RFR: 8316694: Implement relocation of nmethod within CodeCache [v3]

[Chad Rakoczy]

On Fri, 14 Mar 2025 22:03:44 GMT, Dean Long <dlong at openjdk.org> wrote:

>> Chad Rakoczy has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Share immutable data between copied nmethods
>
> src/hotspot/share/code/nmethod.hpp line 587:
> 
>> 585:   address immutable_data_references_begin      () const { return           _immutable_data + _immutable_data_references_offset   ; }
>> 586:   address immutable_data_references_end        () const { return            immutable_data_end(); }
>> 587: 
> 
> If we are going to add typed fields to this data, maybe we should put it in a struct/class header at the beginning so we can access the field directly?

@dean-long @vnkozlov I added `IMMUTABLE_DATA_REFERENCES` ([source](https://github.com/chadrako/jdk/blob/c5ff58f4e22cbbcdbe06997efe482f73fcee73f5/src/hotspot/share/code/nmethod.hpp#L577-L582)) to make the code more readable. Is that sufficient or would you like to see a struct to represent this instead?

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PR Review Comment: https://git.openjdk.org/jdk/pull/23573#discussion_r2114885140