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z3-z3-4.12.6.src.sat.sat_solver.sat_smt_solver.cpp Maven / Gradle / Ivy
/*++
Copyright (c) 2014 Microsoft Corporation
Module Name:
sat_smt_solver.cpp
Abstract:
incremental solver based on SAT core.
It uses the ast/simplifiers to allow incremental pre-processing that
produce model converters.
Author:
Nikolaj Bjorner (nbjorner) 2022-11-28
Notes:
- add back get_consequences, maybe or just have them handled by inc_sat_solver
- could also port the layered solver used by smtfd and used by get_consequences to simplifiers
--*/
#include "util/gparams.h"
#include "ast/ast_pp.h"
#include "ast/ast_translation.h"
#include "ast/ast_util.h"
#include "solver/solver.h"
#include "model/model_smt2_pp.h"
#include "model/model_evaluator.h"
#include "sat/sat_solver.h"
#include "solver/simplifier_solver.h"
#include "sat/sat_params.hpp"
#include "sat/smt/euf_solver.h"
#include "sat/tactic/goal2sat.h"
#include "sat/tactic/sat2goal.h"
#include "sat/tactic/sat_tactic.h"
#include "sat/sat_simplifier_params.hpp"
// incremental SAT solver.
class sat_smt_solver : public solver {
struct dependency2assumptions {
ast_manager& m;
trail_stack& m_trail;
expr_ref_vector m_refs;
obj_map m_dep2orig; // map original dependency to uninterpreted literal
u_map m_lit2dep; // map from literal assumption to original expression
obj_map m_dep2lit; // map uninterpreted literal to sat literal
sat::literal_vector m_literals;
uint_set m_seen;
dependency2assumptions(ast_manager& m, trail_stack& t):
m(m),
m_trail(t),
m_refs(m)
{}
void reset() {
m_seen.reset();
m_literals.reset();
m_dep2lit.reset();
m_lit2dep.reset();
}
// inserted incrementally
void insert(expr* orig, expr* lit) {
m_trail.push(restore_vector(m_refs));
m_trail.push(insert_obj_map(m_dep2orig, lit));
m_refs.push_back(lit);
m_refs.push_back(orig);
m_dep2orig.insert(lit, orig);
}
// inserted on every check-sat
void insert(expr* dep, sat::literal lit) {
if (m_seen.contains(lit.index()))
return;
m_seen.insert(lit.index());
m_literals.push_back(lit);
m_dep2lit.insert(dep, lit);
m_lit2dep.insert(lit.index(), dep);
}
expr* lit2orig(sat::literal lit) {
expr* e = m_lit2dep[lit.index()];
m_dep2orig.find(e, e);
return e;
}
void copy(ast_translation& tr, dependency2assumptions const& src) {
for (auto const& [k, v] : src.m_dep2orig)
m_dep2orig.insert(tr(k), tr(v));
}
};
mutable sat::solver m_solver;
params_ref m_params;
trail_stack m_trail;
dependency2assumptions m_dep;
goal2sat m_goal2sat;
unsigned m_qhead = 0;
expr_ref_vector m_assumptions, m_core, m_ors, m_fmls, m_internalized_fmls;
atom2bool_var m_map;
mutable model_converter_ref m_cached_mc;
mutable ref m_sat_mc;
std::string m_unknown = "no reason given";
// access formulas after they have been pre-processed and handled by the sat solver.
// this allows to access the internal state of the SAT solver and carry on partial results.
bool m_internalized_converted = false; // have internalized formulas been converted back
bool is_internalized() const { return m_qhead == m_fmls.size(); }
public:
sat_smt_solver(ast_manager& m, params_ref const& p):
solver(m),
m_solver(p, m.limit()),
m_dep(m, m_trail),
m_assumptions(m), m_core(m), m_ors(m), m_fmls(m), m_internalized_fmls(m),
m_map(m) {
updt_params(p);
m_solver.set_incremental(true);
}
solver* translate(ast_manager& dst_m, params_ref const& p) override {
if (m_trail.get_num_scopes() > 0)
throw default_exception("Cannot translate sat solver at non-base level");
ast_translation tr(m, dst_m);
m_solver.pop_to_base_level();
sat_smt_solver* result = alloc(sat_smt_solver, dst_m, p);
auto* ext = get_euf();
if (ext) {
auto& si = result->m_goal2sat.si(dst_m, m_params, result->m_solver, result->m_map, result->m_dep.m_dep2lit, true);
euf::solver::scoped_set_translate st(*ext, dst_m, si);
result->m_solver.copy(m_solver);
}
else {
result->m_solver.copy(m_solver);
}
// TODO: copy preprocess state
for (auto const& [k, v] : m_dep.m_dep2orig) result->m_dep.insert(tr(v), tr(k));
for (expr* f : m_assumptions) result->m_assumptions.push_back(tr(f));
for (auto & kv : m_map) result->m_map.insert(tr(kv.m_key), kv.m_value);
for (expr* f : m_internalized_fmls) result->m_internalized_fmls.push_back(tr(f));
result->m_dep.copy(tr, m_dep);
result->m_internalized_converted = m_internalized_converted;
return result;
}
void set_progress_callback(progress_callback * callback) override {}
void init_check_sat() {
m_solver.pop_to_base_level();
m_core.reset();
m_dep.reset();
m_cached_mc = nullptr;
init_reason_unknown();
m_internalized_converted = false;
}
lbool check_sat_core(unsigned sz, expr * const * _assumptions) override {
init_check_sat();
if (m_solver.inconsistent())
return l_false;
expr_ref_vector assumptions(m);
for (unsigned i = 0; i < sz; ++i)
assumptions.push_back(ensure_literal(_assumptions[i]));
TRACE("sat", tout << assumptions << "\n";);
lbool r = internalize_formulas(assumptions);
if (r != l_true)
return r;
internalize_assumptions(assumptions);
try {
r = m_solver.check(m_dep.m_literals);
}
catch (z3_exception& ex) {
IF_VERBOSE(1, verbose_stream() << "exception: " << ex.msg() << "\n";);
if (m.inc()) {
set_reason_unknown(std::string("(sat.giveup ") + ex.msg() + ')');
return l_undef;
}
r = l_undef;
}
switch (r) {
case l_true:
check_assumptions();
break;
case l_false:
extract_core();
break;
default:
set_reason_unknown(m_solver.get_reason_unknown());
break;
}
return r;
}
void push() override {
try {
expr_ref_vector none(m);
internalize_formulas(none);
}
catch (...) {
push_internal();
throw;
}
push_internal();
}
void push_internal() {
m_solver.user_push();
m_goal2sat.user_push();
m_map.push();
m_trail.push_scope();
m_trail.push(restore_vector(m_assumptions));
m_trail.push(restore_vector(m_fmls));
m_trail.push(value_trail(m_qhead));
}
void pop(unsigned n) override {
n = std::min(n, m_trail.get_num_scopes()); // allow sat_smt_solver to take over for another solver.
m_trail.pop_scope(n);
m_map.pop(n);
m_goal2sat.user_pop(n);
m_solver.user_pop(n);
}
void set_phase(expr* e) override {
bool is_not = m.is_not(e, e);
sat::bool_var b = m_map.to_bool_var(e);
if (b != sat::null_bool_var)
m_solver.set_phase(sat::literal(b, is_not));
}
class sat_phase : public phase, public sat::literal_vector {};
phase* get_phase() override {
sat_phase* p = alloc(sat_phase);
for (unsigned v = m_solver.num_vars(); v-- > 0; )
p->push_back(sat::literal(v, !m_solver.get_phase(v)));
return p;
}
void set_phase(phase* p) override {
for (auto lit : *static_cast(p))
m_solver.set_phase(lit);
}
void move_to_front(expr* e) override {
m.is_not(e, e);
sat::bool_var b = m_map.to_bool_var(e);
if (b != sat::null_bool_var)
m_solver.move_to_front(b);
}
unsigned get_scope_level() const override {
return m_trail.get_num_scopes();
}
bool is_literal(expr* a) const {
m.is_not(a, a);
return is_uninterp_const(a);
}
/*
* Ensure dependencies are literals so that pre-processing can apply to them.
*/
expr* ensure_literal(expr* a) {
if (is_literal(a))
return a;
expr* new_dep = m.mk_fresh_const("dep", m.mk_bool_sort());
expr* fml = m.mk_iff(new_dep, a);
m_fmls.push_back(fml);
m_dep.insert(a, new_dep);
return new_dep;
}
void assert_expr_core2(expr * t, expr * a) override {
m_ors.reset();
m_ors.push_back(t);
if (m.is_and(a)) {
for (expr* arg : *to_app(a)) {
arg = ensure_literal(arg);
m_ors.push_back(mk_not(m, arg));
m_assumptions.push_back(arg);
}
}
else {
a = ensure_literal(a);
m_assumptions.push_back(a);
m_ors.push_back(mk_not(m, a));
}
flatten_or(m_ors);
m_fmls.push_back(mk_or(m_ors));
}
void assert_expr_core(expr * t) override {
m_fmls.push_back(t);
}
ast_manager& get_manager() const override { return m; }
void set_produce_models(bool f) override {}
void collect_param_descrs(param_descrs & r) override {
solver::collect_param_descrs(r);
goal2sat::collect_param_descrs(r);
sat::solver::collect_param_descrs(r);
}
void updt_params(params_ref const & p) override {
m_params.append(p);
sat_params sp(p);
m_params.set_bool("keep_cardinality_constraints", sp.cardinality_solver());
m_params.set_sym("pb.solver", sp.pb_solver());
m_solver.updt_params(m_params);
m_solver.set_incremental(true);
if (sp.smt())
ensure_euf();
}
void collect_statistics(statistics & st) const override {
m_solver.collect_statistics(st);
}
void get_unsat_core(expr_ref_vector & r) override {
r.reset();
r.append(m_core.size(), m_core.data());
}
void get_levels(ptr_vector const& vars, unsigned_vector& depth) override {
unsigned sz = vars.size();
depth.resize(sz);
for (unsigned i = 0; i < sz; ++i) {
auto bv = m_map.to_bool_var(vars[i]);
depth[i] = bv == sat::null_bool_var ? UINT_MAX : m_solver.lvl(bv);
}
}
expr_ref_vector get_trail(unsigned max_level) override {
expr_ref_vector result(m), lit2expr(m);
unsigned sz = m_solver.trail_size();
lit2expr.resize(m_solver.num_vars() * 2);
m_map.mk_inv(lit2expr);
for (unsigned i = 0; i < sz; ++i) {
sat::literal lit = m_solver.trail_literal(i);
if (m_solver.lvl(lit) > max_level)
continue;
expr_ref e(lit2expr.get(lit.index()), m);
if (e)
result.push_back(e);
}
return result;
}
proof * get_proof_core() override {
return nullptr;
}
expr_ref_vector last_cube(bool is_sat) {
expr_ref_vector result(m);
result.push_back(is_sat ? m.mk_true() : m.mk_false());
return result;
}
expr_ref_vector cube(expr_ref_vector& vs, unsigned backtrack_level) override {
lbool r = internalize_formulas(vs);
if (r != l_true) {
IF_VERBOSE(0, verbose_stream() << "internalize produced " << r << "\n");
return expr_ref_vector(m);
}
convert_internalized();
if (m_solver.inconsistent())
return last_cube(false);
obj_hashtable _vs;
for (expr* v : vs)
_vs.insert(v);
sat::bool_var_vector vars;
for (auto& kv : m_map)
if (_vs.empty() || _vs.contains(kv.m_key))
vars.push_back(kv.m_value);
sat::literal_vector lits;
lbool result = m_solver.cube(vars, lits, backtrack_level);
expr_ref_vector fmls(m);
expr_ref_vector lit2expr(m);
lit2expr.resize(m_solver.num_vars() * 2);
m_map.mk_inv(lit2expr);
for (sat::literal l : lits) {
expr* e = lit2expr.get(l.index());
SASSERT(e);
fmls.push_back(e);
}
vs.reset();
for (sat::bool_var v : vars) {
expr* x = lit2expr[sat::literal(v, false).index()].get();
if (x)
vs.push_back(x);
}
switch (result) {
case l_true:
return last_cube(true);
case l_false:
return last_cube(false);
default:
break;
}
if (lits.empty())
set_reason_unknown(m_solver.get_reason_unknown());
return fmls;
}
expr* congruence_next(expr* e) override { return e; }
expr* congruence_root(expr* e) override { return e; }
lbool find_mutexes(expr_ref_vector const& vars, vector& mutexes) override {
sat::literal_vector ls;
u_map lit2var;
for (expr * e : vars) {
expr* atom = e;;
bool neg = m.is_not(e, atom);
sat::bool_var v = m_map.to_bool_var(atom);
if (v != sat::null_bool_var) {
sat::literal lit(v, neg);
ls.push_back(lit);
lit2var.insert(lit.index(), e);
}
}
vector ls_mutexes;
m_solver.find_mutexes(ls, ls_mutexes);
for (sat::literal_vector const& ls_mutex : ls_mutexes) {
expr_ref_vector mutex(m);
for (sat::literal l : ls_mutex)
mutex.push_back(lit2var.find(l.index()));
mutexes.push_back(mutex);
}
return l_true;
}
void init_reason_unknown() {
m_unknown = "no reason given";
}
std::string reason_unknown() const override {
return m_unknown;
}
void set_reason_unknown(char const* msg) override {
m_unknown = msg;
}
void set_reason_unknown(std::string &&msg) {
m_unknown = std::move(msg);
}
void get_labels(svector & r) override {
}
unsigned get_num_assertions() const override {
const_cast(this)->convert_internalized();
if (is_internalized() && m_internalized_converted)
return m_internalized_fmls.size();
else
return m_fmls.size();
}
expr * get_assertion(unsigned idx) const override {
if (is_internalized() && m_internalized_converted)
return m_internalized_fmls[idx];
return m_fmls.get(idx);
}
unsigned get_num_assumptions() const override {
return m_assumptions.size();
}
expr * get_assumption(unsigned idx) const override {
return m_assumptions[idx];
}
model_converter_ref get_model_converter() const override {
const_cast(this)->convert_internalized();
if (m_cached_mc)
return m_cached_mc;
if (is_internalized() && m_internalized_converted) {
if (m_sat_mc) m_sat_mc->flush_smc(m_solver, m_map);
m_cached_mc = concat(solver::get_model_converter().get(), m_sat_mc.get());
TRACE("sat", m_cached_mc->display(tout););
return m_cached_mc;
}
else {
return solver::get_model_converter();
}
}
void convert_internalized() {
m_solver.pop_to_base_level();
expr_ref_vector none(m);
internalize_formulas(none);
if (!is_internalized() || m_internalized_converted)
return;
sat2goal s2g;
m_cached_mc = nullptr;
goal g(m, false, true, false);
s2g(m_solver, m_map, m_params, g, m_sat_mc);
m_internalized_fmls.reset();
g.get_formulas(m_internalized_fmls);
TRACE("sat", m_solver.display(tout); tout << m_internalized_fmls << "\n";);
m_internalized_converted = true;
}
euf::solver* get_euf() {
return dynamic_cast(m_solver.get_extension());
}
void init_goal2sat() {
m_goal2sat.init(m, m_params, m_solver, m_map, m_dep.m_dep2lit, true);
}
euf::solver* ensure_euf() {
init_goal2sat();
return m_goal2sat.ensure_euf();
}
void register_on_clause(void* ctx, user_propagator::on_clause_eh_t& on_clause) override {
ensure_euf()->register_on_clause(ctx, on_clause);
}
void user_propagate_init(
void* ctx,
user_propagator::push_eh_t& push_eh,
user_propagator::pop_eh_t& pop_eh,
user_propagator::fresh_eh_t& fresh_eh) override {
ensure_euf()->user_propagate_init(ctx, push_eh, pop_eh, fresh_eh);
}
void user_propagate_register_fixed(user_propagator::fixed_eh_t& fixed_eh) override {
ensure_euf()->user_propagate_register_fixed(fixed_eh);
}
void user_propagate_register_final(user_propagator::final_eh_t& final_eh) override {
ensure_euf()->user_propagate_register_final(final_eh);
}
void user_propagate_register_eq(user_propagator::eq_eh_t& eq_eh) override {
ensure_euf()->user_propagate_register_eq(eq_eh);
}
void user_propagate_register_diseq(user_propagator::eq_eh_t& diseq_eh) override {
ensure_euf()->user_propagate_register_diseq(diseq_eh);
}
void user_propagate_register_expr(expr* e) override {
ensure_euf()->user_propagate_register_expr(e);
}
void user_propagate_register_created(user_propagator::created_eh_t& r) override {
ensure_euf()->user_propagate_register_created(r);
}
void user_propagate_register_decide(user_propagator::decide_eh_t& r) override {
ensure_euf()->user_propagate_register_decide(r);
}
private:
void add_assumption(expr* a) {
init_goal2sat();
m_dep.insert(a, m_goal2sat.internalize(a));
}
void internalize_assumptions(expr_ref_vector const& asms) {
for (expr* a : asms)
add_assumption(a);
for (expr* a : m_assumptions)
add_assumption(a);
}
lbool internalize_formulas(expr_ref_vector& assumptions) {
if (is_internalized() && assumptions.empty())
return l_true;
TRACE("sat", tout << "qhead " << m_qhead << "\n");
m_internalized_converted = false;
m_solver.pop_to_base_level();
init_goal2sat();
m_goal2sat(m_fmls.size() - m_qhead, m_fmls.data() + m_qhead);
if (!m_sat_mc)
m_sat_mc = alloc(sat2goal::mc, m);
m_sat_mc->flush_smc(m_solver, m_map);
m_qhead = m_fmls.size();
return m.inc() ? l_true : l_undef;
}
void extract_core() {
m_core.reset();
if (m_dep.m_literals.empty())
return;
for (sat::literal c : m_solver.get_core())
m_core.push_back(m_dep.lit2orig(c));
TRACE("sat",
tout << "core: " << m_solver.get_core() << "\n";
tout << "core: " << m_core << "\n";
m_solver.display(tout));
}
void check_assumptions() {
sat::model const& ll_m = m_solver.get_model();
for (auto const& [k, lit] : m_dep.m_dep2lit) {
if (sat::value_at(lit, ll_m) == l_true)
continue;
IF_VERBOSE(0, verbose_stream() << mk_pp(k, m) << " does not evaluate to true\n";
verbose_stream() << m_dep.m_literals << "\n";
m_solver.display_assignment(verbose_stream());
m_solver.display(verbose_stream()););
throw default_exception("bad state");
}
}
void get_model_core(model_ref & mdl) override {
TRACE("sat", tout << "retrieve model " << (m_solver.model_is_current()?"present":"absent") << "\n";);
mdl = nullptr;
if (!m_solver.model_is_current())
return;
if (m_fmls.size() > m_qhead)
return;
TRACE("sat", m_solver.display_model(tout););
CTRACE("sat", m_sat_mc, m_sat_mc->display(tout););
sat::model ll_m = m_solver.get_model();
mdl = alloc(model, m);
if (m_sat_mc)
(*m_sat_mc)(ll_m);
expr_ref_vector var2expr(m);
m_map.mk_var_inv(var2expr);
for (unsigned v = 0; v < var2expr.size(); ++v) {
expr * n = var2expr.get(v);
if (!n || !is_uninterp_const(n))
continue;
switch (sat::value_at(v, ll_m)) {
case l_true:
mdl->register_decl(to_app(n)->get_decl(), m.mk_true());
break;
case l_false:
mdl->register_decl(to_app(n)->get_decl(), m.mk_false());
break;
default:
break;
}
}
TRACE("sat", m_solver.display(tout););
if (m_sat_mc)
(*m_sat_mc)(mdl);
m_goal2sat.update_model(mdl);
TRACE("sat", model_smt2_pp(tout, m, *mdl, 0););
if (gparams::get_ref().get_bool("model_validate", false)) {
IF_VERBOSE(1, verbose_stream() << "Verifying solution\n";);
model_evaluator eval(*mdl);
eval.set_model_completion(true);
bool all_true = true;
for (expr* f : m_fmls) {
if (has_quantifiers(f))
continue;
expr_ref tmp(m);
eval(f, tmp);
if (m.limit().is_canceled())
return;
CTRACE("sat", !m.is_true(tmp),
tout << "Evaluation failed: " << mk_pp(f, m) << " to " << tmp << "\n";
model_smt2_pp(tout, m, *(mdl.get()), 0););
if (m.is_false(tmp)) {
IF_VERBOSE(0, verbose_stream() << "failed to verify: " << mk_pp(f, m) << "\n");
IF_VERBOSE(0, verbose_stream() << "evaluated to " << tmp << "\n");
all_true = false;
}
}
if (!all_true) {
IF_VERBOSE(0, verbose_stream() << m_params << "\n");
IF_VERBOSE(0, for (auto const& kv : m_map) verbose_stream() << mk_pp(kv.m_key, m) << " |-> " << kv.m_value << "\n");
exit(0);
}
else {
IF_VERBOSE(1, verbose_stream() << "solution verified\n");
}
}
}
};
solver* mk_sat_smt_solver(ast_manager& m, params_ref const& p) {
return mk_simplifier_solver(alloc(sat_smt_solver, m, p), nullptr);
}
