RFR: 8374582: [REDO] Move input validation checks to Java for java.lang.StringCoding intrinsics [v2]

[Damon Fenacci]

On Tue, 27 Jan 2026 09:24:34 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> Fair enough — I was just curious.
>
> I was about to ask the same question. It seems like both `OpaqueNotNullNode` and `OpaqueGuardNode` behave the same apart from eventually folding to a false or true constant. They might have slightly different reasons for adding them but AFAIU, they are both intended to keep control and data in sync. Apart from duplicating most of the logic and comments, an additional challenge with having both nodes is that we need to special case both nodes at various points in the code which makes it more complex and raises the question if we could really observe them both or not (would not be a problem when only having one node type).

Thanks for reviewing @chhagedorn.

> special case both nodes at various points

Good point. I guess better have only one after all. Changed. (I called it `OpaqueCheck` for lack of a better idea)

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PR Review Comment: https://git.openjdk.org/jdk/pull/29164#discussion_r2732811990