Many register-oriented computer architectures partition the register file(s) into two classes, caller-save and callee-save. Caller-save registers in use at a call site must be explicitly saved prior to the call and restored after the call (since they may be freely used by the subroutine that is to be called). Calleesave
registers that will be used within a subroutine must be saved by the sub routine (prior to executing the subroutine's body) and restored by the subroutine (prior to returning to the caller). By allocating caller-save and calleesave registers carefully, fewer registers may need to be saved across a call. Extend the seven steps of Section 13.2.1 to provide for saving and restoring of both caller-save and callee-save registers.