Re: [PATCH 1/3]middle-end match.pd: don't emit label if not needed

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

On Tue, Apr 18, 2023 at 12:21 PM Tamar Christina via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Hi All,
>
> This is a small QoL codegen improvement for match.pd to not emit labels when
> they are not needed.  The codegen is nice and there is a small (but consistent)
> improvement in compile time.
>
> Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
>
> Ok for master?

OK.  Btw - how many labels does this remove? (just wc -l the generated files?)

Richard.

> Thanks,
> Tamar
>
> gcc/ChangeLog:
>
>         PR bootstrap/84402
>         * genmatch.cc (dt_simplify::gen_1): Only emit labels if used.
>
> --- inline copy of patch --
> diff --git a/gcc/genmatch.cc b/gcc/genmatch.cc
> index 4fab4135347c43d95546a7df0bb1c4d074937288..638606b2502f640e59527fc5a0b23fa3bedd0cee 100644
> --- a/gcc/genmatch.cc
> +++ b/gcc/genmatch.cc
> @@ -3352,6 +3352,7 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple, operand *result)
>    char local_fail_label[256];
>    snprintf (local_fail_label, 256, "next_after_fail%u", ++fail_label_cnt);
>    fail_label = local_fail_label;
> +  bool needs_label = false;
>
>    /* Analyze captures and perform early-outs on the incoming arguments
>       that cover cases we cannot handle.  */
> @@ -3366,6 +3367,7 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple, operand *result)
>                 fprintf_indent (f, indent,
>                                 "if (TREE_SIDE_EFFECTS (_p%d)) goto %s;\n",
>                                 i, fail_label);
> +               needs_label = true;
>                 if (verbose >= 1)
>                   warning_at (as_a <expr *> (s->match)->ops[i]->location,
>                               "forcing toplevel operand to have no "
> @@ -3381,6 +3383,7 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple, operand *result)
>                 fprintf_indent (f, indent,
>                                 "if (TREE_SIDE_EFFECTS (captures[%d])) "
>                                 "goto %s;\n", i, fail_label);
> +               needs_label = true;
>                 if (verbose >= 1)
>                   warning_at (cinfo.info[i].c->location,
>                               "forcing captured operand to have no "
> @@ -3423,7 +3426,10 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple, operand *result)
>      }
>
>    if (s->kind == simplify::SIMPLIFY)
> -    fprintf_indent (f, indent, "if (UNLIKELY (!dbg_cnt (match))) goto %s;\n", fail_label);
> +    {
> +      fprintf_indent (f, indent, "if (UNLIKELY (!dbg_cnt (match))) goto %s;\n", fail_label);
> +      needs_label = true;
> +    }
>
>    fprintf_indent (f, indent, "if (UNLIKELY (dump_file && (dump_flags & TDF_FOLDING))) "
>            "fprintf (dump_file, \"%s ",
> @@ -3496,9 +3502,12 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple, operand *result)
>                               "res_op->resimplify (%s, valueize);\n",
>                               !e->force_leaf ? "lseq" : "NULL");
>               if (e->force_leaf)
> -               fprintf_indent (f, indent,
> -                               "if (!maybe_push_res_to_seq (res_op, NULL)) "
> -                               "goto %s;\n", fail_label);
> +               {
> +                 fprintf_indent (f, indent,
> +                                 "if (!maybe_push_res_to_seq (res_op, NULL)) "
> +                                 "goto %s;\n", fail_label);
> +                 needs_label = true;
> +               }
>             }
>         }
>        else if (result->type == operand::OP_CAPTURE
> @@ -3554,9 +3563,12 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple, operand *result)
>                   continue;
>                 if (cinfo.info[i].result_use_count
>                     > cinfo.info[i].match_use_count)
> -                 fprintf_indent (f, indent,
> -                                 "if (! tree_invariant_p (captures[%d])) "
> -                                 "goto %s;\n", i, fail_label);
> +                 {
> +                   fprintf_indent (f, indent,
> +                                   "if (! tree_invariant_p (captures[%d])) "
> +                                   "goto %s;\n", i, fail_label);
> +                   needs_label = true;
> +                 }
>               }
>           for (unsigned j = 0; j < e->ops.length (); ++j)
>             {
> @@ -3607,6 +3619,7 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple, operand *result)
>                     {
>                       fprintf_indent (f, indent, "if (!_r)\n");
>                       fprintf_indent (f, indent, "  goto %s;\n", fail_label);
> +                     needs_label = true;
>                     }
>                 }
>             }
> @@ -3647,7 +3660,8 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple, operand *result)
>      }
>    indent -= 2;
>    fprintf_indent (f, indent, "}\n");
> -  fprintf (f, "%s:;\n", fail_label);
> +  if (needs_label)
> +    fprintf (f, "%s:;\n", fail_label);
>    fail_label = NULL;
>  }
>
>
>
>
>
> --