[MachineScheduler] Dump SUnits before calling SchedImpl->initialize()

[jonpa]

Summary

This is a NFC simple patch that changes the DEBUG dumping in the MachineScheduler so that the dumping of the built SUnits is done before the SchedImpl->initialize() is called.

This is better on SystemZ, since it has a strategy that does some dumping at the start of the region, and it is not possible to easily read it if it is output above a long list of SU.

Is this OK for everyone?

[javed.absar]

I assume no tests are impacted by this. Otherwise, looks LGTM

[jonpa]

In D44089#1027091, @javed.absar wrote:

I assume no tests are impacted by this. Otherwise, looks LGTM

Yes, all tests pass unmodified.

[jonpa]

Thanks. r326716

lib/CodeGen/MachineScheduler.cpp

void ScheduleDAGMI::schedule() {
 
   Topo.InitDAGTopologicalSorting();
 
   postprocessDAG();
 
   SmallVector<SUnit*, 8> TopRoots, BotRoots;
   findRootsAndBiasEdges(TopRoots, BotRoots);
 
-  // Initialize the strategy before modifying the DAG.
-  // This may initialize a DFSResult to be used for queue priority.
-  SchedImpl->initialize(this);
-
   DEBUG(
     if (EntrySU.getInstr() != nullptr)
       EntrySU.dumpAll(this);
     for (const SUnit &SU : SUnits)
       SU.dumpAll(this);
     if (ExitSU.getInstr() != nullptr)
       ExitSU.dumpAll(this);
   );
   if (ViewMISchedDAGs) viewGraph();
 
+  // Initialize the strategy before modifying the DAG.
+  // This may initialize a DFSResult to be used for queue priority.
+  SchedImpl->initialize(this);
+
   // Initialize ready queues now that the DAG and priority data are finalized.
   initQueues(TopRoots, BotRoots);
 
   bool IsTopNode = false;
   while (true) {
     DEBUG(dbgs() << "** ScheduleDAGMI::schedule picking next node\n");
     SUnit *SU = SchedImpl->pickNode(IsTopNode);
     if (!SU) break;