Example of instructions, doesn't use functional unit at all?

Hello to all,

I need a small help with the processor instructions. Can anybody provide me an example where during execution, the functional unit must not be used or it must be deactivated? 

All data-processing and data-transfer instruction need the functional unit. Initially, I thought the NOP instruction can be one of the examples, but while going through the documentations, I got to know that NOP instruction is nothing but the MOV R8,R8. 

I really want to measure the effect of functional unit activation and deactivation. So, is there any instruction example or any measurement technique, which will be helpful in our case?

I am working on ARM Cortex-M4.

Thanking you in advance,

Warm Regards,

Himanshu