Pipeline processor, with return address stack storing only pre- return processed addresses for judging validity and correction of unprocessed address

摘要

A data processor in accordance with the present invention makes it possible to perform pre-branch processing with respect to a return address in the initial stage of pipeline processing also on a subroutine return instruction, and therefore by providing a stack memory (PC stack) dedicated to a program counter (PC) for storing only return addresses of the subroutine return instruction, in executing a subroutine call instruction in an execution stage of a pipeline processing mechanism, the return address from the subroutine is pushed to the PC stack, and the pre- branch processing is performed to the address popped from the PC stack in decoding the subroutine return instruction in an instruction decoding stage.