X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/d854cc9e5a89c4eef71fdbf44a980765e30d6c68..b59b91bb6e46b51bfc7960bacd654ca7b710f3c7:/src/nullable.c?ds=sidebyside

diff --git a/src/nullable.c b/src/nullable.c
index 74164937..8e8809e2 100644
--- a/src/nullable.c
+++ b/src/nullable.c
@@ -28,6 +28,7 @@
 #include "reader.h"
 #include "types.h"
 #include "gram.h"
+#include "reduce.h"
 #include "nullable.h"
 
 char *nullable = NULL;
@@ -64,11 +65,14 @@ set_nullable (void)
   s1 = s2 = squeue;
 
   rcount = XCALLOC (short, nrules + 1);
-  rsets = XCALLOC (shorts *, nvars) - ntokens;
+
+  /* RITEM contains all the rules, including useless productions.
+     Hence we must allocate room for useless nonterminals too.  */
+  rsets = XCALLOC (shorts *, nvars + nuseless_nonterminals) - ntokens;
   /* This is said to be more elements than we actually use.
      Supposedly nitems - nrules is enough.
      But why take the risk?  */
-  relts = XCALLOC (shorts, nitems + nvars + 1);
+  relts = XCALLOC (shorts, nitems + nvars + nuseless_nonterminals + 1);
   p = relts;
 
   for (r = ritem; *r; ++r)
@@ -103,23 +107,16 @@ set_nullable (void)
     }
 
   while (s1 < s2)
-    {
-      p = rsets[*s1++];
-      while (p)
-	{
-	  int ruleno = p->value;
-	  p = p->next;
-	  if (--rcount[ruleno] == 0)
+    for (p = rsets[*s1++]; p; p = p->next)
+      {
+	int ruleno = p->value;
+	if (--rcount[ruleno] == 0)
+	  if (rule_table[ruleno].useful && !nullable[rule_table[ruleno].lhs])
 	    {
-	      int symbol = rule_table[ruleno].lhs;
-	      if (symbol >= 0 && !nullable[symbol])
-		{
-		  nullable[symbol] = 1;
-		  *s2++ = symbol;
-		}
+	      nullable[rule_table[ruleno].lhs] = 1;
+	      *s2++ = rule_table[ruleno].lhs;
 	    }
-	}
-    }
+      }
 
   XFREE (squeue);
   XFREE (rcount);