[llvm] [DSE] Update dereferenceable attributes when adjusting memintrinsic ptr (PR #125073)

[Nikita Popov via llvm-commits]

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@@ -563,6 +563,22 @@ static void shortenAssignment(Instruction *Inst, Value *OriginalDest,
   for_each(LinkedDVRAssigns, InsertAssignForOverlap);
 }
 
+// Helper to trim or drop any dereferencable/dereferencable_or_null attributes
----------------
nikic wrote:

```suggestion
// Helper to trim or drop any dereferenceable/dereferenceable_or_null attributes
```

https://github.com/llvm/llvm-project/pull/125073