[llvm] [PatternMatch] Do not accept undef elements in m_AllOnes() and friends (PR #88217)

[Nikita Popov via llvm-commits]

nikic wrote:

@dtcxzyw It will take more changes to get there, but yes, we should definitely get rid of such replaceUndefsWith calls.

https://github.com/llvm/llvm-project/pull/88217