RFR: 8295044: Implementation of Foreign Function and Memory API (Second Preview) [v2]

[Jorn Vernee]

On Mon, 7 Nov 2022 09:40:03 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> src/java.base/share/classes/jdk/internal/foreign/abi/x64/windows/CallArranger.java line 165:
>> 
>>> 163:                 assert forArguments : "no stack returns";
>>> 164:                 // stack
>>> 165:                 long alignment = Math.max(layout.byteAlignment(), STACK_SLOT_SIZE);
>> 
>> This is also missing part of the changes from: https://github.com/openjdk/panama-foreign/pull/728/ but other changes to the shared code are present. The `layout` parameter is not needed here. (see the changes to this file in the original PR)
>
> Actually, this patch is missing most of the stuff in PR 728. I was under the impression that, in order to fully support that, some VM changes were needed (e.g. to have better granularity in call shuffling - as per https://github.com/openjdk/panama-foreign/pull/699). As a result, this PR only contains changes to SharedUtil (to remove unused alignment functions) - but nothing else.

699 is not needed for this. 728 is a pure Java change that simply rejects layouts that don't have their natural alignment (so, it will rejects packed structs for instance, since the implementation doesn't support them on all platforms). All the other changes from 728 are here (most notably the code in AbstractLinker that checks the alignment), except the change that ignores the `layout` here and turns the code around the line above into an `assert`.

The mac stack spilling patch requires 699 though (https://github.com/openjdk/panama-foreign/pull/746). I will put that in the PR with the VM changes.

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PR: https://git.openjdk.org/jdk/pull/10872