JEP-450 Review Todo

• Thomas Stuefe Create a temporary shadow branch to push review fixes
  Done: https://github.com/openjdk/lilliput/tree/JEP-450-temporary-fix-branch
  • Thomas Stuefe Crash in many appcds tests, eg, runtime/cds/appcds/ParallelLoadTest.java +COH CDS metaspace. Reason was a missing mutex lock.
    
  • Thomas Stuefe Crash in runtime/cds/appcds/TestParallelGCWithCDS. Reason possibly a merge conflict with the recent array slicing changes in Parallel
• Tests broken when UCOH is on by default
  • Stefan Karlsson Fix TestAutoCreateSharedArchiveNoDefaultArchive 
  • Thomas Stuefe tools/jlink/plugins/CDSPluginTest.java complains about classes.jsa is not found (only the _coh.jsa files are present)
    
  • Thomas Stuefe compiler/c2/irTests/TestPadding.java
    

  • Thomas Stuefe runtime/cds/appcds/loaderConstraints/DynamicLoaderConstraintsTest.java#custom-cl-zgc-generational  - Broken when -Xshare:off is passed in as a test option

Address PR review comments

• Thomas Stuefe TinyCP: find a better way to deal with zero 
  
• Thomas Stuefe tiny_classpointer_mode() - find a better name. Potentially, wire it directly to +COH instead of an own flag. https://github.com/openjdk/jdk/pull/20677/files/70f492d381efad303a4941b2ca4403a4ad277fbb#r1750515923
• Thomas Stuefe remove mentioning of "legacy" https://github.com/openjdk/jdk/pull/20677/files/70f492d381efad303a4941b2ca4403a4ad277fbb#r1750524690
• Thomas Stuefe Improve comment in  CompressedKlassPointers::check_valid_klass https://github.com/openjdk/jdk/pull/20677/files/70f492d381efad303a4941b2ca4403a4ad277fbb#r1750662637

• Thomas Stuefe Merge up to and including https://bugs.openjdk.org/browse/JDK-8340184
  
• Thomas Stuefe Fix runtime/CompressedOops/CompressedClassPointersEncodingScheme.java (linux aarch)
  
• Thomas Stuefe Fix: (likely all the same issues)
  jdk/jfr/event/gc/objectcount/TestObjectCountAfterGCEventWithG1ConcurrentMark.java
  jdk/jfr/event/gc/objectcount/TestObjectCountAfterGCEventWithG1FullCollection.java
  jdk/jfr/event/gc/objectcount/TestObjectCountAfterGCEventWithParallelOld.java
  jdk/jfr/event/gc/objectcount/TestObjectCountAfterGCEventWithSerial.java
  jdk/jfr/event/gc/objectcount/TestObjectCountEvent.java