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cleanup op-defs

This commit is contained in:
Nikolaj Bjorner 2023-12-31 16:47:15 -08:00
parent ff7854f4ea
commit 30b5b3bd15
4 changed files with 76 additions and 183 deletions

View file

@ -534,7 +534,7 @@ namespace polysat {
}
void core::add_axiom(signed_constraint sc) {
void core::add_opdef(signed_constraint sc) {
auto idx = register_constraint(sc, dependency::axiom());
assign_eh(idx, false);
}

View file

@ -92,7 +92,7 @@ namespace polysat {
lbool assign_variable();
void add_axiom(signed_constraint sc);
void add_opdef(signed_constraint sc);
unsigned m_activity_inc = 128;
void inc_activity(pvar v);
@ -124,10 +124,10 @@ namespace polysat {
signed_constraint bit(pdd const& p, unsigned i) { return m_constraints.bit(p, i); }
void lshr(pdd const& a, pdd const& b, pdd const& r) { add_axiom(m_constraints.lshr(a, b, r)); }
void ashr(pdd const& a, pdd const& b, pdd const& r) { add_axiom(m_constraints.ashr(a, b, r)); }
void shl(pdd const& a, pdd const& b, pdd const& r) { add_axiom(m_constraints.shl(a, b, r)); }
void band(pdd const& a, pdd const& b, pdd const& r) { add_axiom(m_constraints.band(a, b, r)); }
void lshr(pdd const& a, pdd const& b, pdd const& r) { add_opdef(m_constraints.lshr(a, b, r)); }
void ashr(pdd const& a, pdd const& b, pdd const& r) { add_opdef(m_constraints.ashr(a, b, r)); }
void shl(pdd const& a, pdd const& b, pdd const& r) { add_opdef(m_constraints.shl(a, b, r)); }
void band(pdd const& a, pdd const& b, pdd const& r) { add_opdef(m_constraints.band(a, b, r)); }
pdd bnot(pdd p) { return -p - 1; }
pdd mul(unsigned n, pdd const* args) { return m_monomials.mk(n, args); }

View file

@ -198,13 +198,28 @@ namespace polysat {
}
void op_constraint::activate(core& c, bool sign, dependency const& dep) {
auto& m = p.manager();
unsigned const N = m.power_of_2();
auto& C = c.cs();
SASSERT(!sign);
switch (m_op) {
case code::and_op:
activate_and(c, dep);
break;
case code::ashr_op:
activate_ashr(c, dep);
c.add_axiom("q >= N & p < 0 -> p <<a q = -1", { ~C.uge(q, N), ~C.slt(p, 0), C.eq(r, m.max_value()) }, false);
c.add_axiom("q >= N & p >= 0 -> p <<a q = 0", { ~C.uge(q, N), ~C.sge(p, 0), C.eq(r) }, false);
c.add_axiom("q = 0 -> p <<a q = p", { ~C.eq(q), C.eq(r, p) }, false);
break;
case code::lshr_op:
c.add_axiom("q >= N -> p <<l q = 0", { ~C.uge(q, N), C.eq(r) }, false);
c.add_axiom("q = 0 -> p <<l q = p", { ~C.eq(q), C.eq(r, p) }, false);
break;
case code::shl_op:
c.add_axiom("q >= N -> p >> q = 0", { ~C.uge(q, N), C.eq(r) }, false);
c.add_axiom("q = 0 -> p >> q = p", { ~C.eq(q), C.eq(r, p) }, false);
break;
case code::inv_op:
break;
default:
break;
@ -312,22 +327,13 @@ namespace polysat {
}
}
void op_constraint::activate_ashr(core& c, dependency const& d) {
auto& m = p.manager();
unsigned const N = m.power_of_2();
auto& C = c.cs();
c.add_axiom("q >= N & p < 0 -> p << q = -1", {~C.uge(q, N), ~C.slt(p, 0), C.eq(r, m.max_value())}, false);
c.add_axiom("q >= N & p >= 0 -> p << q = 0", {~C.uge(q, N), ~C.sge(p, 0), C.eq(r)}, false);
c.add_axiom("q = 0 -> p << q = p", { ~C.eq(q), C.eq(r, p) }, false);
}
void op_constraint::activate_and(core& c, dependency const& d) {
auto x = p, y = q;
auto& C = c.cs();
c.add_axiom("band-mask p&q <= p", { C.ule(r, p) }, false);
c.add_axiom("band-mask p&q <= q", { C.ule(r, q) }, false);
c.add_axiom("p & q <= p", { C.ule(r, p) }, false);
c.add_axiom("p & q <= q", { C.ule(r, q) }, false);
c.add_axiom("p = q -> p & q = p", { ~C.eq(p, q), C.eq(r, p) }, false);
if (x.is_val())
std::swap(x, y);
@ -338,15 +344,15 @@ namespace polysat {
if (!(yv + 1).is_power_of_two())
return;
if (yv == m.max_value())
c.add_axiom("band-mask-true", { C.eq(x, r) }, false);
c.add_axiom("p & 1 = p", { C.eq(x, r) }, false);
else if (yv == 0)
c.add_axiom("band-mask-false", { C.eq(r) }, false);
c.add_axiom("p & 0 = 0", { C.eq(r) }, false);
else {
unsigned N = m.power_of_2();
unsigned k = yv.get_num_bits();
SASSERT(k < N);
rational exp = rational::power_of_two(N - k);
c.add_axiom("band-mask 1", { C.eq(x * exp, r * exp) }, false);
c.add_axiom("(p & 0011)*2^k = p*2^k", { C.eq(x * exp, r * exp) }, false);
}
}
@ -409,10 +415,10 @@ namespace polysat {
auto& C = c.cs();
if (qv.is_val() && qv.val() >= N && rv.is_val() && !rv.is_zero())
c.add_axiom("q >= N -> r = 0", { ~C.ule(N, q), C.eq(r) }, true);
c.add_axiom("q >= N -> p >> q = 0", { ~C.ule(N, q), C.eq(r) }, true);
else if (qv.is_zero() && pv.is_val() && rv.is_val() && rv != pv)
//
c.add_axiom("q = 0 -> r = p", { ~C.eq(q), C.eq(r, p) }, true);
c.add_axiom("q = 0 -> p >> q = p", { ~C.eq(q), C.eq(r, p) }, true);
else if (qv.is_val() && !qv.is_zero() && qv.val() < N && rv.is_val() &&
!rv.is_zero() && rv.val() < rational::power_of_two(qv.val().get_unsigned()))
// q >= k -> r = 0 \/ r >= 2^k (intuitive version)
@ -423,27 +429,25 @@ namespace polysat {
// q = k -> r[i+k] = p[i] for 0 <= i < N - k
for (unsigned i = 0; i < N - k; ++i) {
if (rv.val().get_bit(i + k) && !pv.val().get_bit(i)) {
c.add_axiom("q = k -> r[i+k] = p[i] for 0 <= i < N - k", { ~C.eq(q, k), ~C.bit(r, i + k), C.bit(p, i) }, true);
c.add_axiom("q = k -> p>>q[i+k] = p[i] for 0 <= i < N - k", { ~C.eq(q, k), ~C.bit(r, i + k), C.bit(p, i) }, true);
}
if (!rv.val().get_bit(i + k) && pv.val().get_bit(i)) {
c.add_axiom("q = k -> r[i+k] = p[i] for 0 <= i < N - k", { ~C.eq(q, k), C.bit(r, i + k), ~C.bit(p, i) }, true);
c.add_axiom("q = k -> p>>q[i+k] = p[i] for 0 <= i < N - k", { ~C.eq(q, k), C.bit(r, i + k), ~C.bit(p, i) }, true);
}
}
}
else {
// forward propagation
SASSERT(!(pv.is_val() && qv.is_val() && rv.is_val()));
// LOG(p << " = " << pv << " and " << q << " = " << qv << " yields [<<] " << r << " = " << (qv.val().is_unsigned() ? rational::power_of_two(qv.val().get_unsigned()) * pv.val() : rational::zero()));
if (qv.is_val() && !rv.is_val()) {
rational const& q_val = qv.val();
if (q_val >= N)
// q >= N ==> r = 0
c.add_axiom("shl forward 1", {~C.ule(N, q), C.eq(r)}, true);
if (q_val >= N)
c.add_axiom("q >= N ==> p << q = 0", {~C.ule(N, q), C.eq(r)}, true);
if (pv.is_val()) {
SASSERT(q_val.is_unsigned());
// p = p_val & q = q_val ==> r = p_val * 2^q_val
rational const r_val = pv.val() * rational::power_of_two(q_val.get_unsigned());
c.add_axiom("shl forward 2", {~C.eq(p, pv), ~C.eq(q, qv), C.eq(r, r_val)}, true);
c.add_axiom("p = v1, q = v2, p << q -> v1 << v2", {~C.eq(p, pv), ~C.eq(q, qv), C.eq(r, r_val)}, true);
}
}
}
@ -470,164 +474,54 @@ namespace polysat {
auto& C = c.cs();
if (pv.is_val() && rv.is_val() && rv.val() > pv.val())
c.add_axiom("p&q <= p", { C.ule(r, p) }, true);
c.add_axiom("p & q <= p", { C.ule(r, p) }, true);
else if (qv.is_val() && rv.is_val() && rv.val() > qv.val())
c.add_axiom("p&q <= q", { C.ule(r, q) }, true);
c.add_axiom("p & q <= q", { C.ule(r, q) }, true);
else if (pv.is_val() && qv.is_val() && rv.is_val() && pv == qv && rv != pv)
c.add_axiom("p = q => r = p", { ~C.eq(p, q), C.eq(r, p) }, true);
c.add_axiom("p = q => p & q = p", { ~C.eq(p, q), C.eq(r, p) }, true);
// p = a && q = b ==> r = a & b
else if (pv.is_val() && qv.is_val() && !rv.is_val())
// Just assign by this very weak justification. It will be strengthened in saturation in case of a conflict
c.add_axiom("p = a & q = b => r = a&b", { ~C.eq(p, pv), ~C.eq(q, qv), C.eq(r, bitwise_and(pv.val(), qv.val())) }, true);
else if (pv.is_val() && qv.is_val() && rv.is_val()) {
if (pv.is_max() && qv != rv)
c.add_axiom("p = -1 => r = q", { ~C.eq(p, m.max_value()), C.eq(q, r) }, true);
if (qv.is_max() && pv != rv)
c.add_axiom("q = -1 => r = p", { ~C.eq(q, m.max_value()), C.eq(p, r) }, true);
c.add_axiom("p = -1 => p & q = q", { ~C.eq(p, m.max_value()), C.eq(q, r) }, true);
else if (qv.is_max() && pv != rv)
c.add_axiom("q = -1 => p & q = p", { ~C.eq(q, m.max_value()), C.eq(p, r) }, true);
else {
unsigned const N = m.power_of_2();
unsigned pow;
if ((pv.val() + 1).is_power_of_two(pow)) {
if (rv.is_zero() && !qv.is_zero() && qv.val() <= pv.val())
c.add_axiom("p = 2^k - 1 && p & q = 0 && q != 0 => q >= 2^k", { ~C.eq(p, pv), ~C.eq(r), C.eq(q), C.ule(pv + 1, q) }, true);
else if (rv != qv)
c.add_axiom("p = 2^k - 1 ==> (p&q)*2^{N - k} = q*2^{N - k}", { ~C.eq(p, pv), C.eq(r * rational::power_of_two(N - pow), q * rational::power_of_two(N - pow)) }, true);
}
if ((qv.val() + 1).is_power_of_two(pow)) {
if (rv.is_zero() && !pv.is_zero() && pv.val() <= qv.val())
c.add_axiom("q = 2^k - 1 && p & q = 0 && p != 0 ==> p >= 2^k", { ~C.eq(q, qv), ~C.eq(r), C.eq(p), C.ule(qv + 1, p) }, true);
else if (rv != pv)
c.add_axiom("q = 2^k - 1 ==> (p&q)*2^{N - k} = p*2^{N - k}", { ~C.eq(q, qv), C.eq(r * rational::power_of_two(N - pow), p * rational::power_of_two(N - pow)) }, true);
}
unsigned const N = m.power_of_2();
unsigned pow;
if ((pv.val() + 1).is_power_of_two(pow)) {
if (rv.is_zero() && !qv.is_zero() && qv.val() <= pv.val())
c.add_axiom("p = 2^k - 1 && r = 0 && q != 0 => q >= 2^k", { ~C.eq(p, pv), ~C.eq(r), C.eq(q), C.ule(pv + 1, q) }, true);
if (rv != qv)
c.add_axiom("p = 2^k - 1 ==> r*2^{N - k} = q*2^{N - k}", { ~C.eq(p, pv), C.eq(r * rational::power_of_two(N - pow), q * rational::power_of_two(N - pow)) }, true);
for (unsigned i = 0; i < N; ++i) {
bool pb = pv.val().get_bit(i);
bool qb = qv.val().get_bit(i);
bool rb = rv.val().get_bit(i);
if (rb == (pb && qb))
continue;
if (pb && qb && !rb)
c.add_axiom("p&q[i] = p[i]&q[i]", { ~C.bit(p, i), ~C.bit(q, i), C.bit(r, i) }, true);
else if (!pb && rb)
c.add_axiom("p&q[i] = p[i]&q[i]", { C.bit(p, i), ~C.bit(r, i) }, true);
else if (!qb && rb)
c.add_axiom("p&q[i] = p[i]&q[i]", { C.bit(q, i), ~C.bit(r, i) }, true);
else
UNREACHABLE();
return;
}
}
if ((qv.val() + 1).is_power_of_two(pow)) {
if (rv.is_zero() && !pv.is_zero() && pv.val() <= qv.val())
c.add_axiom("q = 2^k - 1 && r = 0 && p != 0 ==> p >= 2^k", { ~C.eq(q, qv), ~C.eq(r), C.eq(p), C.ule(qv + 1, p) }, true);
//
if (rv != pv)
c.add_axiom("q = 2^k - 1 ==> r*2^{N - k} = p*2^{N - k}", { ~C.eq(q, qv), C.eq(r * rational::power_of_two(N - pow), p * rational::power_of_two(N - pow)) }, true);
}
for (unsigned i = 0; i < N; ++i) {
bool pb = pv.val().get_bit(i);
bool qb = qv.val().get_bit(i);
bool rb = rv.val().get_bit(i);
if (rb == (pb && qb))
continue;
if (pb && qb && !rb)
c.add_axiom("p&q[i] = p[i]&q[i]", { ~C.bit(p, i), ~C.bit(q, i), C.bit(r, i) }, true);
else if (!pb && rb)
c.add_axiom("p&q[i] = p[i]&q[i]", { C.bit(p, i), ~C.bit(r, i) }, true);
else if (!qb && rb)
c.add_axiom("p&q[i] = p[i]&q[i]", { C.bit(q, i), ~C.bit(r, i) }, true);
else
UNREACHABLE();
}
return;
}
// Propagate r if p or q are 0
else if (pv.is_zero() && !rv.is_zero()) // rv not necessarily fully evaluated
c.add_axiom("p = 0 -> p&q = 0", { C.ule(r, p) }, true);
else if (qv.is_zero() && !rv.is_zero()) // rv not necessarily fully evaluated
c.add_axiom("q = 0 -> p&q = 0", { C.ule(r, q) }, true);
// p = a && q = b ==> r = a & b
else if (pv.is_val() && qv.is_val() && !rv.is_val()) {
// Just assign by this very weak justification. It will be strengthened in saturation in case of a conflict
LOG(p << " = " << pv << " and " << q << " = " << qv << " yields [band] " << r << " = " << bitwise_and(pv.val(), qv.val()));
c.add_axiom("p = a & q = b => r = a&b", { ~C.eq(p, pv), ~C.eq(q, qv), C.eq(r, bitwise_and(pv.val(), qv.val())) }, true);
}
}
#if 0
// introduce multiplication constraint and do away with non-linear polynomials in inequalities.
//
// z = x * y
// x = 0 or y = 0 => z = 0
// x = 1 => z = y
// y = 1 => z = y
// ~ovfl(x, y) => z >= x & z >= y
// ~ovfl(x, y) & x > 1 & y > 1 => z > x, z > y
// parity(x) + parity(y) >= N => z = 0
// parity(x) + parity(y) < N => parity(z) = parity(x) + parity(y)
// blast:
// z = sum_i bit(x,i) ? y*2^i : 0
#endif
#if 0
/**
* Produce lemmas for constraint: r == inv p
* p = 0 ==> r = 0
* r = 0 ==> p = 0
* p != 0 ==> odd(r)
* parity(p) >= k ==> p * r >= 2^k
* parity(p) < k ==> p * r <= 2^k - 1
* parity(p) < k ==> r <= 2^(N - k) - 1 (because r is the smallest pseudo-inverse)
*/
clause_ref op_constraint::lemma_inv(solver& s, assignment const& a) {
auto& m = p.manager();
auto pv = a.apply_to(p);
auto rv = a.apply_to(r);
if (eval_inv(pv, rv) == l_true)
return {};
signed_constraint const invc(this, true);
// p = 0 ==> r = 0
if (pv.is_zero())
c.add_axiom(~invc, ~C.eq(p), C.eq(r), true);
// r = 0 ==> p = 0
if (rv.is_zero())
c.add_axiom(~invc, ~C.eq(r), C.eq(p), true);
// forward propagation: p assigned ==> r = pseudo_inverse(eval(p))
// TODO: (later) this should be propagated instead of adding a clause
/*if (pv.is_val() && !rv.is_val())
c.add_axiom(~invc, ~C.eq(p, pv), C.eq(r, pv.val().pseudo_inverse(m.power_of_2())), true);*/
if (!pv.is_val() || !rv.is_val())
return {};
unsigned parity_pv = pv.val().trailing_zeros();
unsigned parity_rv = rv.val().trailing_zeros();
LOG("p: " << p << " := " << pv << " parity " << parity_pv);
LOG("r: " << r << " := " << rv << " parity " << parity_rv);
// p != 0 ==> odd(r)
if (parity_rv != 0)
c.add_axiom("r = inv p & p != 0 ==> odd(r)", {~invc, C.eq(p), s.odd(r)}, true);
pdd prod = p * r;
rational prodv = (pv * rv).val();
// if (prodv != rational::power_of_two(parity_pv))
// verbose_stream() << prodv << " " << rational::power_of_two(parity_pv) << " " << parity_pv << " " << pv << " " << rv << "\n";
unsigned lower = 0, upper = m.power_of_2();
// binary search for the parity (otw. we would have justifications like "parity_at_most(k) && parity_at_least(k)" for at most "k" widths
while (lower + 1 < upper) {
unsigned middle = (upper + lower) / 2;
LOG("Splitting on " << middle);
if (parity_pv >= middle) { // parity at least middle
lower = middle;
LOG("Its in [" << lower << "; " << upper << ")");
// parity(p) >= k ==> p * r >= 2^k
if (prodv < rational::power_of_two(middle))
c.add_axiom("r = inv p & parity(p) >= k ==> p*r >= 2^k",
{~invc, ~s.parity_at_least(p, middle), s.uge(prod, rational::power_of_two(middle))}, false);
// parity(p) >= k ==> r <= 2^(N - k) - 1 (because r is the smallest pseudo-inverse)
rational const max_rv = rational::power_of_two(m.power_of_2() - middle) - 1;
if (rv.val() > max_rv)
c.add_axiom("r = inv p & parity(p) >= k ==> r <= 2^(N - k) - 1",
{~invc, ~s.parity_at_least(p, middle), C.ule(r, max_rv)}, false);
}
else { // parity less than middle
SASSERT(parity_pv < middle);
upper = middle;
LOG("Its in [" << lower << "; " << upper << ")");
// parity(p) < k ==> p * r <= 2^k - 1
if (prodv > rational::power_of_two(middle))
c.add_axiom("r = inv p & parity(p) < k ==> p*r <= 2^k - 1",
{~invc, s.parity_at_least(p, middle), C.ule(prod, rational::power_of_two(middle) - 1)}, false);
}
}
// Why did it evaluate to false in this case?
UNREACHABLE();
return {};
}
#endif
}

View file

@ -68,7 +68,6 @@ namespace polysat {
std::ostream& display(std::ostream& out, char const* eq) const;
void activate_and(core& s, dependency const& d);
void activate_ashr(core& s, dependency const& d);
public:
~op_constraint() override {}