marshal.c:913
static void
r_ivar(obj, arg)
    VALUE obj;
    struct load_arg *arg;
{
    long len;

    len = r_long(arg);
    if (len > 0) {
	while (len--) {
	    ID id = r_symbol(arg);
	    VALUE val = r_object(arg);
	    rb_ivar_set(obj, id, val);
	}
    }
}
