Index: lib/Target/AMDGPU/SIMachineScheduler.cpp
===================================================================
--- lib/Target/AMDGPU/SIMachineScheduler.cpp
+++ lib/Target/AMDGPU/SIMachineScheduler.cpp
@@ -1842,11 +1842,11 @@
 
     for (SDep& PredDep : SU->Preds) {
       SUnit *Pred = PredDep.getSUnit();
+      if (Pred->NodeNum >= DAGSize)
+        continue;
       if (SITII->isLowLatencyInstruction(*Pred->getInstr())) {
         IsLowLatencyUser = true;
       }
-      if (Pred->NodeNum >= DAGSize)
-        continue;
       unsigned PredPos = ScheduledSUnitsInv[Pred->NodeNum];
       if (PredPos >= MinPos)
         MinPos = PredPos + 1;
@@ -1877,7 +1877,8 @@
       bool CopyForLowLat = false;
       for (SDep& SuccDep : SU->Succs) {
         SUnit *Succ = SuccDep.getSUnit();
-        if (SITII->isLowLatencyInstruction(*Succ->getInstr())) {
+        if (Succ->NodeNum < DAGSize &&
+            SITII->isLowLatencyInstruction(*Succ->getInstr())) {
           CopyForLowLat = true;
         }
       }