RFR: 8283689: Update the foreign linker VM implementation [v16]

[openjdk-notifier[bot]]

On Thu, 12 May 2022 16:01:17 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> Hi,
>> 
>> This PR updates the VM implementation of the foreign linker, by bringing over commits from the panama-foreign repo.
>> 
>> This is split off from the main JEP integration for 19, since we have limited resources to handle this. As such, this PR might fall over to 20, but it would be nice if we could get it into 19.
>> 
>> I've written up an overview of the Linker architecture here: http://cr.openjdk.java.net/~jvernee/docs/FL_Overview.html it might be useful to read that first.
>> 
>> This patch moves from the "legacy" implementation, to what is currently implemented in the panama-foreign repo, except for replacing the use of method handle combinators with ASM. That will come in a later path. To recap. This PR contains the following changes:
>> 
>> 1. VM stubs for downcalls are now generated up front, instead of lazily by C2 [1].
>> 2. the VM support for upcalls/downcalls now support all possible call shapes. And VM stubs and Java code implementing the buffered invocation strategy has been removed  [2], [3], [4], [5].
>> 3. The existing C2 intrinsification support for the `linkToNative` method handle linker was no longer needed and has been removed [6] (support might be re-added in another form later).
>> 4. Some other cleanups, such as: OptimizedEntryBlob (for upcalls) now implements RuntimeBlob directly. Binding to java classes has been rewritten to use javaClasses.h/cpp (this wasn't previously possible due to these java classes being in an incubator module) [7], [8], [9].
>> 
>> While the patch mostly consists of VM changes, there are also some Java changes to support (2).
>> 
>> The original commit structure has been mostly retained, so it might be useful to look at a specific commit, or the corresponding patch in the [panama-foreign](https://github.com/openjdk/panama-foreign/pulls?q=is%3Apr) repo as well. I've also left some inline comments to explain some of the changes, which will hopefully make reviewing easier.
>> 
>> Testing: Tier1-4
>> 
>> Thanks,
>> Jorn
>> 
>> [1]: https://github.com/openjdk/jdk/pull/7959/commits/048b88156814579dca1f70742061ad24942fd358
>> [2]: https://github.com/openjdk/jdk/pull/7959/commits/2fbbef472b4c2b4fee5ede2f18cd81ab61e88f49
>> [3]: https://github.com/openjdk/jdk/pull/7959/commits/8a957a4ed9cc8d1f708ea8777212eb51ab403dc3
>> [4]: https://github.com/openjdk/jdk/pull/7959/commits/35ba1d964f1de4a77345dc58debe0565db4b0ff3
>> [5]: https://github.com/openjdk/jdk/pull/7959/commits/4e72aae22920300c5ffa16fed805b62ed9092120
>> [6]: https://github.com/openjdk/jdk/pull/7959/commits/08e22e1b468c5c8f0cfd7135c72849944068aa7a
>> [7]: https://github.com/openjdk/jdk/pull/7959/commits/451cd9edf54016c182dab21a8b26bd8b609fc062
>> [8]: https://github.com/openjdk/jdk/pull/7959/commits/4c851d2795afafec3a3ab17f4142ee098692068f
>> [9]: https://github.com/openjdk/jdk/pull/7959/commits/d025377799424f31512dca2ffe95491cd5ae22f9
>
> Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Undo spurious changes.

The dependent pull request has now been integrated, and the target branch of this pull request has been updated. This means that changes from the dependent pull request can start to show up as belonging to this pull request, which may be confusing for reviewers. To remedy this situation, simply merge the latest changes from the new target branch into this pull request by running commands similar to these in the local repository for your personal fork:


git checkout JEP-19-VM-IMPL2
git fetch https://git.openjdk.java.net/jdk master
git merge FETCH_HEAD
# if there are conflicts, follow the instructions given by git merge
git commit -m "Merge master"
git push

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PR: https://git.openjdk.java.net/jdk/pull/7959