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register unhandled expressions

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2020-06-12 16:12:24 -07:00
parent 2613f74baa
commit 41430cd128
5 changed files with 63 additions and 25 deletions
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34
src/ast/rewriter/seq_rewriter.cpp
View file

@ -2181,16 +2181,16 @@ expr_ref seq_rewriter::re_predicate(expr* cond, sort* seq_sort) {
return re_and(cond, re_with_empty);
}
expr_ref seq_rewriter::is_nullable_rec(expr* r) {
expr_ref seq_rewriter::is_nullable(expr* r) {
expr_ref result(m_op_cache.find(_OP_RE_IS_NULLABLE, r, nullptr), m());
if (!result) {
result = is_nullable(r);
result = is_nullable_rec(r);
m_op_cache.insert(_OP_RE_IS_NULLABLE, r, nullptr, result);
}
return result;
}
expr_ref seq_rewriter::is_nullable(expr* r) {
expr_ref seq_rewriter::is_nullable_rec(expr* r) {
SASSERT(m_util.is_re(r) || m_util.is_seq(r));
expr* r1 = nullptr, *r2 = nullptr, *cond = nullptr;
sort* seq_sort = nullptr;
@ -2199,14 +2199,14 @@ expr_ref seq_rewriter::is_nullable(expr* r) {
expr_ref result(m());
if (re().is_concat(r, r1, r2) ||
re().is_intersection(r, r1, r2)) {
m_br.mk_and(is_nullable_rec(r1), is_nullable_rec(r2), result);
m_br.mk_and(is_nullable(r1), is_nullable(r2), result);
}
else if (re().is_union(r, r1, r2)) {
m_br.mk_or(is_nullable_rec(r1), is_nullable_rec(r2), result);
m_br.mk_or(is_nullable(r1), is_nullable(r2), result);
}
else if (re().is_diff(r, r1, r2)) {
m_br.mk_not(is_nullable_rec(r2), result);
m_br.mk_and(result, is_nullable_rec(r1), result);
m_br.mk_not(is_nullable(r2), result);
m_br.mk_and(result, is_nullable(r1), result);
}
else if (re().is_star(r) ||
re().is_opt(r) ||
@ -2225,22 +2225,22 @@ expr_ref seq_rewriter::is_nullable(expr* r) {
(re().is_loop(r, r1, lo) && lo > 0) ||
(re().is_loop(r, r1, lo, hi) && lo > 0) ||
(re().is_reverse(r, r1))) {
result = is_nullable_rec(r1);
result = is_nullable(r1);
}
else if (re().is_complement(r, r1)) {
m_br.mk_not(is_nullable_rec(r1), result);
m_br.mk_not(is_nullable(r1), result);
}
else if (re().is_to_re(r, r1)) {
result = is_nullable_rec(r1);
result = is_nullable(r1);
}
else if (m().is_ite(r, cond, r1, r2)) {
result = m().mk_ite(cond, is_nullable_rec(r1), is_nullable_rec(r2));
result = m().mk_ite(cond, is_nullable(r1), is_nullable(r2));
}
else if (m_util.is_re(r, seq_sort)) {
result = re().mk_in_re(str().mk_empty(seq_sort), r);
}
else if (str().is_concat(r, r1, r2)) {
m_br.mk_and(is_nullable_rec(r1), is_nullable_rec(r2), result);
m_br.mk_and(is_nullable(r1), is_nullable(r2), result);
}
else if (str().is_empty(r)) {
result = m().mk_true();
@ -2574,7 +2574,17 @@ expr_ref seq_rewriter::mk_derivative_rec(expr* ele, expr* r) {
return mk_empty();
}
else {
#if 0
hd = str().mk_nth_i(r1, m_autil.mk_int(0));
tl = str().mk_substr(r1, m_autil.mk_int(1), m_autil.mk_sub(str().mk_length(r1), m_autil.mk_int(1)));
result =
m().mk_ite(m_br.mk_eq_rw(r1, str().mk_empty(m().get_sort(r1))),
mk_empty(),
re_and(m_br.mk_eq_rw(ele, hd), re().mk_to_re(tl)));
return result;
#else
return expr_ref(re().mk_derivative(ele, r), m());
#endif
}
}
else if (re().is_reverse(r, r1) && re().is_to_re(r1, r2)) {

30
src/smt/seq_regex.cpp
View file

@ -101,7 +101,7 @@ namespace smt {
expr* e = ctx.bool_var2expr(lit.var());
VERIFY(str().is_in_re(e, s, r));
TRACE("seq", tout << "propagate " << mk_pp(e, m) << "\n";);
TRACE("seq", tout << "propagate " << lit.sign() << " " << mk_pp(e, m) << "\n";);
// convert negative negative membership literals to positive
// ~(s in R) => s in C(R)
@ -109,6 +109,10 @@ namespace smt {
expr_ref fml(re().mk_in_re(s, re().mk_complement(r)), m);
rewrite(fml);
literal nlit = th.mk_literal(fml);
if (lit == nlit) {
// is-nullable doesn't simplify for regexes with uninterpreted subterms
th.add_unhandled_expr(fml);
}
th.propagate_lit(nullptr, 1, &lit, nlit);
return;
}
@ -138,6 +142,8 @@ namespace smt {
expr_ref acc = sk().mk_accept(s, zero, r);
literal acc_lit = th.mk_literal(acc);
TRACE("seq", tout << "propagate " << acc << "\n";);
th.propagate_lit(nullptr, 1, &lit, acc_lit);
}
@ -177,7 +183,7 @@ namespace smt {
if (block_unfolding(lit, idx))
return true;
propagate_nullable(lit, e, s, idx, r);
propagate_nullable(lit, s, idx, r);
return propagate_derivative(lit, e, s, i, idx, r);
}
@ -187,9 +193,21 @@ namespace smt {
(accept s i r) => len(s) >= i
(accept s i r) & ~nullable(r) => len(s) >= i + 1
evaluate nullable(r):
nullable(r) := true -> propagate: (accept s i r) => len(s) >= i
nullable(r) := false -> propagate: (accept s i r) => len(s) >= i + 1
Otherwise:
propagate: (accept s i r) => len(s) >= i
evaluate len(s) <= i:
len(s) <= i := undef -> axiom: (accept s i r) & len(s) <= i => nullable(r)
len(s) <= i := true -> propagate: (accept s i r) & len(s) <= i => nullable(r)
len(s) <= i := false -> noop.
*/
void seq_regex::propagate_nullable(literal lit, expr* e, expr* s, unsigned idx, expr* r) {
void seq_regex::propagate_nullable(literal lit, expr* s, unsigned idx, expr* r) {
expr_ref is_nullable = seq_rw().is_nullable(r);
rewrite(is_nullable);
literal len_s_ge_i = th.m_ax.mk_ge(th.mk_len(s), idx);
@ -200,14 +218,16 @@ namespace smt {
th.propagate_lit(nullptr, 1, &lit, th.m_ax.mk_ge(th.mk_len(s), idx + 1));
}
else {
literal is_nullable_lit = th.mk_literal(is_nullable);
ctx.mark_as_relevant(is_nullable_lit);
literal len_s_le_i = th.m_ax.mk_le(th.mk_len(s), idx);
switch (ctx.get_assignment(len_s_le_i)) {
case l_undef:
th.add_axiom(~lit, ~len_s_le_i, th.mk_literal(is_nullable));
th.add_axiom(~lit, ~len_s_le_i, is_nullable_lit);
break;
case l_true: {
literal lits[2] = { lit, len_s_le_i };
th.propagate_lit(nullptr, 2, lits, th.mk_literal(is_nullable));
th.propagate_lit(nullptr, 2, lits, is_nullable_lit);
break;
}
case l_false:

4
src/smt/seq_regex.h
View file

@ -59,7 +59,7 @@ namespace smt {
bool block_unfolding(literal lit, unsigned i);
void propagate_nullable(literal lit, expr* e, expr* s, unsigned idx, expr* r);
void propagate_nullable(literal lit, expr* s, unsigned idx, expr* r);
bool propagate_derivative(literal lit, expr* e, expr* s, expr* i, unsigned idx, expr* r);
@ -99,7 +99,7 @@ namespace smt {
void propagate_eq(expr* r1, expr* r2);
void propagate_ne(expr* r1, expr* r2);
void propagate_is_non_empty(literal lit);
void propagate_is_empty(literal lit);

19
src/smt/theory_seq.cpp
View file

@ -2878,8 +2878,11 @@ literal theory_seq::mk_simplified_literal(expr * _e) {
literal theory_seq::mk_literal(expr* _e) {
expr_ref e(_e, m);
ensure_enode(e);
return ctx.get_literal(e);
bool is_not = m.is_not(_e, _e);
ensure_enode(_e);
literal lit = ctx.get_literal(_e);
if (is_not) lit.neg();
return lit;
}
literal theory_seq::mk_seq_eq(expr* a, expr* b) {
@ -3338,10 +3341,14 @@ void theory_seq::relevant_eh(app* n) {
m_util.str.is_from_code(n) ||
m_util.str.is_to_code(n) ||
m_util.str.is_is_digit(n)) {
if (!m_unhandled_expr) {
ctx.push_trail(value_trail<context, expr*>(m_unhandled_expr));
m_unhandled_expr = n;
}
add_unhandled_expr(n);
}
}
void theory_seq::add_unhandled_expr(expr* n) {
if (!m_unhandled_expr) {
ctx.push_trail(value_trail<context, expr*>(m_unhandled_expr));
m_unhandled_expr = n;
}
}

1
src/smt/theory_seq.h
View file

@ -506,6 +506,7 @@ namespace smt {
bool set_empty(expr* x);
bool is_complex(eq const& e);
lbool regex_are_equal(expr* r1, expr* r2);
void add_unhandled_expr(expr* e);
bool check_extensionality();
bool check_contains();