1 //===- MachineScheduler.cpp - Machine Instruction Scheduler ---------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // MachineScheduler schedules machine instructions after phi elimination. It
11 // preserves LiveIntervals so it can be invoked before register allocation.
13 //===----------------------------------------------------------------------===//
15 #define DEBUG_TYPE "misched"
17 #include "llvm/CodeGen/MachineScheduler.h"
18 #include "llvm/ADT/OwningPtr.h"
19 #include "llvm/ADT/PriorityQueue.h"
20 #include "llvm/Analysis/AliasAnalysis.h"
21 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
22 #include "llvm/CodeGen/MachineDominators.h"
23 #include "llvm/CodeGen/MachineLoopInfo.h"
24 #include "llvm/CodeGen/MachineRegisterInfo.h"
25 #include "llvm/CodeGen/Passes.h"
26 #include "llvm/CodeGen/RegisterClassInfo.h"
27 #include "llvm/CodeGen/ScheduleDFS.h"
28 #include "llvm/CodeGen/ScheduleHazardRecognizer.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/Support/ErrorHandling.h"
32 #include "llvm/Support/GraphWriter.h"
33 #include "llvm/Support/raw_ostream.h"
34 #include "llvm/Target/TargetInstrInfo.h"
40 cl::opt<bool> ForceTopDown("misched-topdown", cl::Hidden,
41 cl::desc("Force top-down list scheduling"));
42 cl::opt<bool> ForceBottomUp("misched-bottomup", cl::Hidden,
43 cl::desc("Force bottom-up list scheduling"));
47 static cl::opt<bool> ViewMISchedDAGs("view-misched-dags", cl::Hidden,
48 cl::desc("Pop up a window to show MISched dags after they are processed"));
50 static cl::opt<unsigned> MISchedCutoff("misched-cutoff", cl::Hidden,
51 cl::desc("Stop scheduling after N instructions"), cl::init(~0U));
53 static bool ViewMISchedDAGs = false;
56 static cl::opt<bool> EnableLoadCluster("misched-cluster", cl::Hidden,
57 cl::desc("Enable load clustering."), cl::init(true));
59 // Experimental heuristics
60 static cl::opt<bool> EnableMacroFusion("misched-fusion", cl::Hidden,
61 cl::desc("Enable scheduling for macro fusion."), cl::init(true));
63 static cl::opt<bool> VerifyScheduling("verify-misched", cl::Hidden,
64 cl::desc("Verify machine instrs before and after machine scheduling"));
66 // DAG subtrees must have at least this many nodes.
67 static const unsigned MinSubtreeSize = 8;
69 //===----------------------------------------------------------------------===//
70 // Machine Instruction Scheduling Pass and Registry
71 //===----------------------------------------------------------------------===//
73 MachineSchedContext::MachineSchedContext():
74 MF(0), MLI(0), MDT(0), PassConfig(0), AA(0), LIS(0) {
75 RegClassInfo = new RegisterClassInfo();
78 MachineSchedContext::~MachineSchedContext() {
83 /// MachineScheduler runs after coalescing and before register allocation.
84 class MachineScheduler : public MachineSchedContext,
85 public MachineFunctionPass {
89 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
91 virtual void releaseMemory() {}
93 virtual bool runOnMachineFunction(MachineFunction&);
95 virtual void print(raw_ostream &O, const Module* = 0) const;
97 static char ID; // Class identification, replacement for typeinfo
101 char MachineScheduler::ID = 0;
103 char &llvm::MachineSchedulerID = MachineScheduler::ID;
105 INITIALIZE_PASS_BEGIN(MachineScheduler, "misched",
106 "Machine Instruction Scheduler", false, false)
107 INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
108 INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
109 INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
110 INITIALIZE_PASS_END(MachineScheduler, "misched",
111 "Machine Instruction Scheduler", false, false)
113 MachineScheduler::MachineScheduler()
114 : MachineFunctionPass(ID) {
115 initializeMachineSchedulerPass(*PassRegistry::getPassRegistry());
118 void MachineScheduler::getAnalysisUsage(AnalysisUsage &AU) const {
119 AU.setPreservesCFG();
120 AU.addRequiredID(MachineDominatorsID);
121 AU.addRequired<MachineLoopInfo>();
122 AU.addRequired<AliasAnalysis>();
123 AU.addRequired<TargetPassConfig>();
124 AU.addRequired<SlotIndexes>();
125 AU.addPreserved<SlotIndexes>();
126 AU.addRequired<LiveIntervals>();
127 AU.addPreserved<LiveIntervals>();
128 MachineFunctionPass::getAnalysisUsage(AU);
131 MachinePassRegistry MachineSchedRegistry::Registry;
133 /// A dummy default scheduler factory indicates whether the scheduler
134 /// is overridden on the command line.
135 static ScheduleDAGInstrs *useDefaultMachineSched(MachineSchedContext *C) {
139 /// MachineSchedOpt allows command line selection of the scheduler.
140 static cl::opt<MachineSchedRegistry::ScheduleDAGCtor, false,
141 RegisterPassParser<MachineSchedRegistry> >
142 MachineSchedOpt("misched",
143 cl::init(&useDefaultMachineSched), cl::Hidden,
144 cl::desc("Machine instruction scheduler to use"));
146 static MachineSchedRegistry
147 DefaultSchedRegistry("default", "Use the target's default scheduler choice.",
148 useDefaultMachineSched);
150 /// Forward declare the standard machine scheduler. This will be used as the
151 /// default scheduler if the target does not set a default.
152 static ScheduleDAGInstrs *createConvergingSched(MachineSchedContext *C);
155 /// Decrement this iterator until reaching the top or a non-debug instr.
156 static MachineBasicBlock::iterator
157 priorNonDebug(MachineBasicBlock::iterator I, MachineBasicBlock::iterator Beg) {
158 assert(I != Beg && "reached the top of the region, cannot decrement");
160 if (!I->isDebugValue())
166 /// If this iterator is a debug value, increment until reaching the End or a
167 /// non-debug instruction.
168 static MachineBasicBlock::iterator
169 nextIfDebug(MachineBasicBlock::iterator I, MachineBasicBlock::iterator End) {
170 for(; I != End; ++I) {
171 if (!I->isDebugValue())
177 /// Top-level MachineScheduler pass driver.
179 /// Visit blocks in function order. Divide each block into scheduling regions
180 /// and visit them bottom-up. Visiting regions bottom-up is not required, but is
181 /// consistent with the DAG builder, which traverses the interior of the
182 /// scheduling regions bottom-up.
184 /// This design avoids exposing scheduling boundaries to the DAG builder,
185 /// simplifying the DAG builder's support for "special" target instructions.
186 /// At the same time the design allows target schedulers to operate across
187 /// scheduling boundaries, for example to bundle the boudary instructions
188 /// without reordering them. This creates complexity, because the target
189 /// scheduler must update the RegionBegin and RegionEnd positions cached by
190 /// ScheduleDAGInstrs whenever adding or removing instructions. A much simpler
191 /// design would be to split blocks at scheduling boundaries, but LLVM has a
192 /// general bias against block splitting purely for implementation simplicity.
193 bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) {
194 DEBUG(dbgs() << "Before MISsched:\n"; mf.print(dbgs()));
196 // Initialize the context of the pass.
198 MLI = &getAnalysis<MachineLoopInfo>();
199 MDT = &getAnalysis<MachineDominatorTree>();
200 PassConfig = &getAnalysis<TargetPassConfig>();
201 AA = &getAnalysis<AliasAnalysis>();
203 LIS = &getAnalysis<LiveIntervals>();
204 const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
206 if (VerifyScheduling) {
208 MF->verify(this, "Before machine scheduling.");
210 RegClassInfo->runOnMachineFunction(*MF);
212 // Select the scheduler, or set the default.
213 MachineSchedRegistry::ScheduleDAGCtor Ctor = MachineSchedOpt;
214 if (Ctor == useDefaultMachineSched) {
215 // Get the default scheduler set by the target.
216 Ctor = MachineSchedRegistry::getDefault();
218 Ctor = createConvergingSched;
219 MachineSchedRegistry::setDefault(Ctor);
222 // Instantiate the selected scheduler.
223 OwningPtr<ScheduleDAGInstrs> Scheduler(Ctor(this));
225 // Visit all machine basic blocks.
227 // TODO: Visit blocks in global postorder or postorder within the bottom-up
228 // loop tree. Then we can optionally compute global RegPressure.
229 for (MachineFunction::iterator MBB = MF->begin(), MBBEnd = MF->end();
230 MBB != MBBEnd; ++MBB) {
232 Scheduler->startBlock(MBB);
234 // Break the block into scheduling regions [I, RegionEnd), and schedule each
235 // region as soon as it is discovered. RegionEnd points the scheduling
236 // boundary at the bottom of the region. The DAG does not include RegionEnd,
237 // but the region does (i.e. the next RegionEnd is above the previous
238 // RegionBegin). If the current block has no terminator then RegionEnd ==
239 // MBB->end() for the bottom region.
241 // The Scheduler may insert instructions during either schedule() or
242 // exitRegion(), even for empty regions. So the local iterators 'I' and
243 // 'RegionEnd' are invalid across these calls.
244 unsigned RemainingInstrs = MBB->size();
245 for(MachineBasicBlock::iterator RegionEnd = MBB->end();
246 RegionEnd != MBB->begin(); RegionEnd = Scheduler->begin()) {
248 // Avoid decrementing RegionEnd for blocks with no terminator.
249 if (RegionEnd != MBB->end()
250 || TII->isSchedulingBoundary(llvm::prior(RegionEnd), MBB, *MF)) {
252 // Count the boundary instruction.
256 // The next region starts above the previous region. Look backward in the
257 // instruction stream until we find the nearest boundary.
258 MachineBasicBlock::iterator I = RegionEnd;
259 for(;I != MBB->begin(); --I, --RemainingInstrs) {
260 if (TII->isSchedulingBoundary(llvm::prior(I), MBB, *MF))
263 // Notify the scheduler of the region, even if we may skip scheduling
264 // it. Perhaps it still needs to be bundled.
265 Scheduler->enterRegion(MBB, I, RegionEnd, RemainingInstrs);
267 // Skip empty scheduling regions (0 or 1 schedulable instructions).
268 if (I == RegionEnd || I == llvm::prior(RegionEnd)) {
269 // Close the current region. Bundle the terminator if needed.
270 // This invalidates 'RegionEnd' and 'I'.
271 Scheduler->exitRegion();
274 DEBUG(dbgs() << "********** MI Scheduling **********\n");
275 DEBUG(dbgs() << MF->getName()
276 << ":BB#" << MBB->getNumber() << " " << MBB->getName()
277 << "\n From: " << *I << " To: ";
278 if (RegionEnd != MBB->end()) dbgs() << *RegionEnd;
279 else dbgs() << "End";
280 dbgs() << " Remaining: " << RemainingInstrs << "\n");
282 // Schedule a region: possibly reorder instructions.
283 // This invalidates 'RegionEnd' and 'I'.
284 Scheduler->schedule();
286 // Close the current region.
287 Scheduler->exitRegion();
289 // Scheduling has invalidated the current iterator 'I'. Ask the
290 // scheduler for the top of it's scheduled region.
291 RegionEnd = Scheduler->begin();
293 assert(RemainingInstrs == 0 && "Instruction count mismatch!");
294 Scheduler->finishBlock();
296 Scheduler->finalizeSchedule();
298 if (VerifyScheduling)
299 MF->verify(this, "After machine scheduling.");
303 void MachineScheduler::print(raw_ostream &O, const Module* m) const {
307 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
308 void ReadyQueue::dump() {
309 dbgs() << Name << ": ";
310 for (unsigned i = 0, e = Queue.size(); i < e; ++i)
311 dbgs() << Queue[i]->NodeNum << " ";
316 //===----------------------------------------------------------------------===//
317 // ScheduleDAGMI - Base class for MachineInstr scheduling with LiveIntervals
319 //===----------------------------------------------------------------------===//
321 ScheduleDAGMI::~ScheduleDAGMI() {
323 DeleteContainerPointers(Mutations);
327 bool ScheduleDAGMI::canAddEdge(SUnit *SuccSU, SUnit *PredSU) {
328 return SuccSU == &ExitSU || !Topo.IsReachable(PredSU, SuccSU);
331 bool ScheduleDAGMI::addEdge(SUnit *SuccSU, const SDep &PredDep) {
332 if (SuccSU != &ExitSU) {
333 // Do not use WillCreateCycle, it assumes SD scheduling.
334 // If Pred is reachable from Succ, then the edge creates a cycle.
335 if (Topo.IsReachable(PredDep.getSUnit(), SuccSU))
337 Topo.AddPred(SuccSU, PredDep.getSUnit());
339 SuccSU->addPred(PredDep, /*Required=*/!PredDep.isArtificial());
340 // Return true regardless of whether a new edge needed to be inserted.
344 /// ReleaseSucc - Decrement the NumPredsLeft count of a successor. When
345 /// NumPredsLeft reaches zero, release the successor node.
347 /// FIXME: Adjust SuccSU height based on MinLatency.
348 void ScheduleDAGMI::releaseSucc(SUnit *SU, SDep *SuccEdge) {
349 SUnit *SuccSU = SuccEdge->getSUnit();
351 if (SuccEdge->isWeak()) {
352 --SuccSU->WeakPredsLeft;
353 if (SuccEdge->isCluster())
354 NextClusterSucc = SuccSU;
358 if (SuccSU->NumPredsLeft == 0) {
359 dbgs() << "*** Scheduling failed! ***\n";
361 dbgs() << " has been released too many times!\n";
365 --SuccSU->NumPredsLeft;
366 if (SuccSU->NumPredsLeft == 0 && SuccSU != &ExitSU)
367 SchedImpl->releaseTopNode(SuccSU);
370 /// releaseSuccessors - Call releaseSucc on each of SU's successors.
371 void ScheduleDAGMI::releaseSuccessors(SUnit *SU) {
372 for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
374 releaseSucc(SU, &*I);
378 /// ReleasePred - Decrement the NumSuccsLeft count of a predecessor. When
379 /// NumSuccsLeft reaches zero, release the predecessor node.
381 /// FIXME: Adjust PredSU height based on MinLatency.
382 void ScheduleDAGMI::releasePred(SUnit *SU, SDep *PredEdge) {
383 SUnit *PredSU = PredEdge->getSUnit();
385 if (PredEdge->isWeak()) {
386 --PredSU->WeakSuccsLeft;
387 if (PredEdge->isCluster())
388 NextClusterPred = PredSU;
392 if (PredSU->NumSuccsLeft == 0) {
393 dbgs() << "*** Scheduling failed! ***\n";
395 dbgs() << " has been released too many times!\n";
399 --PredSU->NumSuccsLeft;
400 if (PredSU->NumSuccsLeft == 0 && PredSU != &EntrySU)
401 SchedImpl->releaseBottomNode(PredSU);
404 /// releasePredecessors - Call releasePred on each of SU's predecessors.
405 void ScheduleDAGMI::releasePredecessors(SUnit *SU) {
406 for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
408 releasePred(SU, &*I);
412 /// This is normally called from the main scheduler loop but may also be invoked
413 /// by the scheduling strategy to perform additional code motion.
414 void ScheduleDAGMI::moveInstruction(MachineInstr *MI,
415 MachineBasicBlock::iterator InsertPos) {
416 // Advance RegionBegin if the first instruction moves down.
417 if (&*RegionBegin == MI)
420 // Update the instruction stream.
421 BB->splice(InsertPos, BB, MI);
423 // Update LiveIntervals
424 LIS->handleMove(MI, /*UpdateFlags=*/true);
426 // Recede RegionBegin if an instruction moves above the first.
427 if (RegionBegin == InsertPos)
431 bool ScheduleDAGMI::checkSchedLimit() {
433 if (NumInstrsScheduled == MISchedCutoff && MISchedCutoff != ~0U) {
434 CurrentTop = CurrentBottom;
437 ++NumInstrsScheduled;
442 /// enterRegion - Called back from MachineScheduler::runOnMachineFunction after
443 /// crossing a scheduling boundary. [begin, end) includes all instructions in
444 /// the region, including the boundary itself and single-instruction regions
445 /// that don't get scheduled.
446 void ScheduleDAGMI::enterRegion(MachineBasicBlock *bb,
447 MachineBasicBlock::iterator begin,
448 MachineBasicBlock::iterator end,
451 ScheduleDAGInstrs::enterRegion(bb, begin, end, endcount);
453 // For convenience remember the end of the liveness region.
455 (RegionEnd == bb->end()) ? RegionEnd : llvm::next(RegionEnd);
458 // Setup the register pressure trackers for the top scheduled top and bottom
459 // scheduled regions.
460 void ScheduleDAGMI::initRegPressure() {
461 TopRPTracker.init(&MF, RegClassInfo, LIS, BB, RegionBegin);
462 BotRPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd);
464 // Close the RPTracker to finalize live ins.
465 RPTracker.closeRegion();
467 DEBUG(RPTracker.getPressure().dump(TRI));
469 // Initialize the live ins and live outs.
470 TopRPTracker.addLiveRegs(RPTracker.getPressure().LiveInRegs);
471 BotRPTracker.addLiveRegs(RPTracker.getPressure().LiveOutRegs);
473 // Close one end of the tracker so we can call
474 // getMaxUpward/DownwardPressureDelta before advancing across any
475 // instructions. This converts currently live regs into live ins/outs.
476 TopRPTracker.closeTop();
477 BotRPTracker.closeBottom();
479 // Account for liveness generated by the region boundary.
480 if (LiveRegionEnd != RegionEnd)
481 BotRPTracker.recede();
483 assert(BotRPTracker.getPos() == RegionEnd && "Can't find the region bottom");
485 // Cache the list of excess pressure sets in this region. This will also track
486 // the max pressure in the scheduled code for these sets.
487 RegionCriticalPSets.clear();
488 const std::vector<unsigned> &RegionPressure =
489 RPTracker.getPressure().MaxSetPressure;
490 for (unsigned i = 0, e = RegionPressure.size(); i < e; ++i) {
491 unsigned Limit = RegClassInfo->getRegPressureSetLimit(i);
492 if (RegionPressure[i] > Limit) {
493 DEBUG(dbgs() << TRI->getRegPressureSetName(i)
494 << " Limit " << Limit
495 << " Actual " << RegionPressure[i] << "\n");
496 RegionCriticalPSets.push_back(PressureElement(i, 0));
499 DEBUG(dbgs() << "Excess PSets: ";
500 for (unsigned i = 0, e = RegionCriticalPSets.size(); i != e; ++i)
501 dbgs() << TRI->getRegPressureSetName(
502 RegionCriticalPSets[i].PSetID) << " ";
506 // FIXME: When the pressure tracker deals in pressure differences then we won't
507 // iterate over all RegionCriticalPSets[i].
509 updateScheduledPressure(const std::vector<unsigned> &NewMaxPressure) {
510 for (unsigned i = 0, e = RegionCriticalPSets.size(); i < e; ++i) {
511 unsigned ID = RegionCriticalPSets[i].PSetID;
512 int &MaxUnits = RegionCriticalPSets[i].UnitIncrease;
513 if ((int)NewMaxPressure[ID] > MaxUnits)
514 MaxUnits = NewMaxPressure[ID];
517 for (unsigned i = 0, e = NewMaxPressure.size(); i < e; ++i) {
518 unsigned Limit = RegClassInfo->getRegPressureSetLimit(i);
519 if (NewMaxPressure[i] > Limit ) {
520 dbgs() << " " << TRI->getRegPressureSetName(i) << ": "
521 << NewMaxPressure[i] << " > " << Limit << "\n";
526 /// schedule - Called back from MachineScheduler::runOnMachineFunction
527 /// after setting up the current scheduling region. [RegionBegin, RegionEnd)
528 /// only includes instructions that have DAG nodes, not scheduling boundaries.
530 /// This is a skeletal driver, with all the functionality pushed into helpers,
531 /// so that it can be easilly extended by experimental schedulers. Generally,
532 /// implementing MachineSchedStrategy should be sufficient to implement a new
533 /// scheduling algorithm. However, if a scheduler further subclasses
534 /// ScheduleDAGMI then it will want to override this virtual method in order to
535 /// update any specialized state.
536 void ScheduleDAGMI::schedule() {
537 buildDAGWithRegPressure();
539 Topo.InitDAGTopologicalSorting();
543 SmallVector<SUnit*, 8> TopRoots, BotRoots;
544 findRootsAndBiasEdges(TopRoots, BotRoots);
546 // Initialize the strategy before modifying the DAG.
547 // This may initialize a DFSResult to be used for queue priority.
548 SchedImpl->initialize(this);
550 DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
551 SUnits[su].dumpAll(this));
552 if (ViewMISchedDAGs) viewGraph();
554 // Initialize ready queues now that the DAG and priority data are finalized.
555 initQueues(TopRoots, BotRoots);
557 bool IsTopNode = false;
558 while (SUnit *SU = SchedImpl->pickNode(IsTopNode)) {
559 assert(!SU->isScheduled && "Node already scheduled");
560 if (!checkSchedLimit())
563 scheduleMI(SU, IsTopNode);
565 updateQueues(SU, IsTopNode);
567 assert(CurrentTop == CurrentBottom && "Nonempty unscheduled zone.");
572 unsigned BBNum = begin()->getParent()->getNumber();
573 dbgs() << "*** Final schedule for BB#" << BBNum << " ***\n";
579 /// Build the DAG and setup three register pressure trackers.
580 void ScheduleDAGMI::buildDAGWithRegPressure() {
581 // Initialize the register pressure tracker used by buildSchedGraph.
582 RPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd);
584 // Account for liveness generate by the region boundary.
585 if (LiveRegionEnd != RegionEnd)
588 // Build the DAG, and compute current register pressure.
589 buildSchedGraph(AA, &RPTracker);
591 // Initialize top/bottom trackers after computing region pressure.
595 /// Apply each ScheduleDAGMutation step in order.
596 void ScheduleDAGMI::postprocessDAG() {
597 for (unsigned i = 0, e = Mutations.size(); i < e; ++i) {
598 Mutations[i]->apply(this);
602 void ScheduleDAGMI::computeDFSResult() {
604 DFSResult = new SchedDFSResult(/*BottomU*/true, MinSubtreeSize);
606 ScheduledTrees.clear();
607 DFSResult->resize(SUnits.size());
608 DFSResult->compute(SUnits);
609 ScheduledTrees.resize(DFSResult->getNumSubtrees());
612 void ScheduleDAGMI::findRootsAndBiasEdges(SmallVectorImpl<SUnit*> &TopRoots,
613 SmallVectorImpl<SUnit*> &BotRoots) {
614 for (std::vector<SUnit>::iterator
615 I = SUnits.begin(), E = SUnits.end(); I != E; ++I) {
617 assert(!SU->isBoundaryNode() && "Boundary node should not be in SUnits");
619 // Order predecessors so DFSResult follows the critical path.
620 SU->biasCriticalPath();
622 // A SUnit is ready to top schedule if it has no predecessors.
623 if (!I->NumPredsLeft)
624 TopRoots.push_back(SU);
625 // A SUnit is ready to bottom schedule if it has no successors.
626 if (!I->NumSuccsLeft)
627 BotRoots.push_back(SU);
629 ExitSU.biasCriticalPath();
632 /// Identify DAG roots and setup scheduler queues.
633 void ScheduleDAGMI::initQueues(ArrayRef<SUnit*> TopRoots,
634 ArrayRef<SUnit*> BotRoots) {
635 NextClusterSucc = NULL;
636 NextClusterPred = NULL;
638 // Release all DAG roots for scheduling, not including EntrySU/ExitSU.
640 // Nodes with unreleased weak edges can still be roots.
641 // Release top roots in forward order.
642 for (SmallVectorImpl<SUnit*>::const_iterator
643 I = TopRoots.begin(), E = TopRoots.end(); I != E; ++I) {
644 SchedImpl->releaseTopNode(*I);
646 // Release bottom roots in reverse order so the higher priority nodes appear
647 // first. This is more natural and slightly more efficient.
648 for (SmallVectorImpl<SUnit*>::const_reverse_iterator
649 I = BotRoots.rbegin(), E = BotRoots.rend(); I != E; ++I) {
650 SchedImpl->releaseBottomNode(*I);
653 releaseSuccessors(&EntrySU);
654 releasePredecessors(&ExitSU);
656 SchedImpl->registerRoots();
658 // Advance past initial DebugValues.
659 assert(TopRPTracker.getPos() == RegionBegin && "bad initial Top tracker");
660 CurrentTop = nextIfDebug(RegionBegin, RegionEnd);
661 TopRPTracker.setPos(CurrentTop);
663 CurrentBottom = RegionEnd;
666 /// Move an instruction and update register pressure.
667 void ScheduleDAGMI::scheduleMI(SUnit *SU, bool IsTopNode) {
668 // Move the instruction to its new location in the instruction stream.
669 MachineInstr *MI = SU->getInstr();
672 assert(SU->isTopReady() && "node still has unscheduled dependencies");
673 if (&*CurrentTop == MI)
674 CurrentTop = nextIfDebug(++CurrentTop, CurrentBottom);
676 moveInstruction(MI, CurrentTop);
677 TopRPTracker.setPos(MI);
680 // Update top scheduled pressure.
681 TopRPTracker.advance();
682 assert(TopRPTracker.getPos() == CurrentTop && "out of sync");
683 updateScheduledPressure(TopRPTracker.getPressure().MaxSetPressure);
686 assert(SU->isBottomReady() && "node still has unscheduled dependencies");
687 MachineBasicBlock::iterator priorII =
688 priorNonDebug(CurrentBottom, CurrentTop);
690 CurrentBottom = priorII;
692 if (&*CurrentTop == MI) {
693 CurrentTop = nextIfDebug(++CurrentTop, priorII);
694 TopRPTracker.setPos(CurrentTop);
696 moveInstruction(MI, CurrentBottom);
699 // Update bottom scheduled pressure.
700 BotRPTracker.recede();
701 assert(BotRPTracker.getPos() == CurrentBottom && "out of sync");
702 updateScheduledPressure(BotRPTracker.getPressure().MaxSetPressure);
706 /// Update scheduler queues after scheduling an instruction.
707 void ScheduleDAGMI::updateQueues(SUnit *SU, bool IsTopNode) {
708 // Release dependent instructions for scheduling.
710 releaseSuccessors(SU);
712 releasePredecessors(SU);
714 SU->isScheduled = true;
717 unsigned SubtreeID = DFSResult->getSubtreeID(SU);
718 if (!ScheduledTrees.test(SubtreeID)) {
719 ScheduledTrees.set(SubtreeID);
720 DFSResult->scheduleTree(SubtreeID);
721 SchedImpl->scheduleTree(SubtreeID);
725 // Notify the scheduling strategy after updating the DAG.
726 SchedImpl->schedNode(SU, IsTopNode);
729 /// Reinsert any remaining debug_values, just like the PostRA scheduler.
730 void ScheduleDAGMI::placeDebugValues() {
731 // If first instruction was a DBG_VALUE then put it back.
733 BB->splice(RegionBegin, BB, FirstDbgValue);
734 RegionBegin = FirstDbgValue;
737 for (std::vector<std::pair<MachineInstr *, MachineInstr *> >::iterator
738 DI = DbgValues.end(), DE = DbgValues.begin(); DI != DE; --DI) {
739 std::pair<MachineInstr *, MachineInstr *> P = *prior(DI);
740 MachineInstr *DbgValue = P.first;
741 MachineBasicBlock::iterator OrigPrevMI = P.second;
742 if (&*RegionBegin == DbgValue)
744 BB->splice(++OrigPrevMI, BB, DbgValue);
745 if (OrigPrevMI == llvm::prior(RegionEnd))
746 RegionEnd = DbgValue;
749 FirstDbgValue = NULL;
752 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
753 void ScheduleDAGMI::dumpSchedule() const {
754 for (MachineBasicBlock::iterator MI = begin(), ME = end(); MI != ME; ++MI) {
755 if (SUnit *SU = getSUnit(&(*MI)))
758 dbgs() << "Missing SUnit\n";
763 //===----------------------------------------------------------------------===//
764 // LoadClusterMutation - DAG post-processing to cluster loads.
765 //===----------------------------------------------------------------------===//
768 /// \brief Post-process the DAG to create cluster edges between neighboring
770 class LoadClusterMutation : public ScheduleDAGMutation {
775 LoadInfo(SUnit *su, unsigned reg, unsigned ofs)
776 : SU(su), BaseReg(reg), Offset(ofs) {}
778 static bool LoadInfoLess(const LoadClusterMutation::LoadInfo &LHS,
779 const LoadClusterMutation::LoadInfo &RHS);
781 const TargetInstrInfo *TII;
782 const TargetRegisterInfo *TRI;
784 LoadClusterMutation(const TargetInstrInfo *tii,
785 const TargetRegisterInfo *tri)
786 : TII(tii), TRI(tri) {}
788 virtual void apply(ScheduleDAGMI *DAG);
790 void clusterNeighboringLoads(ArrayRef<SUnit*> Loads, ScheduleDAGMI *DAG);
794 bool LoadClusterMutation::LoadInfoLess(
795 const LoadClusterMutation::LoadInfo &LHS,
796 const LoadClusterMutation::LoadInfo &RHS) {
797 if (LHS.BaseReg != RHS.BaseReg)
798 return LHS.BaseReg < RHS.BaseReg;
799 return LHS.Offset < RHS.Offset;
802 void LoadClusterMutation::clusterNeighboringLoads(ArrayRef<SUnit*> Loads,
803 ScheduleDAGMI *DAG) {
804 SmallVector<LoadClusterMutation::LoadInfo,32> LoadRecords;
805 for (unsigned Idx = 0, End = Loads.size(); Idx != End; ++Idx) {
806 SUnit *SU = Loads[Idx];
809 if (TII->getLdStBaseRegImmOfs(SU->getInstr(), BaseReg, Offset, TRI))
810 LoadRecords.push_back(LoadInfo(SU, BaseReg, Offset));
812 if (LoadRecords.size() < 2)
814 std::sort(LoadRecords.begin(), LoadRecords.end(), LoadInfoLess);
815 unsigned ClusterLength = 1;
816 for (unsigned Idx = 0, End = LoadRecords.size(); Idx < (End - 1); ++Idx) {
817 if (LoadRecords[Idx].BaseReg != LoadRecords[Idx+1].BaseReg) {
822 SUnit *SUa = LoadRecords[Idx].SU;
823 SUnit *SUb = LoadRecords[Idx+1].SU;
824 if (TII->shouldClusterLoads(SUa->getInstr(), SUb->getInstr(), ClusterLength)
825 && DAG->addEdge(SUb, SDep(SUa, SDep::Cluster))) {
827 DEBUG(dbgs() << "Cluster loads SU(" << SUa->NodeNum << ") - SU("
828 << SUb->NodeNum << ")\n");
829 // Copy successor edges from SUa to SUb. Interleaving computation
830 // dependent on SUa can prevent load combining due to register reuse.
831 // Predecessor edges do not need to be copied from SUb to SUa since nearby
832 // loads should have effectively the same inputs.
833 for (SUnit::const_succ_iterator
834 SI = SUa->Succs.begin(), SE = SUa->Succs.end(); SI != SE; ++SI) {
835 if (SI->getSUnit() == SUb)
837 DEBUG(dbgs() << " Copy Succ SU(" << SI->getSUnit()->NodeNum << ")\n");
838 DAG->addEdge(SI->getSUnit(), SDep(SUb, SDep::Artificial));
847 /// \brief Callback from DAG postProcessing to create cluster edges for loads.
848 void LoadClusterMutation::apply(ScheduleDAGMI *DAG) {
849 // Map DAG NodeNum to store chain ID.
850 DenseMap<unsigned, unsigned> StoreChainIDs;
851 // Map each store chain to a set of dependent loads.
852 SmallVector<SmallVector<SUnit*,4>, 32> StoreChainDependents;
853 for (unsigned Idx = 0, End = DAG->SUnits.size(); Idx != End; ++Idx) {
854 SUnit *SU = &DAG->SUnits[Idx];
855 if (!SU->getInstr()->mayLoad())
857 unsigned ChainPredID = DAG->SUnits.size();
858 for (SUnit::const_pred_iterator
859 PI = SU->Preds.begin(), PE = SU->Preds.end(); PI != PE; ++PI) {
861 ChainPredID = PI->getSUnit()->NodeNum;
865 // Check if this chain-like pred has been seen
866 // before. ChainPredID==MaxNodeID for loads at the top of the schedule.
867 unsigned NumChains = StoreChainDependents.size();
868 std::pair<DenseMap<unsigned, unsigned>::iterator, bool> Result =
869 StoreChainIDs.insert(std::make_pair(ChainPredID, NumChains));
871 StoreChainDependents.resize(NumChains + 1);
872 StoreChainDependents[Result.first->second].push_back(SU);
874 // Iterate over the store chains.
875 for (unsigned Idx = 0, End = StoreChainDependents.size(); Idx != End; ++Idx)
876 clusterNeighboringLoads(StoreChainDependents[Idx], DAG);
879 //===----------------------------------------------------------------------===//
880 // MacroFusion - DAG post-processing to encourage fusion of macro ops.
881 //===----------------------------------------------------------------------===//
884 /// \brief Post-process the DAG to create cluster edges between instructions
885 /// that may be fused by the processor into a single operation.
886 class MacroFusion : public ScheduleDAGMutation {
887 const TargetInstrInfo *TII;
889 MacroFusion(const TargetInstrInfo *tii): TII(tii) {}
891 virtual void apply(ScheduleDAGMI *DAG);
895 /// \brief Callback from DAG postProcessing to create cluster edges to encourage
896 /// fused operations.
897 void MacroFusion::apply(ScheduleDAGMI *DAG) {
898 // For now, assume targets can only fuse with the branch.
899 MachineInstr *Branch = DAG->ExitSU.getInstr();
903 for (unsigned Idx = DAG->SUnits.size(); Idx > 0;) {
904 SUnit *SU = &DAG->SUnits[--Idx];
905 if (!TII->shouldScheduleAdjacent(SU->getInstr(), Branch))
908 // Create a single weak edge from SU to ExitSU. The only effect is to cause
909 // bottom-up scheduling to heavily prioritize the clustered SU. There is no
910 // need to copy predecessor edges from ExitSU to SU, since top-down
911 // scheduling cannot prioritize ExitSU anyway. To defer top-down scheduling
912 // of SU, we could create an artificial edge from the deepest root, but it
913 // hasn't been needed yet.
914 bool Success = DAG->addEdge(&DAG->ExitSU, SDep(SU, SDep::Cluster));
916 assert(Success && "No DAG nodes should be reachable from ExitSU");
918 DEBUG(dbgs() << "Macro Fuse SU(" << SU->NodeNum << ")\n");
923 //===----------------------------------------------------------------------===//
924 // CopyConstrain - DAG post-processing to encourage copy elimination.
925 //===----------------------------------------------------------------------===//
928 /// \brief Post-process the DAG to create weak edges from all uses of a copy to
929 /// the one use that defines the copy's source vreg, most likely an induction
930 /// variable increment.
931 class CopyConstrain : public ScheduleDAGMutation {
933 SlotIndex RegionBeginIdx;
934 // RegionEndIdx is the slot index of the last non-debug instruction in the
935 // scheduling region. So we may have RegionBeginIdx == RegionEndIdx.
936 SlotIndex RegionEndIdx;
938 CopyConstrain(const TargetInstrInfo *, const TargetRegisterInfo *) {}
940 virtual void apply(ScheduleDAGMI *DAG);
943 void constrainLocalCopy(SUnit *CopySU, ScheduleDAGMI *DAG);
947 /// constrainLocalCopy handles two possibilities:
952 /// I3: dst = src (copy)
953 /// (create pred->succ edges I0->I1, I2->I1)
956 /// I0: dst = src (copy)
960 /// (create pred->succ edges I1->I2, I3->I2)
962 /// Although the MachineScheduler is currently constrained to single blocks,
963 /// this algorithm should handle extended blocks. An EBB is a set of
964 /// contiguously numbered blocks such that the previous block in the EBB is
965 /// always the single predecessor.
966 void CopyConstrain::constrainLocalCopy(SUnit *CopySU, ScheduleDAGMI *DAG) {
967 LiveIntervals *LIS = DAG->getLIS();
968 MachineInstr *Copy = CopySU->getInstr();
970 // Check for pure vreg copies.
971 unsigned SrcReg = Copy->getOperand(1).getReg();
972 if (!TargetRegisterInfo::isVirtualRegister(SrcReg))
975 unsigned DstReg = Copy->getOperand(0).getReg();
976 if (!TargetRegisterInfo::isVirtualRegister(DstReg))
979 // Check if either the dest or source is local. If it's live across a back
980 // edge, it's not local. Note that if both vregs are live across the back
981 // edge, we cannot successfully contrain the copy without cyclic scheduling.
982 unsigned LocalReg = DstReg;
983 unsigned GlobalReg = SrcReg;
984 LiveInterval *LocalLI = &LIS->getInterval(LocalReg);
985 if (!LocalLI->isLocal(RegionBeginIdx, RegionEndIdx)) {
988 LocalLI = &LIS->getInterval(LocalReg);
989 if (!LocalLI->isLocal(RegionBeginIdx, RegionEndIdx))
992 LiveInterval *GlobalLI = &LIS->getInterval(GlobalReg);
994 // Find the global segment after the start of the local LI.
995 LiveInterval::iterator GlobalSegment = GlobalLI->find(LocalLI->beginIndex());
996 // If GlobalLI does not overlap LocalLI->start, then a copy directly feeds a
997 // local live range. We could create edges from other global uses to the local
998 // start, but the coalescer should have already eliminated these cases, so
999 // don't bother dealing with it.
1000 if (GlobalSegment == GlobalLI->end())
1003 // If GlobalSegment is killed at the LocalLI->start, the call to find()
1004 // returned the next global segment. But if GlobalSegment overlaps with
1005 // LocalLI->start, then advance to the next segement. If a hole in GlobalLI
1006 // exists in LocalLI's vicinity, GlobalSegment will be the end of the hole.
1007 if (GlobalSegment->contains(LocalLI->beginIndex()))
1010 if (GlobalSegment == GlobalLI->end())
1013 // Check if GlobalLI contains a hole in the vicinity of LocalLI.
1014 if (GlobalSegment != GlobalLI->begin()) {
1015 // Two address defs have no hole.
1016 if (SlotIndex::isSameInstr(llvm::prior(GlobalSegment)->end,
1017 GlobalSegment->start)) {
1020 // If the prior global segment may be defined by the same two-address
1021 // instruction that also defines LocalLI, then can't make a hole here.
1022 if (SlotIndex::isSameInstr(llvm::prior(GlobalSegment)->start,
1023 LocalLI->beginIndex())) {
1026 // If GlobalLI has a prior segment, it must be live into the EBB. Otherwise
1027 // it would be a disconnected component in the live range.
1028 assert(llvm::prior(GlobalSegment)->start < LocalLI->beginIndex() &&
1029 "Disconnected LRG within the scheduling region.");
1031 MachineInstr *GlobalDef = LIS->getInstructionFromIndex(GlobalSegment->start);
1035 SUnit *GlobalSU = DAG->getSUnit(GlobalDef);
1039 // GlobalDef is the bottom of the GlobalLI hole. Open the hole by
1040 // constraining the uses of the last local def to precede GlobalDef.
1041 SmallVector<SUnit*,8> LocalUses;
1042 const VNInfo *LastLocalVN = LocalLI->getVNInfoBefore(LocalLI->endIndex());
1043 MachineInstr *LastLocalDef = LIS->getInstructionFromIndex(LastLocalVN->def);
1044 SUnit *LastLocalSU = DAG->getSUnit(LastLocalDef);
1045 for (SUnit::const_succ_iterator
1046 I = LastLocalSU->Succs.begin(), E = LastLocalSU->Succs.end();
1048 if (I->getKind() != SDep::Data || I->getReg() != LocalReg)
1050 if (I->getSUnit() == GlobalSU)
1052 if (!DAG->canAddEdge(GlobalSU, I->getSUnit()))
1054 LocalUses.push_back(I->getSUnit());
1056 // Open the top of the GlobalLI hole by constraining any earlier global uses
1057 // to precede the start of LocalLI.
1058 SmallVector<SUnit*,8> GlobalUses;
1059 MachineInstr *FirstLocalDef =
1060 LIS->getInstructionFromIndex(LocalLI->beginIndex());
1061 SUnit *FirstLocalSU = DAG->getSUnit(FirstLocalDef);
1062 for (SUnit::const_pred_iterator
1063 I = GlobalSU->Preds.begin(), E = GlobalSU->Preds.end(); I != E; ++I) {
1064 if (I->getKind() != SDep::Anti || I->getReg() != GlobalReg)
1066 if (I->getSUnit() == FirstLocalSU)
1068 if (!DAG->canAddEdge(FirstLocalSU, I->getSUnit()))
1070 GlobalUses.push_back(I->getSUnit());
1072 DEBUG(dbgs() << "Constraining copy SU(" << CopySU->NodeNum << ")\n");
1073 // Add the weak edges.
1074 for (SmallVectorImpl<SUnit*>::const_iterator
1075 I = LocalUses.begin(), E = LocalUses.end(); I != E; ++I) {
1076 DEBUG(dbgs() << " Local use SU(" << (*I)->NodeNum << ") -> SU("
1077 << GlobalSU->NodeNum << ")\n");
1078 DAG->addEdge(GlobalSU, SDep(*I, SDep::Weak));
1080 for (SmallVectorImpl<SUnit*>::const_iterator
1081 I = GlobalUses.begin(), E = GlobalUses.end(); I != E; ++I) {
1082 DEBUG(dbgs() << " Global use SU(" << (*I)->NodeNum << ") -> SU("
1083 << FirstLocalSU->NodeNum << ")\n");
1084 DAG->addEdge(FirstLocalSU, SDep(*I, SDep::Weak));
1088 /// \brief Callback from DAG postProcessing to create weak edges to encourage
1089 /// copy elimination.
1090 void CopyConstrain::apply(ScheduleDAGMI *DAG) {
1091 MachineBasicBlock::iterator FirstPos = nextIfDebug(DAG->begin(), DAG->end());
1092 if (FirstPos == DAG->end())
1094 RegionBeginIdx = DAG->getLIS()->getInstructionIndex(&*FirstPos);
1095 RegionEndIdx = DAG->getLIS()->getInstructionIndex(
1096 &*priorNonDebug(DAG->end(), DAG->begin()));
1098 for (unsigned Idx = 0, End = DAG->SUnits.size(); Idx != End; ++Idx) {
1099 SUnit *SU = &DAG->SUnits[Idx];
1100 if (!SU->getInstr()->isCopy())
1103 constrainLocalCopy(SU, DAG);
1107 //===----------------------------------------------------------------------===//
1108 // ConvergingScheduler - Implementation of the generic MachineSchedStrategy.
1109 //===----------------------------------------------------------------------===//
1112 /// ConvergingScheduler shrinks the unscheduled zone using heuristics to balance
1114 class ConvergingScheduler : public MachineSchedStrategy {
1116 /// Represent the type of SchedCandidate found within a single queue.
1117 /// pickNodeBidirectional depends on these listed by decreasing priority.
1119 NoCand, PhysRegCopy, RegExcess, RegCritical, Cluster, Weak, RegMax,
1120 ResourceReduce, ResourceDemand, BotHeightReduce, BotPathReduce,
1121 TopDepthReduce, TopPathReduce, NextDefUse, NodeOrder};
1124 static const char *getReasonStr(ConvergingScheduler::CandReason Reason);
1127 /// Policy for scheduling the next instruction in the candidate's zone.
1130 unsigned ReduceResIdx;
1131 unsigned DemandResIdx;
1133 CandPolicy(): ReduceLatency(false), ReduceResIdx(0), DemandResIdx(0) {}
1136 /// Status of an instruction's critical resource consumption.
1137 struct SchedResourceDelta {
1138 // Count critical resources in the scheduled region required by SU.
1139 unsigned CritResources;
1141 // Count critical resources from another region consumed by SU.
1142 unsigned DemandedResources;
1144 SchedResourceDelta(): CritResources(0), DemandedResources(0) {}
1146 bool operator==(const SchedResourceDelta &RHS) const {
1147 return CritResources == RHS.CritResources
1148 && DemandedResources == RHS.DemandedResources;
1150 bool operator!=(const SchedResourceDelta &RHS) const {
1151 return !operator==(RHS);
1155 /// Store the state used by ConvergingScheduler heuristics, required for the
1156 /// lifetime of one invocation of pickNode().
1157 struct SchedCandidate {
1160 // The best SUnit candidate.
1163 // The reason for this candidate.
1166 // Set of reasons that apply to multiple candidates.
1167 uint32_t RepeatReasonSet;
1169 // Register pressure values for the best candidate.
1170 RegPressureDelta RPDelta;
1172 // Critical resource consumption of the best candidate.
1173 SchedResourceDelta ResDelta;
1175 SchedCandidate(const CandPolicy &policy)
1176 : Policy(policy), SU(NULL), Reason(NoCand), RepeatReasonSet(0) {}
1178 bool isValid() const { return SU; }
1180 // Copy the status of another candidate without changing policy.
1181 void setBest(SchedCandidate &Best) {
1182 assert(Best.Reason != NoCand && "uninitialized Sched candidate");
1184 Reason = Best.Reason;
1185 RPDelta = Best.RPDelta;
1186 ResDelta = Best.ResDelta;
1189 bool isRepeat(CandReason R) { return RepeatReasonSet & (1 << R); }
1190 void setRepeat(CandReason R) { RepeatReasonSet |= (1 << R); }
1192 void initResourceDelta(const ScheduleDAGMI *DAG,
1193 const TargetSchedModel *SchedModel);
1196 /// Summarize the unscheduled region.
1197 struct SchedRemainder {
1198 // Critical path through the DAG in expected latency.
1199 unsigned CriticalPath;
1201 // Scaled count of micro-ops left to schedule.
1202 unsigned RemIssueCount;
1204 // Unscheduled resources
1205 SmallVector<unsigned, 16> RemainingCounts;
1210 RemainingCounts.clear();
1213 SchedRemainder() { reset(); }
1215 void init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel);
1218 /// Each Scheduling boundary is associated with ready queues. It tracks the
1219 /// current cycle in the direction of movement, and maintains the state
1220 /// of "hazards" and other interlocks at the current cycle.
1221 struct SchedBoundary {
1223 const TargetSchedModel *SchedModel;
1224 SchedRemainder *Rem;
1226 ReadyQueue Available;
1230 // For heuristics, keep a list of the nodes that immediately depend on the
1231 // most recently scheduled node.
1232 SmallPtrSet<const SUnit*, 8> NextSUs;
1234 ScheduleHazardRecognizer *HazardRec;
1236 /// Number of cycles it takes to issue the instructions scheduled in this
1237 /// zone. It is defined as: scheduled-micro-ops / issue-width + stalls.
1238 /// See getStalls().
1241 /// Micro-ops issued in the current cycle
1244 /// MinReadyCycle - Cycle of the soonest available instruction.
1245 unsigned MinReadyCycle;
1247 // The expected latency of the critical path in this scheduled zone.
1248 unsigned ExpectedLatency;
1250 // The latency of dependence chains leading into this zone.
1251 // For each node scheduled top-down: DLat = max DLat, N.Depth.
1252 // For each cycle scheduled: DLat -= 1.
1253 unsigned DependentLatency;
1255 /// Count the scheduled (issued) micro-ops that can be retired by
1256 /// time=CurrCycle assuming the first scheduled instr is retired at time=0.
1257 unsigned RetiredMOps;
1259 // Count scheduled resources that have been executed. Resources are
1260 // considered executed if they become ready in the time that it takes to
1261 // saturate any resource including the one in question. Counts are scaled
1262 // for direct comparison with other resources. Counts can be compared with
1263 // MOps * getMicroOpFactor and Latency * getLatencyFactor.
1264 SmallVector<unsigned, 16> ExecutedResCounts;
1266 /// Cache the max count for a single resource.
1267 unsigned MaxExecutedResCount;
1269 // Cache the critical resources ID in this scheduled zone.
1270 unsigned ZoneCritResIdx;
1272 // Is the scheduled region resource limited vs. latency limited.
1273 bool IsResourceLimited;
1276 // Remember the greatest operand latency as an upper bound on the number of
1277 // times we should retry the pending queue because of a hazard.
1278 unsigned MaxObservedLatency;
1282 // A new HazardRec is created for each DAG and owned by SchedBoundary.
1287 CheckPending = false;
1292 MinReadyCycle = UINT_MAX;
1293 ExpectedLatency = 0;
1294 DependentLatency = 0;
1296 MaxExecutedResCount = 0;
1298 IsResourceLimited = false;
1300 MaxObservedLatency = 0;
1302 // Reserve a zero-count for invalid CritResIdx.
1303 ExecutedResCounts.resize(1);
1304 assert(!ExecutedResCounts[0] && "nonzero count for bad resource");
1307 /// Pending queues extend the ready queues with the same ID and the
1308 /// PendingFlag set.
1309 SchedBoundary(unsigned ID, const Twine &Name):
1310 DAG(0), SchedModel(0), Rem(0), Available(ID, Name+".A"),
1311 Pending(ID << ConvergingScheduler::LogMaxQID, Name+".P"),
1316 ~SchedBoundary() { delete HazardRec; }
1318 void init(ScheduleDAGMI *dag, const TargetSchedModel *smodel,
1319 SchedRemainder *rem);
1321 bool isTop() const {
1322 return Available.getID() == ConvergingScheduler::TopQID;
1326 const char *getResourceName(unsigned PIdx) {
1329 return SchedModel->getProcResource(PIdx)->Name;
1333 /// Get the number of latency cycles "covered" by the scheduled
1334 /// instructions. This is the larger of the critical path within the zone
1335 /// and the number of cycles required to issue the instructions.
1336 unsigned getScheduledLatency() const {
1337 return std::max(ExpectedLatency, CurrCycle);
1340 unsigned getUnscheduledLatency(SUnit *SU) const {
1341 return isTop() ? SU->getHeight() : SU->getDepth();
1344 unsigned getResourceCount(unsigned ResIdx) const {
1345 return ExecutedResCounts[ResIdx];
1348 /// Get the scaled count of scheduled micro-ops and resources, including
1349 /// executed resources.
1350 unsigned getCriticalCount() const {
1351 if (!ZoneCritResIdx)
1352 return RetiredMOps * SchedModel->getMicroOpFactor();
1353 return getResourceCount(ZoneCritResIdx);
1356 /// Get a scaled count for the minimum execution time of the scheduled
1357 /// micro-ops that are ready to execute by getExecutedCount. Notice the
1359 unsigned getExecutedCount() const {
1360 return std::max(CurrCycle * SchedModel->getLatencyFactor(),
1361 MaxExecutedResCount);
1364 bool checkHazard(SUnit *SU);
1366 unsigned findMaxLatency(ArrayRef<SUnit*> ReadySUs);
1368 unsigned getOtherResourceCount(unsigned &OtherCritIdx);
1370 void setPolicy(CandPolicy &Policy, SchedBoundary &OtherZone);
1372 void releaseNode(SUnit *SU, unsigned ReadyCycle);
1374 void bumpCycle(unsigned NextCycle);
1376 void incExecutedResources(unsigned PIdx, unsigned Count);
1378 unsigned countResource(unsigned PIdx, unsigned Cycles, unsigned ReadyCycle);
1380 void bumpNode(SUnit *SU);
1382 void releasePending();
1384 void removeReady(SUnit *SU);
1386 SUnit *pickOnlyChoice();
1389 void dumpScheduledState();
1395 const TargetSchedModel *SchedModel;
1396 const TargetRegisterInfo *TRI;
1398 // State of the top and bottom scheduled instruction boundaries.
1404 /// SUnit::NodeQueueId: 0 (none), 1 (top), 2 (bot), 3 (both)
1411 ConvergingScheduler():
1412 DAG(0), SchedModel(0), TRI(0), Top(TopQID, "TopQ"), Bot(BotQID, "BotQ") {}
1414 virtual void initialize(ScheduleDAGMI *dag);
1416 virtual SUnit *pickNode(bool &IsTopNode);
1418 virtual void schedNode(SUnit *SU, bool IsTopNode);
1420 virtual void releaseTopNode(SUnit *SU);
1422 virtual void releaseBottomNode(SUnit *SU);
1424 virtual void registerRoots();
1427 void tryCandidate(SchedCandidate &Cand,
1428 SchedCandidate &TryCand,
1429 SchedBoundary &Zone,
1430 const RegPressureTracker &RPTracker,
1431 RegPressureTracker &TempTracker);
1433 SUnit *pickNodeBidirectional(bool &IsTopNode);
1435 void pickNodeFromQueue(SchedBoundary &Zone,
1436 const RegPressureTracker &RPTracker,
1437 SchedCandidate &Candidate);
1439 void reschedulePhysRegCopies(SUnit *SU, bool isTop);
1442 void traceCandidate(const SchedCandidate &Cand);
1447 void ConvergingScheduler::SchedRemainder::
1448 init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel) {
1450 if (!SchedModel->hasInstrSchedModel())
1452 RemainingCounts.resize(SchedModel->getNumProcResourceKinds());
1453 for (std::vector<SUnit>::iterator
1454 I = DAG->SUnits.begin(), E = DAG->SUnits.end(); I != E; ++I) {
1455 const MCSchedClassDesc *SC = DAG->getSchedClass(&*I);
1456 RemIssueCount += SchedModel->getNumMicroOps(I->getInstr(), SC)
1457 * SchedModel->getMicroOpFactor();
1458 for (TargetSchedModel::ProcResIter
1459 PI = SchedModel->getWriteProcResBegin(SC),
1460 PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) {
1461 unsigned PIdx = PI->ProcResourceIdx;
1462 unsigned Factor = SchedModel->getResourceFactor(PIdx);
1463 RemainingCounts[PIdx] += (Factor * PI->Cycles);
1468 void ConvergingScheduler::SchedBoundary::
1469 init(ScheduleDAGMI *dag, const TargetSchedModel *smodel, SchedRemainder *rem) {
1472 SchedModel = smodel;
1474 if (SchedModel->hasInstrSchedModel())
1475 ExecutedResCounts.resize(SchedModel->getNumProcResourceKinds());
1478 void ConvergingScheduler::initialize(ScheduleDAGMI *dag) {
1480 SchedModel = DAG->getSchedModel();
1483 Rem.init(DAG, SchedModel);
1484 Top.init(DAG, SchedModel, &Rem);
1485 Bot.init(DAG, SchedModel, &Rem);
1487 // Initialize resource counts.
1489 // Initialize the HazardRecognizers. If itineraries don't exist, are empty, or
1490 // are disabled, then these HazardRecs will be disabled.
1491 const InstrItineraryData *Itin = SchedModel->getInstrItineraries();
1492 const TargetMachine &TM = DAG->MF.getTarget();
1493 Top.HazardRec = TM.getInstrInfo()->CreateTargetMIHazardRecognizer(Itin, DAG);
1494 Bot.HazardRec = TM.getInstrInfo()->CreateTargetMIHazardRecognizer(Itin, DAG);
1496 assert((!ForceTopDown || !ForceBottomUp) &&
1497 "-misched-topdown incompatible with -misched-bottomup");
1500 void ConvergingScheduler::releaseTopNode(SUnit *SU) {
1501 if (SU->isScheduled)
1504 for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
1508 unsigned PredReadyCycle = I->getSUnit()->TopReadyCycle;
1509 unsigned Latency = I->getLatency();
1511 Top.MaxObservedLatency = std::max(Latency, Top.MaxObservedLatency);
1513 if (SU->TopReadyCycle < PredReadyCycle + Latency)
1514 SU->TopReadyCycle = PredReadyCycle + Latency;
1516 Top.releaseNode(SU, SU->TopReadyCycle);
1519 void ConvergingScheduler::releaseBottomNode(SUnit *SU) {
1520 if (SU->isScheduled)
1523 assert(SU->getInstr() && "Scheduled SUnit must have instr");
1525 for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
1529 unsigned SuccReadyCycle = I->getSUnit()->BotReadyCycle;
1530 unsigned Latency = I->getLatency();
1532 Bot.MaxObservedLatency = std::max(Latency, Bot.MaxObservedLatency);
1534 if (SU->BotReadyCycle < SuccReadyCycle + Latency)
1535 SU->BotReadyCycle = SuccReadyCycle + Latency;
1537 Bot.releaseNode(SU, SU->BotReadyCycle);
1540 void ConvergingScheduler::registerRoots() {
1541 Rem.CriticalPath = DAG->ExitSU.getDepth();
1542 // Some roots may not feed into ExitSU. Check all of them in case.
1543 for (std::vector<SUnit*>::const_iterator
1544 I = Bot.Available.begin(), E = Bot.Available.end(); I != E; ++I) {
1545 if ((*I)->getDepth() > Rem.CriticalPath)
1546 Rem.CriticalPath = (*I)->getDepth();
1548 DEBUG(dbgs() << "Critical Path: " << Rem.CriticalPath << '\n');
1551 /// Does this SU have a hazard within the current instruction group.
1553 /// The scheduler supports two modes of hazard recognition. The first is the
1554 /// ScheduleHazardRecognizer API. It is a fully general hazard recognizer that
1555 /// supports highly complicated in-order reservation tables
1556 /// (ScoreboardHazardRecognizer) and arbitraty target-specific logic.
1558 /// The second is a streamlined mechanism that checks for hazards based on
1559 /// simple counters that the scheduler itself maintains. It explicitly checks
1560 /// for instruction dispatch limitations, including the number of micro-ops that
1561 /// can dispatch per cycle.
1563 /// TODO: Also check whether the SU must start a new group.
1564 bool ConvergingScheduler::SchedBoundary::checkHazard(SUnit *SU) {
1565 if (HazardRec->isEnabled())
1566 return HazardRec->getHazardType(SU) != ScheduleHazardRecognizer::NoHazard;
1568 unsigned uops = SchedModel->getNumMicroOps(SU->getInstr());
1569 if ((CurrMOps > 0) && (CurrMOps + uops > SchedModel->getIssueWidth())) {
1570 DEBUG(dbgs() << " SU(" << SU->NodeNum << ") uops="
1571 << SchedModel->getNumMicroOps(SU->getInstr()) << '\n');
1577 // Find the unscheduled node in ReadySUs with the highest latency.
1578 unsigned ConvergingScheduler::SchedBoundary::
1579 findMaxLatency(ArrayRef<SUnit*> ReadySUs) {
1581 unsigned RemLatency = 0;
1582 for (ArrayRef<SUnit*>::iterator I = ReadySUs.begin(), E = ReadySUs.end();
1584 unsigned L = getUnscheduledLatency(*I);
1585 if (L > RemLatency) {
1591 DEBUG(dbgs() << Available.getName() << " RemLatency SU("
1592 << LateSU->NodeNum << ") " << RemLatency << "c\n");
1597 // Count resources in this zone and the remaining unscheduled
1598 // instruction. Return the max count, scaled. Set OtherCritIdx to the critical
1599 // resource index, or zero if the zone is issue limited.
1600 unsigned ConvergingScheduler::SchedBoundary::
1601 getOtherResourceCount(unsigned &OtherCritIdx) {
1603 if (!SchedModel->hasInstrSchedModel())
1606 unsigned OtherCritCount = Rem->RemIssueCount
1607 + (RetiredMOps * SchedModel->getMicroOpFactor());
1608 DEBUG(dbgs() << " " << Available.getName() << " + Remain MOps: "
1609 << OtherCritCount / SchedModel->getMicroOpFactor() << '\n');
1610 for (unsigned PIdx = 1, PEnd = SchedModel->getNumProcResourceKinds();
1611 PIdx != PEnd; ++PIdx) {
1612 unsigned OtherCount = getResourceCount(PIdx) + Rem->RemainingCounts[PIdx];
1613 if (OtherCount > OtherCritCount) {
1614 OtherCritCount = OtherCount;
1615 OtherCritIdx = PIdx;
1619 DEBUG(dbgs() << " " << Available.getName() << " + Remain CritRes: "
1620 << OtherCritCount / SchedModel->getResourceFactor(OtherCritIdx)
1621 << " " << getResourceName(OtherCritIdx) << "\n");
1623 return OtherCritCount;
1626 /// Set the CandPolicy for this zone given the current resources and latencies
1627 /// inside and outside the zone.
1628 void ConvergingScheduler::SchedBoundary::setPolicy(CandPolicy &Policy,
1629 SchedBoundary &OtherZone) {
1630 // Now that potential stalls have been considered, apply preemptive heuristics
1631 // based on the the total latency and resources inside and outside this
1634 // Compute remaining latency. We need this both to determine whether the
1635 // overall schedule has become latency-limited and whether the instructions
1636 // outside this zone are resource or latency limited.
1638 // The "dependent" latency is updated incrementally during scheduling as the
1639 // max height/depth of scheduled nodes minus the cycles since it was
1641 // DLat = max (N.depth - (CurrCycle - N.ReadyCycle) for N in Zone
1643 // The "independent" latency is the max ready queue depth:
1644 // ILat = max N.depth for N in Available|Pending
1646 // RemainingLatency is the greater of independent and dependent latency.
1647 unsigned RemLatency = DependentLatency;
1648 RemLatency = std::max(RemLatency, findMaxLatency(Available.elements()));
1649 RemLatency = std::max(RemLatency, findMaxLatency(Pending.elements()));
1651 // Compute the critical resource outside the zone.
1652 unsigned OtherCritIdx;
1653 unsigned OtherCount = OtherZone.getOtherResourceCount(OtherCritIdx);
1655 bool OtherResLimited = false;
1656 if (SchedModel->hasInstrSchedModel()) {
1657 unsigned LFactor = SchedModel->getLatencyFactor();
1658 OtherResLimited = (int)(OtherCount - (RemLatency * LFactor)) > (int)LFactor;
1660 if (!OtherResLimited && (RemLatency + CurrCycle > Rem->CriticalPath)) {
1661 Policy.ReduceLatency |= true;
1662 DEBUG(dbgs() << " " << Available.getName() << " RemainingLatency "
1663 << RemLatency << " + " << CurrCycle << "c > CritPath "
1664 << Rem->CriticalPath << "\n");
1666 // If the same resource is limiting inside and outside the zone, do nothing.
1667 if (ZoneCritResIdx == OtherCritIdx)
1671 if (IsResourceLimited) {
1672 dbgs() << " " << Available.getName() << " ResourceLimited: "
1673 << getResourceName(ZoneCritResIdx) << "\n";
1675 if (OtherResLimited)
1676 dbgs() << " RemainingLimit: " << getResourceName(OtherCritIdx) << "\n";
1677 if (!IsResourceLimited && !OtherResLimited)
1678 dbgs() << " Latency limited both directions.\n");
1680 if (IsResourceLimited && !Policy.ReduceResIdx)
1681 Policy.ReduceResIdx = ZoneCritResIdx;
1683 if (OtherResLimited)
1684 Policy.DemandResIdx = OtherCritIdx;
1687 void ConvergingScheduler::SchedBoundary::releaseNode(SUnit *SU,
1688 unsigned ReadyCycle) {
1689 if (ReadyCycle < MinReadyCycle)
1690 MinReadyCycle = ReadyCycle;
1692 // Check for interlocks first. For the purpose of other heuristics, an
1693 // instruction that cannot issue appears as if it's not in the ReadyQueue.
1694 bool IsBuffered = SchedModel->getMicroOpBufferSize() != 0;
1695 if ((!IsBuffered && ReadyCycle > CurrCycle) || checkHazard(SU))
1700 // Record this node as an immediate dependent of the scheduled node.
1704 /// Move the boundary of scheduled code by one cycle.
1705 void ConvergingScheduler::SchedBoundary::bumpCycle(unsigned NextCycle) {
1706 if (SchedModel->getMicroOpBufferSize() == 0) {
1707 assert(MinReadyCycle < UINT_MAX && "MinReadyCycle uninitialized");
1708 if (MinReadyCycle > NextCycle)
1709 NextCycle = MinReadyCycle;
1711 // Update the current micro-ops, which will issue in the next cycle.
1712 unsigned DecMOps = SchedModel->getIssueWidth() * (NextCycle - CurrCycle);
1713 CurrMOps = (CurrMOps <= DecMOps) ? 0 : CurrMOps - DecMOps;
1715 // Decrement DependentLatency based on the next cycle.
1716 if ((NextCycle - CurrCycle) > DependentLatency)
1717 DependentLatency = 0;
1719 DependentLatency -= (NextCycle - CurrCycle);
1721 if (!HazardRec->isEnabled()) {
1722 // Bypass HazardRec virtual calls.
1723 CurrCycle = NextCycle;
1726 // Bypass getHazardType calls in case of long latency.
1727 for (; CurrCycle != NextCycle; ++CurrCycle) {
1729 HazardRec->AdvanceCycle();
1731 HazardRec->RecedeCycle();
1734 CheckPending = true;
1735 unsigned LFactor = SchedModel->getLatencyFactor();
1737 (int)(getCriticalCount() - (getScheduledLatency() * LFactor))
1740 DEBUG(dbgs() << "Cycle: " << CurrCycle << ' ' << Available.getName() << '\n');
1743 void ConvergingScheduler::SchedBoundary::incExecutedResources(unsigned PIdx,
1745 ExecutedResCounts[PIdx] += Count;
1746 if (ExecutedResCounts[PIdx] > MaxExecutedResCount)
1747 MaxExecutedResCount = ExecutedResCounts[PIdx];
1750 /// Add the given processor resource to this scheduled zone.
1752 /// \param Cycles indicates the number of consecutive (non-pipelined) cycles
1753 /// during which this resource is consumed.
1755 /// \return the next cycle at which the instruction may execute without
1756 /// oversubscribing resources.
1757 unsigned ConvergingScheduler::SchedBoundary::
1758 countResource(unsigned PIdx, unsigned Cycles, unsigned ReadyCycle) {
1759 unsigned Factor = SchedModel->getResourceFactor(PIdx);
1760 unsigned Count = Factor * Cycles;
1761 DEBUG(dbgs() << " " << getResourceName(PIdx)
1762 << " +" << Cycles << "x" << Factor << "u\n");
1764 // Update Executed resources counts.
1765 incExecutedResources(PIdx, Count);
1766 assert(Rem->RemainingCounts[PIdx] >= Count && "resource double counted");
1767 Rem->RemainingCounts[PIdx] -= Count;
1769 // Check if this resource exceeds the current critical resource. If so, it
1770 // becomes the critical resource.
1771 if (ZoneCritResIdx != PIdx && (getResourceCount(PIdx) > getCriticalCount())) {
1772 ZoneCritResIdx = PIdx;
1773 DEBUG(dbgs() << " *** Critical resource "
1774 << getResourceName(PIdx) << ": "
1775 << getResourceCount(PIdx) / SchedModel->getLatencyFactor() << "c\n");
1777 // TODO: We don't yet model reserved resources. It's not hard though.
1781 /// Move the boundary of scheduled code by one SUnit.
1782 void ConvergingScheduler::SchedBoundary::bumpNode(SUnit *SU) {
1783 // Update the reservation table.
1784 if (HazardRec->isEnabled()) {
1785 if (!isTop() && SU->isCall) {
1786 // Calls are scheduled with their preceding instructions. For bottom-up
1787 // scheduling, clear the pipeline state before emitting.
1790 HazardRec->EmitInstruction(SU);
1792 const MCSchedClassDesc *SC = DAG->getSchedClass(SU);
1793 unsigned IncMOps = SchedModel->getNumMicroOps(SU->getInstr());
1794 CurrMOps += IncMOps;
1795 // checkHazard prevents scheduling multiple instructions per cycle that exceed
1796 // issue width. However, we commonly reach the maximum. In this case
1797 // opportunistically bump the cycle to avoid uselessly checking everything in
1798 // the readyQ. Furthermore, a single instruction may produce more than one
1799 // cycle's worth of micro-ops.
1801 // TODO: Also check if this SU must end a dispatch group.
1802 unsigned NextCycle = CurrCycle;
1803 if (CurrMOps >= SchedModel->getIssueWidth()) {
1805 DEBUG(dbgs() << " *** Max MOps " << CurrMOps
1806 << " at cycle " << CurrCycle << '\n');
1808 unsigned ReadyCycle = (isTop() ? SU->TopReadyCycle : SU->BotReadyCycle);
1809 DEBUG(dbgs() << " Ready @" << ReadyCycle << "c\n");
1811 switch (SchedModel->getMicroOpBufferSize()) {
1813 assert(ReadyCycle <= CurrCycle && "Broken PendingQueue");
1816 if (ReadyCycle > NextCycle) {
1817 NextCycle = ReadyCycle;
1818 DEBUG(dbgs() << " *** Stall until: " << ReadyCycle << "\n");
1822 // We don't currently model the OOO reorder buffer, so consider all
1823 // scheduled MOps to be "retired".
1826 RetiredMOps += IncMOps;
1828 // Update resource counts and critical resource.
1829 if (SchedModel->hasInstrSchedModel()) {
1830 unsigned DecRemIssue = IncMOps * SchedModel->getMicroOpFactor();
1831 assert(Rem->RemIssueCount >= DecRemIssue && "MOps double counted");
1832 Rem->RemIssueCount -= DecRemIssue;
1833 if (ZoneCritResIdx) {
1834 // Scale scheduled micro-ops for comparing with the critical resource.
1835 unsigned ScaledMOps =
1836 RetiredMOps * SchedModel->getMicroOpFactor();
1838 // If scaled micro-ops are now more than the previous critical resource by
1839 // a full cycle, then micro-ops issue becomes critical.
1840 if ((int)(ScaledMOps - getResourceCount(ZoneCritResIdx))
1841 >= (int)SchedModel->getLatencyFactor()) {
1843 DEBUG(dbgs() << " *** Critical resource NumMicroOps: "
1844 << ScaledMOps / SchedModel->getLatencyFactor() << "c\n");
1847 for (TargetSchedModel::ProcResIter
1848 PI = SchedModel->getWriteProcResBegin(SC),
1849 PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) {
1851 countResource(PI->ProcResourceIdx, PI->Cycles, ReadyCycle);
1852 if (RCycle > NextCycle)
1856 // Update ExpectedLatency and DependentLatency.
1857 unsigned &TopLatency = isTop() ? ExpectedLatency : DependentLatency;
1858 unsigned &BotLatency = isTop() ? DependentLatency : ExpectedLatency;
1859 if (SU->getDepth() > TopLatency) {
1860 TopLatency = SU->getDepth();
1861 DEBUG(dbgs() << " " << Available.getName()
1862 << " TopLatency SU(" << SU->NodeNum << ") " << TopLatency << "c\n");
1864 if (SU->getHeight() > BotLatency) {
1865 BotLatency = SU->getHeight();
1866 DEBUG(dbgs() << " " << Available.getName()
1867 << " BotLatency SU(" << SU->NodeNum << ") " << BotLatency << "c\n");
1869 // If we stall for any reason, bump the cycle.
1870 if (NextCycle > CurrCycle) {
1871 bumpCycle(NextCycle);
1874 // After updating ZoneCritResIdx and ExpectedLatency, check if we're
1875 // resource limited. If a stall occured, bumpCycle does this.
1876 unsigned LFactor = SchedModel->getLatencyFactor();
1878 (int)(getCriticalCount() - (getScheduledLatency() * LFactor))
1881 DEBUG(dumpScheduledState());
1884 /// Release pending ready nodes in to the available queue. This makes them
1885 /// visible to heuristics.
1886 void ConvergingScheduler::SchedBoundary::releasePending() {
1887 // If the available queue is empty, it is safe to reset MinReadyCycle.
1888 if (Available.empty())
1889 MinReadyCycle = UINT_MAX;
1891 // Check to see if any of the pending instructions are ready to issue. If
1892 // so, add them to the available queue.
1893 bool IsBuffered = SchedModel->getMicroOpBufferSize() != 0;
1894 for (unsigned i = 0, e = Pending.size(); i != e; ++i) {
1895 SUnit *SU = *(Pending.begin()+i);
1896 unsigned ReadyCycle = isTop() ? SU->TopReadyCycle : SU->BotReadyCycle;
1898 if (ReadyCycle < MinReadyCycle)
1899 MinReadyCycle = ReadyCycle;
1901 if (!IsBuffered && ReadyCycle > CurrCycle)
1904 if (checkHazard(SU))
1908 Pending.remove(Pending.begin()+i);
1911 DEBUG(if (!Pending.empty()) Pending.dump());
1912 CheckPending = false;
1915 /// Remove SU from the ready set for this boundary.
1916 void ConvergingScheduler::SchedBoundary::removeReady(SUnit *SU) {
1917 if (Available.isInQueue(SU))
1918 Available.remove(Available.find(SU));
1920 assert(Pending.isInQueue(SU) && "bad ready count");
1921 Pending.remove(Pending.find(SU));
1925 /// If this queue only has one ready candidate, return it. As a side effect,
1926 /// defer any nodes that now hit a hazard, and advance the cycle until at least
1927 /// one node is ready. If multiple instructions are ready, return NULL.
1928 SUnit *ConvergingScheduler::SchedBoundary::pickOnlyChoice() {
1933 // Defer any ready instrs that now have a hazard.
1934 for (ReadyQueue::iterator I = Available.begin(); I != Available.end();) {
1935 if (checkHazard(*I)) {
1937 I = Available.remove(I);
1943 for (unsigned i = 0; Available.empty(); ++i) {
1944 assert(i <= (HazardRec->getMaxLookAhead() + MaxObservedLatency) &&
1945 "permanent hazard"); (void)i;
1946 bumpCycle(CurrCycle + 1);
1949 if (Available.size() == 1)
1950 return *Available.begin();
1955 // This is useful information to dump after bumpNode.
1956 // Note that the Queue contents are more useful before pickNodeFromQueue.
1957 void ConvergingScheduler::SchedBoundary::dumpScheduledState() {
1960 if (ZoneCritResIdx) {
1961 ResFactor = SchedModel->getResourceFactor(ZoneCritResIdx);
1962 ResCount = getResourceCount(ZoneCritResIdx);
1965 ResFactor = SchedModel->getMicroOpFactor();
1966 ResCount = RetiredMOps * SchedModel->getMicroOpFactor();
1968 unsigned LFactor = SchedModel->getLatencyFactor();
1969 dbgs() << Available.getName() << " @" << CurrCycle << "c\n"
1970 << " Retired: " << RetiredMOps;
1971 dbgs() << "\n Executed: " << getExecutedCount() / LFactor << "c";
1972 dbgs() << "\n Critical: " << ResCount / LFactor << "c, "
1973 << ResCount / ResFactor << " " << getResourceName(ZoneCritResIdx)
1974 << "\n ExpectedLatency: " << ExpectedLatency << "c\n"
1975 << (IsResourceLimited ? " - Resource" : " - Latency")
1980 void ConvergingScheduler::SchedCandidate::
1981 initResourceDelta(const ScheduleDAGMI *DAG,
1982 const TargetSchedModel *SchedModel) {
1983 if (!Policy.ReduceResIdx && !Policy.DemandResIdx)
1986 const MCSchedClassDesc *SC = DAG->getSchedClass(SU);
1987 for (TargetSchedModel::ProcResIter
1988 PI = SchedModel->getWriteProcResBegin(SC),
1989 PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) {
1990 if (PI->ProcResourceIdx == Policy.ReduceResIdx)
1991 ResDelta.CritResources += PI->Cycles;
1992 if (PI->ProcResourceIdx == Policy.DemandResIdx)
1993 ResDelta.DemandedResources += PI->Cycles;
1998 /// Return true if this heuristic determines order.
1999 static bool tryLess(int TryVal, int CandVal,
2000 ConvergingScheduler::SchedCandidate &TryCand,
2001 ConvergingScheduler::SchedCandidate &Cand,
2002 ConvergingScheduler::CandReason Reason) {
2003 if (TryVal < CandVal) {
2004 TryCand.Reason = Reason;
2007 if (TryVal > CandVal) {
2008 if (Cand.Reason > Reason)
2009 Cand.Reason = Reason;
2012 Cand.setRepeat(Reason);
2016 static bool tryGreater(int TryVal, int CandVal,
2017 ConvergingScheduler::SchedCandidate &TryCand,
2018 ConvergingScheduler::SchedCandidate &Cand,
2019 ConvergingScheduler::CandReason Reason) {
2020 if (TryVal > CandVal) {
2021 TryCand.Reason = Reason;
2024 if (TryVal < CandVal) {
2025 if (Cand.Reason > Reason)
2026 Cand.Reason = Reason;
2029 Cand.setRepeat(Reason);
2033 static bool tryPressure(const PressureElement &TryP,
2034 const PressureElement &CandP,
2035 ConvergingScheduler::SchedCandidate &TryCand,
2036 ConvergingScheduler::SchedCandidate &Cand,
2037 ConvergingScheduler::CandReason Reason) {
2038 // If both candidates affect the same set, go with the smallest increase.
2039 if (TryP.PSetID == CandP.PSetID) {
2040 return tryLess(TryP.UnitIncrease, CandP.UnitIncrease, TryCand, Cand,
2043 // If one candidate decreases and the other increases, go with it.
2044 if (tryLess(TryP.UnitIncrease < 0, CandP.UnitIncrease < 0, TryCand, Cand,
2048 // If TryP has lower Rank, it has a higher priority.
2049 int TryRank = TryP.PSetRank();
2050 int CandRank = CandP.PSetRank();
2051 // If the candidates are decreasing pressure, reverse priority.
2052 if (TryP.UnitIncrease < 0)
2053 std::swap(TryRank, CandRank);
2054 return tryGreater(TryRank, CandRank, TryCand, Cand, Reason);
2057 static unsigned getWeakLeft(const SUnit *SU, bool isTop) {
2058 return (isTop) ? SU->WeakPredsLeft : SU->WeakSuccsLeft;
2061 /// Minimize physical register live ranges. Regalloc wants them adjacent to
2062 /// their physreg def/use.
2064 /// FIXME: This is an unnecessary check on the critical path. Most are root/leaf
2065 /// copies which can be prescheduled. The rest (e.g. x86 MUL) could be bundled
2066 /// with the operation that produces or consumes the physreg. We'll do this when
2067 /// regalloc has support for parallel copies.
2068 static int biasPhysRegCopy(const SUnit *SU, bool isTop) {
2069 const MachineInstr *MI = SU->getInstr();
2073 unsigned ScheduledOper = isTop ? 1 : 0;
2074 unsigned UnscheduledOper = isTop ? 0 : 1;
2075 // If we have already scheduled the physreg produce/consumer, immediately
2076 // schedule the copy.
2077 if (TargetRegisterInfo::isPhysicalRegister(
2078 MI->getOperand(ScheduledOper).getReg()))
2080 // If the physreg is at the boundary, defer it. Otherwise schedule it
2081 // immediately to free the dependent. We can hoist the copy later.
2082 bool AtBoundary = isTop ? !SU->NumSuccsLeft : !SU->NumPredsLeft;
2083 if (TargetRegisterInfo::isPhysicalRegister(
2084 MI->getOperand(UnscheduledOper).getReg()))
2085 return AtBoundary ? -1 : 1;
2089 /// Apply a set of heursitics to a new candidate. Heuristics are currently
2090 /// hierarchical. This may be more efficient than a graduated cost model because
2091 /// we don't need to evaluate all aspects of the model for each node in the
2092 /// queue. But it's really done to make the heuristics easier to debug and
2093 /// statistically analyze.
2095 /// \param Cand provides the policy and current best candidate.
2096 /// \param TryCand refers to the next SUnit candidate, otherwise uninitialized.
2097 /// \param Zone describes the scheduled zone that we are extending.
2098 /// \param RPTracker describes reg pressure within the scheduled zone.
2099 /// \param TempTracker is a scratch pressure tracker to reuse in queries.
2100 void ConvergingScheduler::tryCandidate(SchedCandidate &Cand,
2101 SchedCandidate &TryCand,
2102 SchedBoundary &Zone,
2103 const RegPressureTracker &RPTracker,
2104 RegPressureTracker &TempTracker) {
2106 // Always initialize TryCand's RPDelta.
2107 TempTracker.getMaxPressureDelta(TryCand.SU->getInstr(), TryCand.RPDelta,
2108 DAG->getRegionCriticalPSets(),
2109 DAG->getRegPressure().MaxSetPressure);
2111 // Initialize the candidate if needed.
2112 if (!Cand.isValid()) {
2113 TryCand.Reason = NodeOrder;
2117 if (tryGreater(biasPhysRegCopy(TryCand.SU, Zone.isTop()),
2118 biasPhysRegCopy(Cand.SU, Zone.isTop()),
2119 TryCand, Cand, PhysRegCopy))
2122 // Avoid exceeding the target's limit. If signed PSetID is negative, it is
2123 // invalid; convert it to INT_MAX to give it lowest priority.
2124 if (tryPressure(TryCand.RPDelta.Excess, Cand.RPDelta.Excess, TryCand, Cand,
2128 // Avoid increasing the max critical pressure in the scheduled region.
2129 if (tryPressure(TryCand.RPDelta.CriticalMax, Cand.RPDelta.CriticalMax,
2130 TryCand, Cand, RegCritical))
2133 // Keep clustered nodes together to encourage downstream peephole
2134 // optimizations which may reduce resource requirements.
2136 // This is a best effort to set things up for a post-RA pass. Optimizations
2137 // like generating loads of multiple registers should ideally be done within
2138 // the scheduler pass by combining the loads during DAG postprocessing.
2139 const SUnit *NextClusterSU =
2140 Zone.isTop() ? DAG->getNextClusterSucc() : DAG->getNextClusterPred();
2141 if (tryGreater(TryCand.SU == NextClusterSU, Cand.SU == NextClusterSU,
2142 TryCand, Cand, Cluster))
2145 // Weak edges are for clustering and other constraints.
2146 if (tryLess(getWeakLeft(TryCand.SU, Zone.isTop()),
2147 getWeakLeft(Cand.SU, Zone.isTop()),
2148 TryCand, Cand, Weak)) {
2151 // Avoid increasing the max pressure of the entire region.
2152 if (tryPressure(TryCand.RPDelta.CurrentMax, Cand.RPDelta.CurrentMax,
2153 TryCand, Cand, RegMax))
2156 // Avoid critical resource consumption and balance the schedule.
2157 TryCand.initResourceDelta(DAG, SchedModel);
2158 if (tryLess(TryCand.ResDelta.CritResources, Cand.ResDelta.CritResources,
2159 TryCand, Cand, ResourceReduce))
2161 if (tryGreater(TryCand.ResDelta.DemandedResources,
2162 Cand.ResDelta.DemandedResources,
2163 TryCand, Cand, ResourceDemand))
2166 // Avoid serializing long latency dependence chains.
2167 if (Cand.Policy.ReduceLatency) {
2169 if (Cand.SU->getDepth() > Zone.getScheduledLatency()) {
2170 if (tryLess(TryCand.SU->getDepth(), Cand.SU->getDepth(),
2171 TryCand, Cand, TopDepthReduce))
2174 if (tryGreater(TryCand.SU->getHeight(), Cand.SU->getHeight(),
2175 TryCand, Cand, TopPathReduce))
2179 if (Cand.SU->getHeight() > Zone.getScheduledLatency()) {
2180 if (tryLess(TryCand.SU->getHeight(), Cand.SU->getHeight(),
2181 TryCand, Cand, BotHeightReduce))
2184 if (tryGreater(TryCand.SU->getDepth(), Cand.SU->getDepth(),
2185 TryCand, Cand, BotPathReduce))
2190 // Prefer immediate defs/users of the last scheduled instruction. This is a
2191 // local pressure avoidance strategy that also makes the machine code
2193 if (tryGreater(Zone.NextSUs.count(TryCand.SU), Zone.NextSUs.count(Cand.SU),
2194 TryCand, Cand, NextDefUse))
2197 // Fall through to original instruction order.
2198 if ((Zone.isTop() && TryCand.SU->NodeNum < Cand.SU->NodeNum)
2199 || (!Zone.isTop() && TryCand.SU->NodeNum > Cand.SU->NodeNum)) {
2200 TryCand.Reason = NodeOrder;
2205 const char *ConvergingScheduler::getReasonStr(
2206 ConvergingScheduler::CandReason Reason) {
2208 case NoCand: return "NOCAND ";
2209 case PhysRegCopy: return "PREG-COPY";
2210 case RegExcess: return "REG-EXCESS";
2211 case RegCritical: return "REG-CRIT ";
2212 case Cluster: return "CLUSTER ";
2213 case Weak: return "WEAK ";
2214 case RegMax: return "REG-MAX ";
2215 case ResourceReduce: return "RES-REDUCE";
2216 case ResourceDemand: return "RES-DEMAND";
2217 case TopDepthReduce: return "TOP-DEPTH ";
2218 case TopPathReduce: return "TOP-PATH ";
2219 case BotHeightReduce:return "BOT-HEIGHT";
2220 case BotPathReduce: return "BOT-PATH ";
2221 case NextDefUse: return "DEF-USE ";
2222 case NodeOrder: return "ORDER ";
2224 llvm_unreachable("Unknown reason!");
2227 void ConvergingScheduler::traceCandidate(const SchedCandidate &Cand) {
2229 unsigned ResIdx = 0;
2230 unsigned Latency = 0;
2231 switch (Cand.Reason) {
2235 P = Cand.RPDelta.Excess;
2238 P = Cand.RPDelta.CriticalMax;
2241 P = Cand.RPDelta.CurrentMax;
2243 case ResourceReduce:
2244 ResIdx = Cand.Policy.ReduceResIdx;
2246 case ResourceDemand:
2247 ResIdx = Cand.Policy.DemandResIdx;
2249 case TopDepthReduce:
2250 Latency = Cand.SU->getDepth();
2253 Latency = Cand.SU->getHeight();
2255 case BotHeightReduce:
2256 Latency = Cand.SU->getHeight();
2259 Latency = Cand.SU->getDepth();
2262 dbgs() << " SU(" << Cand.SU->NodeNum << ") " << getReasonStr(Cand.Reason);
2264 dbgs() << " " << TRI->getRegPressureSetName(P.PSetID)
2265 << ":" << P.UnitIncrease << " ";
2269 dbgs() << " " << SchedModel->getProcResource(ResIdx)->Name << " ";
2273 dbgs() << " " << Latency << " cycles ";
2280 /// Pick the best candidate from the top queue.
2282 /// TODO: getMaxPressureDelta results can be mostly cached for each SUnit during
2283 /// DAG building. To adjust for the current scheduling location we need to
2284 /// maintain the number of vreg uses remaining to be top-scheduled.
2285 void ConvergingScheduler::pickNodeFromQueue(SchedBoundary &Zone,
2286 const RegPressureTracker &RPTracker,
2287 SchedCandidate &Cand) {
2288 ReadyQueue &Q = Zone.Available;
2292 // getMaxPressureDelta temporarily modifies the tracker.
2293 RegPressureTracker &TempTracker = const_cast<RegPressureTracker&>(RPTracker);
2295 for (ReadyQueue::iterator I = Q.begin(), E = Q.end(); I != E; ++I) {
2297 SchedCandidate TryCand(Cand.Policy);
2299 tryCandidate(Cand, TryCand, Zone, RPTracker, TempTracker);
2300 if (TryCand.Reason != NoCand) {
2301 // Initialize resource delta if needed in case future heuristics query it.
2302 if (TryCand.ResDelta == SchedResourceDelta())
2303 TryCand.initResourceDelta(DAG, SchedModel);
2304 Cand.setBest(TryCand);
2305 DEBUG(traceCandidate(Cand));
2310 static void tracePick(const ConvergingScheduler::SchedCandidate &Cand,
2312 DEBUG(dbgs() << "Pick " << (IsTop ? "Top " : "Bot ")
2313 << ConvergingScheduler::getReasonStr(Cand.Reason) << '\n');
2316 /// Pick the best candidate node from either the top or bottom queue.
2317 SUnit *ConvergingScheduler::pickNodeBidirectional(bool &IsTopNode) {
2318 // Schedule as far as possible in the direction of no choice. This is most
2319 // efficient, but also provides the best heuristics for CriticalPSets.
2320 if (SUnit *SU = Bot.pickOnlyChoice()) {
2322 DEBUG(dbgs() << "Pick Bot NOCAND\n");
2325 if (SUnit *SU = Top.pickOnlyChoice()) {
2327 DEBUG(dbgs() << "Pick Top NOCAND\n");
2330 CandPolicy NoPolicy;
2331 SchedCandidate BotCand(NoPolicy);
2332 SchedCandidate TopCand(NoPolicy);
2333 Bot.setPolicy(BotCand.Policy, Top);
2334 Top.setPolicy(TopCand.Policy, Bot);
2336 // Prefer bottom scheduling when heuristics are silent.
2337 pickNodeFromQueue(Bot, DAG->getBotRPTracker(), BotCand);
2338 assert(BotCand.Reason != NoCand && "failed to find the first candidate");
2340 // If either Q has a single candidate that provides the least increase in
2341 // Excess pressure, we can immediately schedule from that Q.
2343 // RegionCriticalPSets summarizes the pressure within the scheduled region and
2344 // affects picking from either Q. If scheduling in one direction must
2345 // increase pressure for one of the excess PSets, then schedule in that
2346 // direction first to provide more freedom in the other direction.
2347 if ((BotCand.Reason == RegExcess && !BotCand.isRepeat(RegExcess))
2348 || (BotCand.Reason == RegCritical
2349 && !BotCand.isRepeat(RegCritical)))
2352 tracePick(BotCand, IsTopNode);
2355 // Check if the top Q has a better candidate.
2356 pickNodeFromQueue(Top, DAG->getTopRPTracker(), TopCand);
2357 assert(TopCand.Reason != NoCand && "failed to find the first candidate");
2359 // Choose the queue with the most important (lowest enum) reason.
2360 if (TopCand.Reason < BotCand.Reason) {
2362 tracePick(TopCand, IsTopNode);
2365 // Otherwise prefer the bottom candidate, in node order if all else failed.
2367 tracePick(BotCand, IsTopNode);
2371 /// Pick the best node to balance the schedule. Implements MachineSchedStrategy.
2372 SUnit *ConvergingScheduler::pickNode(bool &IsTopNode) {
2373 if (DAG->top() == DAG->bottom()) {
2374 assert(Top.Available.empty() && Top.Pending.empty() &&
2375 Bot.Available.empty() && Bot.Pending.empty() && "ReadyQ garbage");
2381 SU = Top.pickOnlyChoice();
2383 CandPolicy NoPolicy;
2384 SchedCandidate TopCand(NoPolicy);
2385 pickNodeFromQueue(Top, DAG->getTopRPTracker(), TopCand);
2386 assert(TopCand.Reason != NoCand && "failed to find the first candidate");
2391 else if (ForceBottomUp) {
2392 SU = Bot.pickOnlyChoice();
2394 CandPolicy NoPolicy;
2395 SchedCandidate BotCand(NoPolicy);
2396 pickNodeFromQueue(Bot, DAG->getBotRPTracker(), BotCand);
2397 assert(BotCand.Reason != NoCand && "failed to find the first candidate");
2403 SU = pickNodeBidirectional(IsTopNode);
2405 } while (SU->isScheduled);
2407 if (SU->isTopReady())
2408 Top.removeReady(SU);
2409 if (SU->isBottomReady())
2410 Bot.removeReady(SU);
2412 DEBUG(dbgs() << "Scheduling SU(" << SU->NodeNum << ") " << *SU->getInstr());
2416 void ConvergingScheduler::reschedulePhysRegCopies(SUnit *SU, bool isTop) {
2418 MachineBasicBlock::iterator InsertPos = SU->getInstr();
2421 SmallVectorImpl<SDep> &Deps = isTop ? SU->Preds : SU->Succs;
2423 // Find already scheduled copies with a single physreg dependence and move
2424 // them just above the scheduled instruction.
2425 for (SmallVectorImpl<SDep>::iterator I = Deps.begin(), E = Deps.end();
2427 if (I->getKind() != SDep::Data || !TRI->isPhysicalRegister(I->getReg()))
2429 SUnit *DepSU = I->getSUnit();
2430 if (isTop ? DepSU->Succs.size() > 1 : DepSU->Preds.size() > 1)
2432 MachineInstr *Copy = DepSU->getInstr();
2433 if (!Copy->isCopy())
2435 DEBUG(dbgs() << " Rescheduling physreg copy ";
2436 I->getSUnit()->dump(DAG));
2437 DAG->moveInstruction(Copy, InsertPos);
2441 /// Update the scheduler's state after scheduling a node. This is the same node
2442 /// that was just returned by pickNode(). However, ScheduleDAGMI needs to update
2443 /// it's state based on the current cycle before MachineSchedStrategy does.
2445 /// FIXME: Eventually, we may bundle physreg copies rather than rescheduling
2446 /// them here. See comments in biasPhysRegCopy.
2447 void ConvergingScheduler::schedNode(SUnit *SU, bool IsTopNode) {
2449 SU->TopReadyCycle = std::max(SU->TopReadyCycle, Top.CurrCycle);
2451 if (SU->hasPhysRegUses)
2452 reschedulePhysRegCopies(SU, true);
2455 SU->BotReadyCycle = std::max(SU->BotReadyCycle, Bot.CurrCycle);
2457 if (SU->hasPhysRegDefs)
2458 reschedulePhysRegCopies(SU, false);
2462 /// Create the standard converging machine scheduler. This will be used as the
2463 /// default scheduler if the target does not set a default.
2464 static ScheduleDAGInstrs *createConvergingSched(MachineSchedContext *C) {
2465 assert((!ForceTopDown || !ForceBottomUp) &&
2466 "-misched-topdown incompatible with -misched-bottomup");
2467 ScheduleDAGMI *DAG = new ScheduleDAGMI(C, new ConvergingScheduler());
2468 // Register DAG post-processors.
2470 // FIXME: extend the mutation API to allow earlier mutations to instantiate
2471 // data and pass it to later mutations. Have a single mutation that gathers
2472 // the interesting nodes in one pass.
2473 DAG->addMutation(new CopyConstrain(DAG->TII, DAG->TRI));
2474 if (EnableLoadCluster)
2475 DAG->addMutation(new LoadClusterMutation(DAG->TII, DAG->TRI));
2476 if (EnableMacroFusion)
2477 DAG->addMutation(new MacroFusion(DAG->TII));
2480 static MachineSchedRegistry
2481 ConvergingSchedRegistry("converge", "Standard converging scheduler.",
2482 createConvergingSched);
2484 //===----------------------------------------------------------------------===//
2485 // ILP Scheduler. Currently for experimental analysis of heuristics.
2486 //===----------------------------------------------------------------------===//
2489 /// \brief Order nodes by the ILP metric.
2491 const SchedDFSResult *DFSResult;
2492 const BitVector *ScheduledTrees;
2495 ILPOrder(bool MaxILP): DFSResult(0), ScheduledTrees(0), MaximizeILP(MaxILP) {}
2497 /// \brief Apply a less-than relation on node priority.
2499 /// (Return true if A comes after B in the Q.)
2500 bool operator()(const SUnit *A, const SUnit *B) const {
2501 unsigned SchedTreeA = DFSResult->getSubtreeID(A);
2502 unsigned SchedTreeB = DFSResult->getSubtreeID(B);
2503 if (SchedTreeA != SchedTreeB) {
2504 // Unscheduled trees have lower priority.
2505 if (ScheduledTrees->test(SchedTreeA) != ScheduledTrees->test(SchedTreeB))
2506 return ScheduledTrees->test(SchedTreeB);
2508 // Trees with shallower connections have have lower priority.
2509 if (DFSResult->getSubtreeLevel(SchedTreeA)
2510 != DFSResult->getSubtreeLevel(SchedTreeB)) {
2511 return DFSResult->getSubtreeLevel(SchedTreeA)
2512 < DFSResult->getSubtreeLevel(SchedTreeB);
2516 return DFSResult->getILP(A) < DFSResult->getILP(B);
2518 return DFSResult->getILP(A) > DFSResult->getILP(B);
2522 /// \brief Schedule based on the ILP metric.
2523 class ILPScheduler : public MachineSchedStrategy {
2524 /// In case all subtrees are eventually connected to a common root through
2525 /// data dependence (e.g. reduction), place an upper limit on their size.
2527 /// FIXME: A subtree limit is generally good, but in the situation commented
2528 /// above, where multiple similar subtrees feed a common root, we should
2529 /// only split at a point where the resulting subtrees will be balanced.
2530 /// (a motivating test case must be found).
2531 static const unsigned SubtreeLimit = 16;
2536 std::vector<SUnit*> ReadyQ;
2538 ILPScheduler(bool MaximizeILP): DAG(0), Cmp(MaximizeILP) {}
2540 virtual void initialize(ScheduleDAGMI *dag) {
2542 DAG->computeDFSResult();
2543 Cmp.DFSResult = DAG->getDFSResult();
2544 Cmp.ScheduledTrees = &DAG->getScheduledTrees();
2548 virtual void registerRoots() {
2549 // Restore the heap in ReadyQ with the updated DFS results.
2550 std::make_heap(ReadyQ.begin(), ReadyQ.end(), Cmp);
2553 /// Implement MachineSchedStrategy interface.
2554 /// -----------------------------------------
2556 /// Callback to select the highest priority node from the ready Q.
2557 virtual SUnit *pickNode(bool &IsTopNode) {
2558 if (ReadyQ.empty()) return NULL;
2559 std::pop_heap(ReadyQ.begin(), ReadyQ.end(), Cmp);
2560 SUnit *SU = ReadyQ.back();
2563 DEBUG(dbgs() << "Pick node " << "SU(" << SU->NodeNum << ") "
2564 << " ILP: " << DAG->getDFSResult()->getILP(SU)
2565 << " Tree: " << DAG->getDFSResult()->getSubtreeID(SU) << " @"
2566 << DAG->getDFSResult()->getSubtreeLevel(
2567 DAG->getDFSResult()->getSubtreeID(SU)) << '\n'
2568 << "Scheduling " << *SU->getInstr());
2572 /// \brief Scheduler callback to notify that a new subtree is scheduled.
2573 virtual void scheduleTree(unsigned SubtreeID) {
2574 std::make_heap(ReadyQ.begin(), ReadyQ.end(), Cmp);
2577 /// Callback after a node is scheduled. Mark a newly scheduled tree, notify
2578 /// DFSResults, and resort the priority Q.
2579 virtual void schedNode(SUnit *SU, bool IsTopNode) {
2580 assert(!IsTopNode && "SchedDFSResult needs bottom-up");
2583 virtual void releaseTopNode(SUnit *) { /*only called for top roots*/ }
2585 virtual void releaseBottomNode(SUnit *SU) {
2586 ReadyQ.push_back(SU);
2587 std::push_heap(ReadyQ.begin(), ReadyQ.end(), Cmp);
2592 static ScheduleDAGInstrs *createILPMaxScheduler(MachineSchedContext *C) {
2593 return new ScheduleDAGMI(C, new ILPScheduler(true));
2595 static ScheduleDAGInstrs *createILPMinScheduler(MachineSchedContext *C) {
2596 return new ScheduleDAGMI(C, new ILPScheduler(false));
2598 static MachineSchedRegistry ILPMaxRegistry(
2599 "ilpmax", "Schedule bottom-up for max ILP", createILPMaxScheduler);
2600 static MachineSchedRegistry ILPMinRegistry(
2601 "ilpmin", "Schedule bottom-up for min ILP", createILPMinScheduler);
2603 //===----------------------------------------------------------------------===//
2604 // Machine Instruction Shuffler for Correctness Testing
2605 //===----------------------------------------------------------------------===//
2609 /// Apply a less-than relation on the node order, which corresponds to the
2610 /// instruction order prior to scheduling. IsReverse implements greater-than.
2611 template<bool IsReverse>
2613 bool operator()(SUnit *A, SUnit *B) const {
2615 return A->NodeNum > B->NodeNum;
2617 return A->NodeNum < B->NodeNum;
2621 /// Reorder instructions as much as possible.
2622 class InstructionShuffler : public MachineSchedStrategy {
2626 // Using a less-than relation (SUnitOrder<false>) for the TopQ priority
2627 // gives nodes with a higher number higher priority causing the latest
2628 // instructions to be scheduled first.
2629 PriorityQueue<SUnit*, std::vector<SUnit*>, SUnitOrder<false> >
2631 // When scheduling bottom-up, use greater-than as the queue priority.
2632 PriorityQueue<SUnit*, std::vector<SUnit*>, SUnitOrder<true> >
2635 InstructionShuffler(bool alternate, bool topdown)
2636 : IsAlternating(alternate), IsTopDown(topdown) {}
2638 virtual void initialize(ScheduleDAGMI *) {
2643 /// Implement MachineSchedStrategy interface.
2644 /// -----------------------------------------
2646 virtual SUnit *pickNode(bool &IsTopNode) {
2650 if (TopQ.empty()) return NULL;
2653 } while (SU->isScheduled);
2658 if (BottomQ.empty()) return NULL;
2661 } while (SU->isScheduled);
2665 IsTopDown = !IsTopDown;
2669 virtual void schedNode(SUnit *SU, bool IsTopNode) {}
2671 virtual void releaseTopNode(SUnit *SU) {
2674 virtual void releaseBottomNode(SUnit *SU) {
2680 static ScheduleDAGInstrs *createInstructionShuffler(MachineSchedContext *C) {
2681 bool Alternate = !ForceTopDown && !ForceBottomUp;
2682 bool TopDown = !ForceBottomUp;
2683 assert((TopDown || !ForceTopDown) &&
2684 "-misched-topdown incompatible with -misched-bottomup");
2685 return new ScheduleDAGMI(C, new InstructionShuffler(Alternate, TopDown));
2687 static MachineSchedRegistry ShufflerRegistry(
2688 "shuffle", "Shuffle machine instructions alternating directions",
2689 createInstructionShuffler);
2692 //===----------------------------------------------------------------------===//
2693 // GraphWriter support for ScheduleDAGMI.
2694 //===----------------------------------------------------------------------===//
2699 template<> struct GraphTraits<
2700 ScheduleDAGMI*> : public GraphTraits<ScheduleDAG*> {};
2703 struct DOTGraphTraits<ScheduleDAGMI*> : public DefaultDOTGraphTraits {
2705 DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {}
2707 static std::string getGraphName(const ScheduleDAG *G) {
2708 return G->MF.getName();
2711 static bool renderGraphFromBottomUp() {
2715 static bool isNodeHidden(const SUnit *Node) {
2716 return (Node->NumPreds > 10 || Node->NumSuccs > 10);
2719 static bool hasNodeAddressLabel(const SUnit *Node,
2720 const ScheduleDAG *Graph) {
2724 /// If you want to override the dot attributes printed for a particular
2725 /// edge, override this method.
2726 static std::string getEdgeAttributes(const SUnit *Node,
2728 const ScheduleDAG *Graph) {
2729 if (EI.isArtificialDep())
2730 return "color=cyan,style=dashed";
2732 return "color=blue,style=dashed";
2736 static std::string getNodeLabel(const SUnit *SU, const ScheduleDAG *G) {
2738 raw_string_ostream SS(Str);
2739 SS << "SU(" << SU->NodeNum << ')';
2742 static std::string getNodeDescription(const SUnit *SU, const ScheduleDAG *G) {
2743 return G->getGraphNodeLabel(SU);
2746 static std::string getNodeAttributes(const SUnit *N,
2747 const ScheduleDAG *Graph) {
2748 std::string Str("shape=Mrecord");
2749 const SchedDFSResult *DFS =
2750 static_cast<const ScheduleDAGMI*>(Graph)->getDFSResult();
2752 Str += ",style=filled,fillcolor=\"#";
2753 Str += DOT::getColorString(DFS->getSubtreeID(N));
2762 /// viewGraph - Pop up a ghostview window with the reachable parts of the DAG
2763 /// rendered using 'dot'.
2765 void ScheduleDAGMI::viewGraph(const Twine &Name, const Twine &Title) {
2767 ViewGraph(this, Name, false, Title);
2769 errs() << "ScheduleDAGMI::viewGraph is only available in debug builds on "
2770 << "systems with Graphviz or gv!\n";
2774 /// Out-of-line implementation with no arguments is handy for gdb.
2775 void ScheduleDAGMI::viewGraph() {
2776 viewGraph(getDAGName(), "Scheduling-Units Graph for " + getDAGName());