[langtools] RFR (L): 8010319: Implementation of JEP 181: Nest-Based Access Control

[David Holmes]

This review is being spread across four groups: langtools, core-libs, 
hotspot and serviceability. This is the specific review thread for 
langtools - webrev:

http://cr.openjdk.java.net/~dholmes/8010319-JEP181/webrev.langtools.v1/

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.

Thanks,
David
-----

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:

http://cr.openjdk.java.net/~dholmes/8010319-JEP181/webrev.full.v1/

Annotated master webrev index:

http://cr.openjdk.java.net/~dholmes/8010319-JEP181/jep181-webrev.html

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/*
               serviceability/*
               compiler/*
               vmTestbase/*
    - jdk: java/lang/invoke/*
           java/lang/reflect/*
           java/lang/instrument/*
           java/lang/Class/*
           java/lang/management/*
   - langtools: tools/javac
                tools/javap