Revised JEP and JVMS: Flattened Heap Layouts for Value Objects

[Arne Siegel]

Hi,

regarding the "implements NonAtomic" approach, what about the corner case
where a class implementing NonAtomic contains a field of a second value
type not implementing NonAtomic? Special measurements in the JVM will be
necessary to guarantee the intention of the second value type's author.

Best regards
Arne Siegel

Am Mi., 3. Mai 2023 um 04:06 Uhr schrieb Dan Smith <daniel.smith at oracle.com
>:

> JEP 401 has been updated to reflect our most recent discussions about
> deriving flattening from nullness and value class properties. Now calling
> this feature "Flattened Heap Layouts for Value Objects".
>
> https://openjdk.org/jeps/401
>
> I've also put together a revised JVMS document to specify the needed JVM
> attributes.
>
>
> https://cr.openjdk.org/~dlsmith/jep401/jep401-20230428/specs/flattened-heap-jvms.html
>
> This approach to the JVM avoids any use of 'Q' types in class files, which
> we decided had too much overhead for our limited needs.
>
> At this stage, there's no JVMS feature to support flattened array
> creation. Instead, these are created by passing Class objects representing
> null-restricted types to the 'Array.newInstance' methods.
>
>
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