[11u] RFR(S): 8241234: Unify monitor enter/exit runtime entries.

[Doerr, Martin]

Hi,

I'd like to backport https://bugs.openjdk.java.net/browse/JDK-8241234 to JDK11u.

Original JDK15 patch (https://hg.openjdk.java.net/jdk/jdk/rev/87c506c8be63) doesn't fit to JDK11u because the locking code has been reworked by https://bugs.openjdk.java.net/browse/JDK-8229844
As mentioned by Vladimir, there's already a GraalVM version available which consists of 2 patches (original + addon) and which can be applied:
https://github.com/graalvm/labs-openjdk-11/commit/6c162cb15262e6aa77e36eb3a268320ef0a206a4
https://github.com/graalvm/labs-openjdk-11/commit/6a28a618cdbe595f9a3993e0eb63c01ccae1a528
Only JVMCI part from GraalVM doesn't apply automatically. The version of this file from JDK15 is very simple and fits perfectly.

Please review the JDK11u backport webrev:
http://cr.openjdk.java.net/~mdoerr/8241234_monitorenterexit_11u/webrev.00/

Thanks and best regards,
Martin