[Pipeliner] Fix the Schedule DAG topoligical order.

This patch updates the DAG change to reflect in the topological ordering
of the nodes.

Differential Revision: https://reviews.llvm.org/D53105

llvm-svn: 344282

llvm/lib/CodeGen/MachinePipeliner.cpp

@@ -1295,6 +1295,7 @@ void SwingSchedulerDAG::changeDependences() {
     // Add a dependence between the new instruction and the instruction
     // that defines the new base.
     SDep Dep(&I, SDep::Anti, NewBase);
+    Topo.AddPred(LastSU, &I);
     LastSU->addPred(Dep);
 
     // Remember the base and offset information so that we can update the