Yesterday I found the problem why we get a VerifyError when running Eclipse with CACAO-OpenJDK, while HotSpot does not. It's again the MagicAccessorImpl class.
Snippet from sun/reflect/MagicAccessorImpl.java (I overlooked that when debugging the access-check bug):
The bug fix for 4486457 also necessitated disabling verification for this class and all subclasses, as opposed to just SerializationConstructorAccessorImpl and subclasses, to avoid having to indicate to the VM which of these dynamically-generated stub classes were known to be able to pass the verifier.
Finding these magics is really a pain...