Access map-pattern match based prefetch unit for a processor

Abstract

In an embodiment, a processor may implement an access map-pattern match (AMPM)-based prefetcher in which patterns may include wild cards for some cache blocks. The wild card may match any access for the corresponding cache block (e.g. no access, demand access, prefetch, successful prefetch, etc.). Furthermore, patterns with irregular strides and/or irregular access patterns may be included in the matching patterns and may be detected for prefetch generation. In an embodiment, the AMPM prefetcher may implement a chained access map for large streaming prefetches. If a stream is detected, the AMPM prefetcher may allocate a pair of map entries for the stream and may reuse the pair for subsequent access map regions within the stream. In some embodiments, a quality factor may be associated with each access map and may control the rate of prefetch generation.