trivial fix for PR20314

Make sure that the AddrInst is an Instruction.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213197 91177308-0d34-0410-b5e6-96231b3b80d8
Fix a typo in the inalloca description

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213200 91177308-0d34-0410-b5e6-96231b3b80d8