RFR: 8329603: G1: Merge G1BlockOffsetTablePart into G1BlockOffsetTable [v3]

[Albert Mingkun Yang]

On Mon, 8 Apr 2024 15:28:46 GMT, Ivan Walulya <iwalulya at openjdk.org> wrote:

>> Guoxiong Li has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Remove unnecessary comments.
>>  - Fix indentation issue.
>
> src/hotspot/share/gc/g1/g1HeapRegion.hpp line 77:
> 
>> 75:   HeapWord* volatile _top;
>> 76: 
>> 77:   G1BlockOffsetTable* _bot;
> 
> I suppose there is no longer a reason for this to be part of the region. Any downside to referring to it using `g1h->bot()`?

That would require calling `G1CollectedHeap::heap()` every time bot is needed. Actually, maybe some methods, e.g. `update_bot_for_block` should belong to heap, instead of heap-region.

(Either way, I feel this decision can/should be made in its own ticket.)

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PR Review Comment: https://git.openjdk.org/jdk/pull/18634#discussion_r1556055383