!320 (merged) has the side effect of breaking detection of SVE vectorization support and enablement of SVE in the compiler. My patch should properly fix the underlying problem.
py-cpuinfo is supported on ARM64 and can be used to detect Neon and SVE. However, there was indeed a bug here -- Neon is identified as asimd in /proc/cpuinfo, so we should check for asimd instead of neon.
While -march=native was not supported by Clang before 15, -mcpu=native is supported by GCC 6+ and Clang 7+. Let's use that instead of not adding a flag at all -- otherwise SVE support is not enabled in the compiler even if the hardware supports it.