> If you compile code on a machine with SSE or AVX and run it on an old Pentium, does it crash? Yes. Or it leaves them unused on the machine with avx. For sho

> If you compile code on a machine with SSE or AVX and run it on an old Pentium, does it crash? Yes. Or it leaves them unused on the machine with avx. For short runs of instructions, the overhead of fallback selection is larger than the overhead of using the least common denominator. For large functions, fallback selection is done by selecting specific functions after benchmarking.