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better behavior on disequality and branch selection (#4605)
* better behavior on disequality and branch selection Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com> * fix loop Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
GitHub
parent
e0d4669116
commit
3f862cb2ee
5 changed files with 52 additions and 80 deletions
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@ -670,8 +670,8 @@ bool theory_seq::branch_binary_variable(eq const& e) {
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if (lenX <= rational(ys.size())) {
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expr_ref_vector Ys(m);
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Ys.append(ys.size(), ys.c_ptr());
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branch_unit_variable(e.dep(), x, Ys);
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return true;
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if (branch_unit_variable(e.dep(), x, Ys))
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return true;
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}
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expr_ref le(m_autil.mk_le(mk_len(x), m_autil.mk_int(ys.size())), m);
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literal lit = mk_literal(le);
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@ -698,13 +698,13 @@ bool theory_seq::branch_binary_variable(eq const& e) {
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bool theory_seq::branch_unit_variable() {
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bool result = false;
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for (auto const& e : m_eqs) {
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if (is_unit_eq(e.ls(), e.rs())) {
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branch_unit_variable(e.dep(), e.ls()[0], e.rs());
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if (is_unit_eq(e.ls(), e.rs()) &&
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branch_unit_variable(e.dep(), e.ls()[0], e.rs())) {
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result = true;
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break;
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}
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else if (is_unit_eq(e.rs(), e.ls())) {
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branch_unit_variable(e.dep(), e.rs()[0], e.ls());
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if (is_unit_eq(e.rs(), e.ls()) &&
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branch_unit_variable(e.dep(), e.rs()[0], e.ls())) {
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result = true;
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break;
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}
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@ -713,38 +713,41 @@ bool theory_seq::branch_unit_variable() {
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return result;
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}
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void theory_seq::branch_unit_variable(dependency* dep, expr* X, expr_ref_vector const& units) {
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bool theory_seq::branch_unit_variable(dependency* dep, expr* X, expr_ref_vector const& units) {
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SASSERT(is_var(X));
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rational lenX;
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if (!get_length(X, lenX)) {
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TRACE("seq", tout << "enforce length on " << mk_bounded_pp(X, m, 2) << "\n";);
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add_length_to_eqc(X);
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return;
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return true;
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}
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if (lenX > rational(units.size())) {
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expr_ref le(m_autil.mk_le(mk_len(X), m_autil.mk_int(units.size())), m);
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TRACE("seq", tout << "propagate length on " << mk_bounded_pp(X, m, 2) << "\n";);
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propagate_lit(dep, 0, nullptr, mk_literal(le));
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return;
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return true;
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}
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SASSERT(lenX.is_unsigned());
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unsigned lX = lenX.get_unsigned();
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if (lX == 0) {
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TRACE("seq", tout << "set empty length " << mk_bounded_pp(X, m, 2) << "\n";);
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set_empty(X);
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return true;
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}
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else {
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literal lit = mk_eq(m_autil.mk_int(lX), mk_len(X), false);
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if (l_true == ctx.get_assignment(lit)) {
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expr_ref R = mk_concat(lX, units.c_ptr(), m.get_sort(X));
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propagate_eq(dep, lit, X, R);
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TRACE("seq", tout << "propagate " << mk_pp(X, m) << " " << R << "\n";);
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}
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else {
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TRACE("seq", tout << "set phase " << mk_pp(X, m) << "\n";);
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ctx.mark_as_relevant(lit);
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ctx.force_phase(lit);
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}
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literal lit = mk_eq(m_autil.mk_int(lX), mk_len(X), false);
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switch (ctx.get_assignment(lit)) {
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case l_true: {
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expr_ref R = mk_concat(lX, units.c_ptr(), m.get_sort(X));
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return propagate_eq(dep, lit, X, R);
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}
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case l_undef:
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TRACE("seq", tout << "set phase " << mk_pp(X, m) << "\n";);
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ctx.mark_as_relevant(lit);
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ctx.force_phase(lit);
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return true;
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default:
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return false;
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}
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}
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@ -1135,13 +1138,11 @@ bool theory_seq::branch_variable_eq(eq const& e) {
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TRACE("seq", tout << s << " " << id << ": " << e.ls() << " = " << e.rs() << "\n";);
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bool found = find_branch_candidate(s, e.dep(), e.ls(), e.rs());
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insert_branch_start(2*id, s);
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if (found) {
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return true;
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if (!found) {
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s = find_branch_start(2*id + 1);
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found = find_branch_candidate(s, e.dep(), e.rs(), e.ls());
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insert_branch_start(2*id + 1, s);
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}
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s = find_branch_start(2*id + 1);
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found = find_branch_candidate(s, e.dep(), e.rs(), e.ls());
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insert_branch_start(2*id + 1, s);
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return found;
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}
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@ -1173,7 +1174,7 @@ bool theory_seq::find_branch_candidate(unsigned& start, dependency* dep, expr_re
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expr_ref v0(m);
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v0 = m_util.str.mk_empty(m.get_sort(l));
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if (can_be_equal(ls.size() - 1, ls.c_ptr() + 1, rs.size(), rs.c_ptr())) {
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if (l_false != assume_equality(l, v0)) {
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if (assume_equality(l, v0)) {
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TRACE("seq", tout << mk_pp(l, m) << " " << v0 << "\n";);
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return true;
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}
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@ -1189,7 +1190,7 @@ bool theory_seq::find_branch_candidate(unsigned& start, dependency* dep, expr_re
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continue;
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}
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v0 = mk_concat(j + 1, rs.c_ptr());
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if (l_false != assume_equality(l, v0)) {
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if (assume_equality(l, v0)) {
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TRACE("seq", tout << mk_pp(l, m) << " " << v0 << "\n";);
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++start;
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return true;
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@ -1212,7 +1213,7 @@ bool theory_seq::find_branch_candidate(unsigned& start, dependency* dep, expr_re
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for (literal lit : lits) {
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switch (ctx.get_assignment(lit)) {
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case l_true: break;
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case l_false: start = 0; return true;
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case l_false: start = 0; return false;
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case l_undef: ctx.mark_as_relevant(lit); ctx.force_phase(~lit); start = 0; return true;
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}
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}
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@ -1253,42 +1254,39 @@ bool theory_seq::can_be_equal(unsigned szl, expr* const* ls, unsigned szr, expr*
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}
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lbool theory_seq::assume_equality(expr* l, expr* r) {
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bool theory_seq::assume_equality(expr* l, expr* r) {
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if (m_exclude.contains(l, r)) {
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return l_false;
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return false;
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}
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expr_ref eq(m.mk_eq(l, r), m);
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m_rewrite(eq);
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if (m.is_true(eq)) {
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return l_true;
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return false;
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}
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if (m.is_false(eq)) {
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return l_false;
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return false;
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}
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enode* n1 = ensure_enode(l);
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enode* n2 = ensure_enode(r);
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if (n1->get_root() == n2->get_root()) {
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TRACE("seq", tout << mk_pp(l, m) << " = " << mk_pp(r, m) << " roots eq\n";);
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return l_true;
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return false;
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}
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if (ctx.is_diseq(n1, n2)) {
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TRACE("seq", tout << mk_pp(l, m) << " = " << mk_pp(r, m) << " is_diseq\n";);
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return l_false;
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}
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if (false && ctx.is_diseq_slow(n1, n2)) {
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return l_false;
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return false;
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}
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ctx.mark_as_relevant(n1);
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ctx.mark_as_relevant(n2);
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if (!ctx.assume_eq(n1, n2)) {
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TRACE("seq", tout << mk_pp(l, m) << " = " << mk_pp(r, m) << " can't assume\n";);
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return l_false;
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return false;
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}
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lbool res = ctx.get_assignment(mk_eq(l, r, false));
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TRACE("seq", tout << mk_pp(l, m) << " = " << mk_pp(r, m) << " literal assigned " << res << "\n";);
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return res;
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return res != l_false;
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}
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@ -1363,14 +1361,9 @@ bool theory_seq::check_length_coherence(expr* e) {
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bool theory_seq::check_length_coherence0(expr* e) {
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if (is_var(e) && m_rep.is_root(e)) {
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expr_ref emp(m_util.str.mk_empty(m.get_sort(e)), m);
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lbool r = l_false;
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bool p = propagate_length_coherence(e);
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if (!p) {
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r = assume_equality(e, emp);
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}
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if (p || r != l_false) {
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if (p || assume_equality(e, emp)) {
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if (!ctx.at_base_level()) {
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m_trail_stack.push(push_replay(alloc(replay_length_coherence, m, e)));
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}
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