Silence more static analyzer warnings.

Add in definedness checks for shift operators, null checks when
pointers are assumed by the code to be non-null, and explicit
unreachables.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224255 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/SelectionDAGNodes.h

@@ -768,6 +768,7 @@ protected:
     assert(NumValues == VTs.NumVTs &&
            "NumValues wasn't wide enough for its operands!");
     for (unsigned i = 0; i != Ops.size(); ++i) {
+      assert(OperandList && "no operands available");
       OperandList[i].setUser(this);
       OperandList[i].setInitial(Ops[i]);
     }