[lworld] RFR: 8367245: [lworld] C2 compilation fails with "Missed optimization opportunity in PhaseIterGVN"

[Roland Westrelin]

On Thu, 6 Nov 2025 09:17:39 GMT, Quan Anh Mai <qamai at openjdk.org> wrote:

> Additionally, an empty speculative type is supposed to mean that the path is speculatively unreachable,

Or that profile data for 2 different points in the execution is inconsistent which given how profile data is collected seems as likely to me.

Speculative types were added as a mechanism to fight profile pollution for scripting languages running on the JVM (specifically nashorn). They work really well in some cases. But they also have limited applicability. To me, it doesn't seem like a good use of developer time or our complexity budget to go with a complicated fix.

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PR Comment: https://git.openjdk.org/valhalla/pull/1717#issuecomment-3496151715