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fix gc bug

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This commit is contained in:
Nikolaj Bjorner 2019-12-23 18:29:42 -08:00
parent 3df6080a27
commit 34ae55f4f5
2 changed files with 64 additions and 37 deletions
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98
src/math/dd/dd_pdd.cpp
View file

@ -27,7 +27,7 @@ namespace dd {
m_spare_entry = nullptr;
m_max_num_pdd_nodes = 1 << 24; // up to 16M nodes
m_mark_level = 0;
alloc_free_nodes(10*1024 + num_vars);
alloc_free_nodes(1024 + num_vars);
m_disable_gc = false;
m_is_new_node = false;
m_mod2_semantics = false;
@ -36,6 +36,8 @@ namespace dd {
const_info info;
init_value(info, rational::zero()); // becomes pdd_zero
init_value(info, rational::one()); // becomes pdd_one
m_nodes[0].m_refcount = max_rc;
m_nodes[1].m_refcount = max_rc;
for (unsigned i = 2; i <= pdd_no_op + 2; ++i) {
m_nodes.push_back(pdd_node(0,0,0));
m_nodes.back().m_refcount = max_rc;
@ -201,13 +203,13 @@ namespace dd {
unsigned n = read(1); // n = ad + bc
if (!is_val(n) && level(n) == level_p) {
push(apply_rec(ac, hi(n), pdd_add_op));
r = make_node(level_p, lo(n), read(1));
r = make_node(level_p, bd, r);
npop = 6;
push(make_node(level_p, lo(n), read(1)));
r = make_node(level_p, bd, read(1));
npop = 7;
} else {
r = make_node(level_p, n, ac);
r = make_node(level_p, bd, r);
npop = 5;
push(make_node(level_p, n, ac));
r = make_node(level_p, bd, read(1));
npop = 6;
}
}
}
@ -488,12 +490,22 @@ namespace dd {
}
void pdd_manager::init_value(const_info& info, rational const& r) {
pdd_node n(m_values.size());
info.m_value_index = m_values.size();
unsigned vi = 0;
if (m_free_values.empty()) {
vi = m_values.size();
m_values.push_back(r);
}
else {
vi = m_free_values.back();
m_free_values.pop_back();
m_values[vi] = r;
}
m_freeze_value = r;
pdd_node n(vi);
info.m_value_index = vi;
info.m_node_index = insert_node(n);
m_mpq_table.insert(r, info);
m_values.push_back(r);
m_nodes[info.m_node_index].m_refcount = max_rc;
}
pdd_manager::PDD pdd_manager::make_node(unsigned lvl, PDD l, PDD h) {
@ -509,27 +521,32 @@ namespace dd {
node_table::entry* e = m_node_table.insert_if_not_there2(n);
if (e->get_data().m_index != 0) {
unsigned result = e->get_data().m_index;
SASSERT(well_formed(e->get_data()));
return result;
}
e->get_data().m_refcount = 0;
bool do_gc = m_free_nodes.empty();
if (do_gc && !m_disable_gc) {
gc();
SASSERT(n.m_hi == 0 || (!m_free_nodes.contains(n.m_hi) && !m_free_nodes.contains(n.m_lo)));
e = m_node_table.insert_if_not_there2(n);
e->get_data().m_refcount = 0;
e->get_data().m_refcount = 0;
}
if (do_gc && m_free_nodes.size()*3 < m_nodes.size()) {
if (do_gc) {
if (m_nodes.size() > m_max_num_pdd_nodes) {
throw mem_out();
}
alloc_free_nodes(m_nodes.size()/2);
}
SASSERT(e->get_data().m_lo == n.m_lo);
SASSERT(e->get_data().m_hi == n.m_hi);
SASSERT(e->get_data().m_level == n.m_level);
SASSERT(!m_free_nodes.empty());
unsigned result = m_free_nodes.back();
m_free_nodes.pop_back();
e->get_data().m_index = result;
m_nodes[result] = e->get_data();
SASSERT(well_formed(m_nodes[result]));
m_is_new_node = true;
SASSERT(!m_free_nodes.contains(result));
SASSERT(m_nodes[result].m_index == result);
@ -671,12 +688,13 @@ namespace dd {
m_free_nodes.push_back(m_nodes.size());
m_nodes.push_back(pdd_node());
m_nodes.back().m_index = m_nodes.size() - 1;
}
}
m_free_nodes.reverse();
}
void pdd_manager::gc() {
m_free_nodes.reset();
SASSERT(well_formed());
IF_VERBOSE(13, verbose_stream() << "(pdd :gc " << m_nodes.size() << ")\n";);
svector<bool> reachable(m_nodes.size(), false);
for (unsigned i = m_pdd_stack.size(); i-- > 0; ) {
@ -690,24 +708,29 @@ namespace dd {
}
}
while (!m_todo.empty()) {
PDD b = m_todo.back();
PDD p = m_todo.back();
m_todo.pop_back();
SASSERT(reachable[b]);
if (is_val(b)) continue;
if (!reachable[lo(b)]) {
reachable[lo(b)] = true;
m_todo.push_back(lo(b));
SASSERT(reachable[p]);
if (is_val(p)) continue;
if (!reachable[lo(p)]) {
reachable[lo(p)] = true;
m_todo.push_back(lo(p));
}
if (!reachable[hi(b)]) {
reachable[hi(b)] = true;
m_todo.push_back(hi(b));
if (!reachable[hi(p)]) {
reachable[hi(p)] = true;
m_todo.push_back(hi(p));
}
}
for (unsigned i = m_nodes.size(); i-- > 2; ) {
if (!reachable[i]) {
if (is_val(i)) {
if (m_freeze_value == val(i)) continue;
m_free_values.push_back(m_mpq_table.find(val(i)).m_value_index);
m_mpq_table.remove(val(i));
}
m_nodes[i].set_internal();
SASSERT(m_nodes[i].m_refcount == 0);
m_free_nodes.push_back(i);
m_free_nodes.push_back(i);
}
}
// sort free nodes so that adjacent nodes are picked in order of use
@ -805,24 +828,16 @@ namespace dd {
ok &= (lo(n) == 0 && hi(n) == 0 && m_nodes[n].m_refcount == 0);
if (!ok) {
IF_VERBOSE(0,
verbose_stream() << "free node is not internal " << n << " " << lo(n) << " " << hi(n) << " " << m_nodes[n].m_refcount << "\n";
verbose_stream() << "free node is not internal " << n << " "
<< lo(n) << " " << hi(n) << " " << m_nodes[n].m_refcount << "\n";
display(verbose_stream()););
UNREACHABLE();
return false;
}
}
for (pdd_node const& n : m_nodes) {
if (n.is_internal()) continue;
unsigned lvl = n.m_level;
PDD lo = n.m_lo;
PDD hi = n.m_hi;
if (hi == 0) continue; // it is a value
ok &= is_val(lo) || level(lo) < lvl;
ok &= is_val(hi) || level(hi) <= lvl;
ok &= is_val(lo) || !m_nodes[lo].is_internal();
ok &= is_val(hi) || !m_nodes[hi].is_internal();
if (!ok) {
IF_VERBOSE(0, display(verbose_stream() << n.m_index << " lo " << lo << " hi " << hi << "\n"););
if (!well_formed(n)) {
IF_VERBOSE(0, display(verbose_stream() << n.m_index << " lo " << n.m_lo << " hi " << n.m_hi << "\n"););
UNREACHABLE();
return false;
}
@ -830,6 +845,15 @@ namespace dd {
return ok;
}
bool pdd_manager::well_formed(pdd_node const& n) {
PDD lo = n.m_lo;
PDD hi = n.m_hi;
if (n.is_internal() || hi == 0) return true;
bool oklo = is_val(lo) || (level(lo) < n.m_level && !m_nodes[lo].is_internal());
bool okhi = is_val(hi) || (level(hi) <= n.m_level && !m_nodes[hi].is_internal());
return oklo && okhi;
}
std::ostream& pdd_manager::display(std::ostream& out) {
for (unsigned i = 0; i < m_nodes.size(); ++i) {
pdd_node const& n = m_nodes[i];

3
src/math/dd/dd_pdd.h
View file

@ -152,6 +152,8 @@ namespace dd {
unsigned m_max_num_pdd_nodes;
bool m_mod2_semantics;
unsigned_vector m_free_vars;
unsigned_vector m_free_values;
rational m_freeze_value;
PDD make_node(unsigned level, PDD l, PDD r);
PDD insert_node(pdd_node const& n);
@ -201,6 +203,7 @@ namespace dd {
void try_gc();
void reserve_var(unsigned v);
bool well_formed();
bool well_formed(pdd_node const& n);
unsigned_vector m_p, m_q;
rational m_pc, m_qc;