a353e258ba
If we have a pointer AddRec, the maximum increment is 2^(pointer-index-wdith - 1) - 1. This means that if incrementing the AddRec wraps, the distance between the previously accessed location and the wrapped location is > 2^(pointer-index-wdith - 1), i.e. if the GEP for the AddRec is inbounds, this would be poison due to the object being larger than half the pointer index type space. The poison would be immediate UB when the memory access gets executed.. Similar reasoning can be applied for decrements. PR: https://github.com/llvm/llvm-project/pull/113126