[llvm] [BPF] report `Invalid usage of the XADD return value"` elegantly (PR #92742)

[Yingchi Long via llvm-commits]

inclyc wrote:

> In this case, we will have a register used in some later instructions, this does not seem to violate any IR-level constraints, so this change should be fine as far as I understand.

Actually if there are some errors generated, there are no binary files emitted at all. I suppose this will not affect end-users.

https://github.com/llvm/llvm-project/pull/92742