[09/46] Add vec_info::lookup_single_use

This patch adds a helper function for seeing whether there is a single
user of an SSA name, and whether that user has a stmt_vec_info.


2018-07-24  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* tree-vectorizer.h (vec_info::lookup_single_use): Declare.
	* tree-vectorizer.c (vec_info::lookup_single_use): New function.
	* tree-vect-loop.c (vectorizable_reduction): Use it instead of
	a single_imm_use-based sequence.
	* tree-vect-stmts.c (supportable_widening_operation): Likewise.

On Tue, Jul 24, 2018 at 11:56 AM Richard Sandiford
<richard.sandiford@arm.com> wrote:
>
> This patch adds a helper function for seeing whether there is a single
> user of an SSA name, and whether that user has a stmt_vec_info.

OK.

>
> 2018-07-24  Richard Sandiford  <richard.sandiford@arm.com>
>
> gcc/
>         * tree-vectorizer.h (vec_info::lookup_single_use): Declare.
>         * tree-vectorizer.c (vec_info::lookup_single_use): New function.
>         * tree-vect-loop.c (vectorizable_reduction): Use it instead of
>         a single_imm_use-based sequence.
>         * tree-vect-stmts.c (supportable_widening_operation): Likewise.
>
> Index: gcc/tree-vectorizer.h
> ===================================================================
> --- gcc/tree-vectorizer.h       2018-07-24 10:22:27.285336715 +0100
> +++ gcc/tree-vectorizer.h       2018-07-24 10:22:30.401309046 +0100
> @@ -220,6 +220,7 @@ struct vec_info {
>    stmt_vec_info add_stmt (gimple *);
>    stmt_vec_info lookup_stmt (gimple *);
>    stmt_vec_info lookup_def (tree);
> +  stmt_vec_info lookup_single_use (tree);
>
>    /* The type of vectorization.  */
>    vec_kind kind;
> Index: gcc/tree-vectorizer.c
> ===================================================================
> --- gcc/tree-vectorizer.c       2018-07-24 10:22:27.285336715 +0100
> +++ gcc/tree-vectorizer.c       2018-07-24 10:22:30.401309046 +0100
> @@ -548,6 +548,20 @@ vec_info::lookup_def (tree name)
>    return NULL;
>  }
>
> +/* See whether there is a single non-debug statement that uses LHS and
> +   whether that statement has an associated stmt_vec_info.  Return the
> +   stmt_vec_info if so, otherwise return null.  */
> +
> +stmt_vec_info
> +vec_info::lookup_single_use (tree lhs)
> +{
> +  use_operand_p dummy;
> +  gimple *use_stmt;
> +  if (single_imm_use (lhs, &dummy, &use_stmt))
> +    return lookup_stmt (use_stmt);
> +  return NULL;
> +}
> +
>  /* A helper function to free scev and LOOP niter information, as well as
>     clear loop constraint LOOP_C_FINITE.  */
>
> Index: gcc/tree-vect-loop.c
> ===================================================================
> --- gcc/tree-vect-loop.c        2018-07-24 10:22:27.277336786 +0100
> +++ gcc/tree-vect-loop.c        2018-07-24 10:22:30.401309046 +0100
> @@ -6138,6 +6138,7 @@ vectorizable_reduction (gimple *stmt, gi
>
>    if (gimple_code (stmt) == GIMPLE_PHI)
>      {
> +      tree phi_result = gimple_phi_result (stmt);
>        /* Analysis is fully done on the reduction stmt invocation.  */
>        if (! vec_stmt)
>         {
> @@ -6158,7 +6159,8 @@ vectorizable_reduction (gimple *stmt, gi
>        if (STMT_VINFO_IN_PATTERN_P (vinfo_for_stmt (reduc_stmt)))
>         reduc_stmt = STMT_VINFO_RELATED_STMT (vinfo_for_stmt (reduc_stmt));
>
> -      if (STMT_VINFO_VEC_REDUCTION_TYPE (vinfo_for_stmt (reduc_stmt))
> +      stmt_vec_info reduc_stmt_info = vinfo_for_stmt (reduc_stmt);
> +      if (STMT_VINFO_VEC_REDUCTION_TYPE (reduc_stmt_info)
>           == EXTRACT_LAST_REDUCTION)
>         /* Leave the scalar phi in place.  */
>         return true;
> @@ -6185,15 +6187,12 @@ vectorizable_reduction (gimple *stmt, gi
>        else
>         ncopies = vect_get_num_copies (loop_vinfo, vectype_in);
>
> -      use_operand_p use_p;
> -      gimple *use_stmt;
> +      stmt_vec_info use_stmt_info;
>        if (ncopies > 1
> -         && (STMT_VINFO_RELEVANT (vinfo_for_stmt (reduc_stmt))
> -             <= vect_used_only_live)
> -         && single_imm_use (gimple_phi_result (stmt), &use_p, &use_stmt)
> -         && (use_stmt == reduc_stmt
> -             || (STMT_VINFO_RELATED_STMT (vinfo_for_stmt (use_stmt))
> -                 == reduc_stmt)))
> +         && STMT_VINFO_RELEVANT (reduc_stmt_info) <= vect_used_only_live
> +         && (use_stmt_info = loop_vinfo->lookup_single_use (phi_result))
> +         && (use_stmt_info == reduc_stmt_info
> +             || STMT_VINFO_RELATED_STMT (use_stmt_info) == reduc_stmt))
>         single_defuse_cycle = true;
>
>        /* Create the destination vector  */
> @@ -6955,13 +6954,13 @@ vectorizable_reduction (gimple *stmt, gi
>     This only works when we see both the reduction PHI and its only consumer
>     in vectorizable_reduction and there are no intermediate stmts
>     participating.  */
> -  use_operand_p use_p;
> -  gimple *use_stmt;
> +  stmt_vec_info use_stmt_info;
> +  tree reduc_phi_result = gimple_phi_result (reduc_def_stmt);
>    if (ncopies > 1
>        && (STMT_VINFO_RELEVANT (stmt_info) <= vect_used_only_live)
> -      && single_imm_use (gimple_phi_result (reduc_def_stmt), &use_p, &use_stmt)
> -      && (use_stmt == stmt
> -         || STMT_VINFO_RELATED_STMT (vinfo_for_stmt (use_stmt)) == stmt))
> +      && (use_stmt_info = loop_vinfo->lookup_single_use (reduc_phi_result))
> +      && (use_stmt_info == stmt_info
> +         || STMT_VINFO_RELATED_STMT (use_stmt_info) == stmt))
>      {
>        single_defuse_cycle = true;
>        epilog_copies = 1;
> Index: gcc/tree-vect-stmts.c
> ===================================================================
> --- gcc/tree-vect-stmts.c       2018-07-24 10:22:27.281336751 +0100
> +++ gcc/tree-vect-stmts.c       2018-07-24 10:22:30.401309046 +0100
> @@ -10310,14 +10310,11 @@ supportable_widening_operation (enum tre
>               same operation.  One such an example is s += a * b, where elements
>               in a and b cannot be reordered.  Here we check if the vector defined
>               by STMT is only directly used in the reduction statement.  */
> -          tree lhs = gimple_assign_lhs (stmt);
> -          use_operand_p dummy;
> -          gimple *use_stmt;
> -          stmt_vec_info use_stmt_info = NULL;
> -          if (single_imm_use (lhs, &dummy, &use_stmt)
> -              && (use_stmt_info = vinfo_for_stmt (use_stmt))
> -              && STMT_VINFO_DEF_TYPE (use_stmt_info) == vect_reduction_def)
> -            return true;
> +         tree lhs = gimple_assign_lhs (stmt);
> +         stmt_vec_info use_stmt_info = loop_info->lookup_single_use (lhs);
> +         if (use_stmt_info
> +             && STMT_VINFO_DEF_TYPE (use_stmt_info) == vect_reduction_def)
> +           return true;
>          }
>        c1 = VEC_WIDEN_MULT_LO_EXPR;
>        c2 = VEC_WIDEN_MULT_HI_EXPR;