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working on BDD reordering

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-10-17 14:20:49 -07:00
parent 4944a86478
commit e0e7836c12
3 changed files with 82 additions and 36 deletions
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85
src/sat/sat_bdd.cpp
View file

@ -238,10 +238,82 @@ namespace sat {
}
void bdd_manager::try_reorder() {
// TBD
init_reorder();
for (unsigned i = 0; i < m_var2level.size(); ++i) {
sift_var(i);
}
}
double bdd_manager::current_cost() {
#if 0
#endif
return m_nodes.size() - m_free_nodes.size();
}
bool bdd_manager::is_bad_cost(double current_cost, double best_cost) const {
return current_cost > 1.1 * best_cost;
}
void bdd_manager::sift_var(unsigned v) {
unsigned lvl = m_var2level[v];
unsigned start = lvl;
double best_cost = current_cost();
bool first = true;
unsigned max_lvl = m_level2nodes.size()-1;
if (lvl*2 < max_lvl) {
goto go_down;
}
go_up:
while (lvl < max_lvl) {
sift_up(lvl);
++lvl;
double cost = current_cost();
if (is_bad_cost(cost, best_cost)) break;
best_cost = std::min(cost, best_cost);
}
if (first) {
first = false;
while (lvl != start) {
sift_up(lvl-1);
--lvl;
}
goto go_down;
}
else {
while (current_cost() != best_cost) {
sift_up(lvl-1);
--lvl;
}
return;
}
go_down:
while (lvl > 0) {
sift_up(lvl-1);
--lvl;
double cost = current_cost();
if (is_bad_cost(cost, best_cost)) break;
best_cost = std::min(cost, best_cost);
}
if (first) {
first = false;
while (lvl != start) {
sift_up(lvl);
++lvl;
}
goto go_up;
}
else {
while (current_cost() != best_cost) {
sift_up(lvl);
++lvl;
}
return;
}
}
void bdd_manager::sift_up(unsigned lvl) {
if (m_level2nodes[lvl].empty()) return;
// exchange level and level + 1.
m_S.reset();
m_T.reset();
@ -326,16 +398,15 @@ namespace sat {
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;
unsigned lvl = n.m_level;
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);
while (m_level2nodes.size() <= lvl) m_level2nodes.push_back(unsigned_vector());
m_level2nodes[lvl].push_back(i);
m_max_parent[n.m_lo] = std::max(m_max_parent[n.m_lo], lvl);
m_max_parent[n.m_hi] = std::max(m_max_parent[n.m_hi], lvl);
}
}

3
src/sat/sat_bdd.h
View file

@ -152,6 +152,9 @@ namespace sat {
void try_reorder();
void init_reorder();
void sift_up(unsigned level);
void sift_var(unsigned v);
double current_cost();
bool is_bad_cost(double new_cost, double best_cost) const;
static const BDD false_bdd = 0;
static const BDD true_bdd = 1;

30
src/sat/sat_lookahead.cpp
View file

@ -1445,35 +1445,7 @@ namespace sat {
m_lookahead_reward += 3.3 * pow(0.5, nonfixed - 2);
break;
case ternary_reward:
if (nonfixed == 2) {
literal l1 = null_literal;
literal l2 = null_literal;
for (literal lit : *n) {
if (!is_fixed(lit)) {
if (l1 == null_literal) {
l1 = lit;
}
else {
SASSERT(l2 != null_literal);
l2 = lit;
break;
}
}
}
if (l1 == null_literal) {
set_conflict();
continue;
}
else if (l2 == null_literal) {
propagated(l1);
}
else {
m_lookahead_reward += (*m_heur)[l1.index()] * (*m_heur)[l2.index()];
}
}
else {
m_lookahead_reward += (double)0.001;
}
UNREACHABLE();
break;
case unit_literal_reward:
break;