US Patent 7562192 Microprocessor, apparatus and method for selective prefetch retire

An apparatus in a microprocessor for selectively retiring a prefetched cache line is disclosed. The microprocessor includes a prefetch buffer that stores a cache line prefetched from a system memory coupled to the microprocessor. The microprocessor also includes a cache memory, comprising an array of storage elements for storing cache lines, indexed by an index input. One of the storage elements of the array indexed by an index portion of an address of the prefetched cache line stored in the prefetch buffer is storing a replacement candidate line for the prefetched cache line. The microprocessor also includes control logic that determines whether the replacement candidate line in the cache memory is invalid, and if so, replaces the replacement candidate line in the one of the storage elements with the prefetched cache line from the prefetch buffer.