RFR: 8227745: Enable Escape Analysis for Better Performance in the Presence of JVMTI Agents [v4]

[Richard Reingruber]

> Hi,
> 
> this is the continuation of the review of the implementation for:
> 
> https://bugs.openjdk.java.net/browse/JDK-8227745
> https://bugs.openjdk.java.net/browse/JDK-8233915
> 
> It allows for JIT optimizations based on escape analysis even if JVMTI agents acquire capabilities to access references
> to objects that are subject to such optimizations, e.g. scalar replacement. The implementation reverts such
> optimizations just before access very much as when switching from JIT compiled execution to the interpreter, aka
> "deoptimization".  Webrev.8 was the last one before before the transition to Git/Github:
> 
> http://cr.openjdk.java.net/~rrich/webrevs/8227745/webrev.8/
> 
> Thanks, Richard.

Richard Reingruber has updated the pull request incrementally with five additional commits since the last revision:

 - EATests.java: bugfix to prevent ObjectCollectedException
 - Better encapsulation of JvmtiDeferredUpdates. Moved jvmtiDeferredLocalVariableSet to jvmtiDeferredUpdates.hpp
 - EscapeBarrier: moved method comments.
 - Shuffled parameters of EscapeBarrier constructors to better match each other
 - Moved class EscapeBarrier and class JvmtiDeferredUpdates into dedicated files.

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/119/files
  - new: https://git.openjdk.java.net/jdk/pull/119/files/5bf631ba..c33cc4e8

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=119&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=119&range=02-03

  Stats: 1385 lines in 18 files changed: 777 ins; 586 del; 22 mod
  Patch: https://git.openjdk.java.net/jdk/pull/119.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/119/head:pull/119

PR: https://git.openjdk.java.net/jdk/pull/119