[jdk17] RFR: 8269240: java/foreign/stackwalk/TestAsyncStackWalk.java test failed with concurrent GC [v4]

[David Holmes]

On Fri, 16 Jul 2021 14:38:35 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> This patch rewrites the prologue and epilogue of panama upcalls, in order to fix the test failure from the title.
>> 
>> Previously, we did a call to potentially attach the current thread to the VM, and then afterwards did the same suspend and stack reguard checks that we do on the back-edge of a native downcall. Then, on the back edge of the upcall we did another conditional call to detach the thread.
>> 
>> The suspend and reguard checks on the front-edge are incorrect, so I've changed the 2 calls to mimic what is done by JavaCallWrapper instead (with attach and detach included), and removed the old suspend and stack reguard checks.
>> 
>> FWIW, this removes the JavaFrameAnchor save/restore MacroAssembler code. This is now written in C++. Also, MacroAssembler code was added to save/restore the result of the upcall around the call on the back-edge, which was previously missing. Since the new code allocates a handle block as well, I've added handling for those oops to frame & OptimizedUpcallBlob.
>> 
>> Testing: local running of `jdk_foreign` on Windows and Linux (WSL). Tier 1-3
>
> Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Address more review comments

Updates look good.

Thanks,
David

src/hotspot/share/runtime/thread.hpp line 1427:

> 1425:   static inline JavaThread* current();
> 1426:   // Returns the current thread as a JavaThread, or NULL if not attached
> 1427:   static inline JavaThread* current_or_null();

I hadn't intended to suggest the introduction of this method, but I see now how my comment led to it. It is fine.

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Marked as reviewed by dholmes (Reviewer).

PR: https://git.openjdk.java.net/jdk17/pull/149