1 files changed, 23 insertions, 12 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp
index e43b992407b..1cd893e587d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp
@@ -90,6 +90,7 @@ public:
 
 private:
   void ReleasePred(SUnit *SU, SDep *PredEdge);
+  void ReleasePredecessors(SUnit *SU, unsigned CurCycle);
   void ScheduleNodeBottomUp(SUnit*, unsigned);
   SUnit *CopyAndMoveSuccessors(SUnit*);
   void InsertCopiesAndMoveSuccs(SUnit*, unsigned,
@@ -142,23 +143,15 @@ void ScheduleDAGFast::ReleasePred(SUnit *SU, SDep *PredEdge) {
   }
 #endif
   
-  if (PredSU->NumSuccsLeft == 0) {
+  // If all the node's successors are scheduled, this node is ready
+  // to be scheduled. Ignore the special EntrySU node.
+  if (PredSU->NumSuccsLeft == 0 && PredSU != &EntrySU) {
     PredSU->isAvailable = true;
     AvailableQueue.push(PredSU);
   }
 }
 
-/// ScheduleNodeBottomUp - Add the node to the schedule. Decrement the pending
-/// count of its predecessors. If a predecessor pending count is zero, add it to
-/// the Available queue.
-void ScheduleDAGFast::ScheduleNodeBottomUp(SUnit *SU, unsigned CurCycle) {
-  DOUT << "*** Scheduling [" << CurCycle << "]: ";
-  DEBUG(SU->dump(this));
-
-  assert(CurCycle >= SU->getHeight() && "Node scheduled below its height!");
-  SU->setHeightToAtLeast(CurCycle);
-  Sequence.push_back(SU);
-
+void ScheduleDAGFast::ReleasePredecessors(SUnit *SU, unsigned CurCycle) {
   // Bottom up: release predecessors
   for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
        I != E; ++I) {
@@ -175,6 +168,20 @@ void ScheduleDAGFast::ScheduleNodeBottomUp(SUnit *SU, unsigned CurCycle) {
       }
     }
   }
+}
+
+/// ScheduleNodeBottomUp - Add the node to the schedule. Decrement the pending
+/// count of its predecessors. If a predecessor pending count is zero, add it to
+/// the Available queue.
+void ScheduleDAGFast::ScheduleNodeBottomUp(SUnit *SU, unsigned CurCycle) {
+  DOUT << "*** Scheduling [" << CurCycle << "]: ";
+  DEBUG(SU->dump(this));
+
+  assert(CurCycle >= SU->getHeight() && "Node scheduled below its height!");
+  SU->setHeightToAtLeast(CurCycle);
+  Sequence.push_back(SU);
+
+  ReleasePredecessors(SU, CurCycle);
 
   // Release all the implicit physical register defs that are live.
   for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
@@ -480,6 +487,10 @@ bool ScheduleDAGFast::DelayForLiveRegsBottomUp(SUnit *SU,
 /// schedulers.
 void ScheduleDAGFast::ListScheduleBottomUp() {
   unsigned CurCycle = 0;
+
+  // Release any predecessors of the special Exit node.
+  ReleasePredecessors(&ExitSU, CurCycle);
+
   // Add root to Available queue.
   if (!SUnits.empty()) {
     SUnit *RootSU = &SUnits[DAG->getRoot().getNode()->getNodeId()];