RFR: 8305895: Implement JEP 450: Compact Object Headers (Experimental) [v11]

[Thomas Stuefe]

On Wed, 11 Sep 2024 11:25:56 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> Roman Kennke has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix FullGCForwarding initialization
>
> src/hotspot/share/memory/metaspace/metablock.hpp line 48:
> 
>> 46: 
>> 47:   MetaWord* base() const { return _base; }
>> 48:   const MetaWord* end() const { return _base + _word_size; }
> 
> `assert(is_nonempty())`

Raises the question of why here and not in other accessors? 

Note that the only patch via which end() is called already asserts for non-empty-ness (MetaspaceArena::contains).

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PR Review Comment: https://git.openjdk.org/jdk/pull/20677#discussion_r1762985723