[lworld] RFR: 8373494: [lworld] markWord preservation for ParallelGC [v3]

[Stefan Johansson]

On Fri, 12 Dec 2025 09:40:05 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

>> Joel Sikström has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Remove dev logging
>>  - Convert COH check to assert in safe_to_read_header
>
> src/hotspot/share/gc/parallel/psParallelCompact.cpp line 2279:
> 
>> 2277:       markWord mark = safe_mark_prototype(cur_addr, remaining_words);
>> 2278: 
>> 2279:       closure.do_addr(cur_addr, obj_size, mark);
> 
> The fact that `do_addr` calls a function named `words_remaining()` and the current code calculates a `remaining_words` feels a bit messy and it's not immediately obvious that this is correct. Is there a reason why this can't be handled from withing the `do_addr` function?

Yes, I agree, we overlooked that we had that information inside `do_addr`.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1785#discussion_r2613608356