vector and extraneous loop over it, 2) not delete globals used by
phis/selects etc which could actually be useful. This fixes PR3321.
Many thanks to Duncan for narrowing this down.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62201 91177308-0d34-0410-b5e6-96231b3b80d8
