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LD1D (vector plus immediate)

Gather load doublewords to vector (immediate index)

Gather load of doublewords to active elements of a vector register from memory addresses generated by a vector base plus immediate index. The index is a multiple of 8 in the range 0 to 248. Inactive elements will not cause a read from Device memory or signal faults, and are set to zero in the destination vector.

This instruction is illegal when executed in Streaming SVE mode, unless FEAT_SME_FA64 is implemented and enabled.

SVE

(FEAT_SVE)

313029282726252423222120191817161514131211109876543210
11000101101imm5110PgZnZt
mszUff

Encoding

LD1D { <Zt>.D }, <Pg>/Z, [<Zn>.D{, #<imm>}]

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) then EndOfDecode(Decode_UNDEF); constant integer t = UInt(Zt); constant integer n = UInt(Zn); constant integer g = UInt(Pg); constant integer esize = 64; constant integer msize = 64; constant boolean unsigned = TRUE; constant integer offset = UInt(imm5);

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.

<Zn>

Is the name of the base scalable vector register, encoded in the "Zn" field.

<imm>

Is the optional unsigned immediate byte offset, a multiple of 8 in the range 0 to 248, defaulting to 0, encoded in the "imm5" field.

Operation

CheckNonStreamingSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant integer elements = VL DIV esize; constant bits(PL) mask = P[g, PL]; bits(VL) base; bits(VL) result; bits(msize) data; constant integer mbytes = msize DIV 8; constant boolean contiguous = FALSE; constant boolean nontemporal = FALSE; constant boolean tagchecked = TRUE; constant AccessDescriptor accdesc = CreateAccDescSVE(MemOp_LOAD, nontemporal, contiguous, tagchecked); if AnyActiveElement(mask, esize) then base = Z[n, VL]; for e = 0 to elements-1 if ActivePredicateElement(mask, e, esize) then constant bits(64) baddr = ZeroExtend(Elem[base, e, esize], 64); constant bits(64) addr = AddressAdd(baddr, offset * mbytes, accdesc); data = Mem[addr, mbytes, accdesc]; Elem[result, e, esize] = Extend(data, esize, unsigned); else Elem[result, e, esize] = Zeros(esize); Z[t, VL] = result;