[llvm] [InstCombine] Simplify select using KnownBits of condition (PR #95923)

[via llvm-commits]

goldsteinn wrote:

 
> It doesn't fully avoid the regression on that test case, as many selects do have potentially affected values, but at least cuts it in half.
> 
> Do you want me to include that?
>
Unless it dramatically undermines the value of the patch, halfway is better than nothing no?


https://github.com/llvm/llvm-project/pull/95923