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patch seq theory using purification to avoid unsoundness caused by interaction with canonization and rewriting

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-02-14 17:40:41 -08:00
parent 2db2767e7a
commit 70b4822571
6 changed files with 45 additions and 42 deletions
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38
src/smt/theory_seq.cpp
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@ -2493,14 +2493,14 @@ void theory_seq::propagate() {
m_regex.propagate();
while (m_axioms_head < m_axioms.size() && !ctx.inconsistent()) {
expr_ref e(m);
e = m_axioms[m_axioms_head].get();
e = m_axioms.get(m_axioms_head);
deque_axiom(e);
++m_axioms_head;
}
while (!m_replay.empty() && !ctx.inconsistent()) {
apply* app = m_replay[m_replay.size() - 1];
TRACE("seq", tout << "replay at level: " << ctx.get_scope_level() << "\n";);
(*app)(*this);
apply& app = *m_replay[m_replay.size() - 1];
app(*this);
m_replay.pop_back();
}
if (m_new_solution) {
@ -2540,7 +2540,7 @@ void theory_seq::deque_axiom(expr* n) {
m_ax.add_replace_axiom(n);
}
else if (m_util.str.is_extract(n)) {
m_ax.add_extract_axiom(n);
m_ax.add_extract_axiom(purify(n));
}
else if (m_util.str.is_at(n)) {
m_ax.add_at_axiom(n);
@ -2579,6 +2579,32 @@ void theory_seq::deque_axiom(expr* n) {
}
}
expr_ref theory_seq::purify(expr* e) {
app* a = to_app(e);
expr_ref_vector args(m);
bool has_fresh = false;
for (expr* arg : *a) {
expr_ref tmp(m);
m_rewrite(arg, tmp);
if (arg != tmp) {
has_fresh = true;
tmp = m.mk_fresh_const("purify", arg->get_sort());
enode* n1 = ctx.get_enode(arg);
enode* n2 = ensure_enode(tmp);
justification* js = ctx.mk_justification(
ext_theory_eq_propagation_justification(
get_id(), ctx.get_region(), 0, nullptr, 0, nullptr, n1, n2));
ctx.assign_eq(n1, n2, eq_justification(js));
}
args.push_back(tmp);
}
if (has_fresh)
return expr_ref(m.mk_app(a->get_decl(), args), m);
return expr_ref(a, m);
}
expr_ref theory_seq::add_elim_string_axiom(expr* n) {
zstring s;
TRACE("seq", tout << mk_pp(n, m) << "\n";);
@ -2609,9 +2635,7 @@ expr_ref theory_seq::mk_add(expr* a, expr* b) {
}
expr_ref theory_seq::mk_len(expr* s) {
expr_ref result(m_util.str.mk_length(s), m);
m_rewrite(result);
return result;
return m_seq_rewrite.mk_length(s);
}