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

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This commit is contained in:
Paul Eggert
2002-12-13 08:30:08 +00:00
parent e00b682606
commit 0993971437
1 changed files with 19 additions and 16 deletions
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35
src/nullable.c
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@@ -1,4 +1,5 @@
/* Part of the bison parser generator,
/* Calculate which nonterminals can expand into the null string for Bison.
Copyright (C) 1984, 1989, 2000, 2001, 2002 Free Software Foundation, Inc.
This file is part of Bison, the GNU Compiler Compiler.
@@ -46,7 +47,8 @@ nullable_print (FILE *out)
int i;
fputs ("NULLABLE\n", out);
for (i = ntokens; i < nsyms; i++)
fprintf (out, "\t%s: %s\n", symbols[i]->tag, nullable[i] ? "yes" : "no");
fprintf (out, "\t%s: %s\n", symbols[i]->tag,
nullable[i - ntokens] ? "yes" : "no");
fputs ("\n\n", out);
}
@@ -58,16 +60,16 @@ nullable_compute (void)
symbol_number *s2;
rule_list *p;
symbol_number *squeue = XCALLOC (symbol_number, nvars);
short *rcount = XCALLOC (short, nrules);
symbol_number *squeue = CALLOC (squeue, nvars);
short *rcount = CALLOC (rcount, nrules);
/* RITEM contains all the rules, including useless productions.
Hence we must allocate room for useless nonterminals too. */
rule_list **rsets = XCALLOC (rule_list *, nvars) - ntokens;
rule_list **rsets = CALLOC (rsets, nvars);
/* This is said to be more elements than we actually use.
Supposedly NRITEMS - NRULES is enough. But why take the risk? */
rule_list *relts = XCALLOC (rule_list, nritems + nvars + 1);
rule_list *relts = CALLOC (relts, nritems + nvars + 1);
nullable = XCALLOC (bool, nvars) - ntokens;
CALLOC (nullable, nvars);
s1 = s2 = squeue;
p = relts;
@@ -91,9 +93,9 @@ nullable_compute (void)
for (r = rules_ruleno->rhs; *r >= 0; ++r)
{
rcount[ruleno]++;
p->next = rsets[*r];
p->next = rsets[*r - ntokens];
p->value = rules_ruleno;
rsets[*r] = p;
rsets[*r - ntokens] = p;
p++;
}
}
@@ -102,29 +104,30 @@ nullable_compute (void)
/* This rule has an empty RHS. */
if (item_number_as_rule_number (rules_ruleno->rhs[0]) != ruleno)
abort ();
if (rules_ruleno->useful && !nullable[rules_ruleno->lhs->number])
if (rules_ruleno->useful
&& ! nullable[rules_ruleno->lhs->number - ntokens])
{
nullable[rules_ruleno->lhs->number] = 1;
nullable[rules_ruleno->lhs->number - ntokens] = 1;
*s2++ = rules_ruleno->lhs->number;
}
}
}
while (s1 < s2)
for (p = rsets[*s1++]; p; p = p->next)
for (p = rsets[*s1++ - ntokens]; p; p = p->next)
{
rule *r = p->value;
if (--rcount[r->number] == 0)
if (r->useful && !nullable[r->lhs->number])
if (r->useful && ! nullable[r->lhs->number - ntokens])
{
nullable[r->lhs->number] = 1;
nullable[r->lhs->number - ntokens] = 1;
*s2++ = r->lhs->number;
}
}
XFREE (squeue);
XFREE (rcount);
XFREE (rsets + ntokens);
XFREE (rsets);
XFREE (relts);
if (trace_flag & trace_sets)
@@ -135,5 +138,5 @@ nullable_compute (void)
void
nullable_free (void)
{
XFREE (nullable + ntokens);
XFREE (nullable);
}