[llvm] [RFC][BPF] Support Jump Table (PR #133856)

[Anton Protopopov via llvm-commits]

aspsk wrote:

> I found a problem and just added another commit to fix the problem

Thanks @yonghong-song! I will test your latest changes over this weekend.

(The `tunnel` test I've fixed already, so all selftests pass now. Now need to replace hacks with normal code, and will send the patch.)

https://github.com/llvm/llvm-project/pull/133856