LD1SB (scalar plus scalar)

Contiguous load signed bytes to vector (scalar index)

Contiguous load of signed bytes to elements of a vector register from the memory address generated by a 64-bit scalar base and scalar index which is added to the base address. After each element access the index value is incremented, but the index register is not updated. Inactive elements will not not cause a read from Device memory or signal a fault, and are set to zero in the destination vector.

It has encodings from 3 classes: 16-bit element , 32-bit element and 64-bit element

16-bit element

313029282726252423222120191817161514131211109876543210
10100101110Rm010PgRnZt
dtype<3:1>dtype<0>

LD1SB { <Zt>.H }, <Pg>/Z, [<Xn|SP>, <Xm>]

if !HaveSVE() && !HaveSME() 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 = 16; integer msize = 8; boolean unsigned = FALSE;

32-bit element

313029282726252423222120191817161514131211109876543210
10100101101Rm010PgRnZt
dtype<3:1>dtype<0>

LD1SB { <Zt>.S }, <Pg>/Z, [<Xn|SP>, <Xm>]

if !HaveSVE() && !HaveSME() 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 = 32; integer msize = 8; boolean unsigned = FALSE;

64-bit element

313029282726252423222120191817161514131211109876543210
10100101100Rm010PgRnZt
dtype<3:1>dtype<0>

LD1SB { <Zt>.D }, <Pg>/Z, [<Xn|SP>, <Xm>]

if !HaveSVE() && !HaveSME() 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 = 64; integer msize = 8; boolean unsigned = FALSE;

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(); integer elements = VL DIV esize; bits(64) base; bits(PL) mask = P[g]; bits(VL) result; bits(msize) data; bits(64) offset; constant integer mbytes = msize DIV 8; if HaveMTEExt() then SetTagCheckedInstruction(TRUE); 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]; offset = X[m]; for e = 0 to elements-1 if ElemP[mask, e, esize] == '1' then bits(64) addr = base + (UInt(offset) + e) * mbytes; data = Mem[addr, mbytes, AccType_NORMAL]; Elem[result, e, esize] = Extend(data, esize, unsigned); else Elem[result, e, esize] = Zeros(); Z[t] = result;


Internal version only: isa v33.11seprel, AdvSIMD v29.05, pseudocode v2021-09_rel, sve v2021-09_rc3d ; Build timestamp: 2021-10-06T11:41

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