ScheduleDAG.h revision 54e4c36a7349e94a84773afb56eccd4ca65b49e9
1//===------- llvm/CodeGen/ScheduleDAG.h - Common Base Class------*- C++ -*-===// 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 file implements the ScheduleDAG class, which is used as the common 11// base class for instruction schedulers. 12// 13//===----------------------------------------------------------------------===// 14 15#ifndef LLVM_CODEGEN_SCHEDULEDAG_H 16#define LLVM_CODEGEN_SCHEDULEDAG_H 17 18#include "llvm/CodeGen/MachineBasicBlock.h" 19#include "llvm/ADT/DenseMap.h" 20#include "llvm/ADT/BitVector.h" 21#include "llvm/ADT/GraphTraits.h" 22#include "llvm/ADT/SmallVector.h" 23#include "llvm/ADT/PointerIntPair.h" 24 25namespace llvm { 26 struct SUnit; 27 class MachineConstantPool; 28 class MachineFunction; 29 class MachineModuleInfo; 30 class MachineRegisterInfo; 31 class MachineInstr; 32 class TargetRegisterInfo; 33 class ScheduleDAG; 34 class SelectionDAG; 35 class SDNode; 36 class TargetInstrInfo; 37 class TargetInstrDesc; 38 class TargetLowering; 39 class TargetMachine; 40 class TargetRegisterClass; 41 template<class Graph> class GraphWriter; 42 43 /// SDep - Scheduling dependency. This represents one direction of an 44 /// edge in the scheduling DAG. 45 class SDep { 46 public: 47 /// Kind - These are the different kinds of scheduling dependencies. 48 enum Kind { 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. 53 }; 54 55 private: 56 /// Dep - A pointer to the depending/depended-on SUnit, and an enum 57 /// indicating the kind of the dependency. 58 PointerIntPair<SUnit *, 2, Kind> Dep; 59 60 /// Contents - A union discriminated by the dependence kind. 61 union { 62 /// Reg - For Data, Anti, and Output dependencies, the associated 63 /// register. For Data dependencies that don't currently have a register 64 /// assigned, this is set to zero. 65 unsigned Reg; 66 67 /// Order - Additional information about Order dependencies. 68 struct { 69 /// isNormalMemory - True if both sides of the dependence 70 /// access memory in non-volatile and fully modeled ways. 71 bool isNormalMemory : 1; 72 73 /// isMustAlias - True if both sides of the dependence are known to 74 /// access the same memory. 75 bool isMustAlias : 1; 76 77 /// isArtificial - True if this is an artificial dependency, meaning 78 /// it is not necessary for program correctness, and may be safely 79 /// deleted if necessary. 80 bool isArtificial : 1; 81 } Order; 82 } Contents; 83 84 /// Latency - The time associated with this edge. Often this is just 85 /// the value of the Latency field of the predecessor, however advanced 86 /// models may provide additional information about specific edges. 87 unsigned Latency; 88 89 public: 90 /// SDep - Construct a null SDep. This is only for use by container 91 /// classes which require default constructors. SUnits may not 92 /// have null SDep edges. 93 SDep() : Dep(0, Data) {} 94 95 /// SDep - Construct an SDep with the specified values. 96 SDep(SUnit *S, Kind kind, unsigned latency = 1, unsigned Reg = 0, 97 bool isNormalMemory = false, bool isMustAlias = false, 98 bool isArtificial = false) 99 : Dep(S, kind), Contents(), Latency(latency) { 100 switch (kind) { 101 case Anti: 102 case Output: 103 assert(Reg != 0 && 104 "SDep::Anti and SDep::Output must use a non-zero Reg!"); 105 // fall through 106 case Data: 107 assert(!isMustAlias && "isMustAlias only applies with SDep::Order!"); 108 assert(!isArtificial && "isArtificial only applies with SDep::Order!"); 109 Contents.Reg = Reg; 110 break; 111 case Order: 112 assert(Reg == 0 && "Reg given for non-register dependence!"); 113 Contents.Order.isNormalMemory = isNormalMemory; 114 Contents.Order.isMustAlias = isMustAlias; 115 Contents.Order.isArtificial = isArtificial; 116 break; 117 } 118 } 119 120 bool operator==(const SDep &Other) const { 121 if (Dep != Other.Dep) return false; 122 switch (Dep.getInt()) { 123 case Data: 124 case Anti: 125 case Output: 126 return Contents.Reg == Other.Contents.Reg; 127 case Order: 128 return Contents.Order.isNormalMemory == 129 Other.Contents.Order.isNormalMemory && 130 Contents.Order.isMustAlias == Other.Contents.Order.isMustAlias && 131 Contents.Order.isArtificial == Other.Contents.Order.isArtificial; 132 } 133 assert(0 && "Invalid dependency kind!"); 134 return false; 135 } 136 137 bool operator!=(const SDep &Other) const { 138 return !operator==(Other); 139 } 140 141 /// getLatency - Return the latency value for this edge, which roughly 142 /// means the minimum number of cycles that must elapse between the 143 /// predecessor and the successor, given that they have this edge 144 /// between them. 145 unsigned getLatency() const { 146 return Latency; 147 } 148 149 //// getSUnit - Return the SUnit to which this edge points. 150 SUnit *getSUnit() const { 151 return Dep.getPointer(); 152 } 153 154 //// setSUnit - Assign the SUnit to which this edge points. 155 void setSUnit(SUnit *SU) { 156 Dep.setPointer(SU); 157 } 158 159 /// getKind - Return an enum value representing the kind of the dependence. 160 Kind getKind() const { 161 return Dep.getInt(); 162 } 163 164 /// isCtrl - Shorthand for getKind() != SDep::Data. 165 bool isCtrl() const { 166 return getKind() != Data; 167 } 168 169 /// isArtificial - Test if this is an Order dependence that is marked 170 /// as "artificial", meaning it isn't necessary for correctness. 171 bool isArtificial() const { 172 return getKind() == Order && Contents.Order.isArtificial; 173 } 174 175 /// isMustAlias - Test if this is an Order dependence that is marked 176 /// as "must alias", meaning that the SUnits at either end of the edge 177 /// have a memory dependence on a known memory location. 178 bool isMustAlias() const { 179 return getKind() == Order && Contents.Order.isMustAlias; 180 } 181 182 /// isAssignedRegDep - Test if this is a Data dependence that is 183 /// associated with a register. 184 bool isAssignedRegDep() const { 185 return getKind() == Data && Contents.Reg != 0; 186 } 187 188 /// getReg - Return the register associated with this edge. This is 189 /// only valid on Data, Anti, and Output edges. On Data edges, this 190 /// value may be zero, meaning there is no associated register. 191 unsigned getReg() const { 192 assert((getKind() == Data || getKind() == Anti || getKind() == Output) && 193 "getReg called on non-register dependence edge!"); 194 return Contents.Reg; 195 } 196 197 /// setReg - Assign the associated register for this edge. This is 198 /// only valid on Data, Anti, and Output edges. On Anti and Output 199 /// edges, this value must not be zero. On Data edges, the value may 200 /// be zero, which would mean that no specific register is associated 201 /// with this edge. 202 void setReg(unsigned Reg) { 203 assert((getKind() == Data || getKind() == Anti || getKind() == Output) && 204 "setReg called on non-register dependence edge!"); 205 assert((getKind() != Anti || Reg != 0) && 206 "SDep::Anti edge cannot use the zero register!"); 207 assert((getKind() != Output || Reg != 0) && 208 "SDep::Output edge cannot use the zero register!"); 209 Contents.Reg = Reg; 210 } 211 }; 212 213 /// SUnit - Scheduling unit. This is a node in the scheduling DAG. 214 struct SUnit { 215 private: 216 SDNode *Node; // Representative node. 217 MachineInstr *Instr; // Alternatively, a MachineInstr. 218 public: 219 SUnit *OrigNode; // If not this, the node from which 220 // this node was cloned. 221 222 // Preds/Succs - The SUnits before/after us in the graph. The boolean value 223 // is true if the edge is a token chain edge, false if it is a value edge. 224 SmallVector<SDep, 4> Preds; // All sunit predecessors. 225 SmallVector<SDep, 4> Succs; // All sunit successors. 226 227 typedef SmallVector<SDep, 4>::iterator pred_iterator; 228 typedef SmallVector<SDep, 4>::iterator succ_iterator; 229 typedef SmallVector<SDep, 4>::const_iterator const_pred_iterator; 230 typedef SmallVector<SDep, 4>::const_iterator const_succ_iterator; 231 232 unsigned NodeNum; // Entry # of node in the node vector. 233 unsigned NodeQueueId; // Queue id of node. 234 unsigned short Latency; // Node latency. 235 short NumPreds; // # of SDep::Data preds. 236 short NumSuccs; // # of SDep::Data sucss. 237 short NumPredsLeft; // # of preds not scheduled. 238 short NumSuccsLeft; // # of succs not scheduled. 239 bool isTwoAddress : 1; // Is a two-address instruction. 240 bool isCommutable : 1; // Is a commutable instruction. 241 bool hasPhysRegDefs : 1; // Has physreg defs that are being used. 242 bool isPending : 1; // True once pending. 243 bool isAvailable : 1; // True once available. 244 bool isScheduled : 1; // True once scheduled. 245 unsigned CycleBound; // Upper/lower cycle to be scheduled at. 246 unsigned Cycle; // Once scheduled, the cycle of the op. 247 unsigned Depth; // Node depth; 248 unsigned Height; // Node height; 249 const TargetRegisterClass *CopyDstRC; // Is a special copy node if not null. 250 const TargetRegisterClass *CopySrcRC; 251 252 /// SUnit - Construct an SUnit for pre-regalloc scheduling to represent 253 /// an SDNode and any nodes flagged to it. 254 SUnit(SDNode *node, unsigned nodenum) 255 : Node(node), Instr(0), OrigNode(0), NodeNum(nodenum), NodeQueueId(0), 256 Latency(0), NumPreds(0), NumSuccs(0), NumPredsLeft(0), NumSuccsLeft(0), 257 isTwoAddress(false), isCommutable(false), hasPhysRegDefs(false), 258 isPending(false), isAvailable(false), isScheduled(false), 259 CycleBound(0), Cycle(~0u), Depth(0), Height(0), 260 CopyDstRC(NULL), CopySrcRC(NULL) {} 261 262 /// SUnit - Construct an SUnit for post-regalloc scheduling to represent 263 /// a MachineInstr. 264 SUnit(MachineInstr *instr, unsigned nodenum) 265 : Node(0), Instr(instr), OrigNode(0), NodeNum(nodenum), NodeQueueId(0), 266 Latency(0), NumPreds(0), NumSuccs(0), NumPredsLeft(0), NumSuccsLeft(0), 267 isTwoAddress(false), isCommutable(false), hasPhysRegDefs(false), 268 isPending(false), isAvailable(false), isScheduled(false), 269 CycleBound(0), Cycle(~0u), Depth(0), Height(0), 270 CopyDstRC(NULL), CopySrcRC(NULL) {} 271 272 /// setNode - Assign the representative SDNode for this SUnit. 273 /// This may be used during pre-regalloc scheduling. 274 void setNode(SDNode *N) { 275 assert(!Instr && "Setting SDNode of SUnit with MachineInstr!"); 276 Node = N; 277 } 278 279 /// getNode - Return the representative SDNode for this SUnit. 280 /// This may be used during pre-regalloc scheduling. 281 SDNode *getNode() const { 282 assert(!Instr && "Reading SDNode of SUnit with MachineInstr!"); 283 return Node; 284 } 285 286 /// setInstr - Assign the instruction for the SUnit. 287 /// This may be used during post-regalloc scheduling. 288 void setInstr(MachineInstr *MI) { 289 assert(!Node && "Setting MachineInstr of SUnit with SDNode!"); 290 Instr = MI; 291 } 292 293 /// getInstr - Return the representative MachineInstr for this SUnit. 294 /// This may be used during post-regalloc scheduling. 295 MachineInstr *getInstr() const { 296 assert(!Node && "Reading MachineInstr of SUnit with SDNode!"); 297 return Instr; 298 } 299 300 /// addPred - This adds the specified edge as a pred of the current node if 301 /// not already. It also adds the current node as a successor of the 302 /// specified node. This returns true if this is a new pred. 303 bool addPred(const SDep &D) { 304 // If this node already has this depenence, don't add a redundant one. 305 for (unsigned i = 0, e = (unsigned)Preds.size(); i != e; ++i) 306 if (Preds[i] == D) 307 return false; 308 // Add a pred to this SUnit. 309 Preds.push_back(D); 310 // Now add a corresponding succ to N. 311 SDep P = D; 312 P.setSUnit(this); 313 SUnit *N = D.getSUnit(); 314 N->Succs.push_back(P); 315 // Update the bookkeeping. 316 if (D.getKind() == SDep::Data) { 317 ++NumPreds; 318 ++N->NumSuccs; 319 } 320 if (!N->isScheduled) 321 ++NumPredsLeft; 322 if (!isScheduled) 323 ++N->NumSuccsLeft; 324 return true; 325 } 326 327 /// removePred - This removes the specified edge as a pred of the current 328 /// node if it exists. It also removes the current node as a successor of 329 /// the specified node. This returns true if the edge existed and was 330 /// removed. 331 bool removePred(const SDep &D) { 332 // Find the matching predecessor. 333 for (SmallVector<SDep, 4>::iterator I = Preds.begin(), E = Preds.end(); 334 I != E; ++I) 335 if (*I == D) { 336 bool FoundSucc = false; 337 // Find the corresponding successor in N. 338 SDep P = D; 339 P.setSUnit(this); 340 SUnit *N = D.getSUnit(); 341 for (SmallVector<SDep, 4>::iterator II = N->Succs.begin(), 342 EE = N->Succs.end(); II != EE; ++II) 343 if (*II == P) { 344 FoundSucc = true; 345 N->Succs.erase(II); 346 break; 347 } 348 assert(FoundSucc && "Mismatching preds / succs lists!"); 349 Preds.erase(I); 350 // Update the bookkeeping; 351 if (D.getKind() == SDep::Data) { 352 --NumPreds; 353 --N->NumSuccs; 354 } 355 if (!N->isScheduled) 356 --NumPredsLeft; 357 if (!isScheduled) 358 --N->NumSuccsLeft; 359 return true; 360 } 361 return false; 362 } 363 364 bool isPred(SUnit *N) { 365 for (unsigned i = 0, e = (unsigned)Preds.size(); i != e; ++i) 366 if (Preds[i].getSUnit() == N) 367 return true; 368 return false; 369 } 370 371 bool isSucc(SUnit *N) { 372 for (unsigned i = 0, e = (unsigned)Succs.size(); i != e; ++i) 373 if (Succs[i].getSUnit() == N) 374 return true; 375 return false; 376 } 377 378 void dump(const ScheduleDAG *G) const; 379 void dumpAll(const ScheduleDAG *G) const; 380 void print(raw_ostream &O, const ScheduleDAG *G) const; 381 }; 382 383 //===--------------------------------------------------------------------===// 384 /// SchedulingPriorityQueue - This interface is used to plug different 385 /// priorities computation algorithms into the list scheduler. It implements 386 /// the interface of a standard priority queue, where nodes are inserted in 387 /// arbitrary order and returned in priority order. The computation of the 388 /// priority and the representation of the queue are totally up to the 389 /// implementation to decide. 390 /// 391 class SchedulingPriorityQueue { 392 public: 393 virtual ~SchedulingPriorityQueue() {} 394 395 virtual void initNodes(std::vector<SUnit> &SUnits) = 0; 396 virtual void addNode(const SUnit *SU) = 0; 397 virtual void updateNode(const SUnit *SU) = 0; 398 virtual void releaseState() = 0; 399 400 virtual unsigned size() const = 0; 401 virtual bool empty() const = 0; 402 virtual void push(SUnit *U) = 0; 403 404 virtual void push_all(const std::vector<SUnit *> &Nodes) = 0; 405 virtual SUnit *pop() = 0; 406 407 virtual void remove(SUnit *SU) = 0; 408 409 /// ScheduledNode - As each node is scheduled, this method is invoked. This 410 /// allows the priority function to adjust the priority of related 411 /// unscheduled nodes, for example. 412 /// 413 virtual void ScheduledNode(SUnit *) {} 414 415 virtual void UnscheduledNode(SUnit *) {} 416 }; 417 418 class ScheduleDAG { 419 public: 420 SelectionDAG *DAG; // DAG of the current basic block 421 MachineBasicBlock *BB; // Current basic block 422 const TargetMachine &TM; // Target processor 423 const TargetInstrInfo *TII; // Target instruction information 424 const TargetRegisterInfo *TRI; // Target processor register info 425 TargetLowering *TLI; // Target lowering info 426 MachineFunction *MF; // Machine function 427 MachineRegisterInfo &MRI; // Virtual/real register map 428 MachineConstantPool *ConstPool; // Target constant pool 429 std::vector<SUnit*> Sequence; // The schedule. Null SUnit*'s 430 // represent noop instructions. 431 std::vector<SUnit> SUnits; // The scheduling units. 432 433 ScheduleDAG(SelectionDAG *dag, MachineBasicBlock *bb, 434 const TargetMachine &tm); 435 436 virtual ~ScheduleDAG(); 437 438 /// viewGraph - Pop up a GraphViz/gv window with the ScheduleDAG rendered 439 /// using 'dot'. 440 /// 441 void viewGraph(); 442 443 /// Run - perform scheduling. 444 /// 445 void Run(); 446 447 /// BuildSchedUnits - Build SUnits and set up their Preds and Succs 448 /// to form the scheduling dependency graph. 449 /// 450 virtual void BuildSchedUnits() = 0; 451 452 /// ComputeLatency - Compute node latency. 453 /// 454 virtual void ComputeLatency(SUnit *SU) { SU->Latency = 1; } 455 456 /// CalculateDepths, CalculateHeights - Calculate node depth / height. 457 /// 458 void CalculateDepths(); 459 void CalculateHeights(); 460 461 protected: 462 /// EmitNoop - Emit a noop instruction. 463 /// 464 void EmitNoop(); 465 466 public: 467 virtual MachineBasicBlock *EmitSchedule() = 0; 468 469 void dumpSchedule() const; 470 471 /// Schedule - Order nodes according to selected style, filling 472 /// in the Sequence member. 473 /// 474 virtual void Schedule() = 0; 475 476 virtual void dumpNode(const SUnit *SU) const = 0; 477 478 /// getGraphNodeLabel - Return a label for an SUnit node in a visualization 479 /// of the ScheduleDAG. 480 virtual std::string getGraphNodeLabel(const SUnit *SU) const = 0; 481 482 /// addCustomGraphFeatures - Add custom features for a visualization of 483 /// the ScheduleDAG. 484 virtual void addCustomGraphFeatures(GraphWriter<ScheduleDAG*> &) const {} 485 486#ifndef NDEBUG 487 /// VerifySchedule - Verify that all SUnits were scheduled and that 488 /// their state is consistent. 489 void VerifySchedule(bool isBottomUp); 490#endif 491 492 protected: 493 void AddMemOperand(MachineInstr *MI, const MachineMemOperand &MO); 494 495 void EmitCrossRCCopy(SUnit *SU, DenseMap<SUnit*, unsigned> &VRBaseMap); 496 497 private: 498 /// EmitLiveInCopy - Emit a copy for a live in physical register. If the 499 /// physical register has only a single copy use, then coalesced the copy 500 /// if possible. 501 void EmitLiveInCopy(MachineBasicBlock *MBB, 502 MachineBasicBlock::iterator &InsertPos, 503 unsigned VirtReg, unsigned PhysReg, 504 const TargetRegisterClass *RC, 505 DenseMap<MachineInstr*, unsigned> &CopyRegMap); 506 507 /// EmitLiveInCopies - If this is the first basic block in the function, 508 /// and if it has live ins that need to be copied into vregs, emit the 509 /// copies into the top of the block. 510 void EmitLiveInCopies(MachineBasicBlock *MBB); 511 }; 512 513 class SUnitIterator : public forward_iterator<SUnit, ptrdiff_t> { 514 SUnit *Node; 515 unsigned Operand; 516 517 SUnitIterator(SUnit *N, unsigned Op) : Node(N), Operand(Op) {} 518 public: 519 bool operator==(const SUnitIterator& x) const { 520 return Operand == x.Operand; 521 } 522 bool operator!=(const SUnitIterator& x) const { return !operator==(x); } 523 524 const SUnitIterator &operator=(const SUnitIterator &I) { 525 assert(I.Node == Node && "Cannot assign iterators to two different nodes!"); 526 Operand = I.Operand; 527 return *this; 528 } 529 530 pointer operator*() const { 531 return Node->Preds[Operand].getSUnit(); 532 } 533 pointer operator->() const { return operator*(); } 534 535 SUnitIterator& operator++() { // Preincrement 536 ++Operand; 537 return *this; 538 } 539 SUnitIterator operator++(int) { // Postincrement 540 SUnitIterator tmp = *this; ++*this; return tmp; 541 } 542 543 static SUnitIterator begin(SUnit *N) { return SUnitIterator(N, 0); } 544 static SUnitIterator end (SUnit *N) { 545 return SUnitIterator(N, (unsigned)N->Preds.size()); 546 } 547 548 unsigned getOperand() const { return Operand; } 549 const SUnit *getNode() const { return Node; } 550 /// isCtrlDep - Test if this is not an SDep::Data dependence. 551 bool isCtrlDep() const { 552 return Node->Preds[Operand].isCtrl(); 553 } 554 bool isArtificialDep() const { 555 return Node->Preds[Operand].isArtificial(); 556 } 557 }; 558 559 template <> struct GraphTraits<SUnit*> { 560 typedef SUnit NodeType; 561 typedef SUnitIterator ChildIteratorType; 562 static inline NodeType *getEntryNode(SUnit *N) { return N; } 563 static inline ChildIteratorType child_begin(NodeType *N) { 564 return SUnitIterator::begin(N); 565 } 566 static inline ChildIteratorType child_end(NodeType *N) { 567 return SUnitIterator::end(N); 568 } 569 }; 570 571 template <> struct GraphTraits<ScheduleDAG*> : public GraphTraits<SUnit*> { 572 typedef std::vector<SUnit>::iterator nodes_iterator; 573 static nodes_iterator nodes_begin(ScheduleDAG *G) { 574 return G->SUnits.begin(); 575 } 576 static nodes_iterator nodes_end(ScheduleDAG *G) { 577 return G->SUnits.end(); 578 } 579 }; 580 581 /// ScheduleDAGTopologicalSort is a class that computes a topological 582 /// ordering for SUnits and provides methods for dynamically updating 583 /// the ordering as new edges are added. 584 /// 585 /// This allows a very fast implementation of IsReachable, for example. 586 /// 587 class ScheduleDAGTopologicalSort { 588 /// SUnits - A reference to the ScheduleDAG's SUnits. 589 std::vector<SUnit> &SUnits; 590 591 /// Index2Node - Maps topological index to the node number. 592 std::vector<int> Index2Node; 593 /// Node2Index - Maps the node number to its topological index. 594 std::vector<int> Node2Index; 595 /// Visited - a set of nodes visited during a DFS traversal. 596 BitVector Visited; 597 598 /// DFS - make a DFS traversal and mark all nodes affected by the 599 /// edge insertion. These nodes will later get new topological indexes 600 /// by means of the Shift method. 601 void DFS(const SUnit *SU, int UpperBound, bool& HasLoop); 602 603 /// Shift - reassign topological indexes for the nodes in the DAG 604 /// to preserve the topological ordering. 605 void Shift(BitVector& Visited, int LowerBound, int UpperBound); 606 607 /// Allocate - assign the topological index to the node n. 608 void Allocate(int n, int index); 609 610 public: 611 explicit ScheduleDAGTopologicalSort(std::vector<SUnit> &SUnits); 612 613 /// InitDAGTopologicalSorting - create the initial topological 614 /// ordering from the DAG to be scheduled. 615 void InitDAGTopologicalSorting(); 616 617 /// IsReachable - Checks if SU is reachable from TargetSU. 618 bool IsReachable(const SUnit *SU, const SUnit *TargetSU); 619 620 /// WillCreateCycle - Returns true if adding an edge from SU to TargetSU 621 /// will create a cycle. 622 bool WillCreateCycle(SUnit *SU, SUnit *TargetSU); 623 624 /// AddPred - Updates the topological ordering to accomodate an edge 625 /// to be added from SUnit X to SUnit Y. 626 void AddPred(SUnit *Y, SUnit *X); 627 628 /// RemovePred - Updates the topological ordering to accomodate an 629 /// an edge to be removed from the specified node N from the predecessors 630 /// of the current node M. 631 void RemovePred(SUnit *M, SUnit *N); 632 633 typedef std::vector<int>::iterator iterator; 634 typedef std::vector<int>::const_iterator const_iterator; 635 iterator begin() { return Index2Node.begin(); } 636 const_iterator begin() const { return Index2Node.begin(); } 637 iterator end() { return Index2Node.end(); } 638 const_iterator end() const { return Index2Node.end(); } 639 640 typedef std::vector<int>::reverse_iterator reverse_iterator; 641 typedef std::vector<int>::const_reverse_iterator const_reverse_iterator; 642 reverse_iterator rbegin() { return Index2Node.rbegin(); } 643 const_reverse_iterator rbegin() const { return Index2Node.rbegin(); } 644 reverse_iterator rend() { return Index2Node.rend(); } 645 const_reverse_iterator rend() const { return Index2Node.rend(); } 646 }; 647} 648 649#endif 650