RFR: 8251462: Remove legacy compilation policy [v5]

[Vladimir Kozlov]

On Sun, 24 Jan 2021 03:53:00 GMT, Igor Veresov <iveresov at openjdk.org> wrote:

>> This change removes the legacy compilation policy and an emulation mode to the tiered policy to simulate the old behavior with ```-XX:-TieredCompilation```. The change removed a bunch of interpreter code, devirtualizes the compilation policy API, adds a consistent way to query compiler configuration with the new ```CompilerConfig``` API.
>> 
>> I've tested this with hs-tier{1,2,3,4,5}. And also made sure it builds and works with C1/C2-Graal/AOT being enabled/disabled.
>> 
>> Since there are platform-specific changes I would greatly appreciate some help from the maintainers of the specific ports to verify the build and run basic smoke tests. I've already tested x64 and aarch64. Thanks!
>
> Igor Veresov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Address Vladimir's review comments

I approve it based on performance results.

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Marked as reviewed by kvn (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1985