There is the aarch64-only addition in instanceKlass.cpp here:
 https://hg.openjdk.java.net/aarch64-port/jdk8u-shenandoah/hotspot/file/6e4f992250b5/src/share/vm/oops/instanceKlass.cpp#l3118

It was used for debugging and shows up as deviation from 8u upstream. We should revert it and optionally get the block like that via normal backporting path.