RFR: 8350006: IGV: show memory slices as type information

[Daniel Lundén]

On Thu, 13 Feb 2025 19:47:25 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

> This changeset extends the "Show types" filter in IGV to show the memory slice corresponding to each memory node. This information can be useful e.g. in the ongoing investigation of [JDK-8333393](https://bugs.openjdk.org/browse/JDK-8333393). Here is an example of a memory subgraph with the extended "Show types" filter enabled:
> 
> ![example](https://github.com/user-attachments/assets/1810a257-c6d6-4b6e-9638-5bbef1c48717)
> 
> #### Testing
> 
> - tier1 (windows-x64, linux-x64, linux-aarch64, and macosx-x64; release and debug mode).
> 
> - Tested IGV manually on a few selected graphs. Tested automatically that displaying thousands of graphs with the "Show types" filter enabled does not trigger any assertion failure (by enabling assertions, instrumenting IGV to display parsed graphs eagerly, and running `java -Xbatch -XX:-TieredCompilation -XX:PrintIdealGraphLevel=3`).

Looks good and useful.

It would be nice if we would not need to rely on parsing `dump_spec` for the required information, which is potentially quite fragile if `dump_spec`s ever change. Maybe, in the future, we could dump node information in a more structured manner? E.g., `dump_spec_json` or similar. I guess it's probably too much work for too little gain.

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Marked as reviewed by dlunden (Committer).

PR Review: https://git.openjdk.org/jdk/pull/23621#pullrequestreview-2617121231