[llvm] [RISCV][GISel] Fallback in LowerCall for byval arguments. (PR #119251)

[Sam Elliott via llvm-commits]

lenary wrote:

It's not clear to me the AArch64 GlobalISel byval handling code is correct anyway: https://github.com/llvm/llvm-project/issues/62138 (and, the same actually applies to SelectionDAG: https://github.com/llvm/llvm-project/issues/62137)

I think RISC-V SDAG is doing something better for byval than AArch64 SDAG (making the copies earlier), but I'm not sure anyone is quite getting byval right with GlobalISel

https://github.com/llvm/llvm-project/pull/119251