[foreign-jextract] RFR 8236434: Initial jextract API implementation

[Maurizio Cimadamore]

On 20/12/2019 16:15, Jorn Vernee wrote:
> Hi,
>
> Some files seem to be missing from the webrev. I only see Declaration 
> in the exported package, and when building it complains about missing 
> types (e.g. Position, Type).

Whoops - seems like 3 files were not `hg added` - attempt no. 2:

http://cr.openjdk.java.net/~mcimadamore/panama/8236434_v2

Maurizio

>
> Jorn
>
> On 20/12/2019 16:25, Maurizio Cimadamore wrote:
>> Hi,
>> here's the initial webrev for the jextract API:
>>
>> http://cr.openjdk.java.net/~mcimadamore/panama/8236434/
>>
>> And here's a link to the javadoc for said API:
>>
>> http://cr.openjdk.java.net/~mcimadamore/panama/jextract_javadoc
>>
>> Summary:
>>
>> * most of the configuration changes come from the "foreign" branch - 
>> that is, when building the new "foreign-jextract" branch you will 
>> need to specify an LLVM install (e.g. --with-libclang); I've removed 
>> few things that seemed to be unused, but most of the stuff is really 
>> the same - in principle I could have done w/o - but then it's really 
>> hard to use and test the API.
>>
>> * In the implementation code, you will find a Java port of libclang - 
>> this port has been fully written using the stuff in the foreign-abi 
>> branch (hence, method handles and var handles). The lowest layer of 
>> this API is contained in the 'libclang' folder and has been 
>> autogenerated for the most part. In other words, there's not a single 
>> line of JNI code in here.
>>
>> * It's interesting to note how - despite the many native calls in 
>> used in this port, only _one_ required breaking into privileged mode, 
>> and into ForeignUnsafe. I think that's pretty good!
>>
>> * I've paid extra attention when using layout constants - more 
>> specifically, since libclang already tries to be portable and to 
>> define things so that they have same sizes on all platforms (e.g. a 
>> long in Linux becomes a 'long long' in Windows), I've defined a bunch 
>> of size-specific ABI layout constants in ClangLayouts, and then used 
>> these everywhere in the library port. In the library implementation 
>> there are few places where we need to use real ABI-dependent layouts 
>> (when creating a Type object from a clang type), so you'll see some 
>> uses of another set of constants defined inside LayoutUtils. 
>> Hopefully, all this gymnastic should result in something that works 
>> across all ABIs.
>>
>> * I've added a very simple smoke test - I know we need to do more 
>> here, but I think it's better to start somewhere. Besides, this test 
>> should provide a useful basis to, eventually, build a more general 
>> framework to validate the result of the jextract API parsing.
>>
>> * There's no minimal jextract as of yet - since this changeset is 
>> already very big, I think it's better to first push the API, and then 
>> review the extractor code separately.
>>
>> Cheers
>> Maurizio
>>