X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/bba97eb2c13a632c9a23306a834de312df16e4e0..3c5362b825a9d01eafe257943b7faad92ea43a05:/src/reduce.c

diff --git a/src/reduce.c b/src/reduce.c
index db033b34..67e72a36 100644
--- a/src/reduce.c
+++ b/src/reduce.c
@@ -1,22 +1,22 @@
 /* Grammar reduction for Bison.
-   Copyright 1988, 1989, 2000, 2001  Free Software Foundation, Inc.
+
+   Copyright (C) 1988, 1989, 2000, 2001, 2002, 2003, 2005, 2006, 2007,
+   2008-2009 Free Software Foundation, Inc.
 
    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
-   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
-   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,
@@ -25,19 +25,20 @@
 /* Don't eliminate unreachable terminals: They may be used by the
    user's parser.  */
 
+#include <config.h>
 #include "system.h"
-#include "getargs.h"
+
+#include <bitset.h>
+#include <quotearg.h>
+
+#include "complain.h"
 #include "files.h"
-#include "symtab.h"
+#include "getargs.h"
 #include "gram.h"
-#include "complain.h"
-#include "reduce.h"
+#include "print-xml.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;
@@ -52,10 +53,10 @@ static bitset V;
    `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;
-int nuseless_nonterminals;
+symbol_number nuseless_nonterminals;
 
 /*-------------------------------------------------------------------.
 | Another way to do this would be with a set for each production and |
@@ -64,18 +65,17 @@ int nuseless_nonterminals;
 `-------------------------------------------------------------------*/
 
 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.  */
 
-  for (r = 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;
-  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.  */
@@ -114,12 +114,12 @@ useless_nonterminals (void)
   while (1)
     {
       bitset_copy (Np, N);
-      for (i = 1; i < nrules + 1; 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->number - ntokens);
-	    bitset_set (P, i);
+	    bitset_set (Np, rules[r].lhs->number - ntokens);
+	    bitset_set (P, r);
 	  }
       if (bitset_equal_p (N, Np))
 	break;
@@ -136,9 +136,6 @@ static void
 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
@@ -164,26 +161,28 @@ inaccessable_symbols (void)
      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 (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)
 	{
+	  rule_number r;
 	  bitset_copy (Vp, V);
-	  for (i = 1; i < nrules + 1; i++)
+	  for (r = 0; r < nrules; r++)
 	    {
-	      if (!bitset_test (Pp, i)
-		  && bitset_test (P, i)
-		  && bitset_test (V, rules[i].lhs->number))
+	      if (!bitset_test (Pp, r)
+		  && bitset_test (P, r)
+		  && bitset_test (V, rules[r].lhs->number))
 		{
-		  for (r = 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))
@@ -198,9 +197,9 @@ inaccessable_symbols (void)
   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;
@@ -209,15 +208,21 @@ inaccessable_symbols (void)
   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.  */
-  for (i = 1; i < nrules + 1; 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);
+  }
 }
 
 
@@ -229,53 +234,46 @@ inaccessable_symbols (void)
 static void
 reduce_grammar_tables (void)
 {
-  /* Flag useless productions.  */
+  /* Report and flag useless productions.  */
   {
-    int pn;
-    for (pn = 1; pn < nrules + 1; pn++)
-      rules[pn].useful = bitset_test (P, pn);
+    rule_number r;
+    for (r = 0; r < nrules; r++)
+      rules[r].useful = bitset_test (P, r);
+    grammar_rules_useless_report (_("rule useless in grammar"));
   }
 
   /* Map the nonterminals to their new index: useful first, useless
      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);
+    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;
 
-    /* Also reorder ritems. */
-    {
-      short *ritems_sorted = XCALLOC (short, nitems + 1);
-      short *ritemsp = ritems_sorted;
-      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;
-    }
+    /* Renumber the rules markers in RITEMS.  */
+    for (r = 0; r < nrules; ++r)
+      {
+	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;
   }
 
-  /* Adjust NRITEMS and NITEMS.  */
+  /* Adjust NRITEMS.  */
   {
-    int r;
+    rule_number r;
     int length;
-    for (r = nrules + 1; r < nrules + 1 + nuseless_productions; ++r)
+    for (r = nrules; r < nrules + nuseless_productions; ++r)
       {
 	length = rule_rhs_length (&rules[r]);
 	nritems -= length + 1;
-	nitems -= length + 1;
       }
   }
 }
@@ -288,53 +286,55 @@ reduce_grammar_tables (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.  */
 
-  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))
-      nontermmap[i] = n++;
+      nontermmap[i - ntokens] = n++;
   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.  */
   {
-    bucket **symbols_sorted = XMALLOC (bucket *, nvars) - ntokens;
+    symbol **symbols_sorted = xnmalloc (nvars, sizeof *symbols_sorted);
 
     for (i = ntokens; i < nsyms; i++)
-      symbols[i]->number = nontermmap[i];
+      symbols[i]->number = nontermmap[i - ntokens];
     for (i = ntokens; i < nsyms; i++)
-      symbols_sorted[nontermmap[i]] = symbols[i];
+      symbols_sorted[nontermmap[i - ntokens] - ntokens] = symbols[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 + 1; i++)
-    {
-      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;
 
-  free (nontermmap + ntokens);
+  free (nontermmap);
 }
 
 
@@ -348,21 +348,21 @@ reduce_output (FILE *out)
   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);
     }
 
   {
-    bool b = FALSE;
+    bool b = false;
     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)
-	    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)
@@ -370,70 +370,10 @@ reduce_output (FILE *out)
   }
 
   if (nuseless_productions > 0)
-    {
-      int i;
-      fprintf (out, "%s\n\n", _("Useless rules:"));
-      for (i = nrules + 1; i < nuseless_productions + nrules + 1; i++)
-	{
-	  rule r;
-	  fprintf (out, "#%-4d  ", rules[i].number - 1);
-	  fprintf (out, "%s:", rules[i].lhs->tag);
-	  for (r = 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);
 }
 
-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 + nuseless_productions + 1; i++)
-    {
-      int rhs_count = 0;
-      /* Find the last RHS index in ritems. */
-      for (r = 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 - ritem, rules[i].rhs - ritem + rhs_count - 1,
-	       rules[i].lhs->number);
-      /* Dumped the RHS. */
-      for (r = 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 + nuseless_productions + 1; i++)
-    {
-      fprintf (out, "%-5d  %s :", i, rules[i].lhs->tag);
-      for (r = rules[i].rhs; *r >= 0; r++)
-	fprintf (out, " %s", symbols[*r]->tag);
-      fputc ('\n', out);
-    }
-  fprintf (out, "\n\n");
-}
-
-
 
 /*-------------------------------.
 | Report the results to STDERR.  |
@@ -442,30 +382,24 @@ dump_grammar (FILE *out)
 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)
-    fprintf (stderr, ngettext ("%d useless nonterminal",
-			       "%d useless nonterminals",
-			       nuseless_nonterminals),
-	     nuseless_nonterminals);
-
-  if (nuseless_nonterminals > 0 && nuseless_productions > 0)
-    fprintf (stderr, _(" and "));
-
+    {
+      fprintf (stderr, "%s: %s: ", grammar_file, _("warning"));
+      fprintf (stderr, ngettext ("%d nonterminal useless in grammar",
+                                 "%d nonterminals useless in grammar",
+                                 nuseless_nonterminals),
+               nuseless_nonterminals);
+      fprintf (stderr, "\n");
+    }
   if (nuseless_productions > 0)
-    fprintf (stderr, ngettext ("%d useless rule",
-			       "%d useless rules",
-			       nuseless_productions),
-	     nuseless_productions);
-  fprintf (stderr, "\n");
-  fflush (stderr);
+    {
+      fprintf (stderr, "%s: %s: ", grammar_file, _("warning"));
+      fprintf (stderr, ngettext ("%d rule useless in grammar",
+                                 "%d rules useless in grammar",
+                                 nuseless_productions),
+               nuseless_productions);
+      fprintf (stderr, "\n");
+    }
 }
 
 void
@@ -476,38 +410,55 @@ reduce_grammar (void)
   /* 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 ();
 
-  reduced = (bool) (nuseless_nonterminals + nuseless_productions > 0);
+  reduced = (nuseless_nonterminals + nuseless_productions > 0);
   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);
 
-  if (nuseless_productions > 0)
-    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_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",
-	       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.  |