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LD1ROB (scalar plus scalar)

Contiguous load and replicate thirty-two bytes (scalar index).

Load thirty-two contiguous bytes to elements of a 256-bit (octaword) vector from the memory address generated by a 64-bit scalar base address and scalar index which is added to the base address.

Inactive elements will not read Device memory or signal a fault, and are set to zero.

The resulting 256-bit vector is then replicated to fill the destination vector. The instruction requires that the current vector length is at least 256 bits, and if the current vector length is not an integer multiple of 256 bits then the trailing bits in the destination vector are set to zero.

Only the first thirty-two predicate elements are used and higher numbered predicate elements are ignored.

ID_AA64ZFR0_EL1.F64MM indicates whether this instruction is implemented.



LD1ROB { <Zt>.B }, <Pg>/Z, [<Xn|SP>, <Xm>]

if !HaveSVEFP64MatMulExt() then UNDEFINED;
if Rm == '11111' then UNDEFINED;
integer t = UInt(Zt);
integer n = UInt(Rn);
integer m = UInt(Rm);
integer g = UInt(Pg);
integer esize = 8;

Assembler Symbols


Is the name of the scalable vector register to be transferred, encoded in the "Zt" field.


Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field.


Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field.


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


if VL < 256 then UNDEFINED;
integer elements = 256 DIV esize;
bits(64) base;
bits(64) addr;
bits(PL) mask = P[g]; // low bits only
bits(64) offset;
bits(256) result;
constant integer mbytes = esize DIV 8;

if HaveMTEExt() then SetTagCheckedInstruction(TRUE);

if n == 31 then
    if LastActiveElement(mask, esize) >= 0 || 
          ConstrainUnpredictableBool(Unpredictable_CHECKSPNONEACTIVE) then 
    base = SP[];
    base = X[n];

offset = X[m];

addr = base + UInt(offset) * mbytes;
for e = 0 to elements-1
    if ElemP[mask, e, esize] == '1' then
        Elem[result, e, esize] = Mem[addr, mbytes, AccType_NORMAL];
        Elem[result, e, esize] = Zeros();
    addr = addr + mbytes;

Z[t] = ZeroExtend(Replicate(result, VL DIV 256), VL);