Store-to-load forwarding correctness checks using physical address proxies stored in load queue entries

Abstract

A microprocessor includes a load/store unit that performs store-to-load forwarding, a PIPT L2 set-associative cache, a store queue having store entries, and a load queue having load entries. Each L2 entry is uniquely identified by a set index and a way. Each store/load entry holds, for an associated store/load instruction, a store/load physical address proxy (PAP) for a store/load physical memory line address (PMLA). The store/load PAP specifies the set index and the way of the L2 entry into which a cache line specified by the store/load PMLA is allocated. Each load entry also holds associated load instruction store-to-load forwarding information. The load/store unit compares the store PAP with the load PAP of each valid load entry whose associated load instruction is younger in program order than the store instruction and uses the comparison and associated forwarding information to check store-to-load forwarding correctness with respect to each younger load instruction.