- LHS exclude RHS - LHS intersect RHS (LHS successors will keeped) - RHS exclude LHS The complexity is N+M, where N is size of LHS M is size of RHS. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159201 91177308-0d34-0410-b5e6-96231b3b80d8