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iterative deepening per recursive function

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2018-10-18 17:53:11 -07:00
parent 35eb6eccd1
commit c0556b2f64
3 changed files with 52 additions and 45 deletions
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67
src/smt/theory_recfun.cpp
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@ -32,7 +32,7 @@ namespace smt {
m(m),
m_plugin(*reinterpret_cast<recfun_decl_plugin*>(m.get_plugin(get_family_id()))),
m_util(m_plugin.u()),
m_guards(m),
m_guard_preds(m),
m_max_depth(0),
m_q_case_expand(),
m_q_body_expand()
@ -41,10 +41,6 @@ namespace smt {
theory_recfun::~theory_recfun() {
reset_queues();
for (expr* g : m_guards) {
m.dec_ref(g);
}
m_guards.reset();
}
char const * theory_recfun::get_name() const { return "recfun"; }
@ -112,12 +108,21 @@ namespace smt {
void theory_recfun::push_scope_eh() {
TRACEFN("push_scope");
theory::push_scope_eh();
m_guard_preds_lim.push_back(m_guard_preds.size());
}
void theory_recfun::pop_scope_eh(unsigned num_scopes) {
TRACEFN("pop_scope " << num_scopes);
theory::pop_scope_eh(num_scopes);
reset_queues();
// restore guards
unsigned new_lim = m_guard_preds_lim.size()-num_scopes;
for (unsigned i = new_lim; i < m_guard_preds.size(); ++i) {
m_guards[m_guard_preds.get(i)->get_decl()].pop_back();
}
m_guard_preds.resize(m_guard_preds_lim[new_lim]);
m_guard_preds_lim.shrink(new_lim);
}
void theory_recfun::restart_eh() {
@ -159,22 +164,20 @@ namespace smt {
m_q_body_expand.clear();
}
void theory_recfun::max_depth_conflict() {
TRACEFN("max-depth conflict");
void theory_recfun::max_depth_limit(ptr_vector<expr> const& guards) {
TRACEFN("max-depth limit");
literal_vector c;
// make clause `depth_limit => V_{g : guards} ~ g`
{
// first literal must be the depth limit one
app_ref dlimit = m_util.mk_depth_limit_pred(get_max_depth());
c.push_back(~mk_literal(dlimit));
SASSERT(ctx().get_assignment(c.back()) == l_true);
}
for (expr * g : m_guards) {
c.push_back(~ mk_literal(g));
// make clause `depth_limit => V_{g : guards of non-recursive cases} g`
// first literal must be the depth limit one
app_ref dlimit = m_util.mk_depth_limit_pred(get_max_depth());
c.push_back(~mk_literal(dlimit));
SASSERT(ctx().get_assignment(c.back()) == l_false);
for (expr * g : guards) {
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
m_q_clauses.push_back(std::move(c));
}
@ -185,22 +188,11 @@ namespace smt {
void theory_recfun::assign_eh(bool_var v, bool is_true) {
expr* e = ctx().bool_var2expr(v);
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(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()) {
// 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();
}
app* a = to_app(e);
// body-expand
body_expansion b_e(u(), a);
push_body_expand(std::move(b_e));
}
}
@ -297,6 +289,15 @@ namespace smt {
if (c.is_immediate()) {
body_expansion be(c, e.m_args);
assert_body_axiom(be);
// add to set of local assumptions, for depth-limit purpose
func_decl* d = pred_applied->get_decl();
m_guard_preds.push_back(pred_applied);
auto& vec = m_guards.insert_if_not_there2(d, ptr_vector<expr>())->get_data().m_value;
vec.push_back(pred_applied);
if (vec.size() == get_max_depth()) {
max_depth_limit(vec);
}
}
}
}