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Dedup quot_rem and lshr too

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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
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33
src/math/polysat/solver.cpp
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@ -133,39 +133,6 @@ namespace polysat {
m_free_pvars.del_var_eh(v);
}
std::tuple<pdd, pdd> solver::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?
}
pdd q = m.mk_var(add_var(sz)); // quotient
pdd r = m.mk_var(add_var(sz)); // remainder
// 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
add_eq(a, b * q + r);
add_umul_noovfl(b, q);
add_ule(r, b*q+r);
auto c_eq = eq(b);
add_clause(c_eq, ult(r, b), false);
add_clause(~c_eq, eq(q + 1), false);
return std::tuple<pdd, pdd>(q, r);
}
pdd solver::lshr(pdd const& p, pdd const& q) {
auto& m = p.manager();
unsigned sz = m.power_of_2();
pdd r = m.mk_var(add_var(sz));
assign_eh(m_constraints.lshr(p, q, r), null_dependency);
return r;
}
void solver::assign_eh(signed_constraint c, dependency dep) {
backjump(base_level());
SASSERT(at_base_level());