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add binary_merge encoding option

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2019-02-28 08:35:22 -08:00
parent c4ee4ffae4
commit 4c76d43670
6 changed files with 283 additions and 4 deletions
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37
src/ast/rewriter/pb2bv_rewriter.cpp
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@ -161,7 +161,6 @@ struct pb2bv_rewriter::imp {
}
if (m_pb_solver == "segmented") {
expr_ref result(m);
switch (is_le) {
case l_true: return mk_seg_le(k);
case l_false: return mk_seg_ge(k);
@ -169,6 +168,11 @@ struct pb2bv_rewriter::imp {
}
}
if (m_pb_solver == "binary_merge") {
expr_ref result = binary_merge(is_le, k);
if (result) return result;
}
// fall back to divide and conquer encoding.
SASSERT(k.is_pos());
expr_ref zero(m), bound(m);
@ -494,6 +498,37 @@ struct pb2bv_rewriter::imp {
return true;
}
/**
\brief binary merge encoding.
*/
expr_ref binary_merge(lbool is_le, rational const& k) {
expr_ref result(m);
unsigned_vector coeffs;
for (rational const& c : m_coeffs) {
if (c.is_unsigned()) {
coeffs.push_back(c.get_unsigned());
}
else {
return result;
}
}
if (!k.is_unsigned()) {
return result;
}
switch (is_le) {
case l_true:
result = m_sort.le(k.get_unsigned(), coeffs.size(), coeffs.c_ptr(), m_args.c_ptr());
break;
case l_false:
result = m_sort.ge(k.get_unsigned(), coeffs.size(), coeffs.c_ptr(), m_args.c_ptr());
break;
case l_undef:
result = m_sort.eq(k.get_unsigned(), coeffs.size(), coeffs.c_ptr(), m_args.c_ptr());
break;
}
return result;
}
/**
\brief Segment based encoding.
The PB terms are partitoned into segments, such that each segment contains arguments with the same cofficient.