[foreign-memaccess+abi] RFR: 8302346: Lift upcall sharing mechanism to AbstractLinker [v2]

[Maurizio Cimadamore]

On Fri, 17 Feb 2023 20:54:29 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> Lift the upcall sharing mechanism to AbstractLinker, where it can live next to the similar mechanism for down calls. This also allows the fallback linker to use this mechanism.
>> 
>> Instead of an upcall stub, AbstractLinker::arrangeDowncall now return an UpcallStubFactory, which is a callback accepting a target MethodHandle and Arena, which are then used to construct the actual upcall stub.
>> 
>> Perhaps the trickiest part of this patch is that we have to simulate the effects of `SharedUtils::adaptUpcallForIMR` on the target method type. I've added a new method in SharedUtils, called `computeUpcallIMRType` for that, which mimics the shape of the `adaptUpcallForIMR` method.
>> 
>> Since the shape of most of the arrangeUpcall methods was very similar, I factored them out into a helper method in SharedUtils as well.
>
> Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:
> 
>   use fake MH for adaptation

Nice simplification!

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Marked as reviewed by mcimadamore (Committer).

PR: https://git.openjdk.org/panama-foreign/pull/791