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sls fixes for ABV. Axiomatization required as saturation can produce conflicts by congruence closure

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2025-01-27 15:16:04 -08:00
parent 2050fc3b35
commit fe1622b592
4 changed files with 110 additions and 40 deletions
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87
src/ast/sls/sls_array_plugin.cpp
View file

@ -24,6 +24,7 @@ namespace sls {
array_plugin::array_plugin(context& ctx):
plugin(ctx),
euf(ctx.euf()),
a(m)
{
m_fid = a.get_family_id();
@ -36,36 +37,67 @@ namespace sls {
m_kv = nullptr;
init_egraph(*m_g);
saturate(*m_g);
#if 0
if (m_g->inconsistent()) {
resolve_conflict();
return false;
}
#endif
return !m_g->inconsistent();
}
void array_plugin::resolve_conflict() {
++m_stats.m_num_conflicts;
auto& g = *m_g;
SASSERT(g.inconsistent());
unsigned n = 0;
sat::literal_vector lits;
ptr_vector<size_t> explain;
g.begin_explain();
g.explain<size_t>(explain, nullptr);
g.end_explain();
verbose_stream() << "conflict\n";
IF_VERBOSE(3, verbose_stream() << "array conflict\n");
bool has_missing_axiom = false;
for (auto p : explain) {
if (is_literal(p)) {
sat::literal l = to_literal(p);
verbose_stream() << l << " " << mk_bounded_pp(ctx.atom(l.var()), m) << " " << ctx.is_unit(l) << "\n";
}
else {
verbose_stream() << mk_bounded_pp(to_expr(p), m) << " == " << mk_bounded_pp(ctx.get_value(to_expr(p)), m) << "\n";
if (is_index(p)) {
has_missing_axiom = true;
unsigned idx = to_index(p);
auto [t, sto, sel] = m_delayed_axioms[idx];
switch (t) {
case store_axiom1:
add_store_axiom1(sto->get_app());
break;
case store_axiom2_down:
case store_axiom2_up:
add_store_axiom2(sto->get_app(), sel->get_app());
break;
case map_axiom:
case const_axiom:
add_eq_axiom(sto, sel);
break;
default:
UNREACHABLE();
break;
}
}
}
if (has_missing_axiom)
return;
sat::literal_vector lits;
for (auto p : explain) {
if (is_enode(p)) {
auto n = to_enode(p);
auto v = ctx.get_value(n->get_expr());
lits.push_back(~ctx.mk_literal(m.mk_eq(n->get_expr(), v)));
if (a.is_store(n->get_expr()))
add_store_axiom1(n->get_app());
}
else if (is_literal(p)) {
sat::literal l = to_literal(p);
lits.push_back(~l);
}
}
IF_VERBOSE(3, verbose_stream() << "add conflict clause\n");
ctx.add_clause(lits);
}
// b ~ a[i -> v]
@ -141,13 +173,12 @@ namespace sls {
if (nmap->get_root() == nsel->get_root())
return;
if (!are_distinct(nsel, nmap)) {
g.merge(nmap, nsel, nullptr);
g.merge(nmap, nsel, to_ptr(map_axiom_index(nmap, nsel)));
g.propagate();
if (!g.inconsistent())
return;
}
expr_ref eq(m.mk_eq(nmap->get_expr(), nsel->get_expr()), m);
ctx.add_theory_axiom(eq);
add_eq_axiom(nmap, nsel);
}
euf::enode* array_plugin::mk_select(euf::egraph& g, euf::enode* b, euf::enode* sel) {
@ -175,10 +206,10 @@ namespace sls {
auto nsel = mk_select(g, n, n);
VERIFY(!g.inconsistent());
if (!are_distinct(nsel, val)) {
g.merge(nsel, val, nullptr);
g.merge(nsel, val, to_ptr(store_axiom1_index(n)));
g.propagate();
if (!g.inconsistent())
return;
return;
}
add_store_axiom1(n->get_app());
}
@ -195,7 +226,7 @@ namespace sls {
return;
auto nsel = mk_select(g, sto->get_arg(0), sel);
if (!are_distinct(nsel, sel)) {
g.merge(nsel, sel, nullptr);
g.merge(nsel, sel, to_ptr(store_axiom2_down_index(sto, sel)));
g.propagate();
if (!g.inconsistent())
return;
@ -215,7 +246,7 @@ namespace sls {
return;
auto nsel = mk_select(g, sto, sel);
if (!are_distinct(nsel, sel)) {
g.merge(nsel, sel, nullptr);
g.merge(nsel, sel, to_ptr(store_axiom2_up_index(sto, sel)));
g.propagate();
if (!g.inconsistent())
return;
@ -234,13 +265,13 @@ namespace sls {
auto val = cn->get_arg(0);
auto nsel = mk_select(g, cn, sel);
if (!are_distinct(nsel, sel)) {
g.merge(nsel, sel, nullptr);
g.merge(nsel, sel, to_ptr(const_axiom_index(val, nsel)));
g.propagate();
if (!g.inconsistent())
return;
}
expr_ref eq(m.mk_eq(val->get_expr(), nsel->get_expr()), m);
ctx.add_theory_axiom(eq);
++m_stats.m_num_axioms;
add_eq_axiom(val, nsel);
}
bool array_plugin::are_distinct(euf::enode* a, euf::enode* b) {
@ -270,6 +301,7 @@ namespace sls {
expr_ref sel(a.mk_select(args), m);
expr_ref eq(m.mk_eq(sel, to_app(sto)->get_arg(sto->get_num_args() - 1)), m);
IF_VERBOSE(3, verbose_stream() << "add store axiom 1 " << mk_bounded_pp(sto, m) << "\n");
++m_stats.m_num_axioms;
ctx.add_theory_axiom(eq);
}
@ -291,6 +323,7 @@ namespace sls {
for (unsigned i = 1; i < sel->get_num_args() - 1; ++i)
ors.push_back(m.mk_eq(sel->get_arg(i), sto->get_arg(i)));
IF_VERBOSE(3, verbose_stream() << "add store axiom 2 " << mk_bounded_pp(sto, m) << " " << mk_bounded_pp(sel, m) << "\n");
++m_stats.m_num_axioms;
ctx.add_theory_axiom(m.mk_or(ors));
}
@ -307,11 +340,13 @@ namespace sls {
n1 = n1 ? n1 : g.mk(t, 0, args.size(), args.data());
if (a.is_array(t))
continue;
if (m.is_bool(t))
continue;
auto v = ctx.get_value(t);
IF_VERBOSE(3, verbose_stream() << "init " << mk_bounded_pp(t, m) << " := " << mk_bounded_pp(v, m) << " " << g.inconsistent() << "\n");
n2 = g.find(v);
n2 = n2 ? n2: g.mk(v, 0, 0, nullptr);
g.merge(n1, n2, to_ptr(t));
g.merge(n1, n2, to_ptr(n1));
}
for (auto lit : ctx.root_literals()) {
if (!ctx.is_true(lit) || lit.sign())
@ -319,9 +354,10 @@ namespace sls {
auto e = ctx.atom(lit.var());
expr* x = nullptr, * y = nullptr;
if (e && m.is_eq(e, x, y))
g.merge(g.find(x), g.find(y), to_ptr(lit));
g.merge(g.find(x), g.find(y), nullptr);
}
g.propagate();
IF_VERBOSE(3, display(verbose_stream()));
@ -388,4 +424,9 @@ namespace sls {
}
return out;
}
void array_plugin::collect_statistics(statistics& st) const {
st.update("sls-array-conflicts", m_stats.m_num_conflicts);
st.update("sls-array-axioms", m_stats.m_num_axioms);
}
}

53
src/ast/sls/sls_array_plugin.h
View file

@ -22,6 +22,8 @@ Author:
namespace sls {
class euf_plugin;
class array_plugin : public plugin {
struct select_args {
euf::enode* sel = nullptr;
@ -29,15 +31,15 @@ namespace sls {
select_args() {}
};
struct select_args_hash {
unsigned operator()(select_args const& a) const {
unsigned operator()(select_args const& a) const {
unsigned h = 0;
for (unsigned i = 1; i < a.sel->num_args(); ++i)
h ^= a.sel->get_arg(i)->get_root()->hash();
h ^= a.sel->get_arg(i)->get_root()->hash();
return h;
};
};
struct select_args_eq {
bool operator()(select_args const& a, select_args const& b) const {
bool operator()(select_args const& a, select_args const& b) const {
SASSERT(a.sel->num_args() == b.sel->num_args());
for (unsigned i = 1; i < a.sel->num_args(); ++i)
if (a.sel->get_arg(i)->get_root() != b.sel->get_arg(i)->get_root())
@ -47,12 +49,37 @@ namespace sls {
};
typedef map<select_args, euf::enode*, select_args_hash, select_args_eq> select2value;
typedef obj_map<euf::enode, select2value> kv;
struct stats {
unsigned m_num_conflicts = 0;
unsigned m_num_axioms = 0;
void reset() { memset(this, 0, sizeof(*this)); }
};
euf_plugin& euf;
array_util a;
scoped_ptr<euf::egraph> m_g;
scoped_ptr<kv> m_kv;
bool m_add_conflicts = true;
bool m_has_arrays = false;
scoped_ptr<kv> m_kv;
bool m_add_conflicts = true;
bool m_has_arrays = false;
stats m_stats;
enum axiom_t { store_axiom1, store_axiom2_down, store_axiom2_up, map_axiom, const_axiom };
struct axiom_instance {
axiom_t t;
euf::enode* sto; euf::enode* sel;
};
svector<axiom_instance> m_delayed_axioms;
unsigned store_axiom1_index(euf::enode* n) { m_delayed_axioms.push_back({ store_axiom1, n, nullptr }); return m_delayed_axioms.size() - 1; }
unsigned store_axiom2_down_index(euf::enode* sto, euf::enode* sel) { m_delayed_axioms.push_back({ store_axiom2_down, sto, sel }); return m_delayed_axioms.size() - 1; }
unsigned store_axiom2_up_index(euf::enode* sto, euf::enode* sel) { m_delayed_axioms.push_back({ store_axiom2_up, sto, sel }); return m_delayed_axioms.size() - 1; }
unsigned map_axiom_index(euf::enode* sto, euf::enode* sel) { m_delayed_axioms.push_back({ map_axiom, sto, sel }); return m_delayed_axioms.size() - 1; }
unsigned const_axiom_index(euf::enode* val, euf::enode* sel) { m_delayed_axioms.push_back({ const_axiom, val, sel }); return m_delayed_axioms.size() - 1; }
void add_eq_axiom(euf::enode* x, euf::enode* y) {
++m_stats.m_num_axioms;
expr_ref eq(m.mk_eq(x->get_expr(), y->get_expr()), m);
ctx.add_theory_axiom(eq);
}
void init_egraph(euf::egraph& g);
void init_kv(euf::egraph& g, kv& kv);
@ -73,10 +100,14 @@ namespace sls {
void resolve_conflict();
size_t* to_ptr(sat::literal l) { return reinterpret_cast<size_t*>((size_t)(l.index() << 4)); };
size_t* to_ptr(expr* t) { return reinterpret_cast<size_t*>((reinterpret_cast<size_t>(t) << 4) + 1); }
bool is_literal(size_t* p) { return (reinterpret_cast<size_t>(p) & 1) == 0; }
size_t* to_ptr(euf::enode* t) { return reinterpret_cast<size_t*>((reinterpret_cast<size_t>(t) << 4) + 1); }
size_t* to_ptr(unsigned n) { return reinterpret_cast<size_t*>((size_t)(n << 4) + 3); }
bool is_literal(size_t* p) { return (reinterpret_cast<size_t>(p) & 3) == 0; }
bool is_index(size_t* p) { return (reinterpret_cast<size_t>(p) & 3) == 3; }
bool is_enode(size_t* p) { return (reinterpret_cast<size_t>(p) & 3) == 1; }
sat::literal to_literal(size_t* p) { return sat::to_literal(static_cast<unsigned>(reinterpret_cast<size_t>(p) >> 4)); };
expr* to_expr(size_t* p) { return reinterpret_cast<expr*>(reinterpret_cast<size_t>(p) >> 4); }
euf::enode* to_enode(size_t* p) { return reinterpret_cast<euf::enode*>(reinterpret_cast<size_t>(p) >> 4); }
unsigned to_index(size_t* p) { return static_cast<unsigned>(reinterpret_cast<size_t>(p) >> 4); }
public:
array_plugin(context& ctx);
@ -95,8 +126,8 @@ namespace sls {
void on_restart() override {}
std::ostream& display(std::ostream& out) const override;
bool set_value(expr* e, expr* v) override { return false; }
void collect_statistics(statistics& st) const override {}
void reset_statistics() override {}
void collect_statistics(statistics& st) const override;
void reset_statistics() override { m_stats.reset(); }
};
}

8
src/ast/sls/sls_context.cpp
View file

@ -315,11 +315,9 @@ namespace sls {
auto p = m_plugins.get(fid, nullptr);
if (p)
return p->get_value(e);
if (m.is_bool(e)) {
sat::bool_var v = m_atom2bool_var.get(e->get_id(), sat::null_bool_var);
if (v != sat::null_bool_var)
return expr_ref(m.mk_bool_val(is_true(v)), m);
}
if (m.is_bool(e))
return expr_ref(m.mk_bool_val(is_true(e)), m);
verbose_stream() << fid << " " << m.get_family_name(fid) << " " << mk_pp(e, m) << "\n";
UNREACHABLE();
return expr_ref(e, m);

2
src/ast/sls/sls_euf_plugin.cpp
View file

@ -90,7 +90,7 @@ namespace sls {
g.explain<size_t>(explain, nullptr);
g.end_explain();
double reward = -1;
TRACE("enf",
TRACE("euf",
for (auto p : explain) {
sat::literal l = to_literal(p);
tout << l << " " << mk_pp(ctx.atom(l.var()), m) << " " << ctx.is_unit(l) << "\n";