RFR: 8271820: Implementation of JEP 416: Reimplement Core Reflection with Method Handle [v10]
Mandy Chung
mchung at openjdk.java.net
Wed Oct 6 19:14:26 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 30 commits:
- Add java.lang.reflect and jdk.internal.reflect to trusted non-static final fields packages
- Merge
- ensure class initialized before field acces
- 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
- ... and 20 more: https://git.openjdk.java.net/jdk/compare/83b22192...9c28df4c
-------------
Changes: https://git.openjdk.java.net/jdk/pull/5027/files
Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5027&range=09
Stats: 6411 lines in 78 files changed: 5896 ins; 317 del; 198 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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