[llvm] [InstCombine] Fold ((X + AddC) & Mask) ^ Mask to (~AddC - X) & Mask (PR #174278)

[Nikita Popov via llvm-commits]

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nikic wrote:

```suggestion
    Value *NotC = Builder.CreateNot(AddC);
```
To save us some work when this method is removed...

https://github.com/llvm/llvm-project/pull/174278