RFR: 8332105: Exploded JDK does not include CDS [v2]

[Ioi Lam]

On Mon, 17 Jun 2024 06:39:45 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> An exploded JDK cannot be used with either -Xshare:on or -Xshare:auto. That causes tests like runtime/CompressedOops/CompressedCPUSpecificClassSpaceReservation.java to fail when running on an exploded JDK.
>> 
>> Since an exploded JDK cannot use CDS, we should - for tests - treat it as if CDS had not been included.
>> 
>> 
>> ----
>> 
>> Note that I was torn between two ways to fix this:
>> 
>> - either this fix, which is rather simple and automatically updates the "vm.cds" `@requires` property
>> - or to expose "exploded-ness" as a boolean property via `WhiteBox` and `VMProps`(`jdk.exploded`). See this draft PR: https://github.com/openjdk/jdk/pull/19178 . 
>> 
>> The latter is cleaner and clearer, conveying the message of exploded-ness without muddling it with the CDS aspect. But OTOH the complexity may not be required. 
>> 
>> I can go either way, though I have a slight preference for this PR, which is why I posted it.
>
> Thomas Stuefe has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
> 
>  - Merge branch 'openjdk:master' into JDK-8332105-Exploded-JDK-should-count-as-if-CDS-had-not-been-included-in-the-build
>  - JDK-8332105-Exploded-JDK-should-count-as-if-CDS-had-not-been-included-in-the-build

LGTM

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Marked as reviewed by iklam (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/19188#pullrequestreview-2123409301