ni...@lysator.liu.se (Niels Möller) writes: And to make the loop work, it needs some condition to decrement N and maintain non-zero high limbs (if both up[N-1] and vp[N-1] are zero, comparison is no good). So that would be something like
Since N is my proposal is a constant, it is considered bad practice to decrement it. Instead i expect deflection to a loop handling N-1. Besides, I am not sure you got the decrementation criteria exactly right. ;-) Back when the current gcd code was written, I think it won against the accelerated binary gcd also for small sizes, and that's why we didn't introduce any lehmer-vs-binary threshold. I believe we will be able to beat the old "accelerated binary" code and the present code with a branch-reduced approach. Reducing the branches should be done next, but it will take some work to reduce it enough for a significant speedup. At least that's my understanding. -- Torbjörn Please encrypt, key id 0xC8601622 _______________________________________________ gmp-devel mailing list gmp-devel@gmplib.org https://gmplib.org/mailman/listinfo/gmp-devel
