Is it possible to modify the linux assembler in order to modify what fuctions do?

I was wondering if it were possible to modify the linux assembler in order to change the function of “-” to “+” and vice versa.
I was also wondering if this would affect the whole system making it collapse. I apologize if this question is not appropriate here. Please explain why if it is the case.

E.g:
2+2 = 0
2-2 = 4