[clang] [Clang][ABI] Classify floating-point matrix types as homogeneous aggregates (PR #222429)

[Peter Smith via cfe-commits]

https://github.com/smithp35 commented:

I'm not familiar with the clang code or the Matrix Types https://clang.llvm.org/docs/MatrixTypes.html so I had best let those more familiar with that to comment on the specifics.

I assume these map to an equivalent of an array of the underlying type. From there I've checked that against the AAPCS https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst#homogeneous-aggregates and the test case. The code-generated looks OK to me. I've made a couple of small suggestions.

https://github.com/llvm/llvm-project/pull/222429