RFR (M): JDK-8004967 - Default method cause java.lang.VerifyError: Illegal use of nonvirtual function call

Bharadwaj Yadavalli bharadwaj.yadavalli at oracle.com
Fri Jan 18 13:52:37 PST 2013

Hi Coleen,

Thanks for the review.

On 1/18/2013 2:28 PM, Coleen Phillimore wrote:
> I think the extra check in the old verifier that the ACC flags are set 
> is going to cause a headache if we change the VM to change which 
> special ACC flags are set.   I think the check should be in 
> JVM_IsVMGeneratedMethod() instead, and not check in the old verifier.

The reason I kept the access flag check separate is to maintain a 
consistent check for overpass method in old and new verifiers.

A method is considered overpass if the method type is 
ConstMethod::OVERPASS (see Method::is_overpass()) - a property not 
dependent on its access flags. The new verifier checks for overpass 
methods to decide whether to trust the code or not; additional access 
flag check is not done in the new verifier.

I intend JVM_IsVMGeneratedMethodIx() to be functionally equivalent to 
Method::is_overpass(). To achieve this, my implementation of 
JVM_IsVMGeneratedMethodIx() basically returns (method->method_type() == 
ConstMethod::OVERPASS) - which is what Method::is_overpass() also does. 
To minimize any divergence, I now updated the implementation of 
JVM_IsVMGeneratedMethodIx() to call is_overpass().  This will ensure 
ultimately the same query is used to test for overpass methods by the 
old and new verifiers.

Regarding checking of access flags: JVM_IsVMGeneratedMethodIx() pertains 
to the method type and has nothing to do with access flags. A generated 
method could have more than one legal set of access flags. Separately, 
JVM_GetMethodIxModifiersIx() provides the API to query method access 
flags and is not related to method type. I think, the functionality of 
these two APIs should not be mixed. If a decision needs to be made based 
on method type and access flags, I believe, separate queries should be 
used (as is done in the code currently under review).

As I noted in the code comments, I am just  performing an additional 
access flag check in the old verifier (which can also be potentially 
added in new verifier).

> I think you have to file a CCC request to add this function.

What are the criteria to file for a CCC? What are the circumstances 
under which one needs to be filed?



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