* src/gram.h, src/gram.c (rules_rhs_length): New.

(ritem_longest_rhs): Use it.
* src/gram.h (rule_t): `number' is a new member.
* src/reader.c (packgram): Set it.
* src/reduce.c (reduce_grammar_tables): Move the useless rules at
the end of `rules', and count them out of `nrules'.
(reduce_output, dump_grammar): Adjust.
* src/print.c (print_grammar): It is no longer needed to check for
the usefulness of a rule, as useless rules are beyond `nrules + 1'.
* tests/reduce.at (Reduced Automaton): New test.

ChangeLog

@@ -1,3 +1,16 @@
+2002-04-07  Akim Demaille  <akim@epita.fr>
+
+	* src/gram.h, src/gram.c (rules_rhs_length): New.
+	(ritem_longest_rhs): Use it.
+	* src/gram.h (rule_t): `number' is a new member.
+	* src/reader.c (packgram): Set it.
+	* src/reduce.c (reduce_grammar_tables): Move the useless rules at
+	the end of `rules', and count them out of `nrules'.
+	(reduce_output, dump_grammar): Adjust.
+	* src/print.c (print_grammar): It is no longer needed to check for
+	the usefulness of a rule, as useless rules are beyond `nrules + 1'.
+	* tests/reduce.at (Reduced Automaton): New test.
+
 2002-04-07  Akim Demaille  <akim@epita.fr>
 
 	* src/reduce.c (inaccessable_symbols): Fix a buglet: because of a

po/de.po

@@ -5,7 +5,7 @@
 msgid ""
 msgstr ""
 "Project-Id-Version: bison 1.25\n"
-"POT-Creation-Date: 2002-04-07 18:07+0200\n"
+"POT-Creation-Date: 2002-04-07 19:13+0200\n"
 "PO-Revision-Date: 1996-10-10 17:54 MET DST\n"
 "Last-Translator: Ulrich Drepper <drepper@gnu.ai.mit.edu>\n"
 "Language-Team: German <de@li.org>\n"

po/es.po

@@ -30,7 +30,7 @@
 msgid ""
 msgstr ""
 "Project-Id-Version: GNU bison 1.25\n"
-"POT-Creation-Date: 2002-04-07 18:07+0200\n"
+"POT-Creation-Date: 2002-04-07 19:13+0200\n"
 "PO-Revision-Date: 2002-03-14 19:34+0100\n"
 "Last-Translator: Nicolás García-Pedrajas <ngarcia-pedrajas@acm.org>\n"
 "Language-Team: Spanish <es@li.org>\n"

po/et.po

@@ -5,7 +5,7 @@
 msgid ""
 msgstr ""
 "Project-Id-Version: bison 1.28d\n"
-"POT-Creation-Date: 2002-04-07 18:07+0200\n"
+"POT-Creation-Date: 2002-04-07 19:13+0200\n"
 "PO-Revision-Date: 2001-08-29 17:06+02:00\n"
 "Last-Translator: Toomas Soome <tsoome@ut.ee>\n"
 "Language-Team: Estonian <et@li.org>\n"

po/fr.po

@@ -6,7 +6,7 @@
 msgid ""
 msgstr ""
 "Project-Id-Version: GNU bison 1.28d\n"
-"POT-Creation-Date: 2002-04-07 18:07+0200\n"
+"POT-Creation-Date: 2002-04-07 19:13+0200\n"
 "PO-Revision-Date: 2001-08-29 20:00-0500\n"
 "Last-Translator: Michel Robitaille <robitail@IRO.UMontreal.CA>\n"
 "Language-Team: French <traduc@traduc.org>\n"

po/it.po

@@ -5,7 +5,7 @@
 msgid ""
 msgstr ""
 "Project-Id-Version: bison 1.31\n"
-"POT-Creation-Date: 2002-04-07 18:07+0200\n"
+"POT-Creation-Date: 2002-04-07 19:13+0200\n"
 "PO-Revision-Date: 2002-01-18 12:40 CET\n"
 "Last-Translator: Paolo Bonzini <bonzini@gnu.org>\n"
 "Language-Team: Italian <it@li.org>\n"

po/ja.po

@@ -5,7 +5,7 @@
 msgid ""
 msgstr ""
 "Project-Id-Version: GNU bison 1.28\n"
-"POT-Creation-Date: 2002-04-07 18:07+0200\n"
+"POT-Creation-Date: 2002-04-07 19:13+0200\n"
 "PO-Revision-Date: 1999-09-28 21:10+0900\n"
 "Last-Translator: Daisuke Yamashita <yamad@mb.infoweb.ne.jp>\n"
 "Language-Team: Japanese <ja@li.org>\n"

po/nl.po

@@ -5,7 +5,7 @@
 msgid ""
 msgstr ""
 "Project-Id-Version: bison 1.25\n"
-"POT-Creation-Date: 2002-04-07 18:07+0200\n"
+"POT-Creation-Date: 2002-04-07 19:13+0200\n"
 "PO-Revision-Date: 1996-08-27 15:34 MET DST\n"
 "Last-Translator: Erick Branderhorst <branderh@debian.org>\n"
 "Language-Team: Dutch <nl@li.org>\n"

po/ru.po

@@ -5,7 +5,7 @@
 msgid ""
 msgstr ""
 "Project-Id-Version: bison 1.29\n"
-"POT-Creation-Date: 2002-04-07 18:07+0200\n"
+"POT-Creation-Date: 2002-04-07 19:13+0200\n"
 "PO-Revision-Date: 2001-09-09 13:49+04:00\n"
 "Last-Translator: Dmitry S. Sivachenko <dima@Chg.RU>\n"
 "Language-Team: Russian <ru@li.org>\n"

po/sv.po

@@ -6,7 +6,7 @@
 msgid ""
 msgstr ""
 "Project-Id-Version: bison 1.30c\n"
-"POT-Creation-Date: 2002-04-07 18:07+0200\n"
+"POT-Creation-Date: 2002-04-07 19:13+0200\n"
 "PO-Revision-Date: 2001-11-18 15:17+0100\n"
 "Last-Translator: Göran Uddeborg <goeran@uddeborg.pp.se>\n"
 "Language-Team: Swedish <sv@li.org>\n"

po/tr.po

@@ -5,7 +5,7 @@
 msgid ""
 msgstr ""
 "Project-Id-Version: bison 1.28c\n"
-"POT-Creation-Date: 2002-04-07 18:07+0200\n"
+"POT-Creation-Date: 2002-04-07 19:13+0200\n"
 "PO-Revision-Date: 2001-09-10 10:54GMT\n"
 "Last-Translator: Altug Bayram <altugbayram_2000@yahoo.com>\n"
 "Language-Team: Turkish <gnu-tr-u12a@lists.sourceforge.net>\n"

src/gram.c

@@ -1,5 +1,5 @@
 /* Allocate input grammar variables for bison,
-   Copyright 1984, 1986, 1989, 2001 Free Software Foundation, Inc.
+   Copyright 1984, 1986, 1989, 2001, 2002 Free Software Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
@@ -51,6 +51,21 @@ int pure_parser;
 int error_token_number;
 
 
+/*--------------------------------------.
+| Return the number of symbols in RHS.  |
+`--------------------------------------*/
+
+int
+rule_rhs_length (rule_t *rule)
+{
+  int res = 0;
+  short *rhsp;
+  for (rhsp = rule->rhs; *rhsp >= 0; ++rhsp)
+    ++res;
+  return res;
+}
+
+
 /*------------------------.
 | Dump RITEM for traces.  |
 `------------------------*/
@@ -76,23 +91,15 @@ ritem_print (FILE *out)
 size_t
 ritem_longest_rhs (void)
 {
-  int length;
+  int max = 0;
-  int max;
   int i;
 
-  length = 0;
+  for (i = 1; i < nrules + 1; ++i)
-  max = 0;
+    {
-  for (i = 0; i < nritems; ++i)
+      int length = rule_rhs_length (&rules[i]);
-    if (ritem[i] >= 0)
+      if (length > max)
-      {
+	max = length;
-	length++;
+    }
-      }
-    else
-      {
-	if (length > max)
-	  max = length;
-	length = 0;
-      }
 
   return max;
 }

src/gram.h

@@ -124,6 +124,10 @@ typedef enum
 
 typedef struct rule_s
 {
+  /* The number of the rule in the source.  It is usually the index in
+     RULES too, except if there are useless rules.  */
+  short number;
+
   short lhs;
   short *rhs;
   short prec;
@@ -166,6 +170,8 @@ extern int pure_parser;
 
 extern int error_token_number;
 
+/* Report the length of the RHS. */
+int rule_rhs_length PARAMS ((rule_t *rule));
 
 /* Dump RITEM for traces. */
 void ritem_print PARAMS ((FILE *out));

src/print.c

@@ -366,19 +366,17 @@ print_grammar (FILE *out)
   fprintf (out, "%s\n\n", _("Grammar"));
   fprintf (out, "  %s\n", _("Number, Line, Rule"));
   for (i = 1; i < nrules + 1; i++)
-    /* Don't print rules disabled in reduce_grammar_tables.  */
+    {
-    if (rules[i].useful)
+      fprintf (out, _("  %3d %3d %s ->"),
-      {
+	       i - 1, rules[i].line, escape (symbols[rules[i].lhs]->tag));
-	fprintf (out, _("  %3d %3d %s ->"),
+      rule = rules[i].rhs;
-		 i - 1, rules[i].line, escape (symbols[rules[i].lhs]->tag));
+      if (*rule >= 0)
-	rule = rules[i].rhs;
+	while (*rule >= 0)
-	if (*rule >= 0)
+	  fprintf (out, " %s", escape (symbols[*rule++]->tag));
-	  while (*rule >= 0)
+      else
-	    fprintf (out, " %s", escape (symbols[*rule++]->tag));
+	fprintf (out, " /* %s */", _("empty"));
-	else
+      fputc ('\n', out);
-	  fprintf (out, " /* %s */", _("empty"));
+    }
-	fputc ('\n', out);
-      }
   fputs ("\n\n", out);
 
 

src/reader.c

@@ -1687,6 +1687,7 @@ packgram (void)
   while (p)
     {
       bucket *ruleprec = p->ruleprec;
+      rules[ruleno].number = ruleno;
       rules[ruleno].lhs = p->sym->number;
       rules[ruleno].rhs = ritem + itemno;
       rules[ruleno].line = p->line;

src/reduce.c

@@ -220,70 +220,64 @@ inaccessable_symbols (void)
       bitset_set (V1, rules[i].precsym);
 }
 
+
+/*-------------------------------------------------------------------.
+| Put the useless productions at the end of RULES, and adjust NRULES |
+| accordingly.                                                       |
+`-------------------------------------------------------------------*/
+
 static void
 reduce_grammar_tables (void)
 {
-  /* This is turned off because we would need to change the numbers in
+  /* Flag useless productions.  */
-     the case statements in the actions file.
+  {
+    int pn;
+    for (pn = 1; pn < nrules + 1; pn++)
+      rules[pn].useful = bitset_test (P, pn);
+  }
 
-     We don't disable it via CPP so that it is still checked with the
+  /* Map the nonterminals to their new index: useful first, useless
-     rest of the code, to avoid its becoming completely obsolete.
+     afterwards.  Kept for later report.  */
+  {
+    int useful = 1;
+    int useless = nrules + 1 - nuseless_productions;
+    rule_t *rules_sorted = XMALLOC (rule_t, nrules + 1) - 1;
+    int i;
+    for (i = 1; i < nrules + 1; ++i)
+      rules_sorted[rules[i].useful ? useful++ : useless++] = rules[i];
+    free (rules + 1);
+    rules = rules_sorted;
 
-     FIXME: I think the comment above demonstrates this code must be
+    /* Also reorder ritems. */
-     turned off for *semantic* parser, not in the general case.  Try
-     to understand this better --akim.  */
-
-  if (0)
-    /* remove useless productions */
-    if (nuseless_productions > 0)
-      {
-	short np, pn, ni, pi;
-
-	np = 0;
-	ni = 0;
-	for (pn = 1; pn < nrules + 1; 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 - ritem != ni)
-		    {
-		      pi = rules[np].rhs - ritem;
-		      rules[np].rhs = ritem + 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.  */
-      }
-
-  /* Disable useless productions. */
-  if (nuseless_productions > 0)
     {
-      int pn;
+      short *ritems_sorted = XCALLOC (short, nitems + 1);
-      for (pn = 1; pn < nrules + 1; pn++)
+      short *ritemsp = ritems_sorted;
-	rules[pn].useful = bitset_test (P, pn);
+      for (i = 1; i < nrules + 1; ++i)
+	{
+	  short *rhsp = rules[i].rhs;
+	  rules[i].rhs = ritemsp;
+	  for (/* Nothing. */; *rhsp >= 0; ++rhsp)
+	    *ritemsp++ = *rhsp;
+	  *ritemsp++ = -i;
+	}
+      *ritemsp++ = 0;
+      free (ritem);
+      ritem = ritems_sorted;
     }
+    nrules -= nuseless_productions;
+  }
+
+  /* Adjust NRITEMS and NITEMS.  */
+  {
+    int r;
+    int length;
+    for (r = nrules + 1; r < nrules + 1 + nuseless_productions; ++r)
+      {
+	length = rule_rhs_length (&rules[r]);
+	nritems -= length + 1;
+	nitems -= length + 1;
+      }
+  }
 }
 
 
@@ -378,16 +372,15 @@ reduce_output (FILE *out)
     {
       int i;
       fprintf (out, "%s\n\n", _("Useless rules:"));
-      for (i = 1; i < nrules + 1; i++)
+      for (i = nrules + 1; i < nuseless_productions + nrules + 1; i++)
-	if (!rules[i].useful)
+	{
-	  {
+	  rule r;
-	    rule r;
+	  fprintf (out, "#%-4d  ", rules[i].number - 1);
-	    fprintf (out, "#%-4d  ", i - 1);
+	  fprintf (out, "%s:", symbols[rules[i].lhs]->tag);
-	    fprintf (out, "%s:", symbols[rules[i].lhs]->tag);
+	  for (r = rules[i].rhs; *r >= 0; r++)
-	    for (r = rules[i].rhs; *r >= 0; r++)
+	    fprintf (out, " %s", symbols[*r]->tag);
-	      fprintf (out, " %s", symbols[*r]->tag);
+	  fputs (";\n", out);
-	    fputs (";\n", out);
+	}
-	  }
       fputs ("\n\n", out);
     }
 }
@@ -411,7 +404,7 @@ dump_grammar (FILE *out)
   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 + 1; i++)
+  for (i = 1; i < nrules + nuseless_productions + 1; i++)
     {
       int rhs_count = 0;
       /* Find the last RHS index in ritems. */
@@ -429,7 +422,7 @@ dump_grammar (FILE *out)
     }
   fprintf (out, "\n\n");
   fprintf (out, "Rules interpreted\n-----------------\n\n");
-  for (i = 1; i < nrules + 1; i++)
+  for (i = 1; i < nrules + nuseless_productions + 1; i++)
     {
       fprintf (out, "%-5d  %s :", i, symbols[rules[i].lhs]->tag);
       for (r = rules[i].rhs; *r >= 0; r++)
@@ -499,7 +492,8 @@ reduce_grammar (void)
     fatal (_("Start symbol %s does not derive any sentence"),
 	   symbols[start_symbol]->tag);
 
-  reduce_grammar_tables ();
+  if (nuseless_productions > 0)
+    reduce_grammar_tables ();
   if (nuseless_nonterminals > 0)
     nonterminals_reduce ();
 

tests/reduce.at

@@ -173,6 +173,89 @@ AT_CLEANUP
 
 
 
+## ------------------- ##
+## Reduced Automaton.  ##
+## ------------------- ##
+
+# Check that the automaton is that as the for the grammar reduced by
+# hand.
+
+AT_SETUP([Reduced Automaton])
+
+# The non reduced grammar.
+# ------------------------
+AT_DATA([[not-reduced.y]],
+[[/* A useless token. */
+%token useless_token
+/* A useful one. */
+%token useful
+%verbose
+%output="not-reduced.c"
+
+%%
+
+exp: useful            { /* A useful action. */ }
+   | non_productive    { /* A non productive action. */ }
+   ;
+
+not_reachable: useful  { /* A not reachable action. */ }
+             ;
+
+non_productive: non_productive useless_token
+                       { /* Another non productive action. */ }
+              ;
+]])
+
+AT_CHECK([[bison not-reduced.y]], 0, [],
+[[not-reduced.y contains 2 useless nonterminals and 3 useless rules
+]])
+
+AT_CHECK([[sed -n '/^Grammar/q;/^$/!p' not-reduced.output]], 0,
+[[Useless nonterminals:
+   not_reachable
+   non_productive
+Terminals which are not used:
+   useless_token
+Useless rules:
+#2     exp: non_productive;
+#3     not_reachable: useful;
+#4     non_productive: non_productive useless_token;
+]])
+
+# The reduced grammar.
+# --------------------
+AT_DATA([[reduced.y]],
+[[/* A useless token. */
+%token useless_token
+/* A useful one. */
+%token useful
+%verbose
+%output="reduced.c"
+
+%%
+
+exp: useful            { /* A useful action. */ }
+//   | non_productive    { /* A non productive action. */ } */
+   ;
+
+//not_reachable: useful  { /* A not reachable action. */ }
+//             ;
+
+//non_productive: non_productive useless_token
+//                       { /* Another non productive action. */ }
+//              ;
+]])
+
+AT_CHECK([[bison reduced.y]])
+
+# Comparing the parsers.
+cp reduced.c expout
+AT_CHECK([sed 's/not-reduced/reduced/g' not-reduced.c], 0, [expout])
+
+AT_CLEANUP
+
+
+
 ## ------------------- ##
 ## Underivable Rules.  ##
 ## ------------------- ##