[llvm] [GlobalOpt] Handle operators separately when removing GV users (PR #84694)

[Anshil Gandhi via llvm-commits]

gandhi56 wrote:

> With these changes, what's the difference between cleanupPointerRootUsers and CleanupConstantGlobalUsers?

`CleanupConstantGlobalUsers` cleans up the trivial users of `GV`, whereas `cleanupPointerRootUsers` handles computation chains leading up to the pointer root `GV`. `cleanupPointerRootUsers` makes a call to `isSafeComputationToRemove` before removing the chain. 

https://github.com/llvm/llvm-project/pull/84694