Introduces Virtual Threads on s390x. Additionally contains changes from these Issues as well: 8338383: Implement JEP 491: Synchronize Virtual Threads without Pinning 8369238: Allow virtual thread preemption on some common class initialization paths
Testing: - [x] fastdebug : tier1 JTREG_TEST_THREAD_FACTORY=Virtual - [x] release : tier1 JTREG_TEST_THREAD_FACTORY=Virtual - [x] fastdebug: jdk_loom JTREG_TEST_THREAD_FACTORY=Virtual -XX:+TieredCompilation -XX:TieredStopAtLevel=1 -XX:+UnlockExperimentalVMOptions -XX:+VerifyContinuations - [x] fastdebug : jdk_loom JTREG_TEST_THREAD_FACTORY=Virtual -XX:-TieredCompilation -Xcomp -XX:+UnlockExperimentalVMOptions -XX:+VerifyContinuations - [x] fastdebug : hotspot_loom JTREG_TEST_THREAD_FACTORY=Virtual + -Xint - [x] fastdebug : hotspot_loom JTREG_TEST_THREAD_FACTORY=Virtual -XX:+TieredCompilation -XX:TieredStopAtLevel=1 -XX:+UnlockExperimentalVMOptions -XX:+VerifyContinuations - [x] fastdebug : hotspot_loom JTREG_TEST_THREAD_FACTORY=Virtual -XX:+TieredCompilation -XX:TieredStopAtLevel=1 -Xcomp -XX:+UnlockExperimentalVMOptions -XX:+VerifyContinuations --------- - [x] I confirm that I make this contribution in accordance with the [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). ------------- Commit messages: - updates copyright header, remove trailing space and unused functions - 8286300: Port JEP 425 to S390X Changes: https://git.openjdk.org/jdk/pull/31441/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=31441&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8286300 Stats: 1955 lines in 37 files changed: 1618 ins; 95 del; 242 mod Patch: https://git.openjdk.org/jdk/pull/31441.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/31441/head:pull/31441 PR: https://git.openjdk.org/jdk/pull/31441
