Comment 2 for bug 1742941

------- Comment From <email address hidden> 2018-01-12 08:22 EDT-------
>'ve created the following which hopefully contains all the features
> required to be upstream friendly.
>
> https://github.com/grooverdan/zlib/commits/power_crc32_c_version
>
> Most importantly compared to the previous PR, it contains the right crc32
> constants.
>
> If you see anything that upstream/distros or anyone else might nit about
> then please tell me (on github or here). The upstream isn't very active so
> presenting something idea on day one is my goal.
>
> Note 1: no clang currently due to...
>
> Note 1a: crc32_vpmsum: __builtin_pack_vector_int128 and
> __builtin_crypto_vpmsumw/__builtin_crypto_vpmsumd - need to review
> https://github.com/racardoso/crc32-vpmsum/commit/
> 97210b9188916eb46377b5eb927ae337948bf016 properly (sorry Rogerio, from
> memory it needs to compile fail for clang BE rather than generate wrong
> results).
>
> Note 1b: clang - no __builtin_cpu_supports (
> https://bugs.llvm.org/show_bug.cgi?id=35898 ) so I might fall back to
> getauxval
>
>
> Is there an better define than __powerpc__ to check in configure to detect
> Power8+ only?
>
> Other suggestions welcome.