Instruction issue manner and the device null which expect ahead

摘要

A system for scheduling instruction issuance in a vector register computer achieves increased efficiency of operation by performing pre-issuance checks to determine if resources requested by the instruction will be available when the instruction issues. A decoding apparatus first determines particular resources requested by the instruction, which includes apparatus for decoding vector register requests, functional unit requests, and address and scalar register path requests. Following decoding, a conflict resolution apparatus checks resource reservation flags to determine if the requested resources will be available when the instruction issues. If any requested resources will be busy, the system issues a primary conflict signal. At the scheduled instruction issuance time, the system again checks the resource reservation flags in response to the primary conflict signal. If the requested resources are still busy, the system generates a secondary conflict signal for as long as the requested resources remain busy. Finally, when the instruction issues, the system sets the resource reservation flags to reserve the requested resources for the instruction.