ScheduleDAG: Cleanup dumping code; NFC

- Instead of having both `SUnit::dump(ScheduleDAG*)` and
  `ScheduleDAG::dumpNode(ScheduleDAG*)`, just keep the latter around.
- Add `ScheduleDAG::dump()` and avoid code duplication in several
  places. Implement it for different ScheduleDAG variants.
- Add `ScheduleDAG::dumpNodeName()` in favor of the `SUnit::print()`
  functions. They were only ever used for debug dumping and putting the
  function into ScheduleDAG is consistent with the `dumpNode()` change.

llvm-svn: 342520
diff --git a/llvm/lib/CodeGen/MachinePipeliner.cpp b/llvm/lib/CodeGen/MachinePipeliner.cpp
index a02669a..988861e 100644
--- a/llvm/lib/CodeGen/MachinePipeliner.cpp
+++ b/llvm/lib/CodeGen/MachinePipeliner.cpp
@@ -886,10 +886,7 @@
   Topo.InitDAGTopologicalSorting();
   postprocessDAG();
   changeDependences();
-  LLVM_DEBUG({
-    for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
-      SUnits[su].dumpAll(this);
-  });
+  LLVM_DEBUG(dump());
 
   NodeSetType NodeSets;
   findCircuits(NodeSets);
@@ -1638,8 +1635,8 @@
     for (ScheduleDAGTopologicalSort::const_iterator I = Topo.begin(),
                                                     E = Topo.end();
          I != E; ++I) {
-      SUnit *SU = &SUnits[*I];
-      SU->dump(this);
+      const SUnit &SU = SUnits[*I];
+      dumpNode(SU);
     }
   });