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fix boundary cases reported by Clemens

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This commit is contained in:
Nikolaj Bjorner 2021-07-15 13:43:13 +02:00
parent 79c261736b
commit 0e066fef1f
1 changed files with 23 additions and 15 deletions
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38
src/ast/rewriter/seq_axioms.cpp
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@ -776,26 +776,27 @@ namespace seq {
rational pow(1);
for (unsigned i = 0; i < k; ++i)
pow *= 10;
if (k == 0) {
ge10k = m.mk_true();
}
else {
ge10k = bv.mk_ule(bv.mk_numeral(pow, bv_sort), b);
}
ge10k = bv.mk_ule(bv.mk_numeral(pow, bv_sort), b);
ge10k1 = bv.mk_ule(bv.mk_numeral(pow * 10, bv_sort), b);
unsigned sz = bv.get_bv_size(b);
expr_ref_vector es(m);
expr_ref bb(b, m), ten(bv.mk_numeral(10, sz), m);
pow = 1;
rational p(1);
for (unsigned i = 0; i <= k; ++i) {
if (pow > 1)
bb = bv.mk_bv_udiv(b, bv.mk_numeral(pow, bv_sort));
if (p > 1)
bb = bv.mk_bv_udiv(b, bv.mk_numeral(p, bv_sort));
es.push_back(seq.str.mk_unit(m_sk.mk_ubv2ch(bv.mk_bv_urem(bb, ten))));
pow *= 10;
p *= 10;
}
es.reverse();
eq = m.mk_eq(seq.str.mk_ubv2s(b), seq.str.mk_concat(es, seq.str.mk_string_sort()));
add_clause(~ge10k, ge10k1, eq);
SASSERT(pow < rational::power_of_two(sz));
if (k == 0)
add_clause(ge10k1, eq);
else if (pow * 10 >= rational::power_of_two(sz))
add_clause(~ge10k, eq);
else
add_clause(~ge10k, ge10k1, eq);
}
/*
@ -810,12 +811,19 @@ namespace seq {
rational pow(1);
for (unsigned i = 1; i < k; ++i)
pow *= 10;
if (pow * 10 >= rational::power_of_two(sz))
return; // TODO: add conflict when k is too large or avoid overflow bounds and limits
expr_ref len(seq.str.mk_length(seq.str.mk_ubv2s(b)), m);
if (pow >= rational::power_of_two(sz)) {
expr_ref ge(a.mk_ge(len, a.mk_int(k)), m);
add_clause(~ge);
return;
}
ge10k = bv.mk_ule(bv.mk_numeral(pow, bv_sort), b);
ge10k1 = bv.mk_ule(bv.mk_numeral(pow * 10, bv_sort), b);
eq = m.mk_eq(seq.str.mk_length(seq.str.mk_ubv2s(b)), a.mk_int(k));
add_clause(~eq, ~ge10k1);
eq = m.mk_eq(len, a.mk_int(k));
if (pow * 10 < rational::power_of_two(sz))
add_clause(~eq, ~ge10k1);
if (k > 1)
add_clause(~eq, ge10k);
}