1. A method for managing data in a cache memory system, the method comprising: assigning relative priority values to at least a subset of data items in the cache memory system, wherein the assigning comprises: identifying one or more regions of code that require prioritized data items; identifying one or more load/store instructions associated with the one or more regions of code; identifying one or more data items accessed by the one or more load/store instructions; and tagging the one or more data items to reflect relative priorities of the one or more data items by executing an address capture load/store instruction that updates priority tag fields of entries in a tag directory that correspond to the one or more data items, wherein the address capture load/store instruction comprises: a priority tag loaded to a priority tag register at a beginning of a given one of the one or more regions of code; and an update priority range instruction inserted at an end of the given one of the one or more regions of code; fetching a new data item to load into the cache memory system, the new data item being associated with a priority value; and selecting an existing data item from the cache memory system to replace with the new data item, in accordance with the relative priority values and the priority value associated with the new data item.