RFR: 8376604: C2: EA should assert is_oop_field for AddP with oop outs

[Quan Anh Mai]

On Wed, 28 Jan 2026 18:30:15 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Split out of [JDK-8376514](https://bugs.openjdk.org/browse/JDK-8376514) in Valhalla: I think we need to verify more thoroughly that if we reply is_oop_field = false for AddP, then there are no nodes that we feed into oops. We handle it pretty well in various branches in the method already, and we "just" need to check it at the end. Valhalla catches fire on that post-condition check, tracked in [JDK-8376514](https://bugs.openjdk.org/browse/JDK-8376514).
> 
> Cleans up the code a bit as well.
> 
> Additional testing:
>  - [x] Linux x86_64 server fastdebug, `applications/ctw/modules`
>  - [x] Linux x86_64 server fastdebug, `hotspot_compiler`

LGTM

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Marked as reviewed by qamai (Committer).

PR Review: https://git.openjdk.org/jdk/pull/29468#pullrequestreview-3722019313