if (((ValFrame) o)._fr != null && _locked.contains(((ValFrame) o)._fr._key)) return;
for(Vec v: ((ValFrame) o)._fr.vecs()) subRef(v);
}
private void addRef(Vec v) {
IcedInt I = _refcnt.get(v);
assert I==null || I._val>0;
_refcnt.put(v,new IcedInt(I==null?1:I._val+1));
//TODO: Does masterVec() need to become public?
// if (v.masterVec()!=null) addRef(vec.masterVec());
}