Arm Limited

Neil Burgess

David Raymond Lutz

Christopher Neal Hinds

Lee Evan Eisen

Nigel John Stephens

Michael Alexander Kennedy

Mbou Eyole

Zichao Xie

Gary Alan Gorman

Daniel Arulraj

Andreas Due Engh-Halstvedt

Pranay Prabhat

Grigorios Magklis

Kelvin Domnic Goveas

Jacob Eapen

Chiloda Ashan Senarath Pathirane

Javier Diaz Bruguera

Karel Hubertus Gerardus Walters

Jaime Ferragut Martinez-Vara De Rey

Sabrina Marie Romero

Pedro Olsen Ferreira

An apparatus includes a processing circuit and a storage device. The processing circuit is configured to perform one or more processing operations in response to one or more instructions to generate an anchored-data element. The storage device is configured to store the anchored-data element. A format of the anchored-data element includes an identification item, an overlap item, and a data item. The data item is configured to hold a data value of the anchored-data element. The identification item indicates an anchor value for the data value or one or more special values.

High-precision anchored-implicit processing

Vector add-with-carry instructions are described which use some elements of a destination vector register, or corresponding fields of a predicate register, to provide the carry information corresponding to results of an add-with-carry operation. This is useful for accelerating computations involving multiplications of long integer values.

Vector add-with-carry instruction

An apparatus comprises: processing circuitry, an instruction decoder, and registers. In response to an overlapped-immediate/register-field-specifying (OIRFS) instruction comprising an opcode field specifying an OIRFS-indicating opcode value, and an overlapped immediate/register field specifying an immediate value and a register specifier, the instruction decoder controls the processing circuitry to use a selected register of the plurality of registers corresponding to the register specifier as a source register or destination register when performing a processing operation depending on the immediate value. The overlapped immediate/register field includes at least one shared bit decoded as part of the immediate value for at least one encoding of the OIRFS instruction and decoded as part of the register specifier for at least one encoding of the OIRFS instruction.

Overlapped-immediate/register-field-specifying instruction

Data processing apparatus comprises processing circuitry to selectively apply vector processing operations to one or more data items of one or more data vectors each comprising an ordered plurality of data items at respective vector positions in the data vector, according to the state of respective predicate indicators associated with the vector positions; predicate generation circuitry to apply a processing operation to generate an ordered set of predicate indicators, each associated with a respective one of the vector positions, the ordered set of predicate indicators being associated with an ordered set of active indicators each having an active or an inactive state; and a detector to detect a status flag indicative of whether a predicate indicator at a position, in the ordered set of predicate indicators, corresponding to the position of an outermost active indicator having the active state, has a given state; in which the detector comprises: first and second circuitry to combine the ordered set of predicate indicators and the ordered set of active indicators using first and second respective logical bit-wise combinations to generate first and second ordered sets of intermediate data; and arithmetic circuitry to combine the first and second ordered sets of intermediate data using an arithmetic combination generating a carry bit, the detector generating the status flag in dependence upon the carry bit.

Data processing apparatus and method for generating a status flag using predicate indicators

A multiplier circuit is described in which sub-products calculated in a first stage of a carry-save adder (CSA) network are output early, processed by applying a processing function, and re-injected into a subsequent stage of the CSA network to add the processed sub-products. This allows a CSA network provided for multiplication operations to be reused for operations which require sub-products to be processed and added, such as floating-point dot product operations performed on floating-point values represented in bfloatl6 format.

Multiplier circuit

An in-order processor has a mapping storage element to store current register mapping information identifying, for each of two or more architectural register specifiers, which physical register specifies valid data for that architectural register specifier. At least one checkpoint storage element stores checkpoint register mapping corresponding to a checkpoint of previous architectural state. This enables checkpoints to be saved and restored simply by transferring mapping information between the mapping and checkpoint storage elements, rather than transferring the actual state data.

Checkpointing of architectural state for in order processing circuitry

Processing circuitry selectively applies vector processing operations to one or more data items of one or more data vectors. Each data vector comprises a plurality of data items at respective vector positions in the data vector according to the state of respective predicate indicators associated with the vector positions. Predicate generation circuitry apply a processing operation to generate a set of predicate indicators, each associated with a respective one of the vector positions, to generate a count value indicative of the number of predicate indicators in the set having a given state, and to store the generated set of predicate indicators and the count value in a predicate store.

Predicate indicator generation for vector processing operations

An apparatus is provided, that includes an instruction decoder responsive to an anchored-data processing instruction, to generate one or more control signals. Conversion circuitry is responsive to the one or more control signals to perform a conversion from a data value to an anchored-data select value. The conversion is based on anchor metadata indicative of a given range of significance for the anchored-data select value. Output circuitry is responsive to the one or more control signals, to write the anchored-data select value to a register.

Anchored data element conversion

Processing circuitry may support processing of anchor-data values comprising one or more anchored-data elements which represent portions of bits of a two's complement number. The anchored-data processing may depend on anchor information indicating at least one property indicative of a numeric range representable by the result anchored-data element or the anchored-data value. When the operation causes an overflow or an underflow, usage information may be stored indicating a cause of the overflow or underflow and/or an indication of how to update the anchor information and/or number of elements in the anchored-data value to prevent the overflow or underflow. This can support dynamic range adjustment in software algorithms which involve anchored-data processing.

Overflow or underflow handling for anchored-data value

A configurable SIMD multiplication circuit is provided to perform multiplication on a multiplicand operand M and multiplier operand R with varying data element sizes supported. For each result element generated based on corresponding elements of the multiplicand operand M and the multiplier operand R, the multiplication is performed according to radix-N modified Booth multiplication, where N=2and P&#x2265;3. A Booth digit selection scheme is described for improving the efficiency with which higher radix modified Booth multiplication can be implemented in a configurable SIMD multiplier.

Configurable SIMD multiplication circuit

An apparatus and method are provided for efficiently performing arithmetic operations that include at least a multiplication operation. The apparatus comprises processing circuitry to perform data processing operations, and instruction decode circuitry responsive to program instructions to generate control signals to control the processing circuitry to perform the data processing operations. In response to an arithmetic operation with shift instruction specifying performance of an arithmetic operation comprising at least a multiplication operation, and having a field which provides a programmable shift indication, the instruction decode circuitry is configured to control the processing circuitry to perform the arithmetic operation during which an intermediate value is produced, and to select a target portion of the intermediate value based on an output window determined from the programmable shift indication.

Arithmetic operation with shift

An apparatus and method are provided for processing input operand values. The apparatus has a set of vector data storage elements, each vector data storage element providing a plurality of sections for storing data values. A plurality of lanes are considered to be provided within the set of storage elements, where each lane comprises a corresponding section from each vector data storage element. Processing circuitry is arranged to perform an arithmetic operation on an input operand value comprising a plurality of portions, by performing an independent arithmetic operation on each of the plurality of portions, in order to produce a result value comprising a plurality of result portions. Storage circuitry is arranged to store the result value within a selected lane of the plurality of lanes, such that each result portion is stored in a different vector data storage element within the corresponding section for the selected lane. Such an approach allows efficient processing of input operand values in a manner that is not constrained by the size of the vector data storage elements, and in particular in a way that is vector length agnostic.

Apparatus and method for processing input operand values

Processing circuitry is provided for comparing a number of adjacent widths having a common value and extending from a starting position within an input number with a runlength specified by a variable number. The circuitry includes a mask generator for generating a mask value in dependence upon the variable number, combination circuitry for performing a logical combination operation upon respective bits within the input number starting from the starting position and corresponding bits within the mask value so as to generate an intermediate value. Result circuitry then generates a result indicative of whether or not the number of adjacent bits is less than or equal to the run length in dependence upon a determination if any bits within the intermediate value have a predetermined value.

Comparing a runlength of bits with a variable number

An apparatus comprises: processing circuitry to perform data processing; and an instruction decoder to control the processing circuitry to perform an anchored-data processing operation to generate an anchored-data element. The anchored-data element has an encoding including type information indicative of whether the anchored-data element represents: a portion of bits of a two's complement number, said portion of bits corresponding to a given range of significance representable using the anchored-data element; or a special value other than said portion of bits of a two's complement number.

Encoding special value in anchored-data element

An apparatus and method are provided for performing multiply-and-accumulate-products (MAP) operations. The apparatus has processing circuitry for performing data processing, the processing circuitry including an adder array having a plurality of adders for accumulating partial products produced from input operands. An instruction decoder is provided that is responsive to a MAP instruction specifying a first J-bit operand and a second K-bit operand, to control the processing circuitry to enable performance of a number of MAP operations, where the number is dependent on a parameter. For each performed MAP operation, the processing circuitry is arranged to generate a corresponding result element representing a sum of respective E&#xd7;F products of E-bit portions within an X-bit segment of the first operand with F-bit portions within a Y-bit segment of the second operand, where E&#x3c;X&#x2264;J and F&#x3c;Y&#x2264;K. In response to the MAP instruction, the instruction decoder is configured to control the processing circuitry to perform a rearrangement operation to rearrange the portions of at least one of the first operand and the second operand to form transformed first and second operands so that the E&#xd7;F products that are required to be summed are aligned with a number of columns of adders within the adder array. Further, the adder array is controlled in dependence on the transformed first and second operands to add the required E&#xd7;F products using the number of columns of adders within the adder array. Further, the rearrangement performed by the rearrangement operation is controlled in dependence on the parameter such that at least one column of adders used when the parameter indicates the first number of MAP operations is reused when the parameter indicates a second number of MAP operations different to the first number. This provides a particularly area and power efficient implementation for handling MAP operations.

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Austin, TX, United States of America

Neil Burgess