Make these methods const correct.

Thanks to Nick Lewycky for noticing it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187098 91177308-0d34-0410-b5e6-96231b3b80d8
Check that TD isn't NULL before dereferencing it down this path.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187099 91177308-0d34-0410-b5e6-96231b3b80d8