Update: Resolved. Hotspot doesn't link the class when creating a j.l.Class instance. That occurs later. When forcing the class to be linked, the preload occurs.

Playing with the preload classfile attribute and seeing some strange behaviour.

1. Build a JDK from the valhalla repo and the lworld branch
2. Compile A.java and B.java.value to get a preload attribute in A.class
3. Compile B.java to convert it to a non-value class
4. Run test case Test1 and see the preload attribute in use:

$ ../build/macosx-x86_64-server-release/jdk/bin/java  -Xlog:class+preload=debug:stdout -XX:+EnableValhalla  Test1

==== Preloading classes during linking of class A because of its Preload[1] attribute
Preloading class B during linking of class A because of its Preload attribute
[0.191s][info][class,preload] Preloading class B during linking of class A because of its Preload attribute
main

1. Run LoaderTest to see preload on a user-defined classloader

$ ../build/macosx-x86_64-server-release/jdk/bin/java  -Xlog:class+preload=debug:stdout -XX:+EnableValhalla  LoaderTest A
2-loadClass:A:::false
2-loadClass:arg0:A:::false
1-loadClass:java.lang.Object
2-loadClass:java.lang.Object:::false
class A::loader=LoaderTest@4cb2c100

Neither my debugging printfs or the Xlog output shows the preload attribute is being used with the user-defined classloader