(nullable_compute): Do not subtract from the returned value of malloc.

[bison.git] / src / derives.c

diff --git a/src/derives.c b/src/derives.c
index a7b86b5b4288448deeb8fabdbe5b9013c5f5133c..da881ecc521e8277974e22adcb88a24c6c39b94b 100644 (file)
--- a/src/derives.c
+++ b/src/derives.c
@@ -1,5 +1,7 @@
 /* Match rules with nonterminals for bison,
-   Copyright 1984, 1989, 2000 Free Software Foundation, Inc.
+
+   Copyright (C) 1984, 1989, 2000, 2001, 2002 Free Software
+   Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
@@ -19,97 +21,101 @@
    Boston, MA 02111-1307, USA.  */
 
 
-/* set_derives finds, for each variable (nonterminal), which rules can
-   derive it.  It sets up the value of derives so that derives[i -
-   ntokens] points to a vector of rule numbers, terminated with -1.
-   */
-
 #include "system.h"
-#include "types.h"
-#include "gram.h"
+
+#include "getargs.h"
+
 #include "derives.h"
+#include "gram.h"
+#include "reader.h"
+#include "symtab.h"
 
-short **derives;
+/* Linked list of rule numbers.  */
+typedef struct rule_list
+{
+  struct rule_list *next;
+  rule *value;
+} rule_list;
 
-#if DEBUG
+rule ***derives = NULL;
 
 static void
 print_derives (void)
 {
   int i;
-  short *sp;
 
-  fputs ("\n\n\n", stdout);
-  printf (_("DERIVES"));
-  fputs ("\n\n", stdout);
+  fputs ("DERIVES\n", stderr);
 
   for (i = ntokens; i < nsyms; i++)
     {
-      printf (_("%s derives"), tags[i]);
-      for (sp = derives[i]; *sp > 0; sp++)
+      rule **rp;
+      fprintf (stderr, "\t%s derives\n", symbols[i]->tag);
+      for (rp = derives[i - ntokens]; *rp; ++rp)
        {
-         printf ("  %d", *sp);
+         fprintf (stderr, "\t\t%3d ", (*rp)->user_number);
+         rule_rhs_print (*rp, stderr);
        }
-      putchar ('\n');
     }
 
-  putchar ('\n');
+  fputs ("\n\n", stderr);
 }
 
-#endif
 
 void
-set_derives (void)
+derives_compute (void)
 {
-  int i;
-  int lhs;
-  shorts *p;
-  short *q;
-  shorts **dset;
-  shorts *delts;
+  symbol_number i;
+  int r;
+  rule **q;
+
+  /* DSET[NTERM - NTOKENS] -- A linked list of the numbers of the rules
+     whose LHS is NTERM.  */
+  rule_list **dset = CALLOC (dset, nvars);
 
-  dset = XCALLOC (shorts *, nvars) - ntokens;
-  delts = XCALLOC (shorts, nrules + 1);
+  /* DELTS[RULE] -- There are NRULES rule number to attach to nterms.
+     Instead of performing NRULES allocations for each, have an array
+     indexed by rule numbers.  */
+  rule_list *delts = CALLOC (delts, nrules);
 
-  p = delts;
-  for (i = nrules; i > 0; i--)
+  for (r = nrules - 1; r >= 0; --r)
     {
-      lhs = rule_table[i].lhs;
-      if (lhs >= 0)
-       {
-         p->next = dset[lhs];
-         p->value = i;
-         dset[lhs] = p;
-         p++;
-       }
+      symbol_number lhs = rules[r].lhs->number;
+      rule_list *p = &delts[r];
+      /* A new LHS is found.  */
+      p->next = dset[lhs - ntokens];
+      p->value = &rules[r];
+      dset[lhs - ntokens] = p;
     }
 
-  derives = XCALLOC (short *, nvars) - ntokens;
-  q = XCALLOC (short, nvars + nrules);
+  /* DSET contains what we need under the form of a linked list.  Make
+     it a single array.  */
+
+  CALLOC (derives, nvars);
+  CALLOC (q, nvars + nrules);
 
   for (i = ntokens; i < nsyms; i++)
     {
-      derives[i] = q;
-      p = dset[i];
+      rule_list *p = dset[i - ntokens];
+      derives[i - ntokens] = q;
       while (p)
        {
          *q++ = p->value;
          p = p->next;
        }
-      *q++ = -1;
+      *q++ = NULL;
     }
 
-#if DEBUG
-  print_derives ();
-#endif
+  if (trace_flag & trace_sets)
+    print_derives ();
 
-  XFREE (dset + ntokens);
-  XFREE (delts);
+  free (dset);
+  free (delts);
 }
 
+
 void
-free_derives (void)
+derives_free (void)
 {
-  XFREE (derives[ntokens]);
-  XFREE (derives + ntokens);
+  XFREE (derives[0]);
+  XFREE (derives);
 }