Apple Inc.
Prefetch circuit for a processor with pointer optimization

Abstract:

In an embodiment, a processor may implement an access map-pattern match (AMPM)-based prefetch circuit with features designed to improve prefetching accuracy and/or reduce power consumption. In an embodiment, the prefetch circuit may be configured to detect that pointer reads are occurring (e.g. "pointer chasing.") The prefetch circuit may be configured to increase the frequency at which prefetch requests are generated for an access map in which pointer read activity is detected, compared to the frequency at which the prefetch requests would be generated in the pointer read activity is not generated. In an embodiment, the prefetch circuit may also detect access maps that are store-only, and may reduce the frequency of prefetches for store only access maps as compared to the frequency of load-only or load/store maps.