RFR: 8265129: Add intrinsic support for JVM.getClassId [v4]

[Denghui Dong]

On Sat, 8 May 2021 06:52:13 GMT, Denghui Dong <ddong at openjdk.org> wrote:

>> 8265129: Add intrinsic support for JVM.getClassId
>
> Denghui Dong has updated the pull request incrementally with one additional commit since the last revision:
> 
>   swap the positions of two operands in cmp operation since the det register will be modified in 32 bit

A reason why I think this method should be intrinsic:

Some of our instrumentation agents use JFR to record some key information, for example, the actual type of parameters or result. and in actual scenarios, a specific type is often used multiple times.
And there are obviously fast and slow paths in the implementation of JfrTraceId::load.
Therefore, intensifying this method will decrease the overhead for this usage.

-------------

PR: https://git.openjdk.java.net/jdk/pull/3470