RFR: 8260589: Crash in JfrTraceIdLoadBarrier::load(_jclass*) [v3]

[Denghui Dong]

> hi,
> 
> Could I have a review of this fix?
> 
> If we run the following code snippet, will get a crash
> class JFRDemo {
>     public static void main(String[] args) {
>         Recording r = new Recording();
>         r.enable("MyEvent");
>         r.start();
> 
>         MyEvent event = new MyEvent();
>         event.begin();
>         event.clazz = long.class;
>         event.commit();
>     }
> }
> 
> class MyEvent extends Event {
> 
>     @Label("Class")
>     public Class clazz;
> }

Denghui Dong has updated the pull request incrementally with one additional commit since the last revision:

  improve patch

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2295/files
  - new: https://git.openjdk.java.net/jdk/pull/2295/files/0ba1623c..811690c0

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2295&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2295&range=01-02

  Stats: 13 lines in 3 files changed: 11 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2295.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2295/head:pull/2295

PR: https://git.openjdk.java.net/jdk/pull/2295