X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/2c5f66eda72bb8b158bccf0a528d9dbb2c839f0c..3d4daee37491bab92ce270b37b257aadcf709c3c:/src/reduce.c

diff --git a/src/reduce.c b/src/reduce.c
index b179f608..430e5b08 100644
--- a/src/reduce.c
+++ b/src/reduce.c
@@ -38,16 +38,23 @@ typedef unsigned *BSet;
 typedef short *rule;
 
 
-/* N is set of all nonterminals which are not useless.  P is set of
-   all rules which have no useless nonterminals in their RHS.  V is
-   the set of all accessible symbols.  */
+/* Set of all nonterminals which are not useless.  */
+static BSet N;
 
-static BSet N, P, V, V1;
+/* Set of all rules which have no useless nonterminals in their RHS.  */
+static BSet P;
+
+/* Set of all accessible symbols.  */
+static BSet V;
+
+/* Set of symbols used to define rule precedence (so they are
+   `useless', but no warning should be issued).  */
+static BSet V1;
 
 static int nuseful_productions;
 static int nuseless_productions;
 static int nuseful_nonterminals;
-static int nuseless_nonterminals;
+int nuseless_nonterminals;
 
 static bool
 bits_equal (BSet L, BSet R, int n)
@@ -100,7 +107,7 @@ useful_production (int i, BSet N0)
   /* A production is useful if all of the nonterminals in its appear
      in the set of useful nonterminals.  */
 
-  for (r = &ritem[rule_table[i].rhs]; *r > 0; r++)
+  for (r = &ritem[rule_table[i].rhs]; *r >= 0; r++)
     if (ISVAR (n = *r))
       if (!BITISSET (N0, n - ntokens))
 	return FALSE;
@@ -257,28 +264,35 @@ inaccessable_symbols (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.  */
-#if 0
-  /* remove useless productions */
-  if (nuseless_productions > 0)
-    {
-      short np, pn, ni, pi;
+  /* This is turned off because we would need to change the numbers in
+     the case statements in the actions file.
 
-      np = 0;
-      ni = 0;
-      for (pn = 1; pn <= nrules; pn++)
-	{
+     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.  */
+
+  if (0)
+    /* remove useless productions */
+    if (nuseless_productions > 0)
+      {
+	short np, pn, ni, pi;
+
+	np = 0;
+	ni = 0;
+	for (pn = 1; pn <= nrules; pn++)
 	  if (BITISSET (P, pn))
 	    {
 	      np++;
 	      if (pn != np)
 		{
-		  rule_table[np].lhs = rule_table[pn].lhs;
-		  rline[np] = rline[pn];
-		  rule_table[np].prec = rule_table[pn].prec;
+		  rule_table[np].lhs   = rule_table[pn].lhs;
+		  rule_table[np].line  = rule_table[pn].line;
+		  rule_table[np].prec  = rule_table[pn].prec;
 		  rule_table[np].assoc = rule_table[pn].assoc;
-		  rule_table[np].rhs = rule_table[pn].rhs;
+		  rule_table[np].rhs   = rule_table[pn].rhs;
 		  if (rule_table[np].rhs != ni)
 		    {
 		      pi = rule_table[np].rhs;
@@ -290,155 +304,149 @@ reduce_grammar_tables (void)
 		}
 	      else
 		{
-		  while (ritem[ni++] >= 0);
+		  while (ritem[ni++] >= 0)
+		    /* Nothing. */;
 		}
 	    }
-	}
-      ritem[ni] = 0;
-      nrules -= nuseless_productions;
-      nitems = ni;
 
-      /* Is it worth it to reduce the amount of memory for the
-         grammar? Probably not.  */
+	ritem[ni] = 0;
+	nrules -= nuseless_productions;
+	nitems = ni;
+	nritems = ni;
 
-    }
-#endif /* 0 */
-  /* Disable useless productions,
-     since they may contain useless nonterms
-     that would get mapped below to -1 and confuse everyone.  */
+	/* Is it worth it to reduce the amount of memory for the
+	   grammar? Probably not.  */
+      }
+
+  /* Disable useless productions. */
   if (nuseless_productions > 0)
     {
       int pn;
-
       for (pn = 1; pn <= nrules; pn++)
-	{
-	  if (!BITISSET (P, pn))
-	    {
-	      rule_table[pn].lhs = -1;
-	    }
-	}
+	rule_table[pn].useful = BITISSET (P, pn);
     }
+}
 
-  /* remove useless symbols */
-  if (nuseless_nonterminals > 0)
-    {
-
-      int i, n;
-/*      short  j; JF unused */
-      short *nontermmap;
-      rule r;
-
-      /* Create a map of nonterminal number to new nonterminal
-	 number. -1 in the map means it was useless and is being
-	 eliminated.  */
 
-      nontermmap = XCALLOC (short, nvars) - ntokens;
-      for (i = ntokens; i < nsyms; i++)
-	nontermmap[i] = -1;
+/*------------------------------.
+| Remove useless nonterminals.  |
+`------------------------------*/
 
-      n = ntokens;
-      for (i = ntokens; i < nsyms; i++)
-	if (BITISSET (V, i))
-	  nontermmap[i] = n++;
+static void
+nonterminals_reduce (void)
+{
+  int i, n;
+  rule r;
 
-      /* Shuffle elements of tables indexed by symbol number.  */
+  /* Map the nonterminals to their new index: useful first, useless
+     afterwards.  Kept for later report.  */
 
-      for (i = ntokens; i < nsyms; i++)
-	{
-	  n = nontermmap[i];
-	  if (n >= 0)
-	    {
-	      sassoc[n] = sassoc[i];
-	      sprec[n] = sprec[i];
-	      tags[n] = tags[i];
-	    }
-	  else
-	    {
-	      free (tags[i]);
-	    }
-	}
-
-      /* Replace all symbol numbers in valid data structures.  */
+  short *nontermmap = XCALLOC (short, nvars) - ntokens;
+  n = ntokens;
+  for (i = ntokens; i < nsyms; i++)
+    if (BITISSET (V, i))
+      nontermmap[i] = n++;
+  for (i = ntokens; i < nsyms; i++)
+    if (!BITISSET (V, i))
+      nontermmap[i] = n++;
+
+
+  /* Shuffle elements of tables indexed by symbol number.  */
+  {
+    short *sassoc_sorted = XMALLOC (short, nvars) - ntokens;
+    short *sprec_sorted  = XMALLOC (short, nvars) - ntokens;
+    char **tags_sorted   = XMALLOC (char *, nvars) - ntokens;
+
+    for (i = ntokens; i < nsyms; i++)
+      {
+	n = nontermmap[i];
+	sassoc_sorted[n] = sassoc[i];
+	sprec_sorted[n]  = sprec[i];
+	tags_sorted[n]   = tags[i];
+      }
+    for (i = ntokens; i < nsyms; i++)
+      {
+	sassoc[i] = sassoc_sorted[i];
+	sprec[i]  = sprec_sorted[i];
+	tags[i]   = tags_sorted[i];
+      }
+    free (sassoc_sorted + ntokens);
+    free (sprec_sorted + ntokens);
+    free (tags_sorted + ntokens);
+  }
+
+  /* Replace all symbol numbers in valid data structures.  */
 
-      for (i = 1; i <= nrules; i++)
-	{
-	  /* Ignore the rules disabled above.  */
-	  if (rule_table[i].lhs >= 0)
-	    rule_table[i].lhs = nontermmap[rule_table[i].lhs];
-	  if (ISVAR (rule_table[i].precsym))
-	    /* Can this happen?  */
-	    rule_table[i].precsym = nontermmap[rule_table[i].precsym];
-	}
+  for (i = 1; i <= nrules; i++)
+    {
+      rule_table[i].lhs = nontermmap[rule_table[i].lhs];
+      if (ISVAR (rule_table[i].precsym))
+	/* Can this happen?  */
+	rule_table[i].precsym = nontermmap[rule_table[i].precsym];
+    }
 
-      for (r = ritem; *r; r++)
-	if (ISVAR (*r))
-	  *r = nontermmap[*r];
+  for (i = 0; i < nritems; ++i)
+    if (ISVAR (ritem[i]))
+      ritem[i] = nontermmap[ritem[i]];
 
-      start_symbol = nontermmap[start_symbol];
+  start_symbol = nontermmap[start_symbol];
 
-      nsyms -= nuseless_nonterminals;
-      nvars -= nuseless_nonterminals;
+  nsyms -= nuseless_nonterminals;
+  nvars -= nuseless_nonterminals;
 
-      free (&nontermmap[ntokens]);
-    }
+  free (nontermmap + ntokens);
 }
 
 
-/*-----------------------------------------------------------------.
-| Ouput the detailed results of the reductions.  For FILE.output.  |
-`-----------------------------------------------------------------*/
+/*------------------------------------------------------------------.
+| Output the detailed results of the reductions.  For FILE.output.  |
+`------------------------------------------------------------------*/
 
 void
 reduce_output (FILE *out)
 {
-  int i;
-  rule r;
-  bool b;
-
   if (nuseless_nonterminals > 0)
     {
-      fprintf (out, _("Useless nonterminals:"));
-      fprintf (out, "\n\n");
-      for (i = ntokens; i < nsyms; i++)
-	if (!BITISSET (V, i))
-	  fprintf (out, "   %s\n", tags[i]);
+      int i;
+      fprintf (out, "%s\n\n", _("Useless nonterminals:"));
+      for (i = 0; i < nuseless_nonterminals; ++i)
+	fprintf (out, "   %s\n", tags[nsyms + i]);
+      fputs ("\n\n", out);
     }
-  b = FALSE;
-  for (i = 0; i < ntokens; i++)
-    {
+
+  {
+    bool b = FALSE;
+    int i;
+    for (i = 0; i < ntokens; i++)
       if (!BITISSET (V, i) && !BITISSET (V1, i))
 	{
 	  if (!b)
-	    {
-	      fprintf (out, "\n\n");
-	      fprintf (out, _("Terminals which are not used:"));
-	      fprintf (out, "\n\n");
-	      b = TRUE;
-	    }
+	    fprintf (out, "%s\n\n", _("Terminals which are not used:"));
+	  b = TRUE;
 	  fprintf (out, "   %s\n", tags[i]);
 	}
-    }
+    if (b)
+      fputs ("\n\n", out);
+  }
 
   if (nuseless_productions > 0)
     {
-      fprintf (out, "\n\n");
-      fprintf (out, _("Useless rules:"));
-      fprintf (out, "\n\n");
+      int i;
+      fprintf (out, "%s\n\n", _("Useless rules:"));
       for (i = 1; i <= nrules; i++)
-	if (!BITISSET (P, i))
+	if (!rule_table[i].useful)
 	  {
-	    fprintf (out, "#%-4d  ", i);
-	    fprintf (out, "%s :\t", tags[rule_table[i].lhs]);
+	    rule r;
+	    fprintf (out, "#%-4d  ", i - 1);
+	    fprintf (out, "%s:", tags[rule_table[i].lhs]);
 	    for (r = &ritem[rule_table[i].rhs]; *r >= 0; r++)
 	      fprintf (out, " %s", tags[*r]);
-	    fprintf (out, ";\n");
+	    fputs (";\n", out);
 	  }
+      fputs ("\n\n", out);
     }
-  if (nuseless_nonterminals > 0 || nuseless_productions > 0 || b)
-    fprintf (out, "\n\n");
 }
 
-#if TRACE
 static void
 dump_grammar (FILE *out)
 {
@@ -447,38 +455,42 @@ dump_grammar (FILE *out)
 
   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"));
+	   "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, sprec[i], sassoc[i], tags[i]);
+    fprintf (out, "%5d  %5d   %5d  %s\n", i, sprec[i], sassoc[i], tags[i]);
   fprintf (out, "\n\n");
-  fprintf (out, _("Rules\n-----\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++)
     {
-      fprintf (out, "%-5d(%5d%5d)%5d : (@%-5d)",
-	       i,
-	       rule_table[i].prec,
-	       rule_table[i].assoc,
-	       rule_table[i].lhs,
-	       rule_table[i].rhs);
-      for (r = &ritem[rule_table[i].rhs]; *r > 0; r++)
-	fprintf (out, "%5d", *r);
-      fprintf (out, " [%d]\n", -(*r));
+      int rhs_count = 0;
+      /* Find the last RHS index in ritems. */
+      for (r = &ritem[rule_table[i].rhs]; *r >= 0; ++r)
+	++rhs_count;
+      fprintf (out, "%3d (%2d, %2d, %2d, %2d-%2d)   %2d ->",
+	       i - 1,
+	       rule_table[i].prec, rule_table[i].assoc, rule_table[i].useful,
+	       rule_table[i].rhs, rule_table[i].rhs + rhs_count - 1,
+	       rule_table[i].lhs);
+      /* Dumped the RHS. */
+      for (r = &ritem[rule_table[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"));
+  fprintf (out, "Rules interpreted\n-----------------\n\n");
   for (i = 1; i <= nrules; i++)
     {
       fprintf (out, "%-5d  %s :", i, tags[rule_table[i].lhs]);
-      for (r = &ritem[rule_table[i].rhs]; *r > 0; r++)
+      for (r = &ritem[rule_table[i].rhs]; *r >= 0; r++)
 	fprintf (out, " %s", tags[*r]);
       fputc ('\n', out);
     }
   fprintf (out, "\n\n");
 }
-#endif
 
 
 
@@ -490,24 +502,27 @@ static void
 reduce_print (void)
 {
   if (yacc_flag && nuseless_productions)
-    fprintf (stderr, _("%d rules never reduced\n"), 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, _("%d useless nonterminal%s"),
-	       nuseless_nonterminals,
-	       (nuseless_nonterminals == 1 ? "" : "s"));
-    }
+    fprintf (stderr, ngettext ("%d useless nonterminal",
+			       "%d useless nonterminals",
+			       nuseless_nonterminals),
+	     nuseless_nonterminals);
+
   if (nuseless_nonterminals > 0 && nuseless_productions > 0)
     fprintf (stderr, _(" and "));
 
   if (nuseless_productions > 0)
-    {
-      fprintf (stderr, _("%d useless rule%s"),
-	       nuseless_productions, (nuseless_productions == 1 ? "" : "s"));
-    }
+    fprintf (stderr, ngettext ("%d useless rule",
+			       "%d useless rules",
+			       nuseless_productions),
+	     nuseless_productions);
   fprintf (stderr, "\n");
   fflush (stderr);
 }
@@ -539,20 +554,17 @@ reduce_grammar (void)
 	   tags[start_symbol]);
 
   reduce_grammar_tables ();
-#if TRACE
-  dump_grammar (stderr);
-#endif
-
-  if (statistics_flag)
-    fprintf (stderr, _("reduced %s defines %d terminal%s, %d nonterminal%s\
-, and %d production%s.\n"),
-	     infile,
-	     ntokens,
-	     (ntokens == 1 ? "" : "s"),
-	     nvars,
-	     (nvars == 1 ? "" : "s"),
-	     nrules,
-	     (nrules == 1 ? "" : "s"));
+  if (nuseless_nonterminals > 0)
+    nonterminals_reduce ();
+
+  if (trace_flag)
+    {
+      dump_grammar (stderr);
+
+      fprintf (stderr, "reduced %s defines %d terminals, %d nonterminals\
+, and %d productions.\n",
+	       infile, ntokens, nvars, nrules);
+    }
 }