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);
579 /// closestSucc - Returns the scheduled cycle of the successor which is
580 /// closet to the current cycle.
581 static unsigned closestSucc(const SUnit *SU) {
582 unsigned MaxCycle = 0;
583 for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
585 unsigned Cycle = I->first->Cycle;
586 // If there are bunch of CopyToRegs stacked up, they should be considered
587 // to be at the same position.
588 if (I->first->Node->getOpcode() == ISD::CopyToReg)
589 Cycle = closestSucc(I->first)+1;
590 if (Cycle > MaxCycle)
596 /// calcMaxScratches - Returns an cost estimate of the worse case requirement
597 /// for scratch registers. Live-in operands and live-out results don't count
598 /// since they are "fixed".
599 static unsigned calcMaxScratches(const SUnit *SU) {
600 unsigned Scratches = 0;
601 for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
603 if (I->second) continue; // ignore chain preds
604 if (I->first->Node->getOpcode() != ISD::CopyFromReg)
607 for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
609 if (I->second) continue; // ignore chain succs
610 if (I->first->Node->getOpcode() != ISD::CopyToReg)
617 bool bu_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
618 bool LIsTarget = left->Node->isTargetOpcode();
619 bool RIsTarget = right->Node->isTargetOpcode();
621 // Special tie breaker: if two nodes share a operand, the one that use it
622 // as a def&use operand is preferred.
623 if (LIsTarget && RIsTarget) {
624 if (left->isTwoAddress && !right->isTwoAddress)
625 if (SPQ->isDUOperand(left, right))
627 if (!left->isTwoAddress && right->isTwoAddress)
628 if (SPQ->isDUOperand(right, left))
632 unsigned LPriority = SPQ->getNodePriority(left);
633 unsigned RPriority = SPQ->getNodePriority(right);
634 if (LPriority > RPriority)
636 else if (LPriority == RPriority) {
637 // Try schedule def + use closer when Sethi-Ullman numbers are the same.
642 // and the following instructions are both ready.
646 // Then schedule t2 = op first.
653 // This creates more short live intervals.
654 unsigned LDist = closestSucc(left);
655 unsigned RDist = closestSucc(right);
658 else if (LDist == RDist) {
659 // Intuitively, it's good to push down instructions whose results are
660 // liveout so their long live ranges won't conflict with other values
661 // which are needed inside the BB. Further prioritize liveout instructions
662 // by the number of operands which are calculated within the BB.
663 unsigned LScratch = calcMaxScratches(left);
664 unsigned RScratch = calcMaxScratches(right);
665 if (LScratch > RScratch)
667 else if (LScratch == RScratch)
668 if (left->Height > right->Height)
670 else if (left->Height == right->Height)
671 if (left->Depth < right->Depth)
673 else if (left->Depth == right->Depth)
674 if (left->CycleBound > right->CycleBound)
681 // FIXME: This is probably too slow!
682 static void isReachable(SUnit *SU, SUnit *TargetSU,
683 std::set<SUnit *> &Visited, bool &Reached) {
685 if (SU == TargetSU) {
689 if (!Visited.insert(SU).second) return;
691 for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end(); I != E;
693 isReachable(I->first, TargetSU, Visited, Reached);
696 static bool isReachable(SUnit *SU, SUnit *TargetSU) {
697 std::set<SUnit *> Visited;
698 bool Reached = false;
699 isReachable(SU, TargetSU, Visited, Reached);
704 bool BURegReductionPriorityQueue<SF>::canClobber(SUnit *SU, SUnit *Op) {
705 if (SU->isTwoAddress) {
706 unsigned Opc = SU->Node->getTargetOpcode();
707 unsigned NumRes = ScheduleDAG::CountResults(SU->Node);
708 unsigned NumOps = ScheduleDAG::CountOperands(SU->Node);
709 for (unsigned i = 0; i != NumOps; ++i) {
710 if (TII->getOperandConstraint(Opc, i+NumRes, TOI::TIED_TO) != -1) {
711 SDNode *DU = SU->Node->getOperand(i).Val;
712 if (Op == (*SUnitMap)[DU])
721 /// AddPseudoTwoAddrDeps - If two nodes share an operand and one of them uses
722 /// it as a def&use operand. Add a pseudo control edge from it to the other
723 /// node (if it won't create a cycle) so the two-address one will be scheduled
724 /// first (lower in the schedule).
726 void BURegReductionPriorityQueue<SF>::AddPseudoTwoAddrDeps() {
727 for (unsigned i = 0, e = SUnits->size(); i != e; ++i) {
728 SUnit *SU = (SUnit *)&((*SUnits)[i]);
729 if (!SU->isTwoAddress)
732 SDNode *Node = SU->Node;
733 if (!Node->isTargetOpcode())
736 unsigned Opc = Node->getTargetOpcode();
737 unsigned NumRes = ScheduleDAG::CountResults(Node);
738 unsigned NumOps = ScheduleDAG::CountOperands(Node);
739 for (unsigned j = 0; j != NumOps; ++j) {
740 if (TII->getOperandConstraint(Opc, j+NumRes, TOI::TIED_TO) != -1) {
741 SDNode *DU = SU->Node->getOperand(j).Val;
742 SUnit *DUSU = (*SUnitMap)[DU];
744 for (SUnit::succ_iterator I = DUSU->Succs.begin(),E = DUSU->Succs.end();
746 if (I->second) continue;
747 SUnit *SuccSU = I->first;
749 (!canClobber(SuccSU, DUSU) ||
750 (!SU->isCommutable && SuccSU->isCommutable))){
751 if (SuccSU->Depth == SU->Depth && !isReachable(SuccSU, SU)) {
752 DOUT << "Adding an edge from SU # " << SU->NodeNum
753 << " to SU #" << SuccSU->NodeNum << "\n";
754 if (SU->addPred(SuccSU, true))
755 SU->NumChainPredsLeft++;
756 if (SuccSU->addSucc(SU, true))
757 SuccSU->NumChainSuccsLeft++;
766 /// CalcNodeSethiUllmanNumber - Priority is the Sethi Ullman number.
767 /// Smaller number is the higher priority.
769 unsigned BURegReductionPriorityQueue<SF>::
770 CalcNodeSethiUllmanNumber(const SUnit *SU) {
771 unsigned &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
772 if (SethiUllmanNumber != 0)
773 return SethiUllmanNumber;
776 for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
778 if (I->second) continue; // ignore chain preds
779 SUnit *PredSU = I->first;
780 unsigned PredSethiUllman = CalcNodeSethiUllmanNumber(PredSU);
781 if (PredSethiUllman > SethiUllmanNumber) {
782 SethiUllmanNumber = PredSethiUllman;
784 } else if (PredSethiUllman == SethiUllmanNumber && !I->second)
788 SethiUllmanNumber += Extra;
790 if (SethiUllmanNumber == 0)
791 SethiUllmanNumber = 1;
793 return SethiUllmanNumber;
796 /// CalculateSethiUllmanNumbers - Calculate Sethi-Ullman numbers of all
797 /// scheduling units.
799 void BURegReductionPriorityQueue<SF>::CalculateSethiUllmanNumbers() {
800 SethiUllmanNumbers.assign(SUnits->size(), 0);
802 for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
803 CalcNodeSethiUllmanNumber(&(*SUnits)[i]);
806 static unsigned SumOfUnscheduledPredsOfSuccs(const SUnit *SU) {
808 for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
810 SUnit *SuccSU = I->first;
811 for (SUnit::const_pred_iterator II = SuccSU->Preds.begin(),
812 EE = SuccSU->Preds.end(); II != EE; ++II) {
813 SUnit *PredSU = II->first;
814 if (!PredSU->isScheduled)
824 bool td_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
825 unsigned LPriority = SPQ->getNodePriority(left);
826 unsigned RPriority = SPQ->getNodePriority(right);
827 bool LIsTarget = left->Node->isTargetOpcode();
828 bool RIsTarget = right->Node->isTargetOpcode();
829 bool LIsFloater = LIsTarget && left->NumPreds == 0;
830 bool RIsFloater = RIsTarget && right->NumPreds == 0;
831 unsigned LBonus = (SumOfUnscheduledPredsOfSuccs(left) == 1) ? 2 : 0;
832 unsigned RBonus = (SumOfUnscheduledPredsOfSuccs(right) == 1) ? 2 : 0;
834 if (left->NumSuccs == 0 && right->NumSuccs != 0)
836 else if (left->NumSuccs != 0 && right->NumSuccs == 0)
839 // Special tie breaker: if two nodes share a operand, the one that use it
840 // as a def&use operand is preferred.
841 if (LIsTarget && RIsTarget) {
842 if (left->isTwoAddress && !right->isTwoAddress) {
843 SDNode *DUNode = left->Node->getOperand(0).Val;
844 if (DUNode->isOperand(right->Node))
847 if (!left->isTwoAddress && right->isTwoAddress) {
848 SDNode *DUNode = right->Node->getOperand(0).Val;
849 if (DUNode->isOperand(left->Node))
857 if (left->NumSuccs == 1)
859 if (right->NumSuccs == 1)
862 if (LPriority+LBonus < RPriority+RBonus)
864 else if (LPriority == RPriority)
865 if (left->Depth < right->Depth)
867 else if (left->Depth == right->Depth)
868 if (left->NumSuccsLeft > right->NumSuccsLeft)
870 else if (left->NumSuccsLeft == right->NumSuccsLeft)
871 if (left->CycleBound > right->CycleBound)
876 /// CalcNodeSethiUllmanNumber - Priority is the Sethi Ullman number.
877 /// Smaller number is the higher priority.
879 unsigned TDRegReductionPriorityQueue<SF>::
880 CalcNodeSethiUllmanNumber(const SUnit *SU) {
881 unsigned &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
882 if (SethiUllmanNumber != 0)
883 return SethiUllmanNumber;
885 unsigned Opc = SU->Node->getOpcode();
886 if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
887 SethiUllmanNumber = 0xffff;
888 else if (SU->NumSuccsLeft == 0)
889 // If SU does not have a use, i.e. it doesn't produce a value that would
890 // be consumed (e.g. store), then it terminates a chain of computation.
891 // Give it a small SethiUllman number so it will be scheduled right before
892 // its predecessors that it doesn't lengthen their live ranges.
893 SethiUllmanNumber = 0;
894 else if (SU->NumPredsLeft == 0 &&
895 (Opc != ISD::CopyFromReg || isCopyFromLiveIn(SU)))
896 SethiUllmanNumber = 0xffff;
899 for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
901 if (I->second) continue; // ignore chain preds
902 SUnit *PredSU = I->first;
903 unsigned PredSethiUllman = CalcNodeSethiUllmanNumber(PredSU);
904 if (PredSethiUllman > SethiUllmanNumber) {
905 SethiUllmanNumber = PredSethiUllman;
907 } else if (PredSethiUllman == SethiUllmanNumber && !I->second)
911 SethiUllmanNumber += Extra;
914 return SethiUllmanNumber;
917 /// CalculateSethiUllmanNumbers - Calculate Sethi-Ullman numbers of all
918 /// scheduling units.
920 void TDRegReductionPriorityQueue<SF>::CalculateSethiUllmanNumbers() {
921 SethiUllmanNumbers.assign(SUnits->size(), 0);
923 for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
924 CalcNodeSethiUllmanNumber(&(*SUnits)[i]);
927 //===----------------------------------------------------------------------===//
928 // Public Constructor Functions
929 //===----------------------------------------------------------------------===//
931 llvm::ScheduleDAG* llvm::createBURRListDAGScheduler(SelectionDAGISel *IS,
933 MachineBasicBlock *BB) {
934 const TargetInstrInfo *TII = DAG->getTarget().getInstrInfo();
935 return new ScheduleDAGRRList(*DAG, BB, DAG->getTarget(), true,
936 new BURegReductionPriorityQueue<bu_ls_rr_sort>(TII));
939 llvm::ScheduleDAG* llvm::createTDRRListDAGScheduler(SelectionDAGISel *IS,
941 MachineBasicBlock *BB) {
942 return new ScheduleDAGRRList(*DAG, BB, DAG->getTarget(), false,
943 new TDRegReductionPriorityQueue<td_ls_rr_sort>());