RFR: 8227745: Enable Escape Analysis for Better Performance in the Presence of JVMTI Agents [v9]

[Vladimir Kozlov]

On Thu, 8 Oct 2020 16:55:31 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 with a new target base due to a merge or a rebase. The pull request now
> contains 19 commits:
>  - Merge branch 'master' into JDK-8227745
>  - Merge branch 'master' into JDK-8227745
>  - 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.
>  - Merge branch 'master' into JDK-8227745
>  - Merge branch 'master' into JDK-8227745
>  - Make parameter current_thread of JvmtiEnvBase::check_top_frame() a JavaThread* again.
>    
>    With Asynchronous handshakes the type was changed from JavaThread* to Thread*
>    but this is not necessary as check_top_frame() is not executed during a handshake
>    / safepoint (robehn confirmed).
>  - ... and 9 more: https://git.openjdk.java.net/jdk/compare/d036dca0...d463b4f3

Compiler changes seems fine.

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Marked as reviewed by kvn (Reviewer).

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