  Modern compiler implementations use the Static Single Assignment
representation as a way to efficiently implement optimizing algorithms. However
this representation is not well adapted to architectures with a predicated
instruction set. The Psi-SSA representation extends the SSA representation such
that standard SSA algorithms can be easily adapted to an architecture with a
fully predicated instruction set. A new pseudo operation, the Psi operation, is
introduced to merge several conditional definitions into a unique definition.
