Count matching elements in vector
This instruction compares each active 32 or 64-bit element of the first source vector with all Active elements with an element number less than or equal to its own in the second source vector, and places the count of matching elements in the corresponding element of the destination vector. Inactive elements in the destination vector are set to zero.
This instruction is illegal when executed in Streaming SVE mode, unless FEAT_SME_FA64 is implemented and enabled.
| 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 | 1 | size | 1 | Zm | 1 | 1 | 0 | Pg | Zn | Zd | |||||||||||||||
if !IsFeatureImplemented(FEAT_SVE2) then EndOfDecode(Decode_UNDEF); end; if size IN {'0x'} then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let g : integer = UInt(Pg); let d : integer = UInt(Zd); let n : integer = UInt(Zn); let m : integer = UInt(Zm);
| <Zd> |
Is the name of the destination scalable vector register, encoded in the "Zd" 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. |
| <Zm> |
Is the name of the second source scalable vector register, encoded in the "Zm" field. |
CheckNonStreamingSVEEnabled(); let VL : integer{} = CurrentVL(); let PL : integer{} = VL DIV 8; let elements : integer = VL DIV esize; let mask : bits(PL) = P{}(g); let operand1 : bits(VL) = if AnyActiveElement{PL}(mask, esize) then Z{VL}(n) else Zeros{VL}; let operand2 : bits(VL) = if AnyActiveElement{PL}(mask, esize) then Z{VL}(m) else Zeros{VL}; var result : bits(VL); for e = 0 to elements-1 do var count : integer = 0; if ActivePredicateElement{PL}(mask, e, esize) then let element1 : bits(esize) = operand1[e*:esize]; for i = 0 to e do if ActivePredicateElement{PL}(mask, i, esize) then let element2 : bits(esize) = operand2[i*:esize]; if element1 == element2 then count = count + 1; end; end; end; end; result[e*:esize] = count[esize-1:0]; end; Z{VL}(d) = result;
2026-03_rel 2026-03-26 20:48:11
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