ScheduleDAG.cpp revision 66658dd9a1ffe00a5f6e0afca7afb16ec6704ed3 
1//===---- ScheduleDAG.cpp - Implement the ScheduleDAG class ---------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This implements the ScheduleDAG class, which is a base class used by
11// scheduling implementation classes.
12//
13//===----------------------------------------------------------------------===//
14
15#define DEBUG_TYPE "pre-RA-sched"
16#include "llvm/CodeGen/ScheduleDAG.h"
17#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
18#include "llvm/CodeGen/SelectionDAGNodes.h"
19#include "llvm/Support/CommandLine.h"
20#include "llvm/Support/Debug.h"
21#include "llvm/Support/raw_ostream.h"
22#include "llvm/Target/TargetInstrInfo.h"
23#include "llvm/Target/TargetMachine.h"
24#include "llvm/Target/TargetRegisterInfo.h"
25#include <climits>
26using namespace llvm;
27
28#ifndef NDEBUG
29static cl::opt<bool> StressSchedOpt(
30  "stress-sched", cl::Hidden, cl::init(false),
31  cl::desc("Stress test instruction scheduling"));
32#endif
33
34void SchedulingPriorityQueue::anchor() { }
35
36ScheduleDAG::ScheduleDAG(MachineFunction &mf)
37  : TM(mf.getTarget()),
38    TII(TM.getInstrInfo()),
39    TRI(TM.getRegisterInfo()),
40    MF(mf), MRI(mf.getRegInfo()),
41    EntrySU(), ExitSU() {
42#ifndef NDEBUG
43  StressSched = StressSchedOpt;
44#endif
45}
46
47ScheduleDAG::~ScheduleDAG() {}
48
49/// Clear the DAG state (e.g. between scheduling regions).
50void ScheduleDAG::clearDAG() {
51  SUnits.clear();
52  EntrySU = SUnit();
53  ExitSU = SUnit();
54}
55
56/// getInstrDesc helper to handle SDNodes.
57const MCInstrDesc *ScheduleDAG::getNodeDesc(const SDNode *Node) const {
58  if (!Node || !Node->isMachineOpcode()) return NULL;
59  return &TII->get(Node->getMachineOpcode());
60}
61
62/// addPred - This adds the specified edge as a pred of the current node if
63/// not already.  It also adds the current node as a successor of the
64/// specified node.
65bool SUnit::addPred(const SDep &D, bool Required) {
66  // If this node already has this depenence, don't add a redundant one.
67  for (SmallVector<SDep, 4>::iterator I = Preds.begin(), E = Preds.end();
68       I != E; ++I) {
69    // Zero-latency weak edges may be added purely for heuristic ordering. Don't
70    // add them if another kind of edge already exists.
71    if (!Required && I->getSUnit() == D.getSUnit())
72      return false;
73    if (I->overlaps(D)) {
74      // Extend the latency if needed. Equivalent to removePred(I) + addPred(D).
75      if (I->getLatency() < D.getLatency()) {
76        SUnit *PredSU = I->getSUnit();
77        // Find the corresponding successor in N.
78        SDep ForwardD = *I;
79        ForwardD.setSUnit(this);
80        for (SmallVector<SDep, 4>::iterator II = PredSU->Succs.begin(),
81               EE = PredSU->Succs.end(); II != EE; ++II) {
82          if (*II == ForwardD) {
83            II->setLatency(D.getLatency());
84            break;
85          }
86        }
87        I->setLatency(D.getLatency());
88      }
89      return false;
90    }
91  }
92  // Now add a corresponding succ to N.
93  SDep P = D;
94  P.setSUnit(this);
95  SUnit *N = D.getSUnit();
96  // Update the bookkeeping.
97  if (D.getKind() == SDep::Data) {
98    assert(NumPreds < UINT_MAX && "NumPreds will overflow!");
99    assert(N->NumSuccs < UINT_MAX && "NumSuccs will overflow!");
100    ++NumPreds;
101    ++N->NumSuccs;
102  }
103  if (!N->isScheduled) {
104    if (D.isWeak()) {
105      ++WeakPredsLeft;
106    }
107    else {
108      assert(NumPredsLeft < UINT_MAX && "NumPredsLeft will overflow!");
109      ++NumPredsLeft;
110    }
111  }
112  if (!isScheduled) {
113    if (D.isWeak()) {
114      ++N->WeakSuccsLeft;
115    }
116    else {
117      assert(N->NumSuccsLeft < UINT_MAX && "NumSuccsLeft will overflow!");
118      ++N->NumSuccsLeft;
119    }
120  }
121  Preds.push_back(D);
122  N->Succs.push_back(P);
123  if (P.getLatency() != 0) {
124    this->setDepthDirty();
125    N->setHeightDirty();
126  }
127  return true;
128}
129
130/// removePred - This removes the specified edge as a pred of the current
131/// node if it exists.  It also removes the current node as a successor of
132/// the specified node.
133void SUnit::removePred(const SDep &D) {
134  // Find the matching predecessor.
135  for (SmallVector<SDep, 4>::iterator I = Preds.begin(), E = Preds.end();
136       I != E; ++I)
137    if (*I == D) {
138      bool FoundSucc = false;
139      // Find the corresponding successor in N.
140      SDep P = D;
141      P.setSUnit(this);
142      SUnit *N = D.getSUnit();
143      for (SmallVector<SDep, 4>::iterator II = N->Succs.begin(),
144             EE = N->Succs.end(); II != EE; ++II)
145        if (*II == P) {
146          FoundSucc = true;
147          N->Succs.erase(II);
148          break;
149        }
150      assert(FoundSucc && "Mismatching preds / succs lists!");
151      (void)FoundSucc;
152      Preds.erase(I);
153      // Update the bookkeeping.
154      if (P.getKind() == SDep::Data) {
155        assert(NumPreds > 0 && "NumPreds will underflow!");
156        assert(N->NumSuccs > 0 && "NumSuccs will underflow!");
157        --NumPreds;
158        --N->NumSuccs;
159      }
160      if (!N->isScheduled) {
161        if (D.isWeak())
162          --WeakPredsLeft;
163        else {
164          assert(NumPredsLeft > 0 && "NumPredsLeft will underflow!");
165          --NumPredsLeft;
166        }
167      }
168      if (!isScheduled) {
169        if (D.isWeak())
170          --N->WeakSuccsLeft;
171        else {
172          assert(N->NumSuccsLeft > 0 && "NumSuccsLeft will underflow!");
173          --N->NumSuccsLeft;
174        }
175      }
176      if (P.getLatency() != 0) {
177        this->setDepthDirty();
178        N->setHeightDirty();
179      }
180      return;
181    }
182}
183
184void SUnit::setDepthDirty() {
185  if (!isDepthCurrent) return;
186  SmallVector<SUnit*, 8> WorkList;
187  WorkList.push_back(this);
188  do {
189    SUnit *SU = WorkList.pop_back_val();
190    SU->isDepthCurrent = false;
191    for (SUnit::const_succ_iterator I = SU->Succs.begin(),
192         E = SU->Succs.end(); I != E; ++I) {
193      SUnit *SuccSU = I->getSUnit();
194      if (SuccSU->isDepthCurrent)
195        WorkList.push_back(SuccSU);
196    }
197  } while (!WorkList.empty());
198}
199
200void SUnit::setHeightDirty() {
201  if (!isHeightCurrent) return;
202  SmallVector<SUnit*, 8> WorkList;
203  WorkList.push_back(this);
204  do {
205    SUnit *SU = WorkList.pop_back_val();
206    SU->isHeightCurrent = false;
207    for (SUnit::const_pred_iterator I = SU->Preds.begin(),
208         E = SU->Preds.end(); I != E; ++I) {
209      SUnit *PredSU = I->getSUnit();
210      if (PredSU->isHeightCurrent)
211        WorkList.push_back(PredSU);
212    }
213  } while (!WorkList.empty());
214}
215
216/// setDepthToAtLeast - Update this node's successors to reflect the
217/// fact that this node's depth just increased.
218///
219void SUnit::setDepthToAtLeast(unsigned NewDepth) {
220  if (NewDepth <= getDepth())
221    return;
222  setDepthDirty();
223  Depth = NewDepth;
224  isDepthCurrent = true;
225}
226
227/// setHeightToAtLeast - Update this node's predecessors to reflect the
228/// fact that this node's height just increased.
229///
230void SUnit::setHeightToAtLeast(unsigned NewHeight) {
231  if (NewHeight <= getHeight())
232    return;
233  setHeightDirty();
234  Height = NewHeight;
235  isHeightCurrent = true;
236}
237
238/// ComputeDepth - Calculate the maximal path from the node to the exit.
239///
240void SUnit::ComputeDepth() {
241  SmallVector<SUnit*, 8> WorkList;
242  WorkList.push_back(this);
243  do {
244    SUnit *Cur = WorkList.back();
245
246    bool Done = true;
247    unsigned MaxPredDepth = 0;
248    for (SUnit::const_pred_iterator I = Cur->Preds.begin(),
249         E = Cur->Preds.end(); I != E; ++I) {
250      SUnit *PredSU = I->getSUnit();
251      if (PredSU->isDepthCurrent)
252        MaxPredDepth = std::max(MaxPredDepth,
253                                PredSU->Depth + I->getLatency());
254      else {
255        Done = false;
256        WorkList.push_back(PredSU);
257      }
258    }
259
260    if (Done) {
261      WorkList.pop_back();
262      if (MaxPredDepth != Cur->Depth) {
263        Cur->setDepthDirty();
264        Cur->Depth = MaxPredDepth;
265      }
266      Cur->isDepthCurrent = true;
267    }
268  } while (!WorkList.empty());
269}
270
271/// ComputeHeight - Calculate the maximal path from the node to the entry.
272///
273void SUnit::ComputeHeight() {
274  SmallVector<SUnit*, 8> WorkList;
275  WorkList.push_back(this);
276  do {
277    SUnit *Cur = WorkList.back();
278
279    bool Done = true;
280    unsigned MaxSuccHeight = 0;
281    for (SUnit::const_succ_iterator I = Cur->Succs.begin(),
282         E = Cur->Succs.end(); I != E; ++I) {
283      SUnit *SuccSU = I->getSUnit();
284      if (SuccSU->isHeightCurrent)
285        MaxSuccHeight = std::max(MaxSuccHeight,
286                                 SuccSU->Height + I->getLatency());
287      else {
288        Done = false;
289        WorkList.push_back(SuccSU);
290      }
291    }
292
293    if (Done) {
294      WorkList.pop_back();
295      if (MaxSuccHeight != Cur->Height) {
296        Cur->setHeightDirty();
297        Cur->Height = MaxSuccHeight;
298      }
299      Cur->isHeightCurrent = true;
300    }
301  } while (!WorkList.empty());
302}
303
304void SUnit::biasCriticalPath() {
305  if (NumPreds < 2)
306    return;
307
308  SUnit::pred_iterator BestI = Preds.begin();
309  unsigned MaxDepth = BestI->getSUnit()->getDepth();
310  for (SUnit::pred_iterator
311         I = llvm::next(BestI), E = Preds.end(); I != E; ++I) {
312    if (I->getKind() == SDep::Data && I->getSUnit()->getDepth() > MaxDepth)
313      BestI = I;
314  }
315  if (BestI != Preds.begin())
316    std::swap(*Preds.begin(), *BestI);
317}
318
319#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
320/// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or
321/// a group of nodes flagged together.
322void SUnit::dump(const ScheduleDAG *G) const {
323  dbgs() << "SU(" << NodeNum << "): ";
324  G->dumpNode(this);
325}
326
327void SUnit::dumpAll(const ScheduleDAG *G) const {
328  dump(G);
329
330  dbgs() << "  # preds left       : " << NumPredsLeft << "\n";
331  dbgs() << "  # succs left       : " << NumSuccsLeft << "\n";
332  if (WeakPredsLeft)
333    dbgs() << "  # weak preds left  : " << WeakPredsLeft << "\n";
334  if (WeakSuccsLeft)
335    dbgs() << "  # weak succs left  : " << WeakSuccsLeft << "\n";
336  dbgs() << "  # rdefs left       : " << NumRegDefsLeft << "\n";
337  dbgs() << "  Latency            : " << Latency << "\n";
338  dbgs() << "  Depth              : " << Depth << "\n";
339  dbgs() << "  Height             : " << Height << "\n";
340
341  if (Preds.size() != 0) {
342    dbgs() << "  Predecessors:\n";
343    for (SUnit::const_succ_iterator I = Preds.begin(), E = Preds.end();
344         I != E; ++I) {
345      dbgs() << "   ";
346      switch (I->getKind()) {
347      case SDep::Data:        dbgs() << "val "; break;
348      case SDep::Anti:        dbgs() << "anti"; break;
349      case SDep::Output:      dbgs() << "out "; break;
350      case SDep::Order:       dbgs() << "ch  "; break;
351      }
352      dbgs() << "SU(" << I->getSUnit()->NodeNum << ")";
353      if (I->isArtificial())
354        dbgs() << " *";
355      dbgs() << ": Latency=" << I->getLatency();
356      if (I->isAssignedRegDep())
357        dbgs() << " Reg=" << PrintReg(I->getReg(), G->TRI);
358      dbgs() << "\n";
359    }
360  }
361  if (Succs.size() != 0) {
362    dbgs() << "  Successors:\n";
363    for (SUnit::const_succ_iterator I = Succs.begin(), E = Succs.end();
364         I != E; ++I) {
365      dbgs() << "   ";
366      switch (I->getKind()) {
367      case SDep::Data:        dbgs() << "val "; break;
368      case SDep::Anti:        dbgs() << "anti"; break;
369      case SDep::Output:      dbgs() << "out "; break;
370      case SDep::Order:       dbgs() << "ch  "; break;
371      }
372      dbgs() << "SU(" << I->getSUnit()->NodeNum << ")";
373      if (I->isArtificial())
374        dbgs() << " *";
375      dbgs() << ": Latency=" << I->getLatency();
376      dbgs() << "\n";
377    }
378  }
379  dbgs() << "\n";
380}
381#endif
382
383#ifndef NDEBUG
384/// VerifyScheduledDAG - Verify that all SUnits were scheduled and that
385/// their state is consistent. Return the number of scheduled nodes.
386///
387unsigned ScheduleDAG::VerifyScheduledDAG(bool isBottomUp) {
388  bool AnyNotSched = false;
389  unsigned DeadNodes = 0;
390  for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
391    if (!SUnits[i].isScheduled) {
392      if (SUnits[i].NumPreds == 0 && SUnits[i].NumSuccs == 0) {
393        ++DeadNodes;
394        continue;
395      }
396      if (!AnyNotSched)
397        dbgs() << "*** Scheduling failed! ***\n";
398      SUnits[i].dump(this);
399      dbgs() << "has not been scheduled!\n";
400      AnyNotSched = true;
401    }
402    if (SUnits[i].isScheduled &&
403        (isBottomUp ? SUnits[i].getHeight() : SUnits[i].getDepth()) >
404          unsigned(INT_MAX)) {
405      if (!AnyNotSched)
406        dbgs() << "*** Scheduling failed! ***\n";
407      SUnits[i].dump(this);
408      dbgs() << "has an unexpected "
409           << (isBottomUp ? "Height" : "Depth") << " value!\n";
410      AnyNotSched = true;
411    }
412    if (isBottomUp) {
413      if (SUnits[i].NumSuccsLeft != 0) {
414        if (!AnyNotSched)
415          dbgs() << "*** Scheduling failed! ***\n";
416        SUnits[i].dump(this);
417        dbgs() << "has successors left!\n";
418        AnyNotSched = true;
419      }
420    } else {
421      if (SUnits[i].NumPredsLeft != 0) {
422        if (!AnyNotSched)
423          dbgs() << "*** Scheduling failed! ***\n";
424        SUnits[i].dump(this);
425        dbgs() << "has predecessors left!\n";
426        AnyNotSched = true;
427      }
428    }
429  }
430  assert(!AnyNotSched);
431  return SUnits.size() - DeadNodes;
432}
433#endif
434
435/// InitDAGTopologicalSorting - create the initial topological
436/// ordering from the DAG to be scheduled.
437///
438/// The idea of the algorithm is taken from
439/// "Online algorithms for managing the topological order of
440/// a directed acyclic graph" by David J. Pearce and Paul H.J. Kelly
441/// This is the MNR algorithm, which was first introduced by
442/// A. Marchetti-Spaccamela, U. Nanni and H. Rohnert in
443/// "Maintaining a topological order under edge insertions".
444///
445/// Short description of the algorithm:
446///
447/// Topological ordering, ord, of a DAG maps each node to a topological
448/// index so that for all edges X->Y it is the case that ord(X) < ord(Y).
449///
450/// This means that if there is a path from the node X to the node Z,
451/// then ord(X) < ord(Z).
452///
453/// This property can be used to check for reachability of nodes:
454/// if Z is reachable from X, then an insertion of the edge Z->X would
455/// create a cycle.
456///
457/// The algorithm first computes a topological ordering for the DAG by
458/// initializing the Index2Node and Node2Index arrays and then tries to keep
459/// the ordering up-to-date after edge insertions by reordering the DAG.
460///
461/// On insertion of the edge X->Y, the algorithm first marks by calling DFS
462/// the nodes reachable from Y, and then shifts them using Shift to lie
463/// immediately after X in Index2Node.
464void ScheduleDAGTopologicalSort::InitDAGTopologicalSorting() {
465  unsigned DAGSize = SUnits.size();
466  std::vector<SUnit*> WorkList;
467  WorkList.reserve(DAGSize);
468
469  Index2Node.resize(DAGSize);
470  Node2Index.resize(DAGSize);
471
472  // Initialize the data structures.
473  if (ExitSU)
474    WorkList.push_back(ExitSU);
475  for (unsigned i = 0, e = DAGSize; i != e; ++i) {
476    SUnit *SU = &SUnits[i];
477    int NodeNum = SU->NodeNum;
478    unsigned Degree = SU->Succs.size();
479    // Temporarily use the Node2Index array as scratch space for degree counts.
480    Node2Index[NodeNum] = Degree;
481
482    // Is it a node without dependencies?
483    if (Degree == 0) {
484      assert(SU->Succs.empty() && "SUnit should have no successors");
485      // Collect leaf nodes.
486      WorkList.push_back(SU);
487    }
488  }
489
490  int Id = DAGSize;
491  while (!WorkList.empty()) {
492    SUnit *SU = WorkList.back();
493    WorkList.pop_back();
494    if (SU->NodeNum < DAGSize)
495      Allocate(SU->NodeNum, --Id);
496    for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
497         I != E; ++I) {
498      SUnit *SU = I->getSUnit();
499      if (SU->NodeNum < DAGSize && !--Node2Index[SU->NodeNum])
500        // If all dependencies of the node are processed already,
501        // then the node can be computed now.
502        WorkList.push_back(SU);
503    }
504  }
505
506  Visited.resize(DAGSize);
507
508#ifndef NDEBUG
509  // Check correctness of the ordering
510  for (unsigned i = 0, e = DAGSize; i != e; ++i) {
511    SUnit *SU = &SUnits[i];
512    for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
513         I != E; ++I) {
514      assert(Node2Index[SU->NodeNum] > Node2Index[I->getSUnit()->NodeNum] &&
515      "Wrong topological sorting");
516    }
517  }
518#endif
519}
520
521/// AddPred - Updates the topological ordering to accommodate an edge
522/// to be added from SUnit X to SUnit Y.
523void ScheduleDAGTopologicalSort::AddPred(SUnit *Y, SUnit *X) {
524  int UpperBound, LowerBound;
525  LowerBound = Node2Index[Y->NodeNum];
526  UpperBound = Node2Index[X->NodeNum];
527  bool HasLoop = false;
528  // Is Ord(X) < Ord(Y) ?
529  if (LowerBound < UpperBound) {
530    // Update the topological order.
531    Visited.reset();
532    DFS(Y, UpperBound, HasLoop);
533    assert(!HasLoop && "Inserted edge creates a loop!");
534    // Recompute topological indexes.
535    Shift(Visited, LowerBound, UpperBound);
536  }
537}
538
539/// RemovePred - Updates the topological ordering to accommodate an
540/// an edge to be removed from the specified node N from the predecessors
541/// of the current node M.
542void ScheduleDAGTopologicalSort::RemovePred(SUnit *M, SUnit *N) {
543  // InitDAGTopologicalSorting();
544}
545
546/// DFS - Make a DFS traversal to mark all nodes reachable from SU and mark
547/// all nodes affected by the edge insertion. These nodes will later get new
548/// topological indexes by means of the Shift method.
549void ScheduleDAGTopologicalSort::DFS(const SUnit *SU, int UpperBound,
550                                     bool &HasLoop) {
551  std::vector<const SUnit*> WorkList;
552  WorkList.reserve(SUnits.size());
553
554  WorkList.push_back(SU);
555  do {
556    SU = WorkList.back();
557    WorkList.pop_back();
558    Visited.set(SU->NodeNum);
559    for (int I = SU->Succs.size()-1; I >= 0; --I) {
560      unsigned s = SU->Succs[I].getSUnit()->NodeNum;
561      // Edges to non-SUnits are allowed but ignored (e.g. ExitSU).
562      if (s >= Node2Index.size())
563        continue;
564      if (Node2Index[s] == UpperBound) {
565        HasLoop = true;
566        return;
567      }
568      // Visit successors if not already and in affected region.
569      if (!Visited.test(s) && Node2Index[s] < UpperBound) {
570        WorkList.push_back(SU->Succs[I].getSUnit());
571      }
572    }
573  } while (!WorkList.empty());
574}
575
576/// Shift - Renumber the nodes so that the topological ordering is
577/// preserved.
578void ScheduleDAGTopologicalSort::Shift(BitVector& Visited, int LowerBound,
579                                       int UpperBound) {
580  std::vector<int> L;
581  int shift = 0;
582  int i;
583
584  for (i = LowerBound; i <= UpperBound; ++i) {
585    // w is node at topological index i.
586    int w = Index2Node[i];
587    if (Visited.test(w)) {
588      // Unmark.
589      Visited.reset(w);
590      L.push_back(w);
591      shift = shift + 1;
592    } else {
593      Allocate(w, i - shift);
594    }
595  }
596
597  for (unsigned j = 0; j < L.size(); ++j) {
598    Allocate(L[j], i - shift);
599    i = i + 1;
600  }
601}
602
603
604/// WillCreateCycle - Returns true if adding an edge to TargetSU from SU will
605/// create a cycle. If so, it is not safe to call AddPred(TargetSU, SU).
606bool ScheduleDAGTopologicalSort::WillCreateCycle(SUnit *TargetSU, SUnit *SU) {
607  // Is SU reachable from TargetSU via successor edges?
608  if (IsReachable(SU, TargetSU))
609    return true;
610  for (SUnit::pred_iterator
611         I = TargetSU->Preds.begin(), E = TargetSU->Preds.end(); I != E; ++I)
612    if (I->isAssignedRegDep() &&
613        IsReachable(SU, I->getSUnit()))
614      return true;
615  return false;
616}
617
618/// IsReachable - Checks if SU is reachable from TargetSU.
619bool ScheduleDAGTopologicalSort::IsReachable(const SUnit *SU,
620                                             const SUnit *TargetSU) {
621  // If insertion of the edge SU->TargetSU would create a cycle
622  // then there is a path from TargetSU to SU.
623  int UpperBound, LowerBound;
624  LowerBound = Node2Index[TargetSU->NodeNum];
625  UpperBound = Node2Index[SU->NodeNum];
626  bool HasLoop = false;
627  // Is Ord(TargetSU) < Ord(SU) ?
628  if (LowerBound < UpperBound) {
629    Visited.reset();
630    // There may be a path from TargetSU to SU. Check for it.
631    DFS(TargetSU, UpperBound, HasLoop);
632  }
633  return HasLoop;
634}
635
636/// Allocate - assign the topological index to the node n.
637void ScheduleDAGTopologicalSort::Allocate(int n, int index) {
638  Node2Index[n] = index;
639  Index2Node[index] = n;
640}
641
642ScheduleDAGTopologicalSort::
643ScheduleDAGTopologicalSort(std::vector<SUnit> &sunits, SUnit *exitsu)
644  : SUnits(sunits), ExitSU(exitsu) {}
645
646ScheduleHazardRecognizer::~ScheduleHazardRecognizer() {}
647