[foreign-memaccess+abi] RFR: 8295290: Add Windows ARM64 ABI support to the Foreign Function & Memory API

[Jorn Vernee]

On Tue, 22 Nov 2022 19:01:32 GMT, Saint Wesonga <duke at openjdk.org> wrote:

> There are 2 primary differences between the Windows ARM64 ABI and the macOS/Linux ARM64 ABI: variadic floating point arguments are passed in general purpose registers on Windows (instead of the vector registers). In addition to this, up to 64 bytes of a struct being passed to a variadic function can be placed in general purpose registers. This happens regardless of the type of struct (HFA or other generic struct). This means that a struct can be split across registers and the stack when invoking a variadic function.
> 
> This change introduces tests that compute the sum of the fields of structs containing 1-4 ints, floats, and doubles to verify that each field is correctly assigned a register or stack location when invoking a variadic function (both when the struct can be passed entirely in registers as well as when the struct spills onto the stack).
> 
> For details about the Foreign Function & Memory API, see JEP 434 defined at https://openjdk.org/jeps/434
> 
> The Windows ARM64 ABI conventions are documented at https://learn.microsoft.com/en-us/cpp/build/arm64-windows-abi-conventions
> 
> This work builds on @lewurm / Bernhard's branch at https://github.com/lewurm/openjdk/commits/foreign-windows-aarch64

@swesonga I applied some fixes to test/jdk/java/foreign/TestMatrix.java [1] that were merged into this repo today. You might want to merge the latest `foreign-memaccess+abi` branch into this PR branch to get those changes as well.

[1]: https://github.com/openjdk/jdk/pull/11398

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PR: https://git.openjdk.org/panama-foreign/pull/754