Conditionally extract last element to vector register
From the second source vector register extract the last active element, and then replicate that element to destructively fill the destination and first source vector.
If there are no active elements then leave the destination and source vector unmodified.
| 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 | size | 1 | 0 | 1 | 0 | 0 | 1 | 1 | 0 | 0 | Pg | Zm | Zdn | |||||||||||
| B | |||||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer esize = 8 << UInt(size); constant integer g = UInt(Pg); constant integer dn = UInt(Zdn); constant integer m = UInt(Zm); constant boolean isBefore = TRUE;
| <Zdn> |
Is the name of the first source and destination scalable vector register, encoded in the "Zdn" 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. |
| <Zm> |
Is the name of the second source scalable vector register, encoded in the "Zm" field. |
CheckSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant integer elements = VL DIV esize; constant bits(PL) mask = P[g, PL]; constant bits(VL) operand1 = Z[dn, VL]; constant bits(VL) operand2 = Z[m, VL]; bits(VL) result; integer last = LastActiveElement(mask, esize); if last < 0 then result = operand1; else if !isBefore then last = last + 1; if last >= elements then last = 0; for e = 0 to elements-1 Elem[result, e, esize] = Elem[operand2, last, esize]; Z[dn, VL] = result;
This instruction might be immediately preceded in program order by a MOVPRFX instruction. The MOVPRFX must conform to all of the following requirements, otherwise the behavior of the MOVPRFX and this instruction is constrained unpredictable:
Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45
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