PostRASchedulerList.cpp

      if (PendingQueue[i]->getDepth() <= CurCycle) {
        AvailableQueue.push(PendingQueue[i]);
        PendingQueue[i]->isAvailable = true;
        PendingQueue[i] = PendingQueue.back();
        PendingQueue.pop_back();
        --i; --e;
      } else if (PendingQueue[i]->getDepth() < MinDepth)
        MinDepth = PendingQueue[i]->getDepth();
    }

    DEBUG(errs() << "\n*** Examining Available\n";
          LatencyPriorityQueue q = AvailableQueue;
          while (!q.empty()) {
            SUnit *su = q.pop();
            errs() << "Height " << su->getHeight() << ": ";
            su->dump(this);
          });

    SUnit *FoundSUnit = 0;

    bool HasNoopHazards = false;
    while (!AvailableQueue.empty()) {
      SUnit *CurSUnit = AvailableQueue.pop();

      ScheduleHazardRecognizer::HazardType HT =
        HazardRec->getHazardType(CurSUnit);
      if (HT == ScheduleHazardRecognizer::NoHazard) {
        FoundSUnit = CurSUnit;
        break;
      }

      // Remember if this is a noop hazard.
      HasNoopHazards |= HT == ScheduleHazardRecognizer::NoopHazard;

      NotReady.push_back(CurSUnit);
    }

    // Add the nodes that aren't ready back onto the available list.
    if (!NotReady.empty()) {
      AvailableQueue.push_all(NotReady);
      NotReady.clear();
    }

    // If we found a node to schedule, do it now.
    if (FoundSUnit) {
      ScheduleNodeTopDown(FoundSUnit, CurCycle);
      HazardRec->EmitInstruction(FoundSUnit);
      CycleInstCnt++;

      // If we are using the target-specific hazards, then don't
      // advance the cycle time just because we schedule a node. If
      // the target allows it we can schedule multiple nodes in the
      // same cycle.
      if (!EnablePostRAHazardAvoidance) {
        if (FoundSUnit->Latency)  // Don't increment CurCycle for pseudo-ops!
          ++CurCycle;
      }
    } else {
      if (CycleInstCnt > 0) {
        DEBUG(errs() << "*** Finished cycle " << CurCycle << '\n');
        HazardRec->AdvanceCycle();
      } else if (!HasNoopHazards) {
        // Otherwise, we have a pipeline stall, but no other problem,
        // just advance the current cycle and try again.
        DEBUG(errs() << "*** Stall in cycle " << CurCycle << '\n');
        HazardRec->AdvanceCycle();
        ++NumStalls;
      } else {
        // Otherwise, we have no instructions to issue and we have instructions
        // that will fault if we don't do this right.  This is the case for
        // processors without pipeline interlocks and other cases.
        DEBUG(errs() << "*** Emitting noop in cycle " << CurCycle << '\n');
        HazardRec->EmitNoop();
        Sequence.push_back(0);   // NULL here means noop
        ++NumNoops;
      }

      ++CurCycle;
      CycleInstCnt = 0;
    }
  }

#ifndef NDEBUG
  VerifySchedule(/*isBottomUp=*/false);
#endif
}

//===----------------------------------------------------------------------===//
//                         Public Constructor Functions
//===----------------------------------------------------------------------===//

FunctionPass *llvm::createPostRAScheduler() {
  return new PostRAScheduler();
}