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https://github.com/Z3Prover/z3
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Move some functions; delete old comments
This commit is contained in:
Jakob Rath
parent
e7c9a99d08
commit
b2d926362c
1 changed files with 67 additions and 96 deletions
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@ -795,86 +795,7 @@ namespace polysat {
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}
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}
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jump_level = std::max(jump_level, base_level());
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jump_level = std::max(jump_level, base_level());
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// LOG("current lvl: " << m_level);
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// LOG("base level: " << base_level());
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// LOG("max_level: " << max_level);
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// LOG("jump_level: " << jump_level);
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backjump_and_learn(jump_level, *lemma);
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backjump_and_learn(jump_level, *lemma);
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/*
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m_conflict.reset();
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backjump(jump_level);
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learn_lemma(*lemma);
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*/
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}
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/**
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* Variable activity accounting.
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* As a placeholder we increment activity
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* 1. when a variable assignment is used in a conflict.
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* 2. when a variable propagation is resolved against.
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* The hypothesis that this is useful should be tested against a
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* broader suite of benchmarks and tested with micro-benchmarks.
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* It should be tested in conjunction with restarts.
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*/
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void solver::inc_activity(pvar v) {
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unsigned& act = m_activity[v];
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act += m_activity_inc;
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m_free_pvars.activity_increased_eh(v);
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if (act > (1 << 24))
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rescale_activity();
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}
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void solver::decay_activity() {
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m_activity_inc *= m_variable_decay;
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m_activity_inc /= 100;
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}
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void solver::rescale_activity() {
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for (unsigned& act : m_activity) {
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act >>= 14;
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}
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m_activity_inc >>= 14;
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}
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void solver::report_unsat() {
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backjump(base_level());
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SASSERT(!m_conflict.empty());
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}
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void solver::unsat_core(dependency_vector& deps) {
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deps.reset();
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LOG("conflict" << m_conflict);
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for (auto c : m_conflict) {
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auto d = m_bvars.dep(c.blit());
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if (d != null_dependency)
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deps.push_back(d);
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}
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}
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void solver::learn_lemma(clause& lemma) {
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LOG("Learning: "<< lemma);
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SASSERT(!lemma.empty());
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m_simplify_clause.apply(lemma);
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add_clause(lemma); // propagates undef literals, if possible
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// At this point, all literals in lemma have been value- or bool-propated, if possible.
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// So if the lemma is/was asserting, all its literals are now assigned.
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bool is_asserting = all_of(lemma, [this](sat::literal lit) { return m_bvars.is_assigned(lit); });
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if (!is_asserting) {
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LOG("Lemma is not asserting!");
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m_lemmas.push_back(&lemma);
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m_trail.push_back(trail_instr_t::add_lemma_i);
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// TODO: currently we forget non-asserting lemmas when backjumping over them.
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// We surely don't want to keep them in m_lemmas because then we will start doing case splits
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// even the lemma should instead be waiting for propagations.
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// We could instead watch its pvars and re-insert into m_lemmas when all but one are assigned.
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// The same could even be done in general for all lemmas, instead of distinguishing between
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// asserting and non-asserting lemmas.
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// (Note that the same lemma can be asserting in one branch of the search but non-asserting in another,
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// depending on which pvars are assigned.)
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SASSERT(can_bdecide());
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}
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}
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}
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/**
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/**
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@ -903,14 +824,6 @@ namespace polysat {
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unsigned jump_level = get_level(v) - 1;
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unsigned jump_level = get_level(v) - 1;
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backjump_and_learn(jump_level, *lemma);
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backjump_and_learn(jump_level, *lemma);
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/*
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clause_ref_vector side_lemmas = m_conflict.take_side_lemmas();
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m_conflict.reset();
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backjump(get_level(v) - 1);
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for (auto cl : side_lemmas)
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add_clause(*cl);
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learn_lemma(*lemma);
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*/
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}
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}
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void solver::revert_bool_decision(sat::literal const lit) {
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void solver::revert_bool_decision(sat::literal const lit) {
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@ -928,11 +841,6 @@ namespace polysat {
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unsigned jump_level = m_bvars.level(var) - 1;
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unsigned jump_level = m_bvars.level(var) - 1;
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backjump_and_learn(jump_level, lemma);
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backjump_and_learn(jump_level, lemma);
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/*
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m_conflict.reset();
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backjump(m_bvars.level(var) - 1);
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learn_lemma(lemma);
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*/
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// At this point, the lemma is asserting for ~lit,
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// At this point, the lemma is asserting for ~lit,
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// and has been propagated by learn_lemma/add_clause.
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// and has been propagated by learn_lemma/add_clause.
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SASSERT(all_of(lemma, [this](sat::literal lit1) { return m_bvars.is_assigned(lit1); }));
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SASSERT(all_of(lemma, [this](sat::literal lit1) { return m_bvars.is_assigned(lit1); }));
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@ -956,14 +864,33 @@ namespace polysat {
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learn_lemma(lemma);
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learn_lemma(lemma);
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}
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}
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void solver::learn_lemma(clause& lemma) {
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SASSERT(!lemma.empty());
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m_simplify_clause.apply(lemma);
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add_clause(lemma); // propagates undef literals, if possible
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// At this point, all literals in lemma have been value- or bool-propated, if possible.
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// So if the lemma is/was asserting, all its literals are now assigned.
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bool is_asserting = all_of(lemma, [this](sat::literal lit) { return m_bvars.is_assigned(lit); });
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if (!is_asserting) {
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LOG("Lemma is not asserting!");
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m_lemmas.push_back(&lemma);
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m_trail.push_back(trail_instr_t::add_lemma_i);
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// TODO: currently we forget non-asserting lemmas when backjumping over them.
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// We surely don't want to keep them in m_lemmas because then we will start doing case splits
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// even the lemma should instead be waiting for propagations.
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// We could instead watch its pvars and re-insert into m_lemmas when all but one are assigned.
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// The same could even be done in general for all lemmas, instead of distinguishing between
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// asserting and non-asserting lemmas.
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// (Note that the same lemma can be asserting in one branch of the search but non-asserting in another,
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// depending on which pvars are assigned.)
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SASSERT(can_bdecide());
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}
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}
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bool solver::lemma_invariant(clause const& lemma, assignment_t const& assignment) {
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bool solver::lemma_invariant(clause const& lemma, assignment_t const& assignment) {
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LOG("Lemma: " << lemma);
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LOG("Lemma: " << lemma);
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for (sat::literal lit : lemma) {
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for (sat::literal lit : lemma) {
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LOG(" " << lit_pp(*this, lit));
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LOG(" " << lit_pp(*this, lit));
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// TODO: constraints derived by side lemmas are l_undef at this point!
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// they will be false after backjumping and when the side lemmas are propagated.
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// but at that point, we cannot check is_currently_false anymore, because the assignment was already reset.
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// solution: make a copy of assignment and test invariant after propagating side lemmas (inside learn_lemma?)
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SASSERT(m_bvars.value(lit) == l_false || lit2cnstr(lit).is_currently_false(*this, assignment));
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SASSERT(m_bvars.value(lit) == l_false || lit2cnstr(lit).is_currently_false(*this, assignment));
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}
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}
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return true;
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return true;
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@ -1126,6 +1053,50 @@ namespace polysat {
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return r.is_val();
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return r.is_val();
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}
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}
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/**
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* Variable activity accounting.
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* As a placeholder we increment activity
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* 1. when a variable assignment is used in a conflict.
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* 2. when a variable propagation is resolved against.
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* The hypothesis that this is useful should be tested against a
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* broader suite of benchmarks and tested with micro-benchmarks.
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* It should be tested in conjunction with restarts.
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*/
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void solver::inc_activity(pvar v) {
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unsigned& act = m_activity[v];
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act += m_activity_inc;
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m_free_pvars.activity_increased_eh(v);
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if (act > (1 << 24))
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rescale_activity();
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}
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void solver::decay_activity() {
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m_activity_inc *= m_variable_decay;
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m_activity_inc /= 100;
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}
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void solver::rescale_activity() {
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for (unsigned& act : m_activity) {
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act >>= 14;
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}
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m_activity_inc >>= 14;
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}
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void solver::report_unsat() {
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backjump(base_level());
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SASSERT(!m_conflict.empty());
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}
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void solver::unsat_core(dependency_vector& deps) {
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deps.reset();
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LOG("conflict" << m_conflict);
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for (auto c : m_conflict) {
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auto d = m_bvars.dep(c.blit());
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if (d != null_dependency)
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deps.push_back(d);
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}
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}
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std::ostream& solver::display(std::ostream& out) const {
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std::ostream& solver::display(std::ostream& out) const {
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out << "Search Stack:\n";
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out << "Search Stack:\n";
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for (auto item : m_search) {
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for (auto item : m_search) {
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