[llvm] [SCEVAA] Allowing to subtract two inttoptrs with different pointer bases (PR #91453)

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csstormq wrote:

> See https://reviews.llvm.org/D104806 for why getMinusSCEV works this way. I would rather not relax the current restrictions.
> 
> What happens if you make SCEVAA explicitly PtrToInt the operands to the subtraction?

As you suggested, I have already tried the ptrtpoint pointer operands before calling getMinusSCEV(). `SCEVAAResult::alias()` returns `NoAlias` for my example. I am very glad about this result. But I'm not sure if this should always be done. Should an option be added to control whether it is turned on ?

https://github.com/llvm/llvm-project/pull/91453