Dot product with unsigned and signed integers (vector)
This instruction performs the dot product of the four unsigned 8-bit integer values in each 32-bit element of the first source register with the four signed 8-bit integer values in the corresponding 32-bit element of the second source register, accumulating the result into the corresponding 32-bit element of the destination register.
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.
| 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 | Q | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | Rm | 1 | 0 | 0 | 1 | 1 | 1 | Rn | Rd | ||||||||||||
| U | size | opcode | |||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_I8MM) then EndOfDecode(Decode_UNDEF); end; let d : integer{} = UInt(Rd); let n : integer{} = UInt(Rn); let m : integer{} = UInt(Rm); let datasize : integer{} = 64 << UInt(Q); let elements : integer = datasize DIV 32;
| <Vd> |
Is the name of the SIMD&FP third source and destination register, encoded in the "Rd" field. |
| <Ta> |
Is an arrangement specifier,
encoded in
|
| <Vn> |
Is the name of the first SIMD&FP source register, encoded in the "Rn" field. |
| <Tb> |
Is an arrangement specifier,
encoded in
|
| <Vm> |
Is the name of the second SIMD&FP source register, encoded in the "Rm" field. |
AArch64_CheckFPAdvSIMDEnabled(); let operand1 : bits(datasize) = V{}(n); let operand2 : bits(datasize) = V{}(m); let operand3 : bits(datasize) = V{}(d); var result : bits(datasize); for e = 0 to elements-1 do var res : bits(32) = operand3[e*:32]; for b = 0 to 3 do let element1 : integer = UInt(operand1[(4 * e + b)*:8]); let element2 : integer = SInt(operand2[(4 * e + b)*:8]); res = res + element1 * element2; end; result[e*:32] = res; end; V{datasize}(d) = result;
This instruction is a data-independent-time instruction as described in About PSTATE.DIT.
2026-03_rel 2026-03-26 20:48:11
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