Comment 48 for bug 313202

Attached is my first full implementation of struct pass by value on ARM64 backend. I have implemented everything in the ABI for passing arguments, except for scalable types, vector types, half float, quad floats, and quad integers, which are not supported by SBCL. However, the test framework has not been updated, and I will only consider this milestone "done" when the tests cover all of AAPCS64's cases.

Returning by value is not implemented yet.