RFR: 8344247: Move objectWaiter field to VirtualThread instance

Thu Nov 14 22:51:18 UTC 2024

Small follow-up change after JDK-8338383. This moves the `objectWaiter` field from the stackChunk to the VirtualThread instance. Only the top stackChunk uses this field so we could save some memory by just saving it in the virtual thread instance instead. Also, related methods `stackChunkOopDesc::current_pending_monitor` and `stackChunkOopDesc::current_waiting_monitor` are moved to the `java_lang_VirtualThread` class where they naturally belong, since these are the equivalent of the JavaThread methods but for an unmounted vthread.
Tested by running mach5 tiers1-3.

Thanks,
Patricio

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Commit messages:
 - v1

Changes: https://git.openjdk.org/jdk/pull/22124/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22124&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344247
  Stats: 115 lines in 12 files changed: 39 ins; 62 del; 14 mod
  Patch: https://git.openjdk.org/jdk/pull/22124.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22124/head:pull/22124

PR: https://git.openjdk.org/jdk/pull/22124