RFR: 8227745: Enable Escape Analysis for Better Performance in the Presence of JVMTI Agents [v7]

[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:

 - Factorized fragment out of EscapeBarrier::deoptimize_objects_internal into new method in compiledVFrame.
 - More smaller changes proposed by Serguei.
 - jvmtiDeferredUpdates.hpp: remove forward declarations.
 - jvmtiDeferredLocalVariable: move member variables to the beginning of the class definition.
 - jvmtiDeferredUpdates.hpp: add/remove empty lines and improve indentation.

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/119/files
  - new: https://git.openjdk.java.net/jdk/pull/119/files/1c586cfb..03f751eb

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=119&range=06
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=119&range=05-06

  Stats: 183 lines in 7 files changed: 93 ins; 66 del; 24 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