[llvm] [BPF] Support Jump Table (PR #149715)

[via llvm-commits]

yonghong-song wrote:

Just uploaded a new version: (1). use 4 bytes for jump table element size instead of 8. (2). Fixed Example 2 (single jump label case). (3). Also push computed goto target tables into jump table infrastructure to make eventual symbol generation the same.

The current jump table element holds the value representing offset from the beginning of the section. I tried to represent the offset from the gotox but it looks hard since we do not have a marking for gotox which corresponding to which JTI. Also it looks like gotox may represent more than one jump table. Some data flow analysis will be needed to achieve this. I have not explored this yet.

https://github.com/llvm/llvm-project/pull/149715