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add unconstrained elimination for sequences

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This commit is contained in:
Nikolaj Bjorner 2023-03-14 09:23:13 +01:00
parent a0f3727e90
commit d1c7ff1a36
12 changed files with 148 additions and 16 deletions
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36
src/ast/rewriter/seq_rewriter.cpp
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@ -5518,6 +5518,7 @@ bool seq_rewriter::reduce_eq(expr_ref_vector& ls, expr_ref_vector& rs, expr_ref_
reduce_front(ls, rs, eqs) &&
reduce_itos(ls, rs, eqs) &&
reduce_itos(rs, ls, eqs) &&
reduce_value_clash(ls, rs, eqs) &&
reduce_by_length(ls, rs, eqs) &&
reduce_subsequence(ls, rs, eqs) &&
reduce_non_overlap(ls, rs, eqs) &&
@ -5943,6 +5944,41 @@ bool seq_rewriter::reduce_non_overlap(expr_ref_vector& ls, expr_ref_vector& rs,
return true;
}
/**
* partial check for value clash.
* checks that elements that do not occur in
* other sequence are non-values.
* The check could be extended to take non-value
* characters (units) into account.
*/
bool seq_rewriter::reduce_value_clash(expr_ref_vector& ls, expr_ref_vector& rs, expr_ref_pair_vector& eqs) {
ptr_buffer<expr> es;
if (ls.empty() || rs.empty())
return true;
es.append(ls.size(), ls.data());
auto remove = [&](expr* r) {
for (unsigned i = 0; i < es.size(); ++i) {
if (r == es[i]) {
es[i] = es.back();
es.pop_back();
return true;
}
}
return false;
};
auto is_unit_value = [&](expr* r) {
return m().is_value(r) && str().is_unit(r);
};
for (expr* r : rs) {
if (remove(r))
continue;
if (!is_unit_value(r))
return true;
}
return any_of(es, [&](expr* e) { return is_unit_value(e); });
}
bool seq_rewriter::reduce_subsequence(expr_ref_vector& ls, expr_ref_vector& rs, expr_ref_pair_vector& eqs) {
if (ls.size() > rs.size())

1
src/ast/rewriter/seq_rewriter.h
View file

@ -340,6 +340,7 @@ class seq_rewriter {
bool is_sequence(expr* e, expr_ref_vector& seq);
bool is_sequence(eautomaton& aut, expr_ref_vector& seq);
bool get_lengths(expr* e, expr_ref_vector& lens, rational& pos);
bool reduce_value_clash(expr_ref_vector& ls, expr_ref_vector& rs, expr_ref_pair_vector& new_eqs);
bool reduce_back(expr_ref_vector& ls, expr_ref_vector& rs, expr_ref_pair_vector& new_eqs);
bool reduce_front(expr_ref_vector& ls, expr_ref_vector& rs, expr_ref_pair_vector& new_eqs);
void remove_empty_and_concats(expr_ref_vector& es);