Reorganization: Move the Spiller out of VirtRegMap.cpp into its own files. No (intended) functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66720 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 2 insertions, 1873 deletions

diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp
index 0e00f78..0bfbded 100644
--- a/lib/CodeGen/VirtRegMap.cpp
+++ b/lib/CodeGen/VirtRegMap.cpp
@@ -16,7 +16,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#define DEBUG_TYPE "spiller"
+#define DEBUG_TYPE "virtregmap"
 #include "VirtRegMap.h"
 #include "llvm/Function.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
@@ -38,31 +38,6 @@
 using namespace llvm;
 
 STATISTIC(NumSpills  , "Number of register spills");
-STATISTIC(NumPSpills , "Number of physical register spills");
-STATISTIC(NumReMats  , "Number of re-materialization");
-STATISTIC(NumDRM     , "Number of re-materializable defs elided");
-STATISTIC(NumStores  , "Number of stores added");
-STATISTIC(NumLoads   , "Number of loads added");
-STATISTIC(NumReused  , "Number of values reused");
-STATISTIC(NumDSE     , "Number of dead stores elided");
-STATISTIC(NumDCE     , "Number of copies elided");
-STATISTIC(NumDSS     , "Number of dead spill slots removed");
-STATISTIC(NumCommutes, "Number of instructions commuted");
-STATISTIC(NumOmitted , "Number of reloads omited");
-STATISTIC(NumCopified, "Number of available reloads turned into copies");
-
-namespace {
-  enum SpillerName { simple, local };
-}
-
-static cl::opt<SpillerName>
-SpillerOpt("spiller",
-           cl::desc("Spiller to use: (default: local)"),
-           cl::Prefix,
-           cl::values(clEnumVal(simple, "simple spiller"),
-                      clEnumVal(local,  "local spiller"),
-                      clEnumValEnd),
-           cl::init(local));
 
 //===----------------------------------------------------------------------===//
 //  VirtRegMap implementation
@@ -224,1850 +199,4 @@ void VirtRegMap::print(std::ostream &OS) const {
 
 void VirtRegMap::dump() const {
   print(cerr);
-}
-
-
-//===----------------------------------------------------------------------===//
-// Simple Spiller Implementation
-//===----------------------------------------------------------------------===//
-
-Spiller::~Spiller() {}
-
-namespace {
-  struct VISIBILITY_HIDDEN SimpleSpiller : public Spiller {
-    bool runOnMachineFunction(MachineFunction& mf, VirtRegMap &VRM);
-  };
-}
-
-bool SimpleSpiller::runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
-  DOUT << "********** REWRITE MACHINE CODE **********\n";
-  DOUT << "********** Function: " << MF.getFunction()->getName() << '\n';
-  const TargetMachine &TM = MF.getTarget();
-  const TargetInstrInfo &TII = *TM.getInstrInfo();
-  const TargetRegisterInfo &TRI = *TM.getRegisterInfo();
-  
-
-  // LoadedRegs - Keep track of which vregs are loaded, so that we only load
-  // each vreg once (in the case where a spilled vreg is used by multiple
-  // operands).  This is always smaller than the number of operands to the
-  // current machine instr, so it should be small.
-  std::vector<unsigned> LoadedRegs;
-
-  for (MachineFunction::iterator MBBI = MF.begin(), E = MF.end();
-       MBBI != E; ++MBBI) {
-    DOUT << MBBI->getBasicBlock()->getName() << ":\n";
-    MachineBasicBlock &MBB = *MBBI;
-    for (MachineBasicBlock::iterator MII = MBB.begin(),
-           E = MBB.end(); MII != E; ++MII) {
-      MachineInstr &MI = *MII;
-      for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
-        MachineOperand &MO = MI.getOperand(i);
-        if (MO.isReg() && MO.getReg()) {
-          if (TargetRegisterInfo::isVirtualRegister(MO.getReg())) {
-            unsigned VirtReg = MO.getReg();
-            unsigned SubIdx = MO.getSubReg();
-            unsigned PhysReg = VRM.getPhys(VirtReg);
-            unsigned RReg = SubIdx ? TRI.getSubReg(PhysReg, SubIdx) : PhysReg;
-            if (!VRM.isAssignedReg(VirtReg)) {
-              int StackSlot = VRM.getStackSlot(VirtReg);
-              const TargetRegisterClass* RC =
-                MF.getRegInfo().getRegClass(VirtReg);
-
-              if (MO.isUse() &&
-                  std::find(LoadedRegs.begin(), LoadedRegs.end(), VirtReg)
-                  == LoadedRegs.end()) {
-                TII.loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC);
-                MachineInstr *LoadMI = prior(MII);
-                VRM.addSpillSlotUse(StackSlot, LoadMI);
-                LoadedRegs.push_back(VirtReg);
-                ++NumLoads;
-                DOUT << '\t' << *LoadMI;
-              }
-
-              if (MO.isDef()) {
-                TII.storeRegToStackSlot(MBB, next(MII), PhysReg, true,
-                                        StackSlot, RC);
-                MachineInstr *StoreMI = next(MII);
-                VRM.addSpillSlotUse(StackSlot, StoreMI);
-                ++NumStores;
-              }
-            }
-            MF.getRegInfo().setPhysRegUsed(RReg);
-            MI.getOperand(i).setReg(RReg);
-          } else {
-            MF.getRegInfo().setPhysRegUsed(MO.getReg());
-          }
-        }
-      }
-
-      DOUT << '\t' << MI;
-      LoadedRegs.clear();
-    }
-  }
-  return true;
-}
-
-//===----------------------------------------------------------------------===//
-//  Local Spiller Implementation
-//===----------------------------------------------------------------------===//
-
-/// AvailableSpills - As the local spiller is scanning and rewriting an MBB from
-/// top down, keep track of which spills slots or remat are available in each
-/// register.
-///
-/// Note that not all physregs are created equal here.  In particular, some
-/// physregs are reloads that we are allowed to clobber or ignore at any time.
-/// Other physregs are values that the register allocated program is using that
-/// we cannot CHANGE, but we can read if we like.  We keep track of this on a 
-/// per-stack-slot / remat id basis as the low bit in the value of the
-/// SpillSlotsAvailable entries.  The predicate 'canClobberPhysReg()' checks
-/// this bit and addAvailable sets it if.
-namespace {
-class VISIBILITY_HIDDEN AvailableSpills {
-  const TargetRegisterInfo *TRI;
-  const TargetInstrInfo *TII;
-
-  // SpillSlotsOrReMatsAvailable - This map keeps track of all of the spilled
-  // or remat'ed virtual register values that are still available, due to being
-  // loaded or stored to, but not invalidated yet.
-  std::map<int, unsigned> SpillSlotsOrReMatsAvailable;
-    
-  // PhysRegsAvailable - This is the inverse of SpillSlotsOrReMatsAvailable,
-  // indicating which stack slot values are currently held by a physreg.  This
-  // is used to invalidate entries in SpillSlotsOrReMatsAvailable when a
-  // physreg is modified.
-  std::multimap<unsigned, int> PhysRegsAvailable;
-  
-  void disallowClobberPhysRegOnly(unsigned PhysReg);
-
-  void ClobberPhysRegOnly(unsigned PhysReg);
-public:
-  AvailableSpills(const TargetRegisterInfo *tri, const TargetInstrInfo *tii)
-    : TRI(tri), TII(tii) {
-  }
-
-  /// clear - Reset the state.
-  void clear() {
-    SpillSlotsOrReMatsAvailable.clear();
-    PhysRegsAvailable.clear();
-  }
-  
-  const TargetRegisterInfo *getRegInfo() const { return TRI; }
-
-  /// getSpillSlotOrReMatPhysReg - If the specified stack slot or remat is
-  /// available in a  physical register, return that PhysReg, otherwise
-  /// return 0.
-  unsigned getSpillSlotOrReMatPhysReg(int Slot) const {
-    std::map<int, unsigned>::const_iterator I =
-      SpillSlotsOrReMatsAvailable.find(Slot);
-    if (I != SpillSlotsOrReMatsAvailable.end()) {
-      return I->second >> 1;  // Remove the CanClobber bit.
-    }
-    return 0;
-  }
-
-  /// addAvailable - Mark that the specified stack slot / remat is available in
-  /// the specified physreg.  If CanClobber is true, the physreg can be modified
-  /// at any time without changing the semantics of the program.
-  void addAvailable(int SlotOrReMat, unsigned Reg, bool CanClobber = true) {
-    // If this stack slot is thought to be available in some other physreg, 
-    // remove its record.
-    ModifyStackSlotOrReMat(SlotOrReMat);
-    
-    PhysRegsAvailable.insert(std::make_pair(Reg, SlotOrReMat));
-    SpillSlotsOrReMatsAvailable[SlotOrReMat]= (Reg << 1) | (unsigned)CanClobber;
-  
-    if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT)
-      DOUT << "Remembering RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1;
-    else
-      DOUT << "Remembering SS#" << SlotOrReMat;
-    DOUT << " in physreg " << TRI->getName(Reg) << "\n";
-  }
-
-  /// canClobberPhysReg - Return true if the spiller is allowed to change the 
-  /// value of the specified stackslot register if it desires.  The specified
-  /// stack slot must be available in a physreg for this query to make sense.
-  bool canClobberPhysReg(int SlotOrReMat) const {
-    assert(SpillSlotsOrReMatsAvailable.count(SlotOrReMat) &&
-           "Value not available!");
-    return SpillSlotsOrReMatsAvailable.find(SlotOrReMat)->second & 1;
-  }
-
-  /// disallowClobberPhysReg - Unset the CanClobber bit of the specified
-  /// stackslot register. The register is still available but is no longer
-  /// allowed to be modifed.
-  void disallowClobberPhysReg(unsigned PhysReg);
-  
-  /// ClobberPhysReg - This is called when the specified physreg changes
-  /// value.  We use this to invalidate any info about stuff that lives in
-  /// it and any of its aliases.
-  void ClobberPhysReg(unsigned PhysReg);
-
-  /// ModifyStackSlotOrReMat - This method is called when the value in a stack
-  /// slot changes.  This removes information about which register the previous
-  /// value for this slot lives in (as the previous value is dead now).
-  void ModifyStackSlotOrReMat(int SlotOrReMat);
-
-  /// AddAvailableRegsToLiveIn - Availability information is being kept coming
-  /// into the specified MBB. Add available physical registers as potential
-  /// live-in's. If they are reused in the MBB, they will be added to the
-  /// live-in set to make register scavenger and post-allocation scheduler.
-  void AddAvailableRegsToLiveIn(MachineBasicBlock &MBB, BitVector &RegKills,
-                                std::vector<MachineOperand*> &KillOps);
-};
-}
-
-/// disallowClobberPhysRegOnly - Unset the CanClobber bit of the specified
-/// stackslot register. The register is still available but is no longer
-/// allowed to be modifed.
-void AvailableSpills::disallowClobberPhysRegOnly(unsigned PhysReg) {
-  std::multimap<unsigned, int>::iterator I =
-    PhysRegsAvailable.lower_bound(PhysReg);
-  while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
-    int SlotOrReMat = I->second;
-    I++;
-    assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg &&
-           "Bidirectional map mismatch!");
-    SpillSlotsOrReMatsAvailable[SlotOrReMat] &= ~1;
-    DOUT << "PhysReg " << TRI->getName(PhysReg)
-         << " copied, it is available for use but can no longer be modified\n";
-  }
-}
-
-/// disallowClobberPhysReg - Unset the CanClobber bit of the specified
-/// stackslot register and its aliases. The register and its aliases may
-/// still available but is no longer allowed to be modifed.
-void AvailableSpills::disallowClobberPhysReg(unsigned PhysReg) {
-  for (const unsigned *AS = TRI->getAliasSet(PhysReg); *AS; ++AS)
-    disallowClobberPhysRegOnly(*AS);
-  disallowClobberPhysRegOnly(PhysReg);
-}
-
-/// ClobberPhysRegOnly - This is called when the specified physreg changes
-/// value.  We use this to invalidate any info about stuff we thing lives in it.
-void AvailableSpills::ClobberPhysRegOnly(unsigned PhysReg) {
-  std::multimap<unsigned, int>::iterator I =
-    PhysRegsAvailable.lower_bound(PhysReg);
-  while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
-    int SlotOrReMat = I->second;
-    PhysRegsAvailable.erase(I++);
-    assert((SpillSlotsOrReMatsAvailable[SlotOrReMat] >> 1) == PhysReg &&
-           "Bidirectional map mismatch!");
-    SpillSlotsOrReMatsAvailable.erase(SlotOrReMat);
-    DOUT << "PhysReg " << TRI->getName(PhysReg)
-         << " clobbered, invalidating ";
-    if (SlotOrReMat > VirtRegMap::MAX_STACK_SLOT)
-      DOUT << "RM#" << SlotOrReMat-VirtRegMap::MAX_STACK_SLOT-1 << "\n";
-    else
-      DOUT << "SS#" << SlotOrReMat << "\n";
-  }
-}
-
-/// ClobberPhysReg - This is called when the specified physreg changes
-/// value.  We use this to invalidate any info about stuff we thing lives in
-/// it and any of its aliases.
-void AvailableSpills::ClobberPhysReg(unsigned PhysReg) {
-  for (const unsigned *AS = TRI->getAliasSet(PhysReg); *AS; ++AS)
-    ClobberPhysRegOnly(*AS);
-  ClobberPhysRegOnly(PhysReg);
-}
-
-/// ModifyStackSlotOrReMat - This method is called when the value in a stack
-/// slot changes.  This removes information about which register the previous
-/// value for this slot lives in (as the previous value is dead now).
-void AvailableSpills::ModifyStackSlotOrReMat(int SlotOrReMat) {
-  std::map<int, unsigned>::iterator It =
-    SpillSlotsOrReMatsAvailable.find(SlotOrReMat);
-  if (It == SpillSlotsOrReMatsAvailable.end()) return;
-  unsigned Reg = It->second >> 1;
-  SpillSlotsOrReMatsAvailable.erase(It);
-  
-  // This register may hold the value of multiple stack slots, only remove this
-  // stack slot from the set of values the register contains.
-  std::multimap<unsigned, int>::iterator I = PhysRegsAvailable.lower_bound(Reg);
-  for (; ; ++I) {
-    assert(I != PhysRegsAvailable.end() && I->first == Reg &&
-           "Map inverse broken!");
-    if (I->second == SlotOrReMat) break;
-  }
-  PhysRegsAvailable.erase(I);
-}
-
-/// InvalidateKill - A MI that defines the specified register is being deleted,
-/// invalidate the register kill information.
-static void InvalidateKill(unsigned Reg, BitVector &RegKills,
-                           std::vector<MachineOperand*> &KillOps) {
-  if (RegKills[Reg]) {
-    KillOps[Reg]->setIsKill(false);
-    KillOps[Reg] = NULL;
-    RegKills.reset(Reg);
-  }
-}
-
-/// AddAvailableRegsToLiveIn - Availability information is being kept coming
-/// into the specified MBB. Add available physical registers as potential
-/// live-in's. If they are reused in the MBB, they will be added to the
-/// live-in set to make register scavenger and post-allocation scheduler.
-void AvailableSpills::AddAvailableRegsToLiveIn(MachineBasicBlock &MBB,
-                                        BitVector &RegKills,
-                                        std::vector<MachineOperand*> &KillOps) {
-  std::set<unsigned> NotAvailable;
-  for (std::multimap<unsigned, int>::iterator
-         I = PhysRegsAvailable.begin(), E = PhysRegsAvailable.end();
-       I != E; ++I) {
-    unsigned Reg = I->first;
-    const TargetRegisterClass* RC = TRI->getPhysicalRegisterRegClass(Reg);
-    // FIXME: A temporary workaround. We can't reuse available value if it's
-    // not safe to move the def of the virtual register's class. e.g.
-    // X86::RFP* register classes. Do not add it as a live-in.
-    if (!TII->isSafeToMoveRegClassDefs(RC))
-      // This is no longer available.
-      NotAvailable.insert(Reg);
-    else {
-      MBB.addLiveIn(Reg);
-      InvalidateKill(Reg, RegKills, KillOps);
-    }
-
-    // Skip over the same register.
-    std::multimap<unsigned, int>::iterator NI = next(I);
-    while (NI != E && NI->first == Reg) {
-      ++I;
-      ++NI;
-    }
-  }
-
-  for (std::set<unsigned>::iterator I = NotAvailable.begin(),
-         E = NotAvailable.end(); I != E; ++I) {
-    ClobberPhysReg(*I);
-    for (const unsigned *SubRegs = TRI->getSubRegisters(*I);
-       *SubRegs; ++SubRegs)
-      ClobberPhysReg(*SubRegs);
-  }
-}
-
-/// findSinglePredSuccessor - Return via reference a vector of machine basic
-/// blocks each of which is a successor of the specified BB and has no other
-/// predecessor.
-static void findSinglePredSuccessor(MachineBasicBlock *MBB,
-                                   SmallVectorImpl<MachineBasicBlock *> &Succs) {
-  for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
-         SE = MBB->succ_end(); SI != SE; ++SI) {
-    MachineBasicBlock *SuccMBB = *SI;
-    if (SuccMBB->pred_size() == 1)
-      Succs.push_back(SuccMBB);
-  }
-}
-
-namespace {
-  /// LocalSpiller - This spiller does a simple pass over the machine basic
-  /// block to attempt to keep spills in registers as much as possible for
-  /// blocks that have low register pressure (the vreg may be spilled due to
-  /// register pressure in other blocks).
-  class VISIBILITY_HIDDEN LocalSpiller : public Spiller {
-    MachineRegisterInfo *RegInfo;
-    const TargetRegisterInfo *TRI;
-    const TargetInstrInfo *TII;
-    DenseMap<MachineInstr*, unsigned> DistanceMap;
-  public:
-    bool runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
-      RegInfo = &MF.getRegInfo(); 
-      TRI = MF.getTarget().getRegisterInfo();
-      TII = MF.getTarget().getInstrInfo();
-      DOUT << "\n**** Local spiller rewriting function '"
-           << MF.getFunction()->getName() << "':\n";
-      DOUT << "**** Machine Instrs (NOTE! Does not include spills and reloads!)"
-              " ****\n";
-      DEBUG(MF.dump());
-
-      // Spills - Keep track of which spilled values are available in physregs
-      // so that we can choose to reuse the physregs instead of emitting
-      // reloads. This is usually refreshed per basic block.
-      AvailableSpills Spills(TRI, TII);
-
-      // Keep track of kill information.
-      BitVector RegKills(TRI->getNumRegs());
-      std::vector<MachineOperand*> KillOps;
-      KillOps.resize(TRI->getNumRegs(), NULL);
-
-      // SingleEntrySuccs - Successor blocks which have a single predecessor.
-      SmallVector<MachineBasicBlock*, 4> SinglePredSuccs;
-      SmallPtrSet<MachineBasicBlock*,16> EarlyVisited;
-
-      // Traverse the basic blocks depth first.
-      MachineBasicBlock *Entry = MF.begin();
-      SmallPtrSet<MachineBasicBlock*,16> Visited;
-      for (df_ext_iterator<MachineBasicBlock*,
-             SmallPtrSet<MachineBasicBlock*,16> >
-             DFI = df_ext_begin(Entry, Visited), E = df_ext_end(Entry, Visited);
-           DFI != E; ++DFI) {
-        MachineBasicBlock *MBB = *DFI;
-        if (!EarlyVisited.count(MBB))
-          RewriteMBB(*MBB, VRM, Spills, RegKills, KillOps);
-
-        // If this MBB is the only predecessor of a successor. Keep the
-        // availability information and visit it next.
-        do {
-          // Keep visiting single predecessor successor as long as possible.
-          SinglePredSuccs.clear();
-          findSinglePredSuccessor(MBB, SinglePredSuccs);
-          if (SinglePredSuccs.empty())
-            MBB = 0;
-          else {
-            // FIXME: More than one successors, each of which has MBB has
-            // the only predecessor.
-            MBB = SinglePredSuccs[0];
-            if (!Visited.count(MBB) && EarlyVisited.insert(MBB)) {
-              Spills.AddAvailableRegsToLiveIn(*MBB, RegKills, KillOps);
-              RewriteMBB(*MBB, VRM, Spills, RegKills, KillOps);
-            }
-          }
-        } while (MBB);
-
-        // Clear the availability info.
-        Spills.clear();
-      }
-
-      DOUT << "**** Post Machine Instrs ****\n";
-      DEBUG(MF.dump());
-
-      // Mark unused spill slots.
-      MachineFrameInfo *MFI = MF.getFrameInfo();
-      int SS = VRM.getLowSpillSlot();
-      if (SS != VirtRegMap::NO_STACK_SLOT)
-        for (int e = VRM.getHighSpillSlot(); SS <= e; ++SS)
-          if (!VRM.isSpillSlotUsed(SS)) {
-            MFI->RemoveStackObject(SS);
-            ++NumDSS;
-          }
-
-      return true;
-    }
-  private:
-    void TransferDeadness(MachineBasicBlock *MBB, unsigned CurDist,
-                          unsigned Reg, BitVector &RegKills,
-                          std::vector<MachineOperand*> &KillOps);
-    bool PrepForUnfoldOpti(MachineBasicBlock &MBB,
-                           MachineBasicBlock::iterator &MII,
-                           std::vector<MachineInstr*> &MaybeDeadStores,
-                           AvailableSpills &Spills, BitVector &RegKills,
-                           std::vector<MachineOperand*> &KillOps,
-                           VirtRegMap &VRM);
-    bool CommuteToFoldReload(MachineBasicBlock &MBB,
-                             MachineBasicBlock::iterator &MII,
-                             unsigned VirtReg, unsigned SrcReg, int SS,
-                             AvailableSpills &Spills,
-                             BitVector &RegKills,
-                             std::vector<MachineOperand*> &KillOps,
-                             const TargetRegisterInfo *TRI,
-                             VirtRegMap &VRM);
-    void SpillRegToStackSlot(MachineBasicBlock &MBB,
-                             MachineBasicBlock::iterator &MII,
-                             int Idx, unsigned PhysReg, int StackSlot,
-                             const TargetRegisterClass *RC,
-                             bool isAvailable, MachineInstr *&LastStore,
-                             AvailableSpills &Spills,
-                             SmallSet<MachineInstr*, 4> &ReMatDefs,
-                             BitVector &RegKills,
-                             std::vector<MachineOperand*> &KillOps,
-                             VirtRegMap &VRM);
-    void RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
-                    AvailableSpills &Spills,
-                    BitVector &RegKills, std::vector<MachineOperand*> &KillOps);
-  };
-}
-
-/// InvalidateKills - MI is going to be deleted. If any of its operands are
-/// marked kill, then invalidate the information.
-static void InvalidateKills(MachineInstr &MI, BitVector &RegKills,
-                            std::vector<MachineOperand*> &KillOps,
-                            SmallVector<unsigned, 2> *KillRegs = NULL) {
-  for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
-    MachineOperand &MO = MI.getOperand(i);
-    if (!MO.isReg() || !MO.isUse() || !MO.isKill())
-      continue;
-    unsigned Reg = MO.getReg();
-    if (TargetRegisterInfo::isVirtualRegister(Reg))
-      continue;
-    if (KillRegs)
-      KillRegs->push_back(Reg);
-    assert(Reg < KillOps.size());
-    if (KillOps[Reg] == &MO) {
-      RegKills.reset(Reg);
-      KillOps[Reg] = NULL;
-    }
-  }
-}
-
-/// InvalidateRegDef - If the def operand of the specified def MI is now dead
-/// (since it's spill instruction is removed), mark it isDead. Also checks if
-/// the def MI has other definition operands that are not dead. Returns it by
-/// reference.
-static bool InvalidateRegDef(MachineBasicBlock::iterator I,
-                             MachineInstr &NewDef, unsigned Reg,
-                             bool &HasLiveDef) {
-  // Due to remat, it's possible this reg isn't being reused. That is,
-  // the def of this reg (by prev MI) is now dead.
-  MachineInstr *DefMI = I;
-  MachineOperand *DefOp = NULL;
-  for (unsigned i = 0, e = DefMI->getNumOperands(); i != e; ++i) {
-    MachineOperand &MO = DefMI->getOperand(i);
-    if (MO.isReg() && MO.isDef()) {
-      if (MO.getReg() == Reg)
-        DefOp = &MO;
-      else if (!MO.isDead())
-        HasLiveDef = true;
-    }
-  }
-  if (!DefOp)
-    return false;
-
-  bool FoundUse = false, Done = false;
-  MachineBasicBlock::iterator E = &NewDef;
-  ++I; ++E;
-  for (; !Done && I != E; ++I) {
-    MachineInstr *NMI = I;
-    for (unsigned j = 0, ee = NMI->getNumOperands(); j != ee; ++j) {
-      MachineOperand &MO = NMI->getOperand(j);
-      if (!MO.isReg() || MO.getReg() != Reg)
-        continue;
-      if (MO.isUse())
-        FoundUse = true;
-      Done = true; // Stop after scanning all the operands of this MI.
-    }
-  }
-  if (!FoundUse) {
-    // Def is dead!
-    DefOp->setIsDead();
-    return true;
-  }
-  return false;
-}
-
-/// UpdateKills - Track and update kill info. If a MI reads a register that is
-/// marked kill, then it must be due to register reuse. Transfer the kill info
-/// over.
-static void UpdateKills(MachineInstr &MI, BitVector &RegKills,
-                        std::vector<MachineOperand*> &KillOps,
-                        const TargetRegisterInfo* TRI) {
-  const TargetInstrDesc &TID = MI.getDesc();
-  for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
-    MachineOperand &MO = MI.getOperand(i);
-    if (!MO.isReg() || !MO.isUse())
-      continue;
-    unsigned Reg = MO.getReg();
-    if (Reg == 0)
-      continue;
-    
-    if (RegKills[Reg] && KillOps[Reg]->getParent() != &MI) {
-      // That can't be right. Register is killed but not re-defined and it's
-      // being reused. Let's fix that.
-      KillOps[Reg]->setIsKill(false);
-      KillOps[Reg] = NULL;
-      RegKills.reset(Reg);
-      if (i < TID.getNumOperands() &&
-          TID.getOperandConstraint(i, TOI::TIED_TO) == -1)
-        // Unless it's a two-address operand, this is the new kill.
-        MO.setIsKill();
-    }
-    if (MO.isKill()) {
-      RegKills.set(Reg);
-      KillOps[Reg] = &MO;
-    }
-  }
-
-  for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
-    const MachineOperand &MO = MI.getOperand(i);
-    if (!MO.isReg() || !MO.isDef())
-      continue;
-    unsigned Reg = MO.getReg();
-    RegKills.reset(Reg);
-    KillOps[Reg] = NULL;
-    // It also defines (or partially define) aliases.
-    for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS) {
-      RegKills.reset(*AS);
-      KillOps[*AS] = NULL;
-    }
-  }
-}
-
-/// ReMaterialize - Re-materialize definition for Reg targetting DestReg.
-///
-static void ReMaterialize(MachineBasicBlock &MBB,
-                          MachineBasicBlock::iterator &MII,
-                          unsigned DestReg, unsigned Reg,
-                          const TargetInstrInfo *TII,
-                          const TargetRegisterInfo *TRI,
-                          VirtRegMap &VRM) {
-  TII->reMaterialize(MBB, MII, DestReg, VRM.getReMaterializedMI(Reg));
-  MachineInstr *NewMI = prior(MII);
-  for (unsigned i = 0, e = NewMI->getNumOperands(); i != e; ++i) {
-    MachineOperand &MO = NewMI->getOperand(i);
-    if (!MO.isReg() || MO.getReg() == 0)
-      continue;
-    unsigned VirtReg = MO.getReg();
-    if (TargetRegisterInfo::isPhysicalRegister(VirtReg))
-      continue;
-    assert(MO.isUse());
-    unsigned SubIdx = MO.getSubReg();
-    unsigned Phys = VRM.getPhys(VirtReg);
-    assert(Phys);
-    unsigned RReg = SubIdx ? TRI->getSubReg(Phys, SubIdx) : Phys;
-    MO.setReg(RReg);
-  }
-  ++NumReMats;
-}
-
-
-// ReusedOp - For each reused operand, we keep track of a bit of information, in
-// case we need to rollback upon processing a new operand.  See comments below.
-namespace {
-  struct ReusedOp {
-    // The MachineInstr operand that reused an available value.
-    unsigned Operand;
-
-    // StackSlotOrReMat - The spill slot or remat id of the value being reused.
-    unsigned StackSlotOrReMat;
-
-    // PhysRegReused - The physical register the value was available in.
-    unsigned PhysRegReused;
-
-    // AssignedPhysReg - The physreg that was assigned for use by the reload.
-    unsigned AssignedPhysReg;
-    
-    // VirtReg - The virtual register itself.
-    unsigned VirtReg;
-
-    ReusedOp(unsigned o, unsigned ss, unsigned prr, unsigned apr,
-             unsigned vreg)
-      : Operand(o), StackSlotOrReMat(ss), PhysRegReused(prr),
-        AssignedPhysReg(apr), VirtReg(vreg) {}
-  };
-  
-  /// ReuseInfo - This maintains a collection of ReuseOp's for each operand that
-  /// is reused instead of reloaded.
-  class VISIBILITY_HIDDEN ReuseInfo {
-    MachineInstr &MI;
-    std::vector<ReusedOp> Reuses;
-    BitVector PhysRegsClobbered;
-  public:
-    ReuseInfo(MachineInstr &mi, const TargetRegisterInfo *tri) : MI(mi) {
-      PhysRegsClobbered.resize(tri->getNumRegs());
-    }
-    
-    bool hasReuses() const {
-      return !Reuses.empty();
-    }
-    
-    /// addReuse - If we choose to reuse a virtual register that is already
-    /// available instead of reloading it, remember that we did so.
-    void addReuse(unsigned OpNo, unsigned StackSlotOrReMat,
-                  unsigned PhysRegReused, unsigned AssignedPhysReg,
-                  unsigned VirtReg) {
-      // If the reload is to the assigned register anyway, no undo will be
-      // required.
-      if (PhysRegReused == AssignedPhysReg) return;
-      
-      // Otherwise, remember this.
-      Reuses.push_back(ReusedOp(OpNo, StackSlotOrReMat, PhysRegReused, 
-                                AssignedPhysReg, VirtReg));
-    }
-
-    void markClobbered(unsigned PhysReg) {
-      PhysRegsClobbered.set(PhysReg);
-    }
-
-    bool isClobbered(unsigned PhysReg) const {
-      return PhysRegsClobbered.test(PhysReg);
-    }
-    
-    /// GetRegForReload - We are about to emit a reload into PhysReg.  If there
-    /// is some other operand that is using the specified register, either pick
-    /// a new register to use, or evict the previous reload and use this reg. 
-    unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI,
-                             AvailableSpills &Spills,
-                             std::vector<MachineInstr*> &MaybeDeadStores,
-                             SmallSet<unsigned, 8> &Rejected,
-                             BitVector &RegKills,
-                             std::vector<MachineOperand*> &KillOps,
-                             VirtRegMap &VRM) {
-      const TargetInstrInfo* TII = MI->getParent()->getParent()->getTarget()
-                                   .getInstrInfo();
-      
-      if (Reuses.empty()) return PhysReg;  // This is most often empty.
-
-      for (unsigned ro = 0, e = Reuses.size(); ro != e; ++ro) {
-        ReusedOp &Op = Reuses[ro];
-        // If we find some other reuse that was supposed to use this register
-        // exactly for its reload, we can change this reload to use ITS reload
-        // register. That is, unless its reload register has already been
-        // considered and subsequently rejected because it has also been reused
-        // by another operand.
-        if (Op.PhysRegReused == PhysReg &&
-            Rejected.count(Op.AssignedPhysReg) == 0) {
-          // Yup, use the reload register that we didn't use before.
-          unsigned NewReg = Op.AssignedPhysReg;
-          Rejected.insert(PhysReg);
-          return GetRegForReload(NewReg, MI, Spills, MaybeDeadStores, Rejected,
-                                 RegKills, KillOps, VRM);
-        } else {
-          // Otherwise, we might also have a problem if a previously reused
-          // value aliases the new register.  If so, codegen the previous reload
-          // and use this one.          
-          unsigned PRRU = Op.PhysRegReused;
-          const TargetRegisterInfo *TRI = Spills.getRegInfo();
-          if (TRI->areAliases(PRRU, PhysReg)) {
-            // Okay, we found out that an alias of a reused register
-            // was used.  This isn't good because it means we have
-            // to undo a previous reuse.
-            MachineBasicBlock *MBB = MI->getParent();
-            const TargetRegisterClass *AliasRC =
-              MBB->getParent()->getRegInfo().getRegClass(Op.VirtReg);
-
-            // Copy Op out of the vector and remove it, we're going to insert an
-            // explicit load for it.
-            ReusedOp NewOp = Op;
-            Reuses.erase(Reuses.begin()+ro);
-
-            // Ok, we're going to try to reload the assigned physreg into the
-            // slot that we were supposed to in the first place.  However, that
-            // register could hold a reuse.  Check to see if it conflicts or
-            // would prefer us to use a different register.
-            unsigned NewPhysReg = GetRegForReload(NewOp.AssignedPhysReg,
-                                                  MI, Spills, MaybeDeadStores,
-                                              Rejected, RegKills, KillOps, VRM);
-            
-            MachineBasicBlock::iterator MII = MI;
-            if (NewOp.StackSlotOrReMat > VirtRegMap::MAX_STACK_SLOT) {
-              ReMaterialize(*MBB, MII, NewPhysReg, NewOp.VirtReg, TII, TRI,VRM);
-            } else {
-              TII->loadRegFromStackSlot(*MBB, MII, NewPhysReg,
-                                        NewOp.StackSlotOrReMat, AliasRC);
-              MachineInstr *LoadMI = prior(MII);
-              VRM.addSpillSlotUse(NewOp.StackSlotOrReMat, LoadMI);
-              // Any stores to this stack slot are not dead anymore.
-              MaybeDeadStores[NewOp.StackSlotOrReMat] = NULL;            
-              ++NumLoads;
-            }
-            Spills.ClobberPhysReg(NewPhysReg);
-            Spills.ClobberPhysReg(NewOp.PhysRegReused);
-
-            unsigned SubIdx = MI->getOperand(NewOp.Operand).getSubReg();
-            unsigned RReg = SubIdx ? TRI->getSubReg(NewPhysReg, SubIdx) : NewPhysReg;
-            MI->getOperand(NewOp.Operand).setReg(RReg);
-            
-            Spills.addAvailable(NewOp.StackSlotOrReMat, NewPhysReg);
-            --MII;
-            UpdateKills(*MII, RegKills, KillOps, TRI);
-            DOUT << '\t' << *MII;
-            
-            DOUT << "Reuse undone!\n";
-            --NumReused;
-            
-            // Finally, PhysReg is now available, go ahead and use it.
-            return PhysReg;
-          }
-        }
-      }
-      return PhysReg;
-    }
-
-    /// GetRegForReload - Helper for the above GetRegForReload(). Add a
-    /// 'Rejected' set to remember which registers have been considered and
-    /// rejected for the reload. This avoids infinite looping in case like
-    /// this:
-    /// t1 := op t2, t3
-    /// t2 <- assigned r0 for use by the reload but ended up reuse r1
-    /// t3 <- assigned r1 for use by the reload but ended up reuse r0
-    /// t1 <- desires r1
-    ///       sees r1 is taken by t2, tries t2's reload register r0
-    ///       sees r0 is taken by t3, tries t3's reload register r1
-    ///       sees r1 is taken by t2, tries t2's reload register r0 ...
-    unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI,
-                             AvailableSpills &Spills,
-                             std::vector<MachineInstr*> &MaybeDeadStores,
-                             BitVector &RegKills,
-                             std::vector<MachineOperand*> &KillOps,
-                             VirtRegMap &VRM) {
-      SmallSet<unsigned, 8> Rejected;
-      return GetRegForReload(PhysReg, MI, Spills, MaybeDeadStores, Rejected,
-                             RegKills, KillOps, VRM);
-    }
-  };
-}
-
-/// PrepForUnfoldOpti - Turn a store folding instruction into a load folding
-/// instruction. e.g.
-///     xorl  %edi, %eax
-///     movl  %eax, -32(%ebp)
-///     movl  -36(%ebp), %eax
-///     orl   %eax, -32(%ebp)
-/// ==>
-///     xorl  %edi, %eax
-///     orl   -36(%ebp), %eax
-///     mov   %eax, -32(%ebp)
-/// This enables unfolding optimization for a subsequent instruction which will
-/// also eliminate the newly introduced store instruction.
-bool LocalSpiller::PrepForUnfoldOpti(MachineBasicBlock &MBB,
-                                    MachineBasicBlock::iterator &MII,
-                                    std::vector<MachineInstr*> &MaybeDeadStores,
-                                    AvailableSpills &Spills,
-                                    BitVector &RegKills,
-                                    std::vector<MachineOperand*> &KillOps,
-                                    VirtRegMap &VRM) {
-  MachineFunction &MF = *MBB.getParent();
-  MachineInstr &MI = *MII;
-  unsigned UnfoldedOpc = 0;
-  unsigned UnfoldPR = 0;
-  unsigned UnfoldVR = 0;
-  int FoldedSS = VirtRegMap::NO_STACK_SLOT;
-  VirtRegMap::MI2VirtMapTy::const_iterator I, End;
-  for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ) {
-    // Only transform a MI that folds a single register.
-    if (UnfoldedOpc)
-      return false;
-    UnfoldVR = I->second.first;
-    VirtRegMap::ModRef MR = I->second.second;
-    // MI2VirtMap be can updated which invalidate the iterator.
-    // Increment the iterator first.
-    ++I; 
-    if (VRM.isAssignedReg(UnfoldVR))
-      continue;
-    // If this reference is not a use, any previous store is now dead.
-    // Otherwise, the store to this stack slot is not dead anymore.
-    FoldedSS = VRM.getStackSlot(UnfoldVR);
-    MachineInstr* DeadStore = MaybeDeadStores[FoldedSS];
-    if (DeadStore && (MR & VirtRegMap::isModRef)) {
-      unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(FoldedSS);
-      if (!PhysReg || !DeadStore->readsRegister(PhysReg))
-        continue;
-      UnfoldPR = PhysReg;
-      UnfoldedOpc = TII->getOpcodeAfterMemoryUnfold(MI.getOpcode(),
-                                                    false, true);
-    }
-  }
-
-  if (!UnfoldedOpc)
-    return false;
-
-  for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
-    MachineOperand &MO = MI.getOperand(i);
-    if (!MO.isReg() || MO.getReg() == 0 || !MO.isUse())
-      continue;
-    unsigned VirtReg = MO.getReg();
-    if (TargetRegisterInfo::isPhysicalRegister(VirtReg) || MO.getSubReg())
-      continue;
-    if (VRM.isAssignedReg(VirtReg)) {
-      unsigned PhysReg = VRM.getPhys(VirtReg);
-      if (PhysReg && TRI->regsOverlap(PhysReg, UnfoldPR))
-        return false;
-    } else if (VRM.isReMaterialized(VirtReg))
-      continue;
-    int SS = VRM.getStackSlot(VirtReg);
-    unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
-    if (PhysReg) {
-      if (TRI->regsOverlap(PhysReg, UnfoldPR))
-        return false;
-      continue;
-    }
-    if (VRM.hasPhys(VirtReg)) {
-      PhysReg = VRM.getPhys(VirtReg);
-      if (!TRI->regsOverlap(PhysReg, UnfoldPR))
-        continue;
-    }
-
-    // Ok, we'll need to reload the value into a register which makes
-    // it impossible to perform the store unfolding optimization later.
-    // Let's see if it is possible to fold the load if the store is
-    // unfolded. This allows us to perform the store unfolding
-    // optimization.
-    SmallVector<MachineInstr*, 4> NewMIs;
-    if (TII->unfoldMemoryOperand(MF, &MI, UnfoldVR, false, false, NewMIs)) {
-      assert(NewMIs.size() == 1);
-      MachineInstr *NewMI = NewMIs.back();
-      NewMIs.clear();
-      int Idx = NewMI->findRegisterUseOperandIdx(VirtReg, false);
-      assert(Idx != -1);
-      SmallVector<unsigned, 1> Ops;
-      Ops.push_back(Idx);
-      MachineInstr *FoldedMI = TII->foldMemoryOperand(MF, NewMI, Ops, SS);
-      if (FoldedMI) {
-        VRM.addSpillSlotUse(SS, FoldedMI);
-        if (!VRM.hasPhys(UnfoldVR))
-          VRM.assignVirt2Phys(UnfoldVR, UnfoldPR);
-        VRM.virtFolded(VirtReg, FoldedMI, VirtRegMap::isRef);
-        MII = MBB.insert(MII, FoldedMI);
-        InvalidateKills(MI, RegKills, KillOps);
-        VRM.RemoveMachineInstrFromMaps(&MI);
-        MBB.erase(&MI);
-        MF.DeleteMachineInstr(NewMI);
-        return true;
-      }
-      MF.DeleteMachineInstr(NewMI);
-    }
-  }
-  return false;
-}
-
-/// CommuteToFoldReload -
-/// Look for
-/// r1 = load fi#1
-/// r1 = op r1, r2<kill>
-/// store r1, fi#1
-///
-/// If op is commutable and r2 is killed, then we can xform these to
-/// r2 = op r2, fi#1
-/// store r2, fi#1
-bool LocalSpiller::CommuteToFoldReload(MachineBasicBlock &MBB,
-                                    MachineBasicBlock::iterator &MII,
-                                    unsigned VirtReg, unsigned SrcReg, int SS,
-                                    AvailableSpills &Spills,
-                                    BitVector &RegKills,
-                                    std::vector<MachineOperand*> &KillOps,
-                                    const TargetRegisterInfo *TRI,
-                                    VirtRegMap &VRM) {
-  if (MII == MBB.begin() || !MII->killsRegister(SrcReg))
-    return false;
-
-  MachineFunction &MF = *MBB.getParent();
-  MachineInstr &MI = *MII;
-  MachineBasicBlock::iterator DefMII = prior(MII);
-  MachineInstr *DefMI = DefMII;
-  const TargetInstrDesc &TID = DefMI->getDesc();
-  unsigned NewDstIdx;
-  if (DefMII != MBB.begin() &&
-      TID.isCommutable() &&
-      TII->CommuteChangesDestination(DefMI, NewDstIdx)) {
-    MachineOperand &NewDstMO = DefMI->getOperand(NewDstIdx);
-    unsigned NewReg = NewDstMO.getReg();
-    if (!NewDstMO.isKill() || TRI->regsOverlap(NewReg, SrcReg))
-      return false;
-    MachineInstr *ReloadMI = prior(DefMII);
-    int FrameIdx;
-    unsigned DestReg = TII->isLoadFromStackSlot(ReloadMI, FrameIdx);
-    if (DestReg != SrcReg || FrameIdx != SS)
-      return false;
-    int UseIdx = DefMI->findRegisterUseOperandIdx(DestReg, false);
-    if (UseIdx == -1)
-      return false;
-    int DefIdx = TID.getOperandConstraint(UseIdx, TOI::TIED_TO);
-    if (DefIdx == -1)
-      return false;
-    assert(DefMI->getOperand(DefIdx).isReg() &&
-           DefMI->getOperand(DefIdx).getReg() == SrcReg);
-
-    // Now commute def instruction.
-    MachineInstr *CommutedMI = TII->commuteInstruction(DefMI, true);
-    if (!CommutedMI)
-      return false;
-    SmallVector<unsigned, 1> Ops;
-    Ops.push_back(NewDstIdx);
-    MachineInstr *FoldedMI = TII->foldMemoryOperand(MF, CommutedMI, Ops, SS);
-    // Not needed since foldMemoryOperand returns new MI.
-    MF.DeleteMachineInstr(CommutedMI);
-    if (!FoldedMI)
-      return false;
-
-    VRM.addSpillSlotUse(SS, FoldedMI);
-    VRM.virtFolded(VirtReg, FoldedMI, VirtRegMap::isRef);
-    // Insert new def MI and spill MI.
-    const TargetRegisterClass* RC = MF.getRegInfo().getRegClass(VirtReg);
-    TII->storeRegToStackSlot(MBB, &MI, NewReg, true, SS, RC);
-    MII = prior(MII);
-    MachineInstr *StoreMI = MII;
-    VRM.addSpillSlotUse(SS, StoreMI);
-    VRM.virtFolded(VirtReg, StoreMI, VirtRegMap::isMod);
-    MII = MBB.insert(MII, FoldedMI);  // Update MII to backtrack.
-
-    // Delete all 3 old instructions.
-    InvalidateKills(*ReloadMI, RegKills, KillOps);
-    VRM.RemoveMachineInstrFromMaps(ReloadMI);
-    MBB.erase(ReloadMI);
-    InvalidateKills(*DefMI, RegKills, KillOps);
-    VRM.RemoveMachineInstrFromMaps(DefMI);
-    MBB.erase(DefMI);
-    InvalidateKills(MI, RegKills, KillOps);
-    VRM.RemoveMachineInstrFromMaps(&MI);
-    MBB.erase(&MI);
-
-    // If NewReg was previously holding value of some SS, it's now clobbered.
-    // This has to be done now because it's a physical register. When this
-    // instruction is re-visited, it's ignored.
-    Spills.ClobberPhysReg(NewReg);
-
-    ++NumCommutes;
-    return true;
-  }
-
-  return false;
-}
-
-/// findSuperReg - Find the SubReg's super-register of given register class
-/// where its SubIdx sub-register is SubReg.
-static unsigned findSuperReg(const TargetRegisterClass *RC, unsigned SubReg,
-                             unsigned SubIdx, const TargetRegisterInfo *TRI) {
-  for (TargetRegisterClass::iterator I = RC->begin(), E = RC->end();
-       I != E; ++I) {
-    unsigned Reg = *I;
-    if (TRI->getSubReg(Reg, SubIdx) == SubReg)
-      return Reg;
-  }
-  return 0;
-}
-
-/// SpillRegToStackSlot - Spill a register to a specified stack slot. Check if
-/// the last store to the same slot is now dead. If so, remove the last store.
-void LocalSpiller::SpillRegToStackSlot(MachineBasicBlock &MBB,
-                                  MachineBasicBlock::iterator &MII,
-                                  int Idx, unsigned PhysReg, int StackSlot,
-                                  const TargetRegisterClass *RC,
-                                  bool isAvailable, MachineInstr *&LastStore,
-                                  AvailableSpills &Spills,
-                                  SmallSet<MachineInstr*, 4> &ReMatDefs,
-                                  BitVector &RegKills,
-                                  std::vector<MachineOperand*> &KillOps,
-                                  VirtRegMap &VRM) {
-  TII->storeRegToStackSlot(MBB, next(MII), PhysReg, true, StackSlot, RC);
-  MachineInstr *StoreMI = next(MII);
-  VRM.addSpillSlotUse(StackSlot, StoreMI);
-  DOUT << "Store:\t" << *StoreMI;
-
-  // If there is a dead store to this stack slot, nuke it now.
-  if (LastStore) {
-    DOUT << "Removed dead store:\t" << *LastStore;
-    ++NumDSE;
-    SmallVector<unsigned, 2> KillRegs;
-    InvalidateKills(*LastStore, RegKills, KillOps, &KillRegs);
-    MachineBasicBlock::iterator PrevMII = LastStore;
-    bool CheckDef = PrevMII != MBB.begin();
-    if (CheckDef)
-      --PrevMII;
-    VRM.RemoveMachineInstrFromMaps(LastStore);
-    MBB.erase(LastStore);
-    if (CheckDef) {
-      // Look at defs of killed registers on the store. Mark the defs
-      // as dead since the store has been deleted and they aren't
-      // being reused.
-      for (unsigned j = 0, ee = KillRegs.size(); j != ee; ++j) {
-        bool HasOtherDef = false;
-        if (InvalidateRegDef(PrevMII, *MII, KillRegs[j], HasOtherDef)) {
-          MachineInstr *DeadDef = PrevMII;
-          if (ReMatDefs.count(DeadDef) && !HasOtherDef) {
-            // FIXME: This assumes a remat def does not have side
-            // effects.
-            VRM.RemoveMachineInstrFromMaps(DeadDef);
-            MBB.erase(DeadDef);
-            ++NumDRM;
-          }
-        }
-      }
-    }
-  }
-
-  LastStore = next(MII);
-
-  // If the stack slot value was previously available in some other
-  // register, change it now.  Otherwise, make the register available,
-  // in PhysReg.
-  Spills.ModifyStackSlotOrReMat(StackSlot);
-  Spills.ClobberPhysReg(PhysReg);
-  Spills.addAvailable(StackSlot, PhysReg, isAvailable);
-  ++NumStores;
-}
-
-/// TransferDeadness - A identity copy definition is dead and it's being
-/// removed. Find the last def or use and mark it as dead / kill.
-void LocalSpiller::TransferDeadness(MachineBasicBlock *MBB, unsigned CurDist,
-                                    unsigned Reg, BitVector &RegKills,
-                                    std::vector<MachineOperand*> &KillOps) {
-  int LastUDDist = -1;
-  MachineInstr *LastUDMI = NULL;
-  for (MachineRegisterInfo::reg_iterator RI = RegInfo->reg_begin(Reg),
-         RE = RegInfo->reg_end(); RI != RE; ++RI) {
-    MachineInstr *UDMI = &*RI;
-    if (UDMI->getParent() != MBB)
-      continue;
-    DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UDMI);
-    if (DI == DistanceMap.end() || DI->second > CurDist)
-      continue;
-    if ((int)DI->second < LastUDDist)
-      continue;
-    LastUDDist = DI->second;
-    LastUDMI = UDMI;
-  }
-
-  if (LastUDMI) {
-    const TargetInstrDesc &TID = LastUDMI->getDesc();
-    MachineOperand *LastUD = NULL;
-    for (unsigned i = 0, e = LastUDMI->getNumOperands(); i != e; ++i) {
-      MachineOperand &MO = LastUDMI->getOperand(i);
-      if (!MO.isReg() || MO.getReg() != Reg)
-        continue;
-      if (!LastUD || (LastUD->isUse() && MO.isDef()))
-        LastUD = &MO;
-      if (TID.getOperandConstraint(i, TOI::TIED_TO) != -1)
-        return;
-    }
-    if (LastUD->isDef())
-      LastUD->setIsDead();
-    else {
-      LastUD->setIsKill();
-      RegKills.set(Reg);
-      KillOps[Reg] = LastUD;
-    }
-  }
-}
-
-/// rewriteMBB - Keep track of which spills are available even after the
-/// register allocator is done with them.  If possible, avid reloading vregs.
-void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
-                              AvailableSpills &Spills, BitVector &RegKills,
-                              std::vector<MachineOperand*> &KillOps) {
-  DOUT << "\n**** Local spiller rewriting MBB '"
-       << MBB.getBasicBlock()->getName() << ":\n";
-
-  MachineFunction &MF = *MBB.getParent();
-  
-  // MaybeDeadStores - When we need to write a value back into a stack slot,
-  // keep track of the inserted store.  If the stack slot value is never read
-  // (because the value was used from some available register, for example), and
-  // subsequently stored to, the original store is dead.  This map keeps track
-  // of inserted stores that are not used.  If we see a subsequent store to the
-  // same stack slot, the original store is deleted.
-  std::vector<MachineInstr*> MaybeDeadStores;
-  MaybeDeadStores.resize(MF.getFrameInfo()->getObjectIndexEnd(), NULL);
-
-  // ReMatDefs - These are rematerializable def MIs which are not deleted.
-  SmallSet<MachineInstr*, 4> ReMatDefs;
-
-  // Clear kill info.
-  SmallSet<unsigned, 2> KilledMIRegs;
-  RegKills.reset();
-  KillOps.clear();
-  KillOps.resize(TRI->getNumRegs(), NULL);
-
-  unsigned Dist = 0;
-  DistanceMap.clear();
-  for (MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end();
-       MII != E; ) {
-    MachineBasicBlock::iterator NextMII = MII; ++NextMII;
-
-    VirtRegMap::MI2VirtMapTy::const_iterator I, End;
-    bool Erased = false;
-    bool BackTracked = false;
-    if (PrepForUnfoldOpti(MBB, MII,
-                          MaybeDeadStores, Spills, RegKills, KillOps, VRM))
-      NextMII = next(MII);
-
-    MachineInstr &MI = *MII;
-    const TargetInstrDesc &TID = MI.getDesc();
-
-    if (VRM.hasEmergencySpills(&MI)) {
-      // Spill physical register(s) in the rare case the allocator has run out
-      // of registers to allocate.
-      SmallSet<int, 4> UsedSS;
-      std::vector<unsigned> &EmSpills = VRM.getEmergencySpills(&MI);
-      for (unsigned i = 0, e = EmSpills.size(); i != e; ++i) {
-        unsigned PhysReg = EmSpills[i];
-        const TargetRegisterClass *RC =
-          TRI->getPhysicalRegisterRegClass(PhysReg);
-        assert(RC && "Unable to determine register class!");
-        int SS = VRM.getEmergencySpillSlot(RC);
-        if (UsedSS.count(SS))
-          assert(0 && "Need to spill more than one physical registers!");
-        UsedSS.insert(SS);
-        TII->storeRegToStackSlot(MBB, MII, PhysReg, true, SS, RC);
-        MachineInstr *StoreMI = prior(MII);
-        VRM.addSpillSlotUse(SS, StoreMI);
-        TII->loadRegFromStackSlot(MBB, next(MII), PhysReg, SS, RC);
-        MachineInstr *LoadMI = next(MII);
-        VRM.addSpillSlotUse(SS, LoadMI);
-        ++NumPSpills;
-      }
-      NextMII = next(MII);
-    }
-
-    // Insert restores here if asked to.
-    if (VRM.isRestorePt(&MI)) {
-      std::vector<unsigned> &RestoreRegs = VRM.getRestorePtRestores(&MI);
-      for (unsigned i = 0, e = RestoreRegs.size(); i != e; ++i) {
-        unsigned VirtReg = RestoreRegs[e-i-1];  // Reverse order.
-        if (!VRM.getPreSplitReg(VirtReg))
-          continue; // Split interval spilled again.
-        unsigned Phys = VRM.getPhys(VirtReg);
-        RegInfo->setPhysRegUsed(Phys);
-
-        // Check if the value being restored if available. If so, it must be
-        // from a predecessor BB that fallthrough into this BB. We do not
-        // expect:
-        // BB1:
-        // r1 = load fi#1
-        // ...
-        //    = r1<kill>
-        // ... # r1 not clobbered
-        // ...
-        //    = load fi#1
-        bool DoReMat = VRM.isReMaterialized(VirtReg);
-        int SSorRMId = DoReMat
-          ? VRM.getReMatId(VirtReg) : VRM.getStackSlot(VirtReg);
-        const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
-        unsigned InReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId);
-        if (InReg == Phys) {
-          // If the value is already available in the expected register, save
-          // a reload / remat.
-          if (SSorRMId)
-            DOUT << "Reusing RM#" << SSorRMId-VirtRegMap::MAX_STACK_SLOT-1;
-          else
-            DOUT << "Reusing SS#" << SSorRMId;
-          DOUT << " from physreg "
-               << TRI->getName(InReg) << " for vreg"
-               << VirtReg <<" instead of reloading into physreg "
-               << TRI->getName(Phys) << "\n";
-          ++NumOmitted;
-          continue;
-        } else if (InReg && InReg != Phys) {
-          if (SSorRMId)
-            DOUT << "Reusing RM#" << SSorRMId-VirtRegMap::MAX_STACK_SLOT-1;
-          else
-            DOUT << "Reusing SS#" << SSorRMId;
-          DOUT << " from physreg "
-               << TRI->getName(InReg) << " for vreg"
-               << VirtReg <<" by copying it into physreg "
-               << TRI->getName(Phys) << "\n";
-
-          // If the reloaded / remat value is available in another register,
-          // copy it to the desired register.
-          TII->copyRegToReg(MBB, &MI, Phys, InReg, RC, RC);
-
-          // This invalidates Phys.
-          Spills.ClobberPhysReg(Phys);
-          // Remember it's available.
-          Spills.addAvailable(SSorRMId, Phys);
-
-          // Mark is killed.
-          MachineInstr *CopyMI = prior(MII);
-          MachineOperand *KillOpnd = CopyMI->findRegisterUseOperand(InReg);
-          KillOpnd->setIsKill();
-          UpdateKills(*CopyMI, RegKills, KillOps, TRI);
-
-          DOUT << '\t' << *CopyMI;
-          ++NumCopified;
-          continue;
-        }
-
-        if (VRM.isReMaterialized(VirtReg)) {
-          ReMaterialize(MBB, MII, Phys, VirtReg, TII, TRI, VRM);
-        } else {
-          const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
-          TII->loadRegFromStackSlot(MBB, &MI, Phys, SSorRMId, RC);
-          MachineInstr *LoadMI = prior(MII);
-          VRM.addSpillSlotUse(SSorRMId, LoadMI);
-          ++NumLoads;
-        }
-
-        // This invalidates Phys.
-        Spills.ClobberPhysReg(Phys);
-        // Remember it's available.
-        Spills.addAvailable(SSorRMId, Phys);
-
-        UpdateKills(*prior(MII), RegKills, KillOps, TRI);
-        DOUT << '\t' << *prior(MII);
-      }
-    }
-
-    // Insert spills here if asked to.
-    if (VRM.isSpillPt(&MI)) {
-      std::vector<std::pair<unsigned,bool> > &SpillRegs =
-        VRM.getSpillPtSpills(&MI);
-      for (unsigned i = 0, e = SpillRegs.size(); i != e; ++i) {
-        unsigned VirtReg = SpillRegs[i].first;
-        bool isKill = SpillRegs[i].second;
-        if (!VRM.getPreSplitReg(VirtReg))
-          continue; // Split interval spilled again.
-        const TargetRegisterClass *RC = RegInfo->getRegClass(VirtReg);
-        unsigned Phys = VRM.getPhys(VirtReg);
-        int StackSlot = VRM.getStackSlot(VirtReg);
-        TII->storeRegToStackSlot(MBB, next(MII), Phys, isKill, StackSlot, RC);
-        MachineInstr *StoreMI = next(MII);
-        VRM.addSpillSlotUse(StackSlot, StoreMI);
-        DOUT << "Store:\t" << *StoreMI;
-        VRM.virtFolded(VirtReg, StoreMI, VirtRegMap::isMod);
-      }
-      NextMII = next(MII);
-    }
-
-    /// ReusedOperands - Keep track of operand reuse in case we need to undo
-    /// reuse.
-    ReuseInfo ReusedOperands(MI, TRI);
-    SmallVector<unsigned, 4> VirtUseOps;
-    for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
-      MachineOperand &MO = MI.getOperand(i);
-      if (!MO.isReg() || MO.getReg() == 0)
-        continue;   // Ignore non-register operands.
-      
-      unsigned VirtReg = MO.getReg();
-      if (TargetRegisterInfo::isPhysicalRegister(VirtReg)) {
-        // Ignore physregs for spilling, but remember that it is used by this
-        // function.
-        RegInfo->setPhysRegUsed(VirtReg);
-        continue;
-      }
-
-      // We want to process implicit virtual register uses first.
-      if (MO.isImplicit())
-        // If the virtual register is implicitly defined, emit a implicit_def
-        // before so scavenger knows it's "defined".
-        VirtUseOps.insert(VirtUseOps.begin(), i);
-      else
-        VirtUseOps.push_back(i);
-    }
-
-    // Process all of the spilled uses and all non spilled reg references.
-    SmallVector<int, 2> PotentialDeadStoreSlots;
-    KilledMIRegs.clear();
-    for (unsigned j = 0, e = VirtUseOps.size(); j != e; ++j) {
-      unsigned i = VirtUseOps[j];
-      MachineOperand &MO = MI.getOperand(i);
-      unsigned VirtReg = MO.getReg();
-      assert(TargetRegisterInfo::isVirtualRegister(VirtReg) &&
-             "Not a virtual register?");
-
-      unsigned SubIdx = MO.getSubReg();
-      if (VRM.isAssignedReg(VirtReg)) {
-        // This virtual register was assigned a physreg!
-        unsigned Phys = VRM.getPhys(VirtReg);
-        RegInfo->setPhysRegUsed(Phys);
-        if (MO.isDef())
-          ReusedOperands.markClobbered(Phys);
-        unsigned RReg = SubIdx ? TRI->getSubReg(Phys, SubIdx) : Phys;
-        MI.getOperand(i).setReg(RReg);
-        if (VRM.isImplicitlyDefined(VirtReg))
-          BuildMI(MBB, &MI, MI.getDebugLoc(),
-                  TII->get(TargetInstrInfo::IMPLICIT_DEF), RReg);
-        continue;
-      }
-      
-      // This virtual register is now known to be a spilled value.
-      if (!MO.isUse())
-        continue;  // Handle defs in the loop below (handle use&def here though)
-
-      bool DoReMat = VRM.isReMaterialized(VirtReg);
-      int SSorRMId = DoReMat
-        ? VRM.getReMatId(VirtReg) : VRM.getStackSlot(VirtReg);
-      int ReuseSlot = SSorRMId;
-
-      // Check to see if this stack slot is available.
-      unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SSorRMId);
-
-      // If this is a sub-register use, make sure the reuse register is in the
-      // right register class. For example, for x86 not all of the 32-bit
-      // registers have accessible sub-registers.
-      // Similarly so for EXTRACT_SUBREG. Consider this:
-      // EDI = op
-      // MOV32_mr fi#1, EDI
-      // ...
-      //       = EXTRACT_SUBREG fi#1
-      // fi#1 is available in EDI, but it cannot be reused because it's not in
-      // the right register file.
-      if (PhysReg &&
-          (SubIdx || MI.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG)) {
-        const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
-        if (!RC->contains(PhysReg))
-          PhysReg = 0;
-      }
-
-      if (PhysReg) {
-        // This spilled operand might be part of a two-address operand.  If this
-        // is the case, then changing it will necessarily require changing the 
-        // def part of the instruction as well.  However, in some cases, we
-        // aren't allowed to modify the reused register.  If none of these cases
-        // apply, reuse it.
-        bool CanReuse = true;
-        int ti = TID.getOperandConstraint(i, TOI::TIED_TO);
-        if (ti != -1) {
-          // Okay, we have a two address operand.  We can reuse this physreg as
-          // long as we are allowed to clobber the value and there isn't an
-          // earlier def that has already clobbered the physreg.
-          CanReuse = Spills.canClobberPhysReg(ReuseSlot) &&
-            !ReusedOperands.isClobbered(PhysReg);
-        }
-        
-        if (CanReuse) {
-          // If this stack slot value is already available, reuse it!
-          if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT)
-            DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1;
-          else
-            DOUT << "Reusing SS#" << ReuseSlot;
-          DOUT << " from physreg "
-               << TRI->getName(PhysReg) << " for vreg"
-               << VirtReg <<" instead of reloading into physreg "
-               << TRI->getName(VRM.getPhys(VirtReg)) << "\n";
-          unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
-          MI.getOperand(i).setReg(RReg);
-
-          // The only technical detail we have is that we don't know that
-          // PhysReg won't be clobbered by a reloaded stack slot that occurs
-          // later in the instruction.  In particular, consider 'op V1, V2'.
-          // If V1 is available in physreg R0, we would choose to reuse it
-          // here, instead of reloading it into the register the allocator
-          // indicated (say R1).  However, V2 might have to be reloaded
-          // later, and it might indicate that it needs to live in R0.  When
-          // this occurs, we need to have information available that
-          // indicates it is safe to use R1 for the reload instead of R0.
-          //
-          // To further complicate matters, we might conflict with an alias,
-          // or R0 and R1 might not be compatible with each other.  In this
-          // case, we actually insert a reload for V1 in R1, ensuring that
-          // we can get at R0 or its alias.
-          ReusedOperands.addReuse(i, ReuseSlot, PhysReg,
-                                  VRM.getPhys(VirtReg), VirtReg);
-          if (ti != -1)
-            // Only mark it clobbered if this is a use&def operand.
-            ReusedOperands.markClobbered(PhysReg);
-          ++NumReused;
-
-          if (MI.getOperand(i).isKill() &&
-              ReuseSlot <= VirtRegMap::MAX_STACK_SLOT) {
-
-            // The store of this spilled value is potentially dead, but we
-            // won't know for certain until we've confirmed that the re-use
-            // above is valid, which means waiting until the other operands
-            // are processed. For now we just track the spill slot, we'll
-            // remove it after the other operands are processed if valid.
-
-            PotentialDeadStoreSlots.push_back(ReuseSlot);
-          }
-
-          // Mark is isKill if it's there no other uses of the same virtual
-          // register and it's not a two-address operand. IsKill will be
-          // unset if reg is reused.
-          if (ti == -1 && KilledMIRegs.count(VirtReg) == 0) {
-            MI.getOperand(i).setIsKill();
-            KilledMIRegs.insert(VirtReg);
-          }
-
-          continue;
-        }  // CanReuse
-        
-        // Otherwise we have a situation where we have a two-address instruction
-        // whose mod/ref operand needs to be reloaded.  This reload is already
-        // available in some register "PhysReg", but if we used PhysReg as the
-        // operand to our 2-addr instruction, the instruction would modify
-        // PhysReg.  This isn't cool if something later uses PhysReg and expects
-        // to get its initial value.
-        //
-        // To avoid this problem, and to avoid doing a load right after a store,
-        // we emit a copy from PhysReg into the designated register for this
-        // operand.
-        unsigned DesignatedReg = VRM.getPhys(VirtReg);
-        assert(DesignatedReg && "Must map virtreg to physreg!");
-
-        // Note that, if we reused a register for a previous operand, the
-        // register we want to reload into might not actually be
-        // available.  If this occurs, use the register indicated by the
-        // reuser.
-        if (ReusedOperands.hasReuses())
-          DesignatedReg = ReusedOperands.GetRegForReload(DesignatedReg, &MI, 
-                               Spills, MaybeDeadStores, RegKills, KillOps, VRM);
-        
-        // If the mapped designated register is actually the physreg we have
-        // incoming, we don't need to inserted a dead copy.
-        if (DesignatedReg == PhysReg) {
-          // If this stack slot value is already available, reuse it!
-          if (ReuseSlot > VirtRegMap::MAX_STACK_SLOT)
-            DOUT << "Reusing RM#" << ReuseSlot-VirtRegMap::MAX_STACK_SLOT-1;
-          else
-            DOUT << "Reusing SS#" << ReuseSlot;
-          DOUT << " from physreg " << TRI->getName(PhysReg)
-               << " for vreg" << VirtReg
-               << " instead of reloading into same physreg.\n";
-          unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
-          MI.getOperand(i).setReg(RReg);
-          ReusedOperands.markClobbered(RReg);
-          ++NumReused;
-          continue;
-        }
-        
-        const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
-        RegInfo->setPhysRegUsed(DesignatedReg);
-        ReusedOperands.markClobbered(DesignatedReg);
-        TII->copyRegToReg(MBB, &MI, DesignatedReg, PhysReg, RC, RC);
-
-        MachineInstr *CopyMI = prior(MII);
-        UpdateKills(*CopyMI, RegKills, KillOps, TRI);
-
-        // This invalidates DesignatedReg.
-        Spills.ClobberPhysReg(DesignatedReg);
-        
-        Spills.addAvailable(ReuseSlot, DesignatedReg);
-        unsigned RReg =
-          SubIdx ? TRI->getSubReg(DesignatedReg, SubIdx) : DesignatedReg;
-        MI.getOperand(i).setReg(RReg);
-        DOUT << '\t' << *prior(MII);
-        ++NumReused;
-        continue;
-      } // if (PhysReg)
-      
-      // Otherwise, reload it and remember that we have it.
-      PhysReg = VRM.getPhys(VirtReg);
-      assert(PhysReg && "Must map virtreg to physreg!");
-
-      // Note that, if we reused a register for a previous operand, the
-      // register we want to reload into might not actually be
-      // available.  If this occurs, use the register indicated by the
-      // reuser.
-      if (ReusedOperands.hasReuses())
-        PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI, 
-                               Spills, MaybeDeadStores, RegKills, KillOps, VRM);
-      
-      RegInfo->setPhysRegUsed(PhysReg);
-      ReusedOperands.markClobbered(PhysReg);
-      if (DoReMat) {
-        ReMaterialize(MBB, MII, PhysReg, VirtReg, TII, TRI, VRM);
-      } else {
-        const TargetRegisterClass* RC = RegInfo->getRegClass(VirtReg);
-        TII->loadRegFromStackSlot(MBB, &MI, PhysReg, SSorRMId, RC);
-        MachineInstr *LoadMI = prior(MII);
-        VRM.addSpillSlotUse(SSorRMId, LoadMI);
-        ++NumLoads;
-      }
-      // This invalidates PhysReg.
-      Spills.ClobberPhysReg(PhysReg);
-
-      // Any stores to this stack slot are not dead anymore.
-      if (!DoReMat)
-        MaybeDeadStores[SSorRMId] = NULL;
-      Spills.addAvailable(SSorRMId, PhysReg);
-      // Assumes this is the last use. IsKill will be unset if reg is reused
-      // unless it's a two-address operand.
-      if (TID.getOperandConstraint(i, TOI::TIED_TO) == -1 &&
-          KilledMIRegs.count(VirtReg) == 0) {
-        MI.getOperand(i).setIsKill();
-        KilledMIRegs.insert(VirtReg);
-      }
-      unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
-      MI.getOperand(i).setReg(RReg);
-      UpdateKills(*prior(MII), RegKills, KillOps, TRI);
-      DOUT << '\t' << *prior(MII);
-    }
-
-    // Ok - now we can remove stores that have been confirmed dead.
-    for (unsigned j = 0, e = PotentialDeadStoreSlots.size(); j != e; ++j) {
-      // This was the last use and the spilled value is still available
-      // for reuse. That means the spill was unnecessary!
-      int PDSSlot = PotentialDeadStoreSlots[j];
-      MachineInstr* DeadStore = MaybeDeadStores[PDSSlot];
-      if (DeadStore) {
-        DOUT << "Removed dead store:\t" << *DeadStore;
-        InvalidateKills(*DeadStore, RegKills, KillOps);
-        VRM.RemoveMachineInstrFromMaps(DeadStore);
-        MBB.erase(DeadStore);
-        MaybeDeadStores[PDSSlot] = NULL;
-        ++NumDSE;
-      }
-    }
-
-
-    DOUT << '\t' << MI;
-
-
-    // If we have folded references to memory operands, make sure we clear all
-    // physical registers that may contain the value of the spilled virtual
-    // register
-    SmallSet<int, 2> FoldedSS;
-    for (tie(I, End) = VRM.getFoldedVirts(&MI); I != End; ) {
-      unsigned VirtReg = I->second.first;
-      VirtRegMap::ModRef MR = I->second.second;
-      DOUT << "Folded vreg: " << VirtReg << "  MR: " << MR;
-
-      // MI2VirtMap be can updated which invalidate the iterator.
-      // Increment the iterator first.
-      ++I;
-      int SS = VRM.getStackSlot(VirtReg);
-      if (SS == VirtRegMap::NO_STACK_SLOT)
-        continue;
-      FoldedSS.insert(SS);
-      DOUT << " - StackSlot: " << SS << "\n";
-      
-      // If this folded instruction is just a use, check to see if it's a
-      // straight load from the virt reg slot.
-      if ((MR & VirtRegMap::isRef) && !(MR & VirtRegMap::isMod)) {
-        int FrameIdx;
-        unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx);
-        if (DestReg && FrameIdx == SS) {
-          // If this spill slot is available, turn it into a copy (or nothing)
-          // instead of leaving it as a load!
-          if (unsigned InReg = Spills.getSpillSlotOrReMatPhysReg(SS)) {
-            DOUT << "Promoted Load To Copy: " << MI;
-            if (DestReg != InReg) {
-              const TargetRegisterClass *RC = RegInfo->getRegClass(VirtReg);
-              TII->copyRegToReg(MBB, &MI, DestReg, InReg, RC, RC);
-              MachineOperand *DefMO = MI.findRegisterDefOperand(DestReg);
-              unsigned SubIdx = DefMO->getSubReg();
-              // Revisit the copy so we make sure to notice the effects of the
-              // operation on the destreg (either needing to RA it if it's 
-              // virtual or needing to clobber any values if it's physical).
-              NextMII = &MI;
-              --NextMII;  // backtrack to the copy.
-              // Propagate the sub-register index over.
-              if (SubIdx) {
-                DefMO = NextMII->findRegisterDefOperand(DestReg);
-                DefMO->setSubReg(SubIdx);
-              }
-
-              // Mark is killed.
-              MachineOperand *KillOpnd = NextMII->findRegisterUseOperand(InReg);
-              KillOpnd->setIsKill();
-
-              BackTracked = true;
-            } else {
-              DOUT << "Removing now-noop copy: " << MI;
-              // Unset last kill since it's being reused.
-              InvalidateKill(InReg, RegKills, KillOps);
-            }
-
-            InvalidateKills(MI, RegKills, KillOps);
-            VRM.RemoveMachineInstrFromMaps(&MI);
-            MBB.erase(&MI);
-            Erased = true;
-            goto ProcessNextInst;
-          }
-        } else {
-          unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
-          SmallVector<MachineInstr*, 4> NewMIs;
-          if (PhysReg &&
-              TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, false, NewMIs)) {
-            MBB.insert(MII, NewMIs[0]);
-            InvalidateKills(MI, RegKills, KillOps);
-            VRM.RemoveMachineInstrFromMaps(&MI);
-            MBB.erase(&MI);
-            Erased = true;
-            --NextMII;  // backtrack to the unfolded instruction.
-            BackTracked = true;
-            goto ProcessNextInst;
-          }
-        }
-      }
-
-      // If this reference is not a use, any previous store is now dead.
-      // Otherwise, the store to this stack slot is not dead anymore.
-      MachineInstr* DeadStore = MaybeDeadStores[SS];
-      if (DeadStore) {
-        bool isDead = !(MR & VirtRegMap::isRef);
-        MachineInstr *NewStore = NULL;
-        if (MR & VirtRegMap::isModRef) {
-          unsigned PhysReg = Spills.getSpillSlotOrReMatPhysReg(SS);
-          SmallVector<MachineInstr*, 4> NewMIs;
-          // We can reuse this physreg as long as we are allowed to clobber
-          // the value and there isn't an earlier def that has already clobbered
-          // the physreg.
-          if (PhysReg &&
-              !TII->isStoreToStackSlot(&MI, SS)) { // Not profitable!
-            MachineOperand *KillOpnd =
-              DeadStore->findRegisterUseOperand(PhysReg, true);
-            // Note, if the store is storing a sub-register, it's possible the
-            // super-register is needed below.
-            if (KillOpnd && !KillOpnd->getSubReg() &&
-                TII->unfoldMemoryOperand(MF, &MI, PhysReg, false, true,NewMIs)){
-             MBB.insert(MII, NewMIs[0]);
-              NewStore = NewMIs[1];
-              MBB.insert(MII, NewStore);
-              VRM.addSpillSlotUse(SS, NewStore);
-              InvalidateKills(MI, RegKills, KillOps);
-              VRM.RemoveMachineInstrFromMaps(&MI);
-              MBB.erase(&MI);
-              Erased = true;
-              --NextMII;
-              --NextMII;  // backtrack to the unfolded instruction.
-              BackTracked = true;
-              isDead = true;
-            }
-          }
-        }
-
-        if (isDead) {  // Previous store is dead.
-          // If we get here, the store is dead, nuke it now.
-          DOUT << "Removed dead store:\t" << *DeadStore;
-          InvalidateKills(*DeadStore, RegKills, KillOps);
-          VRM.RemoveMachineInstrFromMaps(DeadStore);
-          MBB.erase(DeadStore);
-          if (!NewStore)
-            ++NumDSE;
-        }
-
-        MaybeDeadStores[SS] = NULL;
-        if (NewStore) {
-          // Treat this store as a spill merged into a copy. That makes the
-          // stack slot value available.
-          VRM.virtFolded(VirtReg, NewStore, VirtRegMap::isMod);
-          goto ProcessNextInst;
-        }
-      }
-
-      // If the spill slot value is available, and this is a new definition of
-      // the value, the value is not available anymore.
-      if (MR & VirtRegMap::isMod) {
-        // Notice that the value in this stack slot has been modified.
-        Spills.ModifyStackSlotOrReMat(SS);
-        
-        // If this is *just* a mod of the value, check to see if this is just a
-        // store to the spill slot (i.e. the spill got merged into the copy). If
-        // so, realize that the vreg is available now, and add the store to the
-        // MaybeDeadStore info.
-        int StackSlot;
-        if (!(MR & VirtRegMap::isRef)) {
-          if (unsigned SrcReg = TII->isStoreToStackSlot(&MI, StackSlot)) {
-            assert(TargetRegisterInfo::isPhysicalRegister(SrcReg) &&
-                   "Src hasn't been allocated yet?");
-
-            if (CommuteToFoldReload(MBB, MII, VirtReg, SrcReg, StackSlot,
-                                    Spills, RegKills, KillOps, TRI, VRM)) {
-              NextMII = next(MII);
-              BackTracked = true;
-              goto ProcessNextInst;
-            }
-
-            // Okay, this is certainly a store of SrcReg to [StackSlot].  Mark
-            // this as a potentially dead store in case there is a subsequent
-            // store into the stack slot without a read from it.
-            MaybeDeadStores[StackSlot] = &MI;
-
-            // If the stack slot value was previously available in some other
-            // register, change it now.  Otherwise, make the register
-            // available in PhysReg.
-            Spills.addAvailable(StackSlot, SrcReg, false/*!clobber*/);
-          }
-        }
-      }
-    }
-
-    // Process all of the spilled defs.
-    for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
-      MachineOperand &MO = MI.getOperand(i);
-      if (!(MO.isReg() && MO.getReg() && MO.isDef()))
-        continue;
-
-      unsigned VirtReg = MO.getReg();
-      if (!TargetRegisterInfo::isVirtualRegister(VirtReg)) {
-        // Check to see if this is a noop copy.  If so, eliminate the
-        // instruction before considering the dest reg to be changed.
-        unsigned Src, Dst, SrcSR, DstSR;
-        if (TII->isMoveInstr(MI, Src, Dst, SrcSR, DstSR) && Src == Dst) {
-          ++NumDCE;
-          DOUT << "Removing now-noop copy: " << MI;
-          SmallVector<unsigned, 2> KillRegs;
-          InvalidateKills(MI, RegKills, KillOps, &KillRegs);
-          if (MO.isDead() && !KillRegs.empty()) {
-            // Source register or an implicit super/sub-register use is killed.
-            assert(KillRegs[0] == Dst ||
-                   TRI->isSubRegister(KillRegs[0], Dst) ||
-                   TRI->isSuperRegister(KillRegs[0], Dst));
-            // Last def is now dead.
-            TransferDeadness(&MBB, Dist, Src, RegKills, KillOps);
-          }
-          VRM.RemoveMachineInstrFromMaps(&MI);
-          MBB.erase(&MI);
-          Erased = true;
-          Spills.disallowClobberPhysReg(VirtReg);
-          goto ProcessNextInst;
-        }
-          
-        // If it's not a no-op copy, it clobbers the value in the destreg.
-        Spills.ClobberPhysReg(VirtReg);
-        ReusedOperands.markClobbered(VirtReg);
- 
-        // Check to see if this instruction is a load from a stack slot into
-        // a register.  If so, this provides the stack slot value in the reg.
-        int FrameIdx;
-        if (unsigned DestReg = TII->isLoadFromStackSlot(&MI, FrameIdx)) {
-          assert(DestReg == VirtReg && "Unknown load situation!");
-
-          // If it is a folded reference, then it's not safe to clobber.
-          bool Folded = FoldedSS.count(FrameIdx);
-          // Otherwise, if it wasn't available, remember that it is now!
-          Spills.addAvailable(FrameIdx, DestReg, !Folded);
-          goto ProcessNextInst;
-        }
-            
-        continue;
-      }
-
-      unsigned SubIdx = MO.getSubReg();
-      bool DoReMat = VRM.isReMaterialized(VirtReg);
-      if (DoReMat)
-        ReMatDefs.insert(&MI);
-
-      // The only vregs left are stack slot definitions.
-      int StackSlot = VRM.getStackSlot(VirtReg);
-      const TargetRegisterClass *RC = RegInfo->getRegClass(VirtReg);
-
-      // If this def is part of a two-address operand, make sure to execute
-      // the store from the correct physical register.
-      unsigned PhysReg;
-      int TiedOp = MI.getDesc().findTiedToSrcOperand(i);
-      if (TiedOp != -1) {
-        PhysReg = MI.getOperand(TiedOp).getReg();
-        if (SubIdx) {
-          unsigned SuperReg = findSuperReg(RC, PhysReg, SubIdx, TRI);
-          assert(SuperReg && TRI->getSubReg(SuperReg, SubIdx) == PhysReg &&
-                 "Can't find corresponding super-register!");
-          PhysReg = SuperReg;
-        }
-      } else {
-        PhysReg = VRM.getPhys(VirtReg);
-        if (ReusedOperands.isClobbered(PhysReg)) {
-          // Another def has taken the assigned physreg. It must have been a
-          // use&def which got it due to reuse. Undo the reuse!
-          PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI, 
-                               Spills, MaybeDeadStores, RegKills, KillOps, VRM);
-        }
-      }
-
-      assert(PhysReg && "VR not assigned a physical register?");
-      RegInfo->setPhysRegUsed(PhysReg);
-      unsigned RReg = SubIdx ? TRI->getSubReg(PhysReg, SubIdx) : PhysReg;
-      ReusedOperands.markClobbered(RReg);
-      MI.getOperand(i).setReg(RReg);
-
-      if (!MO.isDead()) {
-        MachineInstr *&LastStore = MaybeDeadStores[StackSlot];
-        SpillRegToStackSlot(MBB, MII, -1, PhysReg, StackSlot, RC, true,
-                          LastStore, Spills, ReMatDefs, RegKills, KillOps, VRM);
-        NextMII = next(MII);
-
-        // Check to see if this is a noop copy.  If so, eliminate the
-        // instruction before considering the dest reg to be changed.
-        {
-          unsigned Src, Dst, SrcSR, DstSR;
-          if (TII->isMoveInstr(MI, Src, Dst, SrcSR, DstSR) && Src == Dst) {
-            ++NumDCE;
-            DOUT << "Removing now-noop copy: " << MI;
-            InvalidateKills(MI, RegKills, KillOps);
-            VRM.RemoveMachineInstrFromMaps(&MI);
-            MBB.erase(&MI);
-            Erased = true;
-            UpdateKills(*LastStore, RegKills, KillOps, TRI);
-            goto ProcessNextInst;
-          }
-        }
-      }    
-    }
-  ProcessNextInst:
-    DistanceMap.insert(std::make_pair(&MI, Dist++));
-    if (!Erased && !BackTracked) {
-      for (MachineBasicBlock::iterator II = &MI; II != NextMII; ++II)
-        UpdateKills(*II, RegKills, KillOps, TRI);
-    }
-    MII = NextMII;
-  }
-
-}
-
-llvm::Spiller* llvm::createSpiller() {
-  switch (SpillerOpt) {
-  default: assert(0 && "Unreachable!");
-  case local:
-    return new LocalSpiller();
-  case simple:
-    return new SimpleSpiller();
-  }
-}
+}
\ No newline at end of file