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initial overflow test

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-12-09 14:39:00 -08:00
parent 99e2247ccb
commit a4fc63c542
6 changed files with 47 additions and 8 deletions
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3
src/math/polysat/constraint.cpp
View file

@ -202,6 +202,9 @@ namespace polysat {
return ~ule(b, a);
}
signed_constraint constraint_manager::mul_ovfl(pdd const& a, pdd const& b) {
return { dedup(alloc(mul_ovfl_constraint, *this, a, b)), true };
}
// To do signed comparison of bitvectors, flip the msb and do unsigned comparison:

1
src/math/polysat/constraint.h
View file

@ -94,6 +94,7 @@ namespace polysat {
signed_constraint ult(pdd const& a, pdd const& b);
signed_constraint sle(pdd const& a, pdd const& b);
signed_constraint slt(pdd const& a, pdd const& b);
signed_constraint mul_ovfl(pdd const& p, pdd const& q);
constraint *const* begin() const { return m_constraints.data(); }
constraint *const* end() const { return m_constraints.data() + m_constraints.size(); }

20
src/math/polysat/mul_ovfl_constraint.cpp
View file

@ -18,7 +18,6 @@ namespace polysat {
mul_ovfl_constraint::mul_ovfl_constraint(constraint_manager& m, pdd const& p, pdd const& q):
constraint(m, ckind_t::mul_ovfl_t), m_p(p), m_q(q) {
simplify();
m_vars.append(m_p.free_vars());
for (auto v : m_q.free_vars())
@ -33,6 +32,8 @@ namespace polysat {
m_p = 0;
return;
}
if (m_p.index() > m_q.index())
std::swap(m_p, m_q);
}
std::ostream& mul_ovfl_constraint::display(std::ostream& out, lbool status) const {
@ -104,8 +105,6 @@ namespace polysat {
* TODO optimizations:
* if p is constant, q variable, update viable for q
*
* Use bounds on variables in p instead of current assignment as premise.
* This is a more general lemma
*/
bool mul_ovfl_constraint::narrow_bound(solver& s, bool is_positive,
pdd const& p0, pdd const& q0, pdd const& p, pdd const& q) {
@ -118,22 +117,31 @@ namespace polysat {
// p * q >= max + 1 <=> q >= (max + 1)/p <=> q >= ceil((max+1)/p)
auto bound = ceil((max + 1) / p.val());
//
// the clause that explains bound <= q or bound > q
//
// Ovfl(p, q) & p <= p.val() => q >= bound
// ~Ovfl(p, q) & p >= p.val() => q < bound
// ~Ovfl(p, q) & p >= p.val() => q < bound
//
signed_constraint sc(this, is_positive);
signed_constraint premise = is_positive ? s.ule(p0, p.val()) : s.ule(p.val(), p0);
signed_constraint conseq = is_positive ? s.ule(bound, q0) : s.ult(q0, bound);
SASSERT(premise.is_currently_false(s));
//std::cout << premise << "\n";
//std::cout << sc << "\n";
//std::cout << conseq << "\n";
//std::cout << "Already true " << conseq.is_currently_true(s) << "\n";
SASSERT(premise.is_currently_true(s));
clause_builder cb(s);
cb.push_new(~sc);
cb.push_new(~premise);
cb.push_new(conseq);
clause_ref just = cb.build();
s.assign_propagate(conseq.blit(), *just);
s.add_lemma(*just);
s.propagate();
SASSERT(s.m_bvars.is_true(conseq.blit()));
return true;
}

10
src/math/polysat/solver.h
View file

@ -289,6 +289,8 @@ namespace polysat {
signed_constraint ult(rational const& p, pdd const& q) { return ult(q.manager().mk_val(p), q); }
signed_constraint sle(pdd const& p, pdd const& q) { return m_constraints.sle(p, q); }
signed_constraint slt(pdd const& p, pdd const& q) { return m_constraints.slt(p, q); }
signed_constraint mul_ovfl(pdd const& p, pdd const& q) { return m_constraints.mul_ovfl(p, q); }
signed_constraint mul_ovfl(rational const& p, pdd const& q) { return mul_ovfl(q.manager().mk_val(p), q); }
/** Create and activate polynomial constraints. */
@ -298,6 +300,8 @@ namespace polysat {
void add_ult(pdd const& p, pdd const& q, unsigned dep = null_dependency) { assign_eh(ult(p, q), dep); }
void add_sle(pdd const& p, pdd const& q, unsigned dep = null_dependency) { assign_eh(sle(p, q), dep); }
void add_slt(pdd const& p, pdd const& q, unsigned dep = null_dependency) { assign_eh(slt(p, q), dep); }
void add_noovfl(pdd const& p, pdd const& q, unsigned dep = null_dependency) { assign_eh(~mul_ovfl(p, q), dep); }
void add_ovfl(pdd const& p, pdd const& q, unsigned dep = null_dependency) { assign_eh(mul_ovfl(p, q), dep); }
void add_ule(pdd const& p, rational const& q, unsigned dep = null_dependency) { add_ule(p, p.manager().mk_val(q), dep); }
void add_ule(rational const& p, pdd const& q, unsigned dep = null_dependency) { add_ule(q.manager().mk_val(p), q, dep); }
@ -307,7 +311,11 @@ namespace polysat {
void add_ult(rational const& p, pdd const& q, unsigned dep = null_dependency) { add_ult(q.manager().mk_val(p), q, dep); }
void add_ult(pdd const& p, unsigned q, unsigned dep = null_dependency) { add_ult(p, rational(q), dep); }
void add_ult(unsigned p, pdd const& q, unsigned dep = null_dependency) { add_ult(rational(p), q, dep); }
void add_noovfl(pdd const& p, rational const& q, unsigned dep = null_dependency) { add_noovfl(p, p.manager().mk_val(q), dep); }
void add_noovfl(rational const& p, pdd const& q, unsigned dep = null_dependency) { add_noovfl(q, p, dep); }
void add_noovfl(pdd const& p, unsigned q, unsigned dep = null_dependency) { add_noovfl(p, rational(q), dep); }
void add_noovfl(unsigned p, pdd const& q, unsigned dep = null_dependency) { add_noovfl(q, p, dep); }
/**
* Activate the constraint corresponding to the given boolean variable.
* Note: to deactivate, use push/pop.

2
src/math/polysat/viable.cpp
View file

@ -197,8 +197,8 @@ namespace polysat {
rational lambda_l = floor(coeff_val / e->coeff);
lo = val - lambda_l;
}
SASSERT(hi <= s.var2pdd(v).max_value());
LOG("forbidden interval " << e->interval << " - " << val << " " << coeff_val << " [" << lo << ", " << hi << "[");
SASSERT(hi <= max_value);
entry* ne = alloc_entry();
ne->src = e->src;
ne->side_cond = e->side_cond;

19
src/test/polysat.cpp
View file

@ -940,6 +940,22 @@ namespace polysat {
}
}
static void test_quot_rem(unsigned bw = 32) {
scoped_solver s(__func__);
auto a = s.var(s.add_var(bw));
auto quot = s.var(s.add_var(bw));
auto rem = s.var(s.add_var(bw));
auto x = a * 123;
auto y = 123;
// quot = udiv(a*123, 123)
s.add_eq(quot * y + rem - x);
s.add_diseq(a - quot);
s.add_noovfl(quot, y);
// s.add_ult(rem, x);
s.check();
s.expect_sat();
}
// Goal: we probably mix up polysat variables and PDD variables at several points; try to uncover such cases
// NOTE: actually, add_var seems to keep them in sync, so this is not an issue at the moment (but we should still test it later)
@ -1065,6 +1081,9 @@ namespace polysat {
void tst_polysat() {
polysat::test_quot_rem();
return;
polysat::test_ineq_axiom1();
polysat::test_ineq_axiom2();
polysat::test_ineq_axiom3();