Re: [PATCH] Dump if a pattern fails after having printed applying it

[Andrew Pinski <pinskia@gmail.com>]

On Wed, May 24, 2023 at 2:03 AM Richard Biener via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> On Wed, May 24, 2023 at 1:16 AM Andrew Pinski via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > While trying to understand how to use the ! operand for match
> > patterns, I noticed that the debug dumps would print out applying
> > a pattern but nothing when it was rejected in the end. This was confusing
> > me.
> > This adds that by emitting a dump for the failed case.
> > Note the patch is little more complex as we don't want to print out
> > if debug counter rejected the pattern and then we need to fix up
> > when we mark needing a label or not.
> >
> > OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
>
> Hmm, can we maybe simply move the
>
>                                                 if (UNLIKELY
> (debug_dump)) fprintf (dump_file, "Applying pattern %s:%d, %s:%d\n",
> "match.pd", 1157, __FILE__, __LINE__);
>
> right before the return true; instead?

Yes that should work. Let me do a patch for that.

Thanks,
Andrew

>
> > gcc/ChangeLog:
> >
> >         * genmatch.cc (needs_label): New variable
> >         (expr::gen_transform): Set needs_label
> >         if we use the local_label.
> >         (dt_simplify::gen_1): Use `_1` for the debug count label.
> >         After the local label, emit debug print for the failure.
> >         Emit `_1` label if needed.
> > ---
> >  gcc/genmatch.cc | 28 ++++++++++++++++++++++++----
> >  1 file changed, 24 insertions(+), 4 deletions(-)
> >
> > diff --git a/gcc/genmatch.cc b/gcc/genmatch.cc
> > index 177c13d87cb..2ea80d341a2 100644
> > --- a/gcc/genmatch.cc
> > +++ b/gcc/genmatch.cc
> > @@ -2433,6 +2433,7 @@ capture_info::walk_c_expr (c_expr *e)
> >  /* The current label failing the current matched pattern during
> >     code generation.  */
> >  static char *fail_label;
> > +static bool needs_label;
> >
> >  /* Code generation off the decision tree and the refered AST nodes.  */
> >
> > @@ -2611,6 +2612,7 @@ expr::gen_transform (FILE *f, int indent, const char *dest, bool gimple,
> >        fprintf_indent (f, indent,
> >                       "if (!_r%d) goto %s;\n",
> >                       depth, fail_label);
> > +      needs_label = true;
> >        if (*opr == CONVERT_EXPR)
> >         {
> >           indent -= 4;
> > @@ -2640,11 +2642,13 @@ expr::gen_transform (FILE *f, int indent, const char *dest, bool gimple,
> >         {
> >           fprintf_indent (f, indent, "if (!_r%d)\n", depth);
> >           fprintf_indent (f, indent, "  goto %s;\n", fail_label);
> > +         needs_label = true;
> >         }
> >        if (force_leaf)
> >         {
> >           fprintf_indent (f, indent, "if (EXPR_P (_r%d))\n", depth);
> >           fprintf_indent (f, indent, "  goto %s;\n", fail_label);
> > +         needs_label = true;
> >         }
> >        if (*opr == CONVERT_EXPR)
> >         {
> > @@ -3409,7 +3413,8 @@ 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;
> > +  needs_label = false;
> > +  bool needs_label_1 = false;
> >
> >    /* Analyze captures and perform early-outs on the incoming arguments
> >       that cover cases we cannot handle.  */
> > @@ -3484,8 +3489,8 @@ 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);
> > -      needs_label = true;
> > +      fprintf_indent (f, indent, "if (UNLIKELY (!dbg_cnt (match))) goto %s_1;\n", fail_label);
> > +      needs_label_1 = true;
> >      }
> >
> >    fprintf_indent (f, indent, "if (UNLIKELY (debug_dump)) "
> > @@ -3718,7 +3723,22 @@ dt_simplify::gen_1 (FILE *f, int indent, bool gimple, operand *result)
> >    indent -= 2;
> >    fprintf_indent (f, indent, "}\n");
> >    if (needs_label)
> > -    fprintf (f, "%s:;\n", fail_label);
> > +    {
> > +      fprintf (f, "%s:;\n", fail_label);
> > +      if (s->kind == simplify::SIMPLIFY)
> > +       {
> > +         fprintf_indent (f, indent, "if (UNLIKELY (debug_dump)) "
> > +                         "fprintf (dump_file, \"Pattern failed ");
> > +         fprintf (f, "%%s:%%d, %%s:%%d\\n\", ");
> > +         output_line_directive (f,
> > +                                result ? result->location : s->match->location, true,
> > +                                true);
> > +         fprintf (f, ", __FILE__, __LINE__);\n");
> > +       }
> > +    }
> > +  if (needs_label_1)
> > +    fprintf (f, "%s_1:;\n", fail_label);
> > +  needs_label = false;
> >    fail_label = NULL;
> >  }
> >
> > --
> > 2.31.1
> >