Handle null a bit more carefully.

Actually teach dsa about select instructions.  This doesn't affect the
graph in any way other than not setting a spurious U marker on pointer
nodes that are selected.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@20324 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed