void subsitute_invariants_rec(
const invariant_sett::invariantst &invariants,
exprt &dest)
{
if((dest.id()==ID_and ||
dest.id()==ID_or ||
dest.id()==ID_not) &&
dest.type().id()==ID_bool)
{
Forall_operands(it, dest)
subsitute_invariants_rec(invariants, *it);
}
else
{
#if 0
for(invariant_sett::invariantst::expr_sett::const_iterator
it=invariants.expr_set().begin();
it!=invariants.expr_set().end();
it++)
std::cout << "I: " << it->pretty() << std::endl;
std::cout << "DEST: " << dest.pretty() << std::endl;
#endif
if(invariants.expr_set().find(dest)!=
invariants.expr_set().end())
{
dest.make_true();
}
else
{
// inverted?
exprt tmp(dest);
tmp.make_not();
if(invariants.expr_set().find(tmp)!=
invariants.expr_set().end())
{
dest.make_false();
}
}
}
}
void gen_binary(exprt &expr, const std::string &id, bool default_value)
{
if(expr.operands().size()==0)
{
if(default_value)
expr.make_true();
else
expr.make_false();
}
else if(expr.operands().size()==1)
{
exprt tmp;
tmp.swap(expr.op0());
expr.swap(tmp);
}
else
{
expr.id(id);
expr.type()=typet("bool");
}
}
void make_it_a_predicate(
const predicatest &predicates,
exprt &expr,
const namespacet &ns)
{
bool negation;
canonicalize(expr, negation, ns);
// see if we have it
unsigned nr;
if(predicates.find(expr, nr))
{
// yes, we do!
// see if it is a constant
if(predicates[nr].is_true())
expr.make_true();
else if(predicates[nr].is_false())
expr.make_false();
else
{
expr=exprt(ID_predicate_symbol, typet(ID_bool));
expr.set(ID_identifier, nr);
}
if(negation)
expr.make_not();
}
else
{
// nah, we don't
// make it nondeterministic choice
exprt tmp(ID_nondet_symbol, typet(ID_bool));
tmp.add(ID_expression).swap(expr);
expr.swap(tmp);
}
}
bool c_typecheck_baset::zero_initializer(exprt &value, const typet &type) const
{
const std::string &type_id = type.id_string();
if(type_id == "bool")
{
value.make_false();
return false;
}
if(
type_id == "unsignedbv" || type_id == "signedbv" || type_id == "floatbv" ||
type_id == "fixedbv" || type_id == "pointer")
{
value = gen_zero(type);
return false;
}
else if(type_id == "code")
return false;
else if(type_id == "c_enum" || type_id == "incomplete_c_enum")
{
value = exprt("constant", type);
value.value(i2string(0));
return false;
}
else if(type_id == "array")
{
const array_typet &array_type = to_array_type(type);
exprt tmpval;
if(zero_initializer(tmpval, array_type.subtype()))
return true;
const exprt &size_expr = array_type.size();
if(size_expr.id() == "infinity")
{
}
else
{
mp_integer size;
if(to_integer(size_expr, size))
return true;
// Permit GCC zero sized arrays; disallow negative sized arrays.
// Cringe slightly when doing it though.
if(size < 0)
return true;
}
value = exprt("array_of", type);
value.move_to_operands(tmpval);
return false;
}
else if(type_id == "struct")
{
const irept::subt &components = type.components().get_sub();
value = exprt("struct", type);
forall_irep(it, components)
{
exprt tmp;
if(zero_initializer(tmp, (const typet &)it->type()))
return true;
value.move_to_operands(tmp);
}
return false;
}
void abstract_expression(
const predicatest &predicates,
exprt &expr,
const namespacet &ns)
{
if(expr.type().id()!=ID_bool)
throw "abstract_expression expects expression of type Boolean";
simplify(expr, ns);
if(is_valid(expr, ns))
{
// If expr is valid, we can abstract it as 'true'
expr.make_true();
} else if(is_unsatisfiable(expr, ns))
{
// If expr is unsatisfiable, we can abstract it as 'false'
expr.make_false();
} else if(expr.id()==ID_and || expr.id()==ID_or ||
expr.id()==ID_implies || expr.id()==ID_xor)
{
Forall_operands(it, expr)
abstract_expression(predicates, *it, ns);
}
else if(expr.id()==ID_not)
{
assert(expr.operands().size()==1);
abstract_expression(predicates, expr.op0(), ns);
// remove double negation
if(expr.op0().id()==ID_not &&
expr.op0().operands().size()==1)
{
exprt tmp;
tmp.swap(expr.op0().op0());
expr.swap(tmp);
}
}
else if(expr.id()==ID_if)
{
assert(expr.operands().size()==3);
Forall_operands(it, expr)
abstract_expression(predicates, *it, ns);
exprt true_expr(ID_and, bool_typet());
true_expr.copy_to_operands(expr.op0(), expr.op1());
exprt false_expr(ID_and, bool_typet());
false_expr.copy_to_operands(gen_not(expr.op0()), expr.op2());
exprt or_expr(ID_or, bool_typet());
or_expr.move_to_operands(true_expr, false_expr);
expr.swap(or_expr);
}
else if(expr.id()==ID_equal || expr.id()==ID_notequal)
{
if(expr.operands().size()!=2)
throw expr.id_string()+" takes two operands";
// Is it equality on Booleans?
if(expr.op0().type().id()==ID_bool &&
expr.op1().type().id()==ID_bool)
{
// leave it in
Forall_operands(it, expr)
abstract_expression(predicates, *it, ns);
}
else // other types, make it a predicate
{
if(has_non_boolean_if(expr))
{
lift_if(expr);
abstract_expression(predicates, expr, ns);
}
else
make_it_a_predicate(predicates, expr, ns);
}
}
else if(expr.is_constant())
{
// leave it as is
}
else if(has_non_boolean_if(expr))
{
lift_if(expr);
abstract_expression(predicates, expr, ns);
}
else
{
make_it_a_predicate(predicates, expr, ns);
}
}
