CMN (immediate) Compare Negative (immediate) Compare Negative (immediate) adds a register value and an immediate value. It updates the condition flags based on the result, and discards the result. For more information about the CONSTRAINED UNPREDICTABLE behavior, see Architectural Constraints on UNPREDICTABLE behaviors. This instruction is a data-independent-time instruction as described in About the DIT bit. It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) . != 1111 0 0 1 1 0 1 1 1 (0) (0) (0) (0) CMN{<c>}{<q>} <Rn>, #<const> let n : integer = UInt(Rn); let imm32 : bits(32) = A32ExpandImm(imm12); 1 1 1 1 0 0 1 0 0 0 1 0 1 1 1 1 CMN{<c>}{<q>} <Rn>, #<const> let n : integer = UInt(Rn); let imm32 : bits(32) = T32ExpandImm(i::imm3::imm8); if n == 15 then UnpredictableProcedure(); end; <c> See Standard assembler syntax fields. <q> See Standard assembler syntax fields. <Rn> For the "A1" variant: is the general-purpose source register, encoded in the "Rn" field. The PC can be used, but this is deprecated. <Rn> For the "T1" variant: is the general-purpose source register, encoded in the "Rn" field. <const> For the "A1" variant: an immediate value. See Modified immediate constants in A32 instructions for the range of values. <const> For the "T1" variant: an immediate value. See Modified immediate constants in T32 instructions for the range of values. if ConditionPassed() then EncodingSpecificOperations(); let (result, nzcv) : (bits(32), bits(4)) = AddWithCarry{32}(R(n), imm32, '0'); PSTATE.[N,Z,C,V] = nzcv; end; 2026-03-12 12:23:09 2025-09_rel_asl1