static final Map<Class, _MethodCache> callOpt_cache = newDangerousWeakHashMap();

static O callOpt_cached(O o, S methodName, O... args) ctex {
  if (o == null) null;
  
  _MethodCache cache;
    
  if (o instanceof Class) {
    Class c = (Class) o;
    synchronized(callOpt_cache) {
      cache = callOpt_cache.get(c);
      if (cache == null) cache = _MethodCache(c);
    }
    
    // TODO: (super-rare) case where method exists static and non-static
    // with different args
    
    Method me = cache.findMethod(methodName, args);
    if (me == null || (me.getModifiers() && Modifier.STATIC) == 0) null;
    ret invokeMethod(me, null, args);
  } else {
    Class c = o.getClass();
    synchronized(callOpt_cache) {
      cache = callOpt_cache.get(c);
      if (cache == null) cache = _MethodCache(c);
    }
  
    Method me = cache.findMethod(methodName, args);
    if (me == null) null;
    ret invokeMethod(me, o, args);
  }
}