RFR: 8318446: C2: optimize stores into primitive arrays by combining values into larger store [v11]

[Emanuel Peter]

On Fri, 23 Feb 2024 18:14:29 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> I don't know. I have added a test now for that, but probably need more tests.
>> @vnkozlov @rwestrel  do you think I need to do something about this?
>
> Yes, this could be the issue if we don't check that memory accesses offset overlaps.
> 
> There was issue we recently fixed [#16015](https://github.com/openjdk/jdk/pull/16015) where we did not take into account wider memory access to array.

@vnkozlov Hmm, ok. You seem to say that it is mostly a question of bugs that exist elsewhere. But my change here would not really change things then, since we could always trigger those things with Unsafe anyway, right?

Or is there something intrinsically wrong about using **raw store**?

Is there any alternative for me here? @TobiHartmann suggested I could use CPU barriers.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16245#discussion_r1502650283