RFR: 8305895: Implement JEP 450: Compact Object Headers (Experimental) [v6]

[Thomas Stuefe]

On Fri, 23 Aug 2024 16:23:19 GMT, Leonid Mesnik <lmesnik at openjdk.org> wrote:

>> Roman Kennke has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix bit counts in GCForwarding
>
> make/Images.gmk line 135:
> 
>> 133: #
>> 134: # Param1 - VM variant (e.g., server, client, zero, ...)
>> 135: # Param2 - _nocoops, _coh, _nocoops_coh, or empty
> 
> The -XX:+UseCompactObjectHeaders ssems to incompatible withe zero vm. The zero vm build start failing while generating shared archive with +UseCompactObjectHeaders. Generation should be disabled by default for zero to don't break the build.

No, zero works with +COH, but a small change is needed. I'll post a suggestion inline.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/20677#discussion_r1738119614