Data processing apparatus and method for generating prefetches

A method of processing data comprising:

• storing local copies of data items for use during execution of instructions by processing circuitry;
• storing, in a producer pattern history table, a plurality of producer-consumer relationships, each producer-consumer relationship defining an association between producer load indicator and a plurality of consumer load entries, each consumer load entry comprising a consumer load indicator and one or more usefulness metrics;
• initiating, in response to a data load from an address corresponding to the producer load indicator in the producer pattern history table and when at least one of the corresponding one or more usefulness metrics associated with the producer load indicator meets a criterion, a producer prefetch of data to be prefetched for storing as a local copy;
• and
• issuing, when the data is returned, one or more consumer prefetches, each consumer prefetch to return corresponding consumer data from a corresponding consumer address generated from the data returned by the producer prefetch and a corresponding consumer load indicator of a corresponding consumer load entry.

A data processing apparatus comprising:

• means for storing local copies of data items for use during execution of instructions by processing circuitry;
• means for storing, in a producer pattern history table, a plurality of producer-consumer relationships, each producer-consumer relationship defining an association between producer load indicator and a plurality of consumer load entries, each consumer load entry comprising consumer load indicator and one or more usefulness metrics;
• means for initiating, in response to a data load from an address corresponding to the producer load indicator in the producer pattern history table and when at least one of the corresponding one or more usefulness metrics associated with the producer load indicator meets a criterion, a producer prefetch of data to be prefetched into the means for storing based on the data load;
• and
• means for issuing, when the data is returned, one or more consumer prefetches, each consumer prefetch to return corresponding consumer data from a corresponding consumer address generated from the data returned by the producer prefetch and a corresponding consumer load indicator of a corresponding consumer load entry.