RFR: 8251462: Remove legacy compilation policy [v4]

[Igor Veresov]

On Fri, 22 Jan 2021 20:08:17 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> It's not so easy. You can have AOT or JVMCI enabled with -Xint. JVMCI code installs can be initiated not only as a result of method going through the compiler broker. Remember that you can run Graal in "host" mode, where it is a normal C1/C2 system (or may be just an interpreter); Truffle can work in a mode like that. And you can totally run with AOT and interpreter (without any JIT).
>
> I don't think so:
>> java -Xint -XX:+UnlockExperimentalVMOptions -XX:+EnableJVMCI -version
> Java HotSpot(TM) 64-Bit Server VM warning: JVMCI Compiler disabled due to -Xint.
> 
>> java -Xint -XX:+UnlockExperimentalVMOptions -XX:+UseAOT -XX:+PrintAOT -version
> Java HotSpot(TM) 64-Bit Server VM warning: -Xint is not compatible with AOT (switching AOT off)

You're right. Perhaps I was overly defensive. It doesn't hurt though, less potential surprises in the future (as you correctly noticed those are used to make sure there are no nmethods produced by any other compiler but C1).
Also you still can have a C1 and AOT combination.

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