[llvm] [loop-idiom] Forget outer loop scev when loop-idiom introduces memset… (PR #150916)

[Sushant Gokhale via llvm-commits]

sushgokh wrote:

> I think it would make more sense to adjust the loop properties calculation to not consider a non-volatile memset to be a side effect (in the sense of the forward progress guarantee).
> 
> The way to generalize that would probably to say that the call can't write inaccessible memory, assuming we always model synchronization as accessing inaccessible memory. But conservatively just special casing memory intrinsics would be ok.

Are the side effects limited to writing to inaccessible memory?

https://github.com/llvm/llvm-project/pull/150916