RFR: 8350006: IGV: show memory slices as type information [v2]

[Roberto Castañeda Lozano]

On Fri, 14 Feb 2025 10:05:45 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`).
>
> Roberto Castañeda Lozano has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Increase property print buffer to avoid truncating dump_spec

@chhagedorn reported offline that the slice of `MergeMem` nodes is sometimes missing (thanks for the report!). This is due to HotSpot truncating the `dump_spec` property value, which can be particularly verbose for wide `MergeMem` nodes. Commit 53258db4 increases the size of the (debug-only) HotSpot buffer from 512 to 2048 characters, which should be sufficient for most practical cases.

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

PR Comment: https://git.openjdk.org/jdk/pull/23621#issuecomment-2658846714