Re: [PATCH 2/4] Allow match-and-simplified phiopt to run in early phiopt

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

On Mon, Jun 28, 2021 at 1:27 AM apinski--- via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> From: Andrew Pinski <apinski@marvell.com>
>
> To move a few things more to match-and-simplify from phiopt,
> we need to allow match_simplify_replacement to run in early
> phiopt. To do this we add a replacement for gimple_simplify
> that is explictly for phiopt.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no
> regressions.

OK.

> gcc/ChangeLog:
>
>         * tree-ssa-phiopt.c (match_simplify_replacement):
>         Add early_p argument. Call gimple_simplify_phiopt
>         instead of gimple_simplify.
>         (tree_ssa_phiopt_worker): Update call to
>         match_simplify_replacement and allow unconditionally.
>         (phiopt_early_allow): New function.
>         (gimple_simplify_phiopt): New function.
> ---
>  gcc/tree-ssa-phiopt.c | 89 ++++++++++++++++++++++++++++++++++---------
>  1 file changed, 70 insertions(+), 19 deletions(-)
>
> diff --git a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c
> index ab12e85569d..17bc597851b 100644
> --- a/gcc/tree-ssa-phiopt.c
> +++ b/gcc/tree-ssa-phiopt.c
> @@ -50,12 +50,13 @@ along with GCC; see the file COPYING3.  If not see
>  #include "gimple-fold.h"
>  #include "internal-fn.h"
>  #include "gimple-range.h"
> +#include "gimple-match.h"
>
>  static unsigned int tree_ssa_phiopt_worker (bool, bool, bool);
>  static bool two_value_replacement (basic_block, basic_block, edge, gphi *,
>                                    tree, tree);
>  static bool match_simplify_replacement (basic_block, basic_block,
> -                                       edge, edge, gphi *, tree, tree);
> +                                       edge, edge, gphi *, tree, tree, bool);
>  static gphi *factor_out_conditional_conversion (edge, edge, gphi *, tree, tree,
>                                                 gimple *);
>  static int value_replacement (basic_block, basic_block,
> @@ -345,9 +346,9 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p)
>           /* Do the replacement of conditional if it can be done.  */
>           if (!early_p && two_value_replacement (bb, bb1, e2, phi, arg0, arg1))
>             cfgchanged = true;
> -         else if (!early_p
> -                  && match_simplify_replacement (bb, bb1, e1, e2, phi,
> -                                                 arg0, arg1))
> +         else if (match_simplify_replacement (bb, bb1, e1, e2, phi,
> +                                              arg0, arg1,
> +                                              early_p))
>             cfgchanged = true;
>           else if (abs_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
>             cfgchanged = true;
> @@ -811,6 +812,67 @@ two_value_replacement (basic_block cond_bb, basic_block middle_bb,
>    return true;
>  }
>
> +/* Return TRUE if CODE should be allowed during early phiopt.
> +   Currently this is to allow MIN/MAX and ABS/NEGATE.  */
> +static bool
> +phiopt_early_allow (enum tree_code code)
> +{
> +  switch (code)
> +    {
> +      case MIN_EXPR:
> +      case MAX_EXPR:
> +      case ABS_EXPR:
> +      case ABSU_EXPR:
> +      case NEGATE_EXPR:
> +      case SSA_NAME:
> +       return true;
> +      default:
> +       return false;
> +    }
> +}
> +
> +/* gimple_simplify_phiopt is like gimple_simplify but designed for PHIOPT.
> +   Return NULL if nothing can be simplified or the resulting simplified value
> +   with parts pushed if EARLY_P was true. Also rejects non allowed tree code
> +   if EARLY_P is set.
> +   Takes the comparison from COMP_STMT and two args, ARG0 and ARG1 and tries
> +   to simplify CMP ? ARG0 : ARG1.  */
> +static tree
> +gimple_simplify_phiopt (bool early_p, tree type, gimple *comp_stmt,
> +                       tree arg0, tree arg1,
> +                       gimple_seq *seq)
> +{
> +  tree result;
> +  enum tree_code comp_code = gimple_cond_code (comp_stmt);
> +  location_t loc = gimple_location (comp_stmt);
> +  tree cmp0 = gimple_cond_lhs (comp_stmt);
> +  tree cmp1 = gimple_cond_rhs (comp_stmt);
> +  /* To handle special cases like floating point comparison, it is easier and
> +     less error-prone to build a tree and gimplify it on the fly though it is
> +     less efficient.
> +     Don't use fold_build2 here as that might create (bool)a instead of just
> +     "a != 0".  */
> +  tree cond = build2_loc (loc, comp_code, boolean_type_node,
> +                         cmp0, cmp1);
> +  gimple_match_op op (gimple_match_cond::UNCOND,
> +                     COND_EXPR, type, cond, arg0, arg1);
> +
> +  if (op.resimplify (early_p ? NULL : seq, follow_all_ssa_edges))
> +    {
> +      /* Early we want only to allow some generated tree codes. */
> +      if (!early_p
> +         || op.code.is_tree_code ()
> +         || phiopt_early_allow ((tree_code)op.code))
> +       {
> +         result = maybe_push_res_to_seq (&op, seq);
> +         if (result)
> +           return result;
> +       }
> +    }
> +
> +  return NULL;
> +}
> +
>  /*  The function match_simplify_replacement does the main work of doing the
>      replacement using match and simplify.  Return true if the replacement is done.
>      Otherwise return false.
> @@ -820,10 +882,9 @@ two_value_replacement (basic_block cond_bb, basic_block middle_bb,
>  static bool
>  match_simplify_replacement (basic_block cond_bb, basic_block middle_bb,
>                             edge e0, edge e1, gphi *phi,
> -                           tree arg0, tree arg1)
> +                           tree arg0, tree arg1, bool early_p)
>  {
>    gimple *stmt;
> -  tree cond;
>    gimple_stmt_iterator gsi;
>    edge true_edge, false_edge;
>    gimple_seq seq = NULL;
> @@ -884,15 +945,6 @@ match_simplify_replacement (basic_block cond_bb, basic_block middle_bb,
>
>    stmt = last_stmt (cond_bb);
>
> -  /* To handle special cases like floating point comparison, it is easier and
> -     less error-prone to build a tree and gimplify it on the fly though it is
> -     less efficient.
> -     Don't use fold_build2 here as that might create (bool)a instead of just
> -     "a != 0".  */
> -  cond = build2_loc (gimple_location (stmt),
> -                    gimple_cond_code (stmt), boolean_type_node,
> -                    gimple_cond_lhs (stmt), gimple_cond_rhs (stmt));
> -
>    /* We need to know which is the true edge and which is the false
>       edge so that we know when to invert the condition below.  */
>    extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge);
> @@ -900,10 +952,9 @@ match_simplify_replacement (basic_block cond_bb, basic_block middle_bb,
>      std::swap (arg0, arg1);
>
>    tree type = TREE_TYPE (gimple_phi_result (phi));
> -  result = gimple_simplify (COND_EXPR, type,
> -                           cond,
> -                           arg0, arg1,
> -                           &seq, NULL);
> +  result = gimple_simplify_phiopt (early_p, type, stmt,
> +                                  arg0, arg1,
> +                                  &seq);
>    if (!result)
>      return false;
>
> --
> 2.27.0
>