/// PHIElimination pass - This pass eliminates machine instruction PHI nodes
/// by inserting copy instructions. This destroys SSA information, but is the
/// desired input for some register allocators. This pass is "required" by
/// these register allocator like this: AU.addRequiredID(PHIEliminationID);
///
/// PHIElimination pass - This pass eliminates machine instruction PHI nodes
/// by inserting copy instructions. This destroys SSA information, but is the
/// desired input for some register allocators. This pass is "required" by
/// these register allocator like this: AU.addRequiredID(PHIEliminationID);
///