Arm Limited

The Chancellor, Masters and Scholars of the University of Cambridge

Giacomo Gabrielli

Balaji Venu

Mbou Eyole

Mbou Eyole-Monono

Matthew James Horsnell

Matthias Lothar Boettcher

Matthew James Walker

Alastair David Reid

Timothy Hayes

Syed Ali Mustafa Zaidi

Richard Roy Grisenthwaite

Wei Wang

Nigel John Stephens

Frederic Claude Marie Piry

Peter Richard Greenhalgh

Ian Michael Caulfield

Albin Pierrick Tonnerre

Damian Piotr Modrzyk

Metin Gokhan Ünal

Roko Grubisic

Matthias Lothar Böttcher

Peng Sun

Timothy Martin Jones

There is provided a data processing apparatus and method. The data processing apparatus comprises a plurality of processing elements connected via a network arranged on a single chip to form a spatial architecture. Each processing element comprising processing circuitry to perform processing operations and memory control circuitry to perform data transfer operations and to issue data transfer requests for requested data to the network. The memory control circuitry is configured to monitor the network to retrieve the requested data from the network. Each processing element is further provided with local storage circuitry comprising a plurality of local storage sectors to store data associated with the processing operations, and auxiliary memory control circuitry to monitor the network to detect stalled data (S). The auxiliary memory control circuitry is configured to transfer the stalled data from the network to an auxiliary storage buffer (S) dynamically selected from amongst the plurality of local storage sectors (S).

Data processing apparatus and method for handling stalled data

Provided is a data stream processor comprising a streamed data transceiver interface, a structure of processing units configurable to transform data received from a data source over the streamed data transceiver interface according to a specified output requirement, and a configuration unit operable in electronic communication with a data consumer to receive an output requirement and to configure the operation and linkage of a processing unit in the structure of processing units to transform input data to output data according to the specified output requirement; wherein the structure of processing units is further operable to provide the output data for output over the streamed data transceiver interface.

Data stream processor

Circuitry comprises processing circuitry configured to execute program instructions in dependence upon respective trigger conditions matching a current trigger state and to set a next trigger state in response to program instruction execution; the processing circuitry comprising: instruction storage configured to selectively provide a group of two or more program instructions for execution in parallel; and trigger circuitry responsive to the generation of a trigger state by execution of program instructions and to a trigger condition associated with a given group of program instructions, to control the instruction storage to provide program instructions of the given group of program instructions for execution.

Circuitry and method for instruction execution in dependence upon trigger conditions

A data processing apparatus and a method for processing data are disclosed. The data processing apparatus comprises: multithreaded processing circuitry to perform processing operations of a plurality of micro-threads, each micro-thread operating in a corresponding execution context defining an architectural state. Thread control circuitry collects runtime data indicative of a performance metric relating to the processing operations. Decoder circuitry is responsive to a detach instruction in a first micro-thread of instructions executed in a first execution context defining a first architectural state, the detach instruction specifying an address, to provide detach control signals to the thread control circuitry. When the runtime data meet a parallelization criterion, the thread control circuitry is responsive to the detach control signals to spawn a second micro-thread of instructions executed in a second execution context defining a second architectural state based on the first architectural state, the second micro-thread of instructions comprising a subset of instructions of the first micro-thread of instructions starting at the address.

In-core parallelization in a data processing apparatus and method

A data processing apparatus is provided which controls the use of data in respect of a further operation. The data processing apparatus identifies whether data is trusted or untrusted by identifying whether or not the data was determined by a speculatively executed resolve-pending operation. A permission control unit is also provided to control how the data can be used in respect of a further operation according to a security policy while the speculatively executed operation is still resolve-pending.

Controlling use of data determined by a resolve-pending speculative operation

An apparatus and method are provided for speculatively vectorising program code. The apparatus includes processing circuitry for executing program code, the program code including an identified code region comprising at least a plurality of speculative vector memory access instructions. Execution of each speculative vector memory access instruction is employed to perform speculative vectorisation of a series of scalar memory access operations using a plurality of lanes of processing. Tracking storage is used to maintain, for each speculative vector memory access instruction, tracking information providing an indication of a memory address being accessed within each lane. Checking circuitry then references the tracking information during execution of the identified code region by the processing circuitry, in order to detect any inter lane memory hazard resulting from the execution of the plurality of speculative vector memory access instructions.

Apparatus and method for speculatively vectorising program code

One or more triggered-instruction processing elements are provided, a given triggered-instruction processing element comprising execution circuitry to execute processing operations in response to instructions according to a triggered instruction architecture. Input channel processing circuitry receives a given tagged data item (comprising a data value and a tag value) for a given input channel, and in response controls enqueuing of the data value of the given tagged data item to a selected buffer structure selected from among at least two buffer structures mapped onto register storage accessible to one or more of the triggered-instruction processing elements in response to a computation instruction for controlling performance of a computation operation. The selected buffer structure is selected based at least on the tag value, so data values of tagged data items specifying different tag values for the given input channel are allocatable to different buffer structures.

Input channel processing for triggered-instruction processing element

An apparatus, method and computer program, the apparatus comprising processing circuitry to execute instructions, issue circuitry to issue the instructions for execution by the processing circuitry, and candidate instruction storage circuitry to store a plurality of condition-dependent instructions, each specifying at least one condition. The issue circuitry is configured to issue a given condition-dependent instruction in response to a determination or a prediction of the at least one condition specified by the given condition-dependent instruction being met, and when the given condition-dependent instruction is a sequence-start instruction, the issue circuitry is responsive to the determination or prediction to issue a sequence of instructions comprising the sequence-start instruction and at least one subsequent instruction.

Issuing a sequence of instructions including a condition-dependent instruction

There is provided an apparatus, method and medium for data processing. The apparatus comprises a register file comprising a plurality of data registers, and frontend circuitry responsive to an issued instruction, to control processing circuitry to perform a processing operation to process an input data item to generate an output data item. The processing circuitry is responsive to a first encoding of the issued instruction specifying a data register, to read the input data item from the data register, and/or write the output data item to the data register. The processing circuitry is responsive to a second encoding of the issued instruction specifying a buffer-region of the register file for storing a queue of data items, to perform the processing operation and to perform a dequeue operation to dequeue the input data item from the queue, and/or perform an enqueue operation to enqueue the output data item to the queue.

Processing of issued instructions

An apparatus and method are provided for monitoring events in a data processing system. The apparatus has first event monitoring circuitry for monitoring occurrences of a first event within a data processing system, and for asserting a first signal to indicate every m-th occurrence of the first event, where m is an integer of 1 or more. In addition second event monitoring circuitry is used to monitor occurrences of a second event within the data processing system, and to assert a second signal to indicate every n-th occurrence of the second event, where n is an integer of 1 or more. History maintenance circuitry then maintains event history information which is updated in dependence on the asserted first and second signals. Further, history analysis circuitry is responsive to an analysis trigger to analyse the event history information in order to detect a reporting condition when the event history information indicates that a ratio between occurrences of the first event and the occurrences of the second event is outside an acceptable range. The history analysis circuitry is then responsive to detection of the reporting condition to assert a report signal. This provides a particularly efficient and effective mechanism for monitoring ratios of events within a data processing system.

Apparatus and method for monitoring events in a data processing system

Circuitry comprises decode circuitry to decode program instructions including producer instructions and consumer instructions, a consumer instruction requiring, as an input operand, a result generated by execution of a producer instruction; and execution circuitry to execute the program instructions; in which: the decode circuitry is configured to control operation of the execution circuitry in response to hint data associated with a given producer instruction and indicating, for the given producer instruction, a number of consumer instructions which require, as an input operand, a result generated by the given producer instruction.

Circuitry and methods

An apparatus comprises processing circuitry to perform data processing and instruction decoding circuitry to decode instructions to control the processing circuitry to perform the data processing. The instruction decoding circuitry is responsive to a speculation barrier instruction to control the processing circuitry to prevent a subsequent operation, appearing in program order after the speculation barrier instruction, that has an address dependency on an earlier instruction preceding the speculation barrier instruction in the program order, from speculatively influencing allocations of entries in a cache. This provides protection against speculative cache-timing side-channel attacks.

Speculation barrier instruction

Processing circuitry supports a first type of vector arithmetic instruction specifying at least a first input vector. When at least one exceptional condition is detected for an arithmetic operation performed for a first active data element of the first input vector in a predetermined sequence, the processing circuitry performs at least one response action. When the at least one exceptional condition is detected for a given active data element other than the first active data element in the predetermined sequence, the processing circuitry suppresses the at least one response action and stores elements identifying information identifying which data element is the given active data element which triggered the exceptional condition. This can be useful for reducing the amount of hardware resource for tracking the occurrence of the exceptional conditions and/or supporting speculative execution of vector instructions.

Handling exceptional conditions for vector arithmetic instruction

A data processing apparatus has processing circuitry for processing vector operands from a vector register store in response to vector micro-operations, some of which have control information identifying which data elements of the vector operands are selected for processing. Control circuitry detects vector micro-operations for which the control information specifies that a portion of the vector operand to be processed has no selected elements. If this is the case, then the control circuitry controls the processing circuitry to process a lower latency replacement micro-operation instead of the original micro-operation. This provides better performance than if a branch instruction is used to bypass the micro-operation if there are no selected elements.

Data processing apparatus and method for processing vector operands

A vector scan operation is performed to generate M data elements of a result vector, where each result data element corresponds to a combination of an additional data element S with at least some of the data elements of a source vector operand V. The vector scan operation is performed using a plurality of steps, each step comprising one or more combination operations for combining data elements. At least one of the steps includes two or more combination operations performed in parallel. At least two of the steps comprise a combination operation for combining a data element with the additional data element S. This approach enables the vector scan operation to be performed in fewer steps in the case where fewer than M data elements are active, so that the vector scan operation can be performed more quickly.

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Cambridge, United Kingdom

Giacomo Gabrielli