simdutf8 VS encoding_rs

That's not enough to make it interesting. There's already a porting of it in rust (https://github.com/rusticstuff/simdutf8), and inclusion in the stdlib has already been discussed: the problem is that you can't use simd in all supported targets and conditional compilation/detection is also very tricky.

No, libcore uses simple branching code at the moment, see https://github.com/rust-lang/rust/issues/68455. The issue is still actively being worked on. Note, it's not a simple drop in, and there seem to be even faster algorithms. For now there is https://github.com/rusticstuff/simdutf8.

I will work on simdutf8, either

Now I have to benchmark again, it might be negligable. See also the discussion for this pull request.

Check the benchmarks section (https://github.com/rusticstuff/simdutf8#Benchmarks), second table. simdutf8 is up to 28 % faster on my Comet Lake CPU. However with pure ASCII clang does something magical with simdjson and it beats my implementation by a lot. GCC-compiled simdjson is slower all around except for a few outliers with short byte sequences.

The algorithm is the one from simdjson, the main difference is that it uses an extra step in the beginning to align reads to the SIMD block size.

Author of ripgrep here.

Maybe, umm, don't depend on auto-detection tools as the ultimeate source of whether something is appropriately licensed or not? encoding_rs is clearly licensed, otherwise I wouldn't have used it in ripgrep: https://github.com/hsivonen/encoding_rs

Take it up with the auto-detection tools. Or at least do your due diligence before claiming ripgrep is using "unlicensed" code.

You might also want to include tests, https://github.com/hsivonen/encoding_rs/tree/master/src/test_data could be used as a reference.

That's not the only use of SIMD in the crate (e.g. see https://github.com/hsivonen/encoding_rs/blob/e98a2096ab09c92...), but I haven't looked into exactly where/how it's used further.