear_iv (gimple_seq* stmts, tree vectype,
>    return vec_def;
>
>  }
> +
> +/* Return true if vectorizer can peel for nonlinear iv.  */
> +bool
> +vect_can_peel_nonlinear_iv_p (loop_vec_info loop_vinfo,
> +                             enum vect_induction_op_type induction_type)
> +{
> +  tree niters_skip;
> +  /* Init_expr will be update by vect_update_ivs_after_vectorizer,
> +     if niters is unkown:
> +     For shift, when shift mount >= precision, there would be UD.
> +     For mult, don't known how to generate
> +     init_expr * pow (step, niters) for variable niters.
> +     For neg, it should be ok, since niters of vectorized main loop
> +     will always be multiple of 2.  */
> +  if (!LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo)
> +      && induction_type != vect_step_op_neg)
> +    {
> +      if (dump_enabled_p ())
> +       dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> +                        "Peeling for epilogue is not supported"
> +                        " for nonlinear induction except neg"
> +                        " when iteration count is unknown.\n");
> +      return false;
> +    }
> +
> +  /* Also doens't support peel for neg when niter is variable.
> +     ??? generate something like niter_expr & 1 ? init_expr : -init_expr?  */
> +  niters_skip = LOOP_VINFO_MASK_SKIP_NITERS (loop_vinfo);
> +  if ((niters_skip != NULL_TREE
> +       && TREE_CODE (niters_skip) != INTEGER_CST)
> +      || (!vect_use_loop_mask_for_alignment_p (loop_vinfo)
> +         && LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo) < 0))
> +    {
> +      if (dump_enabled_p ())
> +       dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> +                        "Peeling for alignement is not supported"
> +                        " for nonlinear induction when niters_skip"
> +                        " is not constant.\n");
> +      return false;
> +    }
> +
> +  return true;
> +}
> +
>  /* Function vectorizable_induction
>
>     Check if STMT_INFO performs an nonlinear induction computation that can be
> @@ -8628,42 +8672,9 @@ vectorizable_nonlinear_induction (loop_vec_info loop_vinfo,
>        return false;
>      }
>
> -  /* Init_expr will be update by vect_update_ivs_after_vectorizer,
> -     if niters is unkown:
> -     For shift, when shift mount >= precision, there would be UD.
> -     For mult, don't known how to generate
> -     init_expr * pow (step, niters) for variable niters.
> -     For neg, it should be ok, since niters of vectorized main loop
> -     will always be multiple of 2.  */
> -  if (!LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo)
> -      && induction_type != vect_step_op_neg)
> -    {
> -      if (dump_enabled_p ())
> -       dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> -                        "Peeling for epilogue is not supported"
> -                        " for nonlinear induction except neg"
> -                        " when iteration count is unknown.\n");
> -      return false;
> -    }
> -
> -  /* Also doens't support peel for neg when niter is variable.
> -     ??? generate something like niter_expr & 1 ? init_expr : -init_expr?  */
> -  niters_skip = LOOP_VINFO_MASK_SKIP_NITERS (loop_vinfo);
> -  if ((niters_skip != NULL_TREE
> -       && TREE_CODE (niters_skip) != INTEGER_CST)
> -      || (!vect_use_loop_mask_for_alignment_p (loop_vinfo)
> -         && LOOP_VINFO_PEELING_FOR_ALIGNMENT (loop_vinfo) < 0))
> -    {
> -      if (dump_enabled_p ())
> -       dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> -                        "Peeling for alignement is not supported"
> -                        " for nonlinear induction when niters_skip"
> -                        " is not constant.\n");
> -      return false;
> -    }
> +  if (!vect_can_peel_nonlinear_iv_p (loop_vinfo, induction_type))
> +    return false;
>
> -  if (!LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo)
> -      && induction_type == vect_step_op_mul)
>    if (!INTEGRAL_TYPE_P (TREE_TYPE (vectype)))
>      {
>        if (dump_enabled_p ())
> @@ -8799,6 +8810,7 @@ vectorizable_nonlinear_induction (loop_vec_info loop_vinfo,
>
>    gimple_seq stmts = NULL;
>
> +  niters_skip = LOOP_VINFO_MASK_SKIP_NITERS (loop_vinfo);
>    /* If we are using the loop mask to "peel" for alignment then we need
>       to adjust the start value here.  */
>    if (niters_skip != NULL_TREE)
> diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
> index 5e75ed1532b..4870c754499 100644
> --- a/gcc/tree-vectorizer.h
> +++ b/gcc/tree-vectorizer.h
> @@ -2343,6 +2343,9 @@ extern tree cse_and_gimplify_to_preheader (loop_vec_info, tree);
>  /* Nonlinear induction.  */
>  extern tree vect_peel_nonlinear_iv_init (gimple_seq*, tree, tree,
>                                          tree, enum vect_induction_op_type);
> +extern bool
> +vect_can_peel_nonlinear_iv_p (loop_vec_info loop_vinfo,
> +                             enum vect_induction_op_type induction_type);
>
>  /* In tree-vect-slp.cc.  */
>  extern void vect_slp_init (void);
> --
> 2.18.1
>