[lworld] RFR: 8367242: [lworld] C2 compilation asserts with "dead loop detected" [v2]

[Tobias Hartmann]

On Tue, 30 Sep 2025 23:37:51 GMT, Marc Chevalier <mchevalier at openjdk.org> wrote:

>> Right, skipping the call would be even better. I think the `ensure_phi` callsite should be fine as well as all the branches that the phi inputs correspond to should either be initialized afterwards or are dead (in which case `top` seems appropriate). But only testing will tell :D
>
> I didn't dig too much, but it seems that if one put top everywhere in `clone_with_phis`, between a quarter and a third of all the tests are broken. Anyway, it doesn't seem good. But making this callsite init the inputs of the phi with top seems to simplify our life and seems to work.

Okay, interesting. Maybe one of the Phis is folded too early or something. Could be worth investigating separately but out of scope for this issue.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1640#discussion_r2393675419