void boolbvt::convert_index(const index_exprt &expr, bvt &bv)
{
if(expr.id()!=ID_index)
throw "expected index expression";
if(expr.operands().size()!=2)
throw "index takes two operands";
const exprt &array=expr.array();
const exprt &index=expr.index();
const array_typet &array_type=
to_array_type(ns.follow(array.type()));
// see if the array size is constant
if(is_unbounded_array(array_type))
{
// use array decision procedure
unsigned width=boolbv_width(expr.type());
if(width==0)
return conversion_failed(expr, bv);
// free variables
bv.resize(width);
for(unsigned i=0; i<width; i++)
bv[i]=prop.new_variable();
record_array_index(expr);
// record type if array is a symbol
if(array.id()==ID_symbol)
map.get_map_entry(
to_symbol_expr(array).get_identifier(), array_type);
// make sure we have the index in the cache
convert_bv(index);
return;
}
// see if the index address is constant
mp_integer index_value;
if(!to_integer(index, index_value))
return convert_index(array, index_value, bv);
unsigned width=boolbv_width(expr.type());
if(width==0)
return conversion_failed(expr, bv);
mp_integer array_size;
if(to_integer(array_type.size(), array_size))
{
std::cout << to_array_type(array.type()).size().pretty() << std::endl;
throw "failed to convert array size";
}
// get literals for the whole array
const bvt &array_bv=convert_bv(array);
if(array_size*width!=array_bv.size())
throw "unexpected array size";
// TODO: maybe a shifter-like construction would be better
if(prop.has_set_to())
{
// free variables
bv.resize(width);
for(unsigned i=0; i<width; i++)
bv[i]=prop.new_variable();
// add implications
equal_exprt index_equality;
index_equality.lhs()=index; // index operand
bvt equal_bv;
equal_bv.resize(width);
for(mp_integer i=0; i<array_size; i=i+1)
{
index_equality.rhs()=from_integer(i, index_equality.lhs().type());
if(index_equality.rhs().is_nil())
throw "number conversion failed (1)";
mp_integer offset=i*width;
for(unsigned j=0; j<width; j++)
equal_bv[j]=prop.lequal(bv[j],
array_bv[integer2long(offset+j)]);
prop.l_set_to_true(
prop.limplies(convert(index_equality), prop.land(equal_bv)));
}
}
else
{
bv.resize(width);
equal_exprt equality;
equality.lhs()=index; // index operand
typet constant_type=index.type(); // type of index operand
assert(array_size>0);
for(mp_integer i=0; i<array_size; i=i+1)
{
equality.op1()=from_integer(i, constant_type);
literalt e=convert(equality);
mp_integer offset=i*width;
for(unsigned j=0; j<width; j++)
{
literalt l=array_bv[integer2long(offset+j)];
if(i==0) // this initializes bv
bv[j]=l;
else
bv[j]=prop.lselect(e, l, bv[j]);
}
}
}
}
void arrayst::collect_arrays(const exprt &a)
{
const array_typet &array_type=
to_array_type(ns.follow(a.type()));
if(a.id()==ID_with)
{
if(a.operands().size()!=3)
throw "with expected to have three operands";
// check types
if(!base_type_eq(array_type, a.op0().type(), ns))
{
std::cout << a.pretty() << std::endl;
throw "collect_arrays got with without matching types";
}
arrays.make_union(a, a.op0());
collect_arrays(a.op0());
// make sure this shows as an application
index_exprt index_expr;
index_expr.type()=array_type.subtype();
index_expr.array()=a.op0();
index_expr.index()=a.op1();
record_array_index(index_expr);
}
else if(a.id()==ID_if)
{
if(a.operands().size()!=3)
throw "if expected to have three operands";
// check types
if(!base_type_eq(array_type, a.op1().type(), ns))
{
std::cout << a.pretty() << std::endl;
throw "collect_arrays got if without matching types";
}
// check types
if(!base_type_eq(array_type, a.op2().type(), ns))
{
std::cout << a.pretty() << std::endl;
throw "collect_arrays got if without matching types";
}
arrays.make_union(a, a.op1());
arrays.make_union(a, a.op2());
collect_arrays(a.op1());
collect_arrays(a.op2());
}
else if(a.id()==ID_symbol)
{
}
else if(a.id()==ID_nondet_symbol)
{
}
else if(a.id()==ID_member)
{
if(to_member_expr(a).struct_op().id()!=ID_symbol)
throw "unexpected array expression: member with `"+a.op0().id_string()+"'";
}
else if(a.id()==ID_constant ||
a.id()==ID_array ||
a.id()==ID_string_constant)
{
}
else if(a.id()==ID_array_of)
{
}
else
throw "unexpected array expression: `"+a.id_string()+"'";
}