I've sent you a small donation for your hard work, but...

Do pools accept any hashes generated with your kernel? Really? For instance, the 'local' optimization was declared invalid (it messes up the calculation, so the thread got locked by the moderator), etc.

EDIT - As to why exit early on the if()-s... well, if you found a solution already, why do you need a second solution? Doing branches on the GPU is very expensive (threads may diverge, etc.), so two branches may and most likely will end up being worse than one. May I suggest if(min(x,y)==0) { output x; }? Assuming min can be done without branching, this is one branch if you don't have a solution in either x or y (if min is not 1 instruction, find another function to replace the min...), then try both x and (x+1) on the CPU side to figure out which one of these is the real solution.