[llvm] [Attributor] New attribute to identify what byte ranges are alive for an allocation (PR #66148)

[Vidhush Singhal via llvm-commits]

vidsinghal wrote:

@shiltian, @jhuber6 , @sstefan1 it would be great if you could provide some comments on this PR.

https://github.com/llvm/llvm-project/pull/66148