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https://github.com/Z3Prover/z3
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More work on trailing 0 analysis.
This commit is contained in:
mikolas
Mikolas Janota
parent
c7f1746321
commit
78cb1e3c7b
6 changed files with 181 additions and 68 deletions
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@ -22,19 +22,22 @@
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struct bv_trailing::imp {
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typedef rational numeral;
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bv_util m_util;
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typedef obj_map<expr, std::pair<unsigned,unsigned> > map;
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mk_extract_proc& m_mk_extract;
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bv_util& m_util;
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ast_manager& m_m;
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mk_extract_proc& m_mk_extract;
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imp(ast_manager& m, mk_extract_proc& mk_extract)
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: m_m(m)
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, m_util(m)
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, m_mk_extract(mk_extract)
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map m_count_cache;
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imp(mk_extract_proc& mk_extract)
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: m_mk_extract(mk_extract)
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, m_util(mk_extract.bvutil())
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, m_m(mk_extract.m())
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{ }
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virtual ~imp() { }
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ast_manager & m() const { return m_util.get_manager(); }
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void reset_cache() { m_count_cache.reset(); }
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br_status eq_remove_trailing(expr * e1, expr * e2, expr_ref& result) {
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TRACE("bv-trailing", tout << mk_ismt2_pp(e1, m()) << "\n=\n" << mk_ismt2_pp(e2, m()) << "\n";);
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@ -65,14 +68,47 @@ struct bv_trailing::imp {
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return BR_REWRITE2;
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}
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unsigned remove_trailing_mul(app * a, unsigned n, expr_ref& result, unsigned depth) {
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SASSERT(m_util.is_bv_mul(a));
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unsigned remove_trailing_add(app * a, unsigned n, expr_ref& result, unsigned depth) {
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SASSERT(m_util.is_bv_add(a));
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const unsigned num = a->get_num_args();
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if (depth <= 1) {
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result = a;
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return 0;
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}
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unsigned min, max;
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count_trailing(a, min, max, depth);
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const unsigned to_rm = std::min(min, n);
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if (to_rm == 0) {
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result = a;
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return 0;
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}
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const unsigned sz = m_util.get_bv_size(a);
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if (to_rm == sz) {
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result = NULL;
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return sz;
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}
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expr_ref_vector new_args(m());
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expr_ref tmp(m());
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for (unsigned i = 0; i < num; ++i) {
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expr * const curr = a->get_arg(i);
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const unsigned crm = remove_trailing(curr, to_rm, tmp, depth - 1);
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new_args.push_back(tmp);
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SASSERT(crm == to_rm);
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}
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result = m().mk_app(m_util.get_fid(), OP_BADD, new_args.size(), new_args.c_ptr());
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return to_rm;
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}
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unsigned remove_trailing_mul(app * a, unsigned n, expr_ref& result, unsigned depth) {
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SASSERT(m_util.is_bv_mul(a));
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const unsigned num = a->get_num_args();
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if (!num) return 0;
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if (depth <= 1 || !num) {
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result = a;
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return 0;
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}
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expr_ref tmp(m());
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expr * const coefficient = a->get_arg(0);
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const unsigned retv = remove_trailing(coefficient, n, tmp, depth - 1);
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@ -114,7 +150,7 @@ struct bv_trailing::imp {
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return 0;
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}
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unsigned num = a->get_num_args();
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unsigned retv = 0;
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unsigned retv = 0;
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unsigned i = num;
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expr_ref new_last(NULL, m());
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while (i && retv < n) {
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@ -130,8 +166,9 @@ struct bv_trailing::imp {
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return 0;
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}
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if (!i) {
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if (!i) {// all args eaten completely
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SASSERT(new_last.get() == NULL);
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SASSERT(retv == m_util.get_bv_size(a));
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result = NULL;
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return retv;
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}
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@ -140,7 +177,8 @@ struct bv_trailing::imp {
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for (size_t j=0; j<i;++j)
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new_args.push_back(a->get_arg(j));
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if (new_last.get()) new_args.push_back(new_last);
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result = m_util.mk_concat(new_args.size(), new_args.c_ptr());
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result = new_args.size() == 1 ? new_args.get(0)
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: m_util.mk_concat(new_args.size(), new_args.c_ptr());
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return retv;
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}
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@ -157,8 +195,8 @@ struct bv_trailing::imp {
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unsigned remove_trailing(expr * e, unsigned n, expr_ref& result, unsigned depth) {
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const unsigned retv = remove_trailing_core(e, n, result, depth);
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TRACE("bv-trailing", tout << mk_ismt2_pp(e, m()) << "\n" <<
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"--->" << mk_ismt2_pp(result.get(), m()) << "\n";);
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CTRACE("bv-trailing", result.get(), tout << mk_ismt2_pp(e, m()) << "\n--->\n" << mk_ismt2_pp(result.get(), m()) << "\n";);
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CTRACE("bv-trailing", !result.get(), tout << mk_ismt2_pp(e, m()) << "\n---> [EMPTY]\n";);
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return retv;
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}
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@ -177,17 +215,29 @@ struct bv_trailing::imp {
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}
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if (m_util.is_bv_mul(e))
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return remove_trailing_mul(to_app(e), n, result, depth);
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if (m_util.is_bv_add(e))
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return remove_trailing_add(to_app(e), n, result, depth);
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if (m_util.is_concat(e))
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return remove_trailing_concat(to_app(e), n, result, depth);
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return 0;
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}
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void count_trailing(expr * e, unsigned& min, unsigned& max, unsigned depth) {
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std::pair<unsigned, unsigned> cached;
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if (m_count_cache.find(e, cached)) { // check cache first
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min = cached.first;
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max = cached.second;
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return;
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}
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SASSERT(e && m_util.is_bv(e));
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count_trailing_core(e, min, max, depth);
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TRACE("bv-trailing", tout << mk_ismt2_pp(e, m()) << "\n:" << min << " - " << max << "\n";);
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SASSERT(min <= max);
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SASSERT(max <= m_util.get_bv_size(e));
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// store into the cache
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cached.first = min;
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cached.second = max;
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m_count_cache.insert(e, cached);
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}
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void count_trailing_concat(app * a, unsigned& min, unsigned& max, unsigned depth) {
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@ -213,6 +263,29 @@ struct bv_trailing::imp {
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}
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}
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void count_trailing_add(app * a, unsigned& min, unsigned& max, unsigned depth) {
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if (depth <= 1) {
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min = 0;
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max = m_util.get_bv_size(a);
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}
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const unsigned num = a->get_num_args();
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const unsigned sz = m_util.get_bv_size(a);
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min = max = sz; // treat empty addition as 0
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unsigned tmp_min;
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unsigned tmp_max;
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bool known_parity = true;
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bool is_odd = false;
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for (unsigned i = 0; i < num; ++i) {
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expr * const curr = a->get_arg(i);
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count_trailing(curr, tmp_min, tmp_max, depth - 1);
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min = std::min(min, tmp_min);
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known_parity = known_parity && (!tmp_max || tmp_min);
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if (known_parity && !tmp_max) is_odd = !is_odd;
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if (!known_parity && !min) break; // no more information can be gained
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}
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max = known_parity && is_odd ? 0 : sz; // max is known if parity is 1
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}
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void count_trailing_mul(app * a, unsigned& min, unsigned& max, unsigned depth) {
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if (depth <= 1) {
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min = 0;
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@ -251,6 +324,7 @@ struct bv_trailing::imp {
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return;
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}
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if (m_util.is_bv_mul(e)) count_trailing_mul(to_app(e), min, max, depth);
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else if (m_util.is_bv_add(e)) count_trailing_add(to_app(e), min, max, depth);
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else if (m_util.is_concat(e)) count_trailing_concat(to_app(e), min, max, depth);
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else {
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min = 0;
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@ -259,18 +333,14 @@ struct bv_trailing::imp {
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}
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};
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bv_trailing::bv_trailing(ast_manager& m, mk_extract_proc& mk_extract) {
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m_imp = alloc(imp, m, mk_extract);
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bv_trailing::bv_trailing(mk_extract_proc& mk_extract) {
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m_imp = alloc(imp, mk_extract);
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}
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bv_trailing::~bv_trailing() {
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if (m_imp) dealloc(m_imp);
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}
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void bv_trailing::count_trailing(expr * e, unsigned& min, unsigned& max, unsigned depth) {
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m_imp->count_trailing(e, min, max, depth);
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}
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br_status bv_trailing::eq_remove_trailing(expr * e1, expr * e2, expr_ref& result) {
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return m_imp->eq_remove_trailing(e1, e2, result);
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}
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@ -279,4 +349,6 @@ unsigned bv_trailing::remove_trailing(expr * e, unsigned n, expr_ref& result, un
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return m_imp->remove_trailing(e, n, result, depth);
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}
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void bv_trailing::reset_cache() {
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m_imp->reset_cache();
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}
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