RFR: 8318966: Some methods make promises about Java array element alignment that are too strong

[Maurizio Cimadamore]

On Thu, 16 Nov 2023 19:15:25 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> But... surely if I'm just accessing bytes the access cannot possibly be mis-aligned?
>
> Right. I think there is a difference between 'unaligned' and 'misaligned'. Unaligned means there is no effort made to align the access (so it _may_ be misaligned). Misaligned means _definitely not_ aligned. At least, that is my interpretation.
> 
> This is what I wrote in the latest version:
> 
> 
>      * For heap byte buffers, access is always unaligned. As a result, only the plain
>      * {@linkplain VarHandle.AccessMode#GET get}
>      * and {@linkplain VarHandle.AccessMode#SET set} access modes are supported by the
>      * returned var handle. For all other access modes, an {@link IllegalStateException}
>      * will be thrown.

Uhm, I think my assumption was wrong - the `byte`/`boolean` carrier is not supported by this method, so there's no case where heap access would be guaranteed to be aligned.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/16681#discussion_r1396221179