Multi-vector unsigned integer multiply-subtract long long
This instruction multiplies each unsigned 8-bit or 16-bit element in the two or four first source vectors by each unsigned 8-bit or 16-bit element in the one, two, or four second source vectors, widens each product to 32 bits or 64 bits, and destructively subtracts these values from the corresponding 32-bit or 64-bit elements of the ZA quad-vector groups.
The quad-vector group within each half of or each quarter of the ZA array is selected by the sum of the vector select register and offset range, modulo half or quarter the number of ZA array vectors.
The vector group symbol, VGx2 or VGx4, indicates that the ZA operand consists of two or four ZA quad-vector groups respectively. The vector group symbol is preferred for disassembly, but optional in assembler source code.
This instruction is unpredicated.
ID_AA64SMFR0_EL1.I16I64 indicates whether the 16-bit integer variant is implemented.
It has encodings from 2 classes: Two ZA quad-vectors and Four ZA quad-vectors
| 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 |
| 1 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | sz | 1 | Zm | 0 | 0 | Rv | 0 | 0 | 0 | Zn | 0 | 1 | 1 | 0 | 0 | o1 | |||||||
| U | S | op | |||||||||||||||||||||||||||||
UMLSLL ZA.<T>[<Wv>, <offs1>:<offs4>{, VGx2}], { <Zn1>.<Tb>-<Zn2>.<Tb> }, { <Zm1>.<Tb>-<Zm2>.<Tb> }
if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF); end; if sz == '1' && !IsFeatureImplemented(FEAT_SME_I16I64) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 32 << UInt(sz); let v : integer = UInt('010'::Rv); let n : integer = UInt(Zn::'0'); let m : integer = UInt(Zm::'0'); let offset : integer = UInt(o1::'00'); let nreg : integer{} = 2;
| 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 |
| 1 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | sz | 1 | Zm | 0 | 1 | 0 | Rv | 0 | 0 | 0 | Zn | 0 | 0 | 1 | 1 | 0 | 0 | o1 | |||||
| U | S | op | |||||||||||||||||||||||||||||
UMLSLL ZA.<T>[<Wv>, <offs1>:<offs4>{, VGx4}], { <Zn1>.<Tb>-<Zn4>.<Tb> }, { <Zm1>.<Tb>-<Zm4>.<Tb> }
if !IsFeatureImplemented(FEAT_SME2) then EndOfDecode(Decode_UNDEF); end; if sz == '1' && !IsFeatureImplemented(FEAT_SME_I16I64) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 32 << UInt(sz); let v : integer = UInt('010'::Rv); let n : integer = UInt(Zn::'00'); let m : integer = UInt(Zm::'00'); let offset : integer = UInt(o1::'00'); let nreg : integer{} = 4;
| <T> |
Is the size specifier,
encoded in
|
| <Wv> |
Is the 32-bit name of the vector select register W8-W11, encoded in the "Rv" field. |
| <offs1> |
Is the first vector select offset, encoded as "o1" field times 4. |
| <offs4> |
Is the fourth vector select offset, encoded as "o1" field times 4 plus 3. |
| <Tb> |
Is the size specifier,
encoded in
|
| <Zn2> |
Is the name of the second scalable vector register of the first source multi-vector group, encoded as "Zn" times 2 plus 1. |
| <Zm2> |
Is the name of the second scalable vector register of the second source multi-vector group, encoded as "Zm" times 2 plus 1. |
| <Zn4> |
Is the name of the fourth scalable vector register of the first source multi-vector group, encoded as "Zn" times 4 plus 3. |
| <Zm4> |
Is the name of the fourth scalable vector register of the second source multi-vector group, encoded as "Zm" times 4 plus 3. |
CheckStreamingSVEAndZAEnabled(); let VL : integer{} = CurrentVL(); let elements : integer = VL DIV esize; let vectors : integer = VL DIV 8; let vstride : integer = vectors DIV nreg; let vbase : bits(32) = X{}(v); var vec : integer = (UInt(vbase) + offset) MOD vstride; var result : bits(VL); vec = vec - (vec MOD 4); for r = 0 to nreg-1 do let operand1 : bits(VL) = Z{}(n+r); let operand2 : bits(VL) = Z{}(m+r); for i = 0 to 3 do let operand3 : bits(VL) = ZAvector{}(vec + i); for e = 0 to elements-1 do let element1 : integer = UInt(operand1[(4 * e + i)*:(esize DIV 4)]); let element2 : integer = UInt(operand2[(4 * e + i)*:(esize DIV 4)]); let product : bits(esize) = (element1 * element2)[esize-1:0]; result[e*:esize] = operand3[e*:esize] - product; end; ZAvector{VL}(vec + i) = result; end; vec = vec + vstride; end;
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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