void bv_minimizet::operator()(const minimization_listt &symbols)
{
// build bit-wise objective function
prop_minimizet prop_minimize(boolbv);
prop_minimize.set_message_handler(get_message_handler());
for(minimization_listt::const_iterator
l_it=symbols.begin();
l_it!=symbols.end();
l_it++)
{
add_objective(prop_minimize, *l_it);
}
// now solve
prop_minimize();
}
void counterexample_beautificationt::get_minimization_list(
prop_convt &prop_conv,
const symex_target_equationt &equation,
minimization_listt &minimization_list)
{
// ignore the ones that are assigned under false guards
for(symex_target_equationt::SSA_stepst::const_iterator
it=equation.SSA_steps.begin();
it!=equation.SSA_steps.end(); it++)
{
if(it->is_assignment() &&
it->assignment_type==symex_targett::assignment_typet::STATE)
{
if(!prop_conv.l_get(it->guard_literal).is_false())
{
const typet &type=it->ssa_lhs.type();
if(type!=bool_typet())
{
// we minimize the absolute value, if applicable
if(type.id()==ID_signedbv ||
type.id()==ID_fixedbv ||
type.id()==ID_floatbv)
{
abs_exprt abs_expr(it->ssa_lhs);
minimization_list.insert(abs_expr);
}
else
minimization_list.insert(it->ssa_lhs);
}
}
}
// reached failed assertion?
if(it==failed)
break;
}
}
bool bv_minimizing_dect::minimize(const minimization_listt &symbols)
{
// unfortunately, only MiniSat supports this
#if defined(SATCHECK_MINISAT) || defined(SATCHECK_MINISAT2)
bvt constraints;
for(minimization_listt::const_iterator
l_it=symbols.begin();
l_it!=symbols.end();
l_it++)
{
unsigned result=0;
const exprt &symbol = *l_it;
status("Minimizing... ");
// FIXME: be more gener[ous|al] here!
assert(symbol.type().id()==ID_unsignedbv);
unsigned width=boolbv_width(symbol.type());
for(unsigned i = width; i > 0; i--)
{
literalt lit;
#if 0
std::cout << "SYMBOL: " << symbol << std::endl;
#endif
if(literal(symbol, i-1, lit))
continue; // there's no corresponding literal
if(lit.is_constant())
continue;
literalt nlit=satcheck.lnot(lit);
constraints.push_back(nlit);
if(satcheck.l_get(lit)==tvt(false))
continue;
// call Minisat with constraints
satcheck.set_assumptions(constraints);
if(satcheck.prop_solve() == propt::P_UNSATISFIABLE)
{
// change constraint to 1
constraints.back().swap(lit);
result |= 1 << (i-1);
// make sure the model is reconstructed
satcheck.set_assumptions(constraints);
if(satcheck.prop_solve()==propt::P_UNSATISFIABLE)
assert (false); // do not remove call to prop_solve!!
}
}
status(symbol.get_string(ID_identifier)+" = "+i2string(result));
}
return true;
#else
// we don't have it...
return false;
#endif
}
