RFR: 8319879: Stress mode to randomize incremental inlining decision [v3]

[Tobias Hartmann]

On Thu, 16 Nov 2023 14:39:06 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

>> We had quite a few C2 bugs in the past that only reproduced with a specific sequence of incremental inlining (for example, [JDK-8319764](https://bugs.openjdk.org/browse/JDK-8319764)). We should randomize the incremental inlining decision to trigger these code paths more frequently.
>> 
>> I did some testing with the flag enabled and I hit [JDK-8319764](https://bugs.openjdk.org/browse/JDK-8319764) and [JDK-8319889](https://bugs.openjdk.org/browse/JDK-8319889). I think it's still valuable to integrate this even if these bugs are not resolved yet.
>> 
>> Thanks,
>> Tobias
>
> Tobias Hartmann has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Moved the should_delay check up

I executed a lot of testing up to and including tier7 + stress testing with `-XX:+StressIncrementalInlining` and found several bugs that I linked to [JDK-8319879](https://bugs.openjdk.org/browse/JDK-8319879). It turned out that the `compiler/cha/*`tests do fail but the failure is intermittent. I filed an issue for that as well.

I think that proves the value of this stress flag and given that these bugs are independent of the stress flag implementation, I propose to integrate it even if these issues are still unresolved.

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PR Comment: https://git.openjdk.org/jdk/pull/16597#issuecomment-1816552558