RFR: 8308088: Improve class check in CollectedHeap::is_oop [v2]

[Aleksey Shipilev]

> See the bug for more details.
> 
> Additional testing:
>  - [x] Linux x86_64 fastdebug, `tier1`
>  - [x] Linux x86_64 fastdebug, `tier2`
>  - [x] Linux x86_64 fastdebug, `tier3`

Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:

  Avoid touching klass racily (even for v-call)

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/13982/files
  - new: https://git.openjdk.org/jdk/pull/13982/files/b3b41441..983ee9f8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13982&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13982&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13982.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13982/head:pull/13982

PR: https://git.openjdk.org/jdk/pull/13982