[clang] [llvm] [clang] Integrate LLVMABI for function call ABI lowering (PR #194460)

[Nikita Popov via cfe-commits]

nikic wrote:

> Should also add an extra run line with `-fexperimental-abi-lowering` to some bpf abi tests. I think bpf-abiinfo.c, bpf-struct-argument.c, bpf-union-argument.c would be good.

This is still open.

https://github.com/llvm/llvm-project/pull/194460