static bool is_skip(goto_programt::instructionst::iterator it)
{
if (it->is_skip())
return true;
if (it->is_goto())
{
if (is_constant_bool2t(it->guard) &&
!to_constant_bool2t(it->guard).constant_value)
return true;
if (it->targets.size()!=1)
return false;
goto_programt::instructionst::iterator next_it=it;
next_it++;
return it->targets.front()==next_it;
}
if(it->is_other())
{
return is_nil_expr(it->code);
}
return false;
}
static bool is_skip(goto_programt::instructionst::iterator it)
{
// we won't remove labelled statements
// (think about error labels or the like)
if(!it->labels.empty())
return false;
if(it->is_skip())
return !it->code.get_bool(ID_explicit);
if(it->is_goto())
{
if(it->guard.is_false()) return true;
if(it->targets.size()!=1)
return false;
goto_programt::instructionst::iterator next_it=it;
next_it++;
// a branch to the next instruction is a skip
return it->targets.front()==next_it;
}
if(it->is_other())
{
if(it->code.is_nil()) return true;
const irep_idt &statement=it->code.get_statement();
if(statement==ID_skip)
return true;
else if(statement==ID_expression)
{
const code_expressiont &code_expression=to_code_expression(it->code);
const exprt &expr=code_expression.expression();
if(expr.id()==ID_typecast &&
expr.type().id()==ID_empty &&
to_typecast_expr(expr).op().is_constant())
{
// something like (void)0
return true;
}
}
return false;
}
return false;
}
