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https://github.com/Z3Prover/z3
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adding bdd package
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
parent
d7b6373601
commit
09fdfcc963
3 changed files with 69 additions and 82 deletions
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@ -24,15 +24,16 @@ namespace sat {
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bdd_manager::bdd_manager(unsigned num_vars, unsigned cache_size) {
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for (BDD a = 0; a < 2; ++a) {
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for (BDD b = 0; b < 2; ++b) {
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for (unsigned op = bdd_and_op; op < bdd_no_op; ++op) {
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for (unsigned op = bdd_and_op; op < bdd_not_op; ++op) {
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unsigned index = a + 2*b + 4*op;
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m_apply_const.reserve(index+1);
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m_apply_const[index] = apply_const(a, b, static_cast<bdd_op>(op));
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}
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}
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}
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// add two dummy nodes for true_bdd and false_bdd
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for (unsigned i = 0; i <= bdd_no_op; ++i) {
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// add dummy nodes for operations, and true, false bdds.
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for (unsigned i = 0; i <= bdd_no_op + 2; ++i) {
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m_nodes.push_back(bdd_node(0,0,0));
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m_nodes.back().m_refcount = max_rc;
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m_nodes.back().m_index = m_nodes.size()-1;
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@ -41,7 +42,7 @@ namespace sat {
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m_spare_entry = nullptr;
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m_max_num_bdd_nodes = 1 << 24; // up to 16M nodes
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m_mark_level = 0;
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alloc_free_nodes(1024);
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alloc_free_nodes(1024 + num_vars);
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// add variables
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for (unsigned i = 0; i < num_vars; ++i) {
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@ -91,6 +92,20 @@ namespace sat {
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}
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}
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bool bdd_manager::check_result(op_entry*& e1, op_entry const* e2, BDD a, BDD b, BDD c) {
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if (e1 != e2) {
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if (e2->m_bdd1 == a && e2->m_bdd2 == b && e2->m_op == c) {
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push_entry(e1);
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return true;
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}
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e1 = const_cast<op_entry*>(e2);
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}
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e1->m_bdd1 = a;
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e1->m_bdd2 = b;
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e1->m_op = c;
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return false;
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}
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bdd_manager::BDD bdd_manager::apply_rec(BDD a, BDD b, bdd_op op) {
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switch (op) {
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case bdd_and_op:
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@ -119,15 +134,8 @@ namespace sat {
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}
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op_entry * e1 = pop_entry(a, b, op);
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op_entry const* e2 = m_op_cache.insert_if_not_there(e1);
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if (e2 != e1) {
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if (e2->m_bdd1 == a && e2->m_bdd2 == b && e2->m_op == op) {
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push_entry(e1);
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return e2->m_result;
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}
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e1 = const_cast<op_entry*>(e2);
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e1->m_bdd1 = a;
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e1->m_bdd2 = b;
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e1->m_op = op;
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if (check_result(e1, e2, a, b, op)) {
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return e2->m_result;
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}
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BDD r;
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if (level(a) == level(b)) {
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@ -221,7 +229,7 @@ namespace sat {
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}
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bdd bdd_manager::mk_var(unsigned i) {
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return bdd(m_var2bdd[2*i+1], this);
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return bdd(m_var2bdd[2*i], this);
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}
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bdd bdd_manager::mk_nvar(unsigned i) {
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@ -247,16 +255,8 @@ namespace sat {
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if (is_false(b)) return true_bdd;
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op_entry* e1 = pop_entry(b, b, bdd_not_op);
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op_entry const* e2 = m_op_cache.insert_if_not_there(e1);
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if (e2 != e1) {
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if (e2->m_bdd1 == b && e2->m_bdd2 == b && e2->m_op == bdd_not_op) {
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push_entry(e1);
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return e2->m_result;
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}
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e1 = const_cast<op_entry*>(e2);
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e1->m_bdd1 = b;
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e1->m_bdd2 = b;
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e1->m_op = bdd_not_op;
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}
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if (check_result(e1, e2, b, b, bdd_not_op))
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return e2->m_result;
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push(mk_not_rec(lo(b)));
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push(mk_not_rec(hi(b)));
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BDD r = make_node(level(b), read(2), read(1));
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@ -264,8 +264,8 @@ namespace sat {
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e1->m_result = r;
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return r;
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}
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bdd bdd_manager::mk_ite(bdd const& c, bdd const& t, bdd const& e) {
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bdd bdd_manager::mk_ite(bdd const& c, bdd const& t, bdd const& e) {
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bool first = true;
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while (true) {
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try {
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@ -290,16 +290,8 @@ namespace sat {
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SASSERT(!is_const(a) && !is_const(b) && !is_const(c));
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op_entry * e1 = pop_entry(a, b, c);
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op_entry const* e2 = m_op_cache.insert_if_not_there(e1);
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if (e2 != e1) {
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if (e2->m_bdd1 == a && e2->m_bdd2 == b && e2->m_op == c) {
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push_entry(e1);
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return e2->m_result;
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}
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e1 = const_cast<op_entry*>(e2);
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e1->m_bdd1 = a;
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e1->m_bdd2 = b;
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e1->m_op = c;
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}
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if (check_result(e1, e2, a, b, c))
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return e2->m_result;
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unsigned la = level(a), lb = level(b), lc = level(c);
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BDD r;
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BDD a1, b1, c1, a2, b2, c2;
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@ -363,16 +355,8 @@ namespace sat {
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bdd_op q_op = op == bdd_and_op ? bdd_and_proj_op : bdd_or_proj_op;
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op_entry * e1 = pop_entry(a, b, q_op);
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op_entry const* e2 = m_op_cache.insert_if_not_there(e1);
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if (e1 != e2) {
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if (e2->m_bdd1 == a && e2->m_bdd2 == b && e2->m_op == q_op) {
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push_entry(e1);
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return e2->m_result;
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}
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e1 = const_cast<op_entry*>(e2);
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e1->m_bdd1 = a;
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e1->m_bdd2 = b;
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e1->m_op = q_op;
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}
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if (check_result(e1, e2, a, b, q_op))
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return e2->m_result;
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push(mk_quant_rec(l, lo(b), op));
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push(mk_quant_rec(l, hi(b), op));
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BDD r = make_node(lvl, read(2), read(1));
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@ -382,11 +366,11 @@ namespace sat {
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}
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}
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double bdd_manager::path_count(bdd const& b) {
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double bdd_manager::count(bdd const& b, unsigned z) {
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init_mark();
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m_path_count.resize(m_nodes.size());
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m_path_count[0] = 0;
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m_path_count[1] = 1;
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m_count.resize(m_nodes.size());
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m_count[0] = z;
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m_count[1] = 1-z;
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set_mark(0);
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set_mark(1);
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m_todo.push_back(b.root);
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@ -402,13 +386,12 @@ namespace sat {
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m_todo.push_back(hi(r));
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}
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else {
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m_path_count[r] = m_path_count[lo(r)] + m_path_count[hi(r)];
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m_count[r] = m_count[lo(r)] + m_count[hi(r)];
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set_mark(r);
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m_todo.pop_back();
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}
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}
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return m_path_count[b.root];
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return m_count[b.root];
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}
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void bdd_manager::alloc_free_nodes(unsigned n) {
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@ -472,6 +455,7 @@ namespace sat {
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++m_mark_level;
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if (m_mark_level == 0) {
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m_mark.fill(0);
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++m_mark_level;
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}
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}
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@ -514,15 +498,15 @@ namespace sat {
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bdd::bdd(int root, bdd_manager* m): root(root), m(m) { m->inc_ref(root); }
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bdd::bdd(bdd & other): root(other.root), m(other.m) { m->inc_ref(root); }
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bdd::~bdd() { m->dec_ref(root); }
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bdd bdd::lo() const { return bdd(m->lo(root), m); }
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bdd bdd::hi() const { return bdd(m->hi(root), m); }
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unsigned bdd::var() const { return m->var(root); }
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bool bdd::is_true() const { return root == bdd_manager::true_bdd; }
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bool bdd::is_false() const { return root == bdd_manager::false_bdd; }
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bdd bdd::operator!() { return m->mk_not(*this); }
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bdd bdd::operator&&(bdd const& other) { return m->mk_and(*this, other); }
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bdd bdd::operator||(bdd const& other) { return m->mk_or(*this, other); }
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std::ostream& bdd::display(std::ostream& out) const { return m->display(out, *this); }
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std::ostream& operator<<(std::ostream& out, bdd const& b) {
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return b.display(out);
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}
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std::ostream& bdd::display(std::ostream& out) const { return m->display(out, *this); }
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std::ostream& operator<<(std::ostream& out, bdd const& b) { return b.display(out); }
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}
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@ -25,13 +25,6 @@ Revision History:
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namespace sat {
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struct bdd_pair {
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int* m_bdd;
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int m_last;
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int m_id;
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bdd_pair* m_next;
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};
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class bdd_manager;
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class bdd {
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@ -42,6 +35,12 @@ namespace sat {
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public:
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bdd(bdd & other);
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~bdd();
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bdd lo() const;
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bdd hi() const;
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unsigned var() const;
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bool is_true() const;
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bool is_false() const;
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bdd operator!();
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bdd operator&&(bdd const& other);
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bdd operator||(bdd const& other);
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@ -123,22 +122,21 @@ namespace sat {
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typedef ptr_hashtable<op_entry, hash_entry, eq_entry> op_table;
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svector<bdd_node> m_nodes;
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op_table m_op_cache;
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node_table m_node_table;
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unsigned_vector m_apply_const;
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svector<BDD> m_bdd_stack;
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op_entry* m_spare_entry;
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svector<BDD> m_var2bdd;
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unsigned_vector m_var2level, m_level2var;
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unsigned_vector m_free_nodes;
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small_object_allocator m_alloc;
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svector<bdd_node> m_nodes;
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op_table m_op_cache;
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node_table m_node_table;
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unsigned_vector m_apply_const;
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svector<BDD> m_bdd_stack;
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op_entry* m_spare_entry;
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svector<BDD> m_var2bdd;
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unsigned_vector m_var2level, m_level2var;
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unsigned_vector m_free_nodes;
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small_object_allocator m_alloc;
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mutable svector<unsigned> m_mark;
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mutable unsigned m_mark_level;
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mutable svector<double> m_path_count;
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mutable svector<double> m_count;
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mutable svector<BDD> m_todo;
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unsigned m_max_num_bdd_nodes;
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unsigned m_max_num_bdd_nodes;
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BDD make_node(unsigned level, BDD l, BDD r);
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@ -157,7 +155,10 @@ namespace sat {
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op_entry* pop_entry(BDD l, BDD r, BDD op);
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void push_entry(op_entry* e);
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bool check_result(op_entry*& e1, op_entry const* e2, BDD a, BDD b, BDD c);
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double count(bdd const& b, unsigned z);
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void gc();
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void alloc_free_nodes(unsigned n);
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void init_mark();
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@ -197,7 +198,8 @@ namespace sat {
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bdd mk_iff(bdd const& a, bdd const& b) { return bdd(apply(a.root, b.root, bdd_iff_op), this); }
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bdd mk_ite(bdd const& c, bdd const& t, bdd const& e);
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double path_count(bdd const& b);
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double dnf_size(bdd const& b) { return count(b, 0); }
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double cnf_size(bdd const& b) { return count(b, 1); }
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std::ostream& display(std::ostream& out, bdd const& b);
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std::ostream& display(std::ostream& out);
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@ -10,12 +10,13 @@ namespace sat {
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bdd c2 = v2 && v0 && v1;
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std::cout << c1 << "\n";
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SASSERT(c1 == c2);
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std::cout << "cnf size: " << m.cnf_size(c1) << "\n";
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c1 = v0 || v1 || v2;
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c2 = v2 || v1 || v0;
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std::cout << c1 << "\n";
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std::cout << c2 << "\n";
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SASSERT(c1 == c2);
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std::cout << "cnf size: " << m.cnf_size(c1) << "\n";
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}
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static void test2() {
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