Something like #pragma simd may actually be worse than letting GCC do its thing. It may not use FMA, just AVX, for instance. You may also want (a subset of) -f

Something like #pragma simd may actually be worse than letting GCC do its thing. It may not use FMA, just AVX, for instance. You may also want (a subset of) -ffast-math for NEON, reductions, etc., if your code is OK with it.