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## SMMLA (vector)

Signed 8-bit integer matrix multiply-accumulate. This instruction multiplies the 2x8 matrix of signed 8-bit integer values in the first source vector by the 8x2 matrix of signed 8-bit integer values in the second source vector. The resulting 2x2 32-bit integer matrix product is destructively added to the 32-bit integer matrix accumulator in the destination vector. This is equivalent to performing an 8-way dot product per destination element.

From Armv8.2 to Armv8.5, this is an OPTIONAL instruction. From Armv8.6 it is mandatory for implementations that include Advanced SIMD to support it. ID_AA64ISAR1_EL1.I8MM indicates whether this instruction is supported.

### Vector
(FEAT_I8MM)

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
0 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | Rm | 1 | 0 | 1 | 0 | 0 | 1 | Rn | Rd
| Q | U |  | size |  |  |  | B |  |  |

####

SMMLA <Vd>.4S, <Vn>.16B, <Vm>.16B

if !IsFeatureImplemented(FEAT_I8MM) then UNDEFINED; integer n = UInt(Rn); integer m = UInt(Rm); integer d = UInt(Rd);

### Assembler Symbols

<Vd> | Is the name of the SIMD&FP third source and destination register, encoded in the "Rd" field.

<Vn> | Is the name of the first SIMD&FP source register, encoded in the "Rn" field.

<Vm> | Is the name of the second SIMD&FP source register, encoded in the "Rm" field.

### Operation

CheckFPAdvSIMDEnabled64(); bits(128) operand1 = V[n, 128]; bits(128) operand2 = V[m, 128]; bits(128) addend = V[d, 128]; V[d, 128] = MatMulAdd(addend, operand1, operand2, FALSE, FALSE);

### Operational information

Arm expects that the SMMLA (vector) instruction will deliver a peak integer multiply throughput that is at least as high as can be achieved using two SDOT (vector) instructions, with a goal that it should have significantly higher throughput.

Base Instructions | SIMD&FP Instructions | SVE Instructions | SME Instructions | Index by Encoding | Shared Pseudocode | Proprietary Notice

Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45

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