Can I compare (CMP) immediate values in Assembly?

Question

I tried to assemble the following instruction:

cmp 5, 6

But I got the following error:

invalid combination of opcode and operands

So I edited the previous instruction into this:

cmp DWORD 5, DWORD 6

But still I got the same error, so is comparing immediate values illegal in Assembly?

Answer 1

In x86 assembly according to your assembler(eg tasm, masm or nasm ) you cannot compare immediates or variables with each other. You have to put one or both of them in a register. like this:

mov ax, 5
cmp ax, 6

or

mov ax, 5
mov bx, 6
cmp ax, bx

There you go.

Answer 2

No, this is not possible. The x86 instruction set doesn't have opcodes for such operations on immediate values and assembly compilers aren't here to interpret them.

Answer 3

您可以将单个立即数与寄存器或内存中的值进行比较。