--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp	Thu Dec 12 13:56:28 2013 +0900
@@ -0,0 +1,3040 @@
+//===----- ScheduleDAGRRList.cpp - Reg pressure reduction 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 bottom-up and top-down register pressure reduction list
+// schedulers, using standard algorithms.  The basic approach uses a priority
+// queue of available nodes to schedule.  One at a time, nodes are taken from
+// the priority queue (thus in priority order), checked for legality to
+// schedule, and emitted if legal.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "pre-RA-sched"
+#include "llvm/CodeGen/SchedulerRegistry.h"
+#include "ScheduleDAGSDNodes.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
+#include "llvm/CodeGen/SelectionDAGISel.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"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include <climits>
+using namespace llvm;
+
+STATISTIC(NumBacktracks, "Number of times scheduler backtracked");
+STATISTIC(NumUnfolds,    "Number of nodes unfolded");
+STATISTIC(NumDups,       "Number of duplicated nodes");
+STATISTIC(NumPRCopies,   "Number of physical register copies");
+
+static RegisterScheduler
+  burrListDAGScheduler("list-burr",
+                       "Bottom-up register reduction list scheduling",
+                       createBURRListDAGScheduler);
+static RegisterScheduler
+  sourceListDAGScheduler("source",
+                         "Similar to list-burr but schedules in source "
+                         "order when possible",
+                         createSourceListDAGScheduler);
+
+static RegisterScheduler
+  hybridListDAGScheduler("list-hybrid",
+                         "Bottom-up register pressure aware list scheduling "
+                         "which tries to balance latency and register pressure",
+                         createHybridListDAGScheduler);
+
+static RegisterScheduler
+  ILPListDAGScheduler("list-ilp",
+                      "Bottom-up register pressure aware list scheduling "
+                      "which tries to balance ILP and register pressure",
+                      createILPListDAGScheduler);
+
+static cl::opt<bool> DisableSchedCycles(
+  "disable-sched-cycles", cl::Hidden, cl::init(false),
+  cl::desc("Disable cycle-level precision during preRA scheduling"));
+
+// Temporary sched=list-ilp flags until the heuristics are robust.
+// Some options are also available under sched=list-hybrid.
+static cl::opt<bool> DisableSchedRegPressure(
+  "disable-sched-reg-pressure", cl::Hidden, cl::init(false),
+  cl::desc("Disable regpressure priority in sched=list-ilp"));
+static cl::opt<bool> DisableSchedLiveUses(
+  "disable-sched-live-uses", cl::Hidden, cl::init(true),
+  cl::desc("Disable live use priority in sched=list-ilp"));
+static cl::opt<bool> DisableSchedVRegCycle(
+  "disable-sched-vrcycle", cl::Hidden, cl::init(false),
+  cl::desc("Disable virtual register cycle interference checks"));
+static cl::opt<bool> DisableSchedPhysRegJoin(
+  "disable-sched-physreg-join", cl::Hidden, cl::init(false),
+  cl::desc("Disable physreg def-use affinity"));
+static cl::opt<bool> DisableSchedStalls(
+  "disable-sched-stalls", cl::Hidden, cl::init(true),
+  cl::desc("Disable no-stall priority in sched=list-ilp"));
+static cl::opt<bool> DisableSchedCriticalPath(
+  "disable-sched-critical-path", cl::Hidden, cl::init(false),
+  cl::desc("Disable critical path priority in sched=list-ilp"));
+static cl::opt<bool> DisableSchedHeight(
+  "disable-sched-height", cl::Hidden, cl::init(false),
+  cl::desc("Disable scheduled-height priority in sched=list-ilp"));
+static cl::opt<bool> Disable2AddrHack(
+  "disable-2addr-hack", cl::Hidden, cl::init(true),
+  cl::desc("Disable scheduler's two-address hack"));
+
+static cl::opt<int> MaxReorderWindow(
+  "max-sched-reorder", cl::Hidden, cl::init(6),
+  cl::desc("Number of instructions to allow ahead of the critical path "
+           "in sched=list-ilp"));
+
+static cl::opt<unsigned> AvgIPC(
+  "sched-avg-ipc", cl::Hidden, cl::init(1),
+  cl::desc("Average inst/cycle whan no target itinerary exists."));
+
+namespace {
+//===----------------------------------------------------------------------===//
+/// ScheduleDAGRRList - The actual register reduction list scheduler
+/// implementation.  This supports both top-down and bottom-up scheduling.
+///
+class ScheduleDAGRRList : public ScheduleDAGSDNodes {
+private:
+  /// NeedLatency - True if the scheduler will make use of latency information.
+  ///
+  bool NeedLatency;
+
+  /// AvailableQueue - The priority queue to use for the available SUnits.
+  SchedulingPriorityQueue *AvailableQueue;
+
+  /// PendingQueue - This contains all of the instructions whose operands have
+  /// been issued, but their results are not ready yet (due to the latency of
+  /// the operation).  Once the operands becomes available, the instruction is
+  /// added to the AvailableQueue.
+  std::vector<SUnit*> PendingQueue;
+
+  /// HazardRec - The hazard recognizer to use.
+  ScheduleHazardRecognizer *HazardRec;
+
+  /// CurCycle - The current scheduler state corresponds to this cycle.
+  unsigned CurCycle;
+
+  /// MinAvailableCycle - Cycle of the soonest available instruction.
+  unsigned MinAvailableCycle;
+
+  /// IssueCount - Count instructions issued in this cycle
+  /// Currently valid only for bottom-up scheduling.
+  unsigned IssueCount;
+
+  /// 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<SUnit*> LiveRegGens;
+
+  // Collect interferences between physical register use/defs.
+  // Each interference is an SUnit and set of physical registers.
+  SmallVector<SUnit*, 4> Interferences;
+  typedef DenseMap<SUnit*, SmallVector<unsigned, 4> > LRegsMapT;
+  LRegsMapT LRegsMap;
+
+  /// Topo - A topological ordering for SUnits which permits fast IsReachable
+  /// and similar queries.
+  ScheduleDAGTopologicalSort Topo;
+
+  // Hack to keep track of the inverse of FindCallSeqStart without more crazy
+  // DAG crawling.
+  DenseMap<SUnit*, SUnit*> CallSeqEndForStart;
+
+public:
+  ScheduleDAGRRList(MachineFunction &mf, bool needlatency,
+                    SchedulingPriorityQueue *availqueue,
+                    CodeGenOpt::Level OptLevel)
+    : ScheduleDAGSDNodes(mf),
+      NeedLatency(needlatency), AvailableQueue(availqueue), CurCycle(0),
+      Topo(SUnits, NULL) {
+
+    const TargetMachine &tm = mf.getTarget();
+    if (DisableSchedCycles || !NeedLatency)
+      HazardRec = new ScheduleHazardRecognizer();
+    else
+      HazardRec = tm.getInstrInfo()->CreateTargetHazardRecognizer(&tm, this);
+  }
+
+  ~ScheduleDAGRRList() {
+    delete HazardRec;
+    delete AvailableQueue;
+  }
+
+  void Schedule();
+
+  ScheduleHazardRecognizer *getHazardRec() { return HazardRec; }
+
+  /// IsReachable - Checks if SU is reachable from TargetSU.
+  bool IsReachable(const SUnit *SU, const SUnit *TargetSU) {
+    return Topo.IsReachable(SU, TargetSU);
+  }
+
+  /// WillCreateCycle - Returns true if adding an edge from SU to TargetSU will
+  /// create a cycle.
+  bool WillCreateCycle(SUnit *SU, SUnit *TargetSU) {
+    return Topo.WillCreateCycle(SU, TargetSU);
+  }
+
+  /// AddPred - adds a predecessor edge to SUnit SU.
+  /// This returns true if this is a new predecessor.
+  /// Updates the topological ordering if required.
+  void AddPred(SUnit *SU, const SDep &D) {
+    Topo.AddPred(SU, D.getSUnit());
+    SU->addPred(D);
+  }
+
+  /// RemovePred - removes a predecessor edge from SUnit SU.
+  /// This returns true if an edge was removed.
+  /// Updates the topological ordering if required.
+  void RemovePred(SUnit *SU, const SDep &D) {
+    Topo.RemovePred(SU, D.getSUnit());
+    SU->removePred(D);
+  }
+
+private:
+  bool isReady(SUnit *SU) {
+    return DisableSchedCycles || !AvailableQueue->hasReadyFilter() ||
+      AvailableQueue->isReady(SU);
+  }
+
+  void ReleasePred(SUnit *SU, const SDep *PredEdge);
+  void ReleasePredecessors(SUnit *SU);
+  void ReleasePending();
+  void AdvanceToCycle(unsigned NextCycle);
+  void AdvancePastStalls(SUnit *SU);
+  void EmitNode(SUnit *SU);
+  void ScheduleNodeBottomUp(SUnit*);
+  void CapturePred(SDep *PredEdge);
+  void UnscheduleNodeBottomUp(SUnit*);
+  void RestoreHazardCheckerBottomUp();
+  void BacktrackBottomUp(SUnit*, SUnit*);
+  SUnit *CopyAndMoveSuccessors(SUnit*);
+  void InsertCopiesAndMoveSuccs(SUnit*, unsigned,
+                                const TargetRegisterClass*,
+                                const TargetRegisterClass*,
+                                SmallVectorImpl<SUnit*>&);
+  bool DelayForLiveRegsBottomUp(SUnit*, SmallVectorImpl<unsigned>&);
+
+  void releaseInterferences(unsigned Reg = 0);
+
+  SUnit *PickNodeToScheduleBottomUp();
+  void ListScheduleBottomUp();
+
+  /// CreateNewSUnit - Creates a new SUnit and returns a pointer to it.
+  /// Updates the topological ordering if required.
+  SUnit *CreateNewSUnit(SDNode *N) {
+    unsigned NumSUnits = SUnits.size();
+    SUnit *NewNode = newSUnit(N);
+    // Update the topological ordering.
+    if (NewNode->NodeNum >= NumSUnits)
+      Topo.InitDAGTopologicalSorting();
+    return NewNode;
+  }
+
+  /// CreateClone - Creates a new SUnit from an existing one.
+  /// Updates the topological ordering if required.
+  SUnit *CreateClone(SUnit *N) {
+    unsigned NumSUnits = SUnits.size();
+    SUnit *NewNode = Clone(N);
+    // Update the topological ordering.
+    if (NewNode->NodeNum >= NumSUnits)
+      Topo.InitDAGTopologicalSorting();
+    return NewNode;
+  }
+
+  /// forceUnitLatencies - Register-pressure-reducing scheduling doesn't
+  /// need actual latency information but the hybrid scheduler does.
+  bool forceUnitLatencies() const {
+    return !NeedLatency;
+  }
+};
+}  // end anonymous namespace
+
+/// GetCostForDef - Looks up the register class and cost for a given definition.
+/// Typically this just means looking up the representative register class,
+/// but for untyped values (MVT::Untyped) it means inspecting the node's
+/// opcode to determine what register class is being generated.
+static void GetCostForDef(const ScheduleDAGSDNodes::RegDefIter &RegDefPos,
+                          const TargetLowering *TLI,
+                          const TargetInstrInfo *TII,
+                          const TargetRegisterInfo *TRI,
+                          unsigned &RegClass, unsigned &Cost,
+                          const MachineFunction &MF) {
+  MVT VT = RegDefPos.GetValue();
+
+  // Special handling for untyped values.  These values can only come from
+  // the expansion of custom DAG-to-DAG patterns.
+  if (VT == MVT::Untyped) {
+    const SDNode *Node = RegDefPos.GetNode();
+
+    // Special handling for CopyFromReg of untyped values.
+    if (!Node->isMachineOpcode() && Node->getOpcode() == ISD::CopyFromReg) {
+      unsigned Reg = cast<RegisterSDNode>(Node->getOperand(1))->getReg();
+      const TargetRegisterClass *RC = MF.getRegInfo().getRegClass(Reg);
+      RegClass = RC->getID();
+      Cost = 1;
+      return;
+    }
+
+    unsigned Opcode = Node->getMachineOpcode();
+    if (Opcode == TargetOpcode::REG_SEQUENCE) {
+      unsigned DstRCIdx = cast<ConstantSDNode>(Node->getOperand(0))->getZExtValue();
+      const TargetRegisterClass *RC = TRI->getRegClass(DstRCIdx);
+      RegClass = RC->getID();
+      Cost = 1;
+      return;
+    }
+
+    unsigned Idx = RegDefPos.GetIdx();
+    const MCInstrDesc Desc = TII->get(Opcode);
+    const TargetRegisterClass *RC = TII->getRegClass(Desc, Idx, TRI, MF);
+    RegClass = RC->getID();
+    // FIXME: Cost arbitrarily set to 1 because there doesn't seem to be a
+    // better way to determine it.
+    Cost = 1;
+  } else {
+    RegClass = TLI->getRepRegClassFor(VT)->getID();
+    Cost = TLI->getRepRegClassCostFor(VT);
+  }
+}
+
+/// Schedule - Schedule the DAG using list scheduling.
+void ScheduleDAGRRList::Schedule() {
+  DEBUG(dbgs()
+        << "********** List Scheduling BB#" << BB->getNumber()
+        << " '" << BB->getName() << "' **********\n");
+
+  CurCycle = 0;
+  IssueCount = 0;
+  MinAvailableCycle = DisableSchedCycles ? 0 : UINT_MAX;
+  NumLiveRegs = 0;
+  // Allocate slots for each physical register, plus one for a special register
+  // to track the virtual resource of a calling sequence.
+  LiveRegDefs.resize(TRI->getNumRegs() + 1, NULL);
+  LiveRegGens.resize(TRI->getNumRegs() + 1, NULL);
+  CallSeqEndForStart.clear();
+  assert(Interferences.empty() && LRegsMap.empty() && "stale Interferences");
+
+  // Build the scheduling graph.
+  BuildSchedGraph(NULL);
+
+  DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
+          SUnits[su].dumpAll(this));
+  Topo.InitDAGTopologicalSorting();
+
+  AvailableQueue->initNodes(SUnits);
+
+  HazardRec->Reset();
+
+  // Execute the actual scheduling loop.
+  ListScheduleBottomUp();
+
+  AvailableQueue->releaseState();
+
+  DEBUG({
+      dbgs() << "*** Final schedule ***\n";
+      dumpSchedule();
+      dbgs() << '\n';
+    });
+}
+
+//===----------------------------------------------------------------------===//
+//  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 ScheduleDAGRRList::ReleasePred(SUnit *SU, const SDep *PredEdge) {
+  SUnit *PredSU = PredEdge->getSUnit();
+
+#ifndef NDEBUG
+  if (PredSU->NumSuccsLeft == 0) {
+    dbgs() << "*** Scheduling failed! ***\n";
+    PredSU->dump(this);
+    dbgs() << " has been released too many times!\n";
+    llvm_unreachable(0);
+  }
+#endif
+  --PredSU->NumSuccsLeft;
+
+  if (!forceUnitLatencies()) {
+    // Updating predecessor's height. This is now the cycle when the
+    // predecessor can be scheduled without causing a pipeline stall.
+    PredSU->setHeightToAtLeast(SU->getHeight() + PredEdge->getLatency());
+  }
+
+  // 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;
+
+    unsigned Height = PredSU->getHeight();
+    if (Height < MinAvailableCycle)
+      MinAvailableCycle = Height;
+
+    if (isReady(PredSU)) {
+      AvailableQueue->push(PredSU);
+    }
+    // CapturePred and others may have left the node in the pending queue, avoid
+    // adding it twice.
+    else if (!PredSU->isPending) {
+      PredSU->isPending = true;
+      PendingQueue.push_back(PredSU);
+    }
+  }
+}
+
+/// IsChainDependent - Test if Outer is reachable from Inner through
+/// chain dependencies.
+static bool IsChainDependent(SDNode *Outer, SDNode *Inner,
+                             unsigned NestLevel,
+                             const TargetInstrInfo *TII) {
+  SDNode *N = Outer;
+  for (;;) {
+    if (N == Inner)
+      return true;
+    // For a TokenFactor, examine each operand. There may be multiple ways
+    // to get to the CALLSEQ_BEGIN, but we need to find the path with the
+    // most nesting in order to ensure that we find the corresponding match.
+    if (N->getOpcode() == ISD::TokenFactor) {
+      for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
+        if (IsChainDependent(N->getOperand(i).getNode(), Inner, NestLevel, TII))
+          return true;
+      return false;
+    }
+    // Check for a lowered CALLSEQ_BEGIN or CALLSEQ_END.
+    if (N->isMachineOpcode()) {
+      if (N->getMachineOpcode() ==
+          (unsigned)TII->getCallFrameDestroyOpcode()) {
+        ++NestLevel;
+      } else if (N->getMachineOpcode() ==
+                 (unsigned)TII->getCallFrameSetupOpcode()) {
+        if (NestLevel == 0)
+          return false;
+        --NestLevel;
+      }
+    }
+    // Otherwise, find the chain and continue climbing.
+    for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
+      if (N->getOperand(i).getValueType() == MVT::Other) {
+        N = N->getOperand(i).getNode();
+        goto found_chain_operand;
+      }
+    return false;
+  found_chain_operand:;
+    if (N->getOpcode() == ISD::EntryToken)
+      return false;
+  }
+}
+
+/// FindCallSeqStart - Starting from the (lowered) CALLSEQ_END node, locate
+/// the corresponding (lowered) CALLSEQ_BEGIN node.
+///
+/// NestLevel and MaxNested are used in recursion to indcate the current level
+/// of nesting of CALLSEQ_BEGIN and CALLSEQ_END pairs, as well as the maximum
+/// level seen so far.
+///
+/// TODO: It would be better to give CALLSEQ_END an explicit operand to point
+/// to the corresponding CALLSEQ_BEGIN to avoid needing to search for it.
+static SDNode *
+FindCallSeqStart(SDNode *N, unsigned &NestLevel, unsigned &MaxNest,
+                 const TargetInstrInfo *TII) {
+  for (;;) {
+    // For a TokenFactor, examine each operand. There may be multiple ways
+    // to get to the CALLSEQ_BEGIN, but we need to find the path with the
+    // most nesting in order to ensure that we find the corresponding match.
+    if (N->getOpcode() == ISD::TokenFactor) {
+      SDNode *Best = 0;
+      unsigned BestMaxNest = MaxNest;
+      for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
+        unsigned MyNestLevel = NestLevel;
+        unsigned MyMaxNest = MaxNest;
+        if (SDNode *New = FindCallSeqStart(N->getOperand(i).getNode(),
+                                           MyNestLevel, MyMaxNest, TII))
+          if (!Best || (MyMaxNest > BestMaxNest)) {
+            Best = New;
+            BestMaxNest = MyMaxNest;
+          }
+      }
+      assert(Best);
+      MaxNest = BestMaxNest;
+      return Best;
+    }
+    // Check for a lowered CALLSEQ_BEGIN or CALLSEQ_END.
+    if (N->isMachineOpcode()) {
+      if (N->getMachineOpcode() ==
+          (unsigned)TII->getCallFrameDestroyOpcode()) {
+        ++NestLevel;
+        MaxNest = std::max(MaxNest, NestLevel);
+      } else if (N->getMachineOpcode() ==
+                 (unsigned)TII->getCallFrameSetupOpcode()) {
+        assert(NestLevel != 0);
+        --NestLevel;
+        if (NestLevel == 0)
+          return N;
+      }
+    }
+    // Otherwise, find the chain and continue climbing.
+    for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
+      if (N->getOperand(i).getValueType() == MVT::Other) {
+        N = N->getOperand(i).getNode();
+        goto found_chain_operand;
+      }
+    return 0;
+  found_chain_operand:;
+    if (N->getOpcode() == ISD::EntryToken)
+      return 0;
+  }
+}
+
+/// Call ReleasePred for each predecessor, then update register live def/gen.
+/// Always update LiveRegDefs for a register dependence even if the current SU
+/// also defines the register. This effectively create one large live range
+/// across a sequence of two-address node. This is important because the
+/// entire chain must be scheduled together. Example:
+///
+/// flags = (3) add
+/// flags = (2) addc flags
+/// flags = (1) addc flags
+///
+/// results in
+///
+/// LiveRegDefs[flags] = 3
+/// LiveRegGens[flags] = 1
+///
+/// If (2) addc is unscheduled, then (1) addc must also be unscheduled to avoid
+/// interference on flags.
+void ScheduleDAGRRList::ReleasePredecessors(SUnit *SU) {
+  // Bottom up: release predecessors
+  for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+       I != E; ++I) {
+    ReleasePred(SU, &*I);
+    if (I->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.
+      SUnit *RegDef = LiveRegDefs[I->getReg()]; (void)RegDef;
+      assert((!RegDef || RegDef == SU || RegDef == I->getSUnit()) &&
+             "interference on register dependence");
+      LiveRegDefs[I->getReg()] = I->getSUnit();
+      if (!LiveRegGens[I->getReg()]) {
+        ++NumLiveRegs;
+        LiveRegGens[I->getReg()] = SU;
+      }
+    }
+  }
+
+  // If we're scheduling a lowered CALLSEQ_END, find the corresponding
+  // CALLSEQ_BEGIN. Inject an artificial physical register dependence between
+  // these nodes, to prevent other calls from being interscheduled with them.
+  unsigned CallResource = TRI->getNumRegs();
+  if (!LiveRegDefs[CallResource])
+    for (SDNode *Node = SU->getNode(); Node; Node = Node->getGluedNode())
+      if (Node->isMachineOpcode() &&
+          Node->getMachineOpcode() == (unsigned)TII->getCallFrameDestroyOpcode()) {
+        unsigned NestLevel = 0;
+        unsigned MaxNest = 0;
+        SDNode *N = FindCallSeqStart(Node, NestLevel, MaxNest, TII);
+
+        SUnit *Def = &SUnits[N->getNodeId()];
+        CallSeqEndForStart[Def] = SU;
+
+        ++NumLiveRegs;
+        LiveRegDefs[CallResource] = Def;
+        LiveRegGens[CallResource] = SU;
+        break;
+      }
+}
+
+/// Check to see if any of the pending instructions are ready to issue.  If
+/// so, add them to the available queue.
+void ScheduleDAGRRList::ReleasePending() {
+  if (DisableSchedCycles) {
+    assert(PendingQueue.empty() && "pending instrs not allowed in this mode");
+    return;
+  }
+
+  // If the available queue is empty, it is safe to reset MinAvailableCycle.
+  if (AvailableQueue->empty())
+    MinAvailableCycle = UINT_MAX;
+
+  // Check to see if any of the pending instructions are ready to issue.  If
+  // so, add them to the available queue.
+  for (unsigned i = 0, e = PendingQueue.size(); i != e; ++i) {
+    unsigned ReadyCycle = PendingQueue[i]->getHeight();
+    if (ReadyCycle < MinAvailableCycle)
+      MinAvailableCycle = ReadyCycle;
+
+    if (PendingQueue[i]->isAvailable) {
+      if (!isReady(PendingQueue[i]))
+          continue;
+      AvailableQueue->push(PendingQueue[i]);
+    }
+    PendingQueue[i]->isPending = false;
+    PendingQueue[i] = PendingQueue.back();
+    PendingQueue.pop_back();
+    --i; --e;
+  }
+}
+
+/// Move the scheduler state forward by the specified number of Cycles.
+void ScheduleDAGRRList::AdvanceToCycle(unsigned NextCycle) {
+  if (NextCycle <= CurCycle)
+    return;
+
+  IssueCount = 0;
+  AvailableQueue->setCurCycle(NextCycle);
+  if (!HazardRec->isEnabled()) {
+    // Bypass lots of virtual calls in case of long latency.
+    CurCycle = NextCycle;
+  }
+  else {
+    for (; CurCycle != NextCycle; ++CurCycle) {
+      HazardRec->RecedeCycle();
+    }
+  }
+  // FIXME: Instead of visiting the pending Q each time, set a dirty flag on the
+  // available Q to release pending nodes at least once before popping.
+  ReleasePending();
+}
+
+/// Move the scheduler state forward until the specified node's dependents are
+/// ready and can be scheduled with no resource conflicts.
+void ScheduleDAGRRList::AdvancePastStalls(SUnit *SU) {
+  if (DisableSchedCycles)
+    return;
+
+  // FIXME: Nodes such as CopyFromReg probably should not advance the current
+  // cycle. Otherwise, we can wrongly mask real stalls. If the non-machine node
+  // has predecessors the cycle will be advanced when they are scheduled.
+  // But given the crude nature of modeling latency though such nodes, we
+  // currently need to treat these nodes like real instructions.
+  // if (!SU->getNode() || !SU->getNode()->isMachineOpcode()) return;
+
+  unsigned ReadyCycle = SU->getHeight();
+
+  // Bump CurCycle to account for latency. We assume the latency of other
+  // available instructions may be hidden by the stall (not a full pipe stall).
+  // This updates the hazard recognizer's cycle before reserving resources for
+  // this instruction.
+  AdvanceToCycle(ReadyCycle);
+
+  // Calls are scheduled in their preceding cycle, so don't conflict with
+  // hazards from instructions after the call. EmitNode will reset the
+  // scoreboard state before emitting the call.
+  if (SU->isCall)
+    return;
+
+  // FIXME: For resource conflicts in very long non-pipelined stages, we
+  // should probably skip ahead here to avoid useless scoreboard checks.
+  int Stalls = 0;
+  while (true) {
+    ScheduleHazardRecognizer::HazardType HT =
+      HazardRec->getHazardType(SU, -Stalls);
+
+    if (HT == ScheduleHazardRecognizer::NoHazard)
+      break;
+
+    ++Stalls;
+  }
+  AdvanceToCycle(CurCycle + Stalls);
+}
+
+/// Record this SUnit in the HazardRecognizer.
+/// Does not update CurCycle.
+void ScheduleDAGRRList::EmitNode(SUnit *SU) {
+  if (!HazardRec->isEnabled())
+    return;
+
+  // Check for phys reg copy.
+  if (!SU->getNode())
+    return;
+
+  switch (SU->getNode()->getOpcode()) {
+  default:
+    assert(SU->getNode()->isMachineOpcode() &&
+           "This target-independent node should not be scheduled.");
+    break;
+  case ISD::MERGE_VALUES:
+  case ISD::TokenFactor:
+  case ISD::LIFETIME_START:
+  case ISD::LIFETIME_END:
+  case ISD::CopyToReg:
+  case ISD::CopyFromReg:
+  case ISD::EH_LABEL:
+    // Noops don't affect the scoreboard state. Copies are likely to be
+    // removed.
+    return;
+  case ISD::INLINEASM:
+    // For inline asm, clear the pipeline state.
+    HazardRec->Reset();
+    return;
+  }
+  if (SU->isCall) {
+    // Calls are scheduled with their preceding instructions. For bottom-up
+    // scheduling, clear the pipeline state before emitting.
+    HazardRec->Reset();
+  }
+
+  HazardRec->EmitInstruction(SU);
+}
+
+static void resetVRegCycle(SUnit *SU);
+
+/// 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 ScheduleDAGRRList::ScheduleNodeBottomUp(SUnit *SU) {
+  DEBUG(dbgs() << "\n*** Scheduling [" << CurCycle << "]: ");
+  DEBUG(SU->dump(this));
+
+#ifndef NDEBUG
+  if (CurCycle < SU->getHeight())
+    DEBUG(dbgs() << "   Height [" << SU->getHeight()
+          << "] pipeline stall!\n");
+#endif
+
+  // FIXME: Do not modify node height. It may interfere with
+  // backtracking. Instead add a "ready cycle" to SUnit. Before scheduling the
+  // node its ready cycle can aid heuristics, and after scheduling it can
+  // indicate the scheduled cycle.
+  SU->setHeightToAtLeast(CurCycle);
+
+  // Reserve resources for the scheduled instruction.
+  EmitNode(SU);
+
+  Sequence.push_back(SU);
+
+  AvailableQueue->scheduledNode(SU);
+
+  // If HazardRec is disabled, and each inst counts as one cycle, then
+  // advance CurCycle before ReleasePredecessors to avoid useless pushes to
+  // PendingQueue for schedulers that implement HasReadyFilter.
+  if (!HazardRec->isEnabled() && AvgIPC < 2)
+    AdvanceToCycle(CurCycle + 1);
+
+  // Update liveness of predecessors before successors to avoid treating a
+  // two-address node as a live range def.
+  ReleasePredecessors(SU);
+
+  // Release all the implicit physical register defs that are live.
+  for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
+       I != E; ++I) {
+    // LiveRegDegs[I->getReg()] != SU when SU is a two-address node.
+    if (I->isAssignedRegDep() && LiveRegDefs[I->getReg()] == SU) {
+      assert(NumLiveRegs > 0 && "NumLiveRegs is already zero!");
+      --NumLiveRegs;
+      LiveRegDefs[I->getReg()] = NULL;
+      LiveRegGens[I->getReg()] = NULL;
+      releaseInterferences(I->getReg());
+    }
+  }
+  // Release the special call resource dependence, if this is the beginning
+  // of a call.
+  unsigned CallResource = TRI->getNumRegs();
+  if (LiveRegDefs[CallResource] == SU)
+    for (const SDNode *SUNode = SU->getNode(); SUNode;
+         SUNode = SUNode->getGluedNode()) {
+      if (SUNode->isMachineOpcode() &&
+          SUNode->getMachineOpcode() == (unsigned)TII->getCallFrameSetupOpcode()) {
+        assert(NumLiveRegs > 0 && "NumLiveRegs is already zero!");
+        --NumLiveRegs;
+        LiveRegDefs[CallResource] = NULL;
+        LiveRegGens[CallResource] = NULL;
+        releaseInterferences(CallResource);
+      }
+    }
+
+  resetVRegCycle(SU);
+
+  SU->isScheduled = true;
+
+  // Conditions under which the scheduler should eagerly advance the cycle:
+  // (1) No available instructions
+  // (2) All pipelines full, so available instructions must have hazards.
+  //
+  // If HazardRec is disabled, the cycle was pre-advanced before calling
+  // ReleasePredecessors. In that case, IssueCount should remain 0.
+  //
+  // Check AvailableQueue after ReleasePredecessors in case of zero latency.
+  if (HazardRec->isEnabled() || AvgIPC > 1) {
+    if (SU->getNode() && SU->getNode()->isMachineOpcode())
+      ++IssueCount;
+    if ((HazardRec->isEnabled() && HazardRec->atIssueLimit())
+        || (!HazardRec->isEnabled() && IssueCount == AvgIPC))
+      AdvanceToCycle(CurCycle + 1);
+  }
+}
+
+/// CapturePred - This does the opposite of ReleasePred. Since SU is being
+/// unscheduled, incrcease the succ left count of its predecessors. Remove
+/// them from AvailableQueue if necessary.
+void ScheduleDAGRRList::CapturePred(SDep *PredEdge) {
+  SUnit *PredSU = PredEdge->getSUnit();
+  if (PredSU->isAvailable) {
+    PredSU->isAvailable = false;
+    if (!PredSU->isPending)
+      AvailableQueue->remove(PredSU);
+  }
+
+  assert(PredSU->NumSuccsLeft < UINT_MAX && "NumSuccsLeft will overflow!");
+  ++PredSU->NumSuccsLeft;
+}
+
+/// UnscheduleNodeBottomUp - Remove the node from the schedule, update its and
+/// its predecessor states to reflect the change.
+void ScheduleDAGRRList::UnscheduleNodeBottomUp(SUnit *SU) {
+  DEBUG(dbgs() << "*** Unscheduling [" << SU->getHeight() << "]: ");
+  DEBUG(SU->dump(this));
+
+  for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+       I != E; ++I) {
+    CapturePred(&*I);
+    if (I->isAssignedRegDep() && SU == LiveRegGens[I->getReg()]){
+      assert(NumLiveRegs > 0 && "NumLiveRegs is already zero!");
+      assert(LiveRegDefs[I->getReg()] == I->getSUnit() &&
+             "Physical register dependency violated?");
+      --NumLiveRegs;
+      LiveRegDefs[I->getReg()] = NULL;
+      LiveRegGens[I->getReg()] = NULL;
+      releaseInterferences(I->getReg());
+    }
+  }
+
+  // Reclaim the special call resource dependence, if this is the beginning
+  // of a call.
+  unsigned CallResource = TRI->getNumRegs();
+  for (const SDNode *SUNode = SU->getNode(); SUNode;
+       SUNode = SUNode->getGluedNode()) {
+    if (SUNode->isMachineOpcode() &&
+        SUNode->getMachineOpcode() == (unsigned)TII->getCallFrameSetupOpcode()) {
+      ++NumLiveRegs;
+      LiveRegDefs[CallResource] = SU;
+      LiveRegGens[CallResource] = CallSeqEndForStart[SU];
+    }
+  }
+
+  // Release the special call resource dependence, if this is the end
+  // of a call.
+  if (LiveRegGens[CallResource] == SU)
+    for (const SDNode *SUNode = SU->getNode(); SUNode;
+         SUNode = SUNode->getGluedNode()) {
+      if (SUNode->isMachineOpcode() &&
+          SUNode->getMachineOpcode() == (unsigned)TII->getCallFrameDestroyOpcode()) {
+        assert(NumLiveRegs > 0 && "NumLiveRegs is already zero!");
+        --NumLiveRegs;
+        LiveRegDefs[CallResource] = NULL;
+        LiveRegGens[CallResource] = NULL;
+        releaseInterferences(CallResource);
+      }
+    }
+
+  for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
+       I != E; ++I) {
+    if (I->isAssignedRegDep()) {
+      if (!LiveRegDefs[I->getReg()])
+        ++NumLiveRegs;
+      // This becomes the nearest def. Note that an earlier def may still be
+      // pending if this is a two-address node.
+      LiveRegDefs[I->getReg()] = SU;
+      if (LiveRegGens[I->getReg()] == NULL ||
+          I->getSUnit()->getHeight() < LiveRegGens[I->getReg()]->getHeight())
+        LiveRegGens[I->getReg()] = I->getSUnit();
+    }
+  }
+  if (SU->getHeight() < MinAvailableCycle)
+    MinAvailableCycle = SU->getHeight();
+
+  SU->setHeightDirty();
+  SU->isScheduled = false;
+  SU->isAvailable = true;
+  if (!DisableSchedCycles && AvailableQueue->hasReadyFilter()) {
+    // Don't make available until backtracking is complete.
+    SU->isPending = true;
+    PendingQueue.push_back(SU);
+  }
+  else {
+    AvailableQueue->push(SU);
+  }
+  AvailableQueue->unscheduledNode(SU);
+}
+
+/// After backtracking, the hazard checker needs to be restored to a state
+/// corresponding the current cycle.
+void ScheduleDAGRRList::RestoreHazardCheckerBottomUp() {
+  HazardRec->Reset();
+
+  unsigned LookAhead = std::min((unsigned)Sequence.size(),
+                                HazardRec->getMaxLookAhead());
+  if (LookAhead == 0)
+    return;
+
+  std::vector<SUnit*>::const_iterator I = (Sequence.end() - LookAhead);
+  unsigned HazardCycle = (*I)->getHeight();
+  for (std::vector<SUnit*>::const_iterator E = Sequence.end(); I != E; ++I) {
+    SUnit *SU = *I;
+    for (; SU->getHeight() > HazardCycle; ++HazardCycle) {
+      HazardRec->RecedeCycle();
+    }
+    EmitNode(SU);
+  }
+}
+
+/// BacktrackBottomUp - Backtrack scheduling to a previous cycle specified in
+/// BTCycle in order to schedule a specific node.
+void ScheduleDAGRRList::BacktrackBottomUp(SUnit *SU, SUnit *BtSU) {
+  SUnit *OldSU = Sequence.back();
+  while (true) {
+    Sequence.pop_back();
+    // FIXME: use ready cycle instead of height
+    CurCycle = OldSU->getHeight();
+    UnscheduleNodeBottomUp(OldSU);
+    AvailableQueue->setCurCycle(CurCycle);
+    if (OldSU == BtSU)
+      break;
+    OldSU = Sequence.back();
+  }
+
+  assert(!SU->isSucc(OldSU) && "Something is wrong!");
+
+  RestoreHazardCheckerBottomUp();
+
+  ReleasePending();
+
+  ++NumBacktracks;
+}
+
+static bool isOperandOf(const SUnit *SU, SDNode *N) {
+  for (const SDNode *SUNode = SU->getNode(); SUNode;
+       SUNode = SUNode->getGluedNode()) {
+    if (SUNode->isOperandOf(N))
+      return true;
+  }
+  return false;
+}
+
+/// CopyAndMoveSuccessors - Clone the specified node and move its scheduled
+/// successors to the newly created node.
+SUnit *ScheduleDAGRRList::CopyAndMoveSuccessors(SUnit *SU) {
+  SDNode *N = SU->getNode();
+  if (!N)
+    return NULL;
+
+  if (SU->getNode()->getGluedNode())
+    return NULL;
+
+  SUnit *NewSU;
+  bool TryUnfold = false;
+  for (unsigned i = 0, e = N->getNumValues(); i != e; ++i) {
+    EVT VT = N->getValueType(i);
+    if (VT == MVT::Glue)
+      return NULL;
+    else if (VT == MVT::Other)
+      TryUnfold = true;
+  }
+  for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
+    const SDValue &Op = N->getOperand(i);
+    EVT VT = Op.getNode()->getValueType(Op.getResNo());
+    if (VT == MVT::Glue)
+      return NULL;
+  }
+
+  if (TryUnfold) {
+    SmallVector<SDNode*, 2> NewNodes;
+    if (!TII->unfoldMemoryOperand(*DAG, N, NewNodes))
+      return NULL;
+
+    // unfolding an x86 DEC64m operation results in store, dec, load which
+    // can't be handled here so quit
+    if (NewNodes.size() == 3)
+      return NULL;
+
+    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));
+
+    // 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 = CreateNewSUnit(LoadNode);
+      LoadNode->setNodeId(LoadSU->NodeNum);
+
+      InitNumRegDefsLeft(LoadSU);
+      computeLatency(LoadSU);
+    }
+
+    SUnit *NewSU = CreateNewSUnit(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;
+
+    InitNumRegDefsLeft(NewSU);
+    computeLatency(NewSU);
+
+    // Record all the edges to and from the old SU, by category.
+    SmallVector<SDep, 4> ChainPreds;
+    SmallVector<SDep, 4> ChainSuccs;
+    SmallVector<SDep, 4> LoadPreds;
+    SmallVector<SDep, 4> NodePreds;
+    SmallVector<SDep, 4> NodeSuccs;
+    for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+         I != E; ++I) {
+      if (I->isCtrl())
+        ChainPreds.push_back(*I);
+      else if (isOperandOf(I->getSUnit(), LoadNode))
+        LoadPreds.push_back(*I);
+      else
+        NodePreds.push_back(*I);
+    }
+    for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
+         I != E; ++I) {
+      if (I->isCtrl())
+        ChainSuccs.push_back(*I);
+      else
+        NodeSuccs.push_back(*I);
+    }
+
+    // Now assign edges to the newly-created nodes.
+    for (unsigned i = 0, e = ChainPreds.size(); i != e; ++i) {
+      const SDep &Pred = ChainPreds[i];
+      RemovePred(SU, Pred);
+      if (isNewLoad)
+        AddPred(LoadSU, Pred);
+    }
+    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);
+      // Balance register pressure.
+      if (AvailableQueue->tracksRegPressure() && SuccDep->isScheduled
+          && !D.isCtrl() && NewSU->NumRegDefsLeft > 0)
+        --NewSU->NumRegDefsLeft;
+    }
+    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);
+      }
+    }
+
+    // Add a data dependency to reflect that NewSU reads the value defined
+    // by LoadSU.
+    SDep D(LoadSU, SDep::Data, 0);
+    D.setLatency(LoadSU->Latency);
+    AddPred(NewSU, D);
+
+    if (isNewLoad)
+      AvailableQueue->addNode(LoadSU);
+    AvailableQueue->addNode(NewSU);
+
+    ++NumUnfolds;
+
+    if (NewSU->NumSuccsLeft == 0) {
+      NewSU->isAvailable = true;
+      return NewSU;
+    }
+    SU = NewSU;
+  }
+
+  DEBUG(dbgs() << "    Duplicating SU #" << SU->NodeNum << "\n");
+  NewSU = CreateClone(SU);
+
+  // New SUnit has the exact same predecessors.
+  for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+       I != E; ++I)
+    if (!I->isArtificial())
+      AddPred(NewSU, *I);
+
+  // Only copy scheduled successors. Cut them from old node's successor
+  // list and move them over.
+  SmallVector<std::pair<SUnit *, SDep>, 4> DelDeps;
+  for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
+       I != E; ++I) {
+    if (I->isArtificial())
+      continue;
+    SUnit *SuccSU = I->getSUnit();
+    if (SuccSU->isScheduled) {
+      SDep D = *I;
+      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);
+
+  AvailableQueue->updateNode(SU);
+  AvailableQueue->addNode(NewSU);
+
+  ++NumDups;
+  return NewSU;
+}
+
+/// InsertCopiesAndMoveSuccs - Insert register copies and move all
+/// scheduled successors of the given SUnit to the last copy.
+void ScheduleDAGRRList::InsertCopiesAndMoveSuccs(SUnit *SU, unsigned Reg,
+                                              const TargetRegisterClass *DestRC,
+                                              const TargetRegisterClass *SrcRC,
+                                              SmallVectorImpl<SUnit*> &Copies) {
+  SUnit *CopyFromSU = CreateNewSUnit(NULL);
+  CopyFromSU->CopySrcRC = SrcRC;
+  CopyFromSU->CopyDstRC = DestRC;
+
+  SUnit *CopyToSU = CreateNewSUnit(NULL);
+  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 (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
+       I != E; ++I) {
+    if (I->isArtificial())
+      continue;
+    SUnit *SuccSU = I->getSUnit();
+    if (SuccSU->isScheduled) {
+      SDep D = *I;
+      D.setSUnit(CopyToSU);
+      AddPred(SuccSU, D);
+      DelDeps.push_back(std::make_pair(SuccSU, *I));
+    }
+    else {
+      // Avoid scheduling the def-side copy before other successors. Otherwise
+      // we could introduce another physreg interference on the copy and
+      // continue inserting copies indefinitely.
+      AddPred(SuccSU, SDep(CopyFromSU, SDep::Artificial));
+    }
+  }
+  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);
+
+  AvailableQueue->updateNode(SU);
+  AvailableQueue->addNode(CopyFromSU);
+  AvailableQueue->addNode(CopyToSU);
+  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 EVT getPhysicalRegisterVT(SDNode *N, unsigned Reg,
+                                 const TargetInstrInfo *TII) {
+  const MCInstrDesc &MCID = TII->get(N->getMachineOpcode());
+  assert(MCID.ImplicitDefs && "Physical reg def must be in implicit def list!");
+  unsigned NumRes = MCID.getNumDefs();
+  for (const uint16_t *ImpDef = MCID.getImplicitDefs(); *ImpDef; ++ImpDef) {
+    if (Reg == *ImpDef)
+      break;
+    ++NumRes;
+  }
+  return N->getValueType(NumRes);
+}
+
+/// CheckForLiveRegDef - Return true and update live register vector if the
+/// specified register def of the specified SUnit clobbers any "live" registers.
+static void CheckForLiveRegDef(SUnit *SU, unsigned Reg,
+                               std::vector<SUnit*> &LiveRegDefs,
+                               SmallSet<unsigned, 4> &RegAdded,
+                               SmallVectorImpl<unsigned> &LRegs,
+                               const TargetRegisterInfo *TRI) {
+  for (MCRegAliasIterator AliasI(Reg, TRI, true); AliasI.isValid(); ++AliasI) {
+
+    // Check if Ref is live.
+    if (!LiveRegDefs[*AliasI]) continue;
+
+    // Allow multiple uses of the same def.
+    if (LiveRegDefs[*AliasI] == SU) continue;
+
+    // Add Reg to the set of interfering live regs.
+    if (RegAdded.insert(*AliasI)) {
+      LRegs.push_back(*AliasI);
+    }
+  }
+}
+
+/// CheckForLiveRegDefMasked - Check for any live physregs that are clobbered
+/// by RegMask, and add them to LRegs.
+static void CheckForLiveRegDefMasked(SUnit *SU, const uint32_t *RegMask,
+                                     std::vector<SUnit*> &LiveRegDefs,
+                                     SmallSet<unsigned, 4> &RegAdded,
+                                     SmallVectorImpl<unsigned> &LRegs) {
+  // Look at all live registers. Skip Reg0 and the special CallResource.
+  for (unsigned i = 1, e = LiveRegDefs.size()-1; i != e; ++i) {
+    if (!LiveRegDefs[i]) continue;
+    if (LiveRegDefs[i] == SU) continue;
+    if (!MachineOperand::clobbersPhysReg(RegMask, i)) continue;
+    if (RegAdded.insert(i))
+      LRegs.push_back(i);
+  }
+}
+
+/// getNodeRegMask - Returns the register mask attached to an SDNode, if any.
+static const uint32_t *getNodeRegMask(const SDNode *N) {
+  for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
+    if (const RegisterMaskSDNode *Op =
+        dyn_cast<RegisterMaskSDNode>(N->getOperand(i).getNode()))
+      return Op->getRegMask();
+  return NULL;
+}
+
+/// 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 ScheduleDAGRRList::
+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.
+  //
+  // If SU is the currently live definition of the same register that it uses,
+  // then we are free to schedule it.
+  for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+       I != E; ++I) {
+    if (I->isAssignedRegDep() && LiveRegDefs[I->getReg()] != SU)
+      CheckForLiveRegDef(I->getSUnit(), I->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;
+    // If we're in the middle of scheduling a call, don't begin scheduling
+    // another call. Also, don't allow any physical registers to be live across
+    // the call.
+    if (Node->getMachineOpcode() == (unsigned)TII->getCallFrameDestroyOpcode()) {
+      // Check the special calling-sequence resource.
+      unsigned CallResource = TRI->getNumRegs();
+      if (LiveRegDefs[CallResource]) {
+        SDNode *Gen = LiveRegGens[CallResource]->getNode();
+        while (SDNode *Glued = Gen->getGluedNode())
+          Gen = Glued;
+        if (!IsChainDependent(Gen, Node, 0, TII) && RegAdded.insert(CallResource))
+          LRegs.push_back(CallResource);
+      }
+    }
+    if (const uint32_t *RegMask = getNodeRegMask(Node))
+      CheckForLiveRegDefMasked(SU, RegMask, LiveRegDefs, RegAdded, LRegs);
+
+    const MCInstrDesc &MCID = TII->get(Node->getMachineOpcode());
+    if (!MCID.ImplicitDefs)
+      continue;
+    for (const uint16_t *Reg = MCID.getImplicitDefs(); *Reg; ++Reg)
+      CheckForLiveRegDef(SU, *Reg, LiveRegDefs, RegAdded, LRegs, TRI);
+  }
+
+  return !LRegs.empty();
+}
+
+void ScheduleDAGRRList::releaseInterferences(unsigned Reg) {
+  // Add the nodes that aren't ready back onto the available list.
+  for (unsigned i = Interferences.size(); i > 0; --i) {
+    SUnit *SU = Interferences[i-1];
+    LRegsMapT::iterator LRegsPos = LRegsMap.find(SU);
+    if (Reg) {
+      SmallVectorImpl<unsigned> &LRegs = LRegsPos->second;
+      if (std::find(LRegs.begin(), LRegs.end(), Reg) == LRegs.end())
+        continue;
+    }
+    SU->isPending = false;
+    // The interfering node may no longer be available due to backtracking.
+    // Furthermore, it may have been made available again, in which case it is
+    // now already in the AvailableQueue.
+    if (SU->isAvailable && !SU->NodeQueueId) {
+      DEBUG(dbgs() << "    Repushing SU #" << SU->NodeNum << '\n');
+      AvailableQueue->push(SU);
+    }
+    if (i < Interferences.size())
+      Interferences[i-1] = Interferences.back();
+    Interferences.pop_back();
+    LRegsMap.erase(LRegsPos);
+  }
+}
+
+/// Return a node that can be scheduled in this cycle. Requirements:
+/// (1) Ready: latency has been satisfied
+/// (2) No Hazards: resources are available
+/// (3) No Interferences: may unschedule to break register interferences.
+SUnit *ScheduleDAGRRList::PickNodeToScheduleBottomUp() {
+  SUnit *CurSU = AvailableQueue->empty() ? 0 : AvailableQueue->pop();
+  while (CurSU) {
+    SmallVector<unsigned, 4> LRegs;
+    if (!DelayForLiveRegsBottomUp(CurSU, LRegs))
+      break;
+    DEBUG(dbgs() << "    Interfering reg " <<
+          (LRegs[0] == TRI->getNumRegs() ? "CallResource"
+           : TRI->getName(LRegs[0]))
+           << " SU #" << CurSU->NodeNum << '\n');
+    std::pair<LRegsMapT::iterator, bool> LRegsPair =
+      LRegsMap.insert(std::make_pair(CurSU, LRegs));
+    if (LRegsPair.second) {
+      CurSU->isPending = true;  // This SU is not in AvailableQueue right now.
+      Interferences.push_back(CurSU);
+    }
+    else {
+      assert(CurSU->isPending && "Intereferences are pending");
+      // Update the interference with current live regs.
+      LRegsPair.first->second = LRegs;
+    }
+    CurSU = AvailableQueue->pop();
+  }
+  if (CurSU)
+    return CurSU;
+
+  // All candidates are delayed due to live physical reg dependencies.
+  // Try backtracking, code duplication, or inserting cross class copies
+  // to resolve it.
+  for (unsigned i = 0, e = Interferences.size(); i != e; ++i) {
+    SUnit *TrySU = Interferences[i];
+    SmallVectorImpl<unsigned> &LRegs = LRegsMap[TrySU];
+
+    // Try unscheduling up to the point where it's safe to schedule
+    // this node.
+    SUnit *BtSU = NULL;
+    unsigned LiveCycle = UINT_MAX;
+    for (unsigned j = 0, ee = LRegs.size(); j != ee; ++j) {
+      unsigned Reg = LRegs[j];
+      if (LiveRegGens[Reg]->getHeight() < LiveCycle) {
+        BtSU = LiveRegGens[Reg];
+        LiveCycle = BtSU->getHeight();
+      }
+    }
+    if (!WillCreateCycle(TrySU, BtSU))  {
+      // BacktrackBottomUp mutates Interferences!
+      BacktrackBottomUp(TrySU, BtSU);
+
+      // Force the current node to be scheduled before the node that
+      // requires the physical reg dep.
+      if (BtSU->isAvailable) {
+        BtSU->isAvailable = false;
+        if (!BtSU->isPending)
+          AvailableQueue->remove(BtSU);
+      }
+      DEBUG(dbgs() << "ARTIFICIAL edge from SU(" << BtSU->NodeNum << ") to SU("
+            << TrySU->NodeNum << ")\n");
+      AddPred(TrySU, SDep(BtSU, SDep::Artificial));
+
+      // If one or more successors has been unscheduled, then the current
+      // node is no longer available.
+      if (!TrySU->isAvailable)
+        CurSU = AvailableQueue->pop();
+      else {
+        AvailableQueue->remove(TrySU);
+        CurSU = TrySU;
+      }
+      // Interferences has been mutated. We must break.
+      break;
+    }
+  }
+
+  if (!CurSU) {
+    // Can't backtrack. If it's too expensive to copy the value, then try
+    // duplicate the nodes that produces these "too expensive to copy"
+    // values to break the dependency. In case even that doesn't work,
+    // insert cross class copies.
+    // If it's not too expensive, i.e. cost != -1, issue copies.
+    SUnit *TrySU = Interferences[0];
+    SmallVectorImpl<unsigned> &LRegs = LRegsMap[TrySU];
+    assert(LRegs.size() == 1 && "Can't handle this yet!");
+    unsigned Reg = LRegs[0];
+    SUnit *LRDef = LiveRegDefs[Reg];
+    EVT 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 = 0;
+    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);
+      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();
+    }
+
+    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;
+  }
+  assert(CurSU && "Unable to resolve live physical register dependencies!");
+  return CurSU;
+}
+
+/// ListScheduleBottomUp - The main loop of list scheduling for bottom-up
+/// schedulers.
+void ScheduleDAGRRList::ListScheduleBottomUp() {
+  // Release any predecessors of the special Exit node.
+  ReleasePredecessors(&ExitSU);
+
+  // 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.
+  Sequence.reserve(SUnits.size());
+  while (!AvailableQueue->empty() || !Interferences.empty()) {
+    DEBUG(dbgs() << "\nExamining Available:\n";
+          AvailableQueue->dump(this));
+
+    // Pick the best node to schedule taking all constraints into
+    // consideration.
+    SUnit *SU = PickNodeToScheduleBottomUp();
+
+    AdvancePastStalls(SU);
+
+    ScheduleNodeBottomUp(SU);
+
+    while (AvailableQueue->empty() && !PendingQueue.empty()) {
+      // Advance the cycle to free resources. Skip ahead to the next ready SU.
+      assert(MinAvailableCycle < UINT_MAX && "MinAvailableCycle uninitialized");
+      AdvanceToCycle(std::max(CurCycle + 1, MinAvailableCycle));
+    }
+  }
+
+  // Reverse the order if it is bottom up.
+  std::reverse(Sequence.begin(), Sequence.end());
+
+#ifndef NDEBUG
+  VerifyScheduledSequence(/*isBottomUp=*/true);
+#endif
+}
+
+//===----------------------------------------------------------------------===//
+//                RegReductionPriorityQueue Definition
+//===----------------------------------------------------------------------===//
+//
+// This is a SchedulingPriorityQueue that schedules using Sethi Ullman numbers
+// to reduce register pressure.
+//
+namespace {
+class RegReductionPQBase;
+
+struct queue_sort : public std::binary_function<SUnit*, SUnit*, bool> {
+  bool isReady(SUnit* SU, unsigned CurCycle) const { return true; }
+};
+
+#ifndef NDEBUG
+template<class SF>
+struct reverse_sort : public queue_sort {
+  SF &SortFunc;
+  reverse_sort(SF &sf) : SortFunc(sf) {}
+  reverse_sort(const reverse_sort &RHS) : SortFunc(RHS.SortFunc) {}
+
+  bool operator()(SUnit* left, SUnit* right) const {
+    // reverse left/right rather than simply !SortFunc(left, right)
+    // to expose different paths in the comparison logic.
+    return SortFunc(right, left);
+  }
+};
+#endif // NDEBUG
+
+/// bu_ls_rr_sort - Priority function for bottom up register pressure
+// reduction scheduler.
+struct bu_ls_rr_sort : public queue_sort {
+  enum {
+    IsBottomUp = true,
+    HasReadyFilter = false
+  };
+
+  RegReductionPQBase *SPQ;
+  bu_ls_rr_sort(RegReductionPQBase *spq) : SPQ(spq) {}
+  bu_ls_rr_sort(const bu_ls_rr_sort &RHS) : SPQ(RHS.SPQ) {}
+
+  bool operator()(SUnit* left, SUnit* right) const;
+};
+
+// src_ls_rr_sort - Priority function for source order scheduler.
+struct src_ls_rr_sort : public queue_sort {
+  enum {
+    IsBottomUp = true,
+    HasReadyFilter = false
+  };
+
+  RegReductionPQBase *SPQ;
+  src_ls_rr_sort(RegReductionPQBase *spq)
+    : SPQ(spq) {}
+  src_ls_rr_sort(const src_ls_rr_sort &RHS)
+    : SPQ(RHS.SPQ) {}
+
+  bool operator()(SUnit* left, SUnit* right) const;
+};
+
+// hybrid_ls_rr_sort - Priority function for hybrid scheduler.
+struct hybrid_ls_rr_sort : public queue_sort {
+  enum {
+    IsBottomUp = true,
+    HasReadyFilter = false
+  };
+
+  RegReductionPQBase *SPQ;
+  hybrid_ls_rr_sort(RegReductionPQBase *spq)
+    : SPQ(spq) {}
+  hybrid_ls_rr_sort(const hybrid_ls_rr_sort &RHS)
+    : SPQ(RHS.SPQ) {}
+
+  bool isReady(SUnit *SU, unsigned CurCycle) const;
+
+  bool operator()(SUnit* left, SUnit* right) const;
+};
+
+// ilp_ls_rr_sort - Priority function for ILP (instruction level parallelism)
+// scheduler.
+struct ilp_ls_rr_sort : public queue_sort {
+  enum {
+    IsBottomUp = true,
+    HasReadyFilter = false
+  };
+
+  RegReductionPQBase *SPQ;
+  ilp_ls_rr_sort(RegReductionPQBase *spq)
+    : SPQ(spq) {}
+  ilp_ls_rr_sort(const ilp_ls_rr_sort &RHS)
+    : SPQ(RHS.SPQ) {}
+
+  bool isReady(SUnit *SU, unsigned CurCycle) const;
+
+  bool operator()(SUnit* left, SUnit* right) const;
+};
+
+class RegReductionPQBase : public SchedulingPriorityQueue {
+protected:
+  std::vector<SUnit*> Queue;
+  unsigned CurQueueId;
+  bool TracksRegPressure;
+  bool SrcOrder;
+
+  // SUnits - The SUnits for the current graph.
+  std::vector<SUnit> *SUnits;
+
+  MachineFunction &MF;
+  const TargetInstrInfo *TII;
+  const TargetRegisterInfo *TRI;
+  const TargetLowering *TLI;
+  ScheduleDAGRRList *scheduleDAG;
+
+  // SethiUllmanNumbers - The SethiUllman number for each node.
+  std::vector<unsigned> SethiUllmanNumbers;
+
+  /// RegPressure - Tracking current reg pressure per register class.
+  ///
+  std::vector<unsigned> RegPressure;
+
+  /// RegLimit - Tracking the number of allocatable registers per register
+  /// class.
+  std::vector<unsigned> RegLimit;
+
+public:
+  RegReductionPQBase(MachineFunction &mf,
+                     bool hasReadyFilter,
+                     bool tracksrp,
+                     bool srcorder,
+                     const TargetInstrInfo *tii,
+                     const TargetRegisterInfo *tri,
+                     const TargetLowering *tli)
+    : SchedulingPriorityQueue(hasReadyFilter),
+      CurQueueId(0), TracksRegPressure(tracksrp), SrcOrder(srcorder),
+      MF(mf), TII(tii), TRI(tri), TLI(tli), scheduleDAG(NULL) {
+    if (TracksRegPressure) {
+      unsigned NumRC = TRI->getNumRegClasses();
+      RegLimit.resize(NumRC);
+      RegPressure.resize(NumRC);
+      std::fill(RegLimit.begin(), RegLimit.end(), 0);
+      std::fill(RegPressure.begin(), RegPressure.end(), 0);
+      for (TargetRegisterInfo::regclass_iterator I = TRI->regclass_begin(),
+             E = TRI->regclass_end(); I != E; ++I)
+        RegLimit[(*I)->getID()] = tri->getRegPressureLimit(*I, MF);
+    }
+  }
+
+  void setScheduleDAG(ScheduleDAGRRList *scheduleDag) {
+    scheduleDAG = scheduleDag;
+  }
+
+  ScheduleHazardRecognizer* getHazardRec() {
+    return scheduleDAG->getHazardRec();
+  }
+
+  void initNodes(std::vector<SUnit> &sunits);
+
+  void addNode(const SUnit *SU);
+
+  void updateNode(const SUnit *SU);
+
+  void releaseState() {
+    SUnits = 0;
+    SethiUllmanNumbers.clear();
+    std::fill(RegPressure.begin(), RegPressure.end(), 0);
+  }
+
+  unsigned getNodePriority(const SUnit *SU) const;
+
+  unsigned getNodeOrdering(const SUnit *SU) const {
+    if (!SU->getNode()) return 0;
+
+    return SU->getNode()->getIROrder();
+  }
+
+  bool empty() const { return Queue.empty(); }
+
+  void push(SUnit *U) {
+    assert(!U->NodeQueueId && "Node in the queue already");
+    U->NodeQueueId = ++CurQueueId;
+    Queue.push_back(U);
+  }
+
+  void remove(SUnit *SU) {
+    assert(!Queue.empty() && "Queue is empty!");
+    assert(SU->NodeQueueId != 0 && "Not in queue!");
+    std::vector<SUnit *>::iterator I = std::find(Queue.begin(), Queue.end(),
+                                                 SU);
+    if (I != prior(Queue.end()))
+      std::swap(*I, Queue.back());
+    Queue.pop_back();
+    SU->NodeQueueId = 0;
+  }
+
+  bool tracksRegPressure() const { return TracksRegPressure; }
+
+  void dumpRegPressure() const;
+
+  bool HighRegPressure(const SUnit *SU) const;
+
+  bool MayReduceRegPressure(SUnit *SU) const;
+
+  int RegPressureDiff(SUnit *SU, unsigned &LiveUses) const;
+
+  void scheduledNode(SUnit *SU);
+
+  void unscheduledNode(SUnit *SU);
+
+protected:
+  bool canClobber(const SUnit *SU, const SUnit *Op);
+  void AddPseudoTwoAddrDeps();
+  void PrescheduleNodesWithMultipleUses();
+  void CalculateSethiUllmanNumbers();
+};
+
+template<class SF>
+static SUnit *popFromQueueImpl(std::vector<SUnit*> &Q, SF &Picker) {
+  std::vector<SUnit *>::iterator Best = Q.begin();
+  for (std::vector<SUnit *>::iterator I = llvm::next(Q.begin()),
+         E = Q.end(); I != E; ++I)
+    if (Picker(*Best, *I))
+      Best = I;
+  SUnit *V = *Best;
+  if (Best != prior(Q.end()))
+    std::swap(*Best, Q.back());
+  Q.pop_back();
+  return V;
+}
+
+template<class SF>
+SUnit *popFromQueue(std::vector<SUnit*> &Q, SF &Picker, ScheduleDAG *DAG) {
+#ifndef NDEBUG
+  if (DAG->StressSched) {
+    reverse_sort<SF> RPicker(Picker);
+    return popFromQueueImpl(Q, RPicker);
+  }
+#endif
+  (void)DAG;
+  return popFromQueueImpl(Q, Picker);
+}
+
+template<class SF>
+class RegReductionPriorityQueue : public RegReductionPQBase {
+  SF Picker;
+
+public:
+  RegReductionPriorityQueue(MachineFunction &mf,
+                            bool tracksrp,
+                            bool srcorder,
+                            const TargetInstrInfo *tii,
+                            const TargetRegisterInfo *tri,
+                            const TargetLowering *tli)
+    : RegReductionPQBase(mf, SF::HasReadyFilter, tracksrp, srcorder,
+                         tii, tri, tli),
+      Picker(this) {}
+
+  bool isBottomUp() const { return SF::IsBottomUp; }
+
+  bool isReady(SUnit *U) const {
+    return Picker.HasReadyFilter && Picker.isReady(U, getCurCycle());
+  }
+
+  SUnit *pop() {
+    if (Queue.empty()) return NULL;
+
+    SUnit *V = popFromQueue(Queue, Picker, scheduleDAG);
+    V->NodeQueueId = 0;
+    return V;
+  }
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+  void dump(ScheduleDAG *DAG) const {
+    // Emulate pop() without clobbering NodeQueueIds.
+    std::vector<SUnit*> DumpQueue = Queue;
+    SF DumpPicker = Picker;
+    while (!DumpQueue.empty()) {
+      SUnit *SU = popFromQueue(DumpQueue, DumpPicker, scheduleDAG);
+      dbgs() << "Height " << SU->getHeight() << ": ";
+      SU->dump(DAG);
+    }
+  }
+#endif
+};
+
+typedef RegReductionPriorityQueue<bu_ls_rr_sort>
+BURegReductionPriorityQueue;
+
+typedef RegReductionPriorityQueue<src_ls_rr_sort>
+SrcRegReductionPriorityQueue;
+
+typedef RegReductionPriorityQueue<hybrid_ls_rr_sort>
+HybridBURRPriorityQueue;
+
+typedef RegReductionPriorityQueue<ilp_ls_rr_sort>
+ILPBURRPriorityQueue;
+} // end anonymous namespace
+
+//===----------------------------------------------------------------------===//
+//           Static Node Priority for Register Pressure Reduction
+//===----------------------------------------------------------------------===//
+
+// Check for special nodes that bypass scheduling heuristics.
+// Currently this pushes TokenFactor nodes down, but may be used for other
+// pseudo-ops as well.
+//
+// Return -1 to schedule right above left, 1 for left above right.
+// Return 0 if no bias exists.
+static int checkSpecialNodes(const SUnit *left, const SUnit *right) {
+  bool LSchedLow = left->isScheduleLow;
+  bool RSchedLow = right->isScheduleLow;
+  if (LSchedLow != RSchedLow)
+    return LSchedLow < RSchedLow ? 1 : -1;
+  return 0;
+}
+
+/// CalcNodeSethiUllmanNumber - Compute Sethi Ullman number.
+/// Smaller number is the higher priority.
+static unsigned
+CalcNodeSethiUllmanNumber(const SUnit *SU, std::vector<unsigned> &SUNumbers) {
+  unsigned &SethiUllmanNumber = SUNumbers[SU->NodeNum];
+  if (SethiUllmanNumber != 0)
+    return SethiUllmanNumber;
+
+  unsigned Extra = 0;
+  for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+       I != E; ++I) {
+    if (I->isCtrl()) continue;  // ignore chain preds
+    SUnit *PredSU = I->getSUnit();
+    unsigned PredSethiUllman = CalcNodeSethiUllmanNumber(PredSU, SUNumbers);
+    if (PredSethiUllman > SethiUllmanNumber) {
+      SethiUllmanNumber = PredSethiUllman;
+      Extra = 0;
+    } else if (PredSethiUllman == SethiUllmanNumber)
+      ++Extra;
+  }
+
+  SethiUllmanNumber += Extra;
+
+  if (SethiUllmanNumber == 0)
+    SethiUllmanNumber = 1;
+
+  return SethiUllmanNumber;
+}
+
+/// CalculateSethiUllmanNumbers - Calculate Sethi-Ullman numbers of all
+/// scheduling units.
+void RegReductionPQBase::CalculateSethiUllmanNumbers() {
+  SethiUllmanNumbers.assign(SUnits->size(), 0);
+
+  for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
+    CalcNodeSethiUllmanNumber(&(*SUnits)[i], SethiUllmanNumbers);
+}
+
+void RegReductionPQBase::addNode(const SUnit *SU) {
+  unsigned SUSize = SethiUllmanNumbers.size();
+  if (SUnits->size() > SUSize)
+    SethiUllmanNumbers.resize(SUSize*2, 0);
+  CalcNodeSethiUllmanNumber(SU, SethiUllmanNumbers);
+}
+
+void RegReductionPQBase::updateNode(const SUnit *SU) {
+  SethiUllmanNumbers[SU->NodeNum] = 0;
+  CalcNodeSethiUllmanNumber(SU, SethiUllmanNumbers);
+}
+
+// Lower priority means schedule further down. For bottom-up scheduling, lower
+// priority SUs are scheduled before higher priority SUs.
+unsigned RegReductionPQBase::getNodePriority(const SUnit *SU) const {
+  assert(SU->NodeNum < SethiUllmanNumbers.size());
+  unsigned Opc = SU->getNode() ? SU->getNode()->getOpcode() : 0;
+  if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
+    // CopyToReg should be close to its uses to facilitate coalescing and
+    // avoid spilling.
+    return 0;
+  if (Opc == TargetOpcode::EXTRACT_SUBREG ||
+      Opc == TargetOpcode::SUBREG_TO_REG ||
+      Opc == TargetOpcode::INSERT_SUBREG)
+    // EXTRACT_SUBREG, INSERT_SUBREG, and SUBREG_TO_REG nodes should be
+    // close to their uses to facilitate coalescing.
+    return 0;
+  if (SU->NumSuccs == 0 && SU->NumPreds != 0)
+    // If SU does not have a register use, i.e. it doesn't produce a value
+    // that would be consumed (e.g. store), then it terminates a chain of
+    // computation.  Give it a large SethiUllman number so it will be
+    // scheduled right before its predecessors that it doesn't lengthen
+    // their live ranges.
+    return 0xffff;
+  if (SU->NumPreds == 0 && SU->NumSuccs != 0)
+    // If SU does not have a register def, schedule it close to its uses
+    // because it does not lengthen any live ranges.
+    return 0;
+#if 1
+  return SethiUllmanNumbers[SU->NodeNum];
+#else
+  unsigned Priority = SethiUllmanNumbers[SU->NodeNum];
+  if (SU->isCallOp) {
+    // FIXME: This assumes all of the defs are used as call operands.
+    int NP = (int)Priority - SU->getNode()->getNumValues();
+    return (NP > 0) ? NP : 0;
+  }
+  return Priority;
+#endif
+}
+
+//===----------------------------------------------------------------------===//
+//                     Register Pressure Tracking
+//===----------------------------------------------------------------------===//
+
+void RegReductionPQBase::dumpRegPressure() const {
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+  for (TargetRegisterInfo::regclass_iterator I = TRI->regclass_begin(),
+         E = TRI->regclass_end(); I != E; ++I) {
+    const TargetRegisterClass *RC = *I;
+    unsigned Id = RC->getID();
+    unsigned RP = RegPressure[Id];
+    if (!RP) continue;
+    DEBUG(dbgs() << RC->getName() << ": " << RP << " / " << RegLimit[Id]
+          << '\n');
+  }
+#endif
+}
+
+bool RegReductionPQBase::HighRegPressure(const SUnit *SU) const {
+  if (!TLI)
+    return false;
+
+  for (SUnit::const_pred_iterator I = SU->Preds.begin(),E = SU->Preds.end();
+       I != E; ++I) {
+    if (I->isCtrl())
+      continue;
+    SUnit *PredSU = I->getSUnit();
+    // NumRegDefsLeft is zero when enough uses of this node have been scheduled
+    // to cover the number of registers defined (they are all live).
+    if (PredSU->NumRegDefsLeft == 0) {
+      continue;
+    }
+    for (ScheduleDAGSDNodes::RegDefIter RegDefPos(PredSU, scheduleDAG);
+         RegDefPos.IsValid(); RegDefPos.Advance()) {
+      unsigned RCId, Cost;
+      GetCostForDef(RegDefPos, TLI, TII, TRI, RCId, Cost, MF);
+
+      if ((RegPressure[RCId] + Cost) >= RegLimit[RCId])
+        return true;
+    }
+  }
+  return false;
+}
+
+bool RegReductionPQBase::MayReduceRegPressure(SUnit *SU) const {
+  const SDNode *N = SU->getNode();
+
+  if (!N->isMachineOpcode() || !SU->NumSuccs)
+    return false;
+
+  unsigned NumDefs = TII->get(N->getMachineOpcode()).getNumDefs();
+  for (unsigned i = 0; i != NumDefs; ++i) {
+    MVT VT = N->getSimpleValueType(i);
+    if (!N->hasAnyUseOfValue(i))
+      continue;
+    unsigned RCId = TLI->getRepRegClassFor(VT)->getID();
+    if (RegPressure[RCId] >= RegLimit[RCId])
+      return true;
+  }
+  return false;
+}
+
+// Compute the register pressure contribution by this instruction by count up
+// for uses that are not live and down for defs. Only count register classes
+// that are already under high pressure. As a side effect, compute the number of
+// uses of registers that are already live.
+//
+// FIXME: This encompasses the logic in HighRegPressure and MayReduceRegPressure
+// so could probably be factored.
+int RegReductionPQBase::RegPressureDiff(SUnit *SU, unsigned &LiveUses) const {
+  LiveUses = 0;
+  int PDiff = 0;
+  for (SUnit::const_pred_iterator I = SU->Preds.begin(),E = SU->Preds.end();
+       I != E; ++I) {
+    if (I->isCtrl())
+      continue;
+    SUnit *PredSU = I->getSUnit();
+    // NumRegDefsLeft is zero when enough uses of this node have been scheduled
+    // to cover the number of registers defined (they are all live).
+    if (PredSU->NumRegDefsLeft == 0) {
+      if (PredSU->getNode()->isMachineOpcode())
+        ++LiveUses;
+      continue;
+    }
+    for (ScheduleDAGSDNodes::RegDefIter RegDefPos(PredSU, scheduleDAG);
+         RegDefPos.IsValid(); RegDefPos.Advance()) {
+      MVT VT = RegDefPos.GetValue();
+      unsigned RCId = TLI->getRepRegClassFor(VT)->getID();
+      if (RegPressure[RCId] >= RegLimit[RCId])
+        ++PDiff;
+    }
+  }
+  const SDNode *N = SU->getNode();
+
+  if (!N || !N->isMachineOpcode() || !SU->NumSuccs)
+    return PDiff;
+
+  unsigned NumDefs = TII->get(N->getMachineOpcode()).getNumDefs();
+  for (unsigned i = 0; i != NumDefs; ++i) {
+    MVT VT = N->getSimpleValueType(i);
+    if (!N->hasAnyUseOfValue(i))
+      continue;
+    unsigned RCId = TLI->getRepRegClassFor(VT)->getID();
+    if (RegPressure[RCId] >= RegLimit[RCId])
+      --PDiff;
+  }
+  return PDiff;
+}
+
+void RegReductionPQBase::scheduledNode(SUnit *SU) {
+  if (!TracksRegPressure)
+    return;
+
+  if (!SU->getNode())
+    return;
+
+  for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+       I != E; ++I) {
+    if (I->isCtrl())
+      continue;
+    SUnit *PredSU = I->getSUnit();
+    // NumRegDefsLeft is zero when enough uses of this node have been scheduled
+    // to cover the number of registers defined (they are all live).
+    if (PredSU->NumRegDefsLeft == 0) {
+      continue;
+    }
+    // FIXME: The ScheduleDAG currently loses information about which of a
+    // node's values is consumed by each dependence. Consequently, if the node
+    // defines multiple register classes, we don't know which to pressurize
+    // here. Instead the following loop consumes the register defs in an
+    // arbitrary order. At least it handles the common case of clustered loads
+    // to the same class. For precise liveness, each SDep needs to indicate the
+    // result number. But that tightly couples the ScheduleDAG with the
+    // SelectionDAG making updates tricky. A simpler hack would be to attach a
+    // value type or register class to SDep.
+    //
+    // The most important aspect of register tracking is balancing the increase
+    // here with the reduction further below. Note that this SU may use multiple
+    // defs in PredSU. The can't be determined here, but we've already
+    // compensated by reducing NumRegDefsLeft in PredSU during
+    // ScheduleDAGSDNodes::AddSchedEdges.
+    --PredSU->NumRegDefsLeft;
+    unsigned SkipRegDefs = PredSU->NumRegDefsLeft;
+    for (ScheduleDAGSDNodes::RegDefIter RegDefPos(PredSU, scheduleDAG);
+         RegDefPos.IsValid(); RegDefPos.Advance(), --SkipRegDefs) {
+      if (SkipRegDefs)
+        continue;
+
+      unsigned RCId, Cost;
+      GetCostForDef(RegDefPos, TLI, TII, TRI, RCId, Cost, MF);
+      RegPressure[RCId] += Cost;
+      break;
+    }
+  }
+
+  // We should have this assert, but there may be dead SDNodes that never
+  // materialize as SUnits, so they don't appear to generate liveness.
+  //assert(SU->NumRegDefsLeft == 0 && "not all regdefs have scheduled uses");
+  int SkipRegDefs = (int)SU->NumRegDefsLeft;
+  for (ScheduleDAGSDNodes::RegDefIter RegDefPos(SU, scheduleDAG);
+       RegDefPos.IsValid(); RegDefPos.Advance(), --SkipRegDefs) {
+    if (SkipRegDefs > 0)
+      continue;
+    unsigned RCId, Cost;
+    GetCostForDef(RegDefPos, TLI, TII, TRI, RCId, Cost, MF);
+    if (RegPressure[RCId] < Cost) {
+      // Register pressure tracking is imprecise. This can happen. But we try
+      // hard not to let it happen because it likely results in poor scheduling.
+      DEBUG(dbgs() << "  SU(" << SU->NodeNum << ") has too many regdefs\n");
+      RegPressure[RCId] = 0;
+    }
+    else {
+      RegPressure[RCId] -= Cost;
+    }
+  }
+  dumpRegPressure();
+}
+
+void RegReductionPQBase::unscheduledNode(SUnit *SU) {
+  if (!TracksRegPressure)
+    return;
+
+  const SDNode *N = SU->getNode();
+  if (!N) return;
+
+  if (!N->isMachineOpcode()) {
+    if (N->getOpcode() != ISD::CopyToReg)
+      return;
+  } else {
+    unsigned Opc = N->getMachineOpcode();
+    if (Opc == TargetOpcode::EXTRACT_SUBREG ||
+        Opc == TargetOpcode::INSERT_SUBREG ||
+        Opc == TargetOpcode::SUBREG_TO_REG ||
+        Opc == TargetOpcode::REG_SEQUENCE ||
+        Opc == TargetOpcode::IMPLICIT_DEF)
+      return;
+  }
+
+  for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+       I != E; ++I) {
+    if (I->isCtrl())
+      continue;
+    SUnit *PredSU = I->getSUnit();
+    // NumSuccsLeft counts all deps. Don't compare it with NumSuccs which only
+    // counts data deps.
+    if (PredSU->NumSuccsLeft != PredSU->Succs.size())
+      continue;
+    const SDNode *PN = PredSU->getNode();
+    if (!PN->isMachineOpcode()) {
+      if (PN->getOpcode() == ISD::CopyFromReg) {
+        MVT VT = PN->getSimpleValueType(0);
+        unsigned RCId = TLI->getRepRegClassFor(VT)->getID();
+        RegPressure[RCId] += TLI->getRepRegClassCostFor(VT);
+      }
+      continue;
+    }
+    unsigned POpc = PN->getMachineOpcode();
+    if (POpc == TargetOpcode::IMPLICIT_DEF)
+      continue;
+    if (POpc == TargetOpcode::EXTRACT_SUBREG ||
+        POpc == TargetOpcode::INSERT_SUBREG ||
+        POpc == TargetOpcode::SUBREG_TO_REG) {
+      MVT VT = PN->getSimpleValueType(0);
+      unsigned RCId = TLI->getRepRegClassFor(VT)->getID();
+      RegPressure[RCId] += TLI->getRepRegClassCostFor(VT);
+      continue;
+    }
+    unsigned NumDefs = TII->get(PN->getMachineOpcode()).getNumDefs();
+    for (unsigned i = 0; i != NumDefs; ++i) {
+      MVT VT = PN->getSimpleValueType(i);
+      if (!PN->hasAnyUseOfValue(i))
+        continue;
+      unsigned RCId = TLI->getRepRegClassFor(VT)->getID();
+      if (RegPressure[RCId] < TLI->getRepRegClassCostFor(VT))
+        // Register pressure tracking is imprecise. This can happen.
+        RegPressure[RCId] = 0;
+      else
+        RegPressure[RCId] -= TLI->getRepRegClassCostFor(VT);
+    }
+  }
+
+  // Check for isMachineOpcode() as PrescheduleNodesWithMultipleUses()
+  // may transfer data dependencies to CopyToReg.
+  if (SU->NumSuccs && N->isMachineOpcode()) {
+    unsigned NumDefs = TII->get(N->getMachineOpcode()).getNumDefs();
+    for (unsigned i = NumDefs, e = N->getNumValues(); i != e; ++i) {
+      MVT VT = N->getSimpleValueType(i);
+      if (VT == MVT::Glue || VT == MVT::Other)
+        continue;
+      if (!N->hasAnyUseOfValue(i))
+        continue;
+      unsigned RCId = TLI->getRepRegClassFor(VT)->getID();
+      RegPressure[RCId] += TLI->getRepRegClassCostFor(VT);
+    }
+  }
+
+  dumpRegPressure();
+}
+
+//===----------------------------------------------------------------------===//
+//           Dynamic Node Priority for Register Pressure Reduction
+//===----------------------------------------------------------------------===//
+
+/// closestSucc - Returns the scheduled cycle of the successor which is
+/// closest to the current cycle.
+static unsigned closestSucc(const SUnit *SU) {
+  unsigned MaxHeight = 0;
+  for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
+       I != E; ++I) {
+    if (I->isCtrl()) continue;  // ignore chain succs
+    unsigned Height = I->getSUnit()->getHeight();
+    // If there are bunch of CopyToRegs stacked up, they should be considered
+    // to be at the same position.
+    if (I->getSUnit()->getNode() &&
+        I->getSUnit()->getNode()->getOpcode() == ISD::CopyToReg)
+      Height = closestSucc(I->getSUnit())+1;
+    if (Height > MaxHeight)
+      MaxHeight = Height;
+  }
+  return MaxHeight;
+}
+
+/// calcMaxScratches - Returns an cost estimate of the worse case requirement
+/// for scratch registers, i.e. number of data dependencies.
+static unsigned calcMaxScratches(const SUnit *SU) {
+  unsigned Scratches = 0;
+  for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+       I != E; ++I) {
+    if (I->isCtrl()) continue;  // ignore chain preds
+    Scratches++;
+  }
+  return Scratches;
+}
+
+/// hasOnlyLiveInOpers - Return true if SU has only value predecessors that are
+/// CopyFromReg from a virtual register.
+static bool hasOnlyLiveInOpers(const SUnit *SU) {
+  bool RetVal = false;
+  for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+       I != E; ++I) {
+    if (I->isCtrl()) continue;
+    const SUnit *PredSU = I->getSUnit();
+    if (PredSU->getNode() &&
+        PredSU->getNode()->getOpcode() == ISD::CopyFromReg) {
+      unsigned Reg =
+        cast<RegisterSDNode>(PredSU->getNode()->getOperand(1))->getReg();
+      if (TargetRegisterInfo::isVirtualRegister(Reg)) {
+        RetVal = true;
+        continue;
+      }
+    }
+    return false;
+  }
+  return RetVal;
+}
+
+/// hasOnlyLiveOutUses - Return true if SU has only value successors that are
+/// CopyToReg to a virtual register. This SU def is probably a liveout and
+/// it has no other use. It should be scheduled closer to the terminator.
+static bool hasOnlyLiveOutUses(const SUnit *SU) {
+  bool RetVal = false;
+  for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
+       I != E; ++I) {
+    if (I->isCtrl()) continue;
+    const SUnit *SuccSU = I->getSUnit();
+    if (SuccSU->getNode() && SuccSU->getNode()->getOpcode() == ISD::CopyToReg) {
+      unsigned Reg =
+        cast<RegisterSDNode>(SuccSU->getNode()->getOperand(1))->getReg();
+      if (TargetRegisterInfo::isVirtualRegister(Reg)) {
+        RetVal = true;
+        continue;
+      }
+    }
+    return false;
+  }
+  return RetVal;
+}
+
+// Set isVRegCycle for a node with only live in opers and live out uses. Also
+// set isVRegCycle for its CopyFromReg operands.
+//
+// This is only relevant for single-block loops, in which case the VRegCycle
+// node is likely an induction variable in which the operand and target virtual
+// registers should be coalesced (e.g. pre/post increment values). Setting the
+// isVRegCycle flag helps the scheduler prioritize other uses of the same
+// CopyFromReg so that this node becomes the virtual register "kill". This
+// avoids interference between the values live in and out of the block and
+// eliminates a copy inside the loop.
+static void initVRegCycle(SUnit *SU) {
+  if (DisableSchedVRegCycle)
+    return;
+
+  if (!hasOnlyLiveInOpers(SU) || !hasOnlyLiveOutUses(SU))
+    return;
+
+  DEBUG(dbgs() << "VRegCycle: SU(" << SU->NodeNum << ")\n");
+
+  SU->isVRegCycle = true;
+
+  for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+       I != E; ++I) {
+    if (I->isCtrl()) continue;
+    I->getSUnit()->isVRegCycle = true;
+  }
+}
+
+// After scheduling the definition of a VRegCycle, clear the isVRegCycle flag of
+// CopyFromReg operands. We should no longer penalize other uses of this VReg.
+static void resetVRegCycle(SUnit *SU) {
+  if (!SU->isVRegCycle)
+    return;
+
+  for (SUnit::const_pred_iterator I = SU->Preds.begin(),E = SU->Preds.end();
+       I != E; ++I) {
+    if (I->isCtrl()) continue;  // ignore chain preds
+    SUnit *PredSU = I->getSUnit();
+    if (PredSU->isVRegCycle) {
+      assert(PredSU->getNode()->getOpcode() == ISD::CopyFromReg &&
+             "VRegCycle def must be CopyFromReg");
+      I->getSUnit()->isVRegCycle = 0;
+    }
+  }
+}
+
+// Return true if this SUnit uses a CopyFromReg node marked as a VRegCycle. This
+// means a node that defines the VRegCycle has not been scheduled yet.
+static bool hasVRegCycleUse(const SUnit *SU) {
+  // If this SU also defines the VReg, don't hoist it as a "use".
+  if (SU->isVRegCycle)
+    return false;
+
+  for (SUnit::const_pred_iterator I = SU->Preds.begin(),E = SU->Preds.end();
+       I != E; ++I) {
+    if (I->isCtrl()) continue;  // ignore chain preds
+    if (I->getSUnit()->isVRegCycle &&
+        I->getSUnit()->getNode()->getOpcode() == ISD::CopyFromReg) {
+      DEBUG(dbgs() << "  VReg cycle use: SU (" << SU->NodeNum << ")\n");
+      return true;
+    }
+  }
+  return false;
+}
+
+// Check for either a dependence (latency) or resource (hazard) stall.
+//
+// Note: The ScheduleHazardRecognizer interface requires a non-const SU.
+static bool BUHasStall(SUnit *SU, int Height, RegReductionPQBase *SPQ) {
+  if ((int)SPQ->getCurCycle() < Height) return true;
+  if (SPQ->getHazardRec()->getHazardType(SU, 0)
+      != ScheduleHazardRecognizer::NoHazard)
+    return true;
+  return false;
+}
+
+// Return -1 if left has higher priority, 1 if right has higher priority.
+// Return 0 if latency-based priority is equivalent.
+static int BUCompareLatency(SUnit *left, SUnit *right, bool checkPref,
+                            RegReductionPQBase *SPQ) {
+  // Scheduling an instruction that uses a VReg whose postincrement has not yet
+  // been scheduled will induce a copy. Model this as an extra cycle of latency.
+  int LPenalty = hasVRegCycleUse(left) ? 1 : 0;
+  int RPenalty = hasVRegCycleUse(right) ? 1 : 0;
+  int LHeight = (int)left->getHeight() + LPenalty;
+  int RHeight = (int)right->getHeight() + RPenalty;
+
+  bool LStall = (!checkPref || left->SchedulingPref == Sched::ILP) &&
+    BUHasStall(left, LHeight, SPQ);
+  bool RStall = (!checkPref || right->SchedulingPref == Sched::ILP) &&
+    BUHasStall(right, RHeight, SPQ);
+
+  // If scheduling one of the node will cause a pipeline stall, delay it.
+  // If scheduling either one of the node will cause a pipeline stall, sort
+  // them according to their height.
+  if (LStall) {
+    if (!RStall)
+      return 1;
+    if (LHeight != RHeight)
+      return LHeight > RHeight ? 1 : -1;
+  } else if (RStall)
+    return -1;
+
+  // If either node is scheduling for latency, sort them by height/depth
+  // and latency.
+  if (!checkPref || (left->SchedulingPref == Sched::ILP ||
+                     right->SchedulingPref == Sched::ILP)) {
+    // If neither instruction stalls (!LStall && !RStall) and HazardRecognizer
+    // is enabled, grouping instructions by cycle, then its height is already
+    // covered so only its depth matters. We also reach this point if both stall
+    // but have the same height.
+    if (!SPQ->getHazardRec()->isEnabled()) {
+      if (LHeight != RHeight)
+        return LHeight > RHeight ? 1 : -1;
+    }
+    int LDepth = left->getDepth() - LPenalty;
+    int RDepth = right->getDepth() - RPenalty;
+    if (LDepth != RDepth) {
+      DEBUG(dbgs() << "  Comparing latency of SU (" << left->NodeNum
+            << ") depth " << LDepth << " vs SU (" << right->NodeNum
+            << ") depth " << RDepth << "\n");
+      return LDepth < RDepth ? 1 : -1;
+    }
+    if (left->Latency != right->Latency)
+      return left->Latency > right->Latency ? 1 : -1;
+  }
+  return 0;
+}
+
+static bool BURRSort(SUnit *left, SUnit *right, RegReductionPQBase *SPQ) {
+  // Schedule physical register definitions close to their use. This is
+  // motivated by microarchitectures that can fuse cmp+jump macro-ops. But as
+  // long as shortening physreg live ranges is generally good, we can defer
+  // creating a subtarget hook.
+  if (!DisableSchedPhysRegJoin) {
+    bool LHasPhysReg = left->hasPhysRegDefs;
+    bool RHasPhysReg = right->hasPhysRegDefs;
+    if (LHasPhysReg != RHasPhysReg) {
+      #ifndef NDEBUG
+      static const char *const PhysRegMsg[] = { " has no physreg",
+                                                " defines a physreg" };
+      #endif
+      DEBUG(dbgs() << "  SU (" << left->NodeNum << ") "
+            << PhysRegMsg[LHasPhysReg] << " SU(" << right->NodeNum << ") "
+            << PhysRegMsg[RHasPhysReg] << "\n");
+      return LHasPhysReg < RHasPhysReg;
+    }
+  }
+
+  // Prioritize by Sethi-Ulmann number and push CopyToReg nodes down.
+  unsigned LPriority = SPQ->getNodePriority(left);
+  unsigned RPriority = SPQ->getNodePriority(right);
+
+  // Be really careful about hoisting call operands above previous calls.
+  // Only allows it if it would reduce register pressure.
+  if (left->isCall && right->isCallOp) {
+    unsigned RNumVals = right->getNode()->getNumValues();
+    RPriority = (RPriority > RNumVals) ? (RPriority - RNumVals) : 0;
+  }
+  if (right->isCall && left->isCallOp) {
+    unsigned LNumVals = left->getNode()->getNumValues();
+    LPriority = (LPriority > LNumVals) ? (LPriority - LNumVals) : 0;
+  }
+
+  if (LPriority != RPriority)
+    return LPriority > RPriority;
+
+  // One or both of the nodes are calls and their sethi-ullman numbers are the
+  // same, then keep source order.
+  if (left->isCall || right->isCall) {
+    unsigned LOrder = SPQ->getNodeOrdering(left);
+    unsigned ROrder = SPQ->getNodeOrdering(right);
+
+    // Prefer an ordering where the lower the non-zero order number, the higher
+    // the preference.
+    if ((LOrder || ROrder) && LOrder != ROrder)
+      return LOrder != 0 && (LOrder < ROrder || ROrder == 0);
+  }
+
+  // Try schedule def + use closer when Sethi-Ullman numbers are the same.
+  // e.g.
+  // t1 = op t2, c1
+  // t3 = op t4, c2
+  //
+  // and the following instructions are both ready.
+  // t2 = op c3
+  // t4 = op c4
+  //
+  // Then schedule t2 = op first.
+  // i.e.
+  // t4 = op c4
+  // t2 = op c3
+  // t1 = op t2, c1
+  // t3 = op t4, c2
+  //
+  // This creates more short live intervals.
+  unsigned LDist = closestSucc(left);
+  unsigned RDist = closestSucc(right);
+  if (LDist != RDist)
+    return LDist < RDist;
+
+  // How many registers becomes live when the node is scheduled.
+  unsigned LScratch = calcMaxScratches(left);
+  unsigned RScratch = calcMaxScratches(right);
+  if (LScratch != RScratch)
+    return LScratch > RScratch;
+
+  // Comparing latency against a call makes little sense unless the node
+  // is register pressure-neutral.
+  if ((left->isCall && RPriority > 0) || (right->isCall && LPriority > 0))
+    return (left->NodeQueueId > right->NodeQueueId);
+
+  // Do not compare latencies when one or both of the nodes are calls.
+  if (!DisableSchedCycles &&
+      !(left->isCall || right->isCall)) {
+    int result = BUCompareLatency(left, right, false /*checkPref*/, SPQ);
+    if (result != 0)
+      return result > 0;
+  }
+  else {
+    if (left->getHeight() != right->getHeight())
+      return left->getHeight() > right->getHeight();
+
+    if (left->getDepth() != right->getDepth())
+      return left->getDepth() < right->getDepth();
+  }
+
+  assert(left->NodeQueueId && right->NodeQueueId &&
+         "NodeQueueId cannot be zero");
+  return (left->NodeQueueId > right->NodeQueueId);
+}
+
+// Bottom up
+bool bu_ls_rr_sort::operator()(SUnit *left, SUnit *right) const {
+  if (int res = checkSpecialNodes(left, right))
+    return res > 0;
+
+  return BURRSort(left, right, SPQ);
+}
+
+// Source order, otherwise bottom up.
+bool src_ls_rr_sort::operator()(SUnit *left, SUnit *right) const {
+  if (int res = checkSpecialNodes(left, right))
+    return res > 0;
+
+  unsigned LOrder = SPQ->getNodeOrdering(left);
+  unsigned ROrder = SPQ->getNodeOrdering(right);
+
+  // Prefer an ordering where the lower the non-zero order number, the higher
+  // the preference.
+  if ((LOrder || ROrder) && LOrder != ROrder)
+    return LOrder != 0 && (LOrder < ROrder || ROrder == 0);
+
+  return BURRSort(left, right, SPQ);
+}
+
+// If the time between now and when the instruction will be ready can cover
+// the spill code, then avoid adding it to the ready queue. This gives long
+// stalls highest priority and allows hoisting across calls. It should also
+// speed up processing the available queue.
+bool hybrid_ls_rr_sort::isReady(SUnit *SU, unsigned CurCycle) const {
+  static const unsigned ReadyDelay = 3;
+
+  if (SPQ->MayReduceRegPressure(SU)) return true;
+
+  if (SU->getHeight() > (CurCycle + ReadyDelay)) return false;
+
+  if (SPQ->getHazardRec()->getHazardType(SU, -ReadyDelay)
+      != ScheduleHazardRecognizer::NoHazard)
+    return false;
+
+  return true;
+}
+
+// Return true if right should be scheduled with higher priority than left.
+bool hybrid_ls_rr_sort::operator()(SUnit *left, SUnit *right) const {
+  if (int res = checkSpecialNodes(left, right))
+    return res > 0;
+
+  if (left->isCall || right->isCall)
+    // No way to compute latency of calls.
+    return BURRSort(left, right, SPQ);
+
+  bool LHigh = SPQ->HighRegPressure(left);
+  bool RHigh = SPQ->HighRegPressure(right);
+  // Avoid causing spills. If register pressure is high, schedule for
+  // register pressure reduction.
+  if (LHigh && !RHigh) {
+    DEBUG(dbgs() << "  pressure SU(" << left->NodeNum << ") > SU("
+          << right->NodeNum << ")\n");
+    return true;
+  }
+  else if (!LHigh && RHigh) {
+    DEBUG(dbgs() << "  pressure SU(" << right->NodeNum << ") > SU("
+          << left->NodeNum << ")\n");
+    return false;
+  }
+  if (!LHigh && !RHigh) {
+    int result = BUCompareLatency(left, right, true /*checkPref*/, SPQ);
+    if (result != 0)
+      return result > 0;
+  }
+  return BURRSort(left, right, SPQ);
+}
+
+// Schedule as many instructions in each cycle as possible. So don't make an
+// instruction available unless it is ready in the current cycle.
+bool ilp_ls_rr_sort::isReady(SUnit *SU, unsigned CurCycle) const {
+  if (SU->getHeight() > CurCycle) return false;
+
+  if (SPQ->getHazardRec()->getHazardType(SU, 0)
+      != ScheduleHazardRecognizer::NoHazard)
+    return false;
+
+  return true;
+}
+
+static bool canEnableCoalescing(SUnit *SU) {
+  unsigned Opc = SU->getNode() ? SU->getNode()->getOpcode() : 0;
+  if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
+    // CopyToReg should be close to its uses to facilitate coalescing and
+    // avoid spilling.
+    return true;
+
+  if (Opc == TargetOpcode::EXTRACT_SUBREG ||
+      Opc == TargetOpcode::SUBREG_TO_REG ||
+      Opc == TargetOpcode::INSERT_SUBREG)
+    // EXTRACT_SUBREG, INSERT_SUBREG, and SUBREG_TO_REG nodes should be
+    // close to their uses to facilitate coalescing.
+    return true;
+
+  if (SU->NumPreds == 0 && SU->NumSuccs != 0)
+    // If SU does not have a register def, schedule it close to its uses
+    // because it does not lengthen any live ranges.
+    return true;
+
+  return false;
+}
+
+// list-ilp is currently an experimental scheduler that allows various
+// heuristics to be enabled prior to the normal register reduction logic.
+bool ilp_ls_rr_sort::operator()(SUnit *left, SUnit *right) const {
+  if (int res = checkSpecialNodes(left, right))
+    return res > 0;
+
+  if (left->isCall || right->isCall)
+    // No way to compute latency of calls.
+    return BURRSort(left, right, SPQ);
+
+  unsigned LLiveUses = 0, RLiveUses = 0;
+  int LPDiff = 0, RPDiff = 0;
+  if (!DisableSchedRegPressure || !DisableSchedLiveUses) {
+    LPDiff = SPQ->RegPressureDiff(left, LLiveUses);
+    RPDiff = SPQ->RegPressureDiff(right, RLiveUses);
+  }
+  if (!DisableSchedRegPressure && LPDiff != RPDiff) {
+    DEBUG(dbgs() << "RegPressureDiff SU(" << left->NodeNum << "): " << LPDiff
+          << " != SU(" << right->NodeNum << "): " << RPDiff << "\n");
+    return LPDiff > RPDiff;
+  }
+
+  if (!DisableSchedRegPressure && (LPDiff > 0 || RPDiff > 0)) {
+    bool LReduce = canEnableCoalescing(left);
+    bool RReduce = canEnableCoalescing(right);
+    if (LReduce && !RReduce) return false;
+    if (RReduce && !LReduce) return true;
+  }
+
+  if (!DisableSchedLiveUses && (LLiveUses != RLiveUses)) {
+    DEBUG(dbgs() << "Live uses SU(" << left->NodeNum << "): " << LLiveUses
+          << " != SU(" << right->NodeNum << "): " << RLiveUses << "\n");
+    return LLiveUses < RLiveUses;
+  }
+
+  if (!DisableSchedStalls) {
+    bool LStall = BUHasStall(left, left->getHeight(), SPQ);
+    bool RStall = BUHasStall(right, right->getHeight(), SPQ);
+    if (LStall != RStall)
+      return left->getHeight() > right->getHeight();
+  }
+
+  if (!DisableSchedCriticalPath) {
+    int spread = (int)left->getDepth() - (int)right->getDepth();
+    if (std::abs(spread) > MaxReorderWindow) {
+      DEBUG(dbgs() << "Depth of SU(" << left->NodeNum << "): "
+            << left->getDepth() << " != SU(" << right->NodeNum << "): "
+            << right->getDepth() << "\n");
+      return left->getDepth() < right->getDepth();
+    }
+  }
+
+  if (!DisableSchedHeight && left->getHeight() != right->getHeight()) {
+    int spread = (int)left->getHeight() - (int)right->getHeight();
+    if (std::abs(spread) > MaxReorderWindow)
+      return left->getHeight() > right->getHeight();
+  }
+
+  return BURRSort(left, right, SPQ);
+}
+
+void RegReductionPQBase::initNodes(std::vector<SUnit> &sunits) {
+  SUnits = &sunits;
+  // Add pseudo dependency edges for two-address nodes.
+  if (!Disable2AddrHack)
+    AddPseudoTwoAddrDeps();
+  // Reroute edges to nodes with multiple uses.
+  if (!TracksRegPressure && !SrcOrder)
+    PrescheduleNodesWithMultipleUses();
+  // Calculate node priorities.
+  CalculateSethiUllmanNumbers();
+
+  // For single block loops, mark nodes that look like canonical IV increments.
+  if (scheduleDAG->BB->isSuccessor(scheduleDAG->BB)) {
+    for (unsigned i = 0, e = sunits.size(); i != e; ++i) {
+      initVRegCycle(&sunits[i]);
+    }
+  }
+}
+
+//===----------------------------------------------------------------------===//
+//                    Preschedule for Register Pressure
+//===----------------------------------------------------------------------===//
+
+bool RegReductionPQBase::canClobber(const SUnit *SU, const SUnit *Op) {
+  if (SU->isTwoAddress) {
+    unsigned Opc = SU->getNode()->getMachineOpcode();
+    const MCInstrDesc &MCID = TII->get(Opc);
+    unsigned NumRes = MCID.getNumDefs();
+    unsigned NumOps = MCID.getNumOperands() - NumRes;
+    for (unsigned i = 0; i != NumOps; ++i) {
+      if (MCID.getOperandConstraint(i+NumRes, MCOI::TIED_TO) != -1) {
+        SDNode *DU = SU->getNode()->getOperand(i).getNode();
+        if (DU->getNodeId() != -1 &&
+            Op->OrigNode == &(*SUnits)[DU->getNodeId()])
+          return true;
+      }
+    }
+  }
+  return false;
+}
+
+/// canClobberReachingPhysRegUse - True if SU would clobber one of it's
+/// successor's explicit physregs whose definition can reach DepSU.
+/// i.e. DepSU should not be scheduled above SU.
+static bool canClobberReachingPhysRegUse(const SUnit *DepSU, const SUnit *SU,
+                                         ScheduleDAGRRList *scheduleDAG,
+                                         const TargetInstrInfo *TII,
+                                         const TargetRegisterInfo *TRI) {
+  const uint16_t *ImpDefs
+    = TII->get(SU->getNode()->getMachineOpcode()).getImplicitDefs();
+  const uint32_t *RegMask = getNodeRegMask(SU->getNode());
+  if(!ImpDefs && !RegMask)
+    return false;
+
+  for (SUnit::const_succ_iterator SI = SU->Succs.begin(), SE = SU->Succs.end();
+       SI != SE; ++SI) {
+    SUnit *SuccSU = SI->getSUnit();
+    for (SUnit::const_pred_iterator PI = SuccSU->Preds.begin(),
+           PE = SuccSU->Preds.end(); PI != PE; ++PI) {
+      if (!PI->isAssignedRegDep())
+        continue;
+
+      if (RegMask && MachineOperand::clobbersPhysReg(RegMask, PI->getReg()) &&
+          scheduleDAG->IsReachable(DepSU, PI->getSUnit()))
+        return true;
+
+      if (ImpDefs)
+        for (const uint16_t *ImpDef = ImpDefs; *ImpDef; ++ImpDef)
+          // Return true if SU clobbers this physical register use and the
+          // definition of the register reaches from DepSU. IsReachable queries
+          // a topological forward sort of the DAG (following the successors).
+          if (TRI->regsOverlap(*ImpDef, PI->getReg()) &&
+              scheduleDAG->IsReachable(DepSU, PI->getSUnit()))
+            return true;
+    }
+  }
+  return false;
+}
+
+/// canClobberPhysRegDefs - True if SU would clobber one of SuccSU's
+/// physical register defs.
+static bool canClobberPhysRegDefs(const SUnit *SuccSU, const SUnit *SU,
+                                  const TargetInstrInfo *TII,
+                                  const TargetRegisterInfo *TRI) {
+  SDNode *N = SuccSU->getNode();
+  unsigned NumDefs = TII->get(N->getMachineOpcode()).getNumDefs();
+  const uint16_t *ImpDefs = TII->get(N->getMachineOpcode()).getImplicitDefs();
+  assert(ImpDefs && "Caller should check hasPhysRegDefs");
+  for (const SDNode *SUNode = SU->getNode(); SUNode;
+       SUNode = SUNode->getGluedNode()) {
+    if (!SUNode->isMachineOpcode())
+      continue;
+    const uint16_t *SUImpDefs =
+      TII->get(SUNode->getMachineOpcode()).getImplicitDefs();
+    const uint32_t *SURegMask = getNodeRegMask(SUNode);
+    if (!SUImpDefs && !SURegMask)
+      continue;
+    for (unsigned i = NumDefs, e = N->getNumValues(); i != e; ++i) {
+      EVT VT = N->getValueType(i);
+      if (VT == MVT::Glue || VT == MVT::Other)
+        continue;
+      if (!N->hasAnyUseOfValue(i))
+        continue;
+      unsigned Reg = ImpDefs[i - NumDefs];
+      if (SURegMask && MachineOperand::clobbersPhysReg(SURegMask, Reg))
+        return true;
+      if (!SUImpDefs)
+        continue;
+      for (;*SUImpDefs; ++SUImpDefs) {
+        unsigned SUReg = *SUImpDefs;
+        if (TRI->regsOverlap(Reg, SUReg))
+          return true;
+      }
+    }
+  }
+  return false;
+}
+
+/// PrescheduleNodesWithMultipleUses - Nodes with multiple uses
+/// are not handled well by the general register pressure reduction
+/// heuristics. When presented with code like this:
+///
+///      N
+///    / |
+///   /  |
+///  U  store
+///  |
+/// ...
+///
+/// the heuristics tend to push the store up, but since the
+/// operand of the store has another use (U), this would increase
+/// the length of that other use (the U->N edge).
+///
+/// This function transforms code like the above to route U's
+/// dependence through the store when possible, like this:
+///
+///      N
+///      ||
+///      ||
+///     store
+///       |
+///       U
+///       |
+///      ...
+///
+/// This results in the store being scheduled immediately
+/// after N, which shortens the U->N live range, reducing
+/// register pressure.
+///
+void RegReductionPQBase::PrescheduleNodesWithMultipleUses() {
+  // Visit all the nodes in topological order, working top-down.
+  for (unsigned i = 0, e = SUnits->size(); i != e; ++i) {
+    SUnit *SU = &(*SUnits)[i];
+    // For now, only look at nodes with no data successors, such as stores.
+    // These are especially important, due to the heuristics in
+    // getNodePriority for nodes with no data successors.
+    if (SU->NumSuccs != 0)
+      continue;
+    // For now, only look at nodes with exactly one data predecessor.
+    if (SU->NumPreds != 1)
+      continue;
+    // Avoid prescheduling copies to virtual registers, which don't behave
+    // like other nodes from the perspective of scheduling heuristics.
+    if (SDNode *N = SU->getNode())
+      if (N->getOpcode() == ISD::CopyToReg &&
+          TargetRegisterInfo::isVirtualRegister
+            (cast<RegisterSDNode>(N->getOperand(1))->getReg()))
+        continue;
+
+    // Locate the single data predecessor.
+    SUnit *PredSU = 0;
+    for (SUnit::const_pred_iterator II = SU->Preds.begin(),
+         EE = SU->Preds.end(); II != EE; ++II)
+      if (!II->isCtrl()) {
+        PredSU = II->getSUnit();
+        break;
+      }
+    assert(PredSU);
+
+    // Don't rewrite edges that carry physregs, because that requires additional
+    // support infrastructure.
+    if (PredSU->hasPhysRegDefs)
+      continue;
+    // Short-circuit the case where SU is PredSU's only data successor.
+    if (PredSU->NumSuccs == 1)
+      continue;
+    // Avoid prescheduling to copies from virtual registers, which don't behave
+    // like other nodes from the perspective of scheduling heuristics.
+    if (SDNode *N = SU->getNode())
+      if (N->getOpcode() == ISD::CopyFromReg &&
+          TargetRegisterInfo::isVirtualRegister
+            (cast<RegisterSDNode>(N->getOperand(1))->getReg()))
+        continue;
+
+    // Perform checks on the successors of PredSU.
+    for (SUnit::const_succ_iterator II = PredSU->Succs.begin(),
+         EE = PredSU->Succs.end(); II != EE; ++II) {
+      SUnit *PredSuccSU = II->getSUnit();
+      if (PredSuccSU == SU) continue;
+      // If PredSU has another successor with no data successors, for
+      // now don't attempt to choose either over the other.
+      if (PredSuccSU->NumSuccs == 0)
+        goto outer_loop_continue;
+      // Don't break physical register dependencies.
+      if (SU->hasPhysRegClobbers && PredSuccSU->hasPhysRegDefs)
+        if (canClobberPhysRegDefs(PredSuccSU, SU, TII, TRI))
+          goto outer_loop_continue;
+      // Don't introduce graph cycles.
+      if (scheduleDAG->IsReachable(SU, PredSuccSU))
+        goto outer_loop_continue;
+    }
+
+    // Ok, the transformation is safe and the heuristics suggest it is
+    // profitable. Update the graph.
+    DEBUG(dbgs() << "    Prescheduling SU #" << SU->NodeNum
+                 << " next to PredSU #" << PredSU->NodeNum
+                 << " to guide scheduling in the presence of multiple uses\n");
+    for (unsigned i = 0; i != PredSU->Succs.size(); ++i) {
+      SDep Edge = PredSU->Succs[i];
+      assert(!Edge.isAssignedRegDep());
+      SUnit *SuccSU = Edge.getSUnit();
+      if (SuccSU != SU) {
+        Edge.setSUnit(PredSU);
+        scheduleDAG->RemovePred(SuccSU, Edge);
+        scheduleDAG->AddPred(SU, Edge);
+        Edge.setSUnit(SU);
+        scheduleDAG->AddPred(SuccSU, Edge);
+        --i;
+      }
+    }
+  outer_loop_continue:;
+  }
+}
+
+/// AddPseudoTwoAddrDeps - If two nodes share an operand and one of them uses
+/// it as a def&use operand. Add a pseudo control edge from it to the other
+/// node (if it won't create a cycle) so the two-address one will be scheduled
+/// first (lower in the schedule). If both nodes are two-address, favor the
+/// one that has a CopyToReg use (more likely to be a loop induction update).
+/// If both are two-address, but one is commutable while the other is not
+/// commutable, favor the one that's not commutable.
+void RegReductionPQBase::AddPseudoTwoAddrDeps() {
+  for (unsigned i = 0, e = SUnits->size(); i != e; ++i) {
+    SUnit *SU = &(*SUnits)[i];
+    if (!SU->isTwoAddress)
+      continue;
+
+    SDNode *Node = SU->getNode();
+    if (!Node || !Node->isMachineOpcode() || SU->getNode()->getGluedNode())
+      continue;
+
+    bool isLiveOut = hasOnlyLiveOutUses(SU);
+    unsigned Opc = Node->getMachineOpcode();
+    const MCInstrDesc &MCID = TII->get(Opc);
+    unsigned NumRes = MCID.getNumDefs();
+    unsigned NumOps = MCID.getNumOperands() - NumRes;
+    for (unsigned j = 0; j != NumOps; ++j) {
+      if (MCID.getOperandConstraint(j+NumRes, MCOI::TIED_TO) == -1)
+        continue;
+      SDNode *DU = SU->getNode()->getOperand(j).getNode();
+      if (DU->getNodeId() == -1)
+        continue;
+      const SUnit *DUSU = &(*SUnits)[DU->getNodeId()];
+      if (!DUSU) continue;
+      for (SUnit::const_succ_iterator I = DUSU->Succs.begin(),
+           E = DUSU->Succs.end(); I != E; ++I) {
+        if (I->isCtrl()) continue;
+        SUnit *SuccSU = I->getSUnit();
+        if (SuccSU == SU)
+          continue;
+        // Be conservative. Ignore if nodes aren't at roughly the same
+        // depth and height.
+        if (SuccSU->getHeight() < SU->getHeight() &&
+            (SU->getHeight() - SuccSU->getHeight()) > 1)
+          continue;
+        // Skip past COPY_TO_REGCLASS nodes, so that the pseudo edge
+        // constrains whatever is using the copy, instead of the copy
+        // itself. In the case that the copy is coalesced, this
+        // preserves the intent of the pseudo two-address heurietics.
+        while (SuccSU->Succs.size() == 1 &&
+               SuccSU->getNode()->isMachineOpcode() &&
+               SuccSU->getNode()->getMachineOpcode() ==
+                 TargetOpcode::COPY_TO_REGCLASS)
+          SuccSU = SuccSU->Succs.front().getSUnit();
+        // Don't constrain non-instruction nodes.
+        if (!SuccSU->getNode() || !SuccSU->getNode()->isMachineOpcode())
+          continue;
+        // Don't constrain nodes with physical register defs if the
+        // predecessor can clobber them.
+        if (SuccSU->hasPhysRegDefs && SU->hasPhysRegClobbers) {
+          if (canClobberPhysRegDefs(SuccSU, SU, TII, TRI))
+            continue;
+        }
+        // Don't constrain EXTRACT_SUBREG, INSERT_SUBREG, and SUBREG_TO_REG;
+        // these may be coalesced away. We want them close to their uses.
+        unsigned SuccOpc = SuccSU->getNode()->getMachineOpcode();
+        if (SuccOpc == TargetOpcode::EXTRACT_SUBREG ||
+            SuccOpc == TargetOpcode::INSERT_SUBREG ||
+            SuccOpc == TargetOpcode::SUBREG_TO_REG)
+          continue;
+        if (!canClobberReachingPhysRegUse(SuccSU, SU, scheduleDAG, TII, TRI) &&
+            (!canClobber(SuccSU, DUSU) ||
+             (isLiveOut && !hasOnlyLiveOutUses(SuccSU)) ||
+             (!SU->isCommutable && SuccSU->isCommutable)) &&
+            !scheduleDAG->IsReachable(SuccSU, SU)) {
+          DEBUG(dbgs() << "    Adding a pseudo-two-addr edge from SU #"
+                       << SU->NodeNum << " to SU #" << SuccSU->NodeNum << "\n");
+          scheduleDAG->AddPred(SU, SDep(SuccSU, SDep::Artificial));
+        }
+      }
+    }
+  }
+}
+
+//===----------------------------------------------------------------------===//
+//                         Public Constructor Functions
+//===----------------------------------------------------------------------===//
+
+llvm::ScheduleDAGSDNodes *
+llvm::createBURRListDAGScheduler(SelectionDAGISel *IS,
+                                 CodeGenOpt::Level OptLevel) {
+  const TargetMachine &TM = IS->TM;
+  const TargetInstrInfo *TII = TM.getInstrInfo();
+  const TargetRegisterInfo *TRI = TM.getRegisterInfo();
+
+  BURegReductionPriorityQueue *PQ =
+    new BURegReductionPriorityQueue(*IS->MF, false, false, TII, TRI, 0);
+  ScheduleDAGRRList *SD = new ScheduleDAGRRList(*IS->MF, false, PQ, OptLevel);
+  PQ->setScheduleDAG(SD);
+  return SD;
+}
+
+llvm::ScheduleDAGSDNodes *
+llvm::createSourceListDAGScheduler(SelectionDAGISel *IS,
+                                   CodeGenOpt::Level OptLevel) {
+  const TargetMachine &TM = IS->TM;
+  const TargetInstrInfo *TII = TM.getInstrInfo();
+  const TargetRegisterInfo *TRI = TM.getRegisterInfo();
+
+  SrcRegReductionPriorityQueue *PQ =
+    new SrcRegReductionPriorityQueue(*IS->MF, false, true, TII, TRI, 0);
+  ScheduleDAGRRList *SD = new ScheduleDAGRRList(*IS->MF, false, PQ, OptLevel);
+  PQ->setScheduleDAG(SD);
+  return SD;
+}
+
+llvm::ScheduleDAGSDNodes *
+llvm::createHybridListDAGScheduler(SelectionDAGISel *IS,
+                                   CodeGenOpt::Level OptLevel) {
+  const TargetMachine &TM = IS->TM;
+  const TargetInstrInfo *TII = TM.getInstrInfo();
+  const TargetRegisterInfo *TRI = TM.getRegisterInfo();
+  const TargetLowering *TLI = IS->getTargetLowering();
+
+  HybridBURRPriorityQueue *PQ =
+    new HybridBURRPriorityQueue(*IS->MF, true, false, TII, TRI, TLI);
+
+  ScheduleDAGRRList *SD = new ScheduleDAGRRList(*IS->MF, true, PQ, OptLevel);
+  PQ->setScheduleDAG(SD);
+  return SD;
+}
+
+llvm::ScheduleDAGSDNodes *
+llvm::createILPListDAGScheduler(SelectionDAGISel *IS,
+                                CodeGenOpt::Level OptLevel) {
+  const TargetMachine &TM = IS->TM;
+  const TargetInstrInfo *TII = TM.getInstrInfo();
+  const TargetRegisterInfo *TRI = TM.getRegisterInfo();
+  const TargetLowering *TLI = IS->getTargetLowering();
+
+  ILPBURRPriorityQueue *PQ =
+    new ILPBURRPriorityQueue(*IS->MF, true, false, TII, TRI, TLI);
+  ScheduleDAGRRList *SD = new ScheduleDAGRRList(*IS->MF, true, PQ, OptLevel);
+  PQ->setScheduleDAG(SD);
+  return SD;
+}