[llvm] [RemoveDIs] Account for DPVAssigns in isIdenticalToWhenDefined (PR #82257)

[Orlando Cazalet-Hyams via llvm-commits]

OCHyams wrote:

Thanks @rupprecht 

> Is that known/expected?

It wasn't, but having a look around I think I understand why it started here and has been since fixed.

This patch added `AddressExpression` to a comparison. `AddressExpression` isn't always used by this class (it's only used when the  "kind" is `LocationType::Assign`), and it looks like [one of the ctors](https://github.com/OCHyams/llvm-project/blob/b867a2c052637d9768c7c608f6de9ad19cfab8a1/llvm/lib/IR/DebugProgramInstruction.cpp#L47) for the class doesn't initialize it.

#83242 changes `AddressExpression` to a new type which wraps a pointer that is member initialized to nullptr.

So I imagine the uninitialized garbage in `AddressExpression` when that one ctor was used was throwing off the comparision, and it was stealth fixed because `AddressExpression` is now always initialized properly.

https://github.com/llvm/llvm-project/pull/82257