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remove unsound simplification in prefix #949

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-03-21 07:40:35 -06:00
parent d58018841e
commit ca4ae171ea
2 changed files with 16 additions and 8 deletions
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17
src/ast/rewriter/seq_rewriter.cpp
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@ -676,6 +676,7 @@ br_status seq_rewriter::mk_seq_prefix(expr* a, expr* b, expr_ref& result) {
bool isc2 = m_util.str.is_string(b, s2);
if (isc1 && isc2) {
result = m().mk_bool_val(s1.prefixof(s2));
TRACE("seq", tout << result << "\n";);
return BR_DONE;
}
if (m_util.str.is_empty(a)) {
@ -689,6 +690,7 @@ br_status seq_rewriter::mk_seq_prefix(expr* a, expr* b, expr_ref& result) {
expr_ref_vector as(m()), bs(m());
if (a1 != b1 && isc1 && isc2) {
TRACE("seq", tout << s1 << " " << s2 << "\n";);
if (s1.length() <= s2.length()) {
if (s1.prefixof(s2)) {
if (a == a1) {
@ -733,26 +735,27 @@ br_status seq_rewriter::mk_seq_prefix(expr* a, expr* b, expr_ref& result) {
m_util.str.get_concat(a, as);
m_util.str.get_concat(b, bs);
unsigned i = 0;
bool all_values = true;
expr_ref_vector eqs(m());
for (; i < as.size() && i < bs.size(); ++i) {
expr* a = as[i].get(), *b = bs[i].get();
if (a == b) {
continue;
}
all_values &= m().is_value(a) && m().is_value(b);
if (all_values) {
result = m().mk_false();
return BR_DONE;
}
if (m_util.str.is_unit(a) && m_util.str.is_unit(b)) {
eqs.push_back(m().mk_eq(a, b));
continue;
}
if (m().is_value(a) && m().is_value(b) && m_util.str.is_string(a) && m_util.str.is_string(b)) {
TRACE("seq", tout << mk_pp(a, m()) << " != " << mk_pp(b, m()) << "\n";);
result = m().mk_false();
return BR_DONE;
}
break;
}
if (i == as.size()) {
result = mk_and(eqs);
TRACE("seq", tout << result << "\n";);
if (m().is_true(result)) {
return BR_DONE;
}
@ -764,6 +767,7 @@ br_status seq_rewriter::mk_seq_prefix(expr* a, expr* b, expr_ref& result) {
eqs.push_back(m().mk_eq(m_util.str.mk_empty(m().get_sort(a)), as[j].get()));
}
result = mk_and(eqs);
TRACE("seq", tout << result << "\n";);
return BR_REWRITE3;
}
if (i > 0) {
@ -771,6 +775,7 @@ br_status seq_rewriter::mk_seq_prefix(expr* a, expr* b, expr_ref& result) {
a = m_util.str.mk_concat(as.size() - i, as.c_ptr() + i);
b = m_util.str.mk_concat(bs.size() - i, bs.c_ptr() + i);
result = m_util.str.mk_prefix(a, b);
TRACE("seq", tout << result << "\n";);
return BR_DONE;
}
else {