Go's strings.Index/bytes.Index also often use the "find first byte" approach; now on amd64 it's a fancy vector instruction. If it finds the first byte too many

Go's strings.Index/bytes.Index also often use the "find first byte" approach; now on amd64 it's a fancy vector instruction. If it finds the first byte too many times without a full match, it falls back to a Rabin-Karp match using a rolling multiplicative hash. The strings.Index code is at https://golang.org/src/strings/strings.go?s=25956:25988#L1018 https://golang.org/src/strings/strings.go?s=25956:25988#L101... and the internal bytealg package with all the CPU intrinsics is at https://golang.org/src/internal/bytealg/ https://golang.org/src/internal/bytealg/ with index_amd64.{go,s} as the relevant files for x64. Battle-tested implementations of fundamental things like string searches, sorts, hashtables, allocators, graphics primitives, etc. are often interesting 'cause you find out a lot about what you need (and/or don't need) to work well in practice as well as protect from exploding worst-case scenarios.