RFR: 8232613: Move Object.registerNatives into HotSpot

[Lois Foltan]

On 10/22/2019 7:13 AM, Claes Redestad wrote:
>
>
> On 2019-10-22 13:05, Andrew Dinn wrote:
>> On 22/10/2019 12:05, Claes Redestad wrote:
>>> On 2019-10-22 12:44, Andrew Dinn wrote:
>>>> Why not leave it void?
>>>
>>> I guess:
>>>
>>> http://cr.openjdk.java.net/~redestad/8232613/open.02/
>> Ship it ;-)
>
> No wait, I missed the use in jni.cpp where the bool return is actually
> used. I ignored it in systemDict since when I got an exception there
> (by misspelling a name or using the wrong signature) the exception
> bubbles up and crashes the VM.
>
> Perhaps this could be reworked to remove the bool cleanly, but let's 
> go back to open.01 and move that cleanup to a follow-up.
>
> /Claes
>
Hi Claes,

I do have a concern that this will be a behavioral change for method 
resolution if Object::registerNatives is removed.  For example,

public class RegisterNatives {
   interface I { default public void registerNatives() { 
System.out.println("I"); } }
   static class A implements I { }
   public static void main(String... args) {
     A varA = new A();
     varA.registerNatives();
   }

Currently class A finds registerNatives in its superclass Object and the 
test receives the following:

    Exception in thread "main" java.lang.IllegalAccessError: class
    RegisterNatives tried to access private method 'void
    java.lang.Object.registerNatives()' (RegisterNatives is in unnamed
    module of loader 'app'; java.lang.Object is in module java.base of
    loader 'bootstrap')
             at RegisterNatives.main(RegisterNatives.java:6)

With your change interface I's registerNatives default method is invoked 
successfully.  I don't think this is a major backward compatibilty issue 
but we should have someone from core-libs okay the removal of the method 
from Object before committing.  In addition, can you add this test as 
part of your change?  I think it would be okay to put it in 
open/test/hotspot/jtreg/runtime/8024804 which contains an existing 
registerNatives test.

Otherwise I think .01 from the Hotspot side looks good.  Only one minor 
comment:
method.cpp
- line #426 and 427:  Since you are in this code can your change to 
resourceMark(THREAD)?

Thanks,
Lois