The best approach is to generate custom code, with compile-time constant loop roll count and compile-time constant tail iteration count, like NN-512 (https://NN

The best approach is to generate custom code, with compile-time constant loop roll count and compile-time constant tail iteration count, like NN-512 (https://NN-512.com https://NN-512.com) does for almost every loop. Write your code generator in a developer-efficient, compiler-oriented language like Go. Use it to generate simple C99 that GCC can optimize to produce machine-efficient object code. This is how you get truly great object code from GCC.