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Fix viable entry reduction (case new_lo == new_hi)

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This commit is contained in:
Jakob Rath 2024-03-14 15:09:21 +01:00
parent f6c99585f3
commit 2102db2df8
1 changed files with 45 additions and 33 deletions
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78
src/sat/smt/polysat/viable.cpp
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@ -587,7 +587,7 @@ namespace polysat {
if (m_var != e->var)
result.push_back(offset_claim(m_var, { e->var, 0 }));
for (auto const& sc : e->side_cond) {
auto d = c.propagate(sc, c.explain_weak_eval(sc));
auto d = c.propagate(sc, c.explain_weak_eval(sc), "entry weak eval");
if (c.inconsistent()) {
verbose_stream() << "inconsistent " << d << " " << sc << "\n";
}
@ -603,6 +603,7 @@ namespace polysat {
};
if (last.e->interval.is_full()) {
SASSERT(m_explain_kind == explain_t::none);
explain_entry(last.e);
SASSERT(m_explain.size() == 1);
unmark();
@ -1151,19 +1152,6 @@ namespace polysat {
// hi[w-1:k] + 1 otherwise
//
// Reference: Fig. 1 (dtrim) in BitvectorsMCSAT
//
//
// Suppose new_lo = new_hi
// Then since ne is not full, then lo != hi
// Cases
// lo < hi, 2^k|lo, new_lo = lo / 2^k != new_hi = hi / 2^k
// lo < hi, not 2^k|lo, 2^k|hi, new_lo = lo / 2^k + 1, new_hi = hi / 2^k
// new_lo = new_hi -> empty
// k = 3, lo = 1, hi = 8, new_lo = 1, new_hi = 1
// lo < hi, not 2^k|lo, not 2^k|hi, new_lo = lo / 2^k + 1, new_hi = hi / 2^k + 1
// new_lo = new_hi -> empty
// k = 3, lo = 1, hi = 2, new_lo = 1 div 2^3 + 1 = 1, new_hi = 2 div 2^3 + 1 = 1
// lo > hi
TRACE("bv", display_one(tout << "try to reduce entry: ", ne) << "\n");
pdd const& pdd_lo = ne->interval.lo();
@ -1197,30 +1185,50 @@ namespace polysat {
ne->side_cond.push_back(~cs.eq(hi_eq));
}
//
// If new_lo = new_hi it means that
// mod(ceil (lo / 2^k), 2^w) = mod(ceil (hi / 2^k), 2^w)
//
// If new_lo = new_hi it means that
// mod(ceil(lo / 2^k), 2^(w-k)) = mod(ceil(hi / 2^k), 2^(w-k))
// or
// div (mod(lo + 2^k - 1, 2^w), 2^k) = div (mod(hi + 2^k - 1, 2^w), 2^k)
// div(mod(lo + 2^k - 1, 2^w), 2^k) = div(mod(hi + 2^k - 1, 2^w), 2^k)
// but we also have lo != hi.
// Assume lo < hi
// - it means 2^k does not divide any of [lo, hi[
// so x*2^k cannot be in [lo, hi[
// Assume lo > hi
// - then the constraint is x*2^k not in [lo, 0[, [0, hi[
// - it means 2^k does not divide any of [hi, lo[
// - therefore the interval [lo, hi[ contains all the divisors of 2^k
//
// Cases:
// 0 < lo < hi: empty (2^k does not divide any of [lo, hi[)
// 0 == lo < hi: full
// 0 < hi < lo: full
// 0 == hi < lo: empty
//
if (new_lo == new_hi) {
bool is_empty_ivl;
if (lo < hi) {
ne->side_cond.push_back(cs.ult(pdd_lo, pdd_hi));
if (lo == 0) {
ne->side_cond.push_back(cs.eq(pdd_lo));
is_empty_ivl = false;
}
else {
ne->side_cond.push_back(~cs.eq(pdd_lo));
is_empty_ivl = true;
}
}
else {
SASSERT(hi < lo);
ne->side_cond.push_back(cs.ult(pdd_hi, pdd_lo));
if (hi == 0) {
ne->side_cond.push_back(cs.eq(pdd_hi));
is_empty_ivl = true;
}
else {
ne->side_cond.push_back(~cs.eq(pdd_hi));
is_empty_ivl = false;
}
}
if (is_empty_ivl) {
m_alloc.push_back(ne);
return find_t::multiple;
}
else {
// IF_VERBOSE(0, display_one(verbose_stream() << "full: ", ne) << "\n");
SASSERT(hi < lo);
ne->interval = eval_interval::full();
ne->coeff = 1;
m_explain.reset();
@ -1444,12 +1452,15 @@ namespace polysat {
out << "[" << e->bit_width << "]";
out << " " << e->interval << " ";
}
for (auto const& d : e->deps)
out << d << " ";
if (e->side_cond.size() <= 5)
out << e->side_cond << " ";
if (!e->deps.empty())
out << " deps " << e->deps;
if (e->side_cond.empty())
;
else if (e->side_cond.size() <= 5)
out << " side-conds " << e->side_cond;
else
out << e->side_cond.size() << " side-conditions ";
out << " side-conds " << e->side_cond.size() << " side-conditions";
out << " src ";
unsigned count = 0;
for (const auto& src : e->src) {
++count;
@ -1505,6 +1516,7 @@ namespace polysat {
}
std::ostream& viable::display_explain(std::ostream& out) const {
out << "explain_kind " << m_explain_kind << "\n";
display_state(out);
for (auto const& e : m_explain)
display_one(out << "v" << m_var << "[" << e.e->bit_width << "] := " << e.value << " ", e.e) << "\n";