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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-10-17 13:25:08 -07:00
parent 42e9a0156b
commit 43f8214453
3 changed files with 88 additions and 28 deletions
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105
src/sat/sat_bdd.cpp
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@ -43,6 +43,8 @@ namespace sat {
m_max_num_bdd_nodes = 1 << 24; // up to 16M nodes
m_mark_level = 0;
alloc_free_nodes(1024 + num_vars);
m_disable_gc = false;
m_is_new_node = false;
// add variables
for (unsigned i = 0; i < num_vars; ++i) {
@ -203,6 +205,7 @@ namespace sat {
}
bdd_manager::BDD bdd_manager::make_node(unsigned level, BDD l, BDD r) {
m_is_new_node = false;
if (l == r) {
return l;
}
@ -214,7 +217,7 @@ namespace sat {
}
e->get_data().m_refcount = 0;
bool do_gc = m_free_nodes.empty();
if (do_gc) {
if (do_gc && !m_disable_gc) {
gc();
e = m_node_table.insert_if_not_there2(n);
e->get_data().m_refcount = 0;
@ -223,15 +226,14 @@ namespace sat {
if (m_nodes.size() > m_max_num_bdd_nodes) {
throw mem_out();
}
e->get_data().m_index = m_nodes.size();
m_nodes.push_back(e->get_data());
alloc_free_nodes(m_nodes.size()/2);
}
else {
e->get_data().m_index = m_free_nodes.back();
m_nodes[e->get_data().m_index] = e->get_data();
m_free_nodes.pop_back();
}
SASSERT(!m_free_nodes.empty());
e->get_data().m_index = m_free_nodes.back();
m_nodes[e->get_data().m_index] = e->get_data();
m_free_nodes.pop_back();
m_is_new_node = true;
return e->get_data().m_index;
}
@ -241,10 +243,45 @@ namespace sat {
void bdd_manager::sift_up(unsigned lvl) {
// exchange level and level + 1.
#if 0
m_relevel.reset(); // nodes to be re-leveled.
m_S.reset();
m_T.reset();
m_disable_gc = true;
for (unsigned n : m_level2nodes[lvl + 1]) {
BDD l = lo(n);
BDD h = hi(n);
if (l == 0 && h == 0) continue;
if ((is_const(l) || level(l) != lvl) &&
(is_const(h) || level(h) != lvl)) {
m_S.push_back(n);
}
else {
m_T.push_back(n);
}
m_node_table.remove(m_nodes[n]);
}
for (unsigned n : m_level2nodes[lvl]) {
bdd_node& node = m_nodes[n];
m_node_table.remove(node);
if (m_max_parent[n] == lvl + 1 && node.m_refcount == 0) {
node.set_internal();
m_free_nodes.push_back(n);
}
else {
node.m_level = lvl + 1;
m_node_table.insert(node);
}
}
for (unsigned n : m_S) {
m_nodes[n].m_level = lvl;
m_node_table.insert(m_nodes[n]);
}
std::swap(m_level2nodes[lvl], m_level2nodes[lvl + 1]);
for (unsigned n : m_T) {
BDD l = lo(n);
BDD h = hi(n);
if (l == 0 && h == 0) continue;
@ -264,28 +301,42 @@ namespace sat {
c = d = h;
}
push(make_node(lvl, a, c));
push(make_node(lvl, b, d));
m_node_table.remove(m_nodes[n]);
m_nodes[n].m_lo = read(2);
m_nodes[n].m_hi = read(1);
m_relevel.push_back(l);
m_relevel.push_back(r);
// TBD: read(2); read(1); should be inserted into m_level2nodes[lvl];
pop(2);
unsigned ac = make_node(lvl, a, c);
if (is_new_node()) {
m_level2nodes[lvl].push_back(ac);
m_max_parent.setx(ac, lvl + 1, 0);
}
unsigned bd = make_node(lvl, b, d);
if (is_new_node()) {
m_level2nodes[lvl].push_back(bd);
m_max_parent.setx(bd, lvl + 1, 0);
}
m_nodes[n].m_lo = ac;
m_nodes[n].m_hi = bd;
m_node_table.insert(m_nodes[n]);
}
unsigned v = m_level2var[lvl];
unsigned w = m_level2var[lvl+1];
std::swap(m_level2var[lvl], m_level2var[lvl+1]);
std::swap(m_var2level[v], m_var2level[w]);
for (unsigned n : m_relevel) {
if (level(n) == lvl) {
// whoever points to n uses it as if it is level lvl + 1.
m_level2nodes[m_node2levelpos[n]];
}
m_disable_gc = false;
}
void bdd_manager::init_reorder() {
m_level2nodes.reset();
unsigned sz = m_nodes.size();
m_max_parent.fill(sz, 0);
for (unsigned i = 0; i < m_level2var.size(); ++i) {
m_level2nodes.push_back(unsigned_vector());
}
for (unsigned i = 0; i < sz; ++i) {
bdd_node const& n = m_nodes[i];
if (n.is_internal()) continue;
SASSERT(i == m_nodes[i].m_index);
m_level2nodes[n.m_level].push_back(i);
m_max_parent[n.m_lo] = std::max(m_max_parent[n.m_lo], n.m_level);
m_max_parent[n.m_hi] = std::max(m_max_parent[n.m_hi], n.m_level);
}
#endif
}
bdd bdd_manager::mk_var(unsigned i) {
@ -498,7 +549,7 @@ namespace sat {
}
for (unsigned i = m_nodes.size(); i-- > 2; ) {
if (!reachable[i]) {
m_nodes[i].m_lo = m_nodes[i].m_hi = 0;
m_nodes[i].set_internal();
m_free_nodes.push_back(i);
}
}
@ -559,7 +610,7 @@ namespace sat {
std::ostream& bdd_manager::display(std::ostream& out) {
for (unsigned i = 0; i < m_nodes.size(); ++i) {
bdd_node const& n = m_nodes[i];
if (n.m_lo == 0 && n.m_hi == 0) continue;
if (n.is_internal()) continue;
out << i << " : " << m_level2var[n.m_level] << " " << n.m_lo << " " << n.m_hi << "\n";
}
return out;