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

[Christian Hagedorn]

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!

How can it be visualized inside the node? Have you adapted some filter? AFAIU, you only dump an additional node property which is shown in the IGV node properties view.

-------------

Marked as reviewed by chagedorn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24422#pullrequestreview-2745955268