RFR: 8365017: The SegmentBulkOperations::copy method can be improved [v9]

[Per Minborg]

On Wed, 20 Aug 2025 08:51:24 GMT, Per Minborg <pminborg at openjdk.org> wrote:

>> This PR proposes to use overlapping memory areas in `SegmentBulkOperations::copy`, similar to what is proposed for `SegmentBulkOperations::fill` in https://github.com/openjdk/jdk/pull/25383.
>> 
>> This PR passes `tier1`, `tier2`, and `tier3`testing on multiple platforms.
>
> Per Minborg has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Do not use overlapping copy

Let's come back when we have the Vector API available.

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PR Comment: https://git.openjdk.org/jdk/pull/26672#issuecomment-3209316699