loop through register

Hi to all,
how can I loop through each rgister from r0 to r7?
I have some data in the registers r0:r7 and i want to compare them with a constant; i need to put 8 line of sub and cmp or is there any solution with branches in order make the solution more clever like a "branch for registers".
I googled but the only i can find is how to manage this king of loop when i have data in memory and not in registers.

The pseudocode i want to achive is the one below

for 0 to 7
  cmp r(i), #3
end

Any suggestion?
Thanks for any advice