* control flow nodes need not be known. In case of cyclic control flow these
* can not be known when the block is constructed. With add_immBlock_pred(block,
* cfnode) predecessors can be added to the block. If all predecessors are
* control flow nodes need not be known. In case of cyclic control flow these
* can not be known when the block is constructed. With add_immBlock_pred(block,
* cfnode) predecessors can be added to the block. If all predecessors are