Contiguous load and replicate eight halfwords (immediate index)
This instruction loads eight contiguous halfwords to elements of a short, 128-bit (quadword) vector from the memory address generated by a 64-bit scalar base address and immediate index that is a multiple of 16 in the range -128 to +112 added to the base address.
Inactive elements will not cause a read from Device memory or signal a fault, and are set to zero. The resulting short vector is then replicated to fill the long destination vector. Only the first eight predicate elements are used and higher numbered predicate elements are ignored.
| 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 |
| 1 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | imm4 | 0 | 0 | 1 | Pg | Rn | Zt | |||||||||||||
| msz | ssz | ||||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let t : integer = UInt(Zt); let n : integer = UInt(Rn); let g : integer = UInt(Pg); let esize : integer{} = 16; let offset : integer = SInt(imm4);
| <Zt> |
Is the name of the scalable vector register to be transferred, encoded in the "Zt" field. |
| <Pg> |
Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field. |
| <Xn|SP> |
Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field. |
| <imm> |
Is the optional signed immediate byte offset, a multiple of 16 in the range -128 to 112, defaulting to 0, encoded in the "imm4" field. |
CheckSVEEnabled(); let VL : integer{} = CurrentVL(); let PL : integer{} = VL DIV 8; let elements : integer = 128 DIV esize; var base : bits(64); let mask : bits(PL) = P{}(g); // low 16 bits only var addr : bits(64); var result : bits(128); let mbytes : integer{} = esize DIV 8; let contiguous : boolean = TRUE; let nontemporal : boolean = FALSE; let predicated : boolean = TRUE; let tagchecked : boolean = n != 31; let accdesc : AccessDescriptor = CreateAccDescSVE(MemOp_LOAD, nontemporal, contiguous, predicated, tagchecked); if !AnyActiveElement{PL}(mask, esize) then if n == 31 && ConstrainUnpredictableBool(Unpredictable_CHECKSPNONEACTIVE) then CheckSPAlignment(); end; else if n == 31 then CheckSPAlignment(); end; end; base = if n == 31 then SP{64}() else X{64}(n); addr = AddressAdd(base, offset * 16, accdesc); for e = 0 to elements-1 do if ActivePredicateElement{PL}(mask, e, esize) then result[e*:esize] = Mem{esize}(addr, accdesc); else result[e*:esize] = Zeros{esize}; end; addr = AddressIncrement(addr, mbytes, accdesc); end; Z{VL}(t) = Replicate{VL}(result);
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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