When testing with fastdebug binaries, we run now into a lot of asserts on Linux/macOS/Windows (in HS tier1/2/3 tests) :

# Internal Error (/priv/jenkins/client-home/workspace/openjdk-jdk-dev-linux_x86_64-dbg/jdk/src/hotspot/share/gc/shenandoah/shenandoahClosures.inline.hpp:165), pid=24797, tid=24839
# Error: Shenandoah assert_correct failed; Object klass pointer invalid

# Internal Error (/priv/jenkins/client-home/workspace/openjdk-jdk-dev-linux_x86_64-dbg/jdk/src/hotspot/share/gc/shenandoah/shenandoahForwarding.inline.hpp:70), pid=80148, tid=80162
# Error: Shenandoah assert_correct failed; Object klass pointer invalid

# Internal Error (/priv/jenkins/client-home/workspace/openjdk-jdk-dev-macos_x86_64-dbg/jdk/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp:66), pid=74407, tid=45571
# Error: Shenandoah assert_correct failed; Object klass pointer invalid

Examples of failing tests
compiler/gcbarriers/UnsafeIntrinsicsTest.java#shenandoah
gc/class_unloading/TestClassUnloadingDisabled.java#id3
(and many more)

The issue might be related to JDK-8361712 .
Interesting detail, in our test - JVMs we have UseCompactObjectHeaders enabled by default :
- product(bool, UseCompactObjectHeaders, false, \
+ product(bool, UseCompactObjectHeaders, true, \