RFR: 8343218: Disable allocating interface and abstract classes in non-class metaspace

[Aleksey Shipilev]

On Thu, 31 Jul 2025 18:13:30 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> This change introduces a diagnostic flag to disable the change to allocate interface and abstract Klass metadata in the non-class metaspace.  Testing for JDK 25 has completed with this feature in place, but there may be cases where we should disable this.  A future change will be to remove this code.
> Tested with tier1-4 with the flag off, and 1-4 with the flag on.

Generally looks fine. Stylistic/process note, though: the RFE synopsis still reads that we are disabling the optimization. We are not doing it here, we are only guarding it with a flag. Either submit a new RFE or rename this bug?

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PR Review: https://git.openjdk.org/jdk/pull/26579#pullrequestreview-3079349456