RFR: 8329994: Zap alignment padding bits for ArrayOops in non-release builds [v3]

[Axel Boldt-Christmas]

On Thu, 20 Jun 2024 12:38:45 GMT, Axel Boldt-Christmas <aboldtch at openjdk.org> wrote:

>> In a similar vein to [JDK-8325870](https://bugs.openjdk.org/browse/JDK-8325870). Zap the any alignment padding that may exist between the header and the payload.
>> 
>> Currently this padding only occurs when disabling `UseCompressedClassPointers`. But becomes more relevant with [JDK-8294992](https://bugs.openjdk.org/browse/JDK-8294992).
>
> Axel Boldt-Christmas 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 three additional commits since the last revision:
> 
>  - Merge branch 'openjdk:master' into JDK-8329994
>  - Rename to mem_zap_start_padding
>  - 8329994: Zap alignment padding bits for ArrayOops in non-release builds

Thanks for the reviews.

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PR Comment: https://git.openjdk.org/jdk/pull/18714#issuecomment-2185682363