Return Sequence

. Callee places a return value next to activation record of caller

. Restores registers using information in status field

. Branch to return address

. Caller copies return value into its own activation record

As described earlier, in the runtime stack, the activation record of the caller is just below that for the callee. The fields for parameters and a potential return value are placed next to the activation record of the caller. The caller can then access these fields using offsets from the end of its own activation record. The caller copies the return value into its own activation record. In particular, there is no reason for the caller to know about the local data or temporaries of the callee. The given calling sequence allows the number of arguments of the called procedure to depend on the call. At compile time, the target code of the caller knows the number of arguments it is supplying to the callee. The caller knows the size of the parameter field. The target code of the called must be prepared to handle other calls as well, so it waits until it is called, then examines the parameter field. Information describing the parameters must be placed next to the status field so the callee can find it.