RFR: 8227745: Enable Escape Analysis for Better Performance in the Presence of JVMTI Agents [v3]
Richard Reingruber
rrich at openjdk.java.net
Thu Sep 24 16:59:03 UTC 2020
> 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 incremental
webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional
commits since the last revision:
- Merge branch 'master' into JDK-8227745
- Changes based on dholmes' feedback.
EscapeBarrier::sync_and_suspend_all():
- Set suspend flags before handshake because then the setting will be visible
after leaving the _thread_blocked state in JavaThread::wait_for_object_deoptimization()
JavaThread::wait_for_object_deoptimization()
- Reuse SpinYield instead of new custom spinning code.
- Do safepoint check after the loop. This is possible because the
set_obj_deopt_flag is done before the handshake.
- Don't set_suspend_equivalent() anymore for more simplicity. It's just an
optimization (that won't pay off here).
Added/updated source code comments.
Additional smaller enhancements.
- 8227745, 8233915: Enable Escape Analysis for Better Performance in the Presence of JVMTI Agents
-------------
Changes:
- all: https://git.openjdk.java.net/jdk/pull/119/files
- new: https://git.openjdk.java.net/jdk/pull/119/files/18dd54b4..5bf631ba
Webrevs:
- full: https://webrevs.openjdk.java.net/?repo=jdk&pr=119&range=02
- incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=119&range=01-02
Stats: 26592 lines in 830 files changed: 13744 ins; 9718 del; 3130 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
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