Sometimes it is easier to test JDK by building it with
 -XX:+UseCompactObjectHeaders
enabled by default. The option is transparent for all tests and even flagless tests are executed.

Test runtime/CompressedOops/CompressedClassPointersEncodingScheme.java
start failing because expects to be executed with -XX:-UseCompactObjectHeaders

It would be fine to support JDK build with -XX:+UseCompactObjectHeaders