Abstract: An apparatus has cache circuitry providing a cache storage to store data for access by processing circuitry, and request handling circuitry arranged to process requests, each request providing an address indication for associated data. The request handling circuitry determines with reference to the address indication whether the associated data is available in the cache circuitry. The cache circuitry forms a given level of a multi-level memory hierarchy, and the request handling circuitry is responsive to determining that the associated data is unavailable in the cache circuitry to issue an onward request to cause the associated data to be retrieved into the cache circuitry from a lower level of the multi-level memory hierarchy than the given level.

Abstract: An apparatus comprises at least one register rename table structure comprising rename entries for indicating register mappings between architectural registers and corresponding physical registers, and register rename circuitry to update the register mappings indicated by the rename entries. Rename entries corresponding to at least one set of architectural registers support a cleared-register encoding. In response to an operation specifying a source architectural register for which a corresponding rename entry is set to the cleared-register encoding, the register rename circuitry controls the processing circuitry to process that operation with a source operand corresponding to the source architectural register being treated as having a predetermined value.

Abstract: An apparatus comprises a cache; and control circuitry to select at least one cache access transaction to be serviced by the cache from among one or more pending cache access transactions. In response to a cache allocation transaction being selected by the control circuitry for servicing by the cache, the cache is configured to start a cache allocation process for allocating data into the cache for an address not previously having a valid entry in the cache. The control circuitry is configured to determine, based on at least one workload-dependent performance heuristic, whether to cancel a remaining part of an unfinished cache allocation process performed for a given cache allocation transaction already selected for servicing by the cache, to free up bandwidth for servicing another cache access transaction.

Abstract: An apparatus has cache data storage, and tagged-data prediction circuitry to generate a tagged-data prediction in response to a streaming-write request requesting that write data corresponding to a target address which missed in a previous level of cache is written to the cache data storage for the given level of cache without being allocated into the previous level of cache. The tagged-data prediction is indicative of whether a target cache data entry corresponding to the target address of the streaming-write request is predicted to be a tagged cache data entry that stores cached data associated with the target address and a valid memory safety check tag corresponding to the target address, or an untagged cache data entry that stores the cached data but does not store a valid memory safety check tag.

Abstract: Apparatuses, systems, methods, computer-readable media, and computer code are disclosed. An apparatus comprises allocation circuitry configured to allocate store data comprising N portions in a store buffer. The store buffer comprises a data buffer configured to hold data entries, each data entry configured to hold one of the N portions of the store data; and an address buffer configured to hold address entries, wherein a given address entry is indicative of a memory address at which the store data is to be stored and is associated with N indications identifying one or more of the data entries that contain the store data. The allocation circuitry is responsive to a determination that M portions of the N portions of the store data each comprise duplicate data to set M indications of the N indications to identify a given data entry holding the duplicate data.

Abstract: An apparatus has cache data storage, and tagged-data prediction circuitry to generate a tagged-data prediction in response to a streaming-write request requesting that write data corresponding to a target address which missed in a previous level of cache is written to the cache data storage for the given level of cache without being allocated into the previous level of cache. The tagged-data prediction is indicative of whether a target cache data entry corresponding to the target address of the streaming-write request is predicted to be a tagged cache data entry that stores cached data associated with the target address and a valid memory safety check tag corresponding to the target address, or an untagged cache data entry that stores the cached data but does not store a valid memory safety check tag.

Abstract: An apparatus comprises a cache; and control circuitry to select at least one cache access transaction to be serviced by the cache from among one or more pending cache access transactions. In response to a cache allocation transaction being selected by the control circuitry for servicing by the cache, the cache is configured to start a cache allocation process for allocating data into the cache for an address not previously having a valid entry in the cache. The control circuitry is configured to determine, based on at least one workload-dependent performance heuristic, whether to cancel a remaining part of an unfinished cache allocation process performed for a given cache allocation transaction already selected for servicing by the cache, to free up bandwidth for servicing another cache access transaction.

Abstract: Mode change detection circuitry detects a mode change when processing circuitry switches between first and second modes of processing in which a first set of architectural registers are designated as having different register lengths. Register mapping circuitry maps architectural registers to corresponding physical registers.

Abstract: An apparatus has cache circuitry providing a cache storage to store data for access by processing circuitry, and request handling circuitry arranged to process requests, each request providing an address indication for associated data. The request handling circuitry determines with reference to the address indication whether the associated data is available in the cache circuitry. The cache circuitry forms a given level of a multi-level memory hierarchy, and the request handling circuitry is responsive to determining that the associated data is unavailable in the cache circuitry to issue an onward request to cause the associated data to be retrieved into the cache circuitry from a lower level of the multi-level memory hierarchy than the given level.

Abstract: There is provided an apparatus, method for data processing. The apparatus comprises post decode cracking circuitry responsive to receipt of decoded instructions from decode circuitry of a processing pipeline, to crack the decoded instructions into micro-operations to be processed by processing circuitry of the processing pipeline. The post decode cracking circuitry is responsive to receipt of a decoded instruction suitable for cracking into a plurality of micro-operations including at least one pair of micro-operations having a producer-consumer data dependency, to generate the plurality of micro-operations including a producer micro-operation and a consumer micro-operation, and to assign a transfer register to transfer data between the producer micro-operation and the consumer micro-operation.

Abstract: An apparatus comprises at least one register rename table structure comprising rename entries for indicating register mappings between architectural registers and corresponding physical registers, and register rename circuitry to update the register mappings indicated by the rename entries. Rename entries corresponding to at least one set of architectural registers support a cleared-register encoding. In response to an operation specifying a source architectural register for which a corresponding rename entry is set to the cleared-register encoding, the register rename circuitry controls the processing circuitry to process that operation with a source operand corresponding to the source architectural register being treated as having a predetermined value.

Abstract: Mode change detection circuitry detects a mode change when processing circuitry switches between first and second modes of processing in which a first set of architectural registers are designated as having different register lengths. Register mapping circuitry maps architectural registers to corresponding physical registers.

Abstract: There is provided an apparatus, method for data processing. The apparatus comprises post decode cracking circuitry responsive to receipt of decoded instructions from decode circuitry of a processing pipeline, to crack the decoded instructions into micro-operations to be processed by processing circuitry of the processing pipeline. The post decode cracking circuitry is responsive to receipt of a decoded instruction suitable for cracking into a plurality of micro-operations including at least one pair of micro-operations having a producer-consumer data dependency, to generate the plurality of micro-operations including a producer micro-operation and a consumer micro-operation, and to assign a transfer register to transfer data between the producer micro-operation and the consumer micro-operation.

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: A data processing apparatus is provided. Instruction send circuitry sends an instruction to an external processor to be executed by the external processor. Allocation circuitry allocates a specified one of several registers for a result of the instruction having been executed on the external processor and data receive circuitry receives the result of the instruction having been executed on the external processor and stores the result in the specified one of the several registers. In response to a condition being met: the specified one of the several registers is dereserved prior to the result being received by the data receive circuitry, and the result is discarded by the data receive circuitry when the result is received by the data receive circuitry.

Abstract: A data processing apparatus comprises: execution circuitry to execute instructions in order to perform data processing operations specified by those instructions; a plurality of registers to store data values for access by the execution circuitry when performing the data processing operations, each register having an associated physical register identifier; register rename circuitry to select physical register identifiers to associate with architectural register identifiers specified by the instructions; and rename storage having a plurality of entries, each entry being associated with one of the architectural register identifiers and used by the register rename circuitry to indicate a physical register identifier selected for association with that one of the architectural register identifiers; the register rename circuitry comprising an execute unit, and being responsive to detection of an early execute condition for a given instruction, the early execute condition requiring at least detection that each sour

Abstract: A data processing apparatus comprises: execution circuitry to execute instructions in order to perform data processing operations specified by those instructions; a plurality of registers to store data values for access by the execution circuitry when performing the data processing operations, each register having an associated physical register identifier; register rename circuitry to select physical register identifiers to associate with architectural register identifiers specified by the instructions; and rename storage having a plurality of entries, each entry being associated with one of the architectural register identifiers and used by the register rename circuitry to indicate a physical register identifier selected for association with that one of the architectural register identifiers; the register rename circuitry comprising an execute unit, and being responsive to detection of an early execute condition for a given instruction, the early execute condition requiring at least detection that each sour

Abstract: A data processing apparatus is provided. Instruction send circuitry sends an instruction to an external processor to be executed by the external processor. Allocation circuitry allocates a specified one of several registers for a result of the instruction having been executed on the external processor and data receive circuitry receives the result of the instruction having been executed on the external processor and stores the result in the specified one of the several registers. In response to a condition being met: the specified one of the several registers is dereserved prior to the result being received by the data receive circuitry, and the result is discarded by the data receive circuitry when the result is received by the data receive circuitry.

Abstract: Processing circuitry performs processing operations in response to micro-operations. Front end circuitry supplies the micro-operations to be processed by the processing circuitry. Prediction circuitry generates a prediction of a number of loop iterations for which one or more micro-operations per loop iteration are to be supplied by the front end circuitry, where an actual number of loop iterations to be processed by the processing circuitry is resolvable by the processing circuitry based on at least one operand corresponding to a first loop iteration to be processed by the processing circuitry. The front end circuitry varies, based on a level of confidence in the prediction of the number of loop iterations, a supply rate with which the one or more micro-operations for at least a subset of the loop iterations are supplied to the processing circuitry.

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.