I don't have a test case for these, but there is a test case for D62266
where, even after all the constant-folding patches, we still end up
with endless combine loop. Which makes sense, since we don't constant
fold for opaque constants.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@362156 91177308-0d34-0410-b5e6-96231b3b80d8