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fix fourth bug produced by repros by Mark Dunlop

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2019-01-27 18:11:18 -08:00
parent 1297eeb817
commit 94dae2da3a
6 changed files with 36 additions and 20 deletions
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15
src/smt/theory_seq.cpp
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@ -2905,17 +2905,26 @@ bool theory_seq::get_length(expr* e, expr_ref& len, literal_vector& lits) {
TRACE("seq", ctx.display_literals_verbose(tout, 2, _lits); tout << "\n";);
}
else if (is_skolem(m_tail, e)) {
// e = tail(s, l), len(s) > l =>
// len(tail(s, l)) = len(s) - l - 1
// e = tail(s, l), len(s) > l => len(tail(s, l)) = len(s) - l - 1
// e = tail(s, l), len(s) <= l => len(tail(s, l)) = 0
s = to_app(e)->get_arg(0);
l = to_app(e)->get_arg(1);
expr_ref len_s = mk_len(s);
literal len_s_gt_l = mk_simplified_literal(m_autil.mk_ge(mk_sub(len_s, l), m_autil.mk_int(1)));
if (ctx.get_assignment(len_s_gt_l) == l_true) {
switch (ctx.get_assignment(len_s_gt_l)) {
case l_true:
len = mk_sub(len_s, mk_sub(l, m_autil.mk_int(1)));
TRACE("seq", tout << len_s << " " << len << " " << len_s_gt_l << "\n";);
lits.push_back(len_s_gt_l);
return true;
case l_false:
len = m_autil.mk_int(0);
TRACE("seq", tout << len_s << " " << len << " " << len_s_gt_l << "\n";);
lits.push_back(~len_s_gt_l);
return true;
default:
break;
}
}
else if (m_util.str.is_unit(e)) {