Arm Limited

Geoffray Lacourba

Alex James Waugh

Natalya Bondarenko

Albin Pierrick Tonnerre

Luca Nassi

Cédric Denis Robert Airaud

Bruce James Mathewson

Phanindra Kumar Mannava

Andrew John Turner

Jamshed Jalal

Abhishek Raja

Michael Filippo

Paul Gilbert Meyer

Frederic Claude Marie Piry

Klas Magnus Bruce

Lucas Garcia

Stefano Ghiggini

Paolo Monti

Yohan Fernand Fargeix

Quentin Éric Nouvel

Miles Robert Dooley

Sergio Schuler

Philippe Jean-Pierre Raphalen

Huzefa Moiz Sanjeliwala

Fergus Wilson MacGarry

Nathanael Premillieu

Luca Maroncelli

Kias Magnus Bruce

Nicola Piano

Ilaria Bosco

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.

Allocation of store buffer entries

An apparatus is provided. Delegable memory accesses are offloaded to be performed by an external processing apparatus, whereas non-delegable memory accesses are performed locally. Nonetheless, an ordering requirement may still be enforced between them. The apparatus comprises tracking circuitry to maintain tracking information related to delegable memory accesses separately from tracking information related to non-delegable memory accesses. Order enforcement circuitry may enforce an ordering requirement between a non-delegable memory access and a delegable memory access based on a lookup of the tracking information.

Order enforcement for delegable memory accesses

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. For an operation specifying a given architectural register of the first set of architectural registers: in response to a determination that the operation is to be processed in the first mode of processing, the register mapping circuitry maps the given architectural register to a physical register of a first physical register file, and in response to a determination that the operation is to be processed in the second mode of processing, the register mapping circuitry maps the given architectural register to a physical register of a second physical register file separate from the first physical register file and having physical registers of different register length to physical registers of the first physical register file.

Register mapping to map architectural registers to corresponding physical registers based on a mode indicating a register length

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.

Cracking instructions into a plurality of micro-operations

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.

Controlling data allocation to storage circuitry

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.

Register freeing latency

A data processing apparatus comprises receiver circuitry for receiving instructions from each of a plurality of requester devices. Processing circuitry executes the instructions associated with each of a subset of the requester devices at a time and arbitration circuitry determines the subset of the requester devices and causes the instructions associated with each of the subset of the requester devices to be executed next. In response to the receiver circuitry receiving an instruction of a predetermined type from one of the requester devices outside the subset of requester devices, the arbitration circuitry causes the instruction of the predetermined type to be executed next.

Shared unit instruction execution

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.

Data processing apparatus and method for generating prefetches based on a nested prefetch pattern

A technique is provided for training a prediction apparatus. The apparatus has an input interface for receiving a sequence of training events indicative of program instructions, and identifier value generation circuitry for performing an identifier value generation function to generate, for a given training event received at the input interface, an identifier value for that given training event. The identifier value generation function is arranged such that the generated identifier value is dependent on at least one register referenced by a program instruction indicated by that given training event. Prediction storage is provided with a plurality of training entries, where each training entry is allocated an identifier value as generated by the identifier value generation function, and is used to maintain training data derived from training events having that allocated identifier value. Matching circuitry is then responsive to the given training event to detect whether the prediction storage has a matching training entry (i.e. an entry whose allocated identifier value matches the identifier value for the given training event). If so, it causes the training data in the matching training entry to be updated in dependence on the given training event.

Technique for training a prediction apparatus

Data processing apparatus comprises a data access requesting node; data access circuitry to receive a data access request from the data access requesting node and to route the data access request for fulfilment by one or more data storage nodes selected from a group of two or more data storage nodes; and indication circuitry to provide a source indication to the data access requesting node, to indicate an attribute of the one or more data storage nodes which fulfilled the data access request; the data access requesting node being configured to vary its operation in response to the source indication.

Data processing

Apparatus and a corresponding method of operating a hub device, and a target device, in a coherent interconnect system are presented. A cache pre-population request of a set of coherency protocol transactions in the system is received from a requesting master device specifying at least one data item and the hub device responds by cause a cache pre-population trigger of the set of coherency protocol transactions specifying the at least one data item to be transmitted to a target device. This trigger can cause the target device to request that the specified at least one data item is retrieved and brought into cache. Since the target device can therefore decide whether to respond to the trigger or not, it does not receive cached data unsolicited, simplifying its configuration, whilst still allowing some data to be pre-cached.

Cache content management

Circuitry comprises a data store to hold status data indicating a status of a first set of one or more devices connected to the interconnect circuitry; and control circuitry, responsive to initiation of a data handling transaction, to generate recovery data indicative of an initial state of the status data and to predict a predicted revised state of the status data applicable to resolution of the data handling transaction; the control circuitry being configured to change the status data to the predicted revised state in response to initiation of the transaction and before resolution of the transaction, and in response to a request to access the status data between the change of the status data to the predicted revised state and the resolution of the transaction, to provide access to the initial state of the status data, using the recovery data.

Generating recovery data for an initial state of status data for a data handling transaction and predicting a revised state of the status data applicable to resolution of the data handling transaction

An interconnect apparatus comprises first node circuitry for performing first node operations to service data access requests in respect of a first range of memory addresses and second node circuitry for performing second node operations to service data access requests in respect of a second range of memory addresses. The interconnect comprises interface circuitry to: receive a retry indication in respect of a data access request from the first node and forward the retry indication to the requester circuitry; responsive to determining that the interface circuitry has capacity for the data access request, transmit a reissue capacity message to the requester circuitry; receive a reissued data access request from the requester circuitry; and issue the reissued data access request to the second node circuitry. The second node circuitry is responsive to receiving the reissued data access request to service the data access request.

Methods and apparatus for reconfiguring nodes and reissuing data access requests

Aspects of the present disclosure relate to an interconnect comprising an interface to couple to a master device, the interface comprising buffer storage. The interface is configured to receive a request from the master device for data comprising a plurality of data blocks, the master device requiring the data blocks in a defined order. A data collator is configured to: receive the request; issue a data pull request to cause the interface to allocate buffer space in the buffer storage for buffering the requested data; and responsive to receiving a confirmation that the buffer space is allocated, provide the requested data to the buffer storage. The interface is configured to employ the buffer storage to enable re-ordering of the plurality of data blocks of the requested data, prior to outputting the plurality of data blocks to the master device; and output the plurality of data blocks to the master device in the defined order.

Apparatus and method for providing data to a master device

An interconnect is provided that has a plurality of nodes, and a ring network to which each of the nodes is connected to allow packets to be transmitted between nodes. For an ordered sequence of packets one of the nodes is arranged as a source node to add each packet of the ordered sequence on to the ring network, and another of the nodes is arranged as a destination node to remove each packet of the ordered sequence from the ring network. The source node is enabled to add a packet of the ordered sequence on to the ring network without waiting for a previously added packet of the ordered sequence to be removed from the ring network by the destination node. When the destination node is unable to accept a given packet of the ordered sequence that is currently being presented to the destination node by the ring network, that given packet remains on the ring network and continues to be transmitted around the ring network such that after a respin period that given packet will be presented again to the destination node. The destination node is then arranged to prevent acceptance of at least any other packets of the ordered sequence subsequently presented to the destination node by the ring network until the destination node has accepted the given packet following at least one respin period. This can improve the efficiency of the ring network in the handling of ordered sequences of packets, whilst still ensuring the ordering constraints are met.

Growing community of inventors

Nice, France

Geoffray Lacourba