RFR: 8292818: replace 96-bit representation for field metadata with variable-sized streams [v3]

[Frederic Parain]

On Mon, 13 Mar 2023 16:41:05 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Frederic Parain has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   SA additional caching from Chris Plummer
>
> src/hotspot/share/runtime/vmStructs.cpp line 2304:
> 
>> 2302:   declare_constant(FieldInfo::FieldFlags::_ff_generic)                    \
>> 2303:   declare_constant(FieldInfo::FieldFlags::_ff_stable)                     \
>> 2304:   declare_constant(FieldInfo::FieldFlags::_ff_contended)                  \
> 
> If there are flags that SA doesn't use, like contended, I don't think they should be included in the information that we pass to SA.

The contended flag is required to be able to decode the compressed stream, because it signals the presence of an optional part of a field description. The only flags that was not required for the decoding of the stream and was not used by the SA was Stable, and I'll remove it in the next commit.

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PR: https://git.openjdk.org/jdk/pull/12855