RFR: 8257815: Replace global log2 functions with efficient implementations [v9]

[Claes Redestad]

On Thu, 10 Dec 2020 09:55:07 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Claes Redestad has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 24 additional commits since the last revision:
>> 
>>  - Merge branch 'master' of https://github.com/openjdk/jdk into log2_template
>>  - More review comments adressed
>>  - Issue with using count_trailing_zeros with 64-bit values on 32-bit, revert and add TODO
>>  - Merge branch 'master' into log2_template
>>  - Renaming, adress review comments
>>  - x->value
>>  - Rename log2i ilogi and make it only accept value > 0, rename log2i_allow_zero log2i_graceful, accepting any value
>>  - Rename exact_log2i exact_ilog2, make it stricter
>>  - Merge branch 'master' into log2_template
>>  - Merge branch 'master' of https://github.com/openjdk/jdk into log2_template
>>  - ... and 14 more: https://git.openjdk.java.net/jdk/compare/bfe6d606...511a8f67
>
> Marked as reviewed by kbarrett (Reviewer).

@kimbarrett @stefank - thank you for reviews!

@tstuefe - re-testing latest on BE (ppc and s390?) would be much appreciated. I'm going to hold off on pushing this until some time after 16 forks off, so there's no rush.

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PR: https://git.openjdk.java.net/jdk/pull/1663