Revert "Resubmit rL345008 "Split MachinePipeliner code into header and cpp files""

This reverts commit r350290.

llvm-svn: 350345

1 files changed, 595 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/MachinePipeliner.cpp b/llvm/lib/CodeGen/MachinePipeliner.cpp
index 845cdc4abc9..de8c55585d3 100644
--- a/llvm/lib/CodeGen/MachinePipeliner.cpp
+++ b/llvm/lib/CodeGen/MachinePipeliner.cpp
@@ -9,6 +9,34 @@
 //
 // An implementation of the Swing Modulo Scheduling (SMS) software pipeliner.
 //
+// Software pipelining (SWP) is an instruction scheduling technique for loops
+// that overlap loop iterations and exploits ILP via a compiler transformation.
+//
+// Swing Modulo Scheduling is an implementation of software pipelining
+// that generates schedules that are near optimal in terms of initiation
+// interval, register requirements, and stage count. See the papers:
+//
+// "Swing Modulo Scheduling: A Lifetime-Sensitive Approach", by J. Llosa,
+// A. Gonzalez, E. Ayguade, and M. Valero. In PACT '96 Proceedings of the 1996
+// Conference on Parallel Architectures and Compilation Techiniques.
+//
+// "Lifetime-Sensitive Modulo Scheduling in a Production Environment", by J.
+// Llosa, E. Ayguade, A. Gonzalez, M. Valero, and J. Eckhardt. In IEEE
+// Transactions on Computers, Vol. 50, No. 3, 2001.
+//
+// "An Implementation of Swing Modulo Scheduling With Extensions for
+// Superblocks", by T. Lattner, Master's Thesis, University of Illinois at
+// Urbana-Chambpain, 2005.
+//
+//
+// The SMS algorithm consists of three main steps after computing the minimal
+// initiation interval (MII).
+// 1) Analyze the dependence graph and compute information about each
+//    instruction in the graph.
+// 2) Order the nodes (instructions) by priority based upon the heuristics
+//    described in the algorithm.
+// 3) Attempt to schedule the nodes in the specified order using the MII.
+//
 // This SMS implementation is a target-independent back-end pass. When enabled,
 // the pass runs just prior to the register allocation pass, while the machine
 // IR is in SSA form. If software pipelining is successful, then the original
@@ -55,11 +83,13 @@
 #include "llvm/CodeGen/MachineLoopInfo.h"
 #include "llvm/CodeGen/MachineMemOperand.h"
 #include "llvm/CodeGen/MachineOperand.h"
-#include "llvm/CodeGen/MachinePipeliner.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/RegisterClassInfo.h"
 #include "llvm/CodeGen/RegisterPressure.h"
 #include "llvm/CodeGen/ScheduleDAG.h"
+#include "llvm/CodeGen/ScheduleDAGInstrs.h"
 #include "llvm/CodeGen/ScheduleDAGMutation.h"
+#include "llvm/CodeGen/TargetInstrInfo.h"
 #include "llvm/CodeGen/TargetOpcodes.h"
 #include "llvm/CodeGen/TargetRegisterInfo.h"
 #include "llvm/CodeGen/TargetSubtargetInfo.h"
@@ -141,15 +171,575 @@ static cl::opt<bool> SwpIgnoreRecMII("pipeliner-ignore-recmii",
                                      cl::ReallyHidden, cl::init(false),
                                      cl::ZeroOrMore, cl::desc("Ignore RecMII"));
 
-namespace llvm {
-
 // A command line option to enable the CopyToPhi DAG mutation.
-cl::opt<bool>
+static cl::opt<bool>
     SwpEnableCopyToPhi("pipeliner-enable-copytophi", cl::ReallyHidden,
                        cl::init(true), cl::ZeroOrMore,
                        cl::desc("Enable CopyToPhi DAG Mutation"));
 
-} // end namespace llvm
+namespace {
+
+class NodeSet;
+class SMSchedule;
+
+/// The main class in the implementation of the target independent
+/// software pipeliner pass.
+class MachinePipeliner : public MachineFunctionPass {
+public:
+  MachineFunction *MF = nullptr;
+  const MachineLoopInfo *MLI = nullptr;
+  const MachineDominatorTree *MDT = nullptr;
+  const InstrItineraryData *InstrItins;
+  const TargetInstrInfo *TII = nullptr;
+  RegisterClassInfo RegClassInfo;
+
+#ifndef NDEBUG
+  static int NumTries;
+#endif
+
+  /// Cache the target analysis information about the loop.
+  struct LoopInfo {
+    MachineBasicBlock *TBB = nullptr;
+    MachineBasicBlock *FBB = nullptr;
+    SmallVector<MachineOperand, 4> BrCond;
+    MachineInstr *LoopInductionVar = nullptr;
+    MachineInstr *LoopCompare = nullptr;
+  };
+  LoopInfo LI;
+
+  static char ID;
+
+  MachinePipeliner() : MachineFunctionPass(ID) {
+    initializeMachinePipelinerPass(*PassRegistry::getPassRegistry());
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequired<AAResultsWrapperPass>();
+    AU.addPreserved<AAResultsWrapperPass>();
+    AU.addRequired<MachineLoopInfo>();
+    AU.addRequired<MachineDominatorTree>();
+    AU.addRequired<LiveIntervals>();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+
+private:
+  void preprocessPhiNodes(MachineBasicBlock &B);
+  bool canPipelineLoop(MachineLoop &L);
+  bool scheduleLoop(MachineLoop &L);
+  bool swingModuloScheduler(MachineLoop &L);
+};
+
+/// This class builds the dependence graph for the instructions in a loop,
+/// and attempts to schedule the instructions using the SMS algorithm.
+class SwingSchedulerDAG : public ScheduleDAGInstrs {
+  MachinePipeliner &Pass;
+  /// The minimum initiation interval between iterations for this schedule.
+  unsigned MII = 0;
+  /// Set to true if a valid pipelined schedule is found for the loop.
+  bool Scheduled = false;
+  MachineLoop &Loop;
+  LiveIntervals &LIS;
+  const RegisterClassInfo &RegClassInfo;
+
+  /// A toplogical ordering of the SUnits, which is needed for changing
+  /// dependences and iterating over the SUnits.
+  ScheduleDAGTopologicalSort Topo;
+
+  struct NodeInfo {
+    int ASAP = 0;
+    int ALAP = 0;
+    int ZeroLatencyDepth = 0;
+    int ZeroLatencyHeight = 0;
+
+    NodeInfo() = default;
+  };
+  /// Computed properties for each node in the graph.
+  std::vector<NodeInfo> ScheduleInfo;
+
+  enum OrderKind { BottomUp = 0, TopDown = 1 };
+  /// Computed node ordering for scheduling.
+  SetVector<SUnit *> NodeOrder;
+
+  using NodeSetType = SmallVector<NodeSet, 8>;
+  using ValueMapTy = DenseMap<unsigned, unsigned>;
+  using MBBVectorTy = SmallVectorImpl<MachineBasicBlock *>;
+  using InstrMapTy = DenseMap<MachineInstr *, MachineInstr *>;
+
+  /// Instructions to change when emitting the final schedule.
+  DenseMap<SUnit *, std::pair<unsigned, int64_t>> InstrChanges;
+
+  /// We may create a new instruction, so remember it because it
+  /// must be deleted when the pass is finished.
+  SmallPtrSet<MachineInstr *, 4> NewMIs;
+
+  /// Ordered list of DAG postprocessing steps.
+  std::vector<std::unique_ptr<ScheduleDAGMutation>> Mutations;
+
+  /// Helper class to implement Johnson's circuit finding algorithm.
+  class Circuits {
+    std::vector<SUnit> &SUnits;
+    SetVector<SUnit *> Stack;
+    BitVector Blocked;
+    SmallVector<SmallPtrSet<SUnit *, 4>, 10> B;
+    SmallVector<SmallVector<int, 4>, 16> AdjK;
+    // Node to Index from ScheduleDAGTopologicalSort
+    std::vector<int> *Node2Idx;
+    unsigned NumPaths;
+    static unsigned MaxPaths;
+
+  public:
+    Circuits(std::vector<SUnit> &SUs, ScheduleDAGTopologicalSort &Topo)
+        : SUnits(SUs), Blocked(SUs.size()), B(SUs.size()), AdjK(SUs.size()) {
+      Node2Idx = new std::vector<int>(SUs.size());
+      unsigned Idx = 0;
+      for (const auto &NodeNum : Topo)
+        Node2Idx->at(NodeNum) = Idx++;
+    }
+
+    ~Circuits() { delete Node2Idx; }
+
+    /// Reset the data structures used in the circuit algorithm.
+    void reset() {
+      Stack.clear();
+      Blocked.reset();
+      B.assign(SUnits.size(), SmallPtrSet<SUnit *, 4>());
+      NumPaths = 0;
+    }
+
+    void createAdjacencyStructure(SwingSchedulerDAG *DAG);
+    bool circuit(int V, int S, NodeSetType &NodeSets, bool HasBackedge = false);
+    void unblock(int U);
+  };
+
+  struct CopyToPhiMutation : public ScheduleDAGMutation {
+    void apply(ScheduleDAGInstrs *DAG) override;
+  };
+
+public:
+  SwingSchedulerDAG(MachinePipeliner &P, MachineLoop &L, LiveIntervals &lis,
+                    const RegisterClassInfo &rci)
+      : ScheduleDAGInstrs(*P.MF, P.MLI, false), Pass(P), Loop(L), LIS(lis),
+        RegClassInfo(rci), Topo(SUnits, &ExitSU) {
+    P.MF->getSubtarget().getSMSMutations(Mutations);
+    if (SwpEnableCopyToPhi)
+      Mutations.push_back(llvm::make_unique<CopyToPhiMutation>());
+  }
+
+  void schedule() override;
+  void finishBlock() override;
+
+  /// Return true if the loop kernel has been scheduled.
+  bool hasNewSchedule() { return Scheduled; }
+
+  /// Return the earliest time an instruction may be scheduled.
+  int getASAP(SUnit *Node) { return ScheduleInfo[Node->NodeNum].ASAP; }
+
+  /// Return the latest time an instruction my be scheduled.
+  int getALAP(SUnit *Node) { return ScheduleInfo[Node->NodeNum].ALAP; }
+
+  /// The mobility function, which the number of slots in which
+  /// an instruction may be scheduled.
+  int getMOV(SUnit *Node) { return getALAP(Node) - getASAP(Node); }
+
+  /// The depth, in the dependence graph, for a node.
+  unsigned getDepth(SUnit *Node) { return Node->getDepth(); }
+
+  /// The maximum unweighted length of a path from an arbitrary node to the
+  /// given node in which each edge has latency 0
+  int getZeroLatencyDepth(SUnit *Node) {
+    return ScheduleInfo[Node->NodeNum].ZeroLatencyDepth;
+  }
+
+  /// The height, in the dependence graph, for a node.
+  unsigned getHeight(SUnit *Node) { return Node->getHeight(); }
+
+  /// The maximum unweighted length of a path from the given node to an
+  /// arbitrary node in which each edge has latency 0
+  int getZeroLatencyHeight(SUnit *Node) {
+    return ScheduleInfo[Node->NodeNum].ZeroLatencyHeight;
+  }
+
+  /// Return true if the dependence is a back-edge in the data dependence graph.
+  /// Since the DAG doesn't contain cycles, we represent a cycle in the graph
+  /// using an anti dependence from a Phi to an instruction.
+  bool isBackedge(SUnit *Source, const SDep &Dep) {
+    if (Dep.getKind() != SDep::Anti)
+      return false;
+    return Source->getInstr()->isPHI() || Dep.getSUnit()->getInstr()->isPHI();
+  }
+
+  bool isLoopCarriedDep(SUnit *Source, const SDep &Dep, bool isSucc = true);
+
+  /// The distance function, which indicates that operation V of iteration I
+  /// depends on operations U of iteration I-distance.
+  unsigned getDistance(SUnit *U, SUnit *V, const SDep &Dep) {
+    // Instructions that feed a Phi have a distance of 1. Computing larger
+    // values for arrays requires data dependence information.
+    if (V->getInstr()->isPHI() && Dep.getKind() == SDep::Anti)
+      return 1;
+    return 0;
+  }
+
+  /// Set the Minimum Initiation Interval for this schedule attempt.
+  void setMII(unsigned mii) { MII = mii; }
+
+  void applyInstrChange(MachineInstr *MI, SMSchedule &Schedule);
+
+  void fixupRegisterOverlaps(std::deque<SUnit *> &Instrs);
+
+  /// Return the new base register that was stored away for the changed
+  /// instruction.
+  unsigned getInstrBaseReg(SUnit *SU) {
+    DenseMap<SUnit *, std::pair<unsigned, int64_t>>::iterator It =
+        InstrChanges.find(SU);
+    if (It != InstrChanges.end())
+      return It->second.first;
+    return 0;
+  }
+
+  void addMutation(std::unique_ptr<ScheduleDAGMutation> Mutation) {
+    Mutations.push_back(std::move(Mutation));
+  }
+
+  static bool classof(const ScheduleDAGInstrs *DAG) { return true; }
+
+private:
+  void addLoopCarriedDependences(AliasAnalysis *AA);
+  void updatePhiDependences();
+  void changeDependences();
+  unsigned calculateResMII();
+  unsigned calculateRecMII(NodeSetType &RecNodeSets);
+  void findCircuits(NodeSetType &NodeSets);
+  void fuseRecs(NodeSetType &NodeSets);
+  void removeDuplicateNodes(NodeSetType &NodeSets);
+  void computeNodeFunctions(NodeSetType &NodeSets);
+  void registerPressureFilter(NodeSetType &NodeSets);
+  void colocateNodeSets(NodeSetType &NodeSets);
+  void checkNodeSets(NodeSetType &NodeSets);
+  void groupRemainingNodes(NodeSetType &NodeSets);
+  void addConnectedNodes(SUnit *SU, NodeSet &NewSet,
+                         SetVector<SUnit *> &NodesAdded);
+  void computeNodeOrder(NodeSetType &NodeSets);
+  void checkValidNodeOrder(const NodeSetType &Circuits) const;
+  bool schedulePipeline(SMSchedule &Schedule);
+  void generatePipelinedLoop(SMSchedule &Schedule);
+  void generateProlog(SMSchedule &Schedule, unsigned LastStage,
+                      MachineBasicBlock *KernelBB, ValueMapTy *VRMap,
+                      MBBVectorTy &PrologBBs);
+  void generateEpilog(SMSchedule &Schedule, unsigned LastStage,
+                      MachineBasicBlock *KernelBB, ValueMapTy *VRMap,
+                      MBBVectorTy &EpilogBBs, MBBVectorTy &PrologBBs);
+  void generateExistingPhis(MachineBasicBlock *NewBB, MachineBasicBlock *BB1,
+                            MachineBasicBlock *BB2, MachineBasicBlock *KernelBB,
+                            SMSchedule &Schedule, ValueMapTy *VRMap,
+                            InstrMapTy &InstrMap, unsigned LastStageNum,
+                            unsigned CurStageNum, bool IsLast);
+  void generatePhis(MachineBasicBlock *NewBB, MachineBasicBlock *BB1,
+                    MachineBasicBlock *BB2, MachineBasicBlock *KernelBB,
+                    SMSchedule &Schedule, ValueMapTy *VRMap,
+                    InstrMapTy &InstrMap, unsigned LastStageNum,
+                    unsigned CurStageNum, bool IsLast);
+  void removeDeadInstructions(MachineBasicBlock *KernelBB,
+                              MBBVectorTy &EpilogBBs);
+  void splitLifetimes(MachineBasicBlock *KernelBB, MBBVectorTy &EpilogBBs,
+                      SMSchedule &Schedule);
+  void addBranches(MBBVectorTy &PrologBBs, MachineBasicBlock *KernelBB,
+                   MBBVectorTy &EpilogBBs, SMSchedule &Schedule,
+                   ValueMapTy *VRMap);
+  bool computeDelta(MachineInstr &MI, unsigned &Delta);
+  void updateMemOperands(MachineInstr &NewMI, MachineInstr &OldMI,
+                         unsigned Num);
+  MachineInstr *cloneInstr(MachineInstr *OldMI, unsigned CurStageNum,
+                           unsigned InstStageNum);
+  MachineInstr *cloneAndChangeInstr(MachineInstr *OldMI, unsigned CurStageNum,
+                                    unsigned InstStageNum,
+                                    SMSchedule &Schedule);
+  void updateInstruction(MachineInstr *NewMI, bool LastDef,
+                         unsigned CurStageNum, unsigned InstrStageNum,
+                         SMSchedule &Schedule, ValueMapTy *VRMap);
+  MachineInstr *findDefInLoop(unsigned Reg);
+  unsigned getPrevMapVal(unsigned StageNum, unsigned PhiStage, unsigned LoopVal,
+                         unsigned LoopStage, ValueMapTy *VRMap,
+                         MachineBasicBlock *BB);
+  void rewritePhiValues(MachineBasicBlock *NewBB, unsigned StageNum,
+                        SMSchedule &Schedule, ValueMapTy *VRMap,
+                        InstrMapTy &InstrMap);
+  void rewriteScheduledInstr(MachineBasicBlock *BB, SMSchedule &Schedule,
+                             InstrMapTy &InstrMap, unsigned CurStageNum,
+                             unsigned PhiNum, MachineInstr *Phi,
+                             unsigned OldReg, unsigned NewReg,
+                             unsigned PrevReg = 0);
+  bool canUseLastOffsetValue(MachineInstr *MI, unsigned &BasePos,
+                             unsigned &OffsetPos, unsigned &NewBase,
+                             int64_t &NewOffset);
+  void postprocessDAG();
+};
+
+/// A NodeSet contains a set of SUnit DAG nodes with additional information
+/// that assigns a priority to the set.
+class NodeSet {
+  SetVector<SUnit *> Nodes;
+  bool HasRecurrence = false;
+  unsigned RecMII = 0;
+  int MaxMOV = 0;
+  unsigned MaxDepth = 0;
+  unsigned Colocate = 0;
+  SUnit *ExceedPressure = nullptr;
+  unsigned Latency = 0;
+
+public:
+  using iterator = SetVector<SUnit *>::const_iterator;
+
+  NodeSet() = default;
+  NodeSet(iterator S, iterator E) : Nodes(S, E), HasRecurrence(true) {
+    Latency = 0;
+    for (unsigned i = 0, e = Nodes.size(); i < e; ++i)
+      for (const SDep &Succ : Nodes[i]->Succs)
+        if (Nodes.count(Succ.getSUnit()))
+          Latency += Succ.getLatency();
+  }
+
+  bool insert(SUnit *SU) { return Nodes.insert(SU); }
+
+  void insert(iterator S, iterator E) { Nodes.insert(S, E); }
+
+  template <typename UnaryPredicate> bool remove_if(UnaryPredicate P) {
+    return Nodes.remove_if(P);
+  }
+
+  unsigned count(SUnit *SU) const { return Nodes.count(SU); }
+
+  bool hasRecurrence() { return HasRecurrence; };
+
+  unsigned size() const { return Nodes.size(); }
+
+  bool empty() const { return Nodes.empty(); }
+
+  SUnit *getNode(unsigned i) const { return Nodes[i]; };
+
+  void setRecMII(unsigned mii) { RecMII = mii; };
+
+  void setColocate(unsigned c) { Colocate = c; };
+
+  void setExceedPressure(SUnit *SU) { ExceedPressure = SU; }
+
+  bool isExceedSU(SUnit *SU) { return ExceedPressure == SU; }
+
+  int compareRecMII(NodeSet &RHS) { return RecMII - RHS.RecMII; }
+
+  int getRecMII() { return RecMII; }
+
+  /// Summarize node functions for the entire node set.
+  void computeNodeSetInfo(SwingSchedulerDAG *SSD) {
+    for (SUnit *SU : *this) {
+      MaxMOV = std::max(MaxMOV, SSD->getMOV(SU));
+      MaxDepth = std::max(MaxDepth, SSD->getDepth(SU));
+    }
+  }
+
+  unsigned getLatency() { return Latency; }
+
+  unsigned getMaxDepth() { return MaxDepth; }
+
+  void clear() {
+    Nodes.clear();
+    RecMII = 0;
+    HasRecurrence = false;
+    MaxMOV = 0;
+    MaxDepth = 0;
+    Colocate = 0;
+    ExceedPressure = nullptr;
+  }
+
+  operator SetVector<SUnit *> &() { return Nodes; }
+
+  /// Sort the node sets by importance. First, rank them by recurrence MII,
+  /// then by mobility (least mobile done first), and finally by depth.
+  /// Each node set may contain a colocate value which is used as the first
+  /// tie breaker, if it's set.
+  bool operator>(const NodeSet &RHS) const {
+    if (RecMII == RHS.RecMII) {
+      if (Colocate != 0 && RHS.Colocate != 0 && Colocate != RHS.Colocate)
+        return Colocate < RHS.Colocate;
+      if (MaxMOV == RHS.MaxMOV)
+        return MaxDepth > RHS.MaxDepth;
+      return MaxMOV < RHS.MaxMOV;
+    }
+    return RecMII > RHS.RecMII;
+  }
+
+  bool operator==(const NodeSet &RHS) const {
+    return RecMII == RHS.RecMII && MaxMOV == RHS.MaxMOV &&
+           MaxDepth == RHS.MaxDepth;
+  }
+
+  bool operator!=(const NodeSet &RHS) const { return !operator==(RHS); }
+
+  iterator begin() { return Nodes.begin(); }
+  iterator end() { return Nodes.end(); }
+
+  void print(raw_ostream &os) const {
+    os << "Num nodes " << size() << " rec " << RecMII << " mov " << MaxMOV
+       << " depth " << MaxDepth << " col " << Colocate << "\n";
+    for (const auto &I : Nodes)
+      os << "   SU(" << I->NodeNum << ") " << *(I->getInstr());
+    os << "\n";
+  }
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+  LLVM_DUMP_METHOD void dump() const { print(dbgs()); }
+#endif
+};
+
+/// This class represents the scheduled code.  The main data structure is a
+/// map from scheduled cycle to instructions.  During scheduling, the
+/// data structure explicitly represents all stages/iterations.   When
+/// the algorithm finshes, the schedule is collapsed into a single stage,
+/// which represents instructions from different loop iterations.
+///
+/// The SMS algorithm allows negative values for cycles, so the first cycle
+/// in the schedule is the smallest cycle value.
+class SMSchedule {
+private:
+  /// Map from execution cycle to instructions.
+  DenseMap<int, std::deque<SUnit *>> ScheduledInstrs;
+
+  /// Map from instruction to execution cycle.
+  std::map<SUnit *, int> InstrToCycle;
+
+  /// Map for each register and the max difference between its uses and def.
+  /// The first element in the pair is the max difference in stages. The
+  /// second is true if the register defines a Phi value and loop value is
+  /// scheduled before the Phi.
+  std::map<unsigned, std::pair<unsigned, bool>> RegToStageDiff;
+
+  /// Keep track of the first cycle value in the schedule.  It starts
+  /// as zero, but the algorithm allows negative values.
+  int FirstCycle = 0;
+
+  /// Keep track of the last cycle value in the schedule.
+  int LastCycle = 0;
+
+  /// The initiation interval (II) for the schedule.
+  int InitiationInterval = 0;
+
+  /// Target machine information.
+  const TargetSubtargetInfo &ST;
+
+  /// Virtual register information.
+  MachineRegisterInfo &MRI;
+
+  std::unique_ptr<DFAPacketizer> Resources;
+
+public:
+  SMSchedule(MachineFunction *mf)
+      : ST(mf->getSubtarget()), MRI(mf->getRegInfo()),
+        Resources(ST.getInstrInfo()->CreateTargetScheduleState(ST)) {}
+
+  void reset() {
+    ScheduledInstrs.clear();
+    InstrToCycle.clear();
+    RegToStageDiff.clear();
+    FirstCycle = 0;
+    LastCycle = 0;
+    InitiationInterval = 0;
+  }
+
+  /// Set the initiation interval for this schedule.
+  void setInitiationInterval(int ii) { InitiationInterval = ii; }
+
+  /// Return the first cycle in the completed schedule.  This
+  /// can be a negative value.
+  int getFirstCycle() const { return FirstCycle; }
+
+  /// Return the last cycle in the finalized schedule.
+  int getFinalCycle() const { return FirstCycle + InitiationInterval - 1; }
+
+  /// Return the cycle of the earliest scheduled instruction in the dependence
+  /// chain.
+  int earliestCycleInChain(const SDep &Dep);
+
+  /// Return the cycle of the latest scheduled instruction in the dependence
+  /// chain.
+  int latestCycleInChain(const SDep &Dep);
+
+  void computeStart(SUnit *SU, int *MaxEarlyStart, int *MinLateStart,
+                    int *MinEnd, int *MaxStart, int II, SwingSchedulerDAG *DAG);
+  bool insert(SUnit *SU, int StartCycle, int EndCycle, int II);
+
+  /// Iterators for the cycle to instruction map.
+  using sched_iterator = DenseMap<int, std::deque<SUnit *>>::iterator;
+  using const_sched_iterator =
+      DenseMap<int, std::deque<SUnit *>>::const_iterator;
+
+  /// Return true if the instruction is scheduled at the specified stage.
+  bool isScheduledAtStage(SUnit *SU, unsigned StageNum) {
+    return (stageScheduled(SU) == (int)StageNum);
+  }
+
+  /// Return the stage for a scheduled instruction.  Return -1 if
+  /// the instruction has not been scheduled.
+  int stageScheduled(SUnit *SU) const {
+    std::map<SUnit *, int>::const_iterator it = InstrToCycle.find(SU);
+    if (it == InstrToCycle.end())
+      return -1;
+    return (it->second - FirstCycle) / InitiationInterval;
+  }
+
+  /// Return the cycle for a scheduled instruction. This function normalizes
+  /// the first cycle to be 0.
+  unsigned cycleScheduled(SUnit *SU) const {
+    std::map<SUnit *, int>::const_iterator it = InstrToCycle.find(SU);
+    assert(it != InstrToCycle.end() && "Instruction hasn't been scheduled.");
+    return (it->second - FirstCycle) % InitiationInterval;
+  }
+
+  /// Return the maximum stage count needed for this schedule.
+  unsigned getMaxStageCount() {
+    return (LastCycle - FirstCycle) / InitiationInterval;
+  }
+
+  /// Return the max. number of stages/iterations that can occur between a
+  /// register definition and its uses.
+  unsigned getStagesForReg(int Reg, unsigned CurStage) {
+    std::pair<unsigned, bool> Stages = RegToStageDiff[Reg];
+    if (CurStage > getMaxStageCount() && Stages.first == 0 && Stages.second)
+      return 1;
+    return Stages.first;
+  }
+
+  /// The number of stages for a Phi is a little different than other
+  /// instructions. The minimum value computed in RegToStageDiff is 1
+  /// because we assume the Phi is needed for at least 1 iteration.
+  /// This is not the case if the loop value is scheduled prior to the
+  /// Phi in the same stage.  This function returns the number of stages
+  /// or iterations needed between the Phi definition and any uses.
+  unsigned getStagesForPhi(int Reg) {
+    std::pair<unsigned, bool> Stages = RegToStageDiff[Reg];
+    if (Stages.second)
+      return Stages.first;
+    return Stages.first - 1;
+  }
+
+  /// Return the instructions that are scheduled at the specified cycle.
+  std::deque<SUnit *> &getInstructions(int cycle) {
+    return ScheduledInstrs[cycle];
+  }
+
+  bool isValidSchedule(SwingSchedulerDAG *SSD);
+  void finalizeSchedule(SwingSchedulerDAG *SSD);
+  void orderDependence(SwingSchedulerDAG *SSD, SUnit *SU,
+                       std::deque<SUnit *> &Insts);
+  bool isLoopCarried(SwingSchedulerDAG *SSD, MachineInstr &Phi);
+  bool isLoopCarriedDefOfUse(SwingSchedulerDAG *SSD, MachineInstr *Def,
+                             MachineOperand &MO);
+  void print(raw_ostream &os) const;
+  void dump() const;
+};
+
+} // end anonymous namespace
 
 unsigned SwingSchedulerDAG::Circuits::MaxPaths = 5;
 char MachinePipeliner::ID = 0;