RFR: 8303409: Add Windows AArch64 ABI support to the Foreign Function & Memory API

[Maurizio Cimadamore]

On Mon, 27 Feb 2023 17:04:28 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. The Windows ARM64 ABI conventions are documented at https://learn.microsoft.com/en-us/cpp/build/arm64-windows-abi-conventions
> 
> For details about the Foreign Function & Memory API, see JEP 434 at https://openjdk.org/jeps/434
> 
> This change is a cherry pick of https://github.com/openjdk/panama-foreign/commit/d379ca1c and https://github.com/openjdk/panama-foreign/commit/08225e4f from https://github.com/openjdk/panama-foreign/pull/754 and includes an additional commit that introduces a VaList implementation for Windows on AArch64.

Many thanks for looking into this port!

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PR: https://git.openjdk.org/jdk/pull/12773