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LDR (predicate)

Load predicate register.

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

The load is performed as a stream of bytes containing 8 consecutive predicate bits in ascending element order, without any endian conversion.

313029282726252423222120191817161514131211109876543210
1000010110imm9h000imm9lRn0Pt

SVE

LDR <Pt>, [<Xn|SP>{, #<imm>, MUL VL}]

if !HaveSVE() then UNDEFINED;
integer t = UInt(Pt);
integer n = UInt(Rn);
integer imm = SInt(imm9h:imm9l);

Assembler Symbols

<Pt>

Is the name of the destination scalable predicate register, encoded in the "Pt" 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();
integer elements = PL DIV 8;
bits(64) base;
integer offset = imm * elements;
bits(PL) result;

if n == 31 then
    CheckSPAlignment();
    if HaveMTEExt() then SetTagCheckedInstruction(FALSE);
    base = SP[];
else
    if HaveMTEExt() then SetTagCheckedInstruction(TRUE);
    base = X[n];

boolean aligned = AArch64.CheckAlignment(base + offset, 2, AccType_NORMAL, FALSE);
for e = 0 to elements-1
    Elem[result, e, 8] = AArch64.MemSingle[base + offset, 1, AccType_NORMAL, aligned];
    offset = offset + 1;

P[t] = result;