RFR: 8271820: Implementation of JEP 416: Reimplement Core Reflection with Method Handle [v8]

[Mandy Chung]

> 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 incrementally with one additional commit since the last revision:

  minor cleanup and more test case.

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5027/files
  - new: https://git.openjdk.java.net/jdk/pull/5027/files/68bb9efe..32e7f340

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5027&range=07
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5027&range=06-07

  Stats: 56 lines in 8 files changed: 33 ins; 0 del; 23 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