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