I've reviewed the three header files added toPC and they seem generic. It's a shame they aren't part of the sources, but figured it's easier/safer to just copy them into our source tree so that the cpython-source-deps repo is a straight import.

🤖 New build scheduled with the buildbot fleet by@zooba for commit08eecb1 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F131438%2Fmerge

If you want to schedule another build, you need to add the🔨 test-with-buildbots label again.

The two failing buildbots appear unrelated, and everything else passed. All I changed in the last commit was docs, so I'm not going to rerun the buildbots unless someone thinks it's necessary or worthwhile.

I'm kicking off a pyperformance benchmarking run with this -- we have a non-zero usage of zlib in that suite.

The results for this on pyperformance are basically within the noise / no change. Not all that surprising, given that there are no benchmarksspecifically aimed at zlib.https://github.com/faster-cpython/benchmarking-public/tree/main/results/bm-20250319-3.14.0a6+-548daa7

This has broken the tailcall builds on Windows:https://github.com/python/cpython/actions/runs/13967899073/job/39102464260

D:\a\cpython\cpython\externals\\zlib-ng-2.2.4\\functable.c(79,26): error : use of undeclared identifier 'slide_hash_sse2'; did you mean 'slide_hash_c'? [D:\a\cpython\cpython\PCbuild\zlib-ng.vcxproj]D:\a\cpython\cpython\externals\\zlib-ng-2.2.4\\functable.c(123,26): error : use of undeclared identifier 'slide_hash_avx2'; did you mean 'slide_hash_c'? [D:\a\cpython\cpython\PCbuild\zlib-ng.vcxproj]

Probably needs some fixed preprocessor checks (hopefully only in what's in thePC directory) to better handle the intrinsics being present/absent.

Though I notice that build warnsNOTE: Visual Studio not detected. LLVM does not provide a C/C++ standard library and may be unable to locate MSVC headers., which might also be relevant.

I think, this is because here
https://github.com/zlib-ng/zlib-ng/blob/860e4cff7917d93f54f5d7f0bc1d0e8b1a3cb988/fallback_builtins.h#L4-L25
in line 4__clang__ gets excluded and hence#define HAVE_BUILTIN_CTZ is not set (but in the MSVC case it is).

Then, in
https://github.com/zlib-ng/zlib-ng/blob/860e4cff7917d93f54f5d7f0bc1d0e8b1a3cb988/arch/x86/x86_functions.h#L13-L20
we dont get the prototype forslide_hash_sse2 in line 17, hence the error.

Sorry, I cannot get the permalinks to work here the usual way I am doing it :(

Though I notice that build warnsNOTE: Visual Studio not detected. LLVM does not provide a C/C++ standard library and may be unable to locate MSVC headers., which might also be relevant.

FWIW, when building with the bundled clang-cl of VS I do not have these warnings, but get the same error.

Most likely zlib-ng would generate different versions of the header files I checked into thePC directory for Clang. Figuring out what differences belong in there and detecting it dynamically rather than using CMake is the way forward.

This should get a new issue (because clang-cl isn't a supported configuration, so we don't have to revert this change until it's working). Tag me on it and we can continue there.