LD1RQB (scalar plus immediate)

Contiguous load and replicate sixteen bytes (immediate index)

Load sixteen contiguous bytes 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 sixteen predicate elements are used and higher numbered predicate elements are ignored.

313029282726252423222120191817161514131211109876543210
101001000000imm4001PgRnZt
msz<1>msz<0>ssz

LD1RQB { <Zt>.B }, <Pg>/Z, [<Xn|SP>{, #<imm>}]

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED; constant integer t = UInt(Zt); constant integer n = UInt(Rn); constant integer g = UInt(Pg); constant integer esize = 8; constant integer offset = SInt(imm4);

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.

<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.

Operation

CheckSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant integer elements = 128 DIV esize; bits(64) base; constant bits(PL) mask = P[g, PL]; // low 16 bits only bits(64) addr; bits(128) result; constant integer mbytes = esize DIV 8; constant boolean contiguous = TRUE; constant boolean nontemporal = FALSE; constant boolean tagchecked = n != 31; constant AccessDescriptor accdesc = CreateAccDescSVE(MemOp_LOAD, nontemporal, contiguous, tagchecked); if !AnyActiveElement(mask, esize) then if n == 31 && ConstrainUnpredictableBool(Unpredictable_CHECKSPNONEACTIVE) then CheckSPAlignment(); else if n == 31 then CheckSPAlignment(); base = if n == 31 then SP[] else X[n, 64]; addr = AddressAdd(base, offset * 16, accdesc); for e = 0 to elements-1 if ActivePredicateElement(mask, e, esize) then Elem[result, e, esize] = Mem[addr, mbytes, accdesc]; else Elem[result, e, esize] = Zeros(esize); addr = AddressIncrement(addr, mbytes, accdesc); Z[t, VL] = Replicate(result, VL DIV 128);

Operational information

If FEAT_SVE2 is implemented or FEAT_SME is implemented, then if PSTATE.DIT is 1, the timing of this instruction is insensitive to the value of the data being loaded or stored when its governing predicate register contains the same value for each execution.


Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45

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