RFR: 8377008: [REDO] G1: Convert remaining volatiles in G1ConcurrentMark to Atomic<T> [v2]

[Thomas Schatzl]

> Hi all,
> 
>   please review this change that reverts the backout from https://bugs.openjdk.org/browse/JDK-8377000 (first commit) and adds a simple fix to make TAMSes be initialized properly (second commit) and removes an obsolete assert (third commit).
> 
> After https://bugs.openjdk.org/browse/JDK-8371720 TAMSes are reinitialized when starting up concurrent mark at the first GC, losing all previously generated information for previously allocated memory.
> 
> The change just adds initialization of all the TAMSes for all active regions. In a follow-up I am preparing a more comprehensive change/cleanup that limits TAMS use to the marking process only so that we can initialize concurrent mark data structures even more lazily.
> 
> Testing: gha, tier1-5
> 
> Thanks,
>   Thomas

Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:

  * remove debugging logs in tests

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/29653/files
  - new: https://git.openjdk.org/jdk/pull/29653/files/5cd0fc87..bd5b7daf

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29653&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29653&range=00-01

  Stats: 3 lines in 2 files changed: 0 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/29653.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29653/head:pull/29653

PR: https://git.openjdk.org/jdk/pull/29653