Abstract: An apparatus is provided for controlling the operating mode of control circuitry, such that the control circuitry may change between two operating modes. In an allocation mode, data that is loaded in response to an instruction is allocated into storage circuitry from an intermediate buffer, and the data is read from the storage circuitry. In a non-allocation mode, the data is not allocated to the storage circuitry, and is read directly from intermediate buffer. The control of the operating mode may be performed by mode control circuitry, and the mode may be changed in dependence on the type of instruction that calls the data, and whether the data may be used again in the near future, or whether it is expected to be used only once.

Abstract: An apparatus comprises a cache to store information, items of information in the cache being associated with addresses; cache lookup circuitry to perform lookups in the cache; and a prefetcher to prefetch items of information into the cache in advance of an access request being received for said items of information. The prefetcher selects addresses to train the prefetcher. In response to determining that a cache lookup specifying a given address has resulted in a hit and determining that a cache lookup previously performed in response to a prefetch request issued by the prefetcher for the given address resulted in a hit, the prefetcher selects the given address as an address to be used to train the prefetcher.

Abstract: Circuitry comprises a memory system to store data items; cache memory storage to store a copy of one or more data items, the cache memory storage comprising a hierarchy of two or more cache levels; detector circuitry to detect at least a property of data items for storage by the cache memory storage; and control circuitry to control eviction, from a given cache level, of a data item stored by the given cache level, the control circuitry being configured to select a destination to store a data item evicted from the given cache level in response to a detection by the detector circuitry.

Abstract: An apparatus comprises a cache to store information, items of information in the cache being associated with addresses; cache lookup circuitry to perform lookups in the cache; and a prefetcher to prefetch items of information into the cache in advance of an access request being received for said items of information. The prefetcher selects addresses to train the prefetcher. In response to determining that a cache lookup specifying a given address has resulted in a hit and determining that a cache lookup previously performed in response to a prefetch request issued by the prefetcher for the given address resulted in a hit, the prefetcher selects the given address as an address to be used to train the prefetcher.

Abstract: The invention provides a data processing apparatus and a data processing method for generating prefetches of data for use during execution of instructions by processing circuitry. The prefetches that are generated are based on a nested prefetch pattern. The nested prefetch pattern comprises a first pattern and a second pattern. The first pattern is defined by a first address offset between sequentially accessed addresses and a first observed number of the sequentially accessed addresses separated by the first address offset. The second pattern is defined by a second address offset between sequential iterations of the first pattern and a second observed number of the sequential iterations of the first pattern separated by the second address offset.

Abstract: Examples of the present disclosure relate to an apparatus comprising processing circuitry to perform data processing operations, storage circuitry to store data for access by the processing circuitry, address translation circuitry to maintain address translation data for translating virtual memory addresses into corresponding physical memory addresses, and prefetch circuitry. The prefetch circuitry is arranged to prefetch first data into the storage circuitry in anticipation of the first data being required for performing the data processing operations. The prefetching comprises, based on a prediction scheme, predicting a first virtual memory address associated with the first data, accessing the address translation circuitry to determine a first physical memory address corresponding to the first virtual memory address, and retrieving the first data based on the first physical memory address corresponding to the first virtual memory address.

Abstract: A technique is described for managing a cache structure in a system employing transactional memory. The apparatus comprises processing circuitry to perform data processing operations in response to instructions, the processing circuitry comprising transactional memory support circuitry to support execution of a transaction, and a cache structure comprising a plurality of cache entries for storing data for access by the processing circuitry. Each cache entry has associated therewith an allocation tag, and allocation tag control circuitry is provided to control use of a plurality of allocation tags and to maintain an indication of a current state of each of those allocation tags.

Abstract: An apparatus comprises processing circuitry, transactional memory support circuitry and a cache. The processing circuitry processes threads of data processing, and the transactional memory support circuitry supports execution of a transaction within a thread, including tracking a read set of addresses, comprising addresses accessed by read instructions within the transaction. A transaction comprises instructions for which the processing circuitry is configured to prevent commitment of the results of speculatively executed instruction until the transaction has completed. The cache has a plurality of entries, each associated with an address and specifying a replaceable-information value for that address that comprises information for which, outside of the transaction, processing would be functionally correct even if the information was incorrect.

Abstract: Examples of the present disclosure relate to an apparatus comprising processing circuitry to perform data processing operations, storage circuitry to store data for access by the processing circuitry, address translation circuitry to maintain address translation data for translating virtual memory addresses into corresponding physical memory addresses, and prefetch circuitry. The prefetch circuitry is arranged to prefetch first data into the storage circuitry in anticipation of the first data being required for performing the data processing operations. The prefetching comprises, based on a prediction scheme, predicting a first virtual memory address associated with the first data, accessing the address translation circuitry to determine a first physical memory address corresponding to the first virtual memory address, and retrieving the first data based on the first physical memory address corresponding to the first virtual memory address.

Abstract: An apparatus comprises processing circuitry, transactional memory support circuitry and a cache. The processing circuitry processes threads of data processing, and the transactional memory support circuitry supports execution of a transaction within a thread, including tracking a read set of addresses, comprising addresses accessed by read instructions within the transaction. A transaction comprises instructions for which the processing circuitry is configured to prevent commitment of the results of speculatively executed instruction until the transaction has completed. The cache has a plurality of entries, each associated with an address and specifying a replaceable-information value for that address that comprises information for which, outside of the transaction, processing would be functionally correct even if the information was incorrect.

Abstract: A technique is described for managing a cache structure in a system employing transactional memory. The apparatus comprises processing circuitry to perform data processing operations in response to instructions, the processing circuitry comprising transactional memory support circuitry to support execution of a transaction, and a cache structure comprising a plurality of cache entries for storing data for access by the processing circuitry. Each cache entry has associated therewith an allocation tag, and allocation tag control circuitry is provided to control use of a plurality of allocation tags and to maintain an indication of a current state of each of those allocation tags.