bvt boolbvt::convert_if(const if_exprt &expr)
{
std::size_t width=boolbv_width(expr.type());
if(width==0)
return bvt(); // An empty bit-vector if.
literalt cond=convert(expr.cond());
const bvt &op1_bv=convert_bv(expr.true_case());
const bvt &op2_bv=convert_bv(expr.false_case());
if(op1_bv.size()!=width || op2_bv.size()!=width)
throw "operand size mismatch for if "+expr.pretty();
return bv_utils.select(cond, op1_bv, op2_bv);
}
void arrayst::add_array_constraints_if(
const index_sett &index_set,
const if_exprt &expr)
{
// we got x=(c?a:b)
literalt cond_lit=convert(expr.cond());
// get other array index applications
// and add c => x[i]=a[i]
// !c => x[i]=b[i]
// first do true case
for(index_sett::const_iterator
it=index_set.begin();
it!=index_set.end();
it++)
{
index_exprt index_expr1;
index_expr1.type()=ns.follow(expr.type()).subtype();
index_expr1.array()=expr;
index_expr1.index()=*it;
index_exprt index_expr2;
index_expr2.type()=ns.follow(expr.type()).subtype();
index_expr2.array()=expr.true_case();
index_expr2.index()=*it;
assert(index_expr1.type()==index_expr2.type());
// add implication
bvt bv;
bv.push_back(prop.lnot(cond_lit));
bv.push_back(convert(equality_exprt(index_expr1, index_expr2)));
prop.lcnf(bv);
}
// now the false case
for(index_sett::const_iterator
it=index_set.begin();
it!=index_set.end();
it++)
{
index_exprt index_expr1;
index_expr1.type()=ns.follow(expr.type()).subtype();
index_expr1.array()=expr;
index_expr1.index()=*it;
index_exprt index_expr2;
index_expr2.type()=ns.follow(expr.type()).subtype();
index_expr2.array()=expr.false_case();
index_expr2.index()=*it;
assert(index_expr1.type()==index_expr2.type());
// add implication
bvt bv;
bv.push_back(cond_lit);
bv.push_back(convert(equality_exprt(index_expr1, index_expr2)));
prop.lcnf(bv);
}
}
