[llvm] [DSE] Split memory intrinsics if they are dead in the middle (PR #75478)

[Nabeel Omer via llvm-commits]

omern1 wrote:

Sorry for the force push, diff from pre-committed tests is here: https://github.com/llvm/llvm-project/pull/75478/commits/6f26953df74bb8a9c0d6d760870882af7db43670

https://github.com/llvm/llvm-project/pull/75478