DUP (indexed)

Broadcast indexed element to vector (unpredicated)

This instruction unconditionally broadcasts the indexed source vector element into each element of the destination vector. This instruction is unpredicated.

The immediate element index is in the range of 0 to 63 (bytes), 31 (halfwords), 15 (words), 7 (doublewords) or 3 (quadwords). Selecting an element beyond the accessible vector length causes the destination vector to be set to zero.

This instruction is used by the alias MOV (SIMD&FP scalar, unpredicated).

SVE
(FEAT_SVE || FEAT_SME)

313029282726252423222120191817161514131211109876543210
00000101imm21tsz001000ZnZd

Encoding

DUP <Zd>.<T>, <Zn>.<T>[<imm>]

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; if tsz == '00000' then EndOfDecode(Decode_UNDEF); end; let lsb : integer{} = LowestSetBit(tsz); let esize : integer{} = 8 << lsb; let imm : bits(7) = imm2::tsz; let index : integer = UInt(imm[6:(lsb+1)]); 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 tsz:

tsz <T>
00000 RESERVED
xxxx1 B
xxx10 H
xx100 S
x1000 D
10000 Q
<Zn>

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

<imm>

Is the immediate index, in the range 0 to one less than the number of elements in 512 bits, encoded in "imm2:tsz".

Alias Conditions

AliasIs preferred when
MOV (SIMD&FP scalar, unpredicated)BitCount(imm2 :: tsz) == 1
MOV (SIMD&FP scalar, unpredicated)BitCount(imm2 :: tsz) > 1

Operation

CheckSVEEnabled(); let VL : integer{} = CurrentVL(); let elements : integer = VL DIV esize; let operand1 : bits(VL) = if index < elements then Z{VL}(n) else Zeros{VL}; var result : bits(VL); var element : bits(esize); if index >= elements then element = Zeros{esize}; else element = operand1[index*:esize]; end; result = Replicate{VL}(element); Z{VL}(d) = result;

Operational information

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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