On Tue, 19 May 2026 10:59:30 GMT, Manuel Hässig <[email protected]> wrote:

>> This PR updates the Test `compiler/stable/TestStableArrayMembars.java` for 
>> Valhalla. This involves creating a code path for migrated value classes and 
>> a slight change to C2 to be able to clean up more barriers than previously.
>> 
>> Unfortunately, with `--enable-preview` C2 is not able to fully clean up all 
>> membars as it is for mainline. This is due to the later elision of the 
>> loads. After parsing, membars do not carry information that could relate 
>> them to any particular memory access, so we cannot remove them without 
>> potentially violating the JMM. Further, the implementation of 
>> `Unsafe.getFlatValueAcquire` emits a barrier in Java that cannot be 
>> eliminated by the JIT anyways.
>> 
>> Testing:
>>  - [x] tier1,tier2 and additional stress testing.
>> 
>> ---------
>> - [x] I confirm that I make this contribution in accordance with the 
>> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai).
>
> Manuel Hässig has updated the pull request incrementally with one additional 
> commit since the last revision:
> 
>   Update test/hotspot/jtreg/compiler/stable/TestStableArrayMembars.java
>   
>   Co-authored-by: Tobias Hartmann <[email protected]>

@mhaessig 
Your change (at version af60ed6041623353cc3c74ab5f0b96b115eab0aa) is now ready 
to be sponsored by a Committer.

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

PR Comment: https://git.openjdk.org/valhalla/pull/2441#issuecomment-4487076932

Reply via email to