The PrintFieldLayout flag prints all the field layouts in all the classes loaded as they are parsed. This is really noisy and you can see the field layout of the InstanceKlass once it's created with the InstanceKlass::print() function.

It might be kind of useful to see how big the preinitialized classes are?

Seems to have been added with:

changeset: 3995:4a916f2ce331
user: jwilhelm
date: Mon Jan 14 15:17:47 2013 +0100
summary: 8003985: Support @Contended Annotation - JEP 142