1 //===---- ScheduleDAGList.cpp - Implement a list scheduler for isel DAG ---===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by Evan Cheng and is distributed under the
6 // University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This implements bottom-up and top-down list schedulers, using standard
11 // algorithms. The basic approach uses a priority queue of available nodes to
12 // schedule. One at a time, nodes are taken from the priority queue (thus in
13 // priority order), checked for legality to schedule, and emitted if legal.
15 // Nodes may not be legal to schedule either due to structural hazards (e.g.
16 // pipeline or resource constraints) or because an input to the instruction has
17 // not completed execution.
19 //===----------------------------------------------------------------------===//
21 #define DEBUG_TYPE "sched"
22 #include "llvm/CodeGen/ScheduleDAG.h"
23 #include "llvm/Target/TargetMachine.h"
24 #include "llvm/Target/TargetInstrInfo.h"
25 #include "llvm/Support/Debug.h"
26 #include "llvm/ADT/Statistic.h"
35 Statistic<> NumNoops ("scheduler", "Number of noops inserted");
36 Statistic<> NumStalls("scheduler", "Number of pipeline stalls");
38 /// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or
39 /// a group of nodes flagged together.
41 SDNode *Node; // Representative node.
42 std::vector<SDNode*> FlaggedNodes; // All nodes flagged to Node.
43 std::set<SUnit*> Preds; // All real predecessors.
44 std::set<SUnit*> ChainPreds; // All chain predecessors.
45 std::set<SUnit*> Succs; // All real successors.
46 std::set<SUnit*> ChainSuccs; // All chain successors.
47 short NumPredsLeft; // # of preds not scheduled.
48 short NumSuccsLeft; // # of succs not scheduled.
49 short NumChainPredsLeft; // # of chain preds not scheduled.
50 short NumChainSuccsLeft; // # of chain succs not scheduled.
51 bool isTwoAddress : 1; // Is a two-address instruction.
52 bool isDefNUseOperand : 1; // Is a def&use operand.
53 unsigned short Latency; // Node latency.
54 unsigned CycleBound; // Upper/lower cycle to be scheduled at.
55 unsigned NodeNum; // Entry # of node in the node vector.
57 SUnit(SDNode *node, unsigned nodenum)
58 : Node(node), NumPredsLeft(0), NumSuccsLeft(0),
59 NumChainPredsLeft(0), NumChainSuccsLeft(0),
60 isTwoAddress(false), isDefNUseOperand(false),
61 Latency(0), CycleBound(0), NodeNum(nodenum) {}
63 void dump(const SelectionDAG *G, bool All=true) const;
67 void SUnit::dump(const SelectionDAG *G, bool All) const {
71 if (FlaggedNodes.size() != 0) {
72 for (unsigned i = 0, e = FlaggedNodes.size(); i != e; i++) {
74 FlaggedNodes[i]->dump(G);
80 std::cerr << " # preds left : " << NumPredsLeft << "\n";
81 std::cerr << " # succs left : " << NumSuccsLeft << "\n";
82 std::cerr << " # chain preds left : " << NumChainPredsLeft << "\n";
83 std::cerr << " # chain succs left : " << NumChainSuccsLeft << "\n";
84 std::cerr << " Latency : " << Latency << "\n";
86 if (Preds.size() != 0) {
87 std::cerr << " Predecessors:\n";
88 for (std::set<SUnit*>::const_iterator I = Preds.begin(),
89 E = Preds.end(); I != E; ++I) {
94 if (ChainPreds.size() != 0) {
95 std::cerr << " Chained Preds:\n";
96 for (std::set<SUnit*>::const_iterator I = ChainPreds.begin(),
97 E = ChainPreds.end(); I != E; ++I) {
102 if (Succs.size() != 0) {
103 std::cerr << " Successors:\n";
104 for (std::set<SUnit*>::const_iterator I = Succs.begin(),
105 E = Succs.end(); I != E; ++I) {
107 (*I)->dump(G, false);
110 if (ChainSuccs.size() != 0) {
111 std::cerr << " Chained succs:\n";
112 for (std::set<SUnit*>::const_iterator I = ChainSuccs.begin(),
113 E = ChainSuccs.end(); I != E; ++I) {
115 (*I)->dump(G, false);
121 //===----------------------------------------------------------------------===//
122 /// SchedulingPriorityQueue - This interface is used to plug different
123 /// priorities computation algorithms into the list scheduler. It implements the
124 /// interface of a standard priority queue, where nodes are inserted in
125 /// arbitrary order and returned in priority order. The computation of the
126 /// priority and the representation of the queue are totally up to the
127 /// implementation to decide.
130 class SchedulingPriorityQueue {
132 virtual ~SchedulingPriorityQueue() {}
134 virtual void initNodes(const std::vector<SUnit> &SUnits) = 0;
135 virtual void releaseState() = 0;
137 virtual bool empty() const = 0;
138 virtual void push(SUnit *U) = 0;
139 virtual SUnit *pop() = 0;
146 //===----------------------------------------------------------------------===//
147 /// ScheduleDAGList - The actual list scheduler implementation. This supports
148 /// both top-down and bottom-up scheduling.
150 class ScheduleDAGList : public ScheduleDAG {
152 // SDNode to SUnit mapping (many to one).
153 std::map<SDNode*, SUnit*> SUnitMap;
154 // The schedule. Null SUnit*'s represent noop instructions.
155 std::vector<SUnit*> Sequence;
156 // Current scheduling cycle.
159 // The scheduling units.
160 std::vector<SUnit> SUnits;
162 /// isBottomUp - This is true if the scheduling problem is bottom-up, false if
166 /// PriorityQueue - The priority queue to use.
167 SchedulingPriorityQueue *PriorityQueue;
169 /// HazardRec - The hazard recognizer to use.
170 HazardRecognizer *HazardRec;
173 ScheduleDAGList(SelectionDAG &dag, MachineBasicBlock *bb,
174 const TargetMachine &tm, bool isbottomup,
175 SchedulingPriorityQueue *priorityqueue,
176 HazardRecognizer *HR)
177 : ScheduleDAG(listSchedulingBURR, dag, bb, tm),
178 CurrCycle(0), isBottomUp(isbottomup),
179 PriorityQueue(priorityqueue), HazardRec(HR) {
184 delete PriorityQueue;
192 SUnit *NewSUnit(SDNode *N);
193 void ReleasePred(SchedulingPriorityQueue &Avail,
194 SUnit *PredSU, bool isChain = false);
195 void ReleaseSucc(SchedulingPriorityQueue &Avail,
196 SUnit *SuccSU, bool isChain = false);
197 void ScheduleNodeBottomUp(SchedulingPriorityQueue &Avail, SUnit *SU);
198 void ScheduleNodeTopDown(SchedulingPriorityQueue &Avail, SUnit *SU);
199 void ListScheduleTopDown(SchedulingPriorityQueue &Available);
200 void ListScheduleBottomUp(SchedulingPriorityQueue &Available);
201 void BuildSchedUnits();
204 } // end anonymous namespace
206 HazardRecognizer::~HazardRecognizer() {}
209 /// NewSUnit - Creates a new SUnit and return a ptr to it.
210 SUnit *ScheduleDAGList::NewSUnit(SDNode *N) {
211 SUnits.push_back(SUnit(N, SUnits.size()));
212 return &SUnits.back();
215 /// ReleasePred - Decrement the NumSuccsLeft count of a predecessor. Add it to
216 /// the Available queue is the count reaches zero. Also update its cycle bound.
217 void ScheduleDAGList::ReleasePred(SchedulingPriorityQueue &Available,
218 SUnit *PredSU, bool isChain) {
219 // FIXME: the distance between two nodes is not always == the predecessor's
220 // latency. For example, the reader can very well read the register written
221 // by the predecessor later than the issue cycle. It also depends on the
222 // interrupt model (drain vs. freeze).
223 PredSU->CycleBound = std::max(PredSU->CycleBound,CurrCycle + PredSU->Latency);
226 PredSU->NumSuccsLeft--;
228 PredSU->NumChainSuccsLeft--;
231 if (PredSU->NumSuccsLeft < 0 || PredSU->NumChainSuccsLeft < 0) {
232 std::cerr << "*** List scheduling failed! ***\n";
234 std::cerr << " has been released too many times!\n";
239 if ((PredSU->NumSuccsLeft + PredSU->NumChainSuccsLeft) == 0) {
240 // EntryToken has to go last! Special case it here.
241 if (PredSU->Node->getOpcode() != ISD::EntryToken)
242 Available.push(PredSU);
246 /// ReleaseSucc - Decrement the NumPredsLeft count of a successor. Add it to
247 /// the Available queue is the count reaches zero. Also update its cycle bound.
248 void ScheduleDAGList::ReleaseSucc(SchedulingPriorityQueue &Available,
249 SUnit *SuccSU, bool isChain) {
250 // FIXME: the distance between two nodes is not always == the predecessor's
251 // latency. For example, the reader can very well read the register written
252 // by the predecessor later than the issue cycle. It also depends on the
253 // interrupt model (drain vs. freeze).
254 SuccSU->CycleBound = std::max(SuccSU->CycleBound,CurrCycle + SuccSU->Latency);
257 SuccSU->NumPredsLeft--;
259 SuccSU->NumChainPredsLeft--;
262 if (SuccSU->NumPredsLeft < 0 || SuccSU->NumChainPredsLeft < 0) {
263 std::cerr << "*** List scheduling failed! ***\n";
265 std::cerr << " has been released too many times!\n";
270 if ((SuccSU->NumPredsLeft + SuccSU->NumChainPredsLeft) == 0)
271 Available.push(SuccSU);
274 /// ScheduleNodeBottomUp - Add the node to the schedule. Decrement the pending
275 /// count of its predecessors. If a predecessor pending count is zero, add it to
276 /// the Available queue.
277 void ScheduleDAGList::ScheduleNodeBottomUp(SchedulingPriorityQueue &Available,
279 DEBUG(std::cerr << "*** Scheduling: ");
280 DEBUG(SU->dump(&DAG, false));
282 Sequence.push_back(SU);
284 // Bottom up: release predecessors
285 for (std::set<SUnit*>::iterator I1 = SU->Preds.begin(),
286 E1 = SU->Preds.end(); I1 != E1; ++I1) {
287 ReleasePred(Available, *I1);
290 for (std::set<SUnit*>::iterator I2 = SU->ChainPreds.begin(),
291 E2 = SU->ChainPreds.end(); I2 != E2; ++I2)
292 ReleasePred(Available, *I2, true);
297 /// ScheduleNodeTopDown - Add the node to the schedule. Decrement the pending
298 /// count of its successors. If a successor pending count is zero, add it to
299 /// the Available queue.
300 void ScheduleDAGList::ScheduleNodeTopDown(SchedulingPriorityQueue &Available,
302 DEBUG(std::cerr << "*** Scheduling: ");
303 DEBUG(SU->dump(&DAG, false));
305 Sequence.push_back(SU);
307 // Bottom up: release successors.
308 for (std::set<SUnit*>::iterator I1 = SU->Succs.begin(),
309 E1 = SU->Succs.end(); I1 != E1; ++I1) {
310 ReleaseSucc(Available, *I1);
313 for (std::set<SUnit*>::iterator I2 = SU->ChainSuccs.begin(),
314 E2 = SU->ChainSuccs.end(); I2 != E2; ++I2)
315 ReleaseSucc(Available, *I2, true);
320 /// isReady - True if node's lower cycle bound is less or equal to the current
321 /// scheduling cycle. Always true if all nodes have uniform latency 1.
322 static inline bool isReady(SUnit *SU, unsigned CurrCycle) {
323 return SU->CycleBound <= CurrCycle;
326 /// ListScheduleBottomUp - The main loop of list scheduling for bottom-up
328 void ScheduleDAGList::ListScheduleBottomUp(SchedulingPriorityQueue &Available) {
329 // Add root to Available queue.
330 Available.push(SUnitMap[DAG.getRoot().Val]);
332 // While Available queue is not empty, grab the node with the highest
333 // priority. If it is not ready put it back. Schedule the node.
334 std::vector<SUnit*> NotReady;
335 while (!Available.empty()) {
336 SUnit *CurrNode = Available.pop();
338 while (!isReady(CurrNode, CurrCycle)) {
339 NotReady.push_back(CurrNode);
340 CurrNode = Available.pop();
343 // Add the nodes that aren't ready back onto the available list.
344 while (!NotReady.empty()) {
345 Available.push(NotReady.back());
349 ScheduleNodeBottomUp(Available, CurrNode);
352 // Add entry node last
353 if (DAG.getEntryNode().Val != DAG.getRoot().Val) {
354 SUnit *Entry = SUnitMap[DAG.getEntryNode().Val];
355 Sequence.push_back(Entry);
358 // Reverse the order if it is bottom up.
359 std::reverse(Sequence.begin(), Sequence.end());
363 // Verify that all SUnits were scheduled.
364 bool AnyNotSched = false;
365 for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
366 if (SUnits[i].NumSuccsLeft != 0 || SUnits[i].NumChainSuccsLeft != 0) {
368 std::cerr << "*** List scheduling failed! ***\n";
369 SUnits[i].dump(&DAG);
370 std::cerr << "has not been scheduled!\n";
374 assert(!AnyNotSched);
378 /// ListScheduleTopDown - The main loop of list scheduling for top-down
380 void ScheduleDAGList::ListScheduleTopDown(SchedulingPriorityQueue &Available) {
381 // Emit the entry node first.
382 SUnit *Entry = SUnitMap[DAG.getEntryNode().Val];
383 ScheduleNodeTopDown(Available, Entry);
384 HazardRec->EmitInstruction(Entry->Node);
386 // All leaves to Available queue.
387 for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
388 // It is available if it has no predecessors.
389 if ((SUnits[i].Preds.size() + SUnits[i].ChainPreds.size()) == 0 &&
391 Available.push(&SUnits[i]);
394 // While Available queue is not empty, grab the node with the highest
395 // priority. If it is not ready put it back. Schedule the node.
396 std::vector<SUnit*> NotReady;
397 while (!Available.empty()) {
398 SUnit *FoundNode = 0;
400 bool HasNoopHazards = false;
402 SUnit *CurNode = Available.pop();
404 // Get the node represented by this SUnit.
405 SDNode *N = CurNode->Node;
406 // If this is a pseudo op, like copyfromreg, look to see if there is a
407 // real target node flagged to it. If so, use the target node.
408 for (unsigned i = 0, e = CurNode->FlaggedNodes.size();
409 N->getOpcode() < ISD::BUILTIN_OP_END && i != e; ++i)
410 N = CurNode->FlaggedNodes[i];
412 HazardRecognizer::HazardType HT = HazardRec->getHazardType(N);
413 if (HT == HazardRecognizer::NoHazard) {
418 // Remember if this is a noop hazard.
419 HasNoopHazards |= HT == HazardRecognizer::NoopHazard;
421 NotReady.push_back(CurNode);
422 } while (!Available.empty());
424 // Add the nodes that aren't ready back onto the available list.
425 while (!NotReady.empty()) {
426 Available.push(NotReady.back());
430 // If we found a node to schedule, do it now.
432 ScheduleNodeTopDown(Available, FoundNode);
433 HazardRec->EmitInstruction(FoundNode->Node);
434 } else if (!HasNoopHazards) {
435 // Otherwise, we have a pipeline stall, but no other problem, just advance
436 // the current cycle and try again.
437 DEBUG(std::cerr << "*** Advancing cycle, no work to do\n");
438 HazardRec->AdvanceCycle();
441 // Otherwise, we have no instructions to issue and we have instructions
442 // that will fault if we don't do this right. This is the case for
443 // processors without pipeline interlocks and other cases.
444 DEBUG(std::cerr << "*** Emitting noop\n");
445 HazardRec->EmitNoop();
446 Sequence.push_back(0); // NULL SUnit* -> noop
452 // Verify that all SUnits were scheduled.
453 bool AnyNotSched = false;
454 for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
455 if (SUnits[i].NumPredsLeft != 0 || SUnits[i].NumChainPredsLeft != 0) {
457 std::cerr << "*** List scheduling failed! ***\n";
458 SUnits[i].dump(&DAG);
459 std::cerr << "has not been scheduled!\n";
463 assert(!AnyNotSched);
468 void ScheduleDAGList::BuildSchedUnits() {
469 // Reserve entries in the vector for each of the SUnits we are creating. This
470 // ensure that reallocation of the vector won't happen, so SUnit*'s won't get
472 SUnits.reserve(NodeCount);
474 // Pass 1: create the SUnit's.
475 for (unsigned i = 0, NC = NodeCount; i < NC; i++) {
476 NodeInfo *NI = &Info[i];
477 SDNode *N = NI->Node;
478 if (isPassiveNode(N))
482 if (NI->isInGroup()) {
483 if (NI != NI->Group->getBottom()) // Bottom up, so only look at bottom
484 continue; // node of the NodeGroup
487 // Find the flagged nodes.
488 SDOperand FlagOp = N->getOperand(N->getNumOperands() - 1);
489 SDNode *Flag = FlagOp.Val;
490 unsigned ResNo = FlagOp.ResNo;
491 while (Flag->getValueType(ResNo) == MVT::Flag) {
492 NodeInfo *FNI = getNI(Flag);
493 assert(FNI->Group == NI->Group);
494 SU->FlaggedNodes.insert(SU->FlaggedNodes.begin(), Flag);
497 FlagOp = Flag->getOperand(Flag->getNumOperands() - 1);
499 ResNo = FlagOp.ResNo;
506 // FIXME: assumes uniform latency for now.
510 // Pass 2: add the preds, succs, etc.
511 for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
512 SUnit *SU = &SUnits[i];
513 SDNode *N = SU->Node;
514 NodeInfo *NI = getNI(N);
516 if (N->isTargetOpcode() && TII->isTwoAddrInstr(N->getTargetOpcode()))
517 SU->isTwoAddress = true;
519 if (NI->isInGroup()) {
520 // Find all predecessors (of the group).
521 NodeGroupOpIterator NGOI(NI);
522 while (!NGOI.isEnd()) {
523 SDOperand Op = NGOI.next();
524 SDNode *OpN = Op.Val;
525 MVT::ValueType VT = OpN->getValueType(Op.ResNo);
526 NodeInfo *OpNI = getNI(OpN);
527 if (OpNI->Group != NI->Group && !isPassiveNode(OpN)) {
528 assert(VT != MVT::Flag);
529 SUnit *OpSU = SUnitMap[OpN];
530 if (VT == MVT::Other) {
531 if (SU->ChainPreds.insert(OpSU).second)
532 SU->NumChainPredsLeft++;
533 if (OpSU->ChainSuccs.insert(SU).second)
534 OpSU->NumChainSuccsLeft++;
536 if (SU->Preds.insert(OpSU).second)
538 if (OpSU->Succs.insert(SU).second)
539 OpSU->NumSuccsLeft++;
544 // Find node predecessors.
545 for (unsigned j = 0, e = N->getNumOperands(); j != e; j++) {
546 SDOperand Op = N->getOperand(j);
547 SDNode *OpN = Op.Val;
548 MVT::ValueType VT = OpN->getValueType(Op.ResNo);
549 if (!isPassiveNode(OpN)) {
550 assert(VT != MVT::Flag);
551 SUnit *OpSU = SUnitMap[OpN];
552 if (VT == MVT::Other) {
553 if (SU->ChainPreds.insert(OpSU).second)
554 SU->NumChainPredsLeft++;
555 if (OpSU->ChainSuccs.insert(SU).second)
556 OpSU->NumChainSuccsLeft++;
558 if (SU->Preds.insert(OpSU).second)
560 if (OpSU->Succs.insert(SU).second)
561 OpSU->NumSuccsLeft++;
562 if (j == 0 && SU->isTwoAddress)
563 OpSU->isDefNUseOperand = true;
571 /// EmitSchedule - Emit the machine code in scheduled order.
572 void ScheduleDAGList::EmitSchedule() {
573 for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
574 if (SUnit *SU = Sequence[i]) {
575 for (unsigned j = 0, ee = SU->FlaggedNodes.size(); j != ee; j++) {
576 SDNode *N = SU->FlaggedNodes[j];
579 EmitNode(getNI(SU->Node));
581 // Null SUnit* is a noop.
587 /// dump - dump the schedule.
588 void ScheduleDAGList::dump() const {
589 for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
590 if (SUnit *SU = Sequence[i])
591 SU->dump(&DAG, false);
593 std::cerr << "**** NOOP ****\n";
597 /// Schedule - Schedule the DAG using list scheduling.
598 /// FIXME: Right now it only supports the burr (bottom up register reducing)
600 void ScheduleDAGList::Schedule() {
601 DEBUG(std::cerr << "********** List Scheduling **********\n");
603 // Build scheduling units.
606 PriorityQueue->initNodes(SUnits);
608 // Execute the actual scheduling loop Top-Down or Bottom-Up as appropriate.
610 ListScheduleBottomUp(*PriorityQueue);
612 ListScheduleTopDown(*PriorityQueue);
614 PriorityQueue->releaseState();
616 DEBUG(std::cerr << "*** Final schedule ***\n");
618 DEBUG(std::cerr << "\n");
620 // Emit in scheduled order
624 //===----------------------------------------------------------------------===//
625 // RegReductionPriorityQueue Implementation
626 //===----------------------------------------------------------------------===//
628 // This is a SchedulingPriorityQueue that schedules using Sethi Ullman numbers
629 // to reduce register pressure.
632 class RegReductionPriorityQueue;
634 /// Sorting functions for the Available queue.
635 struct ls_rr_sort : public std::binary_function<SUnit*, SUnit*, bool> {
636 RegReductionPriorityQueue *SPQ;
637 ls_rr_sort(RegReductionPriorityQueue *spq) : SPQ(spq) {}
638 ls_rr_sort(const ls_rr_sort &RHS) : SPQ(RHS.SPQ) {}
640 bool operator()(const SUnit* left, const SUnit* right) const;
642 } // end anonymous namespace
645 class RegReductionPriorityQueue : public SchedulingPriorityQueue {
646 // SUnits - The SUnits for the current graph.
647 const std::vector<SUnit> *SUnits;
649 // SethiUllmanNumbers - The SethiUllman number for each node.
650 std::vector<int> SethiUllmanNumbers;
652 std::priority_queue<SUnit*, std::vector<SUnit*>, ls_rr_sort> Queue;
654 RegReductionPriorityQueue() : Queue(ls_rr_sort(this)) {
657 void initNodes(const std::vector<SUnit> &sunits) {
659 // Calculate node priorities.
660 CalculatePriorities();
662 void releaseState() {
664 SethiUllmanNumbers.clear();
667 unsigned getSethiUllmanNumber(unsigned NodeNum) const {
668 assert(NodeNum < SethiUllmanNumbers.size());
669 return SethiUllmanNumbers[NodeNum];
672 bool empty() const { return Queue.empty(); }
674 void push(SUnit *U) {
678 SUnit *V = Queue.top();
683 void CalculatePriorities();
684 int CalcNodePriority(const SUnit *SU);
688 bool ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
689 unsigned LeftNum = left->NodeNum;
690 unsigned RightNum = right->NodeNum;
692 int LBonus = (int)left ->isDefNUseOperand;
693 int RBonus = (int)right->isDefNUseOperand;
695 // Special tie breaker: if two nodes share a operand, the one that
696 // use it as a def&use operand is preferred.
697 if (left->isTwoAddress && !right->isTwoAddress) {
698 SDNode *DUNode = left->Node->getOperand(0).Val;
699 if (DUNode->isOperand(right->Node))
702 if (!left->isTwoAddress && right->isTwoAddress) {
703 SDNode *DUNode = right->Node->getOperand(0).Val;
704 if (DUNode->isOperand(left->Node))
708 // Priority1 is just the number of live range genned.
709 int LPriority1 = left ->NumPredsLeft - LBonus;
710 int RPriority1 = right->NumPredsLeft - RBonus;
711 int LPriority2 = SPQ->getSethiUllmanNumber(LeftNum) + LBonus;
712 int RPriority2 = SPQ->getSethiUllmanNumber(RightNum) + RBonus;
714 if (LPriority1 > RPriority1)
716 else if (LPriority1 == RPriority1)
717 if (LPriority2 < RPriority2)
719 else if (LPriority2 == RPriority2)
720 if (left->CycleBound > right->CycleBound)
727 /// CalcNodePriority - Priority is the Sethi Ullman number.
728 /// Smaller number is the higher priority.
729 int RegReductionPriorityQueue::CalcNodePriority(const SUnit *SU) {
730 int &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
731 if (SethiUllmanNumber != INT_MIN)
732 return SethiUllmanNumber;
734 if (SU->Preds.size() == 0) {
735 SethiUllmanNumber = 1;
738 for (std::set<SUnit*>::iterator I = SU->Preds.begin(),
739 E = SU->Preds.end(); I != E; ++I) {
741 int PredSethiUllman = CalcNodePriority(PredSU);
742 if (PredSethiUllman > SethiUllmanNumber) {
743 SethiUllmanNumber = PredSethiUllman;
745 } else if (PredSethiUllman == SethiUllmanNumber)
749 if (SU->Node->getOpcode() != ISD::TokenFactor)
750 SethiUllmanNumber += Extra;
752 SethiUllmanNumber = (Extra == 1) ? 0 : Extra-1;
755 return SethiUllmanNumber;
758 /// CalculatePriorities - Calculate priorities of all scheduling units.
759 void RegReductionPriorityQueue::CalculatePriorities() {
760 SethiUllmanNumbers.assign(SUnits->size(), INT_MIN);
762 for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
763 CalcNodePriority(&(*SUnits)[i]);
767 //===----------------------------------------------------------------------===//
768 // Public Constructor Functions
769 //===----------------------------------------------------------------------===//
771 llvm::ScheduleDAG* llvm::createBURRListDAGScheduler(SelectionDAG &DAG,
772 MachineBasicBlock *BB) {
773 return new ScheduleDAGList(DAG, BB, DAG.getTarget(), true,
774 new RegReductionPriorityQueue(),
775 new HazardRecognizer());
778 /// createTDListDAGScheduler - This creates a top-down list scheduler with the
779 /// specified hazard recognizer.
780 ScheduleDAG* llvm::createTDListDAGScheduler(SelectionDAG &DAG,
781 MachineBasicBlock *BB,
782 HazardRecognizer *HR) {
783 return new ScheduleDAGList(DAG, BB, DAG.getTarget(), false,
784 new RegReductionPriorityQueue(),