RFR: 8271820: Implementation of JEP 416: Reimplement Core Reflection with Method Handle [v9]

Mandy Chung mchung at openjdk.java.net
Wed Sep 22 16:18:45 UTC 2021

> This reimplements core reflection with method handles.
> For `Constructor::newInstance` and `Method::invoke`, the new implementation uses `MethodHandle`.  For `Field` accessor, the new implementation uses `VarHandle`.    For the first few invocations of one of these reflective methods on a specific reflective object we invoke the corresponding method handle directly. After that we spin a dynamic bytecode stub defined in a hidden class which loads the target `MethodHandle` or `VarHandle` from its class data as a dynamically computed constant. Loading the method handle from a constant allows JIT to inline the method-handle invocation in order to achieve good performance.
> The VM's native reflection methods are needed during early startup, before the method-handle mechanism is initialized. That happens soon after System::initPhase1 and before System::initPhase2, after which we switch to using method handles exclusively.
> The core reflection and method handle implementation are updated to handle chained caller-sensitive method calls [1] properly. A caller-sensitive method can define with a caller-sensitive adapter method that will take an additional caller class parameter and the adapter method will be annotated with `@CallerSensitiveAdapter` for better auditing.   See the detailed description from [2].
> Ran tier1-tier8 tests.   
> [1] https://bugs.openjdk.java.net/browse/JDK-8013527
> [2] https://bugs.openjdk.java.net/browse/JDK-8271820?focusedCommentId=14439430&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14439430

Mandy Chung has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 27 commits:

 - Make MethodAccessor non-volatile.  Remove MHInvoker/VHInvoker.
 - Merge
 - minor cleanup and more test case.
 - Rename InvokerBuilder to ReflectionInvokerBuilder
 - Fix NativeAccessor.c build issue for the renamed classes
 - Shorten the class name
 - Rename the accessor classes to make it explicit for method handles
 - Add a new test for testing methods whose parameter types and return type not visible to the caller
 - Move the handling of native accessor to the factory method for method/constructor accessor
 - DirectConstructorAccessorImpl should take the MHInvoker parameter
 - ... and 17 more: https://git.openjdk.java.net/jdk/compare/161fdb4a...1e68d004


Changes: https://git.openjdk.java.net/jdk/pull/5027/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5027&range=08
  Stats: 6529 lines in 75 files changed: 5990 ins; 327 del; 212 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5027.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5027/head:pull/5027

PR: https://git.openjdk.java.net/jdk/pull/5027

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