+/**
+ * Internal constructor of a Phi node by a phi_merge operation.
+ *
+ * @param irg the graph on which the Phi will be constructed
+ * @param block the block in which the Phi will be constructed
+ * @param mode the mod eof the Phi node
+ * @param in the input array of the phi node
+ * @param ins number of elements in the input array
+ * @param phi0 in non-NULL: the Phi0 node in the same block that represents
+ * the value for which the new Phi is constructed
+ */