mirrors/z3
3
0
Fork 0
mirror of https://github.com/Z3Prover/z3 synced 2025-04-29 11:55:51 +00:00
Code Activity

Dedup quot_rem and lshr too

Browse source
This commit is contained in:
Jakob Rath 2022-11-07 15:25:05 +01:00
parent 2953b1c093
commit e7c77a22ab
4 changed files with 71 additions and 40 deletions
Download patch file Download diff file Expand all files Collapse all files

56
src/math/polysat/constraint_manager.cpp
View file

@ -277,19 +277,71 @@ namespace polysat {
return ult(a + shift, b + shift);
}
std::pair<pdd, pdd> constraint_manager::quot_rem(pdd const& a, pdd const& b) {
auto& m = a.manager();
unsigned sz = m.power_of_2();
if (a.is_val() && b.is_val()) {
// TODO: just evaluate?
}
constraint_dedup::quot_rem_args args({a, b});
auto it = m_dedup.quot_rem_expr.find_iterator(args);
if (it != m_dedup.quot_rem_expr.end())
return { m.mk_var(it->m_value.first), m.mk_var(it->m_value.second) };
pdd q = m.mk_var(s.add_var(sz)); // quotient
pdd r = m.mk_var(s.add_var(sz)); // remainder
m_dedup.quot_rem_expr.insert(args, { q.var(), r.var() });
// Axioms for quotient/remainder:
// a = b*q + r
// multiplication does not overflow in b*q
// addition does not overflow in (b*q) + r; for now expressed as: r <= bq+r (TODO: maybe the version with disjunction is easier for the solver; should compare later)
// b ≠ 0 ==> r < b
// b = 0 ==> q = -1
s.add_eq(a, b * q + r);
s.add_umul_noovfl(b, q);
s.add_ule(r, b*q+r);
auto c_eq = eq(b);
s.add_clause(c_eq, ult(r, b), false);
s.add_clause(~c_eq, eq(q + 1), false);
return {q, r};
}
pdd constraint_manager::lshr(pdd const& p, pdd const& q) {
auto& m = p.manager();
unsigned sz = m.power_of_2();
op_constraint_args const args(op_constraint::code::lshr_op, p, q);
auto it = m_dedup.op_constraint_expr.find_iterator(args);
if (it != m_dedup.op_constraint_expr.end())
return m.mk_var(it->m_value);
pdd r = m.mk_var(s.add_var(sz));
m_dedup.op_constraint_expr.insert(args, r.var());
s.assign_eh(lshr(p, q, r), null_dependency);
return r;
}
pdd constraint_manager::bnot(pdd const& p) {
return -p - 1;
}
pdd constraint_manager::band(pdd const& p, pdd const& q) {
op_constraint_args const args(op_constraint::code::and_op, p, q);
auto& m = p.manager();
unsigned sz = m.power_of_2();
op_constraint_args const args(op_constraint::code::and_op, p, q);
auto it = m_dedup.op_constraint_expr.find_iterator(args);
if (it != m_dedup.op_constraint_expr.end())
return m.mk_var(it->m_value);
unsigned sz = m.power_of_2();
pdd r = m.mk_var(s.add_var(sz));
m_dedup.op_constraint_expr.insert(args, r.var());
s.assign_eh(band(p, q, r), null_dependency);
return r;
}