Abstract: A data processing apparatus has processing circuitry for processing threads each having thread state data. The threads may be processed in thread groups, with each thread group comprising a number of threads processed in parallel with a common program executed for each thread. Several thread state storage regions are provided with fixed number of thread state entries for storing thread state data for a corresponding thread. At least two of the storage regions have different fixed numbers of entries. The processing circuitry processes as the same thread group threads having thread state data stored in the same storage region and processes threads having thread state data stored in different storage regions as different thread groups.

Abstract: A single instruction multiple thread (SIMT) processor 2 includes execution circuitry 6, prefetch circuitry 12 and prefetch strategy selection circuitry 14. The prefetch strategy selection circuitry serves to detect one or more characteristics of a stream of program instructions that are being executed to identify whether or not a given data access instruction within a program will be executed a plurality of times. The prefetch strategy to use is selected from a plurality of selectable prefetch strategy in dependence upon the detection of such characteristics.

Abstract: A single instruction multiple thread (SIMT) processor 2 includes scheduling circuitry 8 for calculating a next scheduled execution point for execution circuits 4 which execute respective threads corresponding to a common program. In addition to calculating the next scheduled execution point, the scheduling circuitry determines a runner up execution point which would have been determined as the next scheduled execution point if the threads which actually correspond to the next scheduled execution point had been removed from consideration. This runner up execution point is used to identify points of re-convergence within the program flow and as part of the operation of a static branch predictor 10.

Abstract: An apparatus and method are provided for performing register renaming. Available register identifying circuitry is provided to identify which physical registers form a pool of physical registers available to be mapped by register renaming circuitry to an architectural register specified by an instruction to be executed. Configuration data whose value is modified during operation of the processing circuitry is stored such that, when the configuration data has a first value, the configuration data identifies at least one architectural register of the architectural register set which does not require mapping to a physical register by the register renaming circuitry. The register identifying circuitry is arranged to reference the modified data value, such that when the configuration data has the first value, the number of physical registers in the pool is increased due to the reduction in the number of architectural registers which require mapping to physical registers.

Abstract: An apparatus and method are provided for performing register renaming, whereby architectural registers from a set of architectural registers are mapped to physical registers from a set of physical registers. Available register identifying circuitry is provided which is responsive to a current state of the apparatus to identify which physical registers form a pool of physical registers available to be mapped by register renaming circuitry to an architectural register specified by an instruction to be executed. Configuration storage stores configuration data whose value is modified during operation of the processing circuitry, such that when the configuration data has a first value, the configuration data identifies at least one architectural register of the architectural register set which does not require mapping to a physical register by the register renaming circuitry.

Abstract: Processing circuitry executes hypervisor software to support the execution of multiple virtual machines on the processing circuitry. A memory system stores data for access by the processing circuitry and includes secure memory and non-secure memory . The secure memory is only accessible via a secure access request. Address translation circuitry is responsive to an access request issued by a current virtual machine specifying a virtual address, to perform an address translation process to identify a physical address in the memory, and to cause a modified access request to be issued to the memory system specifying the physical address. The hypervisor software sets a trusted virtual machine identifier if the current virtual machine is to be trusted to access the secure memory. The address translation circuitry can only cause the modified access request to be issued as a secure access request to the secure memory if the trusted identifier is set.

Abstract: A method and apparatus for processing data in which a function is processed using a processor operable to perform a plurality of functions is disclosed. When an interrupt is received during processing of the function at a point during the processing at which a portion of the function has been processed then a control parameter is accessed. In response to the control parameter having a value indicting that the function has idempotence processing of the function is stopped without processing the function further, and information on progress of the function is discarded such that following completion of the interrupt the portion of the function that has already been processed is processed again.

Abstract: A data processing apparatus 12 is provided with a memory management unit 24 which triggers memory aborts. When a memory abort occurs, data characterizing the memory abort is written to a fault status register 28 (memory-abort register). The data characterizing the memory abort includes data identifying a register number associated with the memory access which gave rise to the memory abort. This register identifying data is used to emulate the action of the memory access instruction without having to read the program instruction lead to the memory abort. This is useful in providing virtualization support for a virtual data processing apparatus 2.

Abstract: A data processing apparatus has address translation circuitry which is responsive to an access request specifying a virtual address, to perform a multi-stage address translation process to produce, via at least one intermediate address, a physical address in memory corresponding to the virtual address. The address translation circuitry references a storage unit, with each entry of the storage unit storing address translation information for one or more virtual addresses. Each entry has a field indicating whether the address translation information is consolidated address translation information or partial address translation information. If when processing an access request, it is determined that the relevant entry in the storage unit provides consolidated address translation information, the address translation circuitry produces a physical address directly from the consolidated address translation information.

Abstract: A method of processing data comprising: processing a function using a processor operable to perform a plurality of functions, the processor having interrupts enabled; receiving an interrupt at the processor; suspending processing of the function; accessing at least one control parameter, the at least one control parameter indicating whether processing of the function should be resumed from the point where it was interrupted or whether the function should be repeated following the interrupt; following completion of the interrupt continuing processing of the function either at a start of the function or at a point at which it was interrupted dependent upon the control parameter. A function being an application, a thread, a system software routine, or multiple processing steps defined by software.

Abstract: There is provided a processor operable in a first domain and a second domain, the processor comprising: monitoring logic operable to monitor the processor and capture diagnostic data; a storage element operable to contain at least one control parameter; control logic operable to control the monitoring logic in dependence on the at least one control parameter and the domain in which the processor is operating, to suppress capturing of diagnostic data relating to predetermined activities of the processor in the first domain. In some embodiments the first domain is a secure domain and the second domain is a non-secure domain, the monitoring function being debug or trace.

Abstract: An apparatus and method are provided for performing register renaming, whereby architectural registers from a set of architectural registers are mapped to physical registers from a set of physical registers. Available register identifying circuitry is provided which is responsive to a current state of the apparatus to identify which physical registers form a pool of physical registers available to be mapped by register renaming circuitry to an architectural register specified by an instruction to be executed. Configuration storage stores configuration data whose value is modified during operation of the processing circuitry, such that when the configuration data has a first value, the configuration data identifies at least one architectural register of the architectural register set which does not require mapping to a physical register by the register renaming circuitry.

Abstract: Address translation circuitry for translating virtual addresses to physical addresses for a data processor in response to access requests from said data processor targeting virtual addresses is disclosed.

Abstract: A data processing apparatus, and method of managing at least one cache within such an apparatus, are provided. The data processing apparatus has at least one processing unit for executing a sequence of instructions, with each such processing unit having a cache associated therewith, each cache having a plurality of cache lines for storing data values for access by the associated processing unit when executing the sequence of instructions. Identification logic is provided which, for each cache, monitors data traffic within the data processing apparatus and based thereon generates a preferred for eviction identification identifying one or more of the data values as preferred for eviction. Cache maintenance logic is then arranged, for each cache, to implement a cache maintenance operation during which selection of one or more data values for eviction from that cache is performed having regard to any preferred for eviction identification generated by the identification logic for data values stored in that cache.

Abstract: The data processing apparatus has processing logic for performing data processing operations and a register bank for storing data associated with the processing logic. The register bank has at least one register group, each register group having a plurality of register sets. The processing logic has an operating state associated with each register group defining how that register group is used, a first operating state being a state in which each register set in the register group is used to support an independent execution thread of the processing logic, and a second operating state being a state in which the register sets of the register group are collectively used to support a single execution thread of the processing logic. Control logic is provided to control how the register sets of each register group are used dependent on the operating state associated with that register group.

Abstract: A data processing apparatus, and method of managing at least one cache within such an apparatus, are provided. The data processing apparatus has at least one processing unit for executing a sequence of instructions, with each such processing unit having a cache associated therewith, each cache having a plurality of cache lines for storing data values for access by the associated processing unit when executing the sequence of instructions. Identification logic is provided which, for each cache, monitors data traffic within the data processing apparatus and based thereon generates a preferred for eviction identification identifying one or more of the data values as preferred for eviction. Cache maintenance logic is then arranged, for each cache, to implement a cache maintenance operation during which selection of one or more data values for eviction from that cache is performed having regard to any preferred for eviction identification generated by the identification logic for data values stored in that cache.

Abstract: A superscalar data processing apparatus and method are provided for processing operations, the apparatus having a plurality of execution threads and each execution thread being operable to process a sequence of operations including at least one memory access operation. The superscalar data processing apparatus comprises a plurality of execution pipelines for executing the operations, and issue logic for allocating each operation to one of the execution pipelines for execution by that execution pipeline. At least two of the execution pipelines are memory access capable pipelines which can execute memory access operations, and each memory access capable pipeline is associated with a subset of the plurality of execution threads. The issue logic is arranged, for each execution thread, to allocate any memory access operations of that execution thread to an associated memory access capable pipeline.

Abstract: A data processing apparatus 12 is provided with a memory management unit 24 which triggers memory aborts. When a memory abort occurs, data characterising the memory abort is written to a fault status register 28 (memory-abort register). The data characterising the memory abort includes data identifying a register number associated with the memory access which gave rise to the memory abort. This register identifying data is used to emulate the action of the memory access instruction without having to read the program instruction lead to the memory abort. This is useful in providing virtualisation support for a virtual data processing apparatus 2.

Abstract: A processor may utilise two operating systems (Non-Secure, Secure) between which calls may be made. In order that a second operating system can track task switches made by a first operating system, each time a call is made to the second operating system, this call includes an identifier to enable discrimination between the task which was executing on the first operating system when that call was made. The identifier can be a call identifier and/or a target thread identifier and may include further parameters.

Abstract: A data processing apparatus is provided comprising processing logic for issuing access requests when access to data is required, with each access request specifying a memory address associated with the data the subject of the access request. Access control logic is used to perform an access control operation to check for each access request whether the specified memory address is accessible by the processing logic. Further, a table is provided having a plurality of entries, each entry identifying an address range and an associated action. On occurrence of one or more predetermined events, the access control logic references the table to determine whether the specified address is within the address range identified by an entry of the table. If so, the associated action specified in that entry is invoked, whereas otherwise the access control logic causes any action indicated by the access control operation to be performed.