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

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> > > If this is causing a lot of issues can we possibly revert it while the fixes make their way through review, and then re-merge it with the fixes?
> > 
> > 
> > @efriedma-quic @nikic I am ok to just add a ubsan check in clang 21. Then we can reland this patch in llvm 22/23.
> 
> I'm probably missing something, but don't we already have a ubsan check for this for a long time? https://clang.godbolt.org/z/vGr7qYYjr

We have a check for pointer arithmetic, but not for member access.


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