1 //===------- llvm/CodeGen/ScheduleDAG.h - Common Base Class------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the ScheduleDAG class, which is used as the common
11 // base class for instruction schedulers. This encapsulates the scheduling DAG,
12 // which is shared between SelectionDAG and MachineInstr scheduling.
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_CODEGEN_SCHEDULEDAG_H
17 #define LLVM_CODEGEN_SCHEDULEDAG_H
19 #include "llvm/CodeGen/MachineBasicBlock.h"
20 #include "llvm/Target/TargetLowering.h"
21 #include "llvm/ADT/DenseMap.h"
22 #include "llvm/ADT/BitVector.h"
23 #include "llvm/ADT/GraphTraits.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/ADT/PointerIntPair.h"
30 class MachineConstantPool;
31 class MachineFunction;
32 class MachineRegisterInfo;
34 class TargetRegisterInfo;
37 class TargetInstrInfo;
40 class TargetRegisterClass;
41 template<class Graph> class GraphWriter;
43 /// SDep - Scheduling dependency. This represents one direction of an
44 /// edge in the scheduling DAG.
47 /// Kind - These are the different kinds of scheduling dependencies.
49 Data, ///< Regular data dependence (aka true-dependence).
50 Anti, ///< A register anti-dependedence (aka WAR).
51 Output, ///< A register output-dependence (aka WAW).
52 Order ///< Any other ordering dependency.
56 Barrier, ///< An unknown scheduling barrier.
57 MayAliasMem, ///< Nonvolatile load/Store instructions that may alias.
58 MustAliasMem, ///< Nonvolatile load/Store instructions that must alias.
59 Artificial ///< Arbitrary weak DAG edge (no actual dependence).
63 /// Dep - A pointer to the depending/depended-on SUnit, and an enum
64 /// indicating the kind of the dependency.
65 PointerIntPair<SUnit *, 2, Kind> Dep;
67 /// Contents - A union discriminated by the dependence kind.
69 /// Reg - For Data, Anti, and Output dependencies, the associated
70 /// register. For Data dependencies that don't currently have a register
71 /// assigned, this is set to zero.
74 /// Order - Additional information about Order dependencies.
75 unsigned OrdKind; // enum OrderKind
78 /// Latency - The time associated with this edge. Often this is just
79 /// the value of the Latency field of the predecessor, however advanced
80 /// models may provide additional information about specific edges.
82 /// Record MinLatency seperately from "expected" Latency.
84 /// FIXME: this field is not packed on LP64. Convert to 16-bit DAG edge
85 /// latency after introducing saturating truncation.
89 /// SDep - Construct a null SDep. This is only for use by container
90 /// classes which require default constructors. SUnits may not
91 /// have null SDep edges.
92 SDep() : Dep(0, Data) {}
94 /// SDep - Construct an SDep with the specified values.
95 SDep(SUnit *S, Kind kind, unsigned Reg)
96 : Dep(S, kind), Contents() {
99 llvm_unreachable("Reg given for non-register dependence!");
103 "SDep::Anti and SDep::Output must use a non-zero Reg!");
112 MinLatency = Latency;
114 SDep(SUnit *S, OrderKind kind)
115 : Dep(S, Order), Contents(), Latency(0), MinLatency(0) {
116 Contents.OrdKind = kind;
119 /// Return true if the specified SDep is equivalent except for latency.
120 bool overlaps(const SDep &Other) const {
121 if (Dep != Other.Dep) return false;
122 switch (Dep.getInt()) {
126 return Contents.Reg == Other.Contents.Reg;
128 return Contents.OrdKind == Other.Contents.OrdKind;
130 llvm_unreachable("Invalid dependency kind!");
133 bool operator==(const SDep &Other) const {
134 return overlaps(Other)
135 && Latency == Other.Latency && MinLatency == Other.MinLatency;
138 bool operator!=(const SDep &Other) const {
139 return !operator==(Other);
142 /// getLatency - Return the latency value for this edge, which roughly
143 /// means the minimum number of cycles that must elapse between the
144 /// predecessor and the successor, given that they have this edge
146 unsigned getLatency() const {
150 /// setLatency - Set the latency for this edge.
151 void setLatency(unsigned Lat) {
155 /// getMinLatency - Return the minimum latency for this edge. Minimum
156 /// latency is used for scheduling groups, while normal (expected) latency
157 /// is for instruction cost and critical path.
158 unsigned getMinLatency() const {
162 /// setMinLatency - Set the minimum latency for this edge.
163 void setMinLatency(unsigned Lat) {
167 //// getSUnit - Return the SUnit to which this edge points.
168 SUnit *getSUnit() const {
169 return Dep.getPointer();
172 //// setSUnit - Assign the SUnit to which this edge points.
173 void setSUnit(SUnit *SU) {
177 /// getKind - Return an enum value representing the kind of the dependence.
178 Kind getKind() const {
182 /// isCtrl - Shorthand for getKind() != SDep::Data.
183 bool isCtrl() const {
184 return getKind() != Data;
187 /// isNormalMemory - Test if this is an Order dependence between two
188 /// memory accesses where both sides of the dependence access memory
189 /// in non-volatile and fully modeled ways.
190 bool isNormalMemory() const {
191 return getKind() == Order && (Contents.OrdKind == MayAliasMem
192 || Contents.OrdKind == MustAliasMem);
195 /// isMustAlias - Test if this is an Order dependence that is marked
196 /// as "must alias", meaning that the SUnits at either end of the edge
197 /// have a memory dependence on a known memory location.
198 bool isMustAlias() const {
199 return getKind() == Order && Contents.OrdKind == MustAliasMem;
202 /// isArtificial - Test if this is an Order dependence that is marked
203 /// as "artificial", meaning it isn't necessary for correctness.
204 bool isArtificial() const {
205 return getKind() == Order && Contents.OrdKind == Artificial;
208 /// isAssignedRegDep - Test if this is a Data dependence that is
209 /// associated with a register.
210 bool isAssignedRegDep() const {
211 return getKind() == Data && Contents.Reg != 0;
214 /// getReg - Return the register associated with this edge. This is
215 /// only valid on Data, Anti, and Output edges. On Data edges, this
216 /// value may be zero, meaning there is no associated register.
217 unsigned getReg() const {
218 assert((getKind() == Data || getKind() == Anti || getKind() == Output) &&
219 "getReg called on non-register dependence edge!");
223 /// setReg - Assign the associated register for this edge. This is
224 /// only valid on Data, Anti, and Output edges. On Anti and Output
225 /// edges, this value must not be zero. On Data edges, the value may
226 /// be zero, which would mean that no specific register is associated
228 void setReg(unsigned Reg) {
229 assert((getKind() == Data || getKind() == Anti || getKind() == Output) &&
230 "setReg called on non-register dependence edge!");
231 assert((getKind() != Anti || Reg != 0) &&
232 "SDep::Anti edge cannot use the zero register!");
233 assert((getKind() != Output || Reg != 0) &&
234 "SDep::Output edge cannot use the zero register!");
240 struct isPodLike<SDep> { static const bool value = true; };
242 /// SUnit - Scheduling unit. This is a node in the scheduling DAG.
245 SDNode *Node; // Representative node.
246 MachineInstr *Instr; // Alternatively, a MachineInstr.
248 SUnit *OrigNode; // If not this, the node from which
249 // this node was cloned.
250 // (SD scheduling only)
252 // Preds/Succs - The SUnits before/after us in the graph.
253 SmallVector<SDep, 4> Preds; // All sunit predecessors.
254 SmallVector<SDep, 4> Succs; // All sunit successors.
256 typedef SmallVector<SDep, 4>::iterator pred_iterator;
257 typedef SmallVector<SDep, 4>::iterator succ_iterator;
258 typedef SmallVector<SDep, 4>::const_iterator const_pred_iterator;
259 typedef SmallVector<SDep, 4>::const_iterator const_succ_iterator;
261 unsigned NodeNum; // Entry # of node in the node vector.
262 unsigned NodeQueueId; // Queue id of node.
263 unsigned NumPreds; // # of SDep::Data preds.
264 unsigned NumSuccs; // # of SDep::Data sucss.
265 unsigned NumPredsLeft; // # of preds not scheduled.
266 unsigned NumSuccsLeft; // # of succs not scheduled.
267 unsigned short NumRegDefsLeft; // # of reg defs with no scheduled use.
268 unsigned short Latency; // Node latency.
269 bool isVRegCycle : 1; // May use and def the same vreg.
270 bool isCall : 1; // Is a function call.
271 bool isCallOp : 1; // Is a function call operand.
272 bool isTwoAddress : 1; // Is a two-address instruction.
273 bool isCommutable : 1; // Is a commutable instruction.
274 bool hasPhysRegDefs : 1; // Has physreg defs that are being used.
275 bool hasPhysRegClobbers : 1; // Has any physreg defs, used or not.
276 bool isPending : 1; // True once pending.
277 bool isAvailable : 1; // True once available.
278 bool isScheduled : 1; // True once scheduled.
279 bool isScheduleHigh : 1; // True if preferable to schedule high.
280 bool isScheduleLow : 1; // True if preferable to schedule low.
281 bool isCloned : 1; // True if this node has been cloned.
282 Sched::Preference SchedulingPref; // Scheduling preference.
285 bool isDepthCurrent : 1; // True if Depth is current.
286 bool isHeightCurrent : 1; // True if Height is current.
287 unsigned Depth; // Node depth.
288 unsigned Height; // Node height.
290 unsigned TopReadyCycle; // Cycle relative to start when node is ready.
291 unsigned BotReadyCycle; // Cycle relative to end when node is ready.
293 const TargetRegisterClass *CopyDstRC; // Is a special copy node if not null.
294 const TargetRegisterClass *CopySrcRC;
296 /// SUnit - Construct an SUnit for pre-regalloc scheduling to represent
297 /// an SDNode and any nodes flagged to it.
298 SUnit(SDNode *node, unsigned nodenum)
299 : Node(node), Instr(0), OrigNode(0), NodeNum(nodenum),
300 NodeQueueId(0), NumPreds(0), NumSuccs(0), NumPredsLeft(0),
301 NumSuccsLeft(0), NumRegDefsLeft(0), Latency(0),
302 isVRegCycle(false), isCall(false), isCallOp(false), isTwoAddress(false),
303 isCommutable(false), hasPhysRegDefs(false), hasPhysRegClobbers(false),
304 isPending(false), isAvailable(false), isScheduled(false),
305 isScheduleHigh(false), isScheduleLow(false), isCloned(false),
306 SchedulingPref(Sched::None),
307 isDepthCurrent(false), isHeightCurrent(false), Depth(0), Height(0),
308 TopReadyCycle(0), BotReadyCycle(0), CopyDstRC(NULL), CopySrcRC(NULL) {}
310 /// SUnit - Construct an SUnit for post-regalloc scheduling to represent
312 SUnit(MachineInstr *instr, unsigned nodenum)
313 : Node(0), Instr(instr), OrigNode(0), NodeNum(nodenum),
314 NodeQueueId(0), NumPreds(0), NumSuccs(0), NumPredsLeft(0),
315 NumSuccsLeft(0), NumRegDefsLeft(0), Latency(0),
316 isVRegCycle(false), isCall(false), isCallOp(false), isTwoAddress(false),
317 isCommutable(false), hasPhysRegDefs(false), hasPhysRegClobbers(false),
318 isPending(false), isAvailable(false), isScheduled(false),
319 isScheduleHigh(false), isScheduleLow(false), isCloned(false),
320 SchedulingPref(Sched::None),
321 isDepthCurrent(false), isHeightCurrent(false), Depth(0), Height(0),
322 TopReadyCycle(0), BotReadyCycle(0), CopyDstRC(NULL), CopySrcRC(NULL) {}
324 /// SUnit - Construct a placeholder SUnit.
326 : Node(0), Instr(0), OrigNode(0), NodeNum(~0u),
327 NodeQueueId(0), NumPreds(0), NumSuccs(0), NumPredsLeft(0),
328 NumSuccsLeft(0), NumRegDefsLeft(0), Latency(0),
329 isVRegCycle(false), isCall(false), isCallOp(false), isTwoAddress(false),
330 isCommutable(false), hasPhysRegDefs(false), hasPhysRegClobbers(false),
331 isPending(false), isAvailable(false), isScheduled(false),
332 isScheduleHigh(false), isScheduleLow(false), isCloned(false),
333 SchedulingPref(Sched::None),
334 isDepthCurrent(false), isHeightCurrent(false), Depth(0), Height(0),
335 TopReadyCycle(0), BotReadyCycle(0), CopyDstRC(NULL), CopySrcRC(NULL) {}
337 /// setNode - Assign the representative SDNode for this SUnit.
338 /// This may be used during pre-regalloc scheduling.
339 void setNode(SDNode *N) {
340 assert(!Instr && "Setting SDNode of SUnit with MachineInstr!");
344 /// getNode - Return the representative SDNode for this SUnit.
345 /// This may be used during pre-regalloc scheduling.
346 SDNode *getNode() const {
347 assert(!Instr && "Reading SDNode of SUnit with MachineInstr!");
351 /// isInstr - Return true if this SUnit refers to a machine instruction as
352 /// opposed to an SDNode.
353 bool isInstr() const { return Instr; }
355 /// setInstr - Assign the instruction for the SUnit.
356 /// This may be used during post-regalloc scheduling.
357 void setInstr(MachineInstr *MI) {
358 assert(!Node && "Setting MachineInstr of SUnit with SDNode!");
362 /// getInstr - Return the representative MachineInstr for this SUnit.
363 /// This may be used during post-regalloc scheduling.
364 MachineInstr *getInstr() const {
365 assert(!Node && "Reading MachineInstr of SUnit with SDNode!");
369 /// addPred - This adds the specified edge as a pred of the current node if
370 /// not already. It also adds the current node as a successor of the
372 bool addPred(const SDep &D);
374 /// removePred - This removes the specified edge as a pred of the current
375 /// node if it exists. It also removes the current node as a successor of
376 /// the specified node.
377 void removePred(const SDep &D);
379 /// getDepth - Return the depth of this node, which is the length of the
380 /// maximum path up to any node which has no predecessors.
381 unsigned getDepth() const {
383 const_cast<SUnit *>(this)->ComputeDepth();
387 /// getHeight - Return the height of this node, which is the length of the
388 /// maximum path down to any node which has no successors.
389 unsigned getHeight() const {
390 if (!isHeightCurrent)
391 const_cast<SUnit *>(this)->ComputeHeight();
395 /// setDepthToAtLeast - If NewDepth is greater than this node's
396 /// depth value, set it to be the new depth value. This also
397 /// recursively marks successor nodes dirty.
398 void setDepthToAtLeast(unsigned NewDepth);
400 /// setDepthToAtLeast - If NewDepth is greater than this node's
401 /// depth value, set it to be the new height value. This also
402 /// recursively marks predecessor nodes dirty.
403 void setHeightToAtLeast(unsigned NewHeight);
405 /// setDepthDirty - Set a flag in this node to indicate that its
406 /// stored Depth value will require recomputation the next time
407 /// getDepth() is called.
408 void setDepthDirty();
410 /// setHeightDirty - Set a flag in this node to indicate that its
411 /// stored Height value will require recomputation the next time
412 /// getHeight() is called.
413 void setHeightDirty();
415 /// isPred - Test if node N is a predecessor of this node.
416 bool isPred(SUnit *N) {
417 for (unsigned i = 0, e = (unsigned)Preds.size(); i != e; ++i)
418 if (Preds[i].getSUnit() == N)
423 /// isSucc - Test if node N is a successor of this node.
424 bool isSucc(SUnit *N) {
425 for (unsigned i = 0, e = (unsigned)Succs.size(); i != e; ++i)
426 if (Succs[i].getSUnit() == N)
431 bool isTopReady() const {
432 return NumPredsLeft == 0;
434 bool isBottomReady() const {
435 return NumSuccsLeft == 0;
438 void dump(const ScheduleDAG *G) const;
439 void dumpAll(const ScheduleDAG *G) const;
440 void print(raw_ostream &O, const ScheduleDAG *G) const;
444 void ComputeHeight();
447 //===--------------------------------------------------------------------===//
448 /// SchedulingPriorityQueue - This interface is used to plug different
449 /// priorities computation algorithms into the list scheduler. It implements
450 /// the interface of a standard priority queue, where nodes are inserted in
451 /// arbitrary order and returned in priority order. The computation of the
452 /// priority and the representation of the queue are totally up to the
453 /// implementation to decide.
455 class SchedulingPriorityQueue {
456 virtual void anchor();
460 SchedulingPriorityQueue(bool rf = false):
461 CurCycle(0), HasReadyFilter(rf) {}
462 virtual ~SchedulingPriorityQueue() {}
464 virtual bool isBottomUp() const = 0;
466 virtual void initNodes(std::vector<SUnit> &SUnits) = 0;
467 virtual void addNode(const SUnit *SU) = 0;
468 virtual void updateNode(const SUnit *SU) = 0;
469 virtual void releaseState() = 0;
471 virtual bool empty() const = 0;
473 bool hasReadyFilter() const { return HasReadyFilter; }
475 virtual bool tracksRegPressure() const { return false; }
477 virtual bool isReady(SUnit *) const {
478 assert(!HasReadyFilter && "The ready filter must override isReady()");
481 virtual void push(SUnit *U) = 0;
483 void push_all(const std::vector<SUnit *> &Nodes) {
484 for (std::vector<SUnit *>::const_iterator I = Nodes.begin(),
485 E = Nodes.end(); I != E; ++I)
489 virtual SUnit *pop() = 0;
491 virtual void remove(SUnit *SU) = 0;
493 virtual void dump(ScheduleDAG *) const {}
495 /// scheduledNode - As each node is scheduled, this method is invoked. This
496 /// allows the priority function to adjust the priority of related
497 /// unscheduled nodes, for example.
499 virtual void scheduledNode(SUnit *) {}
501 virtual void unscheduledNode(SUnit *) {}
503 void setCurCycle(unsigned Cycle) {
507 unsigned getCurCycle() const {
514 const TargetMachine &TM; // Target processor
515 const TargetInstrInfo *TII; // Target instruction information
516 const TargetRegisterInfo *TRI; // Target processor register info
517 MachineFunction &MF; // Machine function
518 MachineRegisterInfo &MRI; // Virtual/real register map
519 std::vector<SUnit> SUnits; // The scheduling units.
520 SUnit EntrySU; // Special node for the region entry.
521 SUnit ExitSU; // Special node for the region exit.
524 static const bool StressSched = false;
529 explicit ScheduleDAG(MachineFunction &mf);
531 virtual ~ScheduleDAG();
533 /// clearDAG - clear the DAG state (between regions).
536 /// getInstrDesc - Return the MCInstrDesc of this SUnit.
537 /// Return NULL for SDNodes without a machine opcode.
538 const MCInstrDesc *getInstrDesc(const SUnit *SU) const {
539 if (SU->isInstr()) return &SU->getInstr()->getDesc();
540 return getNodeDesc(SU->getNode());
543 /// viewGraph - Pop up a GraphViz/gv window with the ScheduleDAG rendered
546 void viewGraph(const Twine &Name, const Twine &Title);
549 virtual void dumpNode(const SUnit *SU) const = 0;
551 /// getGraphNodeLabel - Return a label for an SUnit node in a visualization
552 /// of the ScheduleDAG.
553 virtual std::string getGraphNodeLabel(const SUnit *SU) const = 0;
555 /// getDAGLabel - Return a label for the region of code covered by the DAG.
556 virtual std::string getDAGName() const = 0;
558 /// addCustomGraphFeatures - Add custom features for a visualization of
560 virtual void addCustomGraphFeatures(GraphWriter<ScheduleDAG*> &) const {}
563 /// VerifyScheduledDAG - Verify that all SUnits were scheduled and that
564 /// their state is consistent. Return the number of scheduled SUnits.
565 unsigned VerifyScheduledDAG(bool isBottomUp);
569 // Return the MCInstrDesc of this SDNode or NULL.
570 const MCInstrDesc *getNodeDesc(const SDNode *Node) const;
573 class SUnitIterator : public std::iterator<std::forward_iterator_tag,
578 SUnitIterator(SUnit *N, unsigned Op) : Node(N), Operand(Op) {}
580 bool operator==(const SUnitIterator& x) const {
581 return Operand == x.Operand;
583 bool operator!=(const SUnitIterator& x) const { return !operator==(x); }
585 const SUnitIterator &operator=(const SUnitIterator &I) {
586 assert(I.Node==Node && "Cannot assign iterators to two different nodes!");
591 pointer operator*() const {
592 return Node->Preds[Operand].getSUnit();
594 pointer operator->() const { return operator*(); }
596 SUnitIterator& operator++() { // Preincrement
600 SUnitIterator operator++(int) { // Postincrement
601 SUnitIterator tmp = *this; ++*this; return tmp;
604 static SUnitIterator begin(SUnit *N) { return SUnitIterator(N, 0); }
605 static SUnitIterator end (SUnit *N) {
606 return SUnitIterator(N, (unsigned)N->Preds.size());
609 unsigned getOperand() const { return Operand; }
610 const SUnit *getNode() const { return Node; }
611 /// isCtrlDep - Test if this is not an SDep::Data dependence.
612 bool isCtrlDep() const {
613 return getSDep().isCtrl();
615 bool isArtificialDep() const {
616 return getSDep().isArtificial();
618 const SDep &getSDep() const {
619 return Node->Preds[Operand];
623 template <> struct GraphTraits<SUnit*> {
624 typedef SUnit NodeType;
625 typedef SUnitIterator ChildIteratorType;
626 static inline NodeType *getEntryNode(SUnit *N) { return N; }
627 static inline ChildIteratorType child_begin(NodeType *N) {
628 return SUnitIterator::begin(N);
630 static inline ChildIteratorType child_end(NodeType *N) {
631 return SUnitIterator::end(N);
635 template <> struct GraphTraits<ScheduleDAG*> : public GraphTraits<SUnit*> {
636 typedef std::vector<SUnit>::iterator nodes_iterator;
637 static nodes_iterator nodes_begin(ScheduleDAG *G) {
638 return G->SUnits.begin();
640 static nodes_iterator nodes_end(ScheduleDAG *G) {
641 return G->SUnits.end();
645 /// ScheduleDAGTopologicalSort is a class that computes a topological
646 /// ordering for SUnits and provides methods for dynamically updating
647 /// the ordering as new edges are added.
649 /// This allows a very fast implementation of IsReachable, for example.
651 class ScheduleDAGTopologicalSort {
652 /// SUnits - A reference to the ScheduleDAG's SUnits.
653 std::vector<SUnit> &SUnits;
655 /// Index2Node - Maps topological index to the node number.
656 std::vector<int> Index2Node;
657 /// Node2Index - Maps the node number to its topological index.
658 std::vector<int> Node2Index;
659 /// Visited - a set of nodes visited during a DFS traversal.
662 /// DFS - make a DFS traversal and mark all nodes affected by the
663 /// edge insertion. These nodes will later get new topological indexes
664 /// by means of the Shift method.
665 void DFS(const SUnit *SU, int UpperBound, bool& HasLoop);
667 /// Shift - reassign topological indexes for the nodes in the DAG
668 /// to preserve the topological ordering.
669 void Shift(BitVector& Visited, int LowerBound, int UpperBound);
671 /// Allocate - assign the topological index to the node n.
672 void Allocate(int n, int index);
675 explicit ScheduleDAGTopologicalSort(std::vector<SUnit> &SUnits);
677 /// InitDAGTopologicalSorting - create the initial topological
678 /// ordering from the DAG to be scheduled.
679 void InitDAGTopologicalSorting();
681 /// IsReachable - Checks if SU is reachable from TargetSU.
682 bool IsReachable(const SUnit *SU, const SUnit *TargetSU);
684 /// WillCreateCycle - Returns true if adding an edge from SU to TargetSU
685 /// will create a cycle.
686 bool WillCreateCycle(SUnit *SU, SUnit *TargetSU);
688 /// AddPred - Updates the topological ordering to accommodate an edge
689 /// to be added from SUnit X to SUnit Y.
690 void AddPred(SUnit *Y, SUnit *X);
692 /// RemovePred - Updates the topological ordering to accommodate an
693 /// an edge to be removed from the specified node N from the predecessors
694 /// of the current node M.
695 void RemovePred(SUnit *M, SUnit *N);
697 typedef std::vector<int>::iterator iterator;
698 typedef std::vector<int>::const_iterator const_iterator;
699 iterator begin() { return Index2Node.begin(); }
700 const_iterator begin() const { return Index2Node.begin(); }
701 iterator end() { return Index2Node.end(); }
702 const_iterator end() const { return Index2Node.end(); }
704 typedef std::vector<int>::reverse_iterator reverse_iterator;
705 typedef std::vector<int>::const_reverse_iterator const_reverse_iterator;
706 reverse_iterator rbegin() { return Index2Node.rbegin(); }
707 const_reverse_iterator rbegin() const { return Index2Node.rbegin(); }
708 reverse_iterator rend() { return Index2Node.rend(); }
709 const_reverse_iterator rend() const { return Index2Node.rend(); }