[foreign-memaccess+abi] RFR: 8255903: Enable multi-register return values for native invokers [v3]

[Maurizio Cimadamore]

On Wed, 27 Oct 2021 10:10:50 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fixup all platform stubs
>
> src/jdk.incubator.foreign/share/classes/jdk/incubator/foreign/FunctionDescriptor.java line 126:
> 
>> 124:      * @return the new function descriptor.
>> 125:      */
>> 126:     public FunctionDescriptor withAppendedArgumentLayouts(MemoryLayout... addedLayouts) {
> 
> I think these should just be called appendArgumentLayouts/insertArgumentLayouts - or, appendArguments/insertArguments - no need for all this verbosity (but not related to your patch).

This method should be overridden in the variadic function case and throw UOE (like its siblings).

> src/jdk.incubator.foreign/share/classes/jdk/internal/foreign/abi/CallingSequenceBuilder.java line 134:
> 
>> 132:     private long computeImrSize() {
>> 133:         return outputBindings.stream()
>> 134:                 .filter(Binding.Move.class ::isInstance)
> 
> extra space here before `::`

These are all nice stream calls - but I note that isIMR, computeIMRsize all need to to a pass on the output bindings. So the code is higher level, but we do an extra pass on the bindings. That said, we pay for it at MH creation, so I guess you considered this and decided we can live with this (I agree).

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PR: https://git.openjdk.java.net/panama-foreign/pull/603