RFR: 8371656: HashMap.putAll() optimizations [v3]

[Stuart Marks]

On Tue, 9 Dec 2025 16:38:44 GMT, jengebr <duke at openjdk.org> wrote:

>> jengebr 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 five additional commits since the last revision:
>> 
>>  - Merge branch 'openjdk:master' into putMapEntriesOptimizations
>>  - Unit test revisions
>>  - Bug fix & unit test
>>  - fixing whitespace
>>  - Optimizing HashMap.putAll() and .<init> for HashMap and C$UM
>
> @stuart-marks would you mind reviewing this one?  It's conceptually similar to the ArrayList modifications, but applied to different classes and most details differ.  I incorporated lessons about MOAT so that part should be cleaner.

@jengebr Oops! Sorry, you had asked me to review this but I dropped the ball over the holidays. If you'd like me to review it, please reopen.

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PR Comment: https://git.openjdk.org/jdk/pull/28243#issuecomment-3849345890