Well, it'd be more helpful if you told us which assembly language so we could look at the instruction set. If it's say 68HC11, I'm not aware of any instruction that could let you implement this.
How many registers do you have? 8 Multipurpose registers? Some architectures only have 4 registers. It's not likely to be very many. There are also different kinds of registers such as accumulators and index registers.
If you're programming in x68 assembly I don't think theres a way to loop through registers and the closest that you get to it is the pop all registers and push all registers into a stack. But that's not going to accomplish what you are going for here.