1. A computer-implemented method for a &PHgr; function providing a mechanism for single static assignment in the presence of predicated code, the method comprising the steps of: introducing an associated ordered guard on each source operand in a control or predicate &PHgr; instruction; materializing a &PHgr; function by inserting at least one copy from each source operand to a target variable in the same order as said source operand; and predicating each of said copies by said ordered guard associated with said source operand.