[jdk21u-dev] RFR: 8318986: Improve GenericWaitBarrier performance [v4]

[Aleksey Shipilev]

> Clean backport to drastically improve safepoint performance under heavy load, fixing regression between JDK 11 and JDK 17.
> 
> Additional testing:
>  - [x] Ad-hoc performance runs, expected improvements
>  - [x] MacOS AArch64 server fastdebug, `all` tests

Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Merge branch 'master' into JDK-8318986-generic-wait-barrier
 - Merge branch 'master' into JDK-8318986-generic-wait-barrier
 - Backport 30462f9da40d3a7ec18fcf46e2154fabb5fd4753

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

Changes:
  - all: https://git.openjdk.org/jdk21u-dev/pull/70/files
  - new: https://git.openjdk.org/jdk21u-dev/pull/70/files/2aada3b9..17d9b6e6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=70&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=70&range=02-03

  Stats: 15035 lines in 265 files changed: 6918 ins; 4061 del; 4056 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/70.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/70/head:pull/70

PR: https://git.openjdk.org/jdk21u-dev/pull/70