Conditionally extract element after last to vector register
From the second source vector register extract the element after the last active element, or if the last active element is the final element extract element zero, 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 | 0 | 1 | 0 | 0 | Pg | Zm | Zdn | |||||||||||
| B | |||||||||||||||||||||||||||||||
if !HaveSVE() && !HaveSME() then UNDEFINED; constant integer esize = 8 << UInt(size); integer g = UInt(Pg); integer dn = UInt(Zdn); integer m = UInt(Zm); boolean isBefore = FALSE;
| <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; bits(PL) mask = P[g, PL]; bits(VL) operand1 = Z[dn, VL]; 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 instruction must conform to all of the following requirements, otherwise the behavior of the MOVPRFX and this instruction is unpredictable:
Internal version only: aarchmrs v2023-12_rel, pseudocode v2023-12_rel, sve v2023-12_rel ; Build timestamp: 2023-12-15T16:46
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