[llvm] [LoongArch] Enable tail calls for sret functions and relax argument matching (PR #168506)

[Folkert de Vries via llvm-commits]

folkertdev wrote:

Thanks so much for this! It looks like the riscv code is very similar to loongarch, so this approach should also work there, covering all targets that `rustc` would reasonably care about for an MVP.

It might be worthwhile to also test this case https://godbolt.org/z/5evjsn1zs, which both x86_64 and aarch64 currently miscompile (their stack shuffling is incorrect, on x86_64 that overwrites the return address and segfaults).

https://github.com/llvm/llvm-project/pull/168506