Function hash_bytes

pub(crate) fn hash_bytes(bytes: &[u8]) -> u64

A wyhash-inspired non-collision-resistant hash for strings/slices designed by Orson Peters, with a focus on small strings and small codesize.

The 64-bit version of this hash passes the SMHasher3 test suite on the full 64-bit output, that is, f(hash_bytes(b) ^ f(seed)) for some good avalanching permutation f() passed all tests with zero failures. When using the 32-bit version of multiply_mix this hash has a few non-catastrophic failures where there are a handful more collisions than an optimal hash would give.

We don’t bother avalanching here as we’ll feed this hash into a multiplication after which we take the high bits, which avalanches for us.