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z3/lib/bv_elim.cpp
Leonardo de Moura e9eab22e5c Z3 sources
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2012-10-02 11:35:25 -07:00

114 lines
3.7 KiB
C++

#include "bv_elim.h"
#include "bv_decl_plugin.h"
#include "var_subst.h"
#include <sstream>
void bv_elim::elim(quantifier* q, quantifier_ref& r) {
svector<symbol> names, _names;
sort_ref_buffer sorts(m_manager), _sorts(m_manager);
expr_ref_buffer pats(m_manager);
expr_ref_buffer no_pats(m_manager);
expr_ref_buffer subst_map(m_manager), _subst_map(m_manager);
var_subst subst(m_manager);
bv_util bv(m_manager);
expr_ref new_body(m_manager);
expr* old_body = q->get_expr();
unsigned num_decls = q->get_num_decls();
family_id bfid = m_manager.get_family_id("bv");
//
// Traverse sequence of bound variables to eliminate
// bit-vecctor variables and replace them by
// Booleans.
//
unsigned var_idx = 0;
for (unsigned i = num_decls; i > 0; ) {
--i;
sort* s = q->get_decl_sort(i);
symbol nm = q->get_decl_name(i);
if (bv.is_bv_sort(s)) {
// convert n-bit bit-vector variable into sequence of n-Booleans.
unsigned num_bits = bv.get_bv_size(s);
expr_ref_buffer args(m_manager);
expr_ref bv(m_manager);
for (unsigned j = 0; j < num_bits; ++j) {
std::ostringstream new_name;
new_name << nm.str();
new_name << "_";
new_name << j;
var* v = m_manager.mk_var(var_idx++, m_manager.mk_bool_sort());
args.push_back(v);
_sorts.push_back(m_manager.mk_bool_sort());
_names.push_back(symbol(new_name.str().c_str()));
}
bv = m_manager.mk_app(bfid, OP_MKBV, 0, 0, args.size(), args.c_ptr());
_subst_map.push_back(bv.get());
}
else {
_subst_map.push_back(m_manager.mk_var(var_idx++, s));
_sorts.push_back(s);
_names.push_back(nm);
}
}
//
// reverse the vectors.
//
SASSERT(_names.size() == _sorts.size());
for (unsigned i = _names.size(); i > 0; ) {
--i;
names.push_back(_names[i]);
sorts.push_back(_sorts[i]);
}
for (unsigned i = _subst_map.size(); i > 0; ) {
--i;
subst_map.push_back(_subst_map[i]);
}
expr* const* sub = subst_map.c_ptr();
unsigned sub_size = subst_map.size();
subst(old_body, sub_size, sub, new_body);
for (unsigned j = 0; j < q->get_num_patterns(); j++) {
expr_ref pat(m_manager);
subst(q->get_pattern(j), sub_size, sub, pat);
pats.push_back(pat);
}
for (unsigned j = 0; j < q->get_num_no_patterns(); j++) {
expr_ref nopat(m_manager);
subst(q->get_no_pattern(j), sub_size, sub, nopat);
no_pats.push_back(nopat);
}
r = m_manager.mk_quantifier(true,
names.size(),
sorts.c_ptr(),
names.c_ptr(),
new_body.get(),
q->get_weight(),
q->get_qid(),
q->get_skid(),
pats.size(), pats.c_ptr(),
no_pats.size(), no_pats.c_ptr());
}
bool bv_elim_star::visit_quantifier(quantifier* q) {
// behave like destructive resolution, do not recurse.
return true;
}
void bv_elim_star::reduce1_quantifier(quantifier* q) {
quantifier_ref r(m_manager);
proof_ref pr(m_manager);
m_bv_elim.elim(q, r);
if (m_manager.fine_grain_proofs()) {
pr = m_manager.mk_rewrite(q, r.get());
}
else {
pr = 0;
}
cache_result(q, r, pr);
}