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

[Anton Protopopov via llvm-commits]

aspsk wrote:

Here's the kernel side which works with this LLVM: https://lore.kernel.org/bpf/20250615085943.3871208-1-a.s.protopopov@gmail.com/ 

The following selftests contain indirect jumps (and pass):

    * cgroup_tcp_skb, cls_redirect, bpf_tcp_ca,
    * bpf_iter_setsockopt, tc_change_tail, net_timestamping,
    * user_ringbuf, tcp_hdr_options, tunnel, exceptions,
    * tcpbpf_user, tcp_custom_syncookie
    
A new selftest `bpf_goto_x` specifically tries to test different scenarios.

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