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STR (vector)

Store vector register

This instruction stores a vector register to a memory address generated by a 64-bit scalar base, plus an immediate offset in the range -256 to 255 that is multiplied by the current vector register size in bytes. This instruction is unpredicated.

The store is performed as contiguous byte accesses, with no endian conversion and no guarantee of single-copy atomicity larger than a byte. However, if alignment is checked, then the base register must be aligned to 16 bytes.

SVE class

(FEAT_SVE || FEAT_SME)

313029282726252423222120191817161514131211109876543210
1110010110imm9h010imm9lRnZt

Encoding

STR <Zt>, [<Xn|SP>{, #<imm>, MUL VL}]

Decode

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); constant integer t = UInt(Zt); constant integer n = UInt(Rn); constant integer imm = SInt(imm9h:imm9l);

Assembler Symbols

<Zt>

Is the name of the scalable vector register to be transferred, encoded in the "Zt" 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 vector offset, in the range -256 to 255, defaulting to 0, encoded in the "imm9h:imm9l" fields.

Operation

CheckSVEEnabled(); constant integer VL = CurrentVL; constant integer elements = VL DIV 8; bits(VL) src; bits(64) base; constant integer offset = imm * elements; constant boolean contiguous = TRUE; constant boolean nontemporal = FALSE; constant boolean predicated = FALSE; constant boolean tagchecked = n != 31; constant AccessDescriptor accdesc = CreateAccDescSVE(MemOp_STORE, nontemporal, contiguous, predicated, tagchecked); if n == 31 then CheckSPAlignment(); base = SP[64]; else base = X[n, 64]; src = Z[t, VL]; bits(64) addr = AddressAdd(base, offset, accdesc); constant boolean aligned = IsAligned(addr, 16); if !aligned && AlignmentEnforced() then constant FaultRecord fault = AlignmentFault(accdesc, addr); AArch64.Abort(fault); for e = 0 to elements-1 AArch64.MemSingle[addr, 1, accdesc, aligned] = Elem[src, e, 8]; addr = AddressIncrement(addr, 1, accdesc);

Operational information

This instruction is a data-independent-time instruction as described in About PSTATE.DIT.


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