[llvm] [LLVM] Improve the DemandedBits Analysis (PR #148880)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

Kindly note that we only have a squash-and-merge. As a result:

1. Your commit message should be filled into the PR, including the title. The PR's title and body will be used as the commit message, and the text in your commit will be discarded when landing.
2. Kindly add additional changes as separate commits, and avoid force-pushing except when a rebase is required.

https://github.com/llvm/llvm-project/pull/148880