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iterative deepening

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2018-10-18 17:14:10 -07:00
parent d22a0d04ed
commit 35eb6eccd1
6 changed files with 101 additions and 53 deletions
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7
src/ast/recfun_decl_plugin.cpp
View file

@ -184,7 +184,8 @@ namespace recfun {
return res;
}
void def::add_case(std::string & name, unsigned n_conditions, expr ** conditions, expr * rhs, bool is_imm) {
void def::add_case(std::string & name, unsigned n_conditions,
expr ** conditions, expr * rhs, bool is_imm) {
case_def c(m, m_fid, this, name, get_domain(), n_conditions, conditions, rhs);
c.set_is_immediate(is_imm);
TRACEFN("add_case " << name << " " << mk_pp(rhs, m)
@ -202,7 +203,7 @@ namespace recfun {
TRACEFN("bug: " << m_name << " has cases already");
UNREACHABLE();
}
SASSERT(n_vars = m_domain.size());
SASSERT(n_vars == m_domain.size());
TRACEFN("compute cases " << mk_pp(rhs0, m));
@ -235,7 +236,7 @@ namespace recfun {
if (m_macro) {
// constant function or trivial control flow, only one (dummy) case
name.append("dummy");
add_case(name, 0, 0, rhs);
add_case(name, 0, nullptr, rhs);
return;
}

34
src/smt/smt_context.cpp
View file

@ -3266,6 +3266,18 @@ namespace smt {
m_assumptions.reset();
}
bool context::should_research(lbool r) {
if (r != l_false || m_unsat_core.empty()) {
return false;
}
for (theory* th : m_theory_set) {
if (th->should_research(m_unsat_core)) {
return true;
}
}
return false;
}
lbool context::mk_unsat_core(lbool r) {
if (r != l_false) return r;
SASSERT(inconsistent());
@ -3353,7 +3365,7 @@ namespace smt {
add_theory_assumptions(theory_assumptions);
if (!theory_assumptions.empty()) {
TRACE("search", tout << "Adding theory assumptions to context" << std::endl;);
return check(theory_assumptions.size(), theory_assumptions.c_ptr(), reset_cancel, true);
return check(0, nullptr, reset_cancel);
}
internalize_assertions();
@ -3407,19 +3419,23 @@ namespace smt {
}
}
lbool context::check(unsigned num_assumptions, expr * const * assumptions, bool reset_cancel, bool already_did_theory_assumptions) {
lbool context::check(unsigned num_assumptions, expr * const * assumptions, bool reset_cancel) {
if (!check_preamble(reset_cancel)) return l_undef;
SASSERT(at_base_level());
setup_context(false);
expr_ref_vector asms(m_manager, num_assumptions, assumptions);
if (!already_did_theory_assumptions) add_theory_assumptions(asms);
add_theory_assumptions(asms);
// introducing proxies: if (!validate_assumptions(asms)) return l_undef;
TRACE("unsat_core_bug", tout << asms << "\n";);
internalize_assertions();
init_assumptions(asms);
TRACE("before_search", display(tout););
lbool r = search();
r = mk_unsat_core(r);
lbool r;
do {
r = search();
r = mk_unsat_core(r);
}
while (should_research(r));
r = check_finalize(r);
return r;
}
@ -3435,8 +3451,12 @@ namespace smt {
internalize_assertions();
init_assumptions(asms);
for (auto const& clause : clauses) init_clause(clause);
lbool r = search();
r = mk_unsat_core(r);
lbool r;
do {
r = search();
r = mk_unsat_core(r);
}
while (should_research(r));
r = check_finalize(r);
return r;
}

4
src/smt/smt_context.h
View file

@ -1137,6 +1137,8 @@ namespace smt {
void add_theory_assumptions(expr_ref_vector & theory_assumptions);
lbool mk_unsat_core(lbool result);
bool should_research(lbool result);
void validate_unsat_core();
@ -1524,7 +1526,7 @@ namespace smt {
void pop(unsigned num_scopes);
lbool check(unsigned num_assumptions = 0, expr * const * assumptions = nullptr, bool reset_cancel = true, bool already_did_theory_assumptions = false);
lbool check(unsigned num_assumptions = 0, expr * const * assumptions = nullptr, bool reset_cancel = true);
lbool check(expr_ref_vector const& cube, vector<expr_ref_vector> const& clauses);

9
src/smt/smt_theory.h
View file

@ -194,6 +194,15 @@ namespace smt {
return l_false;
}
/**
\brief This method is called from the smt_context when an unsat core is generated.
The theory may tell the solver to perform iterative deepening by invalidating
this unsat core and increasing some resource constraints.
*/
virtual bool should_research(expr_ref_vector & unsat_core) {
return false;
}
/**
\brief This method is invoked before the search starts.
*/

85
src/smt/theory_recfun.cpp
View file

@ -32,12 +32,10 @@ namespace smt {
m(m),
m_plugin(*reinterpret_cast<recfun_decl_plugin*>(m.get_plugin(get_family_id()))),
m_util(m_plugin.u()),
m_trail(*this),
m_guards(),
m_guards(m),
m_max_depth(0),
m_q_case_expand(),
m_q_body_expand(),
m_q_clauses()
m_q_body_expand()
{
}
@ -89,11 +87,9 @@ namespace smt {
void theory_recfun::reset_queues() {
m_q_case_expand.reset();
m_q_body_expand.reset();
m_q_clauses.reset();
}
void theory_recfun::reset_eh() {
m_trail.reset();
reset_queues();
m_stats.reset();
theory::reset_eh();
@ -116,12 +112,10 @@ namespace smt {
void theory_recfun::push_scope_eh() {
TRACEFN("push_scope");
theory::push_scope_eh();
m_trail.push_scope();
}
void theory_recfun::pop_scope_eh(unsigned num_scopes) {
TRACEFN("pop_scope " << num_scopes);
m_trail.pop_scope(num_scopes);
theory::pop_scope_eh(num_scopes);
reset_queues();
}
@ -131,15 +125,15 @@ namespace smt {
reset_queues();
theory::restart_eh();
}
bool theory_recfun::can_propagate() {
return ! (m_q_case_expand.empty() &&
m_q_body_expand.empty() &&
m_q_clauses.empty());
}
void theory_recfun::propagate() {
for (literal_vector & c : m_q_clauses) {
TRACEFN("add axiom " << pp_lits(ctx(), c));
ctx().mk_th_axiom(get_id(), c);
@ -179,7 +173,7 @@ namespace smt {
c.push_back(~ mk_literal(g));
}
TRACEFN("max-depth limit: add clause " << pp_lits(ctx(), c));
SASSERT(std::all_of(c.begin(), c.end(), [&](literal & l) { return ctx().get_assignment(l) == l_false; })); // conflict
SASSERT(std::all_of(c.begin(), c.end(), [&](literal & l) { return ctx().get_assignment(l) == l_false; })); // conflict
m_q_clauses.push_back(std::move(c));
}
@ -190,26 +184,23 @@ namespace smt {
*/
void theory_recfun::assign_eh(bool_var v, bool is_true) {
expr* e = ctx().bool_var2expr(v);
if (!is_true || !is_app(e)) return;
app* a = to_app(e);
if (u().is_case_pred(a)) {
TRACEFN("assign_case_pred_true "<< mk_pp(e,m));
if (is_true && u().is_case_pred(e)) {
app* a = to_app(e);
TRACEFN("assign_case_pred_true " << mk_pp(e, m));
// add to set of local assumptions, for depth-limit purpose
SASSERT(!m_guards.contains(e));
m_guards.insert(e);
m.inc_ref(e);
insert_ref_map<theory_recfun,guard_set,ast_manager,expr*> trail_elt(m, m_guards, e);
m_trail.push(trail_elt);
SASSERT(!m_guards.contains(a));
m_guards.push_back(a);
ctx().push_trail(push_back_vector<context, app_ref_vector>(m_guards));
if (m_guards.size() > get_max_depth()) {
// too many body-expansions: depth-limit conflict
max_depth_conflict();
}
else {
if (m_guards.size() <= get_max_depth()) {
// body-expand
body_expansion b_e(u(), a);
push_body_expand(std::move(b_e));
}
else {
// too many body-expansions: depth-limit conflict
max_depth_conflict();
}
}
}
@ -238,7 +229,19 @@ namespace smt {
}
literal theory_recfun::mk_eq_lit(expr* l, expr* r) {
literal lit = mk_eq(l, r, false);
literal lit;
if (m.is_true(r) || m.is_false(r)) {
std::swap(l, r);
}
if (m.is_true(l)) {
lit = mk_literal(r);
}
else if (m.is_false(l)) {
lit = ~mk_literal(r);
}
else {
lit = mk_eq(l, r, false);
}
ctx().mark_as_relevant(lit);
return lit;
}
@ -326,6 +329,21 @@ namespace smt {
}
final_check_status theory_recfun::final_check_eh() {
if (m_guards.size() > get_max_depth()) {
#if 1
return FC_GIVEUP;
#else
for (unsigned i = get_max_depth(); i < m_guards.size(); ++i) {
app* a = m_guards.get(i);
body_expansion b_e(u(), a);
push_body_expand(std::move(b_e));
}
unsigned new_depth = m_guards.size() + 1;
IF_VERBOSE(2, verbose_stream() << "(smt.recfun :new-depth " << new_depth << ")\n");
set_max_depth(new_depth);
return FC_CONTINUE;
#endif
}
return FC_DONE;
}
@ -335,13 +353,16 @@ namespace smt {
assumptions.push_back(dlimit);
}
// if `dlimit` occurs in unsat core, return "unknown"
lbool theory_recfun::validate_unsat_core(expr_ref_vector & unsat_core) {
// if `dlimit` occurs in unsat core, return 'true'
bool theory_recfun::should_research(expr_ref_vector & unsat_core) {
for (auto & e : unsat_core) {
if (u().is_depth_limit(e))
return l_undef;
if (u().is_depth_limit(e)) {
unsigned new_depth = (3 * (1 + get_max_depth())) / 2;
set_max_depth(new_depth);
return true;
}
}
return l_false;
return false;
}
void theory_recfun::display(std::ostream & out) const {

15
src/smt/theory_recfun.h
View file

@ -72,8 +72,7 @@ namespace smt {
body_expansion(recfun_util& u, app * n) : m_cdef(0), m_args() {
SASSERT(u.is_case_pred(n));
m_cdef = &u.get_case_def(n->get_name());
for (expr * arg : *n)
m_args.push_back(arg);
m_args.append(n->get_num_args(), n->get_args());
}
body_expansion(recfun_case_def const & d, ptr_vector<expr> & args) : m_cdef(&d), m_args(args) {}
body_expansion(body_expansion const & from): m_cdef(from.m_cdef), m_args(from.m_args) {}
@ -88,16 +87,11 @@ namespace smt {
friend std::ostream& operator<<(std::ostream&, pp_body_expansion const &);
typedef trail_stack<theory_recfun> th_trail_stack;
typedef obj_hashtable<expr> guard_set;
ast_manager& m;
recfun_decl_plugin& m_plugin;
recfun_util& m_util;
stats m_stats;
th_trail_stack m_trail;
guard_set m_guards; // true case-preds
app_ref_vector m_guards; // true case-preds
unsigned m_max_depth; // for fairness and termination
vector<case_expansion> m_q_case_expand;
@ -117,8 +111,8 @@ namespace smt {
void assert_macro_axiom(case_expansion & e);
void assert_case_axioms(case_expansion & e);
void assert_body_axiom(body_expansion & e);
void max_depth_conflict(void);
literal mk_literal(expr* e);
void max_depth_conflict();
literal mk_eq_lit(expr* l, expr* r);
bool is_standard_order(recfun::vars const& vars) const { return vars.size() == 0 || vars[vars.size()-1]->get_idx() == 0; }
protected:
@ -137,7 +131,7 @@ namespace smt {
void restart_eh() override;
bool can_propagate() override;
void propagate() override;
lbool validate_unsat_core(expr_ref_vector &) override;
bool should_research(expr_ref_vector &) override;
void new_eq_eh(theory_var v1, theory_var v2) override {}
void new_diseq_eh(theory_var v1, theory_var v2) override {}
@ -152,6 +146,7 @@ namespace smt {
virtual void collect_statistics(::statistics & st) const override;
unsigned get_max_depth() const { return m_max_depth; }
void set_max_depth(unsigned n) { SASSERT(n>0); m_max_depth = n; }
void inc_max_depth() { ++m_max_depth; }
};
}