On Fri, 17 Apr 2026 08:43:36 GMT, Christian Hagedorn <[email protected]> 
wrote:

>> This patch fixes various issues found with abstract value classes where the 
>> assumption was that we have a concrete value class but we actually could 
>> have an abstract value class as well.
>> 
>> The main issue found is that a concrete value class is represented with an 
>> `InlineKlass` while an abstract value class is represented with an 
>> `InstanceKlass`. Therefore, we cannot cast the latter to `InlineKlass`. 
>> While working on this, I checked all `is_inlinetype()` uses and found more 
>> issues. I also found issues around the `Arrays.copyOf/copyOfRange` intrinsic 
>> but left it as follow-up work and filed 
>> [JDK-8382226](https://bugs.openjdk.org/browse/JDK-8382226) for it. 
>> 
>> Here is a list of fixes included in this patch, together with corresponding 
>> tests:
>> 1. `GraphKit::get_layout_helper()`: Wrong old assumption that nullable 
>> implies not-flat.
>> 2. Checking whether we have a load/store from/to a field of an empty value 
>> class:
>> a. C1: `GraphBuilder::access_field()`, for static and instance field.
>> b. C2: `Parse::do_get_xxx()`, for loading
>> c. C2: `Parse::do_set_xxx()`, for storing
>> 3. `arraycopy` instrinsic: Not bailing out when src or dest is a flat 
>> abstract value class array - in this case we don't know the layout. We 
>> currently hit an assert due to an invalid cast, assuming concrete value 
>> classes when an array is flat.
>> 
>> Additional changes:
>> - Added some more asserts
>> - Some small code cleanups
>> 
>> Thanks,
>> Christian
>> 
>> ---------
>> - [x] I confirm that I make this contribution in accordance with the 
>> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai).
>
> Christian Hagedorn has updated the pull request incrementally with one 
> additional commit since the last revision:
> 
>   Dean's review

Thanks a lot, looks good to me.

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

Marked as reviewed by qamai (Committer).

PR Review: 
https://git.openjdk.org/valhalla/pull/2325#pullrequestreview-4127368703

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