[foreign-abi] RFR 8228486: Add ABI-specific layout constants

[Maurizio Cimadamore]

On 23/07/2019 14:20, Jorn Vernee wrote:
> Also, why aren't annotations exposed at the MemoryLayout level?

I wanted to experiment if we could get away w/o exposing them in the API 
- but having them internally as a more stable basis for implementing 
things like Layout names.

I'd like first to get a sense about how people will be using 
annotations. Layout names are useful and referenced by the 'path' API; 
general annotations don't have that kind of visibility in the API, so 
there's a chance they are just for us/jextract.

Maurizio

>
> Jorn
>
> On 2019-07-23 15:07, Jorn Vernee wrote:
>> The tests pass on Windows. Overall the patch looks good
>>
>> - in TestUpcall you seem to be using the SysV.C_POINTER constant
>> instead of the magic one.
>>
>> - Do we need to distinguish between POINTER and INTEGER class?
>> Shouldn't this just be about in which register it's passed? It looks
>> like the isPointer predicate is only used in the tests in order to
>> construct dummy arguments, is there another way around this? (e.g.
>> checking that the carrier is a MemoryAddress).
>>
>> Some things that I can look into:
>>
>> * We can mark vararg arguments with a layout annotation on Windows to
>> be able to support vargargs on Windows as well.
>>
>> * I think some of the code in Window's CallingSequenceBuilderImpl
>> could be removed at this point (e.g. the x87 stuff), since it's not
>> supported by the Windows C ABI any ways.
>>
>> Jorn
>>
>> On 2019-07-22 19:23, Maurizio Cimadamore wrote:
>>> Hi,
>>> the recent push for JDK-8228447, as expected, broke the foreign-abi
>>> branch, since that branch depended on the ValueLayout::isIntegral
>>> accessor.
>>>
>>> This patch replaces that logic with the custom layout annotation logic
>>> discussed in [1]:
>>>
>>> http://cr.openjdk.java.net/~mcimadamore/panama/8228486/
>>>
>>> This patch makes the following changes:
>>>
>>> * introduces three set of annotated layout constants, one for 
>>> supported ABI
>>> * the annotations point directly at the ABI-specific argument classes
>>> * I've consolidated ArgumentClass a bit, so that now there's a common,
>>> ABI-agnostic super-interface with some general predicates
>>> * AddressLayout has been removed (we can just look for 
>>> argumentClass::isPointer)
>>> * the tests have been tweaked to use the new ABI-specific constants;
>>> since the test has to work across platforms, all ABI test use a new
>>> interface which imports the 'right' set of constants
>>>
>>> While the patch might be a bit raw (I've only tested on Linux x64), I
>>> like where this is going.
>>>
>>> Maurizio