RFR: 8303040: linux PPC64le: Implementation of Foreign Function & Memory API (Preview) [v3]

[Martin Doerr]

On Wed, 1 Mar 2023 06:26:20 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> src/java.base/share/classes/jdk/internal/foreign/abi/ppc64/CallArranger.java line 293:
>> 
>>> 291:                 } else {
>>> 292:                     overlappingReg = new VMStorage(StorageType.STACK_AND_FLOAT,
>>> 293:                                                    (short) STACK_SLOT_SIZE, (int) stackOffset - 4);
>> 
>> I think you could remove the mixed VMStorage types here relatively easily by returning a `VMStorage[][]`, where each element is a single element array, but then for the `needOverlapping` case add another element to the array for the extra store (instead of replacing the existing one).
>> 
>> Then when unboxing a `STRUCT_HFA`,  `dup` the result of the `bufferLoad` and then do 2 `vmStore`s (one for each element).
>> 
>> For boxing, you could just ignore the extra storage, and just `vmLoad` the first one (or, whichever one you like :))
>
> Thanks! I need to find extra time for this. Sounds like a good idea and I may be able to get rid of some nasty code.

Done by https://github.com/openjdk/jdk/pull/12708/commits/98e242c24c07ea977b7709b9f8d0c10ce87e84c0 (using a record instead of a `VMStorage[][]` because I think this is better readable). Note that it's a bit more complicated. I couldn't use your `dup` trick, because I need to put the value into a GP reg and one half of it to a FP reg. The Panama code doesn't support that (IllegalArgumentException: Invalid operand type: interface java.lang.foreign.MemorySegment. float expected).

-------------

PR: https://git.openjdk.org/jdk/pull/12708