Scheduler which retries load/store hit situations

Abstract

A scheduler issues memory operations without regard to whether or not resources are available to handle each possible execution outcome of that memory operation. The scheduler also retains the memory operation after issuance. If a condition occurs which prevents correct execution of the memory operation, the memory operation is retried. The scheduler subsequently reschedules and reissues the memory operation in response to the retry. Additionally, the scheduler may receive a retry type indicating the reason for retry. Certain retry types may indicate a delayed reissuance of the memory operation until the occurrence of a subsequent event. In response to such retry types, the scheduler monitors for the subsequent event and delays reissuance until the event is detected. The scheduler may include a physical address buffer to detect a load memory operation which incorrectly issued prior to an older store memory operation upon which it is dependent for the memory operation. The scheduler may also include a store tag buffer to detect that a load memory operation is to be reissued due to the reissuance of a store memory operation on which the load was determined to be dependent during the previous execution of the load memory operation.