Add BLAKE3 source code to third_party

[tylerwilliams]

Add BLAKE3 source code to third_party

This PR adds the BLAKE3 C and asm sources to third_party, and includes a BUILD
file to build them.

This is a partial commit for #18658.

[coeuvre]

I'm not familiar with BLAKE3's source code. Are these assembly code optional so that when targeting other platforms the code can still be compiled but is just slower? I guess the copts below answers my question but just want to double check.

cc @meteorcloudy for potential caring when targeting other platforms.

[tylerwilliams]

Yes, you got it. The blake3_portable.c implementation is a safe fallback for architectures which do not support the vectorized ASM implementations.

[meteorcloudy]

I strongly recommend to introduce new external dependencies as external repositories instead of checking in the third_party directory.

[coeuvre]

@meteorcloudy Do we have docs/examples on how to do that?

[meteorcloudy]

Yes, you can add a dependency in https://github.com/bazelbuild/bazel/blob/master/distdir_deps.bzl#L120 and put a dist_http_archive in the WORKSPACE file:

bazel/WORKSPACE

Line 326 in e382abf

dist_http_archive(

Also, it'll be nice this could be submit to the BCR so that it's also available in Bzlmod.

[coeuvre]

@tylerwilliams Mind looking at what Yun suggested?

[tylerwilliams]

@tylerwilliams Mind looking at what Yun suggested?

Done. I will send a separate CL to BCR to add this over there as well (but don't want to block the rest of the changes).

[tylerwilliams]

Yes, you can add a dependency in https://github.com/bazelbuild/bazel/blob/master/distdir_deps.bzl#L120 and put a dist_http_archive in the WORKSPACE file:

bazel/WORKSPACE

Line 326 in e382abf

dist_http_archive(

Also, it'll be nice this could be submit to the BCR so that it's also available in Bzlmod.

@meteorcloudy I sent that CL here: bazelbuild/bazel-central-registry#698

[meteorcloudy]

@sgowroji You can import the third_party change first, then the non-third_party change. I think the import scripts will work without having to split this PR.

[sgowroji]

Hi @tylerwilliams, Could you please squash the commits in to one, So that i can initiate the import. Thanks!

[tylerwilliams]

Hi @tylerwilliams, Could you please squash the commits in to one, So that i can initiate the import. Thanks!

@sgowroji Sure, done!

[sgowroji]

Third party changes merged at 0ff4f6d

[iancha1992]

The changes in this PR have been included in Bazel 6.4.0 RC1. Please test out the release candidate and report any issues as soon as possible. If you're using Bazelisk, you can point to the latest RC by setting USE_BAZEL_VERSION=last_rc.
Thanks!