RFR: 8353669: IGV: dump OOP maps for MachSafePoint nodes

[Tobias Hartmann]

On Thu, 3 Apr 2025 18:20:15 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

> This changeset dumps the OOP map of each MachSafePoint when available, i.e. at the `Final Code` phase. This should make it easier to learn about and diagnose OOP map building issues:
> 
> ![final-code](https://github.com/user-attachments/assets/a477c9d1-0fe4-42ef-a367-336c54bec6a5)
> 
> #### Testing
> 
> - tier1 (windows-x64, linux-x64, linux-aarch64, macosx-x64, and macosx-aarch64; release and debug mode).
> - Tested IGV manually on a few selected graphs. Tested automatically that dumping thousands of graphs does not trigger any assertion failure (by running `java -Xcomp -XX:PrintIdealGraphLevel=1`).

Looks good to me too.

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Marked as reviewed by thartmann (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24422#pullrequestreview-2749074037