Why doesn't AMD just write a CUDA translation layer? Yeah, it's a bit difficult to say "just", but they're a pretty big company. It's not like one guy doing it in a basement.

Does Nvidia have patents on CUDA? They're probably invalid in China which explains why China can do this and AMD can't.

They did...HIPIFY translates from CUDA to HIP (ROCm)

https://rocm.docs.amd.com/projects/HIPIFY/en/latest/index.ht...