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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
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@ -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) {