RFR: 8368675: IGV: nodes are wrongly marked as changed in the difference view

[Marc Chevalier]

On Fri, 26 Sep 2025 08:34:34 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

> This changeset refines IGV's node difference analysis to ignore changes in node properties that are derived by IGV, as opposed to generated by HotSpot. Derived properties include the label and color of each node. Ignoring changes in these properties prevents IGV from wrongly marking equal nodes as "changed" (colored in yellow) when showing the difference between two graphs:
> 
> <img width="2323" height="651" alt="before-after" src="https://github.com/user-attachments/assets/ea51c86d-4719-45c0-b615-e6e4b8aec023" />
> 
> **Testing:** tier1 and manual testing on a few graphs.

Makes sense, looks good, will help!

I've actually already noticed such yellow nodes without change, and couldn't understand. I assumed the color code had some semantics I didn't know. That will be less confusing, thanks.

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Marked as reviewed by mchevalier (Committer).

PR Review: https://git.openjdk.org/jdk/pull/27515#pullrequestreview-3271513172