Signed multiply-subtract long (vector, by element)
This instruction multiplies each vector element in the lower or upper half of the first source SIMD&FP register by the specified vector element of the second source SIMD&FP register 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 vector elements from the lower half of the first source register. The SMLSL2 instruction extracts vector elements from the upper half of the first 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 | 1 | size | L | M | Rm | 0 | 1 | 1 | 0 | H | 0 | Rn | Rd | ||||||||||||
| U | o2 | ||||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_AdvSIMD) then EndOfDecode(Decode_UNDEF); end; let idxdsize : integer{} = 64 << UInt(H); var index : integer; var Rmhi : bit; case size of when '01' => index = UInt(H::L::M); Rmhi = '0'; when '10' => index = UInt(H::L); Rmhi = M; otherwise => EndOfDecode(Decode_UNDEF); end; let d : integer = UInt(Rd); let n : integer = UInt(Rn); let m : integer = UInt(Rmhi::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
|
| <m> |
Is the number of the second SIMD&FP source register,
encoded in
|
| <Ts> |
Is an element size specifier,
encoded in
|
| <index> |
Is the element index,
encoded in
|
AArch64_CheckFPAdvSIMDEnabled(); let operand1 : bits(datasize) = Vpart{}(n, part); let operand2 : bits(idxdsize) = V{}(m); let operand3 : bits(2*datasize) = V{}(d); var result : bits(2*datasize); var element1 : integer; let element2 : integer = SInt(operand2[index*:esize]); var product : bits(2*esize); for e = 0 to elements-1 do element1 = SInt(operand1[e*:esize]); product = (element1 * element2)[2*esize-1:0]; result[e*:(2*esize)] = operand3[e*:(2*esize)] - product; 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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