[foreign-abi] RFR 8232628: foreign-abi usability issues

[Maurizio Cimadamore]

P.S.

The changes in DIrectSignatureShuffler are necessary to fix an exception 
(the current code is trying to call returnBindings when returnsInMemory 
is set)

Maurizio

On 22/10/2019 11:12, Maurizio Cimadamore wrote:
> Whoops - forget the link
>
> http://cr.openjdk.java.net/~mcimadamore/panama/8232628/
>
> Maurizio
>
> On 18/10/2019 18:23, Maurizio Cimadamore wrote:
>> Hi,
>> as an experiment/test I tried to write a port of libclang which uses 
>> the low level MH and VH as a backbone. I discovered few usability 
>> issues in foreign-abi, which I tried to resolve with this patch; more 
>> specifically:
>>
>> - there's no way to get the null address
>> - the null address is not stable, so it's hard to test
>>
>> For now, I've added a method to ForeignUnsafe - an alternative would 
>> be to add a NULL address constant in the MemoryAddress API, but if we 
>> do that, we need to make sure that the user can't do anything with it 
>> (which means we should probably create a NOTHING memory segment to 
>> prevent slicing).
>>
>> I'm open to experiment if there's a feeling this might be a better 
>> approach (e.g. to avoid relying on ForeignUnsafe too much).
>>
>> Maurizio
>>
>>