EXPAND

Copy lower-numbered vector elements to Active elements

This instruction copies consecutive elements from the source vector to Active elements of the destination vector, in increasing order of element number. Inactive elements in the destination vector register are set to zero.

This instruction is illegal when executed in Streaming SVE mode, unless FEAT_SME_FA64 is implemented and enabled, or FEAT_SME2p2 is implemented.

SVE2
(FEAT_SVE2p2 || FEAT_SME2p2)

313029282726252423222120191817161514131211109876543210
00000101size110001100PgZnZd

Encoding

EXPAND <Zd>.<T>, <Pg>, <Zn>.<T>

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE2p2) && !IsFeatureImplemented(FEAT_SME2p2) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let g : integer = UInt(Pg); let n : integer = UInt(Zn); let d : integer = UInt(Zd);

Assembler Symbols

<Zd>

Is the name of the destination scalable vector register, encoded in the "Zd" field.

<T>

Is the size specifier, encoded in size:

size <T>
00 B
01 H
10 S
11 D
<Pg>

Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field.

<Zn>

Is the name of the source scalable vector register, encoded in the "Zn" field.

Operation

if IsFeatureImplemented(FEAT_SME2p2) then CheckSVEEnabled(); else CheckNonStreamingSVEEnabled(); end; 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}; var result : bits(VL); var x : integer = 0; for e = 0 to elements-1 do if ActivePredicateElement{PL}(mask, e, esize) then result[e*:esize] = operand1[x*:esize]; x = x + 1; else result[e*:esize] = Zeros{esize}; end; end; Z{VL}(d) = result;


2026-03_rel 2026-03-26 20:48:11

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