Hi David,


A small typo: retransformation => redefinition
-     * The redefinition may change method bodies, the constant pool and attributes.
+     * The redefinition may change method bodies, the constant pool and attributes
+     * (unless explicitly prohibited).
      * The redefinition must not add, remove or rename fields or methods, change the
-     * signatures of methods, or change inheritance.  These restrictions maybe be
-     * lifted in future versions.  The class file bytes are not checked, verified and installed
+     * signatures of methods, or change inheritance.
+     * The retransformation must not change the <code>NestHost</code> or
+     * <code>NestMembers</code> attributes.
+     * These restrictions maybe be lifted in future versions.
+     * The class file bytes are not checked, verified and installed

Otherwise, the changes look good.
No need in another webrev if the above is fixed.

Thank you for taking care about this!


On 5/16/18 23:33, David Holmes wrote:
FYI I updated the webrev with an additional change to the JDI/JDWP version - which needed updating to 11. This was done under "nestmates" as:


and the patch has now been included here. Only two files with trivial updates:



On 15/05/2018 10:52 AM, David Holmes wrote:
This review is being spread across four groups: langtools, core-libs, hotspot and serviceability. This is the specific review thread for serviceability - webrev:


See below for full details - including annotated full webrev guiding the review.

The intent is to have JEP-181 targeted and integrated by the end of this month.


The nestmates project (JEP-181) introduces new classfile attributes to identify classes and interfaces in the same nest, so that the VM can perform access control based on those attributes and so allow direct private access between nestmates without requiring javac to generate synthetic accessor methods. These access control changes also extend to core reflection and the MethodHandle.Lookup contexts.

Direct private calls between nestmates requires a more general calling context than is permitted by invokespecial, and so the JVMS is updated to allow, and javac updated to use, invokevirtual and invokeinterface for private class and interface method calls respectively. These changed semantics also extend to MethodHandle findXXX operations.

At this time we are only concerned with static nest definitions, which map to a top-level class/interface as the nest-host and all its nested types as nest-members.

Please see the JEP for further details.

JEP: https://bugs.openjdk.java.net/browse/JDK-8046171
Bug: https://bugs.openjdk.java.net/browse/JDK-8010319
CSR: https://bugs.openjdk.java.net/browse/JDK-8197445

All of the specification changes have been previously been worked out by the Valhalla Project Expert Group, and the implementation reviewed by the various contributors and discussed on the valhalla-dev mailing list.

Acknowledgments and contributions: Alex Buckley, Maurizio Cimadamore, Mandy Chung, Tobias Hartmann, Vladimir Ivanov, Karen Kinnear, Vladimir Kozlov, John Rose, Dan Smith, Serguei Spitsyn, Kumar Srinivasan

Master webrev of all changes:


Annotated master webrev index:


Performance: this is expected to be performance neutral in a general sense. Benchmarking and performance runs are about to start.

Testing Discussion:

The testing for nestmates can be broken into four main groups:

-  New tests specifically related to nestmates and currently in the runtime/Nestmates directory

- New tests to complement existing tests by adding in testcases not previously expressible.
   -  For example java/lang/invoke/SpecialInterfaceCall.java tests use of invokespecial for private interface methods and performing receiver typechecks, so we add java/lang/invoke/PrivateInterfaceCall.java to do similar tests for invokeinterface.

-  New JVM TI tests to verify the spec changes related to nest attributes.

-  Existing tests significantly affected by the nestmates changes, primarily:
    -  runtime/SelectionResolution

    In most cases the nestmate changes makes certain invocations that were illegal, legal (e.g. not requiring invokespecial to invoke private interface methods; allowing access to private members via reflection/Methodhandles that were previously not allowed).

- Existing tests incidentally affected by the nestmate changes

   This includes tests of things utilising class redefinition/retransformation to alter nested types but which unintentionally alter nest relationships (which is not permitted).

There are still a number of tests problem-listed with issues filed against them to have them adapted to work with nestmates. Some of these are intended to be addressed in the short-term, while some (such as the runtime/SelectionResolution test changes) may not eventuate.

- https://bugs.openjdk.java.net/browse/JDK-8203033
- https://bugs.openjdk.java.net/browse/JDK-8199450
- https://bugs.openjdk.java.net/browse/JDK-8196855
- https://bugs.openjdk.java.net/browse/JDK-8194857
- https://bugs.openjdk.java.net/browse/JDK-8187655

There is also further test work still to be completed (the JNI and JDI invocation tests):
- https://bugs.openjdk.java.net/browse/JDK-8191117
which will continue in parallel with the main RFR.

Pre-integration Testing:
  - General:
     - Mach5: hs/jdk tier1,2
     - Mach5: hs-nightly (tiers 1 -3)
  - Targetted
    - nashorn (for asm changes)
    - hotspot: runtime/*
    - jdk: java/lang/invoke/*
   - langtools: tools/javac

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