RFR: 8365256: RelocIterator should use indexes instead of pointers [v3]

[Johan Sjölen]

On Fri, 22 Aug 2025 09:10:16 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> Hi,
>> 
>> This PR replaces the `current` and `end` pointers with a `base` pointer alongside a `current` index and a `len`. This allows us to have `-1` as the initial value for current, while retaining `nullptr` as the 'dead' value for `_mutable_data`.
>> 
>> Performance testing shows no difference/performance improvements on DaCapo Linux x64. I don't think that these are actual improvements, but at least there are no clear regressions.
>> 
>> Testing: GHA
>
> Johan Sjölen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Make constructor private

Thank you for the reviews

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PR Comment: https://git.openjdk.org/jdk/pull/26569#issuecomment-3227184307