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

[Christian Hagedorn]

On Fri, 12 Sep 2025 08:18:40 GMT, Emanuel Peter <epeter 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

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Marked as reviewed by chagedorn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/27249#pullrequestreview-3215461040