doc: clean up references to `Tracking Locations'.

[bison.git] / src / reduce.c

diff --git a/src/reduce.c b/src/reduce.c
index bef2ae90307d279f78161917446f4ebca66482b6..7a30e55532b2f197da93c46f36947f3ead6e75da 100644 (file)
--- a/src/reduce.c
+++ b/src/reduce.c
@@ -1,22 +1,22 @@
 /* Grammar reduction for Bison.
 /* Grammar reduction for Bison.

-   Copyright 1988, 1989, 2000, 2001  Free Software Foundation, Inc.
+
+   Copyright (C) 1988-1989, 2000-2003, 2005-2011 Free Software
+   Foundation, Inc.

 
    This file is part of Bison, the GNU Compiler Compiler.
 
 
    This file is part of Bison, the GNU Compiler Compiler.
 

-   Bison is free software; you can redistribute it and/or modify
+   This program is free software: you can redistribute it and/or modify

    it under the terms of the GNU General Public License as published by
    it under the terms of the GNU General Public License as published by

-   the Free Software Foundation; either version 2, or (at your option)
-   any later version.
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.

 
 

-   Bison is distributed in the hope that it will be useful,
+   This program is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License

-   along with Bison; see the file COPYING.  If not, write to
-   the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-   Boston, MA 02111-1307, USA.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

 
 
 /* Reduce the grammar: Find and eliminate unreachable terminals,
 
 
 /* Reduce the grammar: Find and eliminate unreachable terminals,


@@ -25,19 +25,20 @@
 /* Don't eliminate unreachable terminals: They may be used by the
    user's parser.  */
 
 /* Don't eliminate unreachable terminals: They may be used by the
    user's parser.  */
 

+#include <config.h>

 #include "system.h"
 #include "system.h"

-#include "getargs.h"
+
+#include <bitset.h>
+#include <quotearg.h>
+
+#include "complain.h"

 #include "files.h"
 #include "files.h"

-#include "symtab.h"
+#include "getargs.h"

 #include "gram.h"
 #include "gram.h"

-#include "complain.h"
-#include "reduce.h"
+#include "print-xml.h"

 #include "reader.h"
 #include "reader.h"

-#include "getargs.h"
-#include "bitset.h"
-
-typedef short *rule;
-
+#include "reduce.h"
+#include "symtab.h"

 
 /* Set of all nonterminals which are not useless.  */
 static bitset N;
 
 /* Set of all nonterminals which are not useless.  */
 static bitset N;


@@ -52,10 +53,10 @@ static bitset V;
    `useless', but no warning should be issued).  */
 static bitset V1;
 
    `useless', but no warning should be issued).  */
 static bitset V1;
 

-static int nuseful_productions;
-static int nuseless_productions;
+static rule_number nuseful_productions;
+rule_number nuseless_productions;

 static int nuseful_nonterminals;
 static int nuseful_nonterminals;

-int nuseless_nonterminals;
+symbol_number nuseless_nonterminals;

 \f
 /*-------------------------------------------------------------------.
 | Another way to do this would be with a set for each production and |
 \f
 /*-------------------------------------------------------------------.
 | Another way to do this would be with a set for each production and |


@@ -64,18 +65,17 @@ int nuseless_nonterminals;
 `-------------------------------------------------------------------*/
 
 static bool
 `-------------------------------------------------------------------*/
 
 static bool

-useful_production (int i, bitset N0)
+useful_production (rule_number r, bitset N0)

 {
 {

-  rule r;
-  short n;
+  item_number *rhsp;

 
   /* A production is useful if all of the nonterminals in its appear
      in the set of useful nonterminals.  */
 
 
   /* A production is useful if all of the nonterminals in its appear
      in the set of useful nonterminals.  */
 

-  for (r = &ritem[rules[i].rhs]; *r >= 0; r++)
-    if (ISVAR (n = *r) && !bitset_test (N0, n - ntokens))
-      return FALSE;
-  return TRUE;
+  for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp)
+    if (ISVAR (*rhsp) && !bitset_test (N0, *rhsp - ntokens))
+      return false;
+  return true;

 }
 
 
 }
 
 


@@ -87,7 +87,7 @@ static void
 useless_nonterminals (void)
 {
   bitset Np, Ns;
 useless_nonterminals (void)
 {
   bitset Np, Ns;

-  int i;
+  rule_number r;

 
   /* N is set as built.  Np is set being built this iteration. P is
      set of all productions which have a RHS all in N.  */
 
   /* N is set as built.  Np is set being built this iteration. P is
      set of all productions which have a RHS all in N.  */


@@ -114,12 +114,12 @@ useless_nonterminals (void)
   while (1)
     {
       bitset_copy (Np, N);
   while (1)
     {
       bitset_copy (Np, N);

-      for (i = 1; i <= nrules; i++)
-       if (!bitset_test (P, i)
-           && useful_production (i, N))
+      for (r = 0; r < nrules; r++)
+       if (!bitset_test (P, r)
+           && useful_production (r, N))

          {
          {

-           bitset_set (Np, rules[i].lhs - ntokens);
-           bitset_set (P, i);
+           bitset_set (Np, rules[r].lhs->number - ntokens);
+           bitset_set (P, r);

          }
       if (bitset_equal_p (N, Np))
        break;
          }
       if (bitset_equal_p (N, Np))
        break;


@@ -136,9 +136,6 @@ static void
 inaccessable_symbols (void)
 {
   bitset Vp, Vs, Pp;
 inaccessable_symbols (void)
 {
   bitset Vp, Vs, Pp;

-  int i;
-  short t;
-  rule r;

 
   /* Find out which productions are reachable and which symbols are
      used.  Starting with an empty set of productions and a set of
 
   /* Find out which productions are reachable and which symbols are
      used.  Starting with an empty set of productions and a set of


@@ -164,26 +161,28 @@ inaccessable_symbols (void)
      user can know.  */
 
   Vp = bitset_create (nsyms, BITSET_FIXED);
      user can know.  */
 
   Vp = bitset_create (nsyms, BITSET_FIXED);

-  Pp = bitset_create (nrules + 1, BITSET_FIXED);
+  Pp = bitset_create (nrules, BITSET_FIXED);

 
   /* If the start symbol isn't useful, then nothing will be useful. */
 
   /* If the start symbol isn't useful, then nothing will be useful. */

-  if (bitset_test (N, start_symbol - ntokens))
+  if (bitset_test (N, accept->number - ntokens))

     {
     {

-      bitset_set (V, start_symbol);
+      bitset_set (V, accept->number);

 
       while (1)
        {
 
       while (1)
        {

+         rule_number r;

          bitset_copy (Vp, V);
          bitset_copy (Vp, V);

-         for (i = 1; i <= nrules; i++)
+         for (r = 0; r < nrules; r++)

            {
            {

-             if (!bitset_test (Pp, i)
-                 && bitset_test (P, i)
-                 && bitset_test (V, rules[i].lhs))
+             if (!bitset_test (Pp, r)
+                 && bitset_test (P, r)
+                 && bitset_test (V, rules[r].lhs->number))

                {
                {

-                 for (r = &ritem[rules[i].rhs]; *r >= 0; r++)
-                   if (ISTOKEN (t = *r) || bitset_test (N, t - ntokens))
-                     bitset_set (Vp, t);
-                 bitset_set (Pp, i);
+                 item_number *rhsp;
+                 for (rhsp = rules[r].rhs; *rhsp >= 0; rhsp++)
+                   if (ISTOKEN (*rhsp) || bitset_test (N, *rhsp - ntokens))
+                     bitset_set (Vp, *rhsp);
+                 bitset_set (Pp, r);

                }
            }
          if (bitset_equal_p (V, Vp))
                }
            }
          if (bitset_equal_p (V, Vp))


@@ -198,9 +197,9 @@ inaccessable_symbols (void)
   V = Vp;
 
   /* Tokens 0, 1, and 2 are internal to Bison.  Consider them useful. */
   V = Vp;
 
   /* Tokens 0, 1, and 2 are internal to Bison.  Consider them useful. */

-  bitset_set (V, 0);           /* end-of-input token */
-  bitset_set (V, 1);           /* error token */
-  bitset_set (V, 2);           /* some undefined token */
+  bitset_set (V, endtoken->number);            /* end-of-input token */
+  bitset_set (V, errtoken->number);            /* error token */
+  bitset_set (V, undeftoken->number);          /* some undefined token */

 
   bitset_free (P);
   P = Pp;
 
   bitset_free (P);
   P = Pp;


@@ -209,81 +208,74 @@ inaccessable_symbols (void)
   nuseless_productions = nrules - nuseful_productions;
 
   nuseful_nonterminals = 0;
   nuseless_productions = nrules - nuseful_productions;
 
   nuseful_nonterminals = 0;

-  for (i = ntokens; i < nsyms; i++)
-    if (bitset_test (V, i))
-      nuseful_nonterminals++;
+  {
+    symbol_number i;
+    for (i = ntokens; i < nsyms; i++)
+      if (bitset_test (V, i))
+       nuseful_nonterminals++;
+  }

   nuseless_nonterminals = nvars - nuseful_nonterminals;
 
   /* A token that was used in %prec should not be warned about.  */
   nuseless_nonterminals = nvars - nuseful_nonterminals;
 
   /* A token that was used in %prec should not be warned about.  */

-  for (i = 1; i < nrules; i++)
-    if (rules[i].precsym != 0)
-      bitset_set (V1, rules[i].precsym);
+  {
+    rule_number r;
+    for (r = 0; r < nrules; ++r)
+      if (rules[r].precsym != 0)
+       bitset_set (V1, rules[r].precsym->number);
+  }

 }
 
 }
 

+
+/*-------------------------------------------------------------------.
+| Put the useless productions at the end of RULES, and adjust NRULES |
+| accordingly.                                                       |
+`-------------------------------------------------------------------*/
+

 static void
 reduce_grammar_tables (void)
 {
 static void
 reduce_grammar_tables (void)
 {

-  /* This is turned off because we would need to change the numbers in
-     the case statements in the actions file.
-
-     We don't disable it via CPP so that it is still checked with the
-     rest of the code, to avoid its becoming completely obsolete.
-
-     FIXME: I think the comment above demonstrates this code must be
-     turned off for *semantic* parser, not in the general case.  Try
-     to understand this better --akim.  */
+  /* Report and flag useless productions.  */
+  {
+    rule_number r;
+    for (r = 0; r < nrules; r++)
+      rules[r].useful = bitset_test (P, r);
+    grammar_rules_useless_report (_("rule useless in grammar"));
+  }

 
 

-  if (0)
-    /* remove useless productions */
-    if (nuseless_productions > 0)
+  /* Map the nonterminals to their new index: useful first, useless
+     afterwards.  Kept for later report.  */
+  {
+    int useful = 0;
+    int useless = nrules - nuseless_productions;
+    rule *rules_sorted = xnmalloc (nrules, sizeof *rules_sorted);
+    rule_number r;
+    for (r = 0; r < nrules; ++r)
+      rules_sorted[rules[r].useful ? useful++ : useless++] = rules[r];
+    free (rules);
+    rules = rules_sorted;
+
+    /* Renumber the rules markers in RITEMS.  */
+    for (r = 0; r < nrules; ++r)

       {
       {

-       short np, pn, ni, pi;
-
-       np = 0;
-       ni = 0;
-       for (pn = 1; pn <= nrules; pn++)
-         if (bitset_test (P, pn))
-           {
-             np++;
-             if (pn != np)
-               {
-                 rules[np].lhs   = rules[pn].lhs;
-                 rules[np].line  = rules[pn].line;
-                 rules[np].prec  = rules[pn].prec;
-                 rules[np].assoc = rules[pn].assoc;
-                 rules[np].rhs   = rules[pn].rhs;
-                 if (rules[np].rhs != ni)
-                   {
-                     pi = rules[np].rhs;
-                     rules[np].rhs = ni;
-                     while (ritem[pi] >= 0)
-                       ritem[ni++] = ritem[pi++];
-                     ritem[ni++] = -np;
-                   }
-               }
-             else
-               {
-                 while (ritem[ni++] >= 0)
-                   /* Nothing. */;
-               }
-           }
-
-       ritem[ni] = 0;
-       nrules -= nuseless_productions;
-       nitems = ni;
-       nritems = ni;
-
-       /* Is it worth it to reduce the amount of memory for the
-          grammar? Probably not.  */
+       item_number *rhsp = rules[r].rhs;
+       for (/* Nothing. */; *rhsp >= 0; ++rhsp)
+         /* Nothing. */;
+       *rhsp = rule_number_as_item_number (r);
+       rules[r].number = r;

       }
       }

+    nrules -= nuseless_productions;
+  }

 
 

-  /* Disable useless productions. */
-  if (nuseless_productions > 0)
-    {
-      int pn;
-      for (pn = 1; pn <= nrules; pn++)
-       rules[pn].useful = bitset_test (P, pn);
-    }
+  /* Adjust NRITEMS.  */
+  {
+    rule_number r;
+    int length;
+    for (r = nrules; r < nrules + nuseless_productions; ++r)
+      {
+       length = rule_rhs_length (&rules[r]);
+       nritems -= length + 1;
+      }
+  }

 }
 
 
 }
 
 


@@ -294,52 +286,55 @@ reduce_grammar_tables (void)
 static void
 nonterminals_reduce (void)
 {
 static void
 nonterminals_reduce (void)
 {

-  int i, n;
+  symbol_number i, n;

 
   /* Map the nonterminals to their new index: useful first, useless
      afterwards.  Kept for later report.  */
 
 
   /* Map the nonterminals to their new index: useful first, useless
      afterwards.  Kept for later report.  */
 

-  short *nontermmap = XCALLOC (short, nvars) - ntokens;
+  symbol_number *nontermmap = xnmalloc (nvars, sizeof *nontermmap);

   n = ntokens;
   for (i = ntokens; i < nsyms; i++)
     if (bitset_test (V, i))
   n = ntokens;
   for (i = ntokens; i < nsyms; i++)
     if (bitset_test (V, i))

-      nontermmap[i] = n++;
+      nontermmap[i - ntokens] = n++;

   for (i = ntokens; i < nsyms; i++)
     if (!bitset_test (V, i))
   for (i = ntokens; i < nsyms; i++)
     if (!bitset_test (V, i))

-      nontermmap[i] = n++;
+      {
+       nontermmap[i - ntokens] = n++;
+       warn_at (symbols[i]->location, _("nonterminal useless in grammar: %s"),
+                symbols[i]->tag);
+      }

 
 
   /* Shuffle elements of tables indexed by symbol number.  */
   {
 
 
   /* Shuffle elements of tables indexed by symbol number.  */
   {

-    bucket **symbols_sorted = XMALLOC (bucket *, nvars) - ntokens;
+    symbol **symbols_sorted = xnmalloc (nvars, sizeof *symbols_sorted);

 
     for (i = ntokens; i < nsyms; i++)
 
     for (i = ntokens; i < nsyms; i++)

-      symbols_sorted[nontermmap[i]] = symbols[i];
+      symbols[i]->number = nontermmap[i - ntokens];
+    for (i = ntokens; i < nsyms; i++)
+      symbols_sorted[nontermmap[i - ntokens] - ntokens] = symbols[i];

     for (i = ntokens; i < nsyms; i++)
     for (i = ntokens; i < nsyms; i++)

-      symbols[i] = symbols_sorted[i];
-    free (symbols_sorted + ntokens);
+      symbols[i] = symbols_sorted[i - ntokens];
+    free (symbols_sorted);

   }
 
   }
 

-  /* Replace all symbol numbers in valid data structures.  */
-
-  for (i = 1; i <= nrules; i++)
-    {
-      rules[i].lhs = nontermmap[rules[i].lhs];
-      if (ISVAR (rules[i].precsym))
-       /* Can this happen?  */
-       rules[i].precsym = nontermmap[rules[i].precsym];
-    }
-
-  for (i = 0; i < nritems; ++i)
-    if (ISVAR (ritem[i]))
-      ritem[i] = nontermmap[ritem[i]];
-
-  start_symbol = nontermmap[start_symbol];
+  {
+    rule_number r;
+    for (r = 0; r < nrules; ++r)
+      {
+       item_number *rhsp;
+       for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp)
+         if (ISVAR (*rhsp))
+           *rhsp =  symbol_number_as_item_number (nontermmap[*rhsp
+                                                             - ntokens]);
+      }
+    accept->number = nontermmap[accept->number - ntokens];
+  }

 
   nsyms -= nuseless_nonterminals;
   nvars -= nuseless_nonterminals;
 
 
   nsyms -= nuseless_nonterminals;
   nvars -= nuseless_nonterminals;
 

-  free (nontermmap + ntokens);
+  free (nontermmap);

 }
 
 
 }
 
 


@@ -353,21 +348,21 @@ reduce_output (FILE *out)
   if (nuseless_nonterminals > 0)
     {
       int i;
   if (nuseless_nonterminals > 0)
     {
       int i;

-      fprintf (out, "%s\n\n", _("Useless nonterminals:"));
+      fprintf (out, "%s\n\n", _("Nonterminals useless in grammar"));

       for (i = 0; i < nuseless_nonterminals; ++i)
        fprintf (out, "   %s\n", symbols[nsyms + i]->tag);
       fputs ("\n\n", out);
     }
 
   {
       for (i = 0; i < nuseless_nonterminals; ++i)
        fprintf (out, "   %s\n", symbols[nsyms + i]->tag);
       fputs ("\n\n", out);
     }
 
   {

-    bool b = FALSE;
+    bool b = false;

     int i;
     for (i = 0; i < ntokens; i++)
     int i;
     for (i = 0; i < ntokens; i++)

-      if (!bitset_test (V, i) && !bitset_test (V1, i))
+      if (reduce_token_unused_in_grammar (i))

        {
          if (!b)
        {
          if (!b)

-           fprintf (out, "%s\n\n", _("Terminals which are not used:"));
-         b = TRUE;
+           fprintf (out, "%s\n\n", _("Terminals unused in grammar"));
+         b = true;

          fprintf (out, "   %s\n", symbols[i]->tag);
        }
     if (b)
          fprintf (out, "   %s\n", symbols[i]->tag);
        }
     if (b)


@@ -375,71 +370,10 @@ reduce_output (FILE *out)
   }
 
   if (nuseless_productions > 0)
   }
 
   if (nuseless_productions > 0)

-    {
-      int i;
-      fprintf (out, "%s\n\n", _("Useless rules:"));
-      for (i = 1; i <= nrules; i++)
-       if (!rules[i].useful)
-         {
-           rule r;
-           fprintf (out, "#%-4d  ", i - 1);
-           fprintf (out, "%s:", symbols[rules[i].lhs]->tag);
-           for (r = &ritem[rules[i].rhs]; *r >= 0; r++)
-             fprintf (out, " %s", symbols[*r]->tag);
-           fputs (";\n", out);
-         }
-      fputs ("\n\n", out);
-    }
+    grammar_rules_partial_print (out, _("Rules useless in grammar"),
+                                rule_useless_in_grammar_p);

 }
 \f
 }
 \f

-static void
-dump_grammar (FILE *out)
-{
-  int i;
-  rule r;
-
-  fprintf (out, "REDUCED GRAMMAR\n\n");
-  fprintf (out,
-          "ntokens = %d, nvars = %d, nsyms = %d, nrules = %d, nitems = %d\n\n",
-          ntokens, nvars, nsyms, nrules, nitems);
-  fprintf (out, "Variables\n---------\n\n");
-  fprintf (out, "Value  Sprec  Sassoc  Tag\n");
-  for (i = ntokens; i < nsyms; i++)
-    fprintf (out, "%5d  %5d   %5d  %s\n",
-            i,
-            symbols[i]->prec, symbols[i]->assoc, symbols[i]->tag);
-  fprintf (out, "\n\n");
-  fprintf (out, "Rules\n-----\n\n");
-  fprintf (out, "Num (Prec, Assoc, Useful, Ritem Range) Lhs -> Rhs (Ritem range) [Num]\n");
-  for (i = 1; i <= nrules; i++)
-    {
-      int rhs_count = 0;
-      /* Find the last RHS index in ritems. */
-      for (r = &ritem[rules[i].rhs]; *r >= 0; ++r)
-       ++rhs_count;
-      fprintf (out, "%3d (%2d, %2d, %2d, %2d-%2d)   %2d ->",
-              i - 1,
-              rules[i].prec, rules[i].assoc, rules[i].useful,
-              rules[i].rhs, rules[i].rhs + rhs_count - 1,
-              rules[i].lhs);
-      /* Dumped the RHS. */
-      for (r = &ritem[rules[i].rhs]; *r >= 0; r++)
-       fprintf (out, "%3d", *r);
-      fprintf (out, "  [%d]\n", -(*r) - 1);
-    }
-  fprintf (out, "\n\n");
-  fprintf (out, "Rules interpreted\n-----------------\n\n");
-  for (i = 1; i <= nrules; i++)
-    {
-      fprintf (out, "%-5d  %s :", i, symbols[rules[i].lhs]->tag);
-      for (r = &ritem[rules[i].rhs]; *r >= 0; r++)
-       fprintf (out, " %s", symbols[*r]->tag);
-      fputc ('\n', out);
-    }
-  fprintf (out, "\n\n");
-}
-
-

 
 /*-------------------------------.
 | Report the results to STDERR.  |
 
 /*-------------------------------.
 | Report the results to STDERR.  |


@@ -448,30 +382,16 @@ dump_grammar (FILE *out)
 static void
 reduce_print (void)
 {
 static void
 reduce_print (void)
 {

-  if (yacc_flag && nuseless_productions)
-    fprintf (stderr, ngettext ("%d rule never reduced\n",
-                              "%d rules never reduced\n",
-                              nuseless_productions),
-            nuseless_productions);
-
-  fprintf (stderr, _("%s contains "), infile);
-

   if (nuseless_nonterminals > 0)
   if (nuseless_nonterminals > 0)

-    fprintf (stderr, ngettext ("%d useless nonterminal",
-                              "%d useless nonterminals",
-                              nuseless_nonterminals),
-            nuseless_nonterminals);
-
-  if (nuseless_nonterminals > 0 && nuseless_productions > 0)
-    fprintf (stderr, _(" and "));
-
+    warn (ngettext ("%d nonterminal useless in grammar",
+                    "%d nonterminals useless in grammar",
+                    nuseless_nonterminals),
+          nuseless_nonterminals);

   if (nuseless_productions > 0)
   if (nuseless_productions > 0)

-    fprintf (stderr, ngettext ("%d useless rule",
-                              "%d useless rules",
-                              nuseless_productions),
-            nuseless_productions);
-  fprintf (stderr, "\n");
-  fflush (stderr);
+    warn (ngettext ("%d rule useless in grammar",
+                    "%d rules useless in grammar",
+                    nuseless_productions),
+          nuseless_productions);

 }
 \f
 void
 }
 \f
 void


@@ -482,38 +402,55 @@ reduce_grammar (void)
   /* Allocate the global sets used to compute the reduced grammar */
 
   N = bitset_create (nvars, BITSET_FIXED);
   /* Allocate the global sets used to compute the reduced grammar */
 
   N = bitset_create (nvars, BITSET_FIXED);

-  P =  bitset_create (nrules + 1, BITSET_FIXED);
+  P =  bitset_create (nrules, BITSET_FIXED);

   V = bitset_create (nsyms, BITSET_FIXED);
   V1 = bitset_create (nsyms, BITSET_FIXED);
 
   useless_nonterminals ();
   inaccessable_symbols ();
 
   V = bitset_create (nsyms, BITSET_FIXED);
   V1 = bitset_create (nsyms, BITSET_FIXED);
 
   useless_nonterminals ();
   inaccessable_symbols ();
 

-  reduced = (bool) (nuseless_nonterminals + nuseless_productions > 0);
-
+  reduced = (nuseless_nonterminals + nuseless_productions > 0);

   if (!reduced)
     return;
 
   reduce_print ();
 
   if (!reduced)
     return;
 
   reduce_print ();
 

-  if (!bitset_test (N, start_symbol - ntokens))
-    fatal (_("Start symbol %s does not derive any sentence"),
-          symbols[start_symbol]->tag);
+  if (!bitset_test (N, accept->number - ntokens))
+    fatal_at (startsymbol_location,
+             _("start symbol %s does not derive any sentence"),
+             startsymbol->tag);

 
 

-  reduce_grammar_tables ();
+  /* First reduce the nonterminals, as they renumber themselves in the
+     whole grammar.  If you change the order, nonterms would be
+     renumbered only in the reduced grammar.  */

   if (nuseless_nonterminals > 0)
     nonterminals_reduce ();
   if (nuseless_nonterminals > 0)
     nonterminals_reduce ();

+  if (nuseless_productions > 0)
+    reduce_grammar_tables ();

 
 

-  if (trace_flag)
+  if (trace_flag & trace_grammar)

     {
     {

-      dump_grammar (stderr);
+      grammar_dump (stderr, "Reduced Grammar");

 
       fprintf (stderr, "reduced %s defines %d terminals, %d nonterminals\
 , and %d productions.\n",
 
       fprintf (stderr, "reduced %s defines %d terminals, %d nonterminals\
 , and %d productions.\n",

-              infile, ntokens, nvars, nrules);
+              grammar_file, ntokens, nvars, nrules);

     }
 }
 
     }
 }
 

+bool
+reduce_token_unused_in_grammar (symbol_number i)
+{
+  aver (i < ntokens);
+  return !bitset_test (V, i) && !bitset_test (V1, i);
+}
+
+bool
+reduce_nonterminal_useless_in_grammar (symbol_number i)
+{
+  aver (ntokens <= i && i < nsyms + nuseless_nonterminals);
+  return nsyms <= i;
+}

 
 /*-----------------------------------------------------------.
 | Free the global sets used to compute the reduced grammar.  |
 
 /*-----------------------------------------------------------.
 | Free the global sets used to compute the reduced grammar.  |