Alternative.java

    public long readLong(VirtualFrame vframe) {
        return readLongHelper(vframe.materialize());
    }

    @TruffleBoundary
    public long readLongHelper(MaterializedFrame vframe) {
        try {
            return vframe.getLong(getSlot());
        } catch (FrameSlotTypeException e) { }
        MaterializedFrame frame = getLexicalScope(vframe);
        while (true) {
            try {
                return frame.getLong(getSlot());
            } catch (FrameSlotTypeException e) {
                frame = getLexicalScope(frame);
                if (frame == null) {
                    throw new RuntimeException("Undefined variable " + getSlot().getIdentifier());
                }
            }
        }
    }