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Keep most of the Nielsen graph and do a hot-restart when only external literals changed
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CEisenhofer
parent
6321a7c479
commit
0d1ee09e62
3 changed files with 99 additions and 65 deletions
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@ -22,6 +22,8 @@ Author:
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#include "util/statistics.h"
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#include "util/trail.h"
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#include <stack>
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namespace smt {
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theory_nseq::theory_nseq(context& ctx) :
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@ -682,65 +684,90 @@ namespace smt {
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}
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// Fast path: if no new string eq/mem arrived and no scope was popped
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// since the last successful solve, the Nielsen graph and the chosen
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// SAT leaf are identical to what we would rebuild. All of the leaf's
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// arithmetic side-constraints are already assigned true by the outer
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// solver, so the model is valid — skip the rebuild and re-solve.
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if (m_nielsen.sat_node() != nullptr &&
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m_solved_gen == m_constraint_gen &&
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!m_nielsen_literals.empty() &&
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all_of(m_nielsen_literals, [&](auto lit) { return l_true == ctx.get_assignment(lit); })) {
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++m_num_sat_revalidations;
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TRACE(seq, tout << "nseq final_check: revalidated cached SAT path, skipping rebuild\n");
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if (!check_length_coherence()) return FC_CONTINUE;
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if (!check_stoi_coherence()) return FC_CONTINUE;
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if (!has_unhandled_preds()) return FC_DONE;
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return FC_GIVEUP;
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// since the last successful solve, the Nielsen graph can be (at least)
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// partially be reused
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if (m_solved_gen == m_constraint_gen) {
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// SAT leaf are identical to what we would rebuild. All of the leaf's
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// arithmetic side-constraints are already assigned true by the outer
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// solver, so the model is valid — skip the rebuild and re-solve.
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if (m_nielsen.sat_node() != nullptr &&
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!m_nielsen_literals.empty() &&
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all_of(m_nielsen_literals, [&](auto lit) { return l_true == ctx.get_assignment(lit); })) {
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++m_num_sat_revalidations;
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TRACE(seq, tout << "nseq final_check: revalidated cached SAT path, skipping rebuild\n");
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if (!check_length_coherence()) return FC_CONTINUE;
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if (!check_stoi_coherence()) return FC_CONTINUE;
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if (!has_unhandled_preds()) return FC_DONE;
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return FC_GIVEUP;
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}
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// fall through - no reason to rebuild the Nielsen graph
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// everything that is not a general conflict needs to be recomputed
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// but we can keep the general conflicts (which can be a lot!)
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1 == 1;
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0 == 0;
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std::stack<seq::nielsen_node*> to_visit;
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to_visit.push(m_nielsen.root());
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while (!to_visit.empty()) {
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seq::nielsen_node* node = to_visit.top();
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to_visit.pop();
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if (node->is_general_conflict())
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// all its children are general conflicts as well - nothing to do
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continue;
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if (node->is_external_conflict())
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node->clear_local_conflict();
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for (auto& child : node->outgoing()) {
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to_visit.push(child->tgt());
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}
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}
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m_nielsen.clear_sat_node();
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}
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else {
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// let's rebuild the whole Nielsen graph
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populate_nielsen_graph();
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populate_nielsen_graph();
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// assert length constraints derived from string equalities
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if (assert_length_constraints()) {
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TRACE(seq, tout << "nseq final_check: length constraints asserted, FC_CONTINUE\n");
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return FC_CONTINUE;
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}
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SASSERT(m_nielsen.root());
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m_nielsen.assert_node_new_int_constraints(m_nielsen.root());
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++m_num_final_checks;
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m_nielsen.set_max_search_depth(get_fparams().m_nseq_max_depth);
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m_nielsen.set_max_nodes(get_fparams().m_nseq_max_nodes);
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m_nielsen.set_parikh_enabled(get_fparams().m_nseq_parikh);
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m_nielsen.set_signature_split(get_fparams().m_nseq_signature);
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m_nielsen.set_regex_factorization_threshold(get_fparams().m_nseq_regex_factorization_threshold);
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SASSERT(!m_nielsen.root()->is_currently_conflict());
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// Regex membership pre-check: before running DFS, check intersection
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// emptiness for each variable's regex constraints. This handles
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// regex-only problems that the DFS cannot efficiently solve.
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if (!m_nielsen.root()->is_currently_conflict() && get_fparams().m_nseq_regex_precheck) {
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switch (check_regex_memberships_precheck()) {
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case l_true:
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// conflict was asserted inside check_regex_memberships_precheck
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TRACE(seq, tout << "nseq final_check: regex precheck UNSAT\n");
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// assert length constraints derived from string equalities
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if (assert_length_constraints()) {
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TRACE(seq, tout << "nseq final_check: length constraints asserted, FC_CONTINUE\n");
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return FC_CONTINUE;
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case l_false:
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// all regex constraints satisfiable, no word eqs → SAT
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TRACE(seq, tout << "nseq final_check: regex precheck SAT\n");
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m_nielsen.set_sat_node(m_nielsen.root());
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if (!check_length_coherence())
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}
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SASSERT(m_nielsen.root());
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m_nielsen.assert_node_new_int_constraints(m_nielsen.root());
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++m_num_final_checks;
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m_nielsen.set_max_search_depth(get_fparams().m_nseq_max_depth);
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m_nielsen.set_max_nodes(get_fparams().m_nseq_max_nodes);
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m_nielsen.set_parikh_enabled(get_fparams().m_nseq_parikh);
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m_nielsen.set_signature_split(get_fparams().m_nseq_signature);
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m_nielsen.set_regex_factorization_threshold(get_fparams().m_nseq_regex_factorization_threshold);
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SASSERT(!m_nielsen.root()->is_currently_conflict());
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// Regex membership pre-check: before running DFS, check intersection
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// emptiness for each variable's regex constraints. This handles
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// regex-only problems that the DFS cannot efficiently solve.
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if (!m_nielsen.root()->is_currently_conflict() && get_fparams().m_nseq_regex_precheck) {
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switch (check_regex_memberships_precheck()) {
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case l_true:
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// conflict was asserted inside check_regex_memberships_precheck
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TRACE(seq, tout << "nseq final_check: regex precheck UNSAT\n");
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return FC_CONTINUE;
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if (!check_stoi_coherence())
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return FC_CONTINUE;
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TRACE(seq, tout << "pre-check done\n");
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return FC_DONE;
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default:
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break;
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case l_false:
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// all regex constraints satisfiable, no word eqs → SAT
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TRACE(seq, tout << "nseq final_check: regex precheck SAT\n");
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m_nielsen.set_sat_node(m_nielsen.root());
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if (!check_length_coherence())
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return FC_CONTINUE;
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if (!check_stoi_coherence())
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return FC_CONTINUE;
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TRACE(seq, tout << "pre-check done\n");
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return FC_DONE;
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default:
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break;
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}
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}
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}
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@ -757,6 +784,10 @@ namespace smt {
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// std::cout << "Got: " << (result == seq::nielsen_graph::search_result::sat ? "sat" : (result == seq::nielsen_graph::search_result::unsat ? "unsat" : "unknown")) << std::endl;
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#endif
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// Snapshot generation so the fast path can skip a full rebuild
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// on the next call if no new constraints arrive in the meantime.
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m_solved_gen = m_constraint_gen;
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if (result == seq::nielsen_graph::search_result::unsat) {
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IF_VERBOSE(1, verbose_stream() << "nseq final_check: solve UNSAT\n";);
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TRACE(seq, tout << "nseq final_check: solve UNSAT\n");
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@ -773,9 +804,6 @@ namespace smt {
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SASSERT(has_eq_or_mem); // we should have axiomatized them
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bool all_sat = add_nielsen_assumptions();
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// Snapshot generation so the fast path can skip a full rebuild
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// on the next call if no new constraints arrive in the meantime.
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m_solved_gen = m_constraint_gen;
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if (!check_length_coherence())
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return FC_CONTINUE;
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