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fix #6894

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2023-09-14 16:03:56 -07:00
parent 3aea4ebf42
commit 50d76a2fe3
2 changed files with 60 additions and 11 deletions
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67
src/ast/simplifiers/solve_context_eqs.cpp
View file

@ -243,8 +243,8 @@ namespace euf {
void solve_context_eqs::collect_nested_equalities(dependent_expr const& df, expr_mark& visited, dep_eq_vector& eqs) {
svector<std::tuple<bool,unsigned,expr*>> todo;
todo.push_back({ false, 0, df.fml()});
svector<std::tuple<bool,unsigned,expr*, unsigned>> todo;
todo.push_back({ false, 0, df.fml(), 0});
// even depth is conjunctive context, odd is disjunctive
// when alternating between conjunctive and disjunctive context, increment depth.
@ -255,37 +255,84 @@ namespace euf {
return (0 == depth % 2) ? depth : depth + 1;
};
while (!todo.empty()) {
auto [s, depth, f] = todo.back();
todo.pop_back();
for (unsigned i = 0; i < todo.size(); ++i) {
auto [s, depth, f, p] = todo[i];
if (visited.is_marked(f))
continue;
visited.mark(f, true);
if (s && m.is_and(f)) {
for (auto* arg : *to_app(f))
todo.push_back({ s, inc_or(depth), arg });
todo.push_back({ s, inc_or(depth), arg, i });
}
else if (!s && m.is_or(f)) {
for (auto* arg : *to_app(f))
todo.push_back({ s, inc_or(depth), arg });
todo.push_back({ s, inc_or(depth), arg, i });
}
if (!s && m.is_and(f)) {
for (auto* arg : *to_app(f))
todo.push_back({ s, inc_and(depth), arg });
todo.push_back({ s, inc_and(depth), arg, i });
}
else if (s && m.is_or(f)) {
for (auto* arg : *to_app(f))
todo.push_back({ s, inc_and(depth), arg });
todo.push_back({ s, inc_and(depth), arg, i });
}
else if (m.is_not(f, f))
todo.push_back({ !s, depth, f });
todo.push_back({ !s, depth, f, i });
else if (!s && 1 <= depth) {
unsigned sz = eqs.size();
for (extract_eq* ex : m_solve_eqs.m_extract_plugins) {
ex->set_allow_booleans(false);
ex->get_eqs(dependent_expr(m, f, nullptr, df.dep()), eqs);
ex->set_allow_booleans(true);
}
// prune eqs for solutions that are not safe in df.fml()
for (; sz < eqs.size(); ++sz) {
if (!is_safe_var(eqs[sz].var, i, df.fml(), todo)) {
eqs[sz] = eqs.back();
--sz;
eqs.pop_back();
}
}
}
}
}
bool solve_context_eqs::is_safe_var(expr* x, unsigned i, expr* f, svector<std::tuple<bool,unsigned,expr*,unsigned>> const& todo) {
m_contains_v.reset();
m_todo.push_back(f);
mark_occurs(m_todo, x, m_contains_v);
SASSERT(m_todo.empty());
auto is_parent = [&](unsigned p, unsigned i) {
while (p != i && i != 0) {
auto [_s,_depth, _f, _p] = todo[i];
i = _p;
}
return p == i;
};
// retrieve oldest parent of i whose sign is false
unsigned pi = i;
while (pi != 0) {
auto [s, depth, f, p] = todo[pi];
if (s)
break;
pi = p;
}
// determine if j and j have common conjunctive parent
// for every j in todo.
for (unsigned j = 0; j < todo.size(); ++j) {
auto [s, depth, f, p] = todo[j];
if (i == j || !m_contains_v.is_marked(f))
continue;
if (is_parent(j, i)) // j is a parent if i
continue;
if (is_parent(pi, j)) // pi is a parent of j
continue;
return false;
}
return true;
}
}

4
src/ast/simplifiers/solve_context_eqs.h
View file

@ -45,7 +45,9 @@ namespace euf {
bool contains_conjunctively(expr* f, bool sign, expr* e, signed_expressions& conjuncts);
bool is_conjunction(bool sign, expr* f) const;
void collect_nested_equalities(dependent_expr const& f, expr_mark& visited, dep_eq_vector& eqs);
void collect_nested_equalities(dependent_expr const& f, expr_mark& visited, dep_eq_vector& eqs);
bool is_safe_var(expr* x, unsigned i, expr* f, svector<std::tuple<bool,unsigned,expr*,unsigned>> const& todo);
public: