STNT1B (scalar plus scalar, single register)

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

This instruction performs a contiguous non-temporal store of bytes from elements of a vector register to the memory address generated by a 64-bit scalar base and scalar index that is 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
11100100000!= 11111011PgRnZt
mszRm

Encoding

STNT1B { <Zt>.B }, <Pg>, [<Xn|SP>, <Xm>]

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{} = 8;

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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