Signed multiply-subtract long (vector)
This instruction multiplies corresponding signed integer values in the lower or upper half of the vectors of the two source SIMD&FP registers, and subtracts the results from the vector elements of the destination SIMD&FP register. The destination vector elements are twice as long as the elements that are multiplied.
The SMLSL instruction extracts each source vector from the lower half of each source register. The SMLSL2 instruction extracts each source vector from the upper half of each source register.
Depending on the settings in the CPACR_EL1, CPTR_EL2, and CPTR_EL3 registers, and the current Security state and Exception level, an attempt to execute the instruction might be trapped.
| 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 | size | 1 | Rm | 1 | 0 | 1 | 0 | 0 | 0 | Rn | Rd | |||||||||||||
| U | o1 | ||||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_AdvSIMD) then EndOfDecode(Decode_UNDEF); end; if size == '11' then EndOfDecode(Decode_UNDEF); end; let d : integer{} = UInt(Rd); let n : integer{} = UInt(Rn); let m : integer{} = UInt(Rm); let esize : integer{} = 8 << UInt(size); let datasize : integer{} = 64; let part : integer = UInt(Q); let elements : integer = datasize DIV esize;
| <Vd> |
Is the name of the SIMD&FP 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) = Vpart{}(n, part); let operand2 : bits(datasize) = Vpart{}(m, part); let operand3 : bits(2*datasize) = V{}(d); var result : bits(2*datasize); var element1 : integer; var element2 : integer; var product : bits(2*esize); var accum : bits(2*esize); for e = 0 to elements-1 do element1 = SInt(operand1[e*:esize]); element2 = SInt(operand2[e*:esize]); product = (element1 * element2)[2*esize-1:0]; accum = operand3[e*:(2*esize)] - product; result[e*:(2*esize)] = accum; end; V{2*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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