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Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
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Leonardo de Moura 2012-10-02 11:35:25 -07:00
parent 3f9edad676
commit e9eab22e5c
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lib/smt_checker.cpp Normal file
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/*++
Copyright (c) 2006 Microsoft Corporation
Module Name:
smt_checker.cpp
Abstract:
<abstract>
Author:
Leonardo de Moura (leonardo) 2008-06-20.
Revision History:
--*/
#include"smt_context.h"
#include"smt_checker.h"
#include"ast_ll_pp.h"
namespace smt {
bool checker::all_args(app * a, bool is_true) {
unsigned num_args = a->get_num_args();
for (unsigned i = 0; i < num_args; i++) {
if (!check(a->get_arg(i), is_true))
return false;
}
return true;
}
bool checker::any_arg(app * a, bool is_true) {
unsigned num_args = a->get_num_args();
for (unsigned i = 0; i < num_args; i++) {
if (check(a->get_arg(i), is_true))
return true;
}
return false;
}
bool checker::check_core(expr * n, bool is_true) {
SASSERT(m_manager.is_bool(n));
if (m_context.b_internalized(n) && m_context.is_relevant(n)) {
lbool val = m_context.get_assignment(n);
return val != l_undef && is_true == (val == l_true);
}
if (!is_app(n))
return false;
app * a = to_app(n);
if (a->get_family_id() == m_manager.get_basic_family_id()) {
switch (a->get_decl_kind()) {
case OP_TRUE:
return is_true;
case OP_FALSE:
return !is_true;
case OP_NOT:
return check(a->get_arg(0), !is_true);
case OP_OR:
return is_true ? any_arg(a, true) : all_args(a, false);
case OP_AND:
return is_true ? all_args(a, true) : any_arg(a, false);
case OP_IFF:
if (is_true) {
return
(check(a->get_arg(0), true) &&
check(a->get_arg(1), true)) ||
(check(a->get_arg(0), false) &&
check(a->get_arg(1), false));
}
else {
return
(check(a->get_arg(0), true) &&
check(a->get_arg(1), false)) ||
(check(a->get_arg(0), false) &&
check(a->get_arg(1), true));
}
case OP_ITE: {
if (m_context.lit_internalized(a->get_arg(0)) && m_context.is_relevant(a->get_arg(0))) {
switch (m_context.get_assignment(a->get_arg(0))) {
case l_false: return check(a->get_arg(2), is_true);
case l_undef: return false;
case l_true: return check(a->get_arg(1), is_true);
}
}
return check(a->get_arg(1), is_true) && check(a->get_arg(2), is_true);
}
case OP_EQ: {
enode * lhs = get_enode_eq_to(a->get_arg(0));
enode * rhs = get_enode_eq_to(a->get_arg(1));
if (lhs && rhs && m_context.is_relevant(lhs) && m_context.is_relevant(rhs)) {
if (is_true && lhs->get_root() == rhs->get_root())
return true;
// if (!is_true && m_context.is_ext_diseq(lhs, rhs, 2))
if (!is_true && m_context.is_diseq(lhs, rhs))
return true;
}
return false;
}
default:
break;
}
}
enode * e = get_enode_eq_to(a);
if (e && e->is_bool() && m_context.is_relevant(e)) {
lbool val = m_context.get_assignment(e->get_owner());
return val != l_undef && is_true == (val == l_true);
}
return false;
}
bool checker::check(expr * n, bool is_true) {
bool r;
if (n->get_ref_count() > 1 && m_is_true_cache[is_true].find(n, r))
return r;
r = check_core(n, is_true);
if (n->get_ref_count() > 1)
m_is_true_cache[is_true].insert(n, r);
return r;
}
enode * checker::get_enode_eq_to_core(app * n) {
ptr_buffer<enode> buffer;
unsigned num = n->get_num_args();
for (unsigned i = 0; i < num; i++) {
enode * arg = get_enode_eq_to(n->get_arg(i));
if (arg == 0)
return 0;
buffer.push_back(arg);
}
enode * e = m_context.get_enode_eq_to(n->get_decl(), num, buffer.c_ptr());
if (e == 0)
return 0;
return m_context.is_relevant(e) ? e : 0;
}
enode * checker::get_enode_eq_to(expr * n) {
if (is_var(n)) {
unsigned idx = to_var(n)->get_idx();
if (idx >= m_num_bindings)
return 0;
return m_bindings[m_num_bindings - idx - 1];
}
if (m_context.e_internalized(n) && m_context.is_relevant(n))
return m_context.get_enode(n);
if (!is_app(n) || to_app(n)->get_num_args() == 0)
return 0;
enode * r = 0;
if (n->get_ref_count() > 1 && m_to_enode_cache.find(n, r))
return r;
r = get_enode_eq_to_core(to_app(n));
if (n->get_ref_count() > 1)
m_to_enode_cache.insert(n, r);
return r;
}
bool checker::is_sat(expr * n, unsigned num_bindings, enode * const * bindings) {
flet<unsigned> l1(m_num_bindings, num_bindings);
flet<enode * const *> l2(m_bindings, bindings);
bool r = check(n, true);
m_is_true_cache[0].reset();
m_is_true_cache[1].reset();
m_to_enode_cache.reset();
return r;
}
bool checker::is_unsat(expr * n, unsigned num_bindings, enode * const * bindings) {
flet<unsigned> l1(m_num_bindings, num_bindings);
flet<enode * const *> l2(m_bindings, bindings);
bool r = check(n, false);
m_is_true_cache[0].reset();
m_is_true_cache[1].reset();
m_to_enode_cache.reset();
return r;
}
checker::checker(context & c):
m_context(c),
m_manager(c.get_manager()),
m_num_bindings(0),
m_bindings(0) {
}
};