[foreign-memaccess+abi] RFR: 8275584: Incorrect stack spilling in CallArranger on MacOS/AArch64 [v2]

[Jorn Vernee]

On Mon, 24 Oct 2022 13:57:31 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> Nick Gasson has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Remove sign-extension XXX
>
> src/java.base/share/classes/jdk/internal/foreign/abi/aarch64/CallArranger.java line 290:
> 
>> 288:                 long copy = Math.min(layout.byteSize() - offset, STACK_SLOT_SIZE);
>> 289:                 VMStorage storage =
>> 290:                     storageCalculator.stackAlloc(copy, layout.byteAlignment(), false);
> 
> Ok. So it looks like only HFAs are 'packed', and other struck follow the classic approach of passing everything in stack slot sized chunks :/

I think maybe passing `layout.byteAlignment` here is a little misleading, as it is unconditionally overwritten to `STACK_SLOT_SIZE` in `stackAlloc` any ways.

I know that's a change I made, but I think it might be better to just use `STACK_SLOT_SIZE` as alignment here, and then I don't think the extra `subSlotPacking` parameter is needed either.

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PR: https://git.openjdk.org/panama-foreign/pull/746