Data store access circuitry is disclosed that comprises: a data store for storing values; comparator circuitry coupled to said data store and responsive to receipt of a data access request comprising an address to compare at least a portion of said address with at least a portion of one or more of said values stored in said data store so as to identify a stored value matching said address; a base value register coupled to said comparator circuitry and storing a base value corresponding to at least a portion of at least one of said stored values; and comparator control circuitry coupled to said comparator circuitry to control: (i) which portion of said address is processed as a non-shared portion and compared by said comparator circuitry with non-shared portions of said one or more stored values stored in said data store; and (ii) which portion of said address is processed as a shared portion and compared by said comparator circuitry with a shared portion of said base value stored in said base value register; wherein said shared portion of said base value has a value matching corresponding portions of all of said stored values stored within said data store.