[llvm] [InstSimplify] Fold `getelementptr inbounds null, idx -> null` (PR #130742)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

We may need a policy to reserve enough time for users to fix UB in existing code before making more aggressive optimizations. We can land a corresponding ubsan check first. Then we land the optimization patch set in the next or next two releases.


https://github.com/llvm/llvm-project/pull/130742