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https://github.com/Z3Prover/z3
synced 2026-04-15 08:44:10 +00:00
We should not stop eagerly on local conflicts
This commit is contained in:
CEisenhofer
parent
857e93fdb2
commit
684f93bed4
2 changed files with 62 additions and 49 deletions
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@ -247,29 +247,27 @@ namespace seq {
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return false;
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}
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bool nielsen_node::add_constraint(constraint const &c) {
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void nielsen_node::add_constraint(constraint const &c) {
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auto& m = graph().get_manager();
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if (m.is_and(c.fml)) {
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// We have to add all - even if some of it conflict
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// [otw. we would leave the node partially initialized]
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for (const auto f : *to_app(c.fml)) {
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if (!add_constraint(constraint(f, c.dep, m)))
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return false;
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add_constraint(constraint(f, c.dep, m));
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}
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return true;
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}
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expr* l, *r;
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if (m.is_eq(c.fml, l, r)) {
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if (l == r)
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return true;
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return;
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}
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m_constraints.push_back(c);
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if (m_graph.m_literal_if_false) {
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auto lit = m_graph.m_literal_if_false(c.fml);
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if (lit != sat::null_literal) {
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set_external_conflict(lit, c.dep);
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return false;
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}
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SASSERT(m_graph.m_literal_if_false);
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auto lit = m_graph.m_literal_if_false(c.fml);
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if (lit != sat::null_literal) {
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std::cout << "External literal " << lit << " in node " << m_id << std::endl;
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set_external_conflict(lit, c.dep);
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}
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return true;
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}
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void nielsen_node::apply_subst(euf::sgraph& sg, nielsen_subst const& s) {
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@ -310,7 +308,7 @@ namespace seq {
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if (m_char_ranges.contains(var_id)) {
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auto range = m_char_ranges.find(var_id); // copy exactly
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m_char_ranges.remove(var_id);
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add_char_range(s.m_replacement, range.first, range.second);
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add_char_range(s.m_replacement, range.first, m_graph.dep_mgr().mk_join(range.second, s.m_dep));
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}
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}
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}
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@ -326,7 +324,7 @@ namespace seq {
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return; // matches, no conflict
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}
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set_conflict(backtrack_reason::character_range, dep);
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set_general_conflict(true);
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set_general_conflict();
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return;
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}
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SASSERT(sym_char && sym_char->is_unit());
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@ -337,7 +335,7 @@ namespace seq {
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existing = std::make_pair(inter, graph().dep_mgr().mk_join(existing.second, dep));
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if (inter.is_empty()) {
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set_conflict(backtrack_reason::character_range, existing.second);
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set_general_conflict(true);
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set_general_conflict();
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}
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}
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else
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@ -345,12 +343,14 @@ namespace seq {
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}
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bool nielsen_node::lower_bound(expr* e, rational& lo) const {
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// TODO: Return dependencies
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SASSERT(e);
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return m_graph.m_solver.lower_bound(e, lo);
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}
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bool nielsen_node::upper_bound(expr* e, rational& up) const {
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// TODO: Return dependencies
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SASSERT(e);
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rational v;
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if (m_graph.a.is_numeral(e, v)) {
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@ -490,7 +490,7 @@ namespace seq {
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return t->is_var() || t->is_power();
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});
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if (has_char || !all_eliminable) {
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set_general_conflict(true);
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set_general_conflict();
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set_conflict(backtrack_reason::symbol_clash, dep);
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return true;
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}
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@ -848,7 +848,7 @@ namespace seq {
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++prefix;
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}
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else if (sg.are_unit_distinct(lt, rt)) {
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m_is_general_conflict = true;
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set_general_conflict();
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set_conflict(backtrack_reason::symbol_clash, eq.m_dep);
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return simplify_result::conflict;
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}
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@ -865,7 +865,7 @@ namespace seq {
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if (m.are_equal(lt->get_expr(), rt->get_expr())) {
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++suffix;
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} else if (sg.are_unit_distinct(lt, rt)) {
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m_is_general_conflict = true;
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set_general_conflict();
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set_conflict(backtrack_reason::symbol_clash, eq.m_dep);
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return simplify_result::conflict;
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}
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@ -884,7 +884,8 @@ namespace seq {
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// pass 3: power simplification (mirrors ZIPT's LcpCompression +
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// SimplifyPowerElim + SimplifyPowerSingle)
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for (str_eq& eq : m_str_eq) {
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if (eq.is_trivial() || !eq.m_lhs || !eq.m_rhs)
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SASSERT(eq.m_lhs && eq.m_rhs);
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if (eq.is_trivial())
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continue;
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// 3a: simplify constant-exponent powers (base^0 → ε, base^1 → base)
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@ -1065,7 +1066,7 @@ namespace seq {
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if (!deriv)
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break;
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if (deriv->is_fail()) {
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m_is_general_conflict = true;
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set_general_conflict();
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set_conflict(backtrack_reason::regex, mem.m_dep);
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return simplify_result::conflict;
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}
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@ -1105,7 +1106,7 @@ namespace seq {
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auto next = sg.mk(d);
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if (next->is_fail()) {
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m_is_general_conflict = true;
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set_general_conflict();
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set_conflict(backtrack_reason::regex, mem.m_dep);
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return simplify_result::conflict;
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}
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@ -1119,7 +1120,7 @@ namespace seq {
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// check for regex memberships that are immediately infeasible
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for (str_mem& mem : m_str_mem) {
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if (mem.is_contradiction()) {
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m_is_general_conflict = true;
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set_general_conflict();
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set_conflict(backtrack_reason::regex, mem.m_dep);
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return simplify_result::conflict;
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}
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@ -1137,7 +1138,7 @@ namespace seq {
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continue;
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dep_tracker dep = mem.m_dep;
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if (m_graph.check_regex_widening(*this, mem.m_str, mem.m_regex, dep)) {
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m_is_general_conflict = true;
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set_general_conflict();
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set_conflict(backtrack_reason::regex, dep);
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return simplify_result::conflict;
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}
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@ -1179,7 +1180,7 @@ namespace seq {
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// node as a Parikh-image conflict immediately (avoids a solver call).
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str_mem const* confl_cnstr;
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if (!node.is_currently_conflict() && (confl_cnstr = m_parikh->check_parikh_conflict(node)) != nullptr) {
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node.set_general_conflict(true);
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node.set_general_conflict();
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node.set_conflict(backtrack_reason::parikh_image, confl_cnstr->m_dep);
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}
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}
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@ -1311,7 +1312,8 @@ namespace seq {
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// revisit detection: if already visited this run (e.g., iterative deepening), return cached status.
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// mirrors ZIPT's NielsenNode.GraphExpansion() evalIdx check.
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if (node->eval_idx() == m_run_idx) {
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unsigned eval_idx = node->eval_idx();
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if (eval_idx == m_run_idx) {
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if (node->is_satisfied()) {
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m_sat_node = node;
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m_sat_path = cur_path;
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@ -1323,28 +1325,22 @@ namespace seq {
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}
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node->set_eval_idx(m_run_idx);
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SASSERT(!node->is_general_conflict());
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node->clear_local_conflict(); // clear local conflicts from previous runs
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if (eval_idx > 0)
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// adding the side-conditions from the edge
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// when generating this node might trigger a local conflict
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node->clear_local_conflict(); // clear local conflicts from previous runs
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// we might need to tell the SAT solver about the new integer inequalities
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// that might have been added by an extension step
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assert_node_new_int_constraints(node);
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if (node->is_currently_conflict()) {
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++m_stats.m_num_simplify_conflict;
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return search_result::unsat;
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}
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// simplify constraints (idempotent after first call)
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const simplify_result sr = node->simplify_and_init(cur_path);
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if (sr == simplify_result::conflict) {
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++m_stats.m_num_simplify_conflict;
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node->set_general_conflict(true);
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return search_result::unsat;
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}
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if (node->is_currently_conflict()) {
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if (sr == simplify_result::conflict || node->is_general_conflict()) {
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SASSERT(node->is_general_conflict());
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++m_stats.m_num_simplify_conflict;
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node->set_general_conflict();
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return search_result::unsat;
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}
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@ -1354,7 +1350,8 @@ namespace seq {
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// Note: Parikh filtering is skipped for satisfied nodes (returned above);
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// a fully satisfied node has no remaining memberships to filter.
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apply_parikh_to_node(*node);
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if (node->is_currently_conflict()) {
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if (node->is_general_conflict()) {
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++m_stats.m_num_simplify_conflict;
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return search_result::unsat;
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}
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@ -1368,21 +1365,23 @@ namespace seq {
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generate_node_length_constraints(node);
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assert_node_new_int_constraints(node);
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if (node->is_currently_conflict())
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if (node->is_general_conflict()) {
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++m_stats.m_num_simplify_conflict;
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return search_result::unsat;
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}
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// integer feasibility check: the solver now holds all path constraints
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// incrementally; just query the solver directly
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if (!cur_path.empty() && !check_int_feasibility()) {
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dep_tracker dep = get_subsolver_dependency(node);
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node->set_conflict(backtrack_reason::arithmetic, dep);
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node->set_general_conflict(true);
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node->set_general_conflict();
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++m_stats.m_num_arith_infeasible;
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return search_result::unsat;
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}
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SASSERT(sr != simplify_result::satisfied || node->is_satisfied());
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SASSERT(!node->is_currently_conflict());
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SASSERT(!node->is_general_conflict());
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if (node->is_satisfied()) {
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// Before declaring SAT, check leaf-node regex feasibility:
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@ -1391,7 +1390,7 @@ namespace seq {
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// Mirrors ZIPT NielsenNode.CheckRegex.
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dep_tracker dep;
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if (!check_leaf_regex(*node, dep)) {
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node->set_general_conflict(true);
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node->set_general_conflict();
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node->set_conflict(backtrack_reason::regex, dep);
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return search_result::unsat;
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}
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@ -1400,6 +1399,12 @@ namespace seq {
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return search_result::sat;
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}
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// This is the first time we accept local conflicts
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// Before we only abort on global conflicts [we prefer those]
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// Also we would leave the node in an "instable" state
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if (node->is_currently_conflict())
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return search_result::unsat;
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// depth bound check
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if (depth >= m_depth_bound)
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return search_result::unknown;
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@ -3690,8 +3695,10 @@ namespace seq {
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// We enumerate all nodes rather than having a "todo"-list, as
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// hypothetically the graph could contain cycles in the future
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for (nielsen_node const* n : m_nodes) {
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if (n->reason() == backtrack_reason::children_failed)
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if (n->reason() == backtrack_reason::children_failed) {
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SASSERT(n->m_conflict_external_literal == sat::null_literal);
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continue;
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}
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SASSERT(n->is_currently_conflict());
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if (n->m_conflict_external_literal != sat::null_literal) {
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@ -570,7 +570,8 @@ namespace seq {
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SASSERT(mem.m_regex != nullptr);
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m_str_mem.push_back(mem);
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}
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bool add_constraint(constraint const &ic);
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void add_constraint(constraint const &ic);
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vector<constraint> const& constraints() const { return m_constraints; }
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vector<constraint>& constraints() { return m_constraints; }
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@ -602,13 +603,17 @@ namespace seq {
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// status
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bool is_general_conflict() const { return m_is_general_conflict; }
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void set_general_conflict(bool v) { m_is_general_conflict = v; }
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void set_general_conflict() {
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m_is_general_conflict = true;
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}
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bool is_extended() const { return m_is_extended; }
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void set_extended(bool v) { m_is_extended = v; }
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void set_extended(bool v) {
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m_is_extended = v;
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}
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bool is_currently_conflict() const {
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return m_is_general_conflict ||
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return is_general_conflict() ||
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m_conflict_external_literal != sat::null_literal ||
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(reason() != backtrack_reason::unevaluated && m_is_extended);
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}
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@ -630,11 +635,12 @@ namespace seq {
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}
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void set_conflict(const backtrack_reason r, const dep_tracker confl) {
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if (m_conflict_internal != nullptr)
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if (m_conflict_internal != nullptr && m_conflict_external_literal == sat::null_literal)
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return;
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// We prefer internal conflicts (we need it as a justification for general conflicts)
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m_reason = r;
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m_conflict_internal = confl;
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m_conflict_external_literal = sat::null_literal;
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}
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void set_external_conflict(sat::literal lit, dep_tracker confl) {
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