ScheduleDAG.cpp revision dce4a407a24b04eebc6a376f8e62b41aaa7b071f 
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#include "llvm/CodeGen/ScheduleDAG.h"
16#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
17#include "llvm/CodeGen/SelectionDAGNodes.h"
18#include "llvm/Support/CommandLine.h"
19#include "llvm/Support/Debug.h"
20#include "llvm/Support/raw_ostream.h"
21#include "llvm/Target/TargetInstrInfo.h"
22#include "llvm/Target/TargetMachine.h"
23#include "llvm/Target/TargetRegisterInfo.h"
24#include <climits>
25using namespace llvm;
26
27#define DEBUG_TYPE "pre-RA-sched"
28
29#ifndef NDEBUG
30static cl::opt<bool> StressSchedOpt(
31  "stress-sched", cl::Hidden, cl::init(false),
32  cl::desc("Stress test instruction scheduling"));
33#endif
34
35void SchedulingPriorityQueue::anchor() { }
36
37ScheduleDAG::ScheduleDAG(MachineFunction &mf)
38  : TM(mf.getTarget()),
39    TII(TM.getInstrInfo()),
40    TRI(TM.getRegisterInfo()),
41    MF(mf), MRI(mf.getRegInfo()),
42    EntrySU(), ExitSU() {
43#ifndef NDEBUG
44  StressSched = StressSchedOpt;
45#endif
46}
47
48ScheduleDAG::~ScheduleDAG() {}
49
50/// Clear the DAG state (e.g. between scheduling regions).
51void ScheduleDAG::clearDAG() {
52  SUnits.clear();
53  EntrySU = SUnit();
54  ExitSU = SUnit();
55}
56
57/// getInstrDesc helper to handle SDNodes.
58const MCInstrDesc *ScheduleDAG::getNodeDesc(const SDNode *Node) const {
59  if (!Node || !Node->isMachineOpcode()) return nullptr;
60  return &TII->get(Node->getMachineOpcode());
61}
62
63/// addPred - This adds the specified edge as a pred of the current node if
64/// not already.  It also adds the current node as a successor of the
65/// specified node.
66bool SUnit::addPred(const SDep &D, bool Required) {
67  // If this node already has this dependence, don't add a redundant one.
68  for (SmallVectorImpl<SDep>::iterator I = Preds.begin(), E = Preds.end();
69         I != E; ++I) {
70    // Zero-latency weak edges may be added purely for heuristic ordering. Don't
71    // add them if another kind of edge already exists.
72    if (!Required && I->getSUnit() == D.getSUnit())
73      return false;
74    if (I->overlaps(D)) {
75      // Extend the latency if needed. Equivalent to removePred(I) + addPred(D).
76      if (I->getLatency() < D.getLatency()) {
77        SUnit *PredSU = I->getSUnit();
78        // Find the corresponding successor in N.
79        SDep ForwardD = *I;
80        ForwardD.setSUnit(this);
81        for (SmallVectorImpl<SDep>::iterator II = PredSU->Succs.begin(),
82               EE = PredSU->Succs.end(); II != EE; ++II) {
83          if (*II == ForwardD) {
84            II->setLatency(D.getLatency());
85            break;
86          }
87        }
88        I->setLatency(D.getLatency());
89      }
90      return false;
91    }
92  }
93  // Now add a corresponding succ to N.
94  SDep P = D;
95  P.setSUnit(this);
96  SUnit *N = D.getSUnit();
97  // Update the bookkeeping.
98  if (D.getKind() == SDep::Data) {
99    assert(NumPreds < UINT_MAX && "NumPreds will overflow!");
100    assert(N->NumSuccs < UINT_MAX && "NumSuccs will overflow!");
101    ++NumPreds;
102    ++N->NumSuccs;
103  }
104  if (!N->isScheduled) {
105    if (D.isWeak()) {
106      ++WeakPredsLeft;
107    }
108    else {
109      assert(NumPredsLeft < UINT_MAX && "NumPredsLeft will overflow!");
110      ++NumPredsLeft;
111    }
112  }
113  if (!isScheduled) {
114    if (D.isWeak()) {
115      ++N->WeakSuccsLeft;
116    }
117    else {
118      assert(N->NumSuccsLeft < UINT_MAX && "NumSuccsLeft will overflow!");
119      ++N->NumSuccsLeft;
120    }
121  }
122  Preds.push_back(D);
123  N->Succs.push_back(P);
124  if (P.getLatency() != 0) {
125    this->setDepthDirty();
126    N->setHeightDirty();
127  }
128  return true;
129}
130
131/// removePred - This removes the specified edge as a pred of the current
132/// node if it exists.  It also removes the current node as a successor of
133/// the specified node.
134void SUnit::removePred(const SDep &D) {
135  // Find the matching predecessor.
136  for (SmallVectorImpl<SDep>::iterator I = Preds.begin(), E = Preds.end();
137         I != E; ++I)
138    if (*I == D) {
139      // Find the corresponding successor in N.
140      SDep P = D;
141      P.setSUnit(this);
142      SUnit *N = D.getSUnit();
143      SmallVectorImpl<SDep>::iterator Succ = std::find(N->Succs.begin(),
144                                                       N->Succs.end(), P);
145      assert(Succ != N->Succs.end() && "Mismatching preds / succs lists!");
146      N->Succs.erase(Succ);
147      Preds.erase(I);
148      // Update the bookkeeping.
149      if (P.getKind() == SDep::Data) {
150        assert(NumPreds > 0 && "NumPreds will underflow!");
151        assert(N->NumSuccs > 0 && "NumSuccs will underflow!");
152        --NumPreds;
153        --N->NumSuccs;
154      }
155      if (!N->isScheduled) {
156        if (D.isWeak())
157          --WeakPredsLeft;
158        else {
159          assert(NumPredsLeft > 0 && "NumPredsLeft will underflow!");
160          --NumPredsLeft;
161        }
162      }
163      if (!isScheduled) {
164        if (D.isWeak())
165          --N->WeakSuccsLeft;
166        else {
167          assert(N->NumSuccsLeft > 0 && "NumSuccsLeft will underflow!");
168          --N->NumSuccsLeft;
169        }
170      }
171      if (P.getLatency() != 0) {
172        this->setDepthDirty();
173        N->setHeightDirty();
174      }
175      return;
176    }
177}
178
179void SUnit::setDepthDirty() {
180  if (!isDepthCurrent) return;
181  SmallVector<SUnit*, 8> WorkList;
182  WorkList.push_back(this);
183  do {
184    SUnit *SU = WorkList.pop_back_val();
185    SU->isDepthCurrent = false;
186    for (SUnit::const_succ_iterator I = SU->Succs.begin(),
187         E = SU->Succs.end(); I != E; ++I) {
188      SUnit *SuccSU = I->getSUnit();
189      if (SuccSU->isDepthCurrent)
190        WorkList.push_back(SuccSU);
191    }
192  } while (!WorkList.empty());
193}
194
195void SUnit::setHeightDirty() {
196  if (!isHeightCurrent) return;
197  SmallVector<SUnit*, 8> WorkList;
198  WorkList.push_back(this);
199  do {
200    SUnit *SU = WorkList.pop_back_val();
201    SU->isHeightCurrent = false;
202    for (SUnit::const_pred_iterator I = SU->Preds.begin(),
203         E = SU->Preds.end(); I != E; ++I) {
204      SUnit *PredSU = I->getSUnit();
205      if (PredSU->isHeightCurrent)
206        WorkList.push_back(PredSU);
207    }
208  } while (!WorkList.empty());
209}
210
211/// setDepthToAtLeast - Update this node's successors to reflect the
212/// fact that this node's depth just increased.
213///
214void SUnit::setDepthToAtLeast(unsigned NewDepth) {
215  if (NewDepth <= getDepth())
216    return;
217  setDepthDirty();
218  Depth = NewDepth;
219  isDepthCurrent = true;
220}
221
222/// setHeightToAtLeast - Update this node's predecessors to reflect the
223/// fact that this node's height just increased.
224///
225void SUnit::setHeightToAtLeast(unsigned NewHeight) {
226  if (NewHeight <= getHeight())
227    return;
228  setHeightDirty();
229  Height = NewHeight;
230  isHeightCurrent = true;
231}
232
233/// ComputeDepth - Calculate the maximal path from the node to the exit.
234///
235void SUnit::ComputeDepth() {
236  SmallVector<SUnit*, 8> WorkList;
237  WorkList.push_back(this);
238  do {
239    SUnit *Cur = WorkList.back();
240
241    bool Done = true;
242    unsigned MaxPredDepth = 0;
243    for (SUnit::const_pred_iterator I = Cur->Preds.begin(),
244         E = Cur->Preds.end(); I != E; ++I) {
245      SUnit *PredSU = I->getSUnit();
246      if (PredSU->isDepthCurrent)
247        MaxPredDepth = std::max(MaxPredDepth,
248                                PredSU->Depth + I->getLatency());
249      else {
250        Done = false;
251        WorkList.push_back(PredSU);
252      }
253    }
254
255    if (Done) {
256      WorkList.pop_back();
257      if (MaxPredDepth != Cur->Depth) {
258        Cur->setDepthDirty();
259        Cur->Depth = MaxPredDepth;
260      }
261      Cur->isDepthCurrent = true;
262    }
263  } while (!WorkList.empty());
264}
265
266/// ComputeHeight - Calculate the maximal path from the node to the entry.
267///
268void SUnit::ComputeHeight() {
269  SmallVector<SUnit*, 8> WorkList;
270  WorkList.push_back(this);
271  do {
272    SUnit *Cur = WorkList.back();
273
274    bool Done = true;
275    unsigned MaxSuccHeight = 0;
276    for (SUnit::const_succ_iterator I = Cur->Succs.begin(),
277         E = Cur->Succs.end(); I != E; ++I) {
278      SUnit *SuccSU = I->getSUnit();
279      if (SuccSU->isHeightCurrent)
280        MaxSuccHeight = std::max(MaxSuccHeight,
281                                 SuccSU->Height + I->getLatency());
282      else {
283        Done = false;
284        WorkList.push_back(SuccSU);
285      }
286    }
287
288    if (Done) {
289      WorkList.pop_back();
290      if (MaxSuccHeight != Cur->Height) {
291        Cur->setHeightDirty();
292        Cur->Height = MaxSuccHeight;
293      }
294      Cur->isHeightCurrent = true;
295    }
296  } while (!WorkList.empty());
297}
298
299void SUnit::biasCriticalPath() {
300  if (NumPreds < 2)
301    return;
302
303  SUnit::pred_iterator BestI = Preds.begin();
304  unsigned MaxDepth = BestI->getSUnit()->getDepth();
305  for (SUnit::pred_iterator I = std::next(BestI), E = Preds.end(); I != E;
306       ++I) {
307    if (I->getKind() == SDep::Data && I->getSUnit()->getDepth() > MaxDepth)
308      BestI = I;
309  }
310  if (BestI != Preds.begin())
311    std::swap(*Preds.begin(), *BestI);
312}
313
314#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
315/// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or
316/// a group of nodes flagged together.
317void SUnit::dump(const ScheduleDAG *G) const {
318  dbgs() << "SU(" << NodeNum << "): ";
319  G->dumpNode(this);
320}
321
322void SUnit::dumpAll(const ScheduleDAG *G) const {
323  dump(G);
324
325  dbgs() << "  # preds left       : " << NumPredsLeft << "\n";
326  dbgs() << "  # succs left       : " << NumSuccsLeft << "\n";
327  if (WeakPredsLeft)
328    dbgs() << "  # weak preds left  : " << WeakPredsLeft << "\n";
329  if (WeakSuccsLeft)
330    dbgs() << "  # weak succs left  : " << WeakSuccsLeft << "\n";
331  dbgs() << "  # rdefs left       : " << NumRegDefsLeft << "\n";
332  dbgs() << "  Latency            : " << Latency << "\n";
333  dbgs() << "  Depth              : " << getDepth() << "\n";
334  dbgs() << "  Height             : " << getHeight() << "\n";
335
336  if (Preds.size() != 0) {
337    dbgs() << "  Predecessors:\n";
338    for (SUnit::const_succ_iterator I = Preds.begin(), E = Preds.end();
339         I != E; ++I) {
340      dbgs() << "   ";
341      switch (I->getKind()) {
342      case SDep::Data:        dbgs() << "val "; break;
343      case SDep::Anti:        dbgs() << "anti"; break;
344      case SDep::Output:      dbgs() << "out "; break;
345      case SDep::Order:       dbgs() << "ch  "; break;
346      }
347      dbgs() << "SU(" << I->getSUnit()->NodeNum << ")";
348      if (I->isArtificial())
349        dbgs() << " *";
350      dbgs() << ": Latency=" << I->getLatency();
351      if (I->isAssignedRegDep())
352        dbgs() << " Reg=" << PrintReg(I->getReg(), G->TRI);
353      dbgs() << "\n";
354    }
355  }
356  if (Succs.size() != 0) {
357    dbgs() << "  Successors:\n";
358    for (SUnit::const_succ_iterator I = Succs.begin(), E = Succs.end();
359         I != E; ++I) {
360      dbgs() << "   ";
361      switch (I->getKind()) {
362      case SDep::Data:        dbgs() << "val "; break;
363      case SDep::Anti:        dbgs() << "anti"; break;
364      case SDep::Output:      dbgs() << "out "; break;
365      case SDep::Order:       dbgs() << "ch  "; break;
366      }
367      dbgs() << "SU(" << I->getSUnit()->NodeNum << ")";
368      if (I->isArtificial())
369        dbgs() << " *";
370      dbgs() << ": Latency=" << I->getLatency();
371      if (I->isAssignedRegDep())
372        dbgs() << " Reg=" << PrintReg(I->getReg(), G->TRI);
373      dbgs() << "\n";
374    }
375  }
376  dbgs() << "\n";
377}
378#endif
379
380#ifndef NDEBUG
381/// VerifyScheduledDAG - Verify that all SUnits were scheduled and that
382/// their state is consistent. Return the number of scheduled nodes.
383///
384unsigned ScheduleDAG::VerifyScheduledDAG(bool isBottomUp) {
385  bool AnyNotSched = false;
386  unsigned DeadNodes = 0;
387  for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
388    if (!SUnits[i].isScheduled) {
389      if (SUnits[i].NumPreds == 0 && SUnits[i].NumSuccs == 0) {
390        ++DeadNodes;
391        continue;
392      }
393      if (!AnyNotSched)
394        dbgs() << "*** Scheduling failed! ***\n";
395      SUnits[i].dump(this);
396      dbgs() << "has not been scheduled!\n";
397      AnyNotSched = true;
398    }
399    if (SUnits[i].isScheduled &&
400        (isBottomUp ? SUnits[i].getHeight() : SUnits[i].getDepth()) >
401          unsigned(INT_MAX)) {
402      if (!AnyNotSched)
403        dbgs() << "*** Scheduling failed! ***\n";
404      SUnits[i].dump(this);
405      dbgs() << "has an unexpected "
406           << (isBottomUp ? "Height" : "Depth") << " value!\n";
407      AnyNotSched = true;
408    }
409    if (isBottomUp) {
410      if (SUnits[i].NumSuccsLeft != 0) {
411        if (!AnyNotSched)
412          dbgs() << "*** Scheduling failed! ***\n";
413        SUnits[i].dump(this);
414        dbgs() << "has successors left!\n";
415        AnyNotSched = true;
416      }
417    } else {
418      if (SUnits[i].NumPredsLeft != 0) {
419        if (!AnyNotSched)
420          dbgs() << "*** Scheduling failed! ***\n";
421        SUnits[i].dump(this);
422        dbgs() << "has predecessors left!\n";
423        AnyNotSched = true;
424      }
425    }
426  }
427  assert(!AnyNotSched);
428  return SUnits.size() - DeadNodes;
429}
430#endif
431
432/// InitDAGTopologicalSorting - create the initial topological
433/// ordering from the DAG to be scheduled.
434///
435/// The idea of the algorithm is taken from
436/// "Online algorithms for managing the topological order of
437/// a directed acyclic graph" by David J. Pearce and Paul H.J. Kelly
438/// This is the MNR algorithm, which was first introduced by
439/// A. Marchetti-Spaccamela, U. Nanni and H. Rohnert in
440/// "Maintaining a topological order under edge insertions".
441///
442/// Short description of the algorithm:
443///
444/// Topological ordering, ord, of a DAG maps each node to a topological
445/// index so that for all edges X->Y it is the case that ord(X) < ord(Y).
446///
447/// This means that if there is a path from the node X to the node Z,
448/// then ord(X) < ord(Z).
449///
450/// This property can be used to check for reachability of nodes:
451/// if Z is reachable from X, then an insertion of the edge Z->X would
452/// create a cycle.
453///
454/// The algorithm first computes a topological ordering for the DAG by
455/// initializing the Index2Node and Node2Index arrays and then tries to keep
456/// the ordering up-to-date after edge insertions by reordering the DAG.
457///
458/// On insertion of the edge X->Y, the algorithm first marks by calling DFS
459/// the nodes reachable from Y, and then shifts them using Shift to lie
460/// immediately after X in Index2Node.
461void ScheduleDAGTopologicalSort::InitDAGTopologicalSorting() {
462  unsigned DAGSize = SUnits.size();
463  std::vector<SUnit*> WorkList;
464  WorkList.reserve(DAGSize);
465
466  Index2Node.resize(DAGSize);
467  Node2Index.resize(DAGSize);
468
469  // Initialize the data structures.
470  if (ExitSU)
471    WorkList.push_back(ExitSU);
472  for (unsigned i = 0, e = DAGSize; i != e; ++i) {
473    SUnit *SU = &SUnits[i];
474    int NodeNum = SU->NodeNum;
475    unsigned Degree = SU->Succs.size();
476    // Temporarily use the Node2Index array as scratch space for degree counts.
477    Node2Index[NodeNum] = Degree;
478
479    // Is it a node without dependencies?
480    if (Degree == 0) {
481      assert(SU->Succs.empty() && "SUnit should have no successors");
482      // Collect leaf nodes.
483      WorkList.push_back(SU);
484    }
485  }
486
487  int Id = DAGSize;
488  while (!WorkList.empty()) {
489    SUnit *SU = WorkList.back();
490    WorkList.pop_back();
491    if (SU->NodeNum < DAGSize)
492      Allocate(SU->NodeNum, --Id);
493    for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
494         I != E; ++I) {
495      SUnit *SU = I->getSUnit();
496      if (SU->NodeNum < DAGSize && !--Node2Index[SU->NodeNum])
497        // If all dependencies of the node are processed already,
498        // then the node can be computed now.
499        WorkList.push_back(SU);
500    }
501  }
502
503  Visited.resize(DAGSize);
504
505#ifndef NDEBUG
506  // Check correctness of the ordering
507  for (unsigned i = 0, e = DAGSize; i != e; ++i) {
508    SUnit *SU = &SUnits[i];
509    for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
510         I != E; ++I) {
511      assert(Node2Index[SU->NodeNum] > Node2Index[I->getSUnit()->NodeNum] &&
512      "Wrong topological sorting");
513    }
514  }
515#endif
516}
517
518/// AddPred - Updates the topological ordering to accommodate an edge
519/// to be added from SUnit X to SUnit Y.
520void ScheduleDAGTopologicalSort::AddPred(SUnit *Y, SUnit *X) {
521  int UpperBound, LowerBound;
522  LowerBound = Node2Index[Y->NodeNum];
523  UpperBound = Node2Index[X->NodeNum];
524  bool HasLoop = false;
525  // Is Ord(X) < Ord(Y) ?
526  if (LowerBound < UpperBound) {
527    // Update the topological order.
528    Visited.reset();
529    DFS(Y, UpperBound, HasLoop);
530    assert(!HasLoop && "Inserted edge creates a loop!");
531    // Recompute topological indexes.
532    Shift(Visited, LowerBound, UpperBound);
533  }
534}
535
536/// RemovePred - Updates the topological ordering to accommodate an
537/// an edge to be removed from the specified node N from the predecessors
538/// of the current node M.
539void ScheduleDAGTopologicalSort::RemovePred(SUnit *M, SUnit *N) {
540  // InitDAGTopologicalSorting();
541}
542
543/// DFS - Make a DFS traversal to mark all nodes reachable from SU and mark
544/// all nodes affected by the edge insertion. These nodes will later get new
545/// topological indexes by means of the Shift method.
546void ScheduleDAGTopologicalSort::DFS(const SUnit *SU, int UpperBound,
547                                     bool &HasLoop) {
548  std::vector<const SUnit*> WorkList;
549  WorkList.reserve(SUnits.size());
550
551  WorkList.push_back(SU);
552  do {
553    SU = WorkList.back();
554    WorkList.pop_back();
555    Visited.set(SU->NodeNum);
556    for (int I = SU->Succs.size()-1; I >= 0; --I) {
557      unsigned s = SU->Succs[I].getSUnit()->NodeNum;
558      // Edges to non-SUnits are allowed but ignored (e.g. ExitSU).
559      if (s >= Node2Index.size())
560        continue;
561      if (Node2Index[s] == UpperBound) {
562        HasLoop = true;
563        return;
564      }
565      // Visit successors if not already and in affected region.
566      if (!Visited.test(s) && Node2Index[s] < UpperBound) {
567        WorkList.push_back(SU->Succs[I].getSUnit());
568      }
569    }
570  } while (!WorkList.empty());
571}
572
573/// Shift - Renumber the nodes so that the topological ordering is
574/// preserved.
575void ScheduleDAGTopologicalSort::Shift(BitVector& Visited, int LowerBound,
576                                       int UpperBound) {
577  std::vector<int> L;
578  int shift = 0;
579  int i;
580
581  for (i = LowerBound; i <= UpperBound; ++i) {
582    // w is node at topological index i.
583    int w = Index2Node[i];
584    if (Visited.test(w)) {
585      // Unmark.
586      Visited.reset(w);
587      L.push_back(w);
588      shift = shift + 1;
589    } else {
590      Allocate(w, i - shift);
591    }
592  }
593
594  for (unsigned j = 0; j < L.size(); ++j) {
595    Allocate(L[j], i - shift);
596    i = i + 1;
597  }
598}
599
600
601/// WillCreateCycle - Returns true if adding an edge to TargetSU from SU will
602/// create a cycle. If so, it is not safe to call AddPred(TargetSU, SU).
603bool ScheduleDAGTopologicalSort::WillCreateCycle(SUnit *TargetSU, SUnit *SU) {
604  // Is SU reachable from TargetSU via successor edges?
605  if (IsReachable(SU, TargetSU))
606    return true;
607  for (SUnit::pred_iterator
608         I = TargetSU->Preds.begin(), E = TargetSU->Preds.end(); I != E; ++I)
609    if (I->isAssignedRegDep() &&
610        IsReachable(SU, I->getSUnit()))
611      return true;
612  return false;
613}
614
615/// IsReachable - Checks if SU is reachable from TargetSU.
616bool ScheduleDAGTopologicalSort::IsReachable(const SUnit *SU,
617                                             const SUnit *TargetSU) {
618  // If insertion of the edge SU->TargetSU would create a cycle
619  // then there is a path from TargetSU to SU.
620  int UpperBound, LowerBound;
621  LowerBound = Node2Index[TargetSU->NodeNum];
622  UpperBound = Node2Index[SU->NodeNum];
623  bool HasLoop = false;
624  // Is Ord(TargetSU) < Ord(SU) ?
625  if (LowerBound < UpperBound) {
626    Visited.reset();
627    // There may be a path from TargetSU to SU. Check for it.
628    DFS(TargetSU, UpperBound, HasLoop);
629  }
630  return HasLoop;
631}
632
633/// Allocate - assign the topological index to the node n.
634void ScheduleDAGTopologicalSort::Allocate(int n, int index) {
635  Node2Index[n] = index;
636  Index2Node[index] = n;
637}
638
639ScheduleDAGTopologicalSort::
640ScheduleDAGTopologicalSort(std::vector<SUnit> &sunits, SUnit *exitsu)
641  : SUnits(sunits), ExitSU(exitsu) {}
642
643ScheduleHazardRecognizer::~ScheduleHazardRecognizer() {}
644