For anyone curious: the performance difference between Clang and GCC on the example C solution for verbal arithmetic comes down to Clang's auto-vectorisation (deducing SIMD) whilst GCC here sticks with scalar, which is why the counter brings Clang closer in line to GCC (https://godbolt.org/z/xfdxGvMYP), and it's actually a pretty nice example of auto-vectorisation (and its limitations) in action, which is a fun tangent from this article (given its relevance to high-performance SMT/SAT solving for CSP)