RFR: 8338566: Missing membar in ciEnv::get_or_create_exception before publishing handle [v2]

[Tobias Hartmann]

> Similar to [JDK-8251923](https://bugs.openjdk.org/browse/JDK-8251923), we need a store-store barrier before publishing a handle because otherwise another thread could observe the handle before it's fully initialized and read null from it. This affects architectures with a weak memory model like AArch64.
> 
> Unfortunately, this only happened twice in our testing and I was never able to reproduce it.
> 
> Thanks,
> Tobias

Tobias Hartmann has updated the pull request incrementally with one additional commit since the last revision:

  Create exceptions eagerly

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/20950/files
  - new: https://git.openjdk.org/jdk/pull/20950/files/5b4d9d11..155cd71d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20950&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20950&range=00-01

  Stats: 110 lines in 6 files changed: 41 ins; 63 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/20950.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20950/head:pull/20950

PR: https://git.openjdk.org/jdk/pull/20950