RFR: 8367967: C2: "fatal error: Not monotonic" with Mod nodes

[Christian Hagedorn]

On Sun, 21 Sep 2025 06:11:11 GMT, Hannes Greule <hgreule at openjdk.org> wrote:

> Generally, we shouldn't return a wider type (ZERO) if there is a later case that would return a more narrow type (TOP) for the same input types. If the inputs are widened and the first case doesn't match anymore but the later one still does, the result is not monotonic with the previous result.
> 
> Please review :)

The fix looks good to me, thanks for the fix and the credit for the test!

I'll give it a spin in our testing as well.

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Marked as reviewed by chagedorn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/27408#pullrequestreview-3250859104