DUP (indexed)

Broadcast indexed element to vector (unpredicated)

Unconditionally broadcast 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.

Encoding: SVE

Variants: FEAT_SVE || FEAT_SME (FEAT_SVE || FEAT_SME)

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	0	0	0	0	1	0	1			1						0	0	1	0	0	0
								imm2			tsz											Zn					Zd

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

Decoding algorithm

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then
    EndOfDecode(Decode_UNDEF);
if tsz == '00000' then EndOfDecode(Decode_UNDEF);
constant integer lsb = LowestSetBit(tsz);
constant integer esize = 8 << lsb;
constant bits(7) imm = imm2:tsz;
constant integer index = UInt(imm<6:(lsb+1)>);
constant integer n = UInt(Zn);
constant integer d = UInt(Zd);

Operation

CheckSVEEnabled();
constant integer VL = CurrentVL;
constant integer elements = VL DIV esize;
constant bits(VL) operand1 = if index < elements then Z[n, VL] else Zeros(VL);
bits(VL) result;
bits(esize) element;

if index >= elements then
    element = Zeros(esize);
else
    element = Elem[operand1, index, esize];
result = Replicate(element, VL DIV esize);

Z[d, VL] = result;

Explanations

<Zd>: Is the name of the destination scalable vector register, encoded in the "Zd" field.
<T>: <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".

Operational Notes

If PSTATE.DIT is 1:

• The execution time of this instruction is independent of:
  • The values of the data supplied in any of its registers.
  • The values of the NZCV flags.
• The response of this instruction to asynchronous exceptions does not vary based on:
  • The values of the data supplied in any of its registers.
  • The values of the NZCV flags.