[lworld] Integrated: 8355317: [lworld] C2 Runtime load_unknown_inline should not return null-free type

[Tobias Hartmann]

On Wed, 23 Apr 2025 12:08:01 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

> We incorrectly mark the result of `load_unknown_inline` as null-free which is not correct anymore after [JDK-8341767](https://bugs.openjdk.org/browse/JDK-8341767) because nullable arrays can now be flat as well.
> 
> I also noticed that the optimization added by [JDK-8228622](https://bugs.openjdk.org/browse/JDK-8228622) assumes that when we load from an unknown array and then cast the result to a non-value class, we can deduce that the array is not flat if the cast succeeds. That only applies to null-free, flat but not to nullable, flat arrays because null will pass the cast. I filed [JDK-8355382](https://bugs.openjdk.org/browse/JDK-8355382) to follow up on this.
> 
> Thanks,
> Tobias

This pull request has now been integrated.

Changeset: ad591c50
Author:    Tobias Hartmann <thartmann at openjdk.org>
URL:       https://git.openjdk.org/valhalla/commit/ad591c50055e019885dcfc9c98d16c30b4fc9c7e
Stats:     60 lines in 5 files changed: 51 ins; 2 del; 7 mod

8355317: [lworld] C2 Runtime load_unknown_inline should not return null-free type

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PR: https://git.openjdk.org/valhalla/pull/1441