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add recursive function graphs to model, adapt rewriter to bypass branches whose evaluation is redundant

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-02-16 13:58:12 -08:00
parent c67cf1653c
commit b0dd3f3238
4 changed files with 63 additions and 0 deletions
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45
src/smt/smt_context.cpp
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@ -4123,6 +4123,7 @@ namespace smt {
if (fcs == FC_DONE) {
mk_proto_model(l_true);
m_model = m_proto_model->mk_model();
add_rec_funs_to_model();
}
return fcs == FC_DONE;
@ -4175,8 +4176,52 @@ namespace smt {
return m_last_search_failure;
}
void context::add_rec_funs_to_model() {
ast_manager& m = m_manager;
SASSERT(m_model);
for (unsigned i = 0; i < m_asserted_formulas.get_num_formulas(); ++i) {
expr* e = m_asserted_formulas.get_formula(i);
if (is_quantifier(e)) {
quantifier* q = to_quantifier(e);
std::cout << mk_pp(q, m) << "\n";
if (!m.is_rec_fun_def(q)) continue;
SASSERT(q->get_num_patterns() == 1);
expr* fn = to_app(q->get_pattern(0))->get_arg(0);
SASSERT(is_app(fn));
func_decl* f = to_app(fn)->get_decl();
expr* eq = q->get_expr();
expr_ref body(m);
if (is_fun_def(fn, q->get_expr(), body)) {
func_interp* fi = alloc(func_interp, m, f->get_arity());
fi->set_else(body);
m_model->register_decl(f, fi);
}
}
}
}
bool context::is_fun_def(expr* f, expr* body, expr_ref& result) {
expr* t1, *t2, *t3;
if (m_manager.is_eq(body, t1, t2) || m_manager.is_iff(body, t1, t2)) {
if (t1 == f) return result = t2, true;
if (t2 == f) return result = t1, true;
return false;
}
if (m_manager.is_ite(body, t1, t2, t3)) {
expr_ref body1(m_manager), body2(m_manager);
if (is_fun_def(f, t2, body1) && is_fun_def(f, t3, body2)) {
// f is not free in t1
result = m_manager.mk_ite(t1, body1, body2);
return true;
}
}
return false;
}
};
#ifdef Z3DEBUG
void pp(smt::context & c) {
c.display(std::cout);