Signed saturating doubling multiply-add (bottom × top)
This instruction multiplies the even-numbered signed elements of the first source vector by the corresponding odd-numbered signed elements of the second source vector, and then doubles the result of the multiplication. Each intermediate value is saturated to the double-width N-bit value's signed integer range -2(N-1) to (2(N-1))-1 and is then destructively added to the overlapping double-width elements of the addend and destination vector. Each destination element is saturated to the double-width N-bit element's signed integer range -2(N-1) to (2(N-1))-1. This instruction is unpredicated.
| 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 | Zm | 0 | 0 | 0 | 0 | 1 | 0 | Zn | Zda | |||||||||||||
| S | |||||||||||||||||||||||||||||||
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 n : integer = UInt(Zn); let m : integer = UInt(Zm); let da : integer = UInt(Zda); let sel1 : integer = 0; let sel2 : integer = 1;
| <Zda> |
Is the name of the third source and destination scalable vector register, encoded in the "Zda" field. |
| <T> |
Is the size specifier,
encoded in
|
| <Zn> |
Is the name of the first source scalable vector register, encoded in the "Zn" field. |
| <Tb> |
Is the size specifier,
encoded in
|
| <Zm> |
Is the name of the second source scalable vector register, encoded in the "Zm" field. |
CheckSVEEnabled(); let VL : integer{} = CurrentVL(); let elements : integer = VL DIV esize; let operand1 : bits(VL) = Z{}(n); let operand2 : bits(VL) = Z{}(m); var result : bits(VL) = Z{}(da); for e = 0 to elements-1 do let element1 : integer = SInt(operand1[(2 * e + sel1)*:(esize DIV 2)]); let element2 : integer = SInt(operand2[(2 * e + sel2)*:(esize DIV 2)]); let element3 : integer = SInt(result[e*:esize]); let product : integer = SInt(SignedSat{esize}(2 * element1 * element2)); result[e*:esize] = SignedSat{esize}(element3 + product); end; Z{VL}(da) = result;
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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