bvt boolbvt::convert_with(const exprt &expr)
{
if(expr.operands().size()<3)
{
error().source_location=expr.find_source_location();
error() << "with takes at least three operands" << eom;
throw 0;
}
if((expr.operands().size()%2)!=1)
{
error().source_location=expr.find_source_location();
error() << "with takes an odd number of operands" << eom;
throw 0;
}
bvt bv=convert_bv(expr.op0());
std::size_t width=boolbv_width(expr.type());
if(width==0)
return conversion_failed(expr);
if(bv.size()!=width)
{
error().source_location=expr.find_source_location();
error() << "unexpected operand 0 width" << eom;
throw 0;
}
bvt prev_bv;
prev_bv.resize(width);
const exprt::operandst &ops=expr.operands();
for(std::size_t op_no=1; op_no<ops.size(); op_no+=2)
{
bv.swap(prev_bv);
convert_with(expr.op0().type(),
ops[op_no],
ops[op_no+1],
prev_bv,
bv);
}
return bv;
}
void goto_checkt::pointer_overflow_check(
const exprt &expr,
const guardt &guard)
{
if(!enable_pointer_overflow_check)
return;
if(expr.id()==ID_plus ||
expr.id()==ID_minus)
{
if(expr.operands().size()==2)
{
exprt overflow("overflow-"+expr.id_string(), bool_typet());
overflow.operands()=expr.operands();
add_guarded_claim(
not_exprt(overflow),
"pointer arithmetic overflow on "+expr.id_string(),
"overflow",
expr.find_source_location(),
expr,
guard);
}
}
}
void goto_checkt::pointer_rel_check(
const exprt &expr,
const guardt &guard)
{
if(!enable_pointer_check)
return;
if(expr.operands().size()!=2)
throw expr.id_string()+" takes two arguments";
if(expr.op0().type().id()==ID_pointer &&
expr.op1().type().id()==ID_pointer)
{
// add same-object subgoal
if(enable_pointer_check)
{
exprt same_object=::same_object(expr.op0(), expr.op1());
add_guarded_claim(
same_object,
"same object violation",
"pointer",
expr.find_source_location(),
expr,
guard);
}
}
}
void goto_convertt::do_function_call(
const exprt &lhs,
const exprt &function,
const exprt::operandst &arguments,
goto_programt &dest)
{
// make it all side effect free
exprt new_lhs=lhs,
new_function=function;
exprt::operandst new_arguments=arguments;
if(!new_lhs.is_nil())
clean_expr(new_lhs, dest);
clean_expr(new_function, dest);
// the arguments of __noop do not get evaluated
if(new_function.id()==ID_symbol &&
to_symbol_expr(new_function).get_identifier()=="__noop")
{
new_arguments.clear();
}
Forall_expr(it, new_arguments)
clean_expr(*it, dest);
// split on the function
if(new_function.id()==ID_if)
{
do_function_call_if(new_lhs, to_if_expr(new_function), new_arguments, dest);
}
else if(new_function.id()==ID_symbol)
{
do_function_call_symbol(new_lhs, to_symbol_expr(new_function), new_arguments, dest);
}
else if(new_function.id()=="NULL-object")
{
}
else if(new_function.id()==ID_dereference ||
new_function.id()=="virtual_function")
{
do_function_call_other(new_lhs, new_function, new_arguments, dest);
}
else
{
error().source_location=function.find_source_location();
error() << "unexpected function argument: " << new_function.id()
<< eom;
throw 0;
}
}
void c_typecheck_baset::implicit_typecast(
exprt &expr,
const typet &dest_type)
{
c_typecastt c_typecast(*this);
typet src_type=expr.type();
c_typecast.implicit_typecast(expr, dest_type);
for(std::list<std::string>::const_iterator
it=c_typecast.errors.begin();
it!=c_typecast.errors.end();
it++)
{
error().source_location=expr.find_source_location();
error() << "in expression `" << to_string(expr) << "':\n"
<< "conversion from `"
<< to_string(src_type) << "' to `"
<< to_string(dest_type) << "': "
<< *it << eom;
}
if(!c_typecast.errors.empty())
throw 0; // give up
for(std::list<std::string>::const_iterator
it=c_typecast.warnings.begin();
it!=c_typecast.warnings.end();
it++)
{
warning().source_location=expr.find_source_location();
warning() << "warning: conversion from `"
<< to_string(src_type)
<< "' to `"
<< to_string(dest_type)
<< "': " << *it << eom;
}
}
exprt c_typecheck_baset::do_initializer_list(
const exprt &value,
const typet &type,
bool force_constant)
{
assert(value.id()==ID_initializer_list);
const typet &full_type=follow(type);
exprt result;
if(full_type.id()==ID_struct ||
full_type.id()==ID_union ||
full_type.id()==ID_vector)
{
// start with zero everywhere
result=
zero_initializer(
type, value.source_location(), *this, get_message_handler());
}
else if(full_type.id()==ID_array)
{
if(to_array_type(full_type).size().is_nil())
{
// start with empty array
result=exprt(ID_array, full_type);
result.add_source_location()=value.source_location();
}
else
{
// start with zero everywhere
result=
zero_initializer(
type, value.source_location(), *this, get_message_handler());
}
// 6.7.9, 14: An array of character type may be initialized by a character
// string literal or UTF-8 string literal, optionally enclosed in braces.
if(value.operands().size()>=1 &&
value.op0().id()==ID_string_constant &&
(full_type.subtype().id()==ID_signedbv ||
full_type.subtype().id()==ID_unsignedbv) &&
full_type.subtype().get(ID_width)==char_type().get(ID_width))
{
if(value.operands().size()>1)
{
warning().source_location=value.find_source_location();
warning() << "ignoring excess initializers" << eom;
}
return do_initializer_rec(value.op0(), type, force_constant);
}
}
else
{
// The initializer for a scalar shall be a single expression,
// * optionally enclosed in braces. *
if(value.operands().size()==1)
return do_initializer_rec(value.op0(), type, force_constant);
err_location(value);
error() << "cannot initialize `" << to_string(full_type)
<< "' with an initializer list" << eom;
throw 0;
}
designatort current_designator;
designator_enter(type, current_designator);
forall_operands(it, value)
{
do_designated_initializer(
result, current_designator, *it, force_constant);
// increase designator -- might go up
increment_designator(current_designator);
}
void goto_program_dereferencet::dereference_rec(
exprt &expr,
guardt &guard,
const value_set_dereferencet::modet mode)
{
if(!dereference.has_dereference(expr))
return;
if(expr.id()==ID_and || expr.id()==ID_or)
{
if(!expr.is_boolean())
throw expr.id_string()+" must be Boolean, but got "+
expr.pretty();
guardt old_guard=guard;
for(unsigned i=0; i<expr.operands().size(); i++)
{
exprt &op=expr.operands()[i];
if(!op.is_boolean())
throw expr.id_string()+" takes Boolean operands only, but got "+
op.pretty();
if(dereference.has_dereference(op))
dereference_rec(op, guard, value_set_dereferencet::modet::READ);
if(expr.id()==ID_or)
{
exprt tmp(op);
tmp.make_not();
guard.add(tmp);
}
else
guard.add(op);
}
guard.swap(old_guard);
return;
}
else if(expr.id()==ID_if)
{
if(expr.operands().size()!=3)
throw "if takes three arguments";
if(!expr.op0().is_boolean())
{
std::string msg=
"first argument of if must be boolean, but got "
+expr.op0().pretty();
throw msg;
}
dereference_rec(expr.op0(), guard, value_set_dereferencet::modet::READ);
bool o1=dereference.has_dereference(expr.op1());
bool o2=dereference.has_dereference(expr.op2());
if(o1)
{
guardt old_guard=guard;
guard.add(expr.op0());
dereference_rec(expr.op1(), guard, mode);
guard.swap(old_guard);
}
if(o2)
{
guardt old_guard=guard;
exprt tmp(expr.op0());
tmp.make_not();
guard.add(tmp);
dereference_rec(expr.op2(), guard, mode);
guard.swap(old_guard);
}
return;
}
if(expr.id()==ID_address_of ||
expr.id()=="reference_to")
{
// turn &*p to p
// this has *no* side effect!
assert(expr.operands().size()==1);
if(expr.op0().id()==ID_dereference)
{
assert(expr.op0().operands().size()==1);
exprt tmp;
tmp.swap(expr.op0().op0());
if(tmp.type()!=expr.type())
tmp.make_typecast(expr.type());
expr.swap(tmp);
}
}
Forall_operands(it, expr)
dereference_rec(*it, guard, mode);
if(expr.id()==ID_dereference)
{
if(expr.operands().size()!=1)
throw "dereference expects one operand";
dereference_location=expr.find_source_location();
exprt tmp=dereference.dereference(
expr.op0(), guard, mode);
expr.swap(tmp);
}
else if(expr.id()==ID_index)
{
// this is old stuff and will go away
if(expr.operands().size()!=2)
throw "index expects two operands";
if(expr.op0().type().id()==ID_pointer)
{
dereference_location=expr.find_source_location();
exprt tmp1(ID_plus, expr.op0().type());
tmp1.operands().swap(expr.operands());
exprt tmp2=dereference.dereference(tmp1, guard, mode);
tmp2.swap(expr);
}
}
}
void goto_checkt::nan_check(
const exprt &expr,
const guardt &guard)
{
if(!enable_nan_check)
return;
// first, check type
if(expr.type().id()!=ID_floatbv)
return;
if(expr.id()!=ID_plus &&
expr.id()!=ID_mult &&
expr.id()!=ID_div &&
expr.id()!=ID_minus)
return;
// add NaN subgoal
exprt isnan;
if(expr.id()==ID_div)
{
assert(expr.operands().size()==2);
// there a two ways to get a new NaN on division:
// 0/0 = NaN and x/inf = NaN
// (note that x/0 = +-inf for x!=0 and x!=inf)
exprt zero_div_zero=and_exprt(
ieee_float_equal_exprt(expr.op0(), gen_zero(expr.op0().type())),
ieee_float_equal_exprt(expr.op1(), gen_zero(expr.op1().type())));
exprt div_inf=unary_exprt(ID_isinf, expr.op1(), bool_typet());
isnan=or_exprt(zero_div_zero, div_inf);
}
else if(expr.id()==ID_mult)
{
if(expr.operands().size()>=3)
return nan_check(make_binary(expr), guard);
assert(expr.operands().size()==2);
// Inf * 0 is NaN
exprt inf_times_zero=and_exprt(
unary_exprt(ID_isinf, expr.op0(), bool_typet()),
ieee_float_equal_exprt(expr.op1(), gen_zero(expr.op1().type())));
exprt zero_times_inf=and_exprt(
ieee_float_equal_exprt(expr.op1(), gen_zero(expr.op1().type())),
unary_exprt(ID_isinf, expr.op0(), bool_typet()));
isnan=or_exprt(inf_times_zero, zero_times_inf);
}
else if(expr.id()==ID_plus)
{
if(expr.operands().size()>=3)
return nan_check(make_binary(expr), guard);
assert(expr.operands().size()==2);
// -inf + +inf = NaN and +inf + -inf = NaN,
// i.e., signs differ
ieee_float_spect spec=ieee_float_spect(to_floatbv_type(expr.type()));
exprt plus_inf=ieee_floatt::plus_infinity(spec).to_expr();
exprt minus_inf=ieee_floatt::minus_infinity(spec).to_expr();
isnan=or_exprt(
and_exprt(equal_exprt(expr.op0(), minus_inf), equal_exprt(expr.op1(), plus_inf)),
and_exprt(equal_exprt(expr.op0(), plus_inf), equal_exprt(expr.op1(), minus_inf)));
}
else if(expr.id()==ID_minus)
{
assert(expr.operands().size()==2);
// +inf - +inf = NaN and -inf - -inf = NaN,
// i.e., signs match
ieee_float_spect spec=ieee_float_spect(to_floatbv_type(expr.type()));
exprt plus_inf=ieee_floatt::plus_infinity(spec).to_expr();
exprt minus_inf=ieee_floatt::minus_infinity(spec).to_expr();
isnan=or_exprt(
and_exprt(equal_exprt(expr.op0(), plus_inf), equal_exprt(expr.op1(), plus_inf)),
and_exprt(equal_exprt(expr.op0(), minus_inf), equal_exprt(expr.op1(), minus_inf)));
}
else
assert(false);
isnan.make_not();
add_guarded_claim(
isnan,
"NaN on "+expr.id_string(),
"NaN",
expr.find_source_location(),
expr,
guard);
}
void goto_checkt::float_overflow_check(
const exprt &expr,
const guardt &guard)
{
if(!enable_float_overflow_check)
return;
// First, check type.
const typet &type=ns.follow(expr.type());
if(type.id()!=ID_floatbv)
return;
// add overflow subgoal
if(expr.id()==ID_typecast)
{
// Can overflow if casting from larger
// to smaller type.
assert(expr.operands().size()==1);
if(ns.follow(expr.op0().type()).id()==ID_floatbv)
{
// float-to-float
unary_exprt op0_inf(ID_isinf, expr.op0(), bool_typet());
unary_exprt new_inf(ID_isinf, expr, bool_typet());
or_exprt overflow_check(op0_inf, not_exprt(new_inf));
add_guarded_claim(
overflow_check,
"arithmetic overflow on floating-point typecast",
"overflow",
expr.find_source_location(),
expr,
guard);
}
else
{
// non-float-to-float
unary_exprt new_inf(ID_isinf, expr, bool_typet());
add_guarded_claim(
not_exprt(new_inf),
"arithmetic overflow on floating-point typecast",
"overflow",
expr.find_source_location(),
expr,
guard);
}
return;
}
else if(expr.id()==ID_div)
{
assert(expr.operands().size()==2);
// Can overflow if dividing by something small
unary_exprt new_inf(ID_isinf, expr, bool_typet());
unary_exprt op0_inf(ID_isinf, expr.op0(), bool_typet());
or_exprt overflow_check(op0_inf, not_exprt(new_inf));
add_guarded_claim(
overflow_check,
"arithmetic overflow on floating-point division",
"overflow",
expr.find_source_location(),
expr,
guard);
return;
}
else if(expr.id()==ID_mod)
{
// Can't overflow
return;
}
else if(expr.id()==ID_unary_minus)
{
// Can't overflow
return;
}
else if(expr.id()==ID_plus || expr.id()==ID_mult ||
expr.id()==ID_minus)
{
if(expr.operands().size()==2)
{
// Can overflow
unary_exprt new_inf(ID_isinf, expr, bool_typet());
unary_exprt op0_inf(ID_isinf, expr.op0(), bool_typet());
unary_exprt op1_inf(ID_isinf, expr.op1(), bool_typet());
or_exprt overflow_check(op0_inf, op1_inf, not_exprt(new_inf));
std::string kind=
expr.id()==ID_plus?"addition":
expr.id()==ID_minus?"subtraction":
expr.id()==ID_mult?"multiplication":"";
add_guarded_claim(
overflow_check,
"arithmetic overflow on floating-point "+kind,
"overflow",
expr.find_source_location(),
expr,
guard);
return;
}
else if(expr.operands().size()>=3)
{
assert(expr.id()!=ID_minus);
// break up
exprt tmp=make_binary(expr);
float_overflow_check(tmp, guard);
return;
}
}
}
void goto_checkt::integer_overflow_check(
const exprt &expr,
const guardt &guard)
{
if(!enable_signed_overflow_check &&
!enable_unsigned_overflow_check)
return;
// First, check type.
const typet &type=ns.follow(expr.type());
if(type.id()==ID_signedbv && !enable_signed_overflow_check)
return;
if(type.id()==ID_unsignedbv && !enable_unsigned_overflow_check)
return;
// add overflow subgoal
if(expr.id()==ID_div)
{
assert(expr.operands().size()==2);
// undefined for signed division INT_MIN/-1
if(type.id()==ID_signedbv)
{
equal_exprt int_min_eq(
expr.op0(), to_signedbv_type(type).smallest_expr());
equal_exprt minus_one_eq(
expr.op1(), from_integer(-1, type));
add_guarded_claim(
not_exprt(and_exprt(int_min_eq, minus_one_eq)),
"arithmetic overflow on signed division",
"overflow",
expr.find_source_location(),
expr,
guard);
}
return;
}
else if(expr.id()==ID_mod)
{
// these can't overflow
return;
}
else if(expr.id()==ID_unary_minus)
{
if(type.id()==ID_signedbv)
{
// overflow on unary- can only happen with the smallest
// representable number 100....0
equal_exprt int_min_eq(
expr.op0(), to_signedbv_type(type).smallest_expr());
add_guarded_claim(
not_exprt(int_min_eq),
"arithmetic overflow on signed unary minus",
"overflow",
expr.find_source_location(),
expr,
guard);
}
return;
}
exprt overflow("overflow-"+expr.id_string(), bool_typet());
overflow.operands()=expr.operands();
if(expr.operands().size()>=3)
{
// The overflow checks are binary!
// We break these up.
for(unsigned i=1; i<expr.operands().size(); i++)
{
exprt tmp;
if(i==1)
tmp=expr.op0();
else
{
tmp=expr;
tmp.operands().resize(i);
}
overflow.operands().resize(2);
overflow.op0()=tmp;
overflow.op1()=expr.operands()[i];
std::string kind=
type.id()==ID_unsignedbv?"unsigned":"signed";
add_guarded_claim(
not_exprt(overflow),
"arithmetic overflow on "+kind+" "+expr.id_string(),
"overflow",
expr.find_source_location(),
expr,
guard);
}
}
else
{
std::string kind=
type.id()==ID_unsignedbv?"unsigned":"signed";
add_guarded_claim(
not_exprt(overflow),
"arithmetic overflow on "+kind+" "+expr.id_string(),
"overflow",
expr.find_source_location(),
expr,
guard);
}
}
void goto_checkt::conversion_check(
const exprt &expr,
const guardt &guard)
{
if(!enable_conversion_check)
return;
// First, check type.
const typet &type=ns.follow(expr.type());
if(type.id()!=ID_signedbv &&
type.id()!=ID_unsignedbv)
return;
if(expr.id()==ID_typecast)
{
// conversion to signed int may overflow
if(expr.operands().size()!=1)
throw "typecast takes one operand";
const typet &old_type=ns.follow(expr.op0().type());
if(type.id()==ID_signedbv)
{
std::size_t new_width=to_signedbv_type(type).get_width();
if(old_type.id()==ID_signedbv) // signed -> signed
{
std::size_t old_width=to_signedbv_type(old_type).get_width();
if(new_width>=old_width) return; // always ok
binary_relation_exprt no_overflow_upper(ID_le);
no_overflow_upper.lhs()=expr.op0();
no_overflow_upper.rhs()=from_integer(power(2, new_width-1)-1, old_type);
binary_relation_exprt no_overflow_lower(ID_ge);
no_overflow_lower.lhs()=expr.op0();
no_overflow_lower.rhs()=from_integer(-power(2, new_width-1), old_type);
add_guarded_claim(
and_exprt(no_overflow_lower, no_overflow_upper),
"arithmetic overflow on signed type conversion",
"overflow",
expr.find_source_location(),
expr,
guard);
}
else if(old_type.id()==ID_unsignedbv) // unsigned -> signed
{
std::size_t old_width=to_unsignedbv_type(old_type).get_width();
if(new_width>=old_width+1) return; // always ok
binary_relation_exprt no_overflow_upper(ID_le);
no_overflow_upper.lhs()=expr.op0();
no_overflow_upper.rhs()=from_integer(power(2, new_width-1)-1, old_type);
add_guarded_claim(
no_overflow_upper,
"arithmetic overflow on unsigned to signed type conversion",
"overflow",
expr.find_source_location(),
expr,
guard);
}
else if(old_type.id()==ID_floatbv) // float -> signed
{
// Note that the fractional part is truncated!
ieee_floatt upper(to_floatbv_type(old_type));
upper.from_integer(power(2, new_width-1));
binary_relation_exprt no_overflow_upper(ID_lt);
no_overflow_upper.lhs()=expr.op0();
no_overflow_upper.rhs()=upper.to_expr();
ieee_floatt lower(to_floatbv_type(old_type));
lower.from_integer(-power(2, new_width-1)-1);
binary_relation_exprt no_overflow_lower(ID_gt);
no_overflow_lower.lhs()=expr.op0();
no_overflow_lower.rhs()=lower.to_expr();
add_guarded_claim(
and_exprt(no_overflow_lower, no_overflow_upper),
"arithmetic overflow on float to signed integer type conversion",
"overflow",
expr.find_source_location(),
expr,
guard);
}
}
else if(type.id()==ID_unsignedbv)
{
std::size_t new_width=to_unsignedbv_type(type).get_width();
if(old_type.id()==ID_signedbv) // signed -> unsigned
{
std::size_t old_width=to_signedbv_type(old_type).get_width();
if(new_width>=old_width-1)
{
// only need lower bound check
binary_relation_exprt no_overflow_lower(ID_ge);
no_overflow_lower.lhs()=expr.op0();
no_overflow_lower.rhs()=from_integer(0, old_type);
add_guarded_claim(
no_overflow_lower,
"arithmetic overflow on signed to unsigned type conversion",
"overflow",
expr.find_source_location(),
expr,
guard);
}
else
{
// need both
binary_relation_exprt no_overflow_upper(ID_le);
no_overflow_upper.lhs()=expr.op0();
no_overflow_upper.rhs()=from_integer(power(2, new_width)-1, old_type);
binary_relation_exprt no_overflow_lower(ID_ge);
no_overflow_lower.lhs()=expr.op0();
no_overflow_lower.rhs()=from_integer(0, old_type);
add_guarded_claim(
and_exprt(no_overflow_lower, no_overflow_upper),
"arithmetic overflow on signed to unsigned type conversion",
"overflow",
expr.find_source_location(),
expr,
guard);
}
}
else if(old_type.id()==ID_unsignedbv) // unsigned -> unsigned
{
std::size_t old_width=to_unsignedbv_type(old_type).get_width();
if(new_width>=old_width) return; // always ok
binary_relation_exprt no_overflow_upper(ID_le);
no_overflow_upper.lhs()=expr.op0();
no_overflow_upper.rhs()=from_integer(power(2, new_width)-1, old_type);
add_guarded_claim(
no_overflow_upper,
"arithmetic overflow on unsigned to unsigned type conversion",
"overflow",
expr.find_source_location(),
expr,
guard);
}
else if(old_type.id()==ID_floatbv) // float -> unsigned
{
// Note that the fractional part is truncated!
ieee_floatt upper(to_floatbv_type(old_type));
upper.from_integer(power(2, new_width)-1);
binary_relation_exprt no_overflow_upper(ID_lt);
no_overflow_upper.lhs()=expr.op0();
no_overflow_upper.rhs()=upper.to_expr();
ieee_floatt lower(to_floatbv_type(old_type));
lower.from_integer(-1);
binary_relation_exprt no_overflow_lower(ID_gt);
no_overflow_lower.lhs()=expr.op0();
no_overflow_lower.rhs()=lower.to_expr();
add_guarded_claim(
and_exprt(no_overflow_lower, no_overflow_upper),
"arithmetic overflow on float to unsigned integer type conversion",
"overflow",
expr.find_source_location(),
expr,
guard);
}
}
}
}
