[clang] [RISCV] Handle empty structs/unions passing in C++ (PR #97315)

[Sudharsan Veeravalli via cfe-commits]

svs-quic wrote:

> Thanks @efriedma-quic. I tried adding a test case for it locally and see that the code produced is different for llvm and gcc: https://godbolt.org/z/vdhGbvj6W
> 
> Test case:
> 
> ```
> struct s12 {int x[0];};
> struct s12 test_s12(struct s12 a) {
>   return a;
> }
> ```
> 
> For llvm this is an empty record of size zero and so it ignores it where as gcc loads 0 into a0. Do we handle this case similar to what gcc does? Or do I add a fixme for now?
> 
> @topperc @asb

What about the case I have mentioned in https://godbolt.org/z/vdhGbvj6W ?

Having a check for both Size==0 and LangOpts.CPlusPlus handles this as well.


https://github.com/llvm/llvm-project/pull/97315