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Diffstat (limited to 'contrib/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp')
| -rw-r--r-- | contrib/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp | 804 |
1 files changed, 804 insertions, 0 deletions
diff --git a/contrib/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp b/contrib/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp new file mode 100644 index 000000000000..90e109b022fd --- /dev/null +++ b/contrib/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGFast.cpp @@ -0,0 +1,804 @@ +//===----- ScheduleDAGFast.cpp - Fast poor list scheduler -----------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This implements a fast scheduler. +// +//===----------------------------------------------------------------------===// + +#include "InstrEmitter.h" +#include "ScheduleDAGSDNodes.h" +#include "SDNodeDbgValue.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/SmallSet.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/CodeGen/SchedulerRegistry.h" +#include "llvm/CodeGen/SelectionDAGISel.h" +#include "llvm/CodeGen/TargetInstrInfo.h" +#include "llvm/CodeGen/TargetRegisterInfo.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/InlineAsm.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/raw_ostream.h" +using namespace llvm; + +#define DEBUG_TYPE "pre-RA-sched" + +STATISTIC(NumUnfolds, "Number of nodes unfolded"); +STATISTIC(NumDups, "Number of duplicated nodes"); +STATISTIC(NumPRCopies, "Number of physical copies"); + +static RegisterScheduler + fastDAGScheduler("fast", "Fast suboptimal list scheduling", + createFastDAGScheduler); +static RegisterScheduler + linearizeDAGScheduler("linearize", "Linearize DAG, no scheduling", + createDAGLinearizer); + + +namespace { + /// FastPriorityQueue - A degenerate priority queue that considers + /// all nodes to have the same priority. + /// + struct FastPriorityQueue { + SmallVector<SUnit *, 16> Queue; + + bool empty() const { return Queue.empty(); } + + void push(SUnit *U) { + Queue.push_back(U); + } + + SUnit *pop() { + if (empty()) return nullptr; + SUnit *V = Queue.back(); + Queue.pop_back(); + return V; + } + }; + +//===----------------------------------------------------------------------===// +/// ScheduleDAGFast - The actual "fast" list scheduler implementation. +/// +class ScheduleDAGFast : public ScheduleDAGSDNodes { +private: + /// AvailableQueue - The priority queue to use for the available SUnits. + FastPriorityQueue AvailableQueue; + + /// LiveRegDefs - A set of physical registers and their definition + /// that are "live". These nodes must be scheduled before any other nodes that + /// modifies the registers can be scheduled. + unsigned NumLiveRegs; + std::vector<SUnit*> LiveRegDefs; + std::vector<unsigned> LiveRegCycles; + +public: + ScheduleDAGFast(MachineFunction &mf) + : ScheduleDAGSDNodes(mf) {} + + void Schedule() override; + + /// AddPred - adds a predecessor edge to SUnit SU. + /// This returns true if this is a new predecessor. + void AddPred(SUnit *SU, const SDep &D) { + SU->addPred(D); + } + + /// RemovePred - removes a predecessor edge from SUnit SU. + /// This returns true if an edge was removed. + void RemovePred(SUnit *SU, const SDep &D) { + SU->removePred(D); + } + +private: + void ReleasePred(SUnit *SU, SDep *PredEdge); + void ReleasePredecessors(SUnit *SU, unsigned CurCycle); + void ScheduleNodeBottomUp(SUnit*, unsigned); + SUnit *CopyAndMoveSuccessors(SUnit*); + void InsertCopiesAndMoveSuccs(SUnit*, unsigned, + const TargetRegisterClass*, + const TargetRegisterClass*, + SmallVectorImpl<SUnit*>&); + bool DelayForLiveRegsBottomUp(SUnit*, SmallVectorImpl<unsigned>&); + void ListScheduleBottomUp(); + + /// forceUnitLatencies - The fast scheduler doesn't care about real latencies. + bool forceUnitLatencies() const override { return true; } +}; +} // end anonymous namespace + + +/// Schedule - Schedule the DAG using list scheduling. +void ScheduleDAGFast::Schedule() { + LLVM_DEBUG(dbgs() << "********** List Scheduling **********\n"); + + NumLiveRegs = 0; + LiveRegDefs.resize(TRI->getNumRegs(), nullptr); + LiveRegCycles.resize(TRI->getNumRegs(), 0); + + // Build the scheduling graph. + BuildSchedGraph(nullptr); + + LLVM_DEBUG(dump()); + + // Execute the actual scheduling loop. + ListScheduleBottomUp(); +} + +//===----------------------------------------------------------------------===// +// Bottom-Up Scheduling +//===----------------------------------------------------------------------===// + +/// ReleasePred - Decrement the NumSuccsLeft count of a predecessor. Add it to +/// the AvailableQueue if the count reaches zero. Also update its cycle bound. +void ScheduleDAGFast::ReleasePred(SUnit *SU, SDep *PredEdge) { + SUnit *PredSU = PredEdge->getSUnit(); + +#ifndef NDEBUG + if (PredSU->NumSuccsLeft == 0) { + dbgs() << "*** Scheduling failed! ***\n"; + dumpNode(*PredSU); + dbgs() << " has been released too many times!\n"; + llvm_unreachable(nullptr); + } +#endif + --PredSU->NumSuccsLeft; + + // If all the node's successors are scheduled, this node is ready + // to be scheduled. Ignore the special EntrySU node. + if (PredSU->NumSuccsLeft == 0 && PredSU != &EntrySU) { + PredSU->isAvailable = true; + AvailableQueue.push(PredSU); + } +} + +void ScheduleDAGFast::ReleasePredecessors(SUnit *SU, unsigned CurCycle) { + // Bottom up: release predecessors + for (SDep &Pred : SU->Preds) { + ReleasePred(SU, &Pred); + if (Pred.isAssignedRegDep()) { + // This is a physical register dependency and it's impossible or + // expensive to copy the register. Make sure nothing that can + // clobber the register is scheduled between the predecessor and + // this node. + if (!LiveRegDefs[Pred.getReg()]) { + ++NumLiveRegs; + LiveRegDefs[Pred.getReg()] = Pred.getSUnit(); + LiveRegCycles[Pred.getReg()] = CurCycle; + } + } + } +} + +/// ScheduleNodeBottomUp - Add the node to the schedule. Decrement the pending +/// count of its predecessors. If a predecessor pending count is zero, add it to +/// the Available queue. +void ScheduleDAGFast::ScheduleNodeBottomUp(SUnit *SU, unsigned CurCycle) { + LLVM_DEBUG(dbgs() << "*** Scheduling [" << CurCycle << "]: "); + LLVM_DEBUG(dumpNode(*SU)); + + assert(CurCycle >= SU->getHeight() && "Node scheduled below its height!"); + SU->setHeightToAtLeast(CurCycle); + Sequence.push_back(SU); + + ReleasePredecessors(SU, CurCycle); + + // Release all the implicit physical register defs that are live. + for (SDep &Succ : SU->Succs) { + if (Succ.isAssignedRegDep()) { + if (LiveRegCycles[Succ.getReg()] == Succ.getSUnit()->getHeight()) { + assert(NumLiveRegs > 0 && "NumLiveRegs is already zero!"); + assert(LiveRegDefs[Succ.getReg()] == SU && + "Physical register dependency violated?"); + --NumLiveRegs; + LiveRegDefs[Succ.getReg()] = nullptr; + LiveRegCycles[Succ.getReg()] = 0; + } + } + } + + SU->isScheduled = true; +} + +/// CopyAndMoveSuccessors - Clone the specified node and move its scheduled +/// successors to the newly created node. +SUnit *ScheduleDAGFast::CopyAndMoveSuccessors(SUnit *SU) { + if (SU->getNode()->getGluedNode()) + return nullptr; + + SDNode *N = SU->getNode(); + if (!N) + return nullptr; + + SUnit *NewSU; + bool TryUnfold = false; + for (unsigned i = 0, e = N->getNumValues(); i != e; ++i) { + MVT VT = N->getSimpleValueType(i); + if (VT == MVT::Glue) + return nullptr; + else if (VT == MVT::Other) + TryUnfold = true; + } + for (const SDValue &Op : N->op_values()) { + MVT VT = Op.getNode()->getSimpleValueType(Op.getResNo()); + if (VT == MVT::Glue) + return nullptr; + } + + if (TryUnfold) { + SmallVector<SDNode*, 2> NewNodes; + if (!TII->unfoldMemoryOperand(*DAG, N, NewNodes)) + return nullptr; + + LLVM_DEBUG(dbgs() << "Unfolding SU # " << SU->NodeNum << "\n"); + assert(NewNodes.size() == 2 && "Expected a load folding node!"); + + N = NewNodes[1]; + SDNode *LoadNode = NewNodes[0]; + unsigned NumVals = N->getNumValues(); + unsigned OldNumVals = SU->getNode()->getNumValues(); + for (unsigned i = 0; i != NumVals; ++i) + DAG->ReplaceAllUsesOfValueWith(SDValue(SU->getNode(), i), SDValue(N, i)); + DAG->ReplaceAllUsesOfValueWith(SDValue(SU->getNode(), OldNumVals-1), + SDValue(LoadNode, 1)); + + SUnit *NewSU = newSUnit(N); + assert(N->getNodeId() == -1 && "Node already inserted!"); + N->setNodeId(NewSU->NodeNum); + + const MCInstrDesc &MCID = TII->get(N->getMachineOpcode()); + for (unsigned i = 0; i != MCID.getNumOperands(); ++i) { + if (MCID.getOperandConstraint(i, MCOI::TIED_TO) != -1) { + NewSU->isTwoAddress = true; + break; + } + } + if (MCID.isCommutable()) + NewSU->isCommutable = true; + + // LoadNode may already exist. This can happen when there is another + // load from the same location and producing the same type of value + // but it has different alignment or volatileness. + bool isNewLoad = true; + SUnit *LoadSU; + if (LoadNode->getNodeId() != -1) { + LoadSU = &SUnits[LoadNode->getNodeId()]; + isNewLoad = false; + } else { + LoadSU = newSUnit(LoadNode); + LoadNode->setNodeId(LoadSU->NodeNum); + } + + SDep ChainPred; + SmallVector<SDep, 4> ChainSuccs; + SmallVector<SDep, 4> LoadPreds; + SmallVector<SDep, 4> NodePreds; + SmallVector<SDep, 4> NodeSuccs; + for (SDep &Pred : SU->Preds) { + if (Pred.isCtrl()) + ChainPred = Pred; + else if (Pred.getSUnit()->getNode() && + Pred.getSUnit()->getNode()->isOperandOf(LoadNode)) + LoadPreds.push_back(Pred); + else + NodePreds.push_back(Pred); + } + for (SDep &Succ : SU->Succs) { + if (Succ.isCtrl()) + ChainSuccs.push_back(Succ); + else + NodeSuccs.push_back(Succ); + } + + if (ChainPred.getSUnit()) { + RemovePred(SU, ChainPred); + if (isNewLoad) + AddPred(LoadSU, ChainPred); + } + for (unsigned i = 0, e = LoadPreds.size(); i != e; ++i) { + const SDep &Pred = LoadPreds[i]; + RemovePred(SU, Pred); + if (isNewLoad) { + AddPred(LoadSU, Pred); + } + } + for (unsigned i = 0, e = NodePreds.size(); i != e; ++i) { + const SDep &Pred = NodePreds[i]; + RemovePred(SU, Pred); + AddPred(NewSU, Pred); + } + for (unsigned i = 0, e = NodeSuccs.size(); i != e; ++i) { + SDep D = NodeSuccs[i]; + SUnit *SuccDep = D.getSUnit(); + D.setSUnit(SU); + RemovePred(SuccDep, D); + D.setSUnit(NewSU); + AddPred(SuccDep, D); + } + for (unsigned i = 0, e = ChainSuccs.size(); i != e; ++i) { + SDep D = ChainSuccs[i]; + SUnit *SuccDep = D.getSUnit(); + D.setSUnit(SU); + RemovePred(SuccDep, D); + if (isNewLoad) { + D.setSUnit(LoadSU); + AddPred(SuccDep, D); + } + } + if (isNewLoad) { + SDep D(LoadSU, SDep::Barrier); + D.setLatency(LoadSU->Latency); + AddPred(NewSU, D); + } + + ++NumUnfolds; + + if (NewSU->NumSuccsLeft == 0) { + NewSU->isAvailable = true; + return NewSU; + } + SU = NewSU; + } + + LLVM_DEBUG(dbgs() << "Duplicating SU # " << SU->NodeNum << "\n"); + NewSU = Clone(SU); + + // New SUnit has the exact same predecessors. + for (SDep &Pred : SU->Preds) + if (!Pred.isArtificial()) + AddPred(NewSU, Pred); + + // Only copy scheduled successors. Cut them from old node's successor + // list and move them over. + SmallVector<std::pair<SUnit *, SDep>, 4> DelDeps; + for (SDep &Succ : SU->Succs) { + if (Succ.isArtificial()) + continue; + SUnit *SuccSU = Succ.getSUnit(); + if (SuccSU->isScheduled) { + SDep D = Succ; + D.setSUnit(NewSU); + AddPred(SuccSU, D); + D.setSUnit(SU); + DelDeps.push_back(std::make_pair(SuccSU, D)); + } + } + for (unsigned i = 0, e = DelDeps.size(); i != e; ++i) + RemovePred(DelDeps[i].first, DelDeps[i].second); + + ++NumDups; + return NewSU; +} + +/// InsertCopiesAndMoveSuccs - Insert register copies and move all +/// scheduled successors of the given SUnit to the last copy. +void ScheduleDAGFast::InsertCopiesAndMoveSuccs(SUnit *SU, unsigned Reg, + const TargetRegisterClass *DestRC, + const TargetRegisterClass *SrcRC, + SmallVectorImpl<SUnit*> &Copies) { + SUnit *CopyFromSU = newSUnit(static_cast<SDNode *>(nullptr)); + CopyFromSU->CopySrcRC = SrcRC; + CopyFromSU->CopyDstRC = DestRC; + + SUnit *CopyToSU = newSUnit(static_cast<SDNode *>(nullptr)); + CopyToSU->CopySrcRC = DestRC; + CopyToSU->CopyDstRC = SrcRC; + + // Only copy scheduled successors. Cut them from old node's successor + // list and move them over. + SmallVector<std::pair<SUnit *, SDep>, 4> DelDeps; + for (SDep &Succ : SU->Succs) { + if (Succ.isArtificial()) + continue; + SUnit *SuccSU = Succ.getSUnit(); + if (SuccSU->isScheduled) { + SDep D = Succ; + D.setSUnit(CopyToSU); + AddPred(SuccSU, D); + DelDeps.push_back(std::make_pair(SuccSU, Succ)); + } + } + for (unsigned i = 0, e = DelDeps.size(); i != e; ++i) { + RemovePred(DelDeps[i].first, DelDeps[i].second); + } + SDep FromDep(SU, SDep::Data, Reg); + FromDep.setLatency(SU->Latency); + AddPred(CopyFromSU, FromDep); + SDep ToDep(CopyFromSU, SDep::Data, 0); + ToDep.setLatency(CopyFromSU->Latency); + AddPred(CopyToSU, ToDep); + + Copies.push_back(CopyFromSU); + Copies.push_back(CopyToSU); + + ++NumPRCopies; +} + +/// getPhysicalRegisterVT - Returns the ValueType of the physical register +/// definition of the specified node. +/// FIXME: Move to SelectionDAG? +static MVT getPhysicalRegisterVT(SDNode *N, unsigned Reg, + const TargetInstrInfo *TII) { + unsigned NumRes; + if (N->getOpcode() == ISD::CopyFromReg) { + // CopyFromReg has: "chain, Val, glue" so operand 1 gives the type. + NumRes = 1; + } else { + const MCInstrDesc &MCID = TII->get(N->getMachineOpcode()); + assert(MCID.ImplicitDefs && "Physical reg def must be in implicit def list!"); + NumRes = MCID.getNumDefs(); + for (const MCPhysReg *ImpDef = MCID.getImplicitDefs(); *ImpDef; ++ImpDef) { + if (Reg == *ImpDef) + break; + ++NumRes; + } + } + return N->getSimpleValueType(NumRes); +} + +/// CheckForLiveRegDef - Return true and update live register vector if the +/// specified register def of the specified SUnit clobbers any "live" registers. +static bool CheckForLiveRegDef(SUnit *SU, unsigned Reg, + std::vector<SUnit*> &LiveRegDefs, + SmallSet<unsigned, 4> &RegAdded, + SmallVectorImpl<unsigned> &LRegs, + const TargetRegisterInfo *TRI) { + bool Added = false; + for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI) { + if (LiveRegDefs[*AI] && LiveRegDefs[*AI] != SU) { + if (RegAdded.insert(*AI).second) { + LRegs.push_back(*AI); + Added = true; + } + } + } + return Added; +} + +/// DelayForLiveRegsBottomUp - Returns true if it is necessary to delay +/// scheduling of the given node to satisfy live physical register dependencies. +/// If the specific node is the last one that's available to schedule, do +/// whatever is necessary (i.e. backtracking or cloning) to make it possible. +bool ScheduleDAGFast::DelayForLiveRegsBottomUp(SUnit *SU, + SmallVectorImpl<unsigned> &LRegs){ + if (NumLiveRegs == 0) + return false; + + SmallSet<unsigned, 4> RegAdded; + // If this node would clobber any "live" register, then it's not ready. + for (SDep &Pred : SU->Preds) { + if (Pred.isAssignedRegDep()) { + CheckForLiveRegDef(Pred.getSUnit(), Pred.getReg(), LiveRegDefs, + RegAdded, LRegs, TRI); + } + } + + for (SDNode *Node = SU->getNode(); Node; Node = Node->getGluedNode()) { + if (Node->getOpcode() == ISD::INLINEASM) { + // Inline asm can clobber physical defs. + unsigned NumOps = Node->getNumOperands(); + if (Node->getOperand(NumOps-1).getValueType() == MVT::Glue) + --NumOps; // Ignore the glue operand. + + for (unsigned i = InlineAsm::Op_FirstOperand; i != NumOps;) { + unsigned Flags = + cast<ConstantSDNode>(Node->getOperand(i))->getZExtValue(); + unsigned NumVals = InlineAsm::getNumOperandRegisters(Flags); + + ++i; // Skip the ID value. + if (InlineAsm::isRegDefKind(Flags) || + InlineAsm::isRegDefEarlyClobberKind(Flags) || + InlineAsm::isClobberKind(Flags)) { + // Check for def of register or earlyclobber register. + for (; NumVals; --NumVals, ++i) { + unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg(); + if (TargetRegisterInfo::isPhysicalRegister(Reg)) + CheckForLiveRegDef(SU, Reg, LiveRegDefs, RegAdded, LRegs, TRI); + } + } else + i += NumVals; + } + continue; + } + if (!Node->isMachineOpcode()) + continue; + const MCInstrDesc &MCID = TII->get(Node->getMachineOpcode()); + if (!MCID.ImplicitDefs) + continue; + for (const MCPhysReg *Reg = MCID.getImplicitDefs(); *Reg; ++Reg) { + CheckForLiveRegDef(SU, *Reg, LiveRegDefs, RegAdded, LRegs, TRI); + } + } + return !LRegs.empty(); +} + + +/// ListScheduleBottomUp - The main loop of list scheduling for bottom-up +/// schedulers. +void ScheduleDAGFast::ListScheduleBottomUp() { + unsigned CurCycle = 0; + + // Release any predecessors of the special Exit node. + ReleasePredecessors(&ExitSU, CurCycle); + + // Add root to Available queue. + if (!SUnits.empty()) { + SUnit *RootSU = &SUnits[DAG->getRoot().getNode()->getNodeId()]; + assert(RootSU->Succs.empty() && "Graph root shouldn't have successors!"); + RootSU->isAvailable = true; + AvailableQueue.push(RootSU); + } + + // While Available queue is not empty, grab the node with the highest + // priority. If it is not ready put it back. Schedule the node. + SmallVector<SUnit*, 4> NotReady; + DenseMap<SUnit*, SmallVector<unsigned, 4> > LRegsMap; + Sequence.reserve(SUnits.size()); + while (!AvailableQueue.empty()) { + bool Delayed = false; + LRegsMap.clear(); + SUnit *CurSU = AvailableQueue.pop(); + while (CurSU) { + SmallVector<unsigned, 4> LRegs; + if (!DelayForLiveRegsBottomUp(CurSU, LRegs)) + break; + Delayed = true; + LRegsMap.insert(std::make_pair(CurSU, LRegs)); + + CurSU->isPending = true; // This SU is not in AvailableQueue right now. + NotReady.push_back(CurSU); + CurSU = AvailableQueue.pop(); + } + + // All candidates are delayed due to live physical reg dependencies. + // Try code duplication or inserting cross class copies + // to resolve it. + if (Delayed && !CurSU) { + if (!CurSU) { + // Try duplicating the nodes that produces these + // "expensive to copy" values to break the dependency. In case even + // that doesn't work, insert cross class copies. + SUnit *TrySU = NotReady[0]; + SmallVectorImpl<unsigned> &LRegs = LRegsMap[TrySU]; + assert(LRegs.size() == 1 && "Can't handle this yet!"); + unsigned Reg = LRegs[0]; + SUnit *LRDef = LiveRegDefs[Reg]; + MVT VT = getPhysicalRegisterVT(LRDef->getNode(), Reg, TII); + const TargetRegisterClass *RC = + TRI->getMinimalPhysRegClass(Reg, VT); + const TargetRegisterClass *DestRC = TRI->getCrossCopyRegClass(RC); + + // If cross copy register class is the same as RC, then it must be + // possible copy the value directly. Do not try duplicate the def. + // If cross copy register class is not the same as RC, then it's + // possible to copy the value but it require cross register class copies + // and it is expensive. + // If cross copy register class is null, then it's not possible to copy + // the value at all. + SUnit *NewDef = nullptr; + if (DestRC != RC) { + NewDef = CopyAndMoveSuccessors(LRDef); + if (!DestRC && !NewDef) + report_fatal_error("Can't handle live physical " + "register dependency!"); + } + if (!NewDef) { + // Issue copies, these can be expensive cross register class copies. + SmallVector<SUnit*, 2> Copies; + InsertCopiesAndMoveSuccs(LRDef, Reg, DestRC, RC, Copies); + LLVM_DEBUG(dbgs() << "Adding an edge from SU # " << TrySU->NodeNum + << " to SU #" << Copies.front()->NodeNum << "\n"); + AddPred(TrySU, SDep(Copies.front(), SDep::Artificial)); + NewDef = Copies.back(); + } + + LLVM_DEBUG(dbgs() << "Adding an edge from SU # " << NewDef->NodeNum + << " to SU #" << TrySU->NodeNum << "\n"); + LiveRegDefs[Reg] = NewDef; + AddPred(NewDef, SDep(TrySU, SDep::Artificial)); + TrySU->isAvailable = false; + CurSU = NewDef; + } + + if (!CurSU) { + llvm_unreachable("Unable to resolve live physical register dependencies!"); + } + } + + // Add the nodes that aren't ready back onto the available list. + for (unsigned i = 0, e = NotReady.size(); i != e; ++i) { + NotReady[i]->isPending = false; + // May no longer be available due to backtracking. + if (NotReady[i]->isAvailable) + AvailableQueue.push(NotReady[i]); + } + NotReady.clear(); + + if (CurSU) + ScheduleNodeBottomUp(CurSU, CurCycle); + ++CurCycle; + } + + // Reverse the order since it is bottom up. + std::reverse(Sequence.begin(), Sequence.end()); + +#ifndef NDEBUG + VerifyScheduledSequence(/*isBottomUp=*/true); +#endif +} + + +namespace { +//===----------------------------------------------------------------------===// +// ScheduleDAGLinearize - No scheduling scheduler, it simply linearize the +// DAG in topological order. +// IMPORTANT: this may not work for targets with phyreg dependency. +// +class ScheduleDAGLinearize : public ScheduleDAGSDNodes { +public: + ScheduleDAGLinearize(MachineFunction &mf) : ScheduleDAGSDNodes(mf) {} + + void Schedule() override; + + MachineBasicBlock * + EmitSchedule(MachineBasicBlock::iterator &InsertPos) override; + +private: + std::vector<SDNode*> Sequence; + DenseMap<SDNode*, SDNode*> GluedMap; // Cache glue to its user + + void ScheduleNode(SDNode *N); +}; +} // end anonymous namespace + +void ScheduleDAGLinearize::ScheduleNode(SDNode *N) { + if (N->getNodeId() != 0) + llvm_unreachable(nullptr); + + if (!N->isMachineOpcode() && + (N->getOpcode() == ISD::EntryToken || isPassiveNode(N))) + // These nodes do not need to be translated into MIs. + return; + + LLVM_DEBUG(dbgs() << "\n*** Scheduling: "); + LLVM_DEBUG(N->dump(DAG)); + Sequence.push_back(N); + + unsigned NumOps = N->getNumOperands(); + if (unsigned NumLeft = NumOps) { + SDNode *GluedOpN = nullptr; + do { + const SDValue &Op = N->getOperand(NumLeft-1); + SDNode *OpN = Op.getNode(); + + if (NumLeft == NumOps && Op.getValueType() == MVT::Glue) { + // Schedule glue operand right above N. + GluedOpN = OpN; + assert(OpN->getNodeId() != 0 && "Glue operand not ready?"); + OpN->setNodeId(0); + ScheduleNode(OpN); + continue; + } + + if (OpN == GluedOpN) + // Glue operand is already scheduled. + continue; + + DenseMap<SDNode*, SDNode*>::iterator DI = GluedMap.find(OpN); + if (DI != GluedMap.end() && DI->second != N) + // Users of glues are counted against the glued users. + OpN = DI->second; + + unsigned Degree = OpN->getNodeId(); + assert(Degree > 0 && "Predecessor over-released!"); + OpN->setNodeId(--Degree); + if (Degree == 0) + ScheduleNode(OpN); + } while (--NumLeft); + } +} + +/// findGluedUser - Find the representative use of a glue value by walking +/// the use chain. +static SDNode *findGluedUser(SDNode *N) { + while (SDNode *Glued = N->getGluedUser()) + N = Glued; + return N; +} + +void ScheduleDAGLinearize::Schedule() { + LLVM_DEBUG(dbgs() << "********** DAG Linearization **********\n"); + + SmallVector<SDNode*, 8> Glues; + unsigned DAGSize = 0; + for (SDNode &Node : DAG->allnodes()) { + SDNode *N = &Node; + + // Use node id to record degree. + unsigned Degree = N->use_size(); + N->setNodeId(Degree); + unsigned NumVals = N->getNumValues(); + if (NumVals && N->getValueType(NumVals-1) == MVT::Glue && + N->hasAnyUseOfValue(NumVals-1)) { + SDNode *User = findGluedUser(N); + if (User) { + Glues.push_back(N); + GluedMap.insert(std::make_pair(N, User)); + } + } + + if (N->isMachineOpcode() || + (N->getOpcode() != ISD::EntryToken && !isPassiveNode(N))) + ++DAGSize; + } + + for (unsigned i = 0, e = Glues.size(); i != e; ++i) { + SDNode *Glue = Glues[i]; + SDNode *GUser = GluedMap[Glue]; + unsigned Degree = Glue->getNodeId(); + unsigned UDegree = GUser->getNodeId(); + + // Glue user must be scheduled together with the glue operand. So other + // users of the glue operand must be treated as its users. + SDNode *ImmGUser = Glue->getGluedUser(); + for (const SDNode *U : Glue->uses()) + if (U == ImmGUser) + --Degree; + GUser->setNodeId(UDegree + Degree); + Glue->setNodeId(1); + } + + Sequence.reserve(DAGSize); + ScheduleNode(DAG->getRoot().getNode()); +} + +MachineBasicBlock* +ScheduleDAGLinearize::EmitSchedule(MachineBasicBlock::iterator &InsertPos) { + InstrEmitter Emitter(BB, InsertPos); + DenseMap<SDValue, unsigned> VRBaseMap; + + LLVM_DEBUG({ dbgs() << "\n*** Final schedule ***\n"; }); + + unsigned NumNodes = Sequence.size(); + MachineBasicBlock *BB = Emitter.getBlock(); + for (unsigned i = 0; i != NumNodes; ++i) { + SDNode *N = Sequence[NumNodes-i-1]; + LLVM_DEBUG(N->dump(DAG)); + Emitter.EmitNode(N, false, false, VRBaseMap); + + // Emit any debug values associated with the node. + if (N->getHasDebugValue()) { + MachineBasicBlock::iterator InsertPos = Emitter.getInsertPos(); + for (auto DV : DAG->GetDbgValues(N)) { + if (!DV->isEmitted()) + if (auto *DbgMI = Emitter.EmitDbgValue(DV, VRBaseMap)) + BB->insert(InsertPos, DbgMI); + } + } + } + + LLVM_DEBUG(dbgs() << '\n'); + + InsertPos = Emitter.getInsertPos(); + return Emitter.getBlock(); +} + +//===----------------------------------------------------------------------===// +// Public Constructor Functions +//===----------------------------------------------------------------------===// + +llvm::ScheduleDAGSDNodes * +llvm::createFastDAGScheduler(SelectionDAGISel *IS, CodeGenOpt::Level) { + return new ScheduleDAGFast(*IS->MF); +} + +llvm::ScheduleDAGSDNodes * +llvm::createDAGLinearizer(SelectionDAGISel *IS, CodeGenOpt::Level) { + return new ScheduleDAGLinearize(*IS->MF); +} |