LDAR Load-acquire register This instruction derives an address from a base register value, loads a 32-bit word or 64-bit doubleword from memory, and writes it to a register. The instruction also has memory ordering semantics as described in Load-Acquire, Store-Release. For information about addressing modes, see Load/Store addressing modes. For this instruction, if the destination is WZR/XZR, it is impossible for software to observe the presence of the acquire semantic other than its effect on the arrival at endpoints. If PSTATE.DIT is 1, the timing of this instruction is insensitive to the value of the data being loaded or stored. 1 x 0 0 1 0 0 0 1 1 0 (1) (1) (1) (1) (1) 1 (1) (1) (1) (1) (1) 0 LDAR <Wt>, [<Xn|SP>{, #0}] 1 LDAR <Xt>, [<Xn|SP>{, #0}] constant integer t = UInt(Rt); constant integer n = UInt(Rn); constant integer elsize = 8 << UInt(size); constant integer regsize = if elsize == 64 then 64 else 32; constant boolean tagchecked = n != 31; <Wt> Is the 32-bit name of the general-purpose register to be transferred, encoded in the "Rt" field. <Xn|SP> Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field. <Xt> Is the 64-bit name of the general-purpose register to be transferred, encoded in the "Rt" field. bits(64) address; constant integer dbytes = elsize DIV 8; constant AccessDescriptor accdesc = CreateAccDescAcqRel(MemOp_LOAD, tagchecked); if n == 31 then CheckSPAlignment(); address = SP[]; else address = X[n, 64]; constant bits(elsize) data = Mem[address, dbytes, accdesc]; X[t, regsize] = ZeroExtend(data, regsize);