[llvm] [LLVM][SVE] Honour calling convention when using SVE for fixed length vectors. (PR #70847)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

I agree this sounds like the right direction to take. We probably cant get away with not supporting these argument types with fixed length SVE, and it sounds best to not change the ABI based on having the target feature and sve min vector width.

This seems to mark scalar variables as being passed in gpr registers, where as they should be the first element in a wider vector. See AArch64TargetLowering::getPreferredVectorAction for where it is overridden.

https://github.com/llvm/llvm-project/pull/70847