[foreign-memaccess+abi] RFR: 8299730: Add trivial call linker option [v2]

[Maurizio Cimadamore]

On Tue, 24 Jan 2023 18:33:28 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Add negative trivial upcall test
>
> src/java.base/share/classes/java/lang/foreign/Linker.java line 322:
> 
>> 320:          * <p>
>> 321:          * A 'trivial' function is a function that has an extremely short running time
>> 322:          * in all cases (similar to calling an empty function), and does not call back into Java.
> 
> Suggestion:
> 
>          * in all cases (similar to calling an empty function), and does not call back into Java (e.g. using an upcall stub).

We should probably mention `getpid` somewhere as the poster child for trivial calls.

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PR: https://git.openjdk.org/panama-foreign/pull/771