SUBPS Subtract pointer, setting flags This instruction subtracts the 56-bit address held in the second source register from the 56-bit address held in the first source register, sign-extends the result to 64 bits, and writes the result to the destination register. It updates the condition flags based on the result of the subtraction. This instruction is used by the alias CMPP S == '1' && Rd == '11111' See below for details of when the alias is preferred. 1 0 1 1 1 0 1 0 1 1 0 0 0 0 0 0 0 SUBPS <Xd>, <Xn|SP>, <Xm|SP> if !IsFeatureImplemented(FEAT_MTE) then EndOfDecode(Decode_UNDEF); end; let d : integer{} = UInt(Rd); let n : integer{} = UInt(Rn); let m : integer{} = UInt(Rm); <Xd> Is the 64-bit name of the general-purpose destination register, encoded in the "Rd" field. <Xn|SP> Is the 64-bit name of the first source general-purpose register or stack pointer, encoded in the "Rn" field. <Xm|SP> Is the 64-bit name of the second general-purpose source register or stack pointer, encoded in the "Rm" field. Alias Conditions var operand1 : bits(64) = if n == 31 then SP{64}() else X{64}(n); var operand2 : bits(64) = if m == 31 then SP{64}() else X{64}(m); operand1 = SignExtend{64}(operand1[55:0]); operand2 = NOT(SignExtend{64}(operand2[55:0])); var result : bits(64); var nzcv : bits(4); (result, nzcv) = AddWithCarry{64}(operand1, operand2, '1'); X{64}(d) = result; PSTATE.[N,Z,C,V] = nzcv; 2026-03-26 20:27:25 2026-03_rel