Signed add and accumulate long pairwise
This instruction adds pairs of adjacent signed integer values and accumulates the results into the overlapping double-width elements of the destination vector.
| 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 | 0 | 1 | 0 | 0 | size | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | Pg | Zn | Zda | |||||||||||
| U | |||||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SVE2) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; if size == '00' then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let g : integer = UInt(Pg); let n : integer = UInt(Zn); let da : integer = UInt(Zda);
| <Zda> |
Is the name of the second source and destination scalable vector register, encoded in the "Zda" field. |
| <T> |
Is the size specifier,
encoded in
|
| <Pg> |
Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field. |
| <Zn> |
Is the name of the first source scalable vector register, encoded in the "Zn" field. |
| <Tb> |
Is the size specifier,
encoded in
|
CheckSVEEnabled(); let VL : integer{} = CurrentVL(); let PL : integer{} = VL DIV 8; let elements : integer = VL DIV esize; let mask : bits(PL) = P{}(g); let operand_acc : bits(VL) = Z{}(da); let operand_src : bits(VL) = if AnyActiveElement{PL}(mask, esize) then Z{VL}(n) else Zeros{VL}; var result : bits(VL); for e = 0 to elements-1 do if !ActivePredicateElement{PL}(mask, e, esize) then result[e*:esize] = operand_acc[e*:esize]; else let element1 : integer = SInt(operand_src[(2*e + 0)*:(esize DIV 2)]); let element2 : integer = SInt(operand_src[(2*e + 1)*:(esize DIV 2)]); let sum : bits(esize) = (element1 + element2)[esize-1:0]; result[e*:esize] = operand_acc[e*:esize] + sum; end; end; Z{VL}(da) = result;
This instruction is a data-independent-time instruction as described in About PSTATE.DIT.
This instruction might be immediately preceded in program order by a MOVPRFX instruction. The MOVPRFX must conform to all of the following requirements, otherwise the behavior of the MOVPRFX and this instruction is CONSTRAINED UNPREDICTABLE:
2026-03_rel 2026-03-26 20:48:11
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