RFR: 8318480: UseCounterDecay and CounterDecayMinIntervalLength are unused and should be removed

[Tobias Hartmann]

On Wed, 15 Nov 2023 09:40:46 GMT, Daniel Lundén <duke at openjdk.org> wrote:

> This changeset deprecates the leftover (i.e., no longer used for anything) product compiler flag `UseCounterDecay` (requires CSR) and removes the leftover develop flag `CounterDecayMinIntervalLength`.
> 
> Changes:
> - Deprecate `UseCounterDecay` in JDK 22, obsolete it in JDK 23, and expire it in JDK 24. The flag is, in fact, already obsolete, so I've also removed it from the source code (except for the definition in `globals.hpp` which must remain until obsoletion).
> - Completely remove `CounterDecayMinIntervalLength`.
> 
> ### Testing
> Platforms: windows-x64, linux-x64, linux-aarch64, macosx-x64, macosx-aarch64.
> - `tier1`
> - HotSpot parts of `tier2` and `tier3`

I think the description of `UseCounterDecay` in globals.hpp should be changed to `"Adjust recompilation counters (deprecated)"`

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PR Review: https://git.openjdk.org/jdk/pull/16673#pullrequestreview-1731989319