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

[Serguei Spitsyn]

On Wed, 7 Oct 2020 17:52:27 GMT, Richard Reingruber <rrich at openjdk.org> wrote:

>> 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.

Richard,
Thank you for the formatting and refactoring changes.
The fix looks good to me.

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Marked as reviewed by sspitsyn (Reviewer).

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