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Use checked division

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This commit is contained in:
Jakob Rath 2023-03-06 21:39:43 +01:00
parent 5a8c0ce9c0
commit be0d0d5b9b
1 changed files with 12 additions and 10 deletions
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22
src/math/polysat/saturation.cpp
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@ -785,22 +785,31 @@ namespace polysat {
bool saturation::try_mul_eq_bound(pvar x, conflict& core, inequality const& axb_l_y) { bool saturation::try_mul_eq_bound(pvar x, conflict& core, inequality const& axb_l_y) {
set_rule("[x] 2^k*x = 2^k*y & x < 2^N-k => y = x or y >= 2^{N-k}"); set_rule("[x] 2^k*x = 2^k*y & x < 2^N-k => y = x or y >= 2^{N-k}");
auto& m = s.var2pdd(x); auto& m = s.var2pdd(x);
unsigned N = m.power_of_2(); unsigned const N = m.power_of_2();
pdd y = m.zero(); pdd y = m.zero();
pdd a = y, b = y, a2 = y; pdd a = y, b = y, a2 = y;
pdd X = s.var(x); pdd const X = s.var(x);
// Match ax + b <= y with eval(y) = 0
if (!is_AxB_eq_0(x, axb_l_y, a, b, y)) if (!is_AxB_eq_0(x, axb_l_y, a, b, y))
return false; return false;
if (!a.is_val()) if (!a.is_val())
return false; return false;
if (!a.val().is_power_of_two()) if (!a.val().is_power_of_two())
return false; return false;
unsigned k = a.val().trailing_zeros(); unsigned const k = a.val().trailing_zeros();
if (k == 0) if (k == 0)
return false; return false;
// x*2^k = b, x <= a2 < 2^{N-k}
rational const bound = rational::power_of_two(N - k);
b = -b; b = -b;
if (b.leading_coefficient() != a.val()) if (b.leading_coefficient() != a.val())
return false; return false;
pdd Y = m.zero();
if (!b.try_div(b.leading_coefficient(), Y))
return false;
rational Y_val;
if (!s.try_eval(Y, Y_val) || Y_val >= bound)
return false;
for (auto c : core) { for (auto c : core) {
if (!c->is_ule()) if (!c->is_ule())
continue; continue;
@ -809,15 +818,9 @@ namespace polysat {
continue; continue;
if (!a2.is_val()) if (!a2.is_val())
continue; continue;
// x*2^k = b, x <= a2 < 2^{N-k}
rational bound = rational::power_of_two(N - k);
if (i.is_strict() && a2.val() >= bound) if (i.is_strict() && a2.val() >= bound)
continue; continue;
if (!i.is_strict() && a2.val() > bound) if (!i.is_strict() && a2.val() > bound)
continue;
pdd Y = b.div(b.leading_coefficient());
rational Y_val;
if (!s.try_eval(Y, Y_val) || Y_val >= bound)
continue; continue;
signed_constraint le = s.ule(Y, bound - 1); signed_constraint le = s.ule(Y, bound - 1);
m_lemma.reset(); m_lemma.reset();
@ -827,7 +830,6 @@ namespace polysat {
if (propagate(x, core, axb_l_y, s.eq(X, Y))) if (propagate(x, core, axb_l_y, s.eq(X, Y)))
return true; return true;
} }
return false; return false;
} }