[llvm] [InstCombine][ValueTracking] Improve logic for shift flags. (PR #67758)

[via llvm-commits]

goldsteinn wrote:

> Please squash your commits before landing the pull request.
> 
> ```
> gh pr merge --squash --delete-branch
> ```
-1, intentionally keeping commits seperate.
> 
> Besides, you should attach `Close #67758` at the end of the commit message to let GitHub know the commit is linked with this PR. Then GitHub will close this PR automatically.
> 
+1 will do so.

> See also https://llvm.org/docs/GitHub.html#landing-your-change.



https://github.com/llvm/llvm-project/pull/67758