In one case, we were handling out of bounds, but not undef indices. In the other, we were handling undef (with the comment making the analogy to out of bounds), but not out of bounds. Be consistent and treat both undef and constant out of bounds indices as producing undefined results.
As a side effect, this also protects instcombine from having to handle large constant indices as we always simplify first.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@321575 91177308-0d34-0410-b5e6-96231b3b80d8
Philip Reames