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refactor polysat core / solver interface

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2023-12-15 10:40:02 -08:00
parent e2165a78ed
commit cecaf25c6f
6 changed files with 76 additions and 59 deletions
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85
src/sat/smt/polysat/core.cpp
View file

@ -69,19 +69,29 @@ namespace polysat {
void undo() override {
auto& [sc, lit, val] = c.m_constraint_index.back();
auto& vars = sc.vars();
auto idx = c.m_constraint_index.size() - 1;
IF_VERBOSE(10,
verbose_stream() << "undo add watch " << sc << " ";
if (vars.size() > 0) verbose_stream() << "(" << c.m_constraint_index.size() -1 << ": " << c.m_watch[vars[0]] << ") ";
if (vars.size() > 1) verbose_stream() << "(" << c.m_constraint_index.size() -1 << ": " << c.m_watch[vars[1]] << ") ";
if (vars.size() > 0) verbose_stream() << "(" << idx << ": " << c.m_watch[vars[0]] << ") ";
if (vars.size() > 1) verbose_stream() << "(" << idx<< ": " << c.m_watch[vars[1]] << ") ";
verbose_stream() << "\n");
unsigned n = sc.num_watch();
SASSERT(n <= vars.size());
SASSERT(n <= 0 || c.m_watch[vars[0]].back() == c.m_constraint_index.size() - 1);
SASSERT(n <= 1 || c.m_watch[vars[1]].back() == c.m_constraint_index.size() - 1);
if (n > 0)
c.m_watch[vars[0]].pop_back();
auto del_watch = [&](unsigned i) {
auto& w = c.m_watch[vars[i]];
for (unsigned j = w.size(); j-- > 0;) {
if (w[j] == idx) {
std::swap(w[w.size() - 1], w[j]);
w.pop_back();
return;
}
}
UNREACHABLE();
};
if (n > 0)
del_watch(0);
if (n > 1)
c.m_watch[vars[1]].pop_back();
del_watch(1);
c.m_constraint_index.pop_back();
}
};
@ -132,7 +142,7 @@ namespace polysat {
m_var_queue.del_var_eh(v);
}
unsigned core::register_constraint(signed_constraint& sc, dependency d) {
constraint_id core::register_constraint(signed_constraint& sc, dependency d) {
unsigned idx = m_constraint_index.size();
m_constraint_index.push_back({ sc, d, l_undef });
auto& vars = sc.vars();
@ -150,7 +160,7 @@ namespace polysat {
if (j > 1) verbose_stream() << "( " << idx << " : " << m_watch[vars[1]] << ") ";
verbose_stream() << "\n");
s.trail().push(mk_add_watch(*this));
return idx;
return { idx };
}
// case split on unassigned variables until all are assigned values.
@ -202,9 +212,11 @@ namespace polysat {
return sc;
}
void core::propagate_assignment(prop_item& dc) {
auto [idx, sign, dep] = dc;
auto sc = get_constraint(idx, sign);
void core::propagate_assignment(constraint_id idx) {
auto [sc, dep, value] = m_constraint_index[idx.id];
SASSERT(value != l_undef);
if (value == l_false)
sc = ~sc;
if (sc.is_eq(m_var, m_value))
propagate_assignment(m_var, m_value, dep);
else
@ -252,7 +264,9 @@ namespace polysat {
// this can create fresh literals and update m_watch, but
// will not update m_watch[v] (other than copy constructor for m_watch)
// because v has been assigned a value.
sc.propagate(*this, value, dep);
propagate(sc, value, dep);
if (s.inconsistent())
return;
SASSERT(!swapped || vars.size() <= 1 || (!is_assigned(vars[0]) && !is_assigned(vars[1])));
if (swapped)
@ -272,30 +286,17 @@ namespace polysat {
verbose_stream() << "new watch " << v << ": " << m_watch[v] << "\n";
}
void core::propagate_value(prop_item const& dc) {
auto [idx, sign, dep] = dc;
auto sc = get_constraint(idx, sign);
// check if sc evaluates to false
switch (eval(sc)) {
case l_true:
break;
case l_false:
m_unsat_core = explain_eval(sc);
m_unsat_core.push_back(dep);
propagate_unsat_core();
return;
default:
break;
}
void core::propagate_value(constraint_id idx) {
auto [sc, d, value] = m_constraint_index[idx.id];
// propagate current assignment for sc
sc.propagate(*this, to_lbool(!sign), dep);
propagate(sc, value, d);
if (s.inconsistent())
return;
// if sc is v == value, then check the watch list for v to propagate truth assignments
if (sc.is_eq(m_var, m_value)) {
for (auto idx1 : m_watch[m_var]) {
if (idx == idx1)
if (idx.id == idx1)
continue;
auto [sc, d, value] = m_constraint_index[idx1];
switch (eval(sc)) {
@ -312,6 +313,19 @@ namespace polysat {
}
}
void core::propagate(signed_constraint& sc, lbool value, dependency const& d) {
lbool eval_value = eval(sc);
if (eval_value == l_undef)
sc.propagate(*this, value, d);
else if (value == l_undef)
s.propagate(d, eval_value != l_true, explain_eval(sc));
else if (value != eval_value) {
m_unsat_core = explain_eval(sc);
m_unsat_core.push_back(value == l_false ? ~d : d);
propagate_unsat_core();
}
}
void core::get_bitvector_prefixes(pvar v, pvar_vector& out) {
s.get_bitvector_prefixes(v, out);
}
@ -331,7 +345,7 @@ namespace polysat {
s.set_conflict(m_unsat_core);
}
void core::assign_eh(unsigned index, bool sign, dependency const& dep) {
void core::assign_eh(constraint_id index, bool sign, unsigned level) {
struct unassign : public trail {
core& c;
unsigned m_index;
@ -341,9 +355,10 @@ namespace polysat {
c.m_prop_queue.pop_back();
}
};
m_prop_queue.push_back({ index, sign, dep });
m_constraint_index[index].value = to_lbool(!sign);
s.trail().push(unassign(*this, index));
m_prop_queue.push_back(index);
m_constraint_index[index.id].value = to_lbool(!sign);
m_constraint_index[index.id].d.set_level(level);
s.trail().push(unassign(*this, index.id));
}
dependency_vector core::explain_eval(signed_constraint const& sc) {
@ -392,7 +407,7 @@ namespace polysat {
void core::add_axiom(signed_constraint sc) {
auto idx = register_constraint(sc, dependency::axiom());
assign_eh(idx, false, dependency::axiom());
assign_eh(idx, false, 0);
}
void core::add_clause(char const* name, core_vector const& cs, bool is_redundant) {

14
src/sat/smt/polysat/core.h
View file

@ -37,7 +37,6 @@ namespace polysat {
class mk_assign_var;
class mk_add_watch;
typedef svector<std::pair<unsigned, unsigned>> activity;
typedef std::tuple<unsigned, bool, dependency> prop_item;
friend class viable;
friend class constraints;
friend class assignment;
@ -53,7 +52,7 @@ namespace polysat {
constraints m_constraints;
assignment m_assignment;
unsigned m_qhead = 0, m_vqhead = 0;
svector<prop_item> m_prop_queue;
svector<constraint_id> m_prop_queue;
svector<constraint_info> m_constraint_index; // index of constraints
dependency_vector m_unsat_core;
@ -76,17 +75,16 @@ namespace polysat {
void del_var();
bool is_assigned(pvar v) { return !m_justification[v].is_null(); }
void propagate_value(prop_item const& dc);
void propagate_assignment(prop_item& dc);
void propagate_value(constraint_id idx);
void propagate_assignment(constraint_id idx);
void propagate_assignment(pvar v, rational const& value, dependency dep);
void propagate_unsat_core();
void propagate(signed_constraint& sc, lbool value, dependency const& d);
void get_bitvector_prefixes(pvar v, pvar_vector& out);
void get_fixed_bits(pvar v, svector<justified_fixed_bits>& fixed_bits);
bool inconsistent() const;
void add_watch(unsigned idx, unsigned var);
signed_constraint get_constraint(unsigned idx, bool sign);
@ -100,9 +98,9 @@ namespace polysat {
core(solver_interface& s);
sat::check_result check();
unsigned register_constraint(signed_constraint& sc, dependency d);
constraint_id register_constraint(signed_constraint& sc, dependency d);
bool propagate();
void assign_eh(unsigned idx, bool sign, dependency const& d);
void assign_eh(constraint_id idx, bool sign, unsigned level);
pdd value(rational const& v, unsigned sz);
pdd subst(pdd const&);

3
src/sat/smt/polysat/types.h
View file

@ -22,6 +22,7 @@ namespace polysat {
using pdd = dd::pdd;
using pvar = unsigned;
using theory_var = unsigned;
struct constraint_id { unsigned id; };
using pvar_vector = unsigned_vector;
inline const pvar null_var = UINT_MAX;
@ -44,6 +45,8 @@ namespace polysat {
sat::literal literal() const { SASSERT(is_literal()); return *std::get_if<sat::literal>(&m_data); }
std::pair<theory_var, theory_var> eq() const { SASSERT(!is_literal()); return *std::get_if<std::pair<theory_var, theory_var>>(&m_data); }
unsigned level() const { return m_level; }
void set_level(unsigned level) { m_level = level; }
dependency operator~() const { SASSERT(is_literal()); return dependency(~literal(), level()); }
};
inline const dependency null_dependency = dependency(sat::null_literal, UINT_MAX);

2
src/sat/smt/polysat/umul_ovfl_constraint.cpp
View file

@ -97,7 +97,7 @@ namespace polysat {
if (!p.is_val())
return false;
VERIFY(!p.is_zero() && !p.is_one()); // evaluation should catch this case
SASSERT(!p.is_zero() && !p.is_one()); // evaluation should catch this case
rational const& M = p.manager().two_to_N();
auto& C = c.cs();

27
src/sat/smt/polysat_solver.cpp
View file

@ -91,7 +91,7 @@ namespace polysat {
if (!a)
return;
force_push();
m_core.assign_eh(a->m_index, l.sign(), dependency(l, s().lvl(l)));
m_core.assign_eh(a->m_index, l.sign(), s().lvl(l));
}
void solver::set_conflict(dependency_vector const& core) {
@ -115,17 +115,18 @@ namespace polysat {
eqs.push_back(euf::enode_pair(n1, n2));
}
}
DEBUG_CODE({
for (auto lit : core)
VERIFY(s().value(lit) == l_true);
for (auto const& [n1, n2] : eqs)
VERIFY(n1->get_root() == n2->get_root());
});
IF_VERBOSE(10,
for (auto lit : core)
verbose_stream() << " " << lit << ": " << mk_ismt2_pp(literal2expr(lit), m) << "\n";
verbose_stream() << " " << lit << ": " << mk_ismt2_pp(literal2expr(lit), m) << " " << s().value(lit) << "\n";
for (auto const& [n1, n2] : eqs)
verbose_stream() << " " << ctx.bpp(n1) << " == " << ctx.bpp(n2) << "\n";);
DEBUG_CODE({
for (auto lit : core)
SASSERT(s().value(lit) == l_true);
for (auto const& [n1, n2] : eqs)
verbose_stream() << " " << ctx.bpp(n1) << " == " << ctx.bpp(n2) << "\n";);
SASSERT(n1->get_root() == n2->get_root());
});
return { core, eqs };
}
@ -203,8 +204,8 @@ namespace polysat {
m_var_eqs.setx(m_var_eqs_head, {v1, v2}, {v1, v2});
ctx.push(value_trail<unsigned>(m_var_eqs_head));
auto d = dependency(v1, v2, s().scope_lvl());
unsigned index = m_core.register_constraint(sc, d);
m_core.assign_eh(index, false, d);
constraint_id id = m_core.register_constraint(sc, d);
m_core.assign_eh(id, false, s().scope_lvl());
m_var_eqs_head++;
}
@ -218,9 +219,9 @@ namespace polysat {
auto sc = ~m_core.eq(p, q);
sat::literal neq = ~expr2literal(ne.eq());
auto d = dependency(neq, s().lvl(neq));
auto index = m_core.register_constraint(sc, d);
auto id = m_core.register_constraint(sc, d);
TRACE("bv", tout << neq << " := " << s().value(neq) << " @" << s().scope_lvl() << "\n");
m_core.assign_eh(index, false, d);
m_core.assign_eh(id, false, s().lvl(neq));
}
// Core uses the propagate callback to add unit propagations to the trail.

4
src/sat/smt/polysat_solver.h
View file

@ -43,8 +43,8 @@ namespace polysat {
struct atom {
bool_var m_bv;
unsigned m_index;
atom(bool_var b, unsigned index) :m_bv(b), m_index(index) {}
constraint_id m_index;
atom(bool_var b, constraint_id index) :m_bv(b), m_index(index) {}
~atom() { }
};