RFR: 8367483: C2 crash in PhaseValues::type: assert(t != nullptr) failed: must set before get - missing notification for CastX2P(SubL(x, y))

[Emanuel Peter]

On Fri, 12 Sep 2025 08:45:07 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> `CastX2PNode::Ideal` optimizes cases:
>> 
>> CastX2P(AddX(x, y)) -> AddP(CastX2P(x), y)
>> CastX2P(SubL(x, y)) -> AddP(CastX2P(x), SubL(0, y))
>> 
>> 
>> But the notification code `PhaseIterGVN::add_users_of_use_to_worklist` only adds `CastX2P` to the worklist for the `AddX` and not the `SubX` cases.
>> 
>> ---------------------------------------
>> 
>> A little brag: this is the second (unrelated, i.e. non aliasing) bug that `TestAliasingFuzzer.java` found. Fuzzing access to native MemorySegment seems to trigger new/rare patterns.
>
> Looks good and trivial, thanks for the update

@chhagedorn @benoitmaillard Thanks for the reviews!

I agree, the patch is quite trivial.
I'm risking a Friday afternoon integration, to make sure the CI does not fail on our stress job.

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PR Comment: https://git.openjdk.org/jdk/pull/27249#issuecomment-3284931070