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pwatch

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This commit is contained in:
Jakob Rath 2022-12-01 15:50:03 +01:00
parent 57edd12e36
commit 91c6582bf7
3 changed files with 36 additions and 10 deletions
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38
src/math/polysat/solver.cpp
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@ -76,6 +76,7 @@ namespace polysat {
IF_LOGGING(m_viable.log());
if (is_conflict() && at_base_level()) { LOG_H2("UNSAT"); return l_false; }
else if (is_conflict()) resolve_conflict();
else if (should_add_pwatch()) add_pwatch();
else if (can_propagate()) propagate();
else if (!can_decide()) { LOG_H2("SAT"); SASSERT(verify_sat()); return l_true; }
else if (m_constraints.should_gc()) m_constraints.gc();
@ -335,6 +336,25 @@ namespace polysat {
#endif
}
/** Enqueue constraint c to perform add_pwatch(c) on the next solver iteration */
void solver::enqueue_pwatch(constraint* c) {
SASSERT(c);
if (c->is_pwatched())
return;
m_pwatch_queue.push_back(c);
}
bool solver::should_add_pwatch() const {
return !m_pwatch_queue.empty();
}
void solver::add_pwatch() {
for (constraint* c : m_pwatch_queue) {
add_pwatch(c);
}
m_pwatch_queue.reset();
}
void solver::add_pwatch(constraint* c) {
SASSERT(c);
if (c->is_pwatched())
@ -349,8 +369,10 @@ namespace polysat {
if (vars.size() > 1)
add_pwatch(c, vars[1]);
c->set_pwatched(true);
#if 0
m_pwatch_trail.push_back(c);
m_trail.push_back(trail_instr_t::pwatch_i);
#endif
}
void solver::add_pwatch(constraint* c, pvar v) {
@ -419,12 +441,15 @@ namespace polysat {
m_lemmas.pop_back();
break;
}
#if 0
// NOTE: erase_pwatch should be called when the constraint is deleted from the solver.
case trail_instr_t::pwatch_i: {
constraint* c = m_pwatch_trail.back();
erase_pwatch(c);
m_pwatch_trail.pop_back();
break;
}
#endif
case trail_instr_t::add_var_i: {
// NOTE: currently we cannot delete variables during solving,
// since lemmas may introduce new helper variables if they use operations like bitwise and or pseudo-inverse.
@ -1042,15 +1067,10 @@ namespace polysat {
SASSERT(!clause.empty());
m_constraints.store(&clause, true);
// TODO: we shouldn't add pwatch here immediately, because this may be called during propagate(v); which means the watchlist for v is locked.
// rather, put the clause into a pwatch queue, and add_pwatch in the next solver iteration?
if (!clause.is_redundant()) {
// for (at least) non-redundant clauses, we also need to watch the constraints
// so we can discover when the clause should propagate
// TODO: check if we also need pwatch for redundant clauses
for (sat::literal lit : clause)
add_pwatch(m_constraints.lookup(lit.var()));
}
// Defer add_pwatch until the next solver iteration, because during propagation of a variable v the watchlist for v is locked.
// NOTE: for non-redundant clauses, pwatching its constraints is required for soundness.
for (sat::literal lit : clause)
enqueue_pwatch(lit2cnstr(lit).get());
}
void solver::add_clause(unsigned n, signed_constraint const* cs, bool is_redundant) {