Apple Inc.
Branch resolve pointer optimization

Abstract:

A system and method for efficiently handling speculative execution. A load store unit (LSU) of a processor stores a commit candidate pointer, which points to a given store instruction buffered in the store queue. The given store instruction is an oldest store instruction not currently permitted to commit to the data cache. The LSU receives a first pointer from the mapping unit, which points to an oldest instruction of non-dispatched branches and unresolved system instructions. The LSU receives a second pointer from the execution unit, which points to an oldest unresolved, issued branch instruction. When the LSU determines the commit candidate pointer is older than each of the first pointer and the second pointer, the commit candidate pointer is updated to point to an oldest store instruction younger than the given store instruction stored in the store queue. The given store instruction is permitted to commit to the data cache.