STNT1D (scalar plus scalar, single register)

Contiguous store non-temporal doublewords from vector (scalar index)

This instruction performs a contiguous non-temporal store of doublewords from elements of a vector register to the memory address generated by a 64-bit scalar base and scalar index that is multiplied by 8 and added to the base address. After each element access the index value is incremented, but the index register is not updated. Inactive elements are not written to memory.

A non-temporal store is a hint to the system that this data is unlikely to be referenced again soon.

SVE
(FEAT_SVE || FEAT_SME)

313029282726252423222120191817161514131211109876543210
11100101100!= 11111011PgRnZt
mszRm

Encoding

STNT1D { <Zt>.D }, <Pg>, [<Xn|SP>, <Xm>, LSL #3]

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let t : integer = UInt(Zt); let n : integer = UInt(Rn); let m : integer = UInt(Rm); let g : integer = UInt(Pg); let esize : integer{} = 64;

Assembler Symbols

<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.

<Xm>

Is the 64-bit name of the general-purpose offset register, encoded in the "Rm" field.

Operation

CheckSVEEnabled(); let VL : integer{} = CurrentVL(); let PL : integer{} = VL DIV 8; let elements : integer = VL DIV esize; var base : bits(64); var offset : bits(64); var addr : bits(64); var src : bits(VL); let mask : bits(PL) = P{}(g); let mbytes : integer{} = esize DIV 8; let contiguous : boolean = TRUE; let nontemporal : boolean = TRUE; let predicated : boolean = TRUE; let tagchecked : boolean = TRUE; let accdesc : AccessDescriptor = CreateAccDescSVE(MemOp_STORE, 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; src = Z{VL}(t); end; base = if n == 31 then SP{64}() else X{64}(n); offset = X{64}(m); addr = AddressAdd(base, UInt(offset) * mbytes, accdesc); for e = 0 to elements-1 do if ActivePredicateElement{PL}(mask, e, esize) then Mem{esize}(addr, accdesc) = src[e*:esize]; end; addr = AddressIncrement(addr, mbytes, accdesc); end;

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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