RFR: 8352075: Perf regression accessing fields [v3]

[Ioi Lam]

On Wed, 21 May 2025 15:03:51 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Thanks for the pointers; in fact I had the problem with a (intermediate) variant that encoded the symbol addresses right into the stream. Therefore the issue was comparing value of symbol values before CDS persisting those and after dehydration. Since we're comparing only symbols within single class, I hope that the issue you describe above won't happen. I'll keep the problem with dynamic archives in mind, though.
>> With the current code I can try using `fast_compare` again and get back if I find any problems again.
>
> Even if the fields are only defined within the same class, the names of the fields are shared among different classes.

To validate that you have sorted the table correctly, you should add a debug-only validation function. This function should be called after `set_fieldinfo_search_table()`, and also in `InstanceKlass::restore_unshareable_info()` and `InstanceKlass::remove_unshareable_info()`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24847#discussion_r2100546703