[llvm] [llvm-objdump] Optimize live element tracking (PR #158763)

[James Henderson via llvm-commits]

https://github.com/jh7370 commented:

Interesting idea. Can you give some example performance numbers with and without this change, please? Both memory consumption and duration would be good, if possible.

One minor point: you seem to have added a _lot_ of comments. Could I ask your motivation for doing so?

https://github.com/llvm/llvm-project/pull/158763