RFR: 8369793: G1: Remove unused G1FreeIdSet [v3]

[Kim Barrett]

On Tue, 14 Oct 2025 07:40:38 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

>> Hi all,
>> 
>>   please review this trivial removal of the unused `G1FreeIdSet` code. JEP 522 made it obsolete.
>> 
>> Testing: local compilation, gha
>> 
>> Thanks,
>>   Thomas
>
> Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:
> 
>   * remove more g1freeidset.cpp references from makefiles

Looks good.

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Marked as reviewed by kbarrett (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/27786#pullrequestreview-3334513091