1 //===----- ScheduleDAGList.cpp - Reg pressure reduction list scheduler ----===//
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 register pressure reduction list
11 // schedulers, using standard algorithms. The basic approach uses a priority
12 // queue of available nodes to schedule. One at a time, nodes are taken from
13 // the priority queue (thus in priority order), checked for legality to
14 // schedule, and emitted if legal.
16 //===----------------------------------------------------------------------===//
18 #define DEBUG_TYPE "sched"
19 #include "llvm/CodeGen/ScheduleDAG.h"
20 #include "llvm/CodeGen/SchedulerRegistry.h"
21 #include "llvm/CodeGen/SSARegMap.h"
22 #include "llvm/Target/MRegisterInfo.h"
23 #include "llvm/Target/TargetData.h"
24 #include "llvm/Target/TargetMachine.h"
25 #include "llvm/Target/TargetInstrInfo.h"
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/Compiler.h"
28 #include "llvm/ADT/Statistic.h"
31 #include "llvm/Support/CommandLine.h"
34 static RegisterScheduler
35 burrListDAGScheduler("list-burr",
36 " Bottom-up register reduction list scheduling",
37 createBURRListDAGScheduler);
38 static RegisterScheduler
39 tdrListrDAGScheduler("list-tdrr",
40 " Top-down register reduction list scheduling",
41 createTDRRListDAGScheduler);
44 //===----------------------------------------------------------------------===//
45 /// ScheduleDAGRRList - The actual register reduction list scheduler
46 /// implementation. This supports both top-down and bottom-up scheduling.
49 class VISIBILITY_HIDDEN ScheduleDAGRRList : public ScheduleDAG {
51 /// isBottomUp - This is true if the scheduling problem is bottom-up, false if
55 /// AvailableQueue - The priority queue to use for the available SUnits.
57 SchedulingPriorityQueue *AvailableQueue;
60 ScheduleDAGRRList(SelectionDAG &dag, MachineBasicBlock *bb,
61 const TargetMachine &tm, bool isbottomup,
62 SchedulingPriorityQueue *availqueue)
63 : ScheduleDAG(dag, bb, tm), isBottomUp(isbottomup),
64 AvailableQueue(availqueue) {
67 ~ScheduleDAGRRList() {
68 delete AvailableQueue;
74 void ReleasePred(SUnit *PredSU, bool isChain, unsigned CurCycle);
75 void ReleaseSucc(SUnit *SuccSU, bool isChain, unsigned CurCycle);
76 void ScheduleNodeBottomUp(SUnit *SU, unsigned CurCycle);
77 void ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle);
78 void ListScheduleTopDown();
79 void ListScheduleBottomUp();
80 void CommuteNodesToReducePressure();
82 } // end anonymous namespace
85 /// Schedule - Schedule the DAG using list scheduling.
86 void ScheduleDAGRRList::Schedule() {
87 DOUT << "********** List Scheduling **********\n";
89 // Build scheduling units.
92 DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
93 SUnits[su].dumpAll(&DAG));
97 AvailableQueue->initNodes(SUnitMap, SUnits);
99 // Execute the actual scheduling loop Top-Down or Bottom-Up as appropriate.
101 ListScheduleBottomUp();
103 ListScheduleTopDown();
105 AvailableQueue->releaseState();
107 CommuteNodesToReducePressure();
109 DOUT << "*** Final schedule ***\n";
110 DEBUG(dumpSchedule());
113 // Emit in scheduled order
117 /// CommuteNodesToReducePressure - If a node is two-address and commutable, and
118 /// it is not the last use of its first operand, add it to the CommuteSet if
119 /// possible. It will be commuted when it is translated to a MI.
120 void ScheduleDAGRRList::CommuteNodesToReducePressure() {
121 std::set<SUnit *> OperandSeen;
122 for (unsigned i = Sequence.size()-1; i != 0; --i) { // Ignore first node.
123 SUnit *SU = Sequence[i];
125 if (SU->isCommutable) {
126 unsigned Opc = SU->Node->getTargetOpcode();
127 unsigned NumRes = CountResults(SU->Node);
128 unsigned NumOps = CountOperands(SU->Node);
129 for (unsigned j = 0; j != NumOps; ++j) {
130 if (TII->getOperandConstraint(Opc, j+NumRes, TOI::TIED_TO) == -1)
133 SDNode *OpN = SU->Node->getOperand(j).Val;
134 SUnit *OpSU = SUnitMap[OpN];
135 if (OpSU && OperandSeen.count(OpSU) == 1) {
136 // Ok, so SU is not the last use of OpSU, but SU is two-address so
137 // it will clobber OpSU. Try to commute SU if no other source operands
139 bool DoCommute = true;
140 for (unsigned k = 0; k < NumOps; ++k) {
142 OpN = SU->Node->getOperand(k).Val;
143 OpSU = SUnitMap[OpN];
144 if (OpSU && OperandSeen.count(OpSU) == 1) {
151 CommuteSet.insert(SU->Node);
154 // Only look at the first use&def node for now.
159 for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
162 OperandSeen.insert(I->first);
167 //===----------------------------------------------------------------------===//
168 // Bottom-Up Scheduling
169 //===----------------------------------------------------------------------===//
171 /// ReleasePred - Decrement the NumSuccsLeft count of a predecessor. Add it to
172 /// the Available queue is the count reaches zero. Also update its cycle bound.
173 void ScheduleDAGRRList::ReleasePred(SUnit *PredSU, bool isChain,
175 // FIXME: the distance between two nodes is not always == the predecessor's
176 // latency. For example, the reader can very well read the register written
177 // by the predecessor later than the issue cycle. It also depends on the
178 // interrupt model (drain vs. freeze).
179 PredSU->CycleBound = std::max(PredSU->CycleBound, CurCycle + PredSU->Latency);
182 PredSU->NumSuccsLeft--;
184 PredSU->NumChainSuccsLeft--;
187 if (PredSU->NumSuccsLeft < 0 || PredSU->NumChainSuccsLeft < 0) {
188 cerr << "*** List scheduling failed! ***\n";
190 cerr << " has been released too many times!\n";
195 if ((PredSU->NumSuccsLeft + PredSU->NumChainSuccsLeft) == 0) {
196 // EntryToken has to go last! Special case it here.
197 if (PredSU->Node->getOpcode() != ISD::EntryToken) {
198 PredSU->isAvailable = true;
199 AvailableQueue->push(PredSU);
204 /// ScheduleNodeBottomUp - Add the node to the schedule. Decrement the pending
205 /// count of its predecessors. If a predecessor pending count is zero, add it to
206 /// the Available queue.
207 void ScheduleDAGRRList::ScheduleNodeBottomUp(SUnit *SU, unsigned CurCycle) {
208 DOUT << "*** Scheduling [" << CurCycle << "]: ";
209 DEBUG(SU->dump(&DAG));
210 SU->Cycle = CurCycle;
212 AvailableQueue->ScheduledNode(SU);
213 Sequence.push_back(SU);
215 // Bottom up: release predecessors
216 for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
218 ReleasePred(I->first, I->second, CurCycle);
219 SU->isScheduled = true;
222 /// isReady - True if node's lower cycle bound is less or equal to the current
223 /// scheduling cycle. Always true if all nodes have uniform latency 1.
224 static inline bool isReady(SUnit *SU, unsigned CurCycle) {
225 return SU->CycleBound <= CurCycle;
228 /// ListScheduleBottomUp - The main loop of list scheduling for bottom-up
230 void ScheduleDAGRRList::ListScheduleBottomUp() {
231 unsigned CurCycle = 0;
232 // Add root to Available queue.
233 AvailableQueue->push(SUnitMap[DAG.getRoot().Val]);
235 // While Available queue is not empty, grab the node with the highest
236 // priority. If it is not ready put it back. Schedule the node.
237 std::vector<SUnit*> NotReady;
238 while (!AvailableQueue->empty()) {
239 SUnit *CurNode = AvailableQueue->pop();
240 while (CurNode && !isReady(CurNode, CurCycle)) {
241 NotReady.push_back(CurNode);
242 CurNode = AvailableQueue->pop();
245 // Add the nodes that aren't ready back onto the available list.
246 AvailableQueue->push_all(NotReady);
250 ScheduleNodeBottomUp(CurNode, CurCycle);
254 // Add entry node last
255 if (DAG.getEntryNode().Val != DAG.getRoot().Val) {
256 SUnit *Entry = SUnitMap[DAG.getEntryNode().Val];
257 Sequence.push_back(Entry);
260 // Reverse the order if it is bottom up.
261 std::reverse(Sequence.begin(), Sequence.end());
265 // Verify that all SUnits were scheduled.
266 bool AnyNotSched = false;
267 for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
268 if (SUnits[i].NumSuccsLeft != 0 || SUnits[i].NumChainSuccsLeft != 0) {
270 cerr << "*** List scheduling failed! ***\n";
271 SUnits[i].dump(&DAG);
272 cerr << "has not been scheduled!\n";
276 assert(!AnyNotSched);
280 //===----------------------------------------------------------------------===//
281 // Top-Down Scheduling
282 //===----------------------------------------------------------------------===//
284 /// ReleaseSucc - Decrement the NumPredsLeft count of a successor. Add it to
285 /// the PendingQueue if the count reaches zero.
286 void ScheduleDAGRRList::ReleaseSucc(SUnit *SuccSU, bool isChain,
288 // FIXME: the distance between two nodes is not always == the predecessor's
289 // latency. For example, the reader can very well read the register written
290 // by the predecessor later than the issue cycle. It also depends on the
291 // interrupt model (drain vs. freeze).
292 SuccSU->CycleBound = std::max(SuccSU->CycleBound, CurCycle + SuccSU->Latency);
295 SuccSU->NumPredsLeft--;
297 SuccSU->NumChainPredsLeft--;
300 if (SuccSU->NumPredsLeft < 0 || SuccSU->NumChainPredsLeft < 0) {
301 cerr << "*** List scheduling failed! ***\n";
303 cerr << " has been released too many times!\n";
308 if ((SuccSU->NumPredsLeft + SuccSU->NumChainPredsLeft) == 0) {
309 SuccSU->isAvailable = true;
310 AvailableQueue->push(SuccSU);
315 /// ScheduleNodeTopDown - Add the node to the schedule. Decrement the pending
316 /// count of its successors. If a successor pending count is zero, add it to
317 /// the Available queue.
318 void ScheduleDAGRRList::ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle) {
319 DOUT << "*** Scheduling [" << CurCycle << "]: ";
320 DEBUG(SU->dump(&DAG));
321 SU->Cycle = CurCycle;
323 AvailableQueue->ScheduledNode(SU);
324 Sequence.push_back(SU);
326 // Top down: release successors
327 for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
329 ReleaseSucc(I->first, I->second, CurCycle);
330 SU->isScheduled = true;
333 void ScheduleDAGRRList::ListScheduleTopDown() {
334 unsigned CurCycle = 0;
335 SUnit *Entry = SUnitMap[DAG.getEntryNode().Val];
337 // All leaves to Available queue.
338 for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
339 // It is available if it has no predecessors.
340 if (SUnits[i].Preds.size() == 0 && &SUnits[i] != Entry) {
341 AvailableQueue->push(&SUnits[i]);
342 SUnits[i].isAvailable = true;
346 // Emit the entry node first.
347 ScheduleNodeTopDown(Entry, CurCycle);
350 // While Available queue is not empty, grab the node with the highest
351 // priority. If it is not ready put it back. Schedule the node.
352 std::vector<SUnit*> NotReady;
353 while (!AvailableQueue->empty()) {
354 SUnit *CurNode = AvailableQueue->pop();
355 while (CurNode && !isReady(CurNode, CurCycle)) {
356 NotReady.push_back(CurNode);
357 CurNode = AvailableQueue->pop();
360 // Add the nodes that aren't ready back onto the available list.
361 AvailableQueue->push_all(NotReady);
365 ScheduleNodeTopDown(CurNode, CurCycle);
371 // Verify that all SUnits were scheduled.
372 bool AnyNotSched = false;
373 for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
374 if (!SUnits[i].isScheduled) {
376 cerr << "*** List scheduling failed! ***\n";
377 SUnits[i].dump(&DAG);
378 cerr << "has not been scheduled!\n";
382 assert(!AnyNotSched);
388 //===----------------------------------------------------------------------===//
389 // RegReductionPriorityQueue Implementation
390 //===----------------------------------------------------------------------===//
392 // This is a SchedulingPriorityQueue that schedules using Sethi Ullman numbers
393 // to reduce register pressure.
397 class RegReductionPriorityQueue;
399 /// Sorting functions for the Available queue.
400 struct bu_ls_rr_sort : public std::binary_function<SUnit*, SUnit*, bool> {
401 RegReductionPriorityQueue<bu_ls_rr_sort> *SPQ;
402 bu_ls_rr_sort(RegReductionPriorityQueue<bu_ls_rr_sort> *spq) : SPQ(spq) {}
403 bu_ls_rr_sort(const bu_ls_rr_sort &RHS) : SPQ(RHS.SPQ) {}
405 bool operator()(const SUnit* left, const SUnit* right) const;
408 struct td_ls_rr_sort : public std::binary_function<SUnit*, SUnit*, bool> {
409 RegReductionPriorityQueue<td_ls_rr_sort> *SPQ;
410 td_ls_rr_sort(RegReductionPriorityQueue<td_ls_rr_sort> *spq) : SPQ(spq) {}
411 td_ls_rr_sort(const td_ls_rr_sort &RHS) : SPQ(RHS.SPQ) {}
413 bool operator()(const SUnit* left, const SUnit* right) const;
415 } // end anonymous namespace
417 static inline bool isCopyFromLiveIn(const SUnit *SU) {
418 SDNode *N = SU->Node;
419 return N->getOpcode() == ISD::CopyFromReg &&
420 N->getOperand(N->getNumOperands()-1).getValueType() != MVT::Flag;
425 class VISIBILITY_HIDDEN RegReductionPriorityQueue
426 : public SchedulingPriorityQueue {
427 std::priority_queue<SUnit*, std::vector<SUnit*>, SF> Queue;
430 RegReductionPriorityQueue() :
433 virtual void initNodes(DenseMap<SDNode*, SUnit*> &sumap,
434 std::vector<SUnit> &sunits) {}
435 virtual void releaseState() {}
437 virtual unsigned getNodePriority(const SUnit *SU) const {
441 bool empty() const { return Queue.empty(); }
443 void push(SUnit *U) {
446 void push_all(const std::vector<SUnit *> &Nodes) {
447 for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
448 Queue.push(Nodes[i]);
452 if (empty()) return NULL;
453 SUnit *V = Queue.top();
458 virtual bool isDUOperand(const SUnit *SU1, const SUnit *SU2) {
464 class VISIBILITY_HIDDEN BURegReductionPriorityQueue
465 : public RegReductionPriorityQueue<SF> {
466 // SUnitMap SDNode to SUnit mapping (n -> 1).
467 DenseMap<SDNode*, SUnit*> *SUnitMap;
469 // SUnits - The SUnits for the current graph.
470 const std::vector<SUnit> *SUnits;
472 // SethiUllmanNumbers - The SethiUllman number for each node.
473 std::vector<unsigned> SethiUllmanNumbers;
475 const TargetInstrInfo *TII;
477 BURegReductionPriorityQueue(const TargetInstrInfo *tii)
480 void initNodes(DenseMap<SDNode*, SUnit*> &sumap,
481 std::vector<SUnit> &sunits) {
484 // Add pseudo dependency edges for two-address nodes.
485 AddPseudoTwoAddrDeps();
486 // Calculate node priorities.
487 CalculateSethiUllmanNumbers();
490 void releaseState() {
492 SethiUllmanNumbers.clear();
495 unsigned getNodePriority(const SUnit *SU) const {
496 assert(SU->NodeNum < SethiUllmanNumbers.size());
497 unsigned Opc = SU->Node->getOpcode();
498 if (Opc == ISD::CopyFromReg && !isCopyFromLiveIn(SU))
499 // CopyFromReg should be close to its def because it restricts
500 // allocation choices. But if it is a livein then perhaps we want it
501 // closer to its uses so it can be coalesced.
503 else if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
504 // CopyToReg should be close to its uses to facilitate coalescing and
507 else if (SU->NumSuccs == 0)
508 // If SU does not have a use, i.e. it doesn't produce a value that would
509 // be consumed (e.g. store), then it terminates a chain of computation.
510 // Give it a large SethiUllman number so it will be scheduled right
511 // before its predecessors that it doesn't lengthen their live ranges.
513 else if (SU->NumPreds == 0)
514 // If SU does not have a def, schedule it close to its uses because it
515 // does not lengthen any live ranges.
518 return SethiUllmanNumbers[SU->NodeNum];
521 bool isDUOperand(const SUnit *SU1, const SUnit *SU2) {
522 unsigned Opc = SU1->Node->getTargetOpcode();
523 unsigned NumRes = ScheduleDAG::CountResults(SU1->Node);
524 unsigned NumOps = ScheduleDAG::CountOperands(SU1->Node);
525 for (unsigned i = 0; i != NumOps; ++i) {
526 if (TII->getOperandConstraint(Opc, i+NumRes, TOI::TIED_TO) == -1)
528 if (SU1->Node->getOperand(i).isOperand(SU2->Node))
534 bool canClobber(SUnit *SU, SUnit *Op);
535 void AddPseudoTwoAddrDeps();
536 void CalculateSethiUllmanNumbers();
537 unsigned CalcNodeSethiUllmanNumber(const SUnit *SU);
542 class TDRegReductionPriorityQueue : public RegReductionPriorityQueue<SF> {
543 // SUnitMap SDNode to SUnit mapping (n -> 1).
544 DenseMap<SDNode*, SUnit*> *SUnitMap;
546 // SUnits - The SUnits for the current graph.
547 const std::vector<SUnit> *SUnits;
549 // SethiUllmanNumbers - The SethiUllman number for each node.
550 std::vector<unsigned> SethiUllmanNumbers;
553 TDRegReductionPriorityQueue() {}
555 void initNodes(DenseMap<SDNode*, SUnit*> &sumap,
556 std::vector<SUnit> &sunits) {
559 // Calculate node priorities.
560 CalculateSethiUllmanNumbers();
563 void releaseState() {
565 SethiUllmanNumbers.clear();
568 unsigned getNodePriority(const SUnit *SU) const {
569 assert(SU->NodeNum < SethiUllmanNumbers.size());
570 return SethiUllmanNumbers[SU->NodeNum];
574 void CalculateSethiUllmanNumbers();
575 unsigned CalcNodeSethiUllmanNumber(const SUnit *SU);
580 bool bu_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
581 bool LIsTarget = left->Node->isTargetOpcode();
582 bool RIsTarget = right->Node->isTargetOpcode();
584 // Special tie breaker: if two nodes share a operand, the one that use it
585 // as a def&use operand is preferred.
586 if (LIsTarget && RIsTarget) {
587 if (left->isTwoAddress && !right->isTwoAddress)
588 if (SPQ->isDUOperand(left, right))
590 if (!left->isTwoAddress && right->isTwoAddress)
591 if (SPQ->isDUOperand(right, left))
595 unsigned LPriority = SPQ->getNodePriority(left);
596 unsigned RPriority = SPQ->getNodePriority(right);
597 if (LPriority > RPriority)
599 else if (LPriority == RPriority)
600 if (left->Height > right->Height)
602 else if (left->Height == right->Height)
603 if (left->Depth < right->Depth)
605 else if (left->Depth == right->Depth)
606 if (left->CycleBound > right->CycleBound)
611 // FIXME: This is probably too slow!
612 static void isReachable(SUnit *SU, SUnit *TargetSU,
613 std::set<SUnit *> &Visited, bool &Reached) {
615 if (SU == TargetSU) {
619 if (!Visited.insert(SU).second) return;
621 for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end(); I != E;
623 isReachable(I->first, TargetSU, Visited, Reached);
626 static bool isReachable(SUnit *SU, SUnit *TargetSU) {
627 std::set<SUnit *> Visited;
628 bool Reached = false;
629 isReachable(SU, TargetSU, Visited, Reached);
634 bool BURegReductionPriorityQueue<SF>::canClobber(SUnit *SU, SUnit *Op) {
635 if (SU->isTwoAddress) {
636 unsigned Opc = SU->Node->getTargetOpcode();
637 unsigned NumRes = ScheduleDAG::CountResults(SU->Node);
638 unsigned NumOps = ScheduleDAG::CountOperands(SU->Node);
639 for (unsigned i = 0; i != NumOps; ++i) {
640 if (TII->getOperandConstraint(Opc, i+NumRes, TOI::TIED_TO) != -1) {
641 SDNode *DU = SU->Node->getOperand(i).Val;
642 if (Op == (*SUnitMap)[DU])
651 /// AddPseudoTwoAddrDeps - If two nodes share an operand and one of them uses
652 /// it as a def&use operand. Add a pseudo control edge from it to the other
653 /// node (if it won't create a cycle) so the two-address one will be scheduled
654 /// first (lower in the schedule).
656 void BURegReductionPriorityQueue<SF>::AddPseudoTwoAddrDeps() {
657 for (unsigned i = 0, e = SUnits->size(); i != e; ++i) {
658 SUnit *SU = (SUnit *)&((*SUnits)[i]);
659 if (!SU->isTwoAddress)
662 SDNode *Node = SU->Node;
663 if (!Node->isTargetOpcode())
666 unsigned Opc = Node->getTargetOpcode();
667 unsigned NumRes = ScheduleDAG::CountResults(Node);
668 unsigned NumOps = ScheduleDAG::CountOperands(Node);
669 for (unsigned j = 0; j != NumOps; ++j) {
670 if (TII->getOperandConstraint(Opc, j+NumRes, TOI::TIED_TO) != -1) {
671 SDNode *DU = SU->Node->getOperand(j).Val;
672 SUnit *DUSU = (*SUnitMap)[DU];
674 for (SUnit::succ_iterator I = DUSU->Succs.begin(),E = DUSU->Succs.end();
676 if (I->second) continue;
677 SUnit *SuccSU = I->first;
679 (!canClobber(SuccSU, DUSU) ||
680 (!SU->isCommutable && SuccSU->isCommutable))){
681 if (SuccSU->Depth == SU->Depth && !isReachable(SuccSU, SU)) {
682 DOUT << "Adding an edge from SU # " << SU->NodeNum
683 << " to SU #" << SuccSU->NodeNum << "\n";
684 if (SU->addPred(SuccSU, true))
685 SU->NumChainPredsLeft++;
686 if (SuccSU->addSucc(SU, true))
687 SuccSU->NumChainSuccsLeft++;
696 /// CalcNodeSethiUllmanNumber - Priority is the Sethi Ullman number.
697 /// Smaller number is the higher priority.
699 unsigned BURegReductionPriorityQueue<SF>::
700 CalcNodeSethiUllmanNumber(const SUnit *SU) {
701 unsigned &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
702 if (SethiUllmanNumber != 0)
703 return SethiUllmanNumber;
706 for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
708 if (I->second) continue; // ignore chain preds
709 SUnit *PredSU = I->first;
710 unsigned PredSethiUllman = CalcNodeSethiUllmanNumber(PredSU);
711 if (PredSethiUllman > SethiUllmanNumber) {
712 SethiUllmanNumber = PredSethiUllman;
714 } else if (PredSethiUllman == SethiUllmanNumber && !I->second)
718 SethiUllmanNumber += Extra;
720 if (SethiUllmanNumber == 0)
721 SethiUllmanNumber = 1;
723 return SethiUllmanNumber;
726 /// CalculateSethiUllmanNumbers - Calculate Sethi-Ullman numbers of all
727 /// scheduling units.
729 void BURegReductionPriorityQueue<SF>::CalculateSethiUllmanNumbers() {
730 SethiUllmanNumbers.assign(SUnits->size(), 0);
732 for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
733 CalcNodeSethiUllmanNumber(&(*SUnits)[i]);
736 static unsigned SumOfUnscheduledPredsOfSuccs(const SUnit *SU) {
738 for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
740 SUnit *SuccSU = I->first;
741 for (SUnit::const_pred_iterator II = SuccSU->Preds.begin(),
742 EE = SuccSU->Preds.end(); II != EE; ++II) {
743 SUnit *PredSU = II->first;
744 if (!PredSU->isScheduled)
754 bool td_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
755 unsigned LPriority = SPQ->getNodePriority(left);
756 unsigned RPriority = SPQ->getNodePriority(right);
757 bool LIsTarget = left->Node->isTargetOpcode();
758 bool RIsTarget = right->Node->isTargetOpcode();
759 bool LIsFloater = LIsTarget && left->NumPreds == 0;
760 bool RIsFloater = RIsTarget && right->NumPreds == 0;
761 unsigned LBonus = (SumOfUnscheduledPredsOfSuccs(left) == 1) ? 2 : 0;
762 unsigned RBonus = (SumOfUnscheduledPredsOfSuccs(right) == 1) ? 2 : 0;
764 if (left->NumSuccs == 0 && right->NumSuccs != 0)
766 else if (left->NumSuccs != 0 && right->NumSuccs == 0)
769 // Special tie breaker: if two nodes share a operand, the one that use it
770 // as a def&use operand is preferred.
771 if (LIsTarget && RIsTarget) {
772 if (left->isTwoAddress && !right->isTwoAddress) {
773 SDNode *DUNode = left->Node->getOperand(0).Val;
774 if (DUNode->isOperand(right->Node))
777 if (!left->isTwoAddress && right->isTwoAddress) {
778 SDNode *DUNode = right->Node->getOperand(0).Val;
779 if (DUNode->isOperand(left->Node))
787 if (left->NumSuccs == 1)
789 if (right->NumSuccs == 1)
792 if (LPriority+LBonus < RPriority+RBonus)
794 else if (LPriority == RPriority)
795 if (left->Depth < right->Depth)
797 else if (left->Depth == right->Depth)
798 if (left->NumSuccsLeft > right->NumSuccsLeft)
800 else if (left->NumSuccsLeft == right->NumSuccsLeft)
801 if (left->CycleBound > right->CycleBound)
806 /// CalcNodeSethiUllmanNumber - Priority is the Sethi Ullman number.
807 /// Smaller number is the higher priority.
809 unsigned TDRegReductionPriorityQueue<SF>::
810 CalcNodeSethiUllmanNumber(const SUnit *SU) {
811 unsigned &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
812 if (SethiUllmanNumber != 0)
813 return SethiUllmanNumber;
815 unsigned Opc = SU->Node->getOpcode();
816 if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
817 SethiUllmanNumber = 0xffff;
818 else if (SU->NumSuccsLeft == 0)
819 // If SU does not have a use, i.e. it doesn't produce a value that would
820 // be consumed (e.g. store), then it terminates a chain of computation.
821 // Give it a small SethiUllman number so it will be scheduled right before
822 // its predecessors that it doesn't lengthen their live ranges.
823 SethiUllmanNumber = 0;
824 else if (SU->NumPredsLeft == 0 &&
825 (Opc != ISD::CopyFromReg || isCopyFromLiveIn(SU)))
826 SethiUllmanNumber = 0xffff;
829 for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
831 if (I->second) continue; // ignore chain preds
832 SUnit *PredSU = I->first;
833 unsigned PredSethiUllman = CalcNodeSethiUllmanNumber(PredSU);
834 if (PredSethiUllman > SethiUllmanNumber) {
835 SethiUllmanNumber = PredSethiUllman;
837 } else if (PredSethiUllman == SethiUllmanNumber && !I->second)
841 SethiUllmanNumber += Extra;
844 return SethiUllmanNumber;
847 /// CalculateSethiUllmanNumbers - Calculate Sethi-Ullman numbers of all
848 /// scheduling units.
850 void TDRegReductionPriorityQueue<SF>::CalculateSethiUllmanNumbers() {
851 SethiUllmanNumbers.assign(SUnits->size(), 0);
853 for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
854 CalcNodeSethiUllmanNumber(&(*SUnits)[i]);
857 //===----------------------------------------------------------------------===//
858 // Public Constructor Functions
859 //===----------------------------------------------------------------------===//
861 llvm::ScheduleDAG* llvm::createBURRListDAGScheduler(SelectionDAGISel *IS,
863 MachineBasicBlock *BB) {
864 const TargetInstrInfo *TII = DAG->getTarget().getInstrInfo();
865 return new ScheduleDAGRRList(*DAG, BB, DAG->getTarget(), true,
866 new BURegReductionPriorityQueue<bu_ls_rr_sort>(TII));
869 llvm::ScheduleDAG* llvm::createTDRRListDAGScheduler(SelectionDAGISel *IS,
871 MachineBasicBlock *BB) {
872 return new ScheduleDAGRRList(*DAG, BB, DAG->getTarget(), false,
873 new TDRegReductionPriorityQueue<td_ls_rr_sort>());