The repository currently has no license, which means that people can't use the code, or legal uncertainty, depending on the jurisdiction. Please choose a license and make it explicit whether you want people to use the code or not.
In benchmark, AVX512VBMI (despacing) seems to fail. It returns -1 when it should return the length. I will switch it over to a NO_CHECK in the benchmarking, because I don't care about it at this time... but this should probably get looked at.