LDNP (SIMD&FP)
Load pair of SIMD&FP registers, with non-temporal hint
This instruction loads a pair of SIMD&FP registers
from memory, issuing a hint to the memory
system that the access is non-temporal.
The address that is used for the load is calculated from a base register value
and an optional immediate offset.
For information about non-temporal pair instructions, see
Load/Store SIMD and Floating-point non-temporal pair.
Depending on the settings in the CPACR_EL1,
CPTR_EL2, and CPTR_EL3 registers,
and the current Security state and Exception level,
an attempt to execute the instruction might be trapped.
For information about the CONSTRAINED UNPREDICTABLE behavior of this instruction, see Architectural Constraints on UNPREDICTABLE behaviors, and particularly LDNP (SIMD&FP).
This instruction is a data-independent-time instruction as described in About PSTATE.DIT.
1
0
1
1
0
0
0
1
0
0
LDNP <St1>, <St2>, [<Xn|SP>{, #<imm>}]
0
1
LDNP <Dt1>, <Dt2>, [<Xn|SP>{, #<imm>}]
1
0
LDNP <Qt1>, <Qt2>, [<Xn|SP>{, #<imm>}]
// Empty.
<St1>
Is the 32-bit name of the first SIMD&FP register to be transferred, encoded in the "Rt" field.
<St2>
Is the 32-bit name of the second SIMD&FP register to be transferred, encoded in the "Rt2" field.
<Xn|SP>
Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field.
<imm>
For the "32-bit" variant: is the optional signed immediate byte offset, a multiple of 4 in the range -256 to 252, defaulting to 0 and encoded in the "imm7" field as <imm>/4.
<imm>
For the "64-bit" variant: is the optional signed immediate byte offset, a multiple of 8 in the range -512 to 504, defaulting to 0 and encoded in the "imm7" field as <imm>/8.
<imm>
For the "128-bit" variant: is the optional signed immediate byte offset, a multiple of 16 in the range -1024 to 1008, defaulting to 0 and encoded in the "imm7" field as <imm>/16.
<Dt1>
Is the 64-bit name of the first SIMD&FP register to be transferred, encoded in the "Rt" field.
<Dt2>
Is the 64-bit name of the second SIMD&FP register to be transferred, encoded in the "Rt2" field.
<Qt1>
Is the 128-bit name of the first SIMD&FP register to be transferred, encoded in the "Rt" field.
<Qt2>
Is the 128-bit name of the second SIMD&FP register to be transferred, encoded in the "Rt2" field.
if !IsFeatureImplemented(FEAT_FP) then EndOfDecode(Decode_UNDEF); end;
let t : integer{} = UInt(Rt);
let t2 : integer{} = UInt(Rt2);
let n : integer{} = UInt(Rn);
let nontemporal : boolean = TRUE;
let scale : integer{} = 2 + (UInt(opc) as integer{0..2});
let datasize : integer{} = 8 << scale;
let offset : bits(64) = LSL(SignExtend{64}(imm7), scale);
let tagchecked : boolean = n != 31;
var rt_unknown : boolean = FALSE;
if t == t2 then
let c : Constraint = ConstrainUnpredictable(Unpredictable_LDPOVERLAP);
assert c IN {Constraint_UNKNOWN, Constraint_UNDEF, Constraint_NOP};
case c of
when Constraint_UNKNOWN => rt_unknown = TRUE; // Result is UNKNOWN
when Constraint_UNDEF => EndOfDecode(Decode_UNDEF);
when Constraint_NOP => EndOfDecode(Decode_NOP);
end;
end;
AArch64_CheckFPEnabled();
var address : bits(64);
let dbytes : integer{} = datasize DIV 8;
let privileged : boolean = PSTATE.EL != EL0;
let ispair : boolean = TRUE;
let accdesc : AccessDescriptor = CreateAccDescASIMD(MemOp_LOAD, nontemporal, tagchecked,
privileged, ispair);
if n == 31 then
CheckSPAlignment();
address = SP{64}();
else
address = X{64}(n);
end;
address = AddressAdd(address, offset, accdesc);
let data : bits(2*datasize) = Mem{2*datasize}(address, accdesc);
if rt_unknown then
V{datasize}(t) = ARBITRARY : bits(datasize);
elsif BigEndian(accdesc.acctype) then
V{datasize}(t2) = data[(datasize-1):0];
V{datasize}(t) = data[(2*datasize-1):datasize];
else
V{datasize}(t) = data[(datasize-1):0];
V{datasize}(t2) = data[(2*datasize-1):datasize];
end;
2026-03-12 12:23:09
2025-09_rel_asl1