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* src/nullable.c (set_nullable): Useless rules must be skipped,

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otherwise, since we range over their symbols, we might look at a
nonterminal which no longer ``exists'', i.e., it is not counted in
`nvars', hence we overflow our arrays.
This commit is contained in:
Akim Demaille
2001-12-15 16:21:44 +00:00
parent 93ede233f5
commit 9c2c67e6fe
2 changed files with 37 additions and 27 deletions
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7
ChangeLog
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@@ -1,3 +1,10 @@
2001-12-15 Akim Demaille <akim@epita.fr>
* src/nullable.c (set_nullable): Useless rules must be skipped,
otherwise, since we range over their symbols, we might look at a
nonterminal which no longer ``exists'', i.e., it is not counted in
`nvars', hence we overflow our arrays.
2001-12-15 Akim Demaille <akim@epita.fr>
The header can also be produced directly, without any obstack!

57
src/nullable.c
View File

@@ -69,35 +69,38 @@ set_nullable (void)
p = relts;
for (ruleno = 1; ruleno < nrules + 1; ++ruleno)
if (ritem[rule_table[ruleno].rhs] > 0)
if (rule_table[ruleno].useful)
{
/* This rule has a non empty RHS. */
short *r;
int any_tokens = 0;
for (r = ritem + rule_table[ruleno].rhs; *r > 0; ++r)
if (ISTOKEN (*r))
any_tokens = 1;
/* This rule has only nonterminals: schedule it for the second
pass. */
if (!any_tokens)
for (r = ritem + rule_table[ruleno].rhs; *r > 0; ++r)
{
rcount[ruleno]++;
p->next = rsets[*r];
p->value = ruleno;
rsets[*r] = p;
p++;
}
}
else
{
/* This rule has an empty RHS. */
assert (ritem[rule_table[ruleno].rhs] == -ruleno);
if (rule_table[ruleno].useful && !nullable[rule_table[ruleno].lhs])
if (ritem[rule_table[ruleno].rhs] > 0)
{
nullable[rule_table[ruleno].lhs] = 1;
*s2++ = rule_table[ruleno].lhs;
/* This rule has a non empty RHS. */
short *r;
int any_tokens = 0;
for (r = ritem + rule_table[ruleno].rhs; *r > 0; ++r)
if (ISTOKEN (*r))
any_tokens = 1;
/* This rule has only nonterminals: schedule it for the second
pass. */
if (!any_tokens)
for (r = ritem + rule_table[ruleno].rhs; *r > 0; ++r)
{
rcount[ruleno]++;
p->next = rsets[*r];
p->value = ruleno;
rsets[*r] = p;
p++;
}
}
else
{
/* This rule has an empty RHS. */
assert (ritem[rule_table[ruleno].rhs] == -ruleno);
if (rule_table[ruleno].useful && !nullable[rule_table[ruleno].lhs])
{
nullable[rule_table[ruleno].lhs] = 1;
*s2++ = rule_table[ruleno].lhs;
}
}
}