[foreign-abi] RFR: 8253255: Investigate replacing ABI layout attributes with custom subtypes of ValueLayout [v2]

[Maurizio Cimadamore]

On Tue, 29 Sep 2020 11:18:55 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> Hi,
>> 
>> This patch removes ABI attributes, and replaces them with a custom ValueLayout subtype, called CValueLayout.
>> 
>> This, for one, allows us to override the describeConstable method to return a dynamic constant descriptor that will
>> load the public constant field in CLinker. This avoids getting illegal access errors when trying to resolve the
>> internal ABI attributes. The illegal access error was forcing clients, like jextract, to basically re-implement the
>> describeConstable methods for FunctionDescriptor, GroupLayout, SequenceLayout and ValueLayout in order the
>> 'cannonicalize' these constant descriptors to reference the fields.  Most of the needed changes were in the TypeClass
>> classes, which now need to map the CValueLayout.Kind into the appropriate ABI classes (though doing this was pretty
>> straight forward).  I've also added a test to make sure it is possible to resolve constant descriptors with these
>> CValueLayouts inside with a public Lookup object.  Thanks, Jorn
>
> Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add equals and hashCode mehtods to CValueLayout, and make sure CValueLayout and ValueLayout are not equal

Looks good!

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Marked as reviewed by mcimadamore (Committer).

PR: https://git.openjdk.java.net/panama-foreign/pull/358