void guardt::add(const exprt &expr)
{
assert(expr.type().id()==ID_bool);
if(is_false() || expr.is_true())
return;
else if(is_true() || expr.is_false())
{
*this=expr;
return;
}
else if(id()!=ID_and)
{
and_exprt a;
a.copy_to_operands(*this);
*this=a;
}
operandst &op=operands();
if(expr.id()==ID_and)
op.insert(op.end(),
expr.operands().begin(),
expr.operands().end());
else
op.push_back(expr);
}
/// checks whether a termination argument implies termination
threevalt summarizer_fw_termt::check_termination_argument(exprt expr)
{
if(expr.is_false())
return YES;
// should be of the form /\_i g_i=> R_i
if(expr.id()==ID_and)
{
threevalt result=YES;
for(exprt::operandst::iterator it=expr.operands().begin();
it!=expr.operands().end(); it++)
{
if(it->is_true())
result=UNKNOWN;
if(it->id()==ID_implies)
{
if(it->op1().is_true())
result=UNKNOWN;
}
}
return result;
}
else
{
if(expr.id()==ID_implies)
{
if(expr.op1().is_true())
return UNKNOWN;
}
else
return !expr.is_true() ? YES : UNKNOWN;
}
return YES;
}
void invariant_sett::strengthen_rec(const exprt &expr)
{
if(expr.type().id()!=ID_bool)
throw "non-Boolean argument to strengthen()";
#if 0
std::cout << "S: " << from_expr(*ns, "", expr) << '\n';
#endif
if(is_false)
{
// we can't get any stronger
return;
}
if(expr.is_true())
{
// do nothing, it's useless
}
else if(expr.is_false())
{
// wow, that's strong
make_false();
}
else if(expr.id()==ID_not)
{
// give up, we expect NNF
}
else if(expr.id()==ID_and)
{
forall_operands(it, expr)
strengthen_rec(*it);
}
else if(expr.id()==ID_le ||
expr.id()==ID_lt)
{
assert(expr.operands().size()==2);
// special rule: x <= (a & b)
// implies: x<=a && x<=b
if(expr.op1().id()==ID_bitand)
{
const exprt &bitand_op=expr.op1();
forall_operands(it, bitand_op)
{
exprt tmp(expr);
tmp.op1()=*it;
strengthen_rec(tmp);
}
return;
}
void cvc_convt::convert_as_bv(const exprt &expr)
{
if(expr.type().id()==ID_bool)
{
if(expr.is_true())
out << "0bin1";
else if(expr.is_false())
out << "0bin0";
else
{
out << "IF ";
convert_expr(expr);
out << " THEN 0bin1 ELSE 0bin0 ENDIF";
}
}
else
convert_expr(expr);
}
void precondition(
const namespacet &ns,
value_setst &value_sets,
const goto_programt::const_targett target,
const symex_target_equationt &equation,
const goto_symex_statet &s,
exprt &dest)
{
for(symex_target_equationt::SSA_stepst::const_reverse_iterator
it=equation.SSA_steps.rbegin();
it!=equation.SSA_steps.rend();
it++)
{
preconditiont precondition(ns, value_sets, target, *it, s);
precondition.compute(dest);
if(dest.is_false()) return;
}
}
void guardt::guard_expr(exprt &dest) const
{
if(is_true())
{
// do nothing
}
else
{
if(dest.is_false())
{
dest=as_expr();
dest.make_not();
}
else
{
implies_exprt tmp;
tmp.op0()=as_expr();
tmp.op1().swap(dest);
dest.swap(tmp);
}
}
}
literalt cvc_convt::convert(const exprt &expr)
{
//out << "%% E: " << expr << std::endl;
if(expr.type().id()!=ID_bool)
{
std::string msg="cvc_convt::convert got "
"non-boolean expression: ";
msg+=expr.pretty();
throw msg;
}
// Three special cases in which we don't need to generate
// a handle.
if(expr.is_true())
return const_literal(true);
else if(expr.is_false())
return const_literal(false);
else if(expr.id()==ID_literal)
return to_literal_expr(expr).get_literal();
// Generate new handle
literalt l(no_boolean_variables, false);
no_boolean_variables++;
find_symbols(expr);
// define new handle
out << "ASSERT ";
convert_literal(l);
out << " <=> (";
convert_expr(expr);
out << ");" << std::endl << std::endl;
return l;
}
void dplib_convt::convert_dplib_expr(const exprt &expr)
{
if(expr.id()==ID_symbol)
{
convert_identifier(expr.get_string(ID_identifier));
}
else if(expr.id()==ID_nondet_symbol)
{
convert_identifier("nondet$"+expr.get_string(ID_identifier));
}
else if(expr.id()==ID_typecast)
{
assert(expr.operands().size()==1);
const exprt &op=expr.op0();
if(expr.type().id()==ID_bool)
{
if(op.type().id()==ID_signedbv ||
op.type().id()==ID_unsignedbv ||
op.type().id()==ID_pointer)
{
convert_dplib_expr(op);
dplib_prop.out << "/=";
convert_dplib_expr(gen_zero(op.type()));
}
else
{
throw "TODO typecast1 "+op.type().id_string()+" -> bool";
}
}
else if(expr.type().id()==ID_signedbv ||
expr.type().id()==ID_unsignedbv)
{
unsigned to_width=unsafe_string2unsigned(id2string(expr.type().get(ID_width)));
if(op.type().id()==ID_signedbv)
{
unsigned from_width=unsafe_string2unsigned(id2string(op.type().get(ID_width)));
if(from_width==to_width)
convert_dplib_expr(op);
else if(from_width<to_width)
{
dplib_prop.out << "SX(";
convert_dplib_expr(op);
dplib_prop.out << ", " << to_width << ")";
}
else
{
dplib_prop.out << "(";
convert_dplib_expr(op);
dplib_prop.out << ")[" << (to_width-1) << ":0]";
}
}
else if(op.type().id()==ID_unsignedbv)
{
unsigned from_width=unsafe_string2unsigned(id2string(op.type().get(ID_width)));
if(from_width==to_width)
convert_dplib_expr(op);
else if(from_width<to_width)
{
dplib_prop.out << "(0bin";
for(unsigned i=from_width; i<to_width; i++)
dplib_prop.out << "0";
dplib_prop.out << " @ ";
dplib_prop.out << "(";
convert_dplib_expr(op);
dplib_prop.out << "))";
}
else
{
dplib_prop.out << "(";
convert_dplib_expr(op);
dplib_prop.out << ")[" << (to_width-1) << ":0]";
}
}
else if(op.type().id()==ID_bool)
{
if(to_width>1)
{
dplib_prop.out << "(0bin";
for(unsigned i=1; i<to_width; i++)
dplib_prop.out << "0";
dplib_prop.out << " @ ";
dplib_prop.out << "IF ";
convert_dplib_expr(op);
dplib_prop.out << " THEN 0bin1 ELSE 0bin0 ENDIF)";
}
else
{
dplib_prop.out << "IF ";
convert_dplib_expr(op);
dplib_prop.out << " THEN 0bin1 ELSE 0bin0 ENDIF";
}
}
else
{
throw "TODO typecast2 "+op.type().id_string()+
" -> "+expr.type().id_string();
}
}
else if(expr.type().id()==ID_pointer)
{
if(op.type().id()==ID_pointer)
{
convert_dplib_expr(op);
}
else
throw "TODO typecast3 "+op.type().id_string()+" -> pointer";
}
else
throw "TODO typecast4 ? -> "+expr.type().id_string();
}
else if(expr.id()==ID_struct)
{
dplib_prop.out << "(# ";
const struct_typet &struct_type=to_struct_type(expr.type());
const struct_typet::componentst &components=
struct_type.components();
assert(components.size()==expr.operands().size());
unsigned i=0;
for(struct_typet::componentst::const_iterator
it=components.begin();
it!=components.end();
it++, i++)
{
if(i!=0) dplib_prop.out << ", ";
dplib_prop.out << it->get(ID_name);
dplib_prop.out << ":=";
convert_dplib_expr(expr.operands()[i]);
}
dplib_prop.out << " #)";
}
else if(expr.id()==ID_constant)
{
if(expr.type().id()==ID_unsignedbv ||
expr.type().id()==ID_signedbv ||
expr.type().id()==ID_bv)
{
dplib_prop.out << "0bin" << expr.get(ID_value);
}
else if(expr.type().id()==ID_pointer)
{
const irep_idt &value=expr.get(ID_value);
if(value=="NULL")
{
dplib_prop.out << "(# object:="
<< pointer_logic.get_null_object()
<< ", offset:="
<< bin_zero(config.ansi_c.pointer_width) << " #)";
}
else
throw "unknown pointer constant: "+id2string(value);
}
else if(expr.type().id()==ID_bool)
{
if(expr.is_true())
dplib_prop.out << "TRUE";
else if(expr.is_false())
dplib_prop.out << "FALSE";
else
throw "unknown boolean constant";
}
else if(expr.type().id()==ID_array)
{
dplib_prop.out << "ARRAY (i: " << array_index_type() << "):";
assert(!expr.operands().empty());
unsigned i=0;
forall_operands(it, expr)
{
if(i==0)
dplib_prop.out << "\n IF ";
else
dplib_prop.out << "\n ELSIF ";
dplib_prop.out << "i=" << array_index(i) << " THEN ";
convert_array_value(*it);
i++;
}
dplib_prop.out << "\n ELSE ";
convert_dplib_expr(expr.op0());
dplib_prop.out << "\n ENDIF";
}
else if(expr.type().id()==ID_integer ||
bool prop_convt::get_bool(const exprt &expr, tvt &value) const
{
// trivial cases
if(expr.is_true())
{
value=tvt(true);
return false;
}
else if(expr.is_false())
{
value=tvt(false);
return false;
}
else if(expr.id()==ID_symbol)
{
symbolst::const_iterator result=
symbols.find(to_symbol_expr(expr).get_identifier());
if(result==symbols.end()) return true;
value=prop.l_get(result->second);
return false;
}
// sub-expressions
if(expr.id()==ID_not)
{
if(expr.type().id()==ID_bool &&
expr.operands().size()==1)
{
if(get_bool(expr.op0(), value)) return true;
value=!value;
return false;
}
}
else if(expr.id()==ID_and || expr.id()==ID_or)
{
if(expr.type().id()==ID_bool &&
expr.operands().size()>=1)
{
value=tvt(expr.id()==ID_and);
forall_operands(it, expr)
{
tvt tmp;
if(get_bool(*it, tmp)) return true;
if(expr.id()==ID_and)
{
if(tmp.is_false()) { value=tvt(false); return false; }
value=value && tmp;
}
else // or
{
if(tmp.is_true()) { value=tvt(true); return false; }
value=value || tmp;
}
}
return false;
}