RFR: 8327240: Remove unused Tier2CompileThreshold/Tier2BackEdgeThreshold product flags

[Christian Hagedorn]

On Mon, 22 Apr 2024 20:23:49 GMT, Sonia Zaldana Calles <szaldana at openjdk.org> wrote:

> Hi all, 
> 
> This PR removes the unused options ```Tier2CompileThreshold``` and ```Tier2BackEdgeThreshold```. 
> 
> Testing: 
> - [x] Verified unrecognized option error is reported after removing options. 
> 
> Thanks, 
> Sonia

I had a quick look at the git history. The only use of `Tier2CompileThreshold` that has been around since initial load was removed with https://github.com/openjdk/jdk/pull/888. For `Tier2BackEdgeThreshold`, the only use was removed when tiered compilation was introduced with [JDK-6953144](https://bugs.openjdk.org/browse/JDK-6953144). There is, however, a single test that uses `Tier2BackEdgeThreshold` which should also be updated if these flags are going to be removed:
https://github.com/openjdk/jdk/blob/20546c1ea064daa8e2faa71142904ea2c62b3311/test/hotspot/jtreg/vmTestbase/jit/t/t105/t105.java#L34

This suggests that it's fine to remove these. But maybe @veresov can comment on this.

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PR Comment: https://git.openjdk.org/jdk/pull/18904#issuecomment-2074223780