ARM refactoring. Step 2: split RegisterInfo

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74384 91177308-0d34-0410-b5e6-96231b3b80d8

9 files changed, 1075 insertions, 694 deletions

diff --git a/lib/Target/ARM/ARMInstrInfo.cpp b/lib/Target/ARM/ARMInstrInfo.cpp
index d95089dd48..034b697ab5 100644
--- a/lib/Target/ARM/ARMInstrInfo.cpp
+++ b/lib/Target/ARM/ARMInstrInfo.cpp
@@ -40,12 +40,11 @@ const MachineInstrBuilder &AddDefaultCC(const MachineInstrBuilder &MIB) {
 }
 
 ARMBaseInstrInfo::ARMBaseInstrInfo(const ARMSubtarget &STI)
-  : TargetInstrInfoImpl(ARMInsts, array_lengthof(ARMInsts)),
-    RI(*this, STI) {
+  : TargetInstrInfoImpl(ARMInsts, array_lengthof(ARMInsts)) {
 }
 
 ARMInstrInfo::ARMInstrInfo(const ARMSubtarget &STI)
-  : ARMBaseInstrInfo(STI) {
+  : ARMBaseInstrInfo(STI), RI(*this, STI) {
 }
 
 /// Return true if the instruction is a register to register move and
@@ -133,15 +132,15 @@ unsigned ARMInstrInfo::isStoreToStackSlot(const MachineInstr *MI,
   return 0;
 }
 
-void ARMBaseInstrInfo::reMaterialize(MachineBasicBlock &MBB,
-                                     MachineBasicBlock::iterator I,
-                                     unsigned DestReg,
-                                     const MachineInstr *Orig) const {
+void ARMInstrInfo::reMaterialize(MachineBasicBlock &MBB,
+                                 MachineBasicBlock::iterator I,
+                                 unsigned DestReg,
+                                 const MachineInstr *Orig) const {
   DebugLoc dl = Orig->getDebugLoc();
   if (Orig->getOpcode() == ARM::MOVi2pieces) {
     RI.emitLoadConstPool(MBB, I, DestReg, Orig->getOperand(1).getImm(),
                          Orig->getOperand(2).getImm(),
-                         Orig->getOperand(3).getReg(), this, false, dl);
+                         Orig->getOperand(3).getReg(), this, dl);
     return;
   }
 
@@ -660,35 +659,17 @@ foldMemoryOperandImpl(MachineFunction &MF, MachineInstr *MI,
   return NewMI;
 }
 
-bool ARMBaseInstrInfo::
-canFoldMemoryOperand(const MachineInstr *MI,
-                     const SmallVectorImpl<unsigned> &Ops) const {
+bool
+ARMInstrInfo::canFoldMemoryOperand(const MachineInstr *MI,
+                                   const SmallVectorImpl<unsigned> &Ops) const {
   if (Ops.size() != 1) return false;
 
-  unsigned OpNum = Ops[0];
   unsigned Opc = MI->getOpcode();
   switch (Opc) {
   default: break;
   case ARM::MOVr:
     // If it is updating CPSR, then it cannot be folded.
     return MI->getOperand(4).getReg() != ARM::CPSR;
-  case ARM::tMOVr:
-  case ARM::tMOVlor2hir:
-  case ARM::tMOVhir2lor:
-  case ARM::tMOVhir2hir: {
-    if (OpNum == 0) { // move -> store
-      unsigned SrcReg = MI->getOperand(1).getReg();
-      if (RI.isPhysicalRegister(SrcReg) && !RI.isLowRegister(SrcReg))
-        // tSpill cannot take a high register operand.
-        return false;
-    } else {          // move -> load
-      unsigned DstReg = MI->getOperand(0).getReg();
-      if (RI.isPhysicalRegister(DstReg) && !RI.isLowRegister(DstReg))
-        // tRestore cannot target a high register operand.
-        return false;
-    }
-    return true;
-  }
   case ARM::FCPYS:
   case ARM::FCPYD:
     return true;
@@ -702,7 +683,7 @@ canFoldMemoryOperand(const MachineInstr *MI,
 }
 
 bool
-  ARMBaseInstrInfo::BlockHasNoFallThrough(const MachineBasicBlock &MBB) const {
+ARMBaseInstrInfo::BlockHasNoFallThrough(const MachineBasicBlock &MBB) const {
   if (MBB.empty()) return false;
 
   switch (MBB.back().getOpcode()) {
diff --git a/lib/Target/ARM/ARMInstrInfo.h b/lib/Target/ARM/ARMInstrInfo.h
index 131960b9c7..7e3aa6c7a3 100644
--- a/lib/Target/ARM/ARMInstrInfo.h
+++ b/lib/Target/ARM/ARMInstrInfo.h
@@ -147,21 +147,10 @@ namespace ARMII {
 }
 
 class ARMBaseInstrInfo : public TargetInstrInfoImpl {
-  const ARMRegisterInfo RI;
 protected:
   // Can be only subclassed.
   explicit ARMBaseInstrInfo(const ARMSubtarget &STI);
 public:
-
-  /// getRegisterInfo - TargetInstrInfo is a superset of MRegister info.  As
-  /// such, whenever a client has an instance of instruction info, it should
-  /// always be able to get register info as well (through this method).
-  ///
-  virtual const ARMRegisterInfo &getRegisterInfo() const { return RI; }
-
-  void reMaterialize(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
-                     unsigned DestReg, const MachineInstr *Orig) const;
-
   virtual MachineInstr *convertToThreeAddress(MachineFunction::iterator &MFI,
                                               MachineBasicBlock::iterator &MBBI,
                                               LiveVariables *LV) const;
@@ -176,9 +165,6 @@ public:
                                 MachineBasicBlock *FBB,
                             const SmallVectorImpl<MachineOperand> &Cond) const;
 
-  virtual bool canFoldMemoryOperand(const MachineInstr *MI,
-                                    const SmallVectorImpl<unsigned> &Ops) const;
-
   virtual bool BlockHasNoFallThrough(const MachineBasicBlock &MBB) const;
   virtual
   bool ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const;
@@ -209,9 +195,16 @@ public:
 };
 
 class ARMInstrInfo : public ARMBaseInstrInfo {
+  ARMRegisterInfo RI;
 public:
   explicit ARMInstrInfo(const ARMSubtarget &STI);
 
+  /// getRegisterInfo - TargetInstrInfo is a superset of MRegister info.  As
+  /// such, whenever a client has an instance of instruction info, it should
+  /// always be able to get register info as well (through this method).
+  ///
+  virtual const ARMRegisterInfo &getRegisterInfo() const { return RI; }
+
   /// Return true if the instruction is a register to register move and return
   /// the source and dest operands and their sub-register indices by reference.
   virtual bool isMoveInstr(const MachineInstr &MI,
@@ -248,6 +241,12 @@ public:
                                const TargetRegisterClass *RC,
                                SmallVectorImpl<MachineInstr*> &NewMIs) const;
 
+  void reMaterialize(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
+                     unsigned DestReg, const MachineInstr *Orig) const;
+
+  virtual bool canFoldMemoryOperand(const MachineInstr *MI,
+                                    const SmallVectorImpl<unsigned> &Ops) const;
+
   virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
                                               MachineInstr* MI,
                                            const SmallVectorImpl<unsigned> &Ops,
diff --git a/lib/Target/ARM/ARMRegisterInfo.cpp b/lib/Target/ARM/ARMRegisterInfo.cpp
index bb0cc8ff06..a58e8ec0e0 100644
--- a/lib/Target/ARM/ARMRegisterInfo.cpp
+++ b/lib/Target/ARM/ARMRegisterInfo.cpp
@@ -31,16 +31,9 @@
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/Support/CommandLine.h"
-#include <algorithm>
 using namespace llvm;
 
-static cl::opt<bool> ThumbRegScavenging("enable-thumb-reg-scavenging",
-                               cl::Hidden,
-                               cl::desc("Enable register scavenging on Thumb"));
-
-unsigned ARMRegisterInfo::getRegisterNumbering(unsigned RegEnum) {
+unsigned ARMBaseRegisterInfo::getRegisterNumbering(unsigned RegEnum) {
   using namespace ARM;
   switch (RegEnum) {
   case R0:  case S0:  case D0:  return 0;
@@ -81,8 +74,8 @@ unsigned ARMRegisterInfo::getRegisterNumbering(unsigned RegEnum) {
   }
 }
 
-unsigned ARMRegisterInfo::getRegisterNumbering(unsigned RegEnum,
-                                               bool &isSPVFP) {
+unsigned ARMBaseRegisterInfo::getRegisterNumbering(unsigned RegEnum,
+                                                   bool &isSPVFP) {
   isSPVFP = false;
 
   using namespace ARM;
@@ -108,12 +101,12 @@ unsigned ARMRegisterInfo::getRegisterNumbering(unsigned RegEnum,
   case PC:  case D15: return 15;
 
   case S0: case S1: case S2: case S3:
-  case S4: case S5: case S6: case S7: 
-  case S8: case S9: case S10: case S11: 
-  case S12: case S13: case S14: case S15: 
-  case S16: case S17: case S18: case S19: 
-  case S20: case S21: case S22: case S23: 
-  case S24: case S25: case S26: case S27: 
+  case S4: case S5: case S6: case S7:
+  case S8: case S9: case S10: case S11:
+  case S12: case S13: case S14: case S15:
+  case S16: case S17: case S18: case S19:
+  case S20: case S21: case S22: case S23:
+  case S24: case S25: case S26: case S27:
   case S28: case S29: case S30: case S31:  {
     isSPVFP = true;
     switch (RegEnum) {
@@ -155,13 +148,18 @@ unsigned ARMRegisterInfo::getRegisterNumbering(unsigned RegEnum,
   }
 }
 
-ARMRegisterInfo::ARMRegisterInfo(const TargetInstrInfo &tii,
-                                 const ARMSubtarget &sti)
+ARMBaseRegisterInfo::ARMBaseRegisterInfo(const TargetInstrInfo &tii,
+                                         const ARMSubtarget &sti)
   : ARMGenRegisterInfo(ARM::ADJCALLSTACKDOWN, ARM::ADJCALLSTACKUP),
     TII(tii), STI(sti),
     FramePtr((STI.isTargetDarwin() || STI.isThumb()) ? ARM::R7 : ARM::R11) {
 }
 
+ARMRegisterInfo::ARMRegisterInfo(const TargetInstrInfo &tii,
+                                 const ARMSubtarget &sti)
+  : ARMBaseRegisterInfo(tii, sti) {
+}
+
 static inline
 const MachineInstrBuilder &AddDefaultPred(const MachineInstrBuilder &MIB) {
   return MIB.addImm((int64_t)ARMCC::AL).addReg(0);
@@ -179,24 +177,20 @@ void ARMRegisterInfo::emitLoadConstPool(MachineBasicBlock &MBB,
                                         unsigned DestReg, int Val,
                                         unsigned Pred, unsigned PredReg,
                                         const TargetInstrInfo *TII,
-                                        bool isThumb,
                                         DebugLoc dl) const {
   MachineFunction &MF = *MBB.getParent();
   MachineConstantPool *ConstantPool = MF.getConstantPool();
   Constant *C = ConstantInt::get(Type::Int32Ty, Val);
   unsigned Idx = ConstantPool->getConstantPoolIndex(C, 4);
-  if (isThumb)
-    BuildMI(MBB, MBBI, dl, 
-            TII->get(ARM::tLDRcp),DestReg).addConstantPoolIndex(Idx);
-  else
-    BuildMI(MBB, MBBI, dl, TII->get(ARM::LDRcp), DestReg)
-      .addConstantPoolIndex(Idx)
-      .addReg(0).addImm(0).addImm(Pred).addReg(PredReg);
+
+  BuildMI(MBB, MBBI, dl, TII->get(ARM::LDRcp), DestReg)
+    .addConstantPoolIndex(Idx)
+    .addReg(0).addImm(0).addImm(Pred).addReg(PredReg);
 }
 
 /// isLowRegister - Returns true if the register is low register r0-r7.
 ///
-bool ARMRegisterInfo::isLowRegister(unsigned Reg) const {
+bool ARMBaseRegisterInfo::isLowRegister(unsigned Reg) const {
   using namespace ARM;
   switch (Reg) {
   case R0:  case R1:  case R2:  case R3:
@@ -207,24 +201,8 @@ bool ARMRegisterInfo::isLowRegister(unsigned Reg) const {
   }
 }
 
-const TargetRegisterClass*
-ARMRegisterInfo::getPhysicalRegisterRegClass(unsigned Reg, MVT VT) const {
-  if (STI.isThumb()) {
-    if (isLowRegister(Reg))
-      return ARM::tGPRRegisterClass;
-    switch (Reg) {
-    default:
-      break;
-    case ARM::R8:  case ARM::R9:  case ARM::R10:  case ARM::R11:
-    case ARM::R12: case ARM::SP:  case ARM::LR:   case ARM::PC:
-      return ARM::GPRRegisterClass;
-    }
-  }
-  return TargetRegisterInfo::getPhysicalRegisterRegClass(Reg, VT);
-}
-
 const unsigned*
-ARMRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
+ARMBaseRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
   static const unsigned CalleeSavedRegs[] = {
     ARM::LR, ARM::R11, ARM::R10, ARM::R9, ARM::R8,
     ARM::R7, ARM::R6,  ARM::R5,  ARM::R4,
@@ -248,7 +226,7 @@ ARMRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
 }
 
 const TargetRegisterClass* const *
-ARMRegisterInfo::getCalleeSavedRegClasses(const MachineFunction *MF) const {
+ARMBaseRegisterInfo::getCalleeSavedRegClasses(const MachineFunction *MF) const {
   static const TargetRegisterClass * const CalleeSavedRegClasses[] = {
     &ARM::GPRRegClass, &ARM::GPRRegClass, &ARM::GPRRegClass,
     &ARM::GPRRegClass, &ARM::GPRRegClass, &ARM::GPRRegClass,
@@ -297,7 +275,7 @@ ARMRegisterInfo::getCalleeSavedRegClasses(const MachineFunction *MF) const {
     ? DarwinCalleeSavedRegClasses : CalleeSavedRegClasses;
 }
 
-BitVector ARMRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
+BitVector ARMBaseRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
   // FIXME: avoid re-calculating this everytime.
   BitVector Reserved(getNumRegs());
   Reserved.set(ARM::SP);
@@ -311,7 +289,7 @@ BitVector ARMRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
 }
 
 bool
-ARMRegisterInfo::isReservedReg(const MachineFunction &MF, unsigned Reg) const {
+ARMBaseRegisterInfo::isReservedReg(const MachineFunction &MF, unsigned Reg) const {
   switch (Reg) {
   default: break;
   case ARM::SP:
@@ -329,16 +307,16 @@ ARMRegisterInfo::isReservedReg(const MachineFunction &MF, unsigned Reg) const {
   return false;
 }
 
-const TargetRegisterClass *ARMRegisterInfo::getPointerRegClass() const {
+const TargetRegisterClass *ARMBaseRegisterInfo::getPointerRegClass() const {
   return &ARM::GPRRegClass;
 }
 
 /// getAllocationOrder - Returns the register allocation order for a specified
 /// register class in the form of a pair of TargetRegisterClass iterators.
 std::pair<TargetRegisterClass::iterator,TargetRegisterClass::iterator>
-ARMRegisterInfo::getAllocationOrder(const TargetRegisterClass *RC,
-                                    unsigned HintType, unsigned HintReg,
-                                    const MachineFunction &MF) const {
+ARMBaseRegisterInfo::getAllocationOrder(const TargetRegisterClass *RC,
+                                        unsigned HintType, unsigned HintReg,
+                                        const MachineFunction &MF) const {
   // Alternative register allocation orders when favoring even / odd registers
   // of register pairs.
 
@@ -479,8 +457,8 @@ ARMRegisterInfo::getAllocationOrder(const TargetRegisterClass *RC,
 /// ResolveRegAllocHint - Resolves the specified register allocation hint
 /// to a physical register. Returns the physical register if it is successful.
 unsigned
-ARMRegisterInfo::ResolveRegAllocHint(unsigned Type, unsigned Reg,
-                                     const MachineFunction &MF) const {
+ARMBaseRegisterInfo::ResolveRegAllocHint(unsigned Type, unsigned Reg,
+                                         const MachineFunction &MF) const {
   if (Reg == 0 || !isPhysicalRegister(Reg))
     return 0;
   if (Type == 0)
@@ -495,8 +473,8 @@ ARMRegisterInfo::ResolveRegAllocHint(unsigned Type, unsigned Reg,
 }
 
 void
-ARMRegisterInfo::UpdateRegAllocHint(unsigned Reg, unsigned NewReg,
-                                    MachineFunction &MF) const {
+ARMBaseRegisterInfo::UpdateRegAllocHint(unsigned Reg, unsigned NewReg,
+                                        MachineFunction &MF) const {
   MachineRegisterInfo *MRI = &MF.getRegInfo();
   std::pair<unsigned, unsigned> Hint = MRI->getRegAllocationHint(Reg);
   if ((Hint.first == (unsigned)ARMRI::RegPairOdd ||
@@ -516,15 +494,14 @@ ARMRegisterInfo::UpdateRegAllocHint(unsigned Reg, unsigned NewReg,
 
 bool
 ARMRegisterInfo::requiresRegisterScavenging(const MachineFunction &MF) const {
-  const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
-  return ThumbRegScavenging || !AFI->isThumbFunction();
+  return true;
 }
 
 /// hasFP - Return true if the specified function should have a dedicated frame
 /// pointer register.  This is true if the function has variable sized allocas
 /// or if frame pointer elimination is disabled.
 ///
-bool ARMRegisterInfo::hasFP(const MachineFunction &MF) const {
+bool ARMBaseRegisterInfo::hasFP(const MachineFunction &MF) const {
   const MachineFrameInfo *MFI = MF.getFrameInfo();
   return (NoFramePointerElim ||
           MFI->hasVarSizedObjects() ||
@@ -539,18 +516,13 @@ bool ARMRegisterInfo::hasFP(const MachineFunction &MF) const {
 bool ARMRegisterInfo::hasReservedCallFrame(MachineFunction &MF) const {
   const MachineFrameInfo *FFI = MF.getFrameInfo();
   unsigned CFSize = FFI->getMaxCallFrameSize();
-  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
   // It's not always a good idea to include the call frame as part of the
   // stack frame. ARM (especially Thumb) has small immediate offset to
   // address the stack frame. So a large call frame can cause poor codegen
   // and may even makes it impossible to scavenge a register.
-  if (AFI->isThumbFunction()) {
-    if (CFSize >= ((1 << 8) - 1) * 4 / 2) // Half of imm8 * 4
-      return false;
-  } else {
-    if (CFSize >= ((1 << 12) - 1) / 2)  // Half of imm12
-      return false;
-  }
+  if (CFSize >= ((1 << 12) - 1) / 2)  // Half of imm12
+    return false;
+
   return !MF.getFrameInfo()->hasVarSizedObjects();
 }
 
@@ -570,14 +542,14 @@ void emitARMRegPlusImmediate(MachineBasicBlock &MBB,
     unsigned RotAmt = ARM_AM::getSOImmValRotate(NumBytes);
     unsigned ThisVal = NumBytes & ARM_AM::rotr32(0xFF, RotAmt);
     assert(ThisVal && "Didn't extract field correctly");
-    
+
     // We will handle these bits from offset, clear them.
     NumBytes &= ~ThisVal;
-    
+
     // Get the properly encoded SOImmVal field.
     int SOImmVal = ARM_AM::getSOImmVal(ThisVal);
     assert(SOImmVal != -1 && "Bit extraction didn't work?");
-    
+
     // Build the new ADD / SUB.
     BuildMI(MBB, MBBI, dl, TII.get(isSub ? ARM::SUBri : ARM::ADDri), DestReg)
       .addReg(BaseReg, RegState::Kill).addImm(SOImmVal)
@@ -586,204 +558,12 @@ void emitARMRegPlusImmediate(MachineBasicBlock &MBB,
   }
 }
 
-/// calcNumMI - Returns the number of instructions required to materialize
-/// the specific add / sub r, c instruction.
-static unsigned calcNumMI(int Opc, int ExtraOpc, unsigned Bytes,
-                          unsigned NumBits, unsigned Scale) {
-  unsigned NumMIs = 0;
-  unsigned Chunk = ((1 << NumBits) - 1) * Scale;
-
-  if (Opc == ARM::tADDrSPi) {
-    unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
-    Bytes -= ThisVal;
-    NumMIs++;
-    NumBits = 8;
-    Scale = 1;  // Followed by a number of tADDi8.
-    Chunk = ((1 << NumBits) - 1) * Scale;
-  }
-
-  NumMIs += Bytes / Chunk;
-  if ((Bytes % Chunk) != 0)
-    NumMIs++;
-  if (ExtraOpc)
-    NumMIs++;
-  return NumMIs;
-}
-
-/// emitThumbRegPlusImmInReg - Emits a series of instructions to materialize
-/// a destreg = basereg + immediate in Thumb code. Materialize the immediate
-/// in a register using mov / mvn sequences or load the immediate from a
-/// constpool entry.
-static
-void emitThumbRegPlusImmInReg(MachineBasicBlock &MBB,
-                              MachineBasicBlock::iterator &MBBI,
-                              unsigned DestReg, unsigned BaseReg,
-                              int NumBytes, bool CanChangeCC,
-                              const TargetInstrInfo &TII,
-                              const ARMRegisterInfo& MRI,
-                              DebugLoc dl) {
-    bool isHigh = !MRI.isLowRegister(DestReg) ||
-                  (BaseReg != 0 && !MRI.isLowRegister(BaseReg));
-    bool isSub = false;
-    // Subtract doesn't have high register version. Load the negative value
-    // if either base or dest register is a high register. Also, if do not
-    // issue sub as part of the sequence if condition register is to be
-    // preserved.
-    if (NumBytes < 0 && !isHigh && CanChangeCC) {
-      isSub = true;
-      NumBytes = -NumBytes;
-    }
-    unsigned LdReg = DestReg;
-    if (DestReg == ARM::SP) {
-      assert(BaseReg == ARM::SP && "Unexpected!");
-      LdReg = ARM::R3;
-      BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVlor2hir), ARM::R12)
-        .addReg(ARM::R3, RegState::Kill);
-    }
-
-    if (NumBytes <= 255 && NumBytes >= 0)
-      BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVi8), LdReg).addImm(NumBytes);
-    else if (NumBytes < 0 && NumBytes >= -255) {
-      BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVi8), LdReg).addImm(NumBytes);
-      BuildMI(MBB, MBBI, dl, TII.get(ARM::tNEG), LdReg)
-        .addReg(LdReg, RegState::Kill);
-    } else
-      MRI.emitLoadConstPool(MBB, MBBI, LdReg, NumBytes, ARMCC::AL, 0, &TII, 
-                            true, dl);
-
-    // Emit add / sub.
-    int Opc = (isSub) ? ARM::tSUBrr : (isHigh ? ARM::tADDhirr : ARM::tADDrr);
-    const MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, 
-                                            TII.get(Opc), DestReg);
-    if (DestReg == ARM::SP || isSub)
-      MIB.addReg(BaseReg).addReg(LdReg, RegState::Kill);
-    else
-      MIB.addReg(LdReg).addReg(BaseReg, RegState::Kill);
-    if (DestReg == ARM::SP)
-      BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVhir2lor), ARM::R3)
-        .addReg(ARM::R12, RegState::Kill);
-}
-
-/// emitThumbRegPlusImmediate - Emits a series of instructions to materialize
-/// a destreg = basereg + immediate in Thumb code.
-static
-void emitThumbRegPlusImmediate(MachineBasicBlock &MBB,
-                               MachineBasicBlock::iterator &MBBI,
-                               unsigned DestReg, unsigned BaseReg,
-                               int NumBytes, const TargetInstrInfo &TII,
-                               const ARMRegisterInfo& MRI,
-                               DebugLoc dl) {
-  bool isSub = NumBytes < 0;
-  unsigned Bytes = (unsigned)NumBytes;
-  if (isSub) Bytes = -NumBytes;
-  bool isMul4 = (Bytes & 3) == 0;
-  bool isTwoAddr = false;
-  bool DstNotEqBase = false;
-  unsigned NumBits = 1;
-  unsigned Scale = 1;
-  int Opc = 0;
-  int ExtraOpc = 0;
-
-  if (DestReg == BaseReg && BaseReg == ARM::SP) {
-    assert(isMul4 && "Thumb sp inc / dec size must be multiple of 4!");
-    NumBits = 7;
-    Scale = 4;
-    Opc = isSub ? ARM::tSUBspi : ARM::tADDspi;
-    isTwoAddr = true;
-  } else if (!isSub && BaseReg == ARM::SP) {
-    // r1 = add sp, 403
-    // =>
-    // r1 = add sp, 100 * 4
-    // r1 = add r1, 3
-    if (!isMul4) {
-      Bytes &= ~3;
-      ExtraOpc = ARM::tADDi3;
-    }
-    NumBits = 8;
-    Scale = 4;
-    Opc = ARM::tADDrSPi;
-  } else {
-    // sp = sub sp, c
-    // r1 = sub sp, c
-    // r8 = sub sp, c
-    if (DestReg != BaseReg)
-      DstNotEqBase = true;
-    NumBits = 8;
-    Opc = isSub ? ARM::tSUBi8 : ARM::tADDi8;
-    isTwoAddr = true;
-  }
-
-  unsigned NumMIs = calcNumMI(Opc, ExtraOpc, Bytes, NumBits, Scale);
-  unsigned Threshold = (DestReg == ARM::SP) ? 3 : 2;
-  if (NumMIs > Threshold) {
-    // This will expand into too many instructions. Load the immediate from a
-    // constpool entry.
-    emitThumbRegPlusImmInReg(MBB, MBBI, DestReg, BaseReg, NumBytes, true, TII,
-                             MRI, dl);
-    return;
-  }
-
-  if (DstNotEqBase) {
-    if (MRI.isLowRegister(DestReg) && MRI.isLowRegister(BaseReg)) {
-      // If both are low registers, emit DestReg = add BaseReg, max(Imm, 7)
-      unsigned Chunk = (1 << 3) - 1;
-      unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
-      Bytes -= ThisVal;
-      BuildMI(MBB, MBBI, dl,TII.get(isSub ? ARM::tSUBi3 : ARM::tADDi3), DestReg)
-        .addReg(BaseReg, RegState::Kill).addImm(ThisVal);
-    } else {
-      BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), DestReg)
-        .addReg(BaseReg, RegState::Kill);
-    }
-    BaseReg = DestReg;
-  }
-
-  unsigned Chunk = ((1 << NumBits) - 1) * Scale;
-  while (Bytes) {
-    unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
-    Bytes -= ThisVal;
-    ThisVal /= Scale;
-    // Build the new tADD / tSUB.
-    if (isTwoAddr)
-      BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
-        .addReg(DestReg).addImm(ThisVal);
-    else {
-      bool isKill = BaseReg != ARM::SP;
-      BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
-        .addReg(BaseReg, getKillRegState(isKill)).addImm(ThisVal);
-      BaseReg = DestReg;
-
-      if (Opc == ARM::tADDrSPi) {
-        // r4 = add sp, imm
-        // r4 = add r4, imm
-        // ...
-        NumBits = 8;
-        Scale = 1;
-        Chunk = ((1 << NumBits) - 1) * Scale;
-        Opc = isSub ? ARM::tSUBi8 : ARM::tADDi8;
-        isTwoAddr = true;
-      }
-    }
-  }
-
-  if (ExtraOpc)
-    BuildMI(MBB, MBBI, dl, TII.get(ExtraOpc), DestReg)
-      .addReg(DestReg, RegState::Kill)
-      .addImm(((unsigned)NumBytes) & 3);
-}
-
-static
-void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
-                  int NumBytes, ARMCC::CondCodes Pred, unsigned PredReg,
-                  bool isThumb, const TargetInstrInfo &TII, 
-                  const ARMRegisterInfo& MRI,
-                  DebugLoc dl) {
-  if (isThumb)
-    emitThumbRegPlusImmediate(MBB, MBBI, ARM::SP, ARM::SP, NumBytes, TII,
-                              MRI, dl);
-  else
-    emitARMRegPlusImmediate(MBB, MBBI, ARM::SP, ARM::SP, NumBytes,
-                            Pred, PredReg, TII, dl);
+void ARMRegisterInfo::
+emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
+             int NumBytes, ARMCC::CondCodes Pred, unsigned PredReg,
+             const TargetInstrInfo &TII, DebugLoc dl) const {
+  emitARMRegPlusImmediate(MBB, MBBI, ARM::SP, ARM::SP, NumBytes,
+                          Pred, PredReg, TII, dl);
 }
 
 void ARMRegisterInfo::
@@ -797,7 +577,6 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
     DebugLoc dl = Old->getDebugLoc();
     unsigned Amount = Old->getOperand(0).getImm();
     if (Amount != 0) {
-      ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
       // We need to keep the stack aligned properly.  To do this, we round the
       // amount of space needed for the outgoing arguments up to the next
       // alignment boundary.
@@ -806,46 +585,22 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
 
       // Replace the pseudo instruction with a new instruction...
       unsigned Opc = Old->getOpcode();
-      bool isThumb = AFI->isThumbFunction();
-      ARMCC::CondCodes Pred = isThumb
-        ? ARMCC::AL : (ARMCC::CondCodes)Old->getOperand(1).getImm();
+      ARMCC::CondCodes Pred = (ARMCC::CondCodes)Old->getOperand(1).getImm();
       if (Opc == ARM::ADJCALLSTACKDOWN || Opc == ARM::tADJCALLSTACKDOWN) {
         // Note: PredReg is operand 2 for ADJCALLSTACKDOWN.
-        unsigned PredReg = isThumb ? 0 : Old->getOperand(2).getReg();
-        emitSPUpdate(MBB, I, -Amount, Pred, PredReg, isThumb, TII, *this, dl);
+        unsigned PredReg = Old->getOperand(2).getReg();
+        emitSPUpdate(MBB, I, -Amount, Pred, PredReg, TII, dl);
       } else {
         // Note: PredReg is operand 3 for ADJCALLSTACKUP.
-        unsigned PredReg = isThumb ? 0 : Old->getOperand(3).getReg();
+        unsigned PredReg = Old->getOperand(3).getReg();
         assert(Opc == ARM::ADJCALLSTACKUP || Opc == ARM::tADJCALLSTACKUP);
-        emitSPUpdate(MBB, I, Amount, Pred, PredReg, isThumb, TII, *this, dl);
+        emitSPUpdate(MBB, I, Amount, Pred, PredReg, TII, dl);
       }
     }
   }
   MBB.erase(I);
 }
 
-/// emitThumbConstant - Emit a series of instructions to materialize a
-/// constant.
-static void emitThumbConstant(MachineBasicBlock &MBB,
-                              MachineBasicBlock::iterator &MBBI,
-                              unsigned DestReg, int Imm,
-                              const TargetInstrInfo &TII,
-                              const ARMRegisterInfo& MRI,
-                              DebugLoc dl) {
-  bool isSub = Imm < 0;
-  if (isSub) Imm = -Imm;
-
-  int Chunk = (1 << 8) - 1;
-  int ThisVal = (Imm > Chunk) ? Chunk : Imm;
-  Imm -= ThisVal;
-  BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVi8), DestReg).addImm(ThisVal);
-  if (Imm > 0) 
-    emitThumbRegPlusImmediate(MBB, MBBI, DestReg, DestReg, Imm, TII, MRI, dl);
-  if (isSub)
-    BuildMI(MBB, MBBI, dl, TII.get(ARM::tNEG), DestReg)
-      .addReg(DestReg, RegState::Kill);
-}
-
 /// findScratchRegister - Find a 'free' ARM register. If register scavenger
 /// is not being used, R12 is available. Otherwise, try for a call-clobbered
 /// register first and then a spilled callee-saved register if that fails.
@@ -868,17 +623,16 @@ void ARMRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
   MachineBasicBlock &MBB = *MI.getParent();
   MachineFunction &MF = *MBB.getParent();
   ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
-  bool isThumb = AFI->isThumbFunction();
   DebugLoc dl = MI.getDebugLoc();
 
   while (!MI.getOperand(i).isFI()) {
     ++i;
     assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
   }
-  
+
   unsigned FrameReg = ARM::SP;
   int FrameIndex = MI.getOperand(i).getIndex();
-  int Offset = MF.getFrameInfo()->getObjectOffset(FrameIndex) + 
+  int Offset = MF.getFrameInfo()->getObjectOffset(FrameIndex) +
                MF.getFrameInfo()->getStackSize() + SPAdj;
 
   if (AFI->isGPRCalleeSavedArea1Frame(FrameIndex))
@@ -926,86 +680,20 @@ void ARMRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
       MI.getOperand(i+1).ChangeToImmediate(ImmedOffset);
       return;
     }
-    
+
     // Otherwise, we fallback to common code below to form the imm offset with
     // a sequence of ADDri instructions.  First though, pull as much of the imm
     // into this ADDri as possible.
     unsigned RotAmt = ARM_AM::getSOImmValRotate(Offset);
     unsigned ThisImmVal = Offset & ARM_AM::rotr32(0xFF, RotAmt);
-    
+
     // We will handle these bits from offset, clear them.
     Offset &= ~ThisImmVal;
-    
+
     // Get the properly encoded SOImmVal field.
     int ThisSOImmVal = ARM_AM::getSOImmVal(ThisImmVal);
-    assert(ThisSOImmVal != -1 && "Bit extraction didn't work?");    
+    assert(ThisSOImmVal != -1 && "Bit extraction didn't work?");
     MI.getOperand(i+1).ChangeToImmediate(ThisSOImmVal);
-  } else if (Opcode == ARM::tADDrSPi) {
-    Offset += MI.getOperand(i+1).getImm();
-
-    // Can't use tADDrSPi if it's based off the frame pointer.
-    unsigned NumBits = 0;
-    unsigned Scale = 1;
-    if (FrameReg != ARM::SP) {
-      Opcode = ARM::tADDi3;
-      MI.setDesc(TII.get(ARM::tADDi3));
-      NumBits = 3;
-    } else {
-      NumBits = 8;
-      Scale = 4;
-      assert((Offset & 3) == 0 &&
-             "Thumb add/sub sp, #imm immediate must be multiple of 4!");
-    }
-
-    if (Offset == 0) {
-      // Turn it into a move.
-      MI.setDesc(TII.get(ARM::tMOVhir2lor));
-      MI.getOperand(i).ChangeToRegister(FrameReg, false);
-      MI.RemoveOperand(i+1);
-      return;
-    }
-
-    // Common case: small offset, fits into instruction.
-    unsigned Mask = (1 << NumBits) - 1;
-    if (((Offset / Scale) & ~Mask) == 0) {
-      // Replace the FrameIndex with sp / fp
-      MI.getOperand(i).ChangeToRegister(FrameReg, false);
-      MI.getOperand(i+1).ChangeToImmediate(Offset / Scale);
-      return;
-    }
-
-    unsigned DestReg = MI.getOperand(0).getReg();
-    unsigned Bytes = (Offset > 0) ? Offset : -Offset;
-    unsigned NumMIs = calcNumMI(Opcode, 0, Bytes, NumBits, Scale);
-    // MI would expand into a large number of instructions. Don't try to
-    // simplify the immediate.
-    if (NumMIs > 2) {
-      emitThumbRegPlusImmediate(MBB, II, DestReg, FrameReg, Offset, TII,
-                                *this, dl);
-      MBB.erase(II);
-      return;
-    }
-
-    if (Offset > 0) {
-      // Translate r0 = add sp, imm to
-      // r0 = add sp, 255*4
-      // r0 = add r0, (imm - 255*4)
-      MI.getOperand(i).ChangeToRegister(FrameReg, false);
-      MI.getOperand(i+1).ChangeToImmediate(Mask);
-      Offset = (Offset - Mask * Scale);
-      MachineBasicBlock::iterator NII = next(II);
-      emitThumbRegPlusImmediate(MBB, NII, DestReg, DestReg, Offset, TII,
-                                *this, dl);
-    } else {
-      // Translate r0 = add sp, -imm to
-      // r0 = -imm (this is then translated into a series of instructons)
-      // r0 = add r0, sp
-      emitThumbConstant(MBB, II, DestReg, Offset, TII, *this, dl);
-      MI.setDesc(TII.get(ARM::tADDhirr));
-      MI.getOperand(i).ChangeToRegister(DestReg, false, false, true);
-      MI.getOperand(i+1).ChangeToRegister(FrameReg, false);
-    }
-    return;
   } else {
     unsigned ImmIdx = 0;
     int InstrOffs = 0;
@@ -1037,13 +725,6 @@ void ARMRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
       Scale = 4;
       break;
     }
-    case ARMII::AddrModeTs: {
-      ImmIdx = i+1;
-      InstrOffs = MI.getOperand(ImmIdx).getImm();
-      NumBits = (FrameReg == ARM::SP) ? 8 : 5;
-      Scale = 4;
-      break;
-    }
     default:
       assert(0 && "Unsupported addressing mode!");
       abort();
@@ -1052,7 +733,7 @@ void ARMRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
 
     Offset += InstrOffs * Scale;
     assert((Offset & (Scale-1)) == 0 && "Can't encode this offset!");
-    if (Offset < 0 && !isThumb) {
+    if (Offset < 0) {
       Offset = -Offset;
       isSub = true;
     }
@@ -1070,121 +751,34 @@ void ARMRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
       return;
     }
 
-    bool isThumSpillRestore = Opcode == ARM::tRestore || Opcode == ARM::tSpill;
-    if (AddrMode == ARMII::AddrModeTs) {
-      // Thumb tLDRspi, tSTRspi. These will change to instructions that use
-      // a different base register.
-      NumBits = 5;
-      Mask = (1 << NumBits) - 1;
-    }
-    // If this is a thumb spill / restore, we will be using a constpool load to
-    // materialize the offset.
-    if (AddrMode == ARMII::AddrModeTs && isThumSpillRestore)
-      ImmOp.ChangeToImmediate(0);
-    else {
-      // Otherwise, it didn't fit. Pull in what we can to simplify the immed.
-      ImmedOffset = ImmedOffset & Mask;
-      if (isSub)
-        ImmedOffset |= 1 << NumBits;
-      ImmOp.ChangeToImmediate(ImmedOffset);
-      Offset &= ~(Mask*Scale);
-    }
+    // Otherwise, it didn't fit. Pull in what we can to simplify the immed.
+    ImmedOffset = ImmedOffset & Mask;
+    if (isSub)
+      ImmedOffset |= 1 << NumBits;
+    ImmOp.ChangeToImmediate(ImmedOffset);
+    Offset &= ~(Mask*Scale);
   }
-  
+
   // If we get here, the immediate doesn't fit into the instruction.  We folded
   // as much as possible above, handle the rest, providing a register that is
   // SP+LargeImm.
   assert(Offset && "This code isn't needed if offset already handled!");
 
-  if (isThumb) {
-    if (Desc.mayLoad()) {
-      // Use the destination register to materialize sp + offset.
-      unsigned TmpReg = MI.getOperand(0).getReg();
-      bool UseRR = false;
-      if (Opcode == ARM::tRestore) {
-        if (FrameReg == ARM::SP)
-          emitThumbRegPlusImmInReg(MBB, II, TmpReg, FrameReg,
-                                   Offset, false, TII, *this, dl);
-        else {
-          emitLoadConstPool(MBB, II, TmpReg, Offset, ARMCC::AL, 0, &TII,
-                            true, dl);
-          UseRR = true;
-        }
-      } else
-        emitThumbRegPlusImmediate(MBB, II, TmpReg, FrameReg, Offset, TII,
-                                  *this, dl);
-      MI.setDesc(TII.get(ARM::tLDR));
-      MI.getOperand(i).ChangeToRegister(TmpReg, false, false, true);
-      if (UseRR)
-        // Use [reg, reg] addrmode.
-        MI.addOperand(MachineOperand::CreateReg(FrameReg, false));
-      else  // tLDR has an extra register operand.
-        MI.addOperand(MachineOperand::CreateReg(0, false));
-    } else if (Desc.mayStore()) {
-      // FIXME! This is horrific!!! We need register scavenging.
-      // Our temporary workaround has marked r3 unavailable. Of course, r3 is
-      // also a ABI register so it's possible that is is the register that is
-      // being storing here. If that's the case, we do the following:
-      // r12 = r2
-      // Use r2 to materialize sp + offset
-      // str r3, r2
-      // r2 = r12
-      unsigned ValReg = MI.getOperand(0).getReg();
-      unsigned TmpReg = ARM::R3;
-      bool UseRR = false;
-      if (ValReg == ARM::R3) {
-        BuildMI(MBB, II, dl, TII.get(ARM::tMOVlor2hir), ARM::R12)
-          .addReg(ARM::R2, RegState::Kill);
-        TmpReg = ARM::R2;
-      }
-      if (TmpReg == ARM::R3 && AFI->isR3LiveIn())
-        BuildMI(MBB, II, dl, TII.get(ARM::tMOVlor2hir), ARM::R12)
-          .addReg(ARM::R3, RegState::Kill);
-      if (Opcode == ARM::tSpill) {
-        if (FrameReg == ARM::SP)
-          emitThumbRegPlusImmInReg(MBB, II, TmpReg, FrameReg,
-                                   Offset, false, TII, *this, dl);
-        else {
-          emitLoadConstPool(MBB, II, TmpReg, Offset, ARMCC::AL, 0, &TII,
-                            true, dl);
-          UseRR = true;
-        }
-      } else
-        emitThumbRegPlusImmediate(MBB, II, TmpReg, FrameReg, Offset, TII,
-                                  *this, dl);
-      MI.setDesc(TII.get(ARM::tSTR));
-      MI.getOperand(i).ChangeToRegister(TmpReg, false, false, true);
-      if (UseRR)  // Use [reg, reg] addrmode.
-        MI.addOperand(MachineOperand::CreateReg(FrameReg, false));
-      else // tSTR has an extra register operand.
-        MI.addOperand(MachineOperand::CreateReg(0, false));
-
-      MachineBasicBlock::iterator NII = next(II);
-      if (ValReg == ARM::R3)
-        BuildMI(MBB, NII, dl, TII.get(ARM::tMOVhir2lor), ARM::R2)
-          .addReg(ARM::R12, RegState::Kill);
-      if (TmpReg == ARM::R3 && AFI->isR3LiveIn())
-        BuildMI(MBB, NII, dl, TII.get(ARM::tMOVhir2lor), ARM::R3)
-          .addReg(ARM::R12, RegState::Kill);
-    } else
-      assert(false && "Unexpected opcode!");
-  } else {
-    // Insert a set of r12 with the full address: r12 = sp + offset
-    // If the offset we have is too large to fit into the instruction, we need
-    // to form it with a series of ADDri's.  Do this by taking 8-bit chunks
-    // out of 'Offset'.
-    unsigned ScratchReg = findScratchRegister(RS, &ARM::GPRRegClass, AFI);
-    if (ScratchReg == 0)
-      // No register is "free". Scavenge a register.
-      ScratchReg = RS->scavengeRegister(&ARM::GPRRegClass, II, SPAdj);
-    int PIdx = MI.findFirstPredOperandIdx();
-    ARMCC::CondCodes Pred = (PIdx == -1)
-      ? ARMCC::AL : (ARMCC::CondCodes)MI.getOperand(PIdx).getImm();
-    unsigned PredReg = (PIdx == -1) ? 0 : MI.getOperand(PIdx+1).getReg();
-    emitARMRegPlusImmediate(MBB, II, ScratchReg, FrameReg,
-                            isSub ? -Offset : Offset, Pred, PredReg, TII, dl);
-    MI.getOperand(i).ChangeToRegister(ScratchReg, false, false, true);
-  }
+  // Insert a set of r12 with the full address: r12 = sp + offset
+  // If the offset we have is too large to fit into the instruction, we need
+  // to form it with a series of ADDri's.  Do this by taking 8-bit chunks
+  // out of 'Offset'.
+  unsigned ScratchReg = findScratchRegister(RS, &ARM::GPRRegClass, AFI);
+  if (ScratchReg == 0)
+    // No register is "free". Scavenge a register.
+    ScratchReg = RS->scavengeRegister(&ARM::GPRRegClass, II, SPAdj);
+  int PIdx = MI.findFirstPredOperandIdx();
+  ARMCC::CondCodes Pred = (PIdx == -1)
+    ? ARMCC::AL : (ARMCC::CondCodes)MI.getOperand(PIdx).getImm();
+  unsigned PredReg = (PIdx == -1) ? 0 : MI.getOperand(PIdx+1).getReg();
+  emitARMRegPlusImmediate(MBB, II, ScratchReg, FrameReg,
+                          isSub ? -Offset : Offset, Pred, PredReg, TII, dl);
+  MI.getOperand(i).ChangeToRegister(ScratchReg, false, false, true);
 }
 
 static unsigned estimateStackSize(MachineFunction &MF, MachineFrameInfo *MFI) {
@@ -1206,8 +800,8 @@ static unsigned estimateStackSize(MachineFunction &MF, MachineFrameInfo *MFI) {
 }
 
 void
-ARMRegisterInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
-                                                      RegScavenger *RS) const {
+ARMBaseRegisterInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
+                                                          RegScavenger *RS) const {
   // This tells PEI to spill the FP as if it is any other callee-save register
   // to take advantage the eliminateFrameIndex machinery. This also ensures it
   // is spilled in the order specified by getCalleeSavedRegs() to make it easier
@@ -1266,7 +860,7 @@ ARMRegisterInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
         default:
           break;
         }
-      } else { 
+      } else {
         if (!STI.isTargetDarwin()) {
           UnspilledCS1GPRs.push_back(Reg);
           continue;
@@ -1460,40 +1054,23 @@ void ARMRegisterInfo::emitPrologue(MachineFunction &MF) const {
   MachineBasicBlock::iterator MBBI = MBB.begin();
   MachineFrameInfo  *MFI = MF.getFrameInfo();
   ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
-  bool isThumb = AFI->isThumbFunction();
   unsigned VARegSaveSize = AFI->getVarArgsRegSaveSize();
   unsigned NumBytes = MFI->getStackSize();
   const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
   DebugLoc dl = (MBBI != MBB.end() ?
                  MBBI->getDebugLoc() : DebugLoc::getUnknownLoc());
 
-  if (isThumb) {
-    // Check if R3 is live in. It might have to be used as a scratch register.
-    for (MachineRegisterInfo::livein_iterator I =MF.getRegInfo().livein_begin(),
-         E = MF.getRegInfo().livein_end(); I != E; ++I) {
-      if (I->first == ARM::R3) {
-        AFI->setR3IsLiveIn(true);
-        break;
-      }
-    }
-
-    // Thumb add/sub sp, imm8 instructions implicitly multiply the offset by 4.
-    NumBytes = (NumBytes + 3) & ~3;
-    MFI->setStackSize(NumBytes);
-  }
-
   // Determine the sizes of each callee-save spill areas and record which frame
   // belongs to which callee-save spill areas.
   unsigned GPRCS1Size = 0, GPRCS2Size = 0, DPRCSSize = 0;
   int FramePtrSpillFI = 0;
 
   if (VARegSaveSize)
-    emitSPUpdate(MBB, MBBI, -VARegSaveSize, ARMCC::AL, 0, isThumb, TII,
-                 *this, dl);
+    emitSPUpdate(MBB, MBBI, -VARegSaveSize, ARMCC::AL, 0, TII, dl);
 
   if (!AFI->hasStackFrame()) {
     if (NumBytes != 0)
-      emitSPUpdate(MBB, MBBI, -NumBytes, ARMCC::AL, 0, isThumb, TII, *this, dl);
+      emitSPUpdate(MBB, MBBI, -NumBytes, ARMCC::AL, 0, TII, dl);
     return;
   }
 
@@ -1531,34 +1108,25 @@ void ARMRegisterInfo::emitPrologue(MachineFunction &MF) const {
     }
   }
 
-  if (!isThumb) {
-    // Build the new SUBri to adjust SP for integer callee-save spill area 1.
-    emitSPUpdate(MBB, MBBI, -GPRCS1Size, ARMCC::AL, 0, isThumb, TII, *this, dl);
-    movePastCSLoadStoreOps(MBB, MBBI, ARM::STR, 1, STI);
-  } else if (MBBI != MBB.end() && MBBI->getOpcode() == ARM::tPUSH) {
-    ++MBBI;
-    if (MBBI != MBB.end())
-      dl = MBBI->getDebugLoc();
-  }
+  // Build the new SUBri to adjust SP for integer callee-save spill area 1.
+  emitSPUpdate(MBB, MBBI, -GPRCS1Size, ARMCC::AL, 0, TII, dl);
+  movePastCSLoadStoreOps(MBB, MBBI, ARM::STR, 1, STI);
 
   // Darwin ABI requires FP to point to the stack slot that contains the
   // previous FP.
   if (STI.isTargetDarwin() || hasFP(MF)) {
     MachineInstrBuilder MIB =
-      BuildMI(MBB, MBBI, dl, TII.get(isThumb ? ARM::tADDrSPi : ARM::ADDri), 
-              FramePtr)
+      BuildMI(MBB, MBBI, dl, TII.get(ARM::ADDri), FramePtr)
       .addFrameIndex(FramePtrSpillFI).addImm(0);
-    if (!isThumb) AddDefaultCC(AddDefaultPred(MIB));
+    AddDefaultCC(AddDefaultPred(MIB));
   }
 
-  if (!isThumb) {
-    // Build the new SUBri to adjust SP for integer callee-save spill area 2.
-    emitSPUpdate(MBB, MBBI, -GPRCS2Size, ARMCC::AL, 0, false, TII, *this, dl);
+  // Build the new SUBri to adjust SP for integer callee-save spill area 2.
+  emitSPUpdate(MBB, MBBI, -GPRCS2Size, ARMCC::AL, 0, TII, dl);
 
-    // Build the new SUBri to adjust SP for FP callee-save spill area.
-    movePastCSLoadStoreOps(MBB, MBBI, ARM::STR, 2, STI);
-    emitSPUpdate(MBB, MBBI, -DPRCSSize, ARMCC::AL, 0, false, TII, *this, dl);
-  }
+  // Build the new SUBri to adjust SP for FP callee-save spill area.
+  movePastCSLoadStoreOps(MBB, MBBI, ARM::STR, 2, STI);
+  emitSPUpdate(MBB, MBBI, -DPRCSSize, ARMCC::AL, 0, TII, dl);
 
   // Determine starting offsets of spill areas.
   unsigned DPRCSOffset  = NumBytes - (GPRCS1Size + GPRCS2Size + DPRCSSize);
@@ -1568,16 +1136,15 @@ void ARMRegisterInfo::emitPrologue(MachineFunction &MF) const {
   AFI->setGPRCalleeSavedArea1Offset(GPRCS1Offset);
   AFI->setGPRCalleeSavedArea2Offset(GPRCS2Offset);
   AFI->setDPRCalleeSavedAreaOffset(DPRCSOffset);
-  
+
   NumBytes = DPRCSOffset;
   if (NumBytes) {
     // Insert it after all the callee-save spills.
-    if (!isThumb)
-      movePastCSLoadStoreOps(MBB, MBBI, ARM::FSTD, 3, STI);
-    emitSPUpdate(MBB, MBBI, -NumBytes, ARMCC::AL, 0, isThumb, TII, *this, dl);
+    movePastCSLoadStoreOps(MBB, MBBI, ARM::FSTD, 3, STI);
+    emitSPUpdate(MBB, MBBI, -NumBytes, ARMCC::AL, 0, TII, dl);
   }
 
-  if(STI.isTargetELF() && hasFP(MF)) {
+  if (STI.isTargetELF() && hasFP(MF)) {
     MFI->setOffsetAdjustment(MFI->getOffsetAdjustment() -
                              AFI->getFramePtrSpillOffset());
   }
@@ -1596,8 +1163,7 @@ static bool isCalleeSavedRegister(unsigned Reg, const unsigned *CSRegs) {
 
 static bool isCSRestore(MachineInstr *MI, const unsigned *CSRegs) {
   return ((MI->getOpcode() == ARM::FLDD ||
-           MI->getOpcode() == ARM::LDR  ||
-           MI->getOpcode() == ARM::tRestore) &&
+           MI->getOpcode() == ARM::LDR) &&
           MI->getOperand(1).isFI() &&
           isCalleeSavedRegister(MI->getOperand(0).getReg(), CSRegs));
 }
@@ -1605,20 +1171,17 @@ static bool isCSRestore(MachineInstr *MI, const unsigned *CSRegs) {
 void ARMRegisterInfo::emitEpilogue(MachineFunction &MF,
                                    MachineBasicBlock &MBB) const {
   MachineBasicBlock::iterator MBBI = prior(MBB.end());
-  assert((MBBI->getOpcode() == ARM::BX_RET ||
-          MBBI->getOpcode() == ARM::tBX_RET ||
-          MBBI->getOpcode() == ARM::tPOP_RET) &&
+  assert(MBBI->getOpcode() == ARM::BX_RET &&
          "Can only insert epilog into returning blocks");
   DebugLoc dl = MBBI->getDebugLoc();
   MachineFrameInfo *MFI = MF.getFrameInfo();
   ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
-  bool isThumb = AFI->isThumbFunction();
   unsigned VARegSaveSize = AFI->getVarArgsRegSaveSize();
   int NumBytes = (int)MFI->getStackSize();
 
   if (!AFI->hasStackFrame()) {
     if (NumBytes != 0)
-      emitSPUpdate(MBB, MBBI, NumBytes, ARMCC::AL, 0, isThumb, TII, *this, dl);
+      emitSPUpdate(MBB, MBBI, NumBytes, ARMCC::AL, 0, TII, dl);
   } else {
     // Unwind MBBI to point to first LDR / FLDD.
     const unsigned *CSRegs = getCalleeSavedRegs();
@@ -1634,110 +1197,76 @@ void ARMRegisterInfo::emitEpilogue(MachineFunction &MF,
     NumBytes -= (AFI->getGPRCalleeSavedArea1Size() +
                  AFI->getGPRCalleeSavedArea2Size() +
                  AFI->getDPRCalleeSavedAreaSize());
-    if (isThumb) {
-      if (hasFP(MF)) {
-        NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
-        // Reset SP based on frame pointer only if the stack frame extends beyond
-        // frame pointer stack slot or target is ELF and the function has FP.
+
+    // Darwin ABI requires FP to point to the stack slot that contains the
+    // previous FP.
+    if ((STI.isTargetDarwin() && NumBytes) || hasFP(MF)) {
+      NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
+      // Reset SP based on frame pointer only if the stack frame extends beyond
+      // frame pointer stack slot or target is ELF and the function has FP.
+      if (AFI->getGPRCalleeSavedArea2Size() ||
+          AFI->getDPRCalleeSavedAreaSize()  ||
+          AFI->getDPRCalleeSavedAreaOffset()||
+          hasFP(MF)) {
         if (NumBytes)
-          emitThumbRegPlusImmediate(MBB, MBBI, ARM::SP, FramePtr, -NumBytes,
-                                    TII, *this, dl);
+          BuildMI(MBB, MBBI, dl, TII.get(ARM::SUBri), ARM::SP).addReg(FramePtr)
+            .addImm(NumBytes)
+            .addImm((unsigned)ARMCC::AL).addReg(0).addReg(0);
         else
-          BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVlor2hir), ARM::SP)
-            .addReg(FramePtr);
-      } else {
-        if (MBBI->getOpcode() == ARM::tBX_RET &&
-            &MBB.front() != MBBI &&
-            prior(MBBI)->getOpcode() == ARM::tPOP) {
-          MachineBasicBlock::iterator PMBBI = prior(MBBI);
-          emitSPUpdate(MBB, PMBBI, NumBytes, ARMCC::AL, 0, isThumb, TII,
-                       *this, dl);
-        } else
-          emitSPUpdate(MBB, MBBI, NumBytes, ARMCC::AL, 0, isThumb, TII,
-                       *this, dl);
-      }
-    } else {
-      // Darwin ABI requires FP to point to the stack slot that contains the
-      // previous FP.
-      if ((STI.isTargetDarwin() && NumBytes) || hasFP(MF)) {
-        NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
-        // Reset SP based on frame pointer only if the stack frame extends beyond
-        // frame pointer stack slot or target is ELF and the function has FP.
-        if (AFI->getGPRCalleeSavedArea2Size() ||
-            AFI->getDPRCalleeSavedAreaSize()  ||
-            AFI->getDPRCalleeSavedAreaOffset()||
-            hasFP(MF)) {
-          if (NumBytes)
-            BuildMI(MBB, MBBI, dl, TII.get(ARM::SUBri), ARM::SP).addReg(FramePtr)
-              .addImm(NumBytes)
-              .addImm((unsigned)ARMCC::AL).addReg(0).addReg(0);
-          else
-            BuildMI(MBB, MBBI, dl, TII.get(ARM::MOVr), ARM::SP).addReg(FramePtr)
-              .addImm((unsigned)ARMCC::AL).addReg(0).addReg(0);
-        }
-      } else if (NumBytes) {
-        emitSPUpdate(MBB, MBBI, NumBytes, ARMCC::AL, 0, false, TII, *this, dl);
+          BuildMI(MBB, MBBI, dl, TII.get(ARM::MOVr), ARM::SP).addReg(FramePtr)
+            .addImm((unsigned)ARMCC::AL).addReg(0).addReg(0);
       }
+    } else if (NumBytes) {
+      emitSPUpdate(MBB, MBBI, NumBytes, ARMCC::AL, 0, TII, dl);
+    }
 
-      // Move SP to start of integer callee save spill area 2.
-      movePastCSLoadStoreOps(MBB, MBBI, ARM::FLDD, 3, STI);
-      emitSPUpdate(MBB, MBBI, AFI->getDPRCalleeSavedAreaSize(), ARMCC::AL, 0,
-                   false, TII, *this, dl);
+    // Move SP to start of integer callee save spill area 2.
+    movePastCSLoadStoreOps(MBB, MBBI, ARM::FLDD, 3, STI);
+    emitSPUpdate(MBB, MBBI, AFI->getDPRCalleeSavedAreaSize(), ARMCC::AL, 0,
+                 TII, dl);
 
-      // Move SP to start of integer callee save spill area 1.
-      movePastCSLoadStoreOps(MBB, MBBI, ARM::LDR, 2, STI);
-      emitSPUpdate(MBB, MBBI, AFI->getGPRCalleeSavedArea2Size(), ARMCC::AL, 0,
-                   false, TII, *this, dl);
+    // Move SP to start of integer callee save spill area 1.
+    movePastCSLoadStoreOps(MBB, MBBI, ARM::LDR, 2, STI);
+    emitSPUpdate(MBB, MBBI, AFI->getGPRCalleeSavedArea2Size(), ARMCC::AL, 0,
+                 TII, dl);
 
-      // Move SP to SP upon entry to the function.
-      movePastCSLoadStoreOps(MBB, MBBI, ARM::LDR, 1, STI);
-      emitSPUpdate(MBB, MBBI, AFI->getGPRCalleeSavedArea1Size(), ARMCC::AL, 0,
-                   false, TII, *this, dl);
-    }
+    // Move SP to SP upon entry to the function.
+    movePastCSLoadStoreOps(MBB, MBBI, ARM::LDR, 1, STI);
+    emitSPUpdate(MBB, MBBI, AFI->getGPRCalleeSavedArea1Size(), ARMCC::AL, 0,
+                 TII, dl);
   }
 
-  if (VARegSaveSize) {
-    if (isThumb)
-      // Epilogue for vararg functions: pop LR to R3 and branch off it.
-      // FIXME: Verify this is still ok when R3 is no longer being reserved.
-      BuildMI(MBB, MBBI, dl, TII.get(ARM::tPOP)).addReg(ARM::R3);
-
-    emitSPUpdate(MBB, MBBI, VARegSaveSize, ARMCC::AL, 0, isThumb, TII,
-                 *this, dl);
+  if (VARegSaveSize)
+    emitSPUpdate(MBB, MBBI, VARegSaveSize, ARMCC::AL, 0, TII, dl);
 
-    if (isThumb) {
-      BuildMI(MBB, MBBI, dl, TII.get(ARM::tBX_RET_vararg)).addReg(ARM::R3);
-      MBB.erase(MBBI);
-    }
-  }
 }
 
-unsigned ARMRegisterInfo::getRARegister() const {
+unsigned ARMBaseRegisterInfo::getRARegister() const {
   return ARM::LR;
 }
 
-unsigned ARMRegisterInfo::getFrameRegister(MachineFunction &MF) const {
+unsigned ARMBaseRegisterInfo::getFrameRegister(MachineFunction &MF) const {
   if (STI.isTargetDarwin() || hasFP(MF))
     return FramePtr;
   return ARM::SP;
 }
 
-unsigned ARMRegisterInfo::getEHExceptionRegister() const {
+unsigned ARMBaseRegisterInfo::getEHExceptionRegister() const {
   assert(0 && "What is the exception register");
   return 0;
 }
 
-unsigned ARMRegisterInfo::getEHHandlerRegister() const {
+unsigned ARMBaseRegisterInfo::getEHHandlerRegister() const {
   assert(0 && "What is the exception handler register");
   return 0;
 }
 
-int ARMRegisterInfo::getDwarfRegNum(unsigned RegNum, bool isEH) const {
+int ARMBaseRegisterInfo::getDwarfRegNum(unsigned RegNum, bool isEH) const {
   return ARMGenRegisterInfo::getDwarfRegNumFull(RegNum, 0);
 }
 
-unsigned ARMRegisterInfo::getRegisterPairEven(unsigned Reg,
-                                              const MachineFunction &MF) const {
+unsigned ARMBaseRegisterInfo::getRegisterPairEven(unsigned Reg,
+                                               const MachineFunction &MF) const {
   switch (Reg) {
   default: break;
   // Return 0 if either register of the pair is a special register.
@@ -1810,7 +1339,7 @@ unsigned ARMRegisterInfo::getRegisterPairEven(unsigned Reg,
   return 0;
 }
 
-unsigned ARMRegisterInfo::getRegisterPairOdd(unsigned Reg,
+unsigned ARMBaseRegisterInfo::getRegisterPairOdd(unsigned Reg,
                                              const MachineFunction &MF) const {
   switch (Reg) {
   default: break;
diff --git a/lib/Target/ARM/ARMRegisterInfo.h b/lib/Target/ARM/ARMRegisterInfo.h
index e8f4fd805d..1154c0542b 100644
--- a/lib/Target/ARM/ARMRegisterInfo.h
+++ b/lib/Target/ARM/ARMRegisterInfo.h
@@ -14,6 +14,7 @@
 #ifndef ARMREGISTERINFO_H
 #define ARMREGISTERINFO_H
 
+#include "ARM.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "ARMGenRegisterInfo.h.inc"
 
@@ -30,21 +31,15 @@ namespace ARMRI {
   };
 }
 
-struct ARMRegisterInfo : public ARMGenRegisterInfo {
+struct ARMBaseRegisterInfo : public ARMGenRegisterInfo {
+protected:
   const TargetInstrInfo &TII;
   const ARMSubtarget &STI;
 
+  /// FramePtr - ARM physical register used as frame ptr.
+  unsigned FramePtr;
 public:
-  ARMRegisterInfo(const TargetInstrInfo &tii, const ARMSubtarget &STI);
-
-  /// emitLoadConstPool - Emits a load from constpool to materialize the
-  /// specified immediate.
-  void emitLoadConstPool(MachineBasicBlock &MBB,
-                         MachineBasicBlock::iterator &MBBI,
-                         unsigned DestReg, int Val,
-                         unsigned Pred, unsigned PredReg,
-                         const TargetInstrInfo *TII, bool isThumb,
-                         DebugLoc dl) const;
+  ARMBaseRegisterInfo(const TargetInstrInfo &tii, const ARMSubtarget &STI);
 
   /// getRegisterNumbering - Given the enum value for some register, e.g.
   /// ARM::LR, return the number that it corresponds to (e.g. 14).
@@ -55,8 +50,6 @@ public:
   static unsigned getRegisterNumbering(unsigned RegEnum, bool &isSPVFP);
 
   /// Code Generation virtual methods...
-  const TargetRegisterClass *
-    getPhysicalRegisterRegClass(unsigned Reg, MVT VT = MVT::Other) const;
   const unsigned *getCalleeSavedRegs(const MachineFunction *MF = 0) const;
 
   const TargetRegisterClass* const*
@@ -79,25 +72,11 @@ public:
   void UpdateRegAllocHint(unsigned Reg, unsigned NewReg,
                           MachineFunction &MF) const;
 
-  bool requiresRegisterScavenging(const MachineFunction &MF) const;
-
   bool hasFP(const MachineFunction &MF) const;
 
-  bool hasReservedCallFrame(MachineFunction &MF) const;
-
-  void eliminateCallFramePseudoInstr(MachineFunction &MF,
-                                     MachineBasicBlock &MBB,
-                                     MachineBasicBlock::iterator I) const;
-
-  void eliminateFrameIndex(MachineBasicBlock::iterator II,
-                           int SPAdj, RegScavenger *RS = NULL) const;
-
   void processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
                                             RegScavenger *RS = NULL) const;
 
-  void emitPrologue(MachineFunction &MF) const;
-  void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const;
-
   // Debug information queries.
   unsigned getRARegister() const;
   unsigned getFrameRegister(MachineFunction &MF) const;
@@ -107,17 +86,48 @@ public:
   unsigned getEHHandlerRegister() const;
 
   int getDwarfRegNum(unsigned RegNum, bool isEH) const;
-  
+
   bool isLowRegister(unsigned Reg) const;
 
 private:
-  /// FramePtr - ARM physical register used as frame ptr.
-  unsigned FramePtr;
-
   unsigned getRegisterPairEven(unsigned Reg, const MachineFunction &MF) const;
 
   unsigned getRegisterPairOdd(unsigned Reg, const MachineFunction &MF) const;
+};
+
+struct ARMRegisterInfo : public ARMBaseRegisterInfo {
+public:
+  ARMRegisterInfo(const TargetInstrInfo &tii, const ARMSubtarget &STI);
+
+  /// emitLoadConstPool - Emits a load from constpool to materialize the
+  /// specified immediate.
+  void emitLoadConstPool(MachineBasicBlock &MBB,
+                         MachineBasicBlock::iterator &MBBI,
+                         unsigned DestReg, int Val,
+                         unsigned Pred, unsigned PredReg,
+                         const TargetInstrInfo *TII,
+                         DebugLoc dl) const;
+
+  /// Code Generation virtual methods...
+  bool isReservedReg(const MachineFunction &MF, unsigned Reg) const;
+
+  bool requiresRegisterScavenging(const MachineFunction &MF) const;
+
+  bool hasReservedCallFrame(MachineFunction &MF) const;
+
+  void eliminateCallFramePseudoInstr(MachineFunction &MF,
+                                     MachineBasicBlock &MBB,
+                                     MachineBasicBlock::iterator I) const;
+
+  void eliminateFrameIndex(MachineBasicBlock::iterator II,
+                           int SPAdj, RegScavenger *RS = NULL) const;
+
+  void emitPrologue(MachineFunction &MF) const;
+  void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const;
 
+  void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
+                    int NumBytes, ARMCC::CondCodes Pred, unsigned PredReg,
+                    const TargetInstrInfo &TII, DebugLoc dl) const;
 };
 
 } // end namespace llvm
diff --git a/lib/Target/ARM/ARMTargetMachine.h b/lib/Target/ARM/ARMTargetMachine.h
index 0b49b9275b..eab1e46b1d 100644
--- a/lib/Target/ARM/ARMTargetMachine.h
+++ b/lib/Target/ARM/ARMTargetMachine.h
@@ -120,7 +120,7 @@ class ThumbTargetMachine : public ARMBaseTargetMachine {
 public:
   ThumbTargetMachine(const Module &M, const std::string &FS);
 
-  virtual const ARMRegisterInfo  *getRegisterInfo() const {
+  virtual const ThumbRegisterInfo  *getRegisterInfo() const {
     return &InstrInfo.getRegisterInfo();
   }
 
diff --git a/lib/Target/ARM/ThumbInstrInfo.cpp b/lib/Target/ARM/ThumbInstrInfo.cpp
index 075d940bcc..d9a499dacd 100644
--- a/lib/Target/ARM/ThumbInstrInfo.cpp
+++ b/lib/Target/ARM/ThumbInstrInfo.cpp
@@ -23,7 +23,7 @@
 using namespace llvm;
 
 ThumbInstrInfo::ThumbInstrInfo(const ARMSubtarget &STI)
-  : ARMBaseInstrInfo(STI) {
+  : ARMBaseInstrInfo(STI), RI(*this, STI) {
 }
 
 bool ThumbInstrInfo::isMoveInstr(const MachineInstr &MI,
@@ -114,6 +114,37 @@ bool ThumbInstrInfo::copyRegToReg(MachineBasicBlock &MBB,
   return false;
 }
 
+bool ThumbInstrInfo::
+canFoldMemoryOperand(const MachineInstr *MI,
+                     const SmallVectorImpl<unsigned> &Ops) const {
+  if (Ops.size() != 1) return false;
+
+  unsigned OpNum = Ops[0];
+  unsigned Opc = MI->getOpcode();
+  switch (Opc) {
+  default: break;
+  case ARM::tMOVr:
+  case ARM::tMOVlor2hir:
+  case ARM::tMOVhir2lor:
+  case ARM::tMOVhir2hir: {
+    if (OpNum == 0) { // move -> store
+      unsigned SrcReg = MI->getOperand(1).getReg();
+      if (RI.isPhysicalRegister(SrcReg) && !RI.isLowRegister(SrcReg))
+        // tSpill cannot take a high register operand.
+        return false;
+    } else {          // move -> load
+      unsigned DstReg = MI->getOperand(0).getReg();
+      if (RI.isPhysicalRegister(DstReg) && !RI.isLowRegister(DstReg))
+        // tRestore cannot target a high register operand.
+        return false;
+    }
+    return true;
+  }
+  }
+
+  return false;
+}
+
 void ThumbInstrInfo::
 storeRegToStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
                     unsigned SrcReg, bool isKill, int FI,
@@ -244,7 +275,6 @@ MachineInstr *ThumbInstrInfo::
 foldMemoryOperandImpl(MachineFunction &MF, MachineInstr *MI,
                       const SmallVectorImpl<unsigned> &Ops, int FI) const {
   if (Ops.size() != 1) return NULL;
-  const ARMRegisterInfo &RI = getRegisterInfo();
 
   unsigned OpNum = Ops[0];
   unsigned Opc = MI->getOpcode();
diff --git a/lib/Target/ARM/ThumbInstrInfo.h b/lib/Target/ARM/ThumbInstrInfo.h
index dcf1095750..eefd07780d 100644
--- a/lib/Target/ARM/ThumbInstrInfo.h
+++ b/lib/Target/ARM/ThumbInstrInfo.h
@@ -15,17 +15,24 @@
 #define THUMBINSTRUCTIONINFO_H
 
 #include "llvm/Target/TargetInstrInfo.h"
-#include "ARMRegisterInfo.h"
 #include "ARM.h"
 #include "ARMInstrInfo.h"
+#include "ThumbRegisterInfo.h"
 
 namespace llvm {
   class ARMSubtarget;
 
 class ThumbInstrInfo : public ARMBaseInstrInfo {
+  ThumbRegisterInfo RI;
 public:
   explicit ThumbInstrInfo(const ARMSubtarget &STI);
 
+  /// getRegisterInfo - TargetInstrInfo is a superset of MRegister info.  As
+  /// such, whenever a client has an instance of instruction info, it should
+  /// always be able to get register info as well (through this method).
+  ///
+  virtual const ThumbRegisterInfo &getRegisterInfo() const { return RI; }
+
   /// Return true if the instruction is a register to register move and return
   /// the source and dest operands and their sub-register indices by reference.
   virtual bool isMoveInstr(const MachineInstr &MI,
@@ -68,6 +75,9 @@ public:
                                            MachineBasicBlock::iterator MI,
                                  const std::vector<CalleeSavedInfo> &CSI) const;
 
+  virtual bool canFoldMemoryOperand(const MachineInstr *MI,
+                                    const SmallVectorImpl<unsigned> &Ops) const;
+
   virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
                                               MachineInstr* MI,
                                            const SmallVectorImpl<unsigned> &Ops,
diff --git a/lib/Target/ARM/ThumbRegisterInfo.cpp b/lib/Target/ARM/ThumbRegisterInfo.cpp
new file mode 100644
index 0000000000..40221d9cf7
--- /dev/null
+++ b/lib/Target/ARM/ThumbRegisterInfo.cpp
@@ -0,0 +1,757 @@
+//===- ThumbRegisterInfo.cpp - Thumb Register Information -------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the ARM implementation of the TargetRegisterInfo class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ARM.h"
+#include "ARMAddressingModes.h"
+#include "ARMMachineFunctionInfo.h"
+#include "ARMSubtarget.h"
+#include "ThumbInstrInfo.h"
+#include "ThumbRegisterInfo.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/CodeGen/MachineConstantPool.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineLocation.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Target/TargetFrameInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/CommandLine.h"
+using namespace llvm;
+
+static cl::opt<bool>
+ThumbRegScavenging("enable-thumb-reg-scavenging",
+                   cl::Hidden,
+                   cl::desc("Enable register scavenging on Thumb"));
+
+ThumbRegisterInfo::ThumbRegisterInfo(const TargetInstrInfo &tii,
+                                     const ARMSubtarget &sti)
+  : ARMBaseRegisterInfo(tii, sti) {
+}
+
+/// emitLoadConstPool - Emits a load from constpool to materialize the
+/// specified immediate.
+void ThumbRegisterInfo::emitLoadConstPool(MachineBasicBlock &MBB,
+                                          MachineBasicBlock::iterator &MBBI,
+                                          unsigned DestReg, int Val,
+                                          unsigned Pred, unsigned PredReg,
+                                          const TargetInstrInfo *TII,
+                                          DebugLoc dl) const {
+  MachineFunction &MF = *MBB.getParent();
+  MachineConstantPool *ConstantPool = MF.getConstantPool();
+  Constant *C = ConstantInt::get(Type::Int32Ty, Val);
+  unsigned Idx = ConstantPool->getConstantPoolIndex(C, 4);
+
+  BuildMI(MBB, MBBI, dl, TII->get(ARM::tLDRcp), DestReg)
+    .addConstantPoolIndex(Idx);
+}
+
+const TargetRegisterClass*
+ThumbRegisterInfo::getPhysicalRegisterRegClass(unsigned Reg, MVT VT) const {
+  if (isLowRegister(Reg))
+    return ARM::tGPRRegisterClass;
+  switch (Reg) {
+   default:
+    break;
+   case ARM::R8:  case ARM::R9:  case ARM::R10:  case ARM::R11:
+   case ARM::R12: case ARM::SP:  case ARM::LR:   case ARM::PC:
+    return ARM::GPRRegisterClass;
+  }
+
+  return TargetRegisterInfo::getPhysicalRegisterRegClass(Reg, VT);
+}
+
+bool
+ThumbRegisterInfo::requiresRegisterScavenging(const MachineFunction &MF) const {
+  return ThumbRegScavenging;
+}
+
+bool ThumbRegisterInfo::hasReservedCallFrame(MachineFunction &MF) const {
+  const MachineFrameInfo *FFI = MF.getFrameInfo();
+  unsigned CFSize = FFI->getMaxCallFrameSize();
+  // It's not always a good idea to include the call frame as part of the
+  // stack frame. ARM (especially Thumb) has small immediate offset to
+  // address the stack frame. So a large call frame can cause poor codegen
+  // and may even makes it impossible to scavenge a register.
+  if (CFSize >= ((1 << 8) - 1) * 4 / 2) // Half of imm8 * 4
+    return false;
+
+  return !MF.getFrameInfo()->hasVarSizedObjects();
+}
+
+/// emitThumbRegPlusImmInReg - Emits a series of instructions to materialize
+/// a destreg = basereg + immediate in Thumb code. Materialize the immediate
+/// in a register using mov / mvn sequences or load the immediate from a
+/// constpool entry.
+static
+void emitThumbRegPlusImmInReg(MachineBasicBlock &MBB,
+                              MachineBasicBlock::iterator &MBBI,
+                              unsigned DestReg, unsigned BaseReg,
+                              int NumBytes, bool CanChangeCC,
+                              const TargetInstrInfo &TII,
+                              const ThumbRegisterInfo& MRI,
+                              DebugLoc dl) {
+    bool isHigh = !MRI.isLowRegister(DestReg) ||
+                  (BaseReg != 0 && !MRI.isLowRegister(BaseReg));
+    bool isSub = false;
+    // Subtract doesn't have high register version. Load the negative value
+    // if either base or dest register is a high register. Also, if do not
+    // issue sub as part of the sequence if condition register is to be
+    // preserved.
+    if (NumBytes < 0 && !isHigh && CanChangeCC) {
+      isSub = true;
+      NumBytes = -NumBytes;
+    }
+    unsigned LdReg = DestReg;
+    if (DestReg == ARM::SP) {
+      assert(BaseReg == ARM::SP && "Unexpected!");
+      LdReg = ARM::R3;
+      BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVlor2hir), ARM::R12)
+        .addReg(ARM::R3, RegState::Kill);
+    }
+
+    if (NumBytes <= 255 && NumBytes >= 0)
+      BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVi8), LdReg).addImm(NumBytes);
+    else if (NumBytes < 0 && NumBytes >= -255) {
+      BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVi8), LdReg).addImm(NumBytes);
+      BuildMI(MBB, MBBI, dl, TII.get(ARM::tNEG), LdReg)
+        .addReg(LdReg, RegState::Kill);
+    } else
+      MRI.emitLoadConstPool(MBB, MBBI, LdReg, NumBytes, ARMCC::AL, 0, &TII, dl);
+
+    // Emit add / sub.
+    int Opc = (isSub) ? ARM::tSUBrr : (isHigh ? ARM::tADDhirr : ARM::tADDrr);
+    const MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl,
+                                            TII.get(Opc), DestReg);
+    if (DestReg == ARM::SP || isSub)
+      MIB.addReg(BaseReg).addReg(LdReg, RegState::Kill);
+    else
+      MIB.addReg(LdReg).addReg(BaseReg, RegState::Kill);
+    if (DestReg == ARM::SP)
+      BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVhir2lor), ARM::R3)
+        .addReg(ARM::R12, RegState::Kill);
+}
+
+/// calcNumMI - Returns the number of instructions required to materialize
+/// the specific add / sub r, c instruction.
+static unsigned calcNumMI(int Opc, int ExtraOpc, unsigned Bytes,
+                          unsigned NumBits, unsigned Scale) {
+  unsigned NumMIs = 0;
+  unsigned Chunk = ((1 << NumBits) - 1) * Scale;
+
+  if (Opc == ARM::tADDrSPi) {
+    unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
+    Bytes -= ThisVal;
+    NumMIs++;
+    NumBits = 8;
+    Scale = 1;  // Followed by a number of tADDi8.
+    Chunk = ((1 << NumBits) - 1) * Scale;
+  }
+
+  NumMIs += Bytes / Chunk;
+  if ((Bytes % Chunk) != 0)
+    NumMIs++;
+  if (ExtraOpc)
+    NumMIs++;
+  return NumMIs;
+}
+
+/// emitThumbRegPlusImmediate - Emits a series of instructions to materialize
+/// a destreg = basereg + immediate in Thumb code.
+static
+void emitThumbRegPlusImmediate(MachineBasicBlock &MBB,
+                               MachineBasicBlock::iterator &MBBI,
+                               unsigned DestReg, unsigned BaseReg,
+                               int NumBytes, const TargetInstrInfo &TII,
+                               const ThumbRegisterInfo& MRI,
+                               DebugLoc dl) {
+  bool isSub = NumBytes < 0;
+  unsigned Bytes = (unsigned)NumBytes;
+  if (isSub) Bytes = -NumBytes;
+  bool isMul4 = (Bytes & 3) == 0;
+  bool isTwoAddr = false;
+  bool DstNotEqBase = false;
+  unsigned NumBits = 1;
+  unsigned Scale = 1;
+  int Opc = 0;
+  int ExtraOpc = 0;
+
+  if (DestReg == BaseReg && BaseReg == ARM::SP) {
+    assert(isMul4 && "Thumb sp inc / dec size must be multiple of 4!");
+    NumBits = 7;
+    Scale = 4;
+    Opc = isSub ? ARM::tSUBspi : ARM::tADDspi;
+    isTwoAddr = true;
+  } else if (!isSub && BaseReg == ARM::SP) {
+    // r1 = add sp, 403
+    // =>
+    // r1 = add sp, 100 * 4
+    // r1 = add r1, 3
+    if (!isMul4) {
+      Bytes &= ~3;
+      ExtraOpc = ARM::tADDi3;
+    }
+    NumBits = 8;
+    Scale = 4;
+    Opc = ARM::tADDrSPi;
+  } else {
+    // sp = sub sp, c
+    // r1 = sub sp, c
+    // r8 = sub sp, c
+    if (DestReg != BaseReg)
+      DstNotEqBase = true;
+    NumBits = 8;
+    Opc = isSub ? ARM::tSUBi8 : ARM::tADDi8;
+    isTwoAddr = true;
+  }
+
+  unsigned NumMIs = calcNumMI(Opc, ExtraOpc, Bytes, NumBits, Scale);
+  unsigned Threshold = (DestReg == ARM::SP) ? 3 : 2;
+  if (NumMIs > Threshold) {
+    // This will expand into too many instructions. Load the immediate from a
+    // constpool entry.
+    emitThumbRegPlusImmInReg(MBB, MBBI, DestReg, BaseReg, NumBytes, true, TII,
+                             MRI, dl);
+    return;
+  }
+
+  if (DstNotEqBase) {
+    if (MRI.isLowRegister(DestReg) && MRI.isLowRegister(BaseReg)) {
+      // If both are low registers, emit DestReg = add BaseReg, max(Imm, 7)
+      unsigned Chunk = (1 << 3) - 1;
+      unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
+      Bytes -= ThisVal;
+      BuildMI(MBB, MBBI, dl,TII.get(isSub ? ARM::tSUBi3 : ARM::tADDi3), DestReg)
+        .addReg(BaseReg, RegState::Kill).addImm(ThisVal);
+    } else {
+      BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), DestReg)
+        .addReg(BaseReg, RegState::Kill);
+    }
+    BaseReg = DestReg;
+  }
+
+  unsigned Chunk = ((1 << NumBits) - 1) * Scale;
+  while (Bytes) {
+    unsigned ThisVal = (Bytes > Chunk) ? Chunk : Bytes;
+    Bytes -= ThisVal;
+    ThisVal /= Scale;
+    // Build the new tADD / tSUB.
+    if (isTwoAddr)
+      BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
+        .addReg(DestReg).addImm(ThisVal);
+    else {
+      bool isKill = BaseReg != ARM::SP;
+      BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
+        .addReg(BaseReg, getKillRegState(isKill)).addImm(ThisVal);
+      BaseReg = DestReg;
+
+      if (Opc == ARM::tADDrSPi) {
+        // r4 = add sp, imm
+        // r4 = add r4, imm
+        // ...
+        NumBits = 8;
+        Scale = 1;
+        Chunk = ((1 << NumBits) - 1) * Scale;
+        Opc = isSub ? ARM::tSUBi8 : ARM::tADDi8;
+        isTwoAddr = true;
+      }
+    }
+  }
+
+  if (ExtraOpc)
+    BuildMI(MBB, MBBI, dl, TII.get(ExtraOpc), DestReg)
+      .addReg(DestReg, RegState::Kill)
+      .addImm(((unsigned)NumBytes) & 3);
+}
+
+void ThumbRegisterInfo::
+emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
+             int NumBytes, ARMCC::CondCodes Pred, unsigned PredReg,
+             const TargetInstrInfo &TII, DebugLoc dl) const {
+  emitThumbRegPlusImmediate(MBB, MBBI, ARM::SP, ARM::SP, NumBytes, TII,
+                            *this, dl);
+}
+
+void ThumbRegisterInfo::
+eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
+                              MachineBasicBlock::iterator I) const {
+  if (!hasReservedCallFrame(MF)) {
+    // If we have alloca, convert as follows:
+    // ADJCALLSTACKDOWN -> sub, sp, sp, amount
+    // ADJCALLSTACKUP   -> add, sp, sp, amount
+    MachineInstr *Old = I;
+    DebugLoc dl = Old->getDebugLoc();
+    unsigned Amount = Old->getOperand(0).getImm();
+    if (Amount != 0) {
+      // We need to keep the stack aligned properly.  To do this, we round the
+      // amount of space needed for the outgoing arguments up to the next
+      // alignment boundary.
+      unsigned Align = MF.getTarget().getFrameInfo()->getStackAlignment();
+      Amount = (Amount+Align-1)/Align*Align;
+
+      // Replace the pseudo instruction with a new instruction...
+      unsigned Opc = Old->getOpcode();
+      if (Opc == ARM::ADJCALLSTACKDOWN || Opc == ARM::tADJCALLSTACKDOWN) {
+        // Note: PredReg is operand 2 for ADJCALLSTACKDOWN.
+        emitSPUpdate(MBB, I, -Amount, ARMCC::AL, 0, TII, dl);
+      } else {
+        // Note: PredReg is operand 3 for ADJCALLSTACKUP.
+        assert(Opc == ARM::ADJCALLSTACKUP || Opc == ARM::tADJCALLSTACKUP);
+        emitSPUpdate(MBB, I, Amount, ARMCC::AL, 0, TII, dl);
+      }
+    }
+  }
+  MBB.erase(I);
+}
+
+/// emitThumbConstant - Emit a series of instructions to materialize a
+/// constant.
+static void emitThumbConstant(MachineBasicBlock &MBB,
+                              MachineBasicBlock::iterator &MBBI,
+                              unsigned DestReg, int Imm,
+                              const TargetInstrInfo &TII,
+                              const ThumbRegisterInfo& MRI,
+                              DebugLoc dl) {
+  bool isSub = Imm < 0;
+  if (isSub) Imm = -Imm;
+
+  int Chunk = (1 << 8) - 1;
+  int ThisVal = (Imm > Chunk) ? Chunk : Imm;
+  Imm -= ThisVal;
+  BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVi8), DestReg).addImm(ThisVal);
+  if (Imm > 0)
+    emitThumbRegPlusImmediate(MBB, MBBI, DestReg, DestReg, Imm, TII, MRI, dl);
+  if (isSub)
+    BuildMI(MBB, MBBI, dl, TII.get(ARM::tNEG), DestReg)
+      .addReg(DestReg, RegState::Kill);
+}
+
+void ThumbRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
+                                            int SPAdj, RegScavenger *RS) const{
+  unsigned i = 0;
+  MachineInstr &MI = *II;
+  MachineBasicBlock &MBB = *MI.getParent();
+  MachineFunction &MF = *MBB.getParent();
+  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
+  DebugLoc dl = MI.getDebugLoc();
+
+  while (!MI.getOperand(i).isFI()) {
+    ++i;
+    assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
+  }
+
+  unsigned FrameReg = ARM::SP;
+  int FrameIndex = MI.getOperand(i).getIndex();
+  int Offset = MF.getFrameInfo()->getObjectOffset(FrameIndex) +
+               MF.getFrameInfo()->getStackSize() + SPAdj;
+
+  if (AFI->isGPRCalleeSavedArea1Frame(FrameIndex))
+    Offset -= AFI->getGPRCalleeSavedArea1Offset();
+  else if (AFI->isGPRCalleeSavedArea2Frame(FrameIndex))
+    Offset -= AFI->getGPRCalleeSavedArea2Offset();
+  else if (hasFP(MF)) {
+    assert(SPAdj == 0 && "Unexpected");
+    // There is alloca()'s in this function, must reference off the frame
+    // pointer instead.
+    FrameReg = getFrameRegister(MF);
+    Offset -= AFI->getFramePtrSpillOffset();
+  }
+
+  unsigned Opcode = MI.getOpcode();
+  const TargetInstrDesc &Desc = MI.getDesc();
+  unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
+
+  if (Opcode == ARM::tADDrSPi) {
+    Offset += MI.getOperand(i+1).getImm();
+
+    // Can't use tADDrSPi if it's based off the frame pointer.
+    unsigned NumBits = 0;
+    unsigned Scale = 1;
+    if (FrameReg != ARM::SP) {
+      Opcode = ARM::tADDi3;
+      MI.setDesc(TII.get(ARM::tADDi3));
+      NumBits = 3;
+    } else {
+      NumBits = 8;
+      Scale = 4;
+      assert((Offset & 3) == 0 &&
+             "Thumb add/sub sp, #imm immediate must be multiple of 4!");
+    }
+
+    if (Offset == 0) {
+      // Turn it into a move.
+      MI.setDesc(TII.get(ARM::tMOVhir2lor));
+      MI.getOperand(i).ChangeToRegister(FrameReg, false);
+      MI.RemoveOperand(i+1);
+      return;
+    }
+
+    // Common case: small offset, fits into instruction.
+    unsigned Mask = (1 << NumBits) - 1;
+    if (((Offset / Scale) & ~Mask) == 0) {
+      // Replace the FrameIndex with sp / fp
+      MI.getOperand(i).ChangeToRegister(FrameReg, false);
+      MI.getOperand(i+1).ChangeToImmediate(Offset / Scale);
+      return;
+    }
+
+    unsigned DestReg = MI.getOperand(0).getReg();
+    unsigned Bytes = (Offset > 0) ? Offset : -Offset;
+    unsigned NumMIs = calcNumMI(Opcode, 0, Bytes, NumBits, Scale);
+    // MI would expand into a large number of instructions. Don't try to
+    // simplify the immediate.
+    if (NumMIs > 2) {
+      emitThumbRegPlusImmediate(MBB, II, DestReg, FrameReg, Offset, TII,
+                                *this, dl);
+      MBB.erase(II);
+      return;
+    }
+
+    if (Offset > 0) {
+      // Translate r0 = add sp, imm to
+      // r0 = add sp, 255*4
+      // r0 = add r0, (imm - 255*4)
+      MI.getOperand(i).ChangeToRegister(FrameReg, false);
+      MI.getOperand(i+1).ChangeToImmediate(Mask);
+      Offset = (Offset - Mask * Scale);
+      MachineBasicBlock::iterator NII = next(II);
+      emitThumbRegPlusImmediate(MBB, NII, DestReg, DestReg, Offset, TII,
+                                *this, dl);
+    } else {
+      // Translate r0 = add sp, -imm to
+      // r0 = -imm (this is then translated into a series of instructons)
+      // r0 = add r0, sp
+      emitThumbConstant(MBB, II, DestReg, Offset, TII, *this, dl);
+      MI.setDesc(TII.get(ARM::tADDhirr));
+      MI.getOperand(i).ChangeToRegister(DestReg, false, false, true);
+      MI.getOperand(i+1).ChangeToRegister(FrameReg, false);
+    }
+    return;
+  } else {
+    unsigned ImmIdx = 0;
+    int InstrOffs = 0;
+    unsigned NumBits = 0;
+    unsigned Scale = 1;
+    switch (AddrMode) {
+    case ARMII::AddrModeTs: {
+      ImmIdx = i+1;
+      InstrOffs = MI.getOperand(ImmIdx).getImm();
+      NumBits = (FrameReg == ARM::SP) ? 8 : 5;
+      Scale = 4;
+      break;
+    }
+    default:
+      assert(0 && "Unsupported addressing mode!");
+      abort();
+      break;
+    }
+
+    Offset += InstrOffs * Scale;
+    assert((Offset & (Scale-1)) == 0 && "Can't encode this offset!");
+
+    // Common case: small offset, fits into instruction.
+    MachineOperand &ImmOp = MI.getOperand(ImmIdx);
+    int ImmedOffset = Offset / Scale;
+    unsigned Mask = (1 << NumBits) - 1;
+    if ((unsigned)Offset <= Mask * Scale) {
+      // Replace the FrameIndex with sp
+      MI.getOperand(i).ChangeToRegister(FrameReg, false);
+      ImmOp.ChangeToImmediate(ImmedOffset);
+      return;
+    }
+
+    bool isThumSpillRestore = Opcode == ARM::tRestore || Opcode == ARM::tSpill;
+    if (AddrMode == ARMII::AddrModeTs) {
+      // Thumb tLDRspi, tSTRspi. These will change to instructions that use
+      // a different base register.
+      NumBits = 5;
+      Mask = (1 << NumBits) - 1;
+    }
+    // If this is a thumb spill / restore, we will be using a constpool load to
+    // materialize the offset.
+    if (AddrMode == ARMII::AddrModeTs && isThumSpillRestore)
+      ImmOp.ChangeToImmediate(0);
+    else {
+      // Otherwise, it didn't fit. Pull in what we can to simplify the immed.
+      ImmedOffset = ImmedOffset & Mask;
+      ImmOp.ChangeToImmediate(ImmedOffset);
+      Offset &= ~(Mask*Scale);
+    }
+  }
+
+  // If we get here, the immediate doesn't fit into the instruction.  We folded
+  // as much as possible above, handle the rest, providing a register that is
+  // SP+LargeImm.
+  assert(Offset && "This code isn't needed if offset already handled!");
+
+  if (Desc.mayLoad()) {
+    // Use the destination register to materialize sp + offset.
+    unsigned TmpReg = MI.getOperand(0).getReg();
+    bool UseRR = false;
+    if (Opcode == ARM::tRestore) {
+      if (FrameReg == ARM::SP)
+        emitThumbRegPlusImmInReg(MBB, II, TmpReg, FrameReg,
+                                 Offset, false, TII, *this, dl);
+      else {
+        emitLoadConstPool(MBB, II, TmpReg, Offset, ARMCC::AL, 0, &TII, dl);
+        UseRR = true;
+      }
+    } else
+      emitThumbRegPlusImmediate(MBB, II, TmpReg, FrameReg, Offset, TII,
+                                *this, dl);
+    MI.setDesc(TII.get(ARM::tLDR));
+    MI.getOperand(i).ChangeToRegister(TmpReg, false, false, true);
+    if (UseRR)
+      // Use [reg, reg] addrmode.
+      MI.addOperand(MachineOperand::CreateReg(FrameReg, false));
+    else  // tLDR has an extra register operand.
+      MI.addOperand(MachineOperand::CreateReg(0, false));
+  } else if (Desc.mayStore()) {
+    // FIXME! This is horrific!!! We need register scavenging.
+    // Our temporary workaround has marked r3 unavailable. Of course, r3 is
+    // also a ABI register so it's possible that is is the register that is
+    // being storing here. If that's the case, we do the following:
+    // r12 = r2
+    // Use r2 to materialize sp + offset
+    // str r3, r2
+    // r2 = r12
+    unsigned ValReg = MI.getOperand(0).getReg();
+    unsigned TmpReg = ARM::R3;
+    bool UseRR = false;
+    if (ValReg == ARM::R3) {
+      BuildMI(MBB, II, dl, TII.get(ARM::tMOVlor2hir), ARM::R12)
+        .addReg(ARM::R2, RegState::Kill);
+      TmpReg = ARM::R2;
+    }
+    if (TmpReg == ARM::R3 && AFI->isR3LiveIn())
+      BuildMI(MBB, II, dl, TII.get(ARM::tMOVlor2hir), ARM::R12)
+        .addReg(ARM::R3, RegState::Kill);
+    if (Opcode == ARM::tSpill) {
+      if (FrameReg == ARM::SP)
+        emitThumbRegPlusImmInReg(MBB, II, TmpReg, FrameReg,
+                                 Offset, false, TII, *this, dl);
+      else {
+        emitLoadConstPool(MBB, II, TmpReg, Offset, ARMCC::AL, 0, &TII, dl);
+        UseRR = true;
+      }
+    } else
+      emitThumbRegPlusImmediate(MBB, II, TmpReg, FrameReg, Offset, TII,
+                                *this, dl);
+    MI.setDesc(TII.get(ARM::tSTR));
+    MI.getOperand(i).ChangeToRegister(TmpReg, false, false, true);
+    if (UseRR)  // Use [reg, reg] addrmode.
+      MI.addOperand(MachineOperand::CreateReg(FrameReg, false));
+    else // tSTR has an extra register operand.
+      MI.addOperand(MachineOperand::CreateReg(0, false));
+
+    MachineBasicBlock::iterator NII = next(II);
+    if (ValReg == ARM::R3)
+      BuildMI(MBB, NII, dl, TII.get(ARM::tMOVhir2lor), ARM::R2)
+        .addReg(ARM::R12, RegState::Kill);
+    if (TmpReg == ARM::R3 && AFI->isR3LiveIn())
+      BuildMI(MBB, NII, dl, TII.get(ARM::tMOVhir2lor), ARM::R3)
+        .addReg(ARM::R12, RegState::Kill);
+  } else
+    assert(false && "Unexpected opcode!");
+}
+
+void ThumbRegisterInfo::emitPrologue(MachineFunction &MF) const {
+  MachineBasicBlock &MBB = MF.front();
+  MachineBasicBlock::iterator MBBI = MBB.begin();
+  MachineFrameInfo  *MFI = MF.getFrameInfo();
+  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
+  unsigned VARegSaveSize = AFI->getVarArgsRegSaveSize();
+  unsigned NumBytes = MFI->getStackSize();
+  const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
+  DebugLoc dl = (MBBI != MBB.end() ?
+                 MBBI->getDebugLoc() : DebugLoc::getUnknownLoc());
+
+  // Check if R3 is live in. It might have to be used as a scratch register.
+  for (MachineRegisterInfo::livein_iterator I =MF.getRegInfo().livein_begin(),
+         E = MF.getRegInfo().livein_end(); I != E; ++I) {
+    if (I->first == ARM::R3) {
+      AFI->setR3IsLiveIn(true);
+      break;
+    }
+  }
+
+  // Thumb add/sub sp, imm8 instructions implicitly multiply the offset by 4.
+  NumBytes = (NumBytes + 3) & ~3;
+  MFI->setStackSize(NumBytes);
+
+  // Determine the sizes of each callee-save spill areas and record which frame
+  // belongs to which callee-save spill areas.
+  unsigned GPRCS1Size = 0, GPRCS2Size = 0, DPRCSSize = 0;
+  int FramePtrSpillFI = 0;
+
+  if (VARegSaveSize)
+    emitSPUpdate(MBB, MBBI, -VARegSaveSize, ARMCC::AL, 0, TII, dl);
+
+  if (!AFI->hasStackFrame()) {
+    if (NumBytes != 0)
+      emitSPUpdate(MBB, MBBI, -NumBytes, ARMCC::AL, 0, TII, dl);
+    return;
+  }
+
+  for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+    unsigned Reg = CSI[i].getReg();
+    int FI = CSI[i].getFrameIdx();
+    switch (Reg) {
+    case ARM::R4:
+    case ARM::R5:
+    case ARM::R6:
+    case ARM::R7:
+    case ARM::LR:
+      if (Reg == FramePtr)
+        FramePtrSpillFI = FI;
+      AFI->addGPRCalleeSavedArea1Frame(FI);
+      GPRCS1Size += 4;
+      break;
+    case ARM::R8:
+    case ARM::R9:
+    case ARM::R10:
+    case ARM::R11:
+      if (Reg == FramePtr)
+        FramePtrSpillFI = FI;
+      if (STI.isTargetDarwin()) {
+        AFI->addGPRCalleeSavedArea2Frame(FI);
+        GPRCS2Size += 4;
+      } else {
+        AFI->addGPRCalleeSavedArea1Frame(FI);
+        GPRCS1Size += 4;
+      }
+      break;
+    default:
+      AFI->addDPRCalleeSavedAreaFrame(FI);
+      DPRCSSize += 8;
+    }
+  }
+
+  if (MBBI != MBB.end() && MBBI->getOpcode() == ARM::tPUSH) {
+    ++MBBI;
+    if (MBBI != MBB.end())
+      dl = MBBI->getDebugLoc();
+  }
+
+  // Darwin ABI requires FP to point to the stack slot that contains the
+  // previous FP.
+  if (STI.isTargetDarwin() || hasFP(MF)) {
+    MachineInstrBuilder MIB =
+      BuildMI(MBB, MBBI, dl, TII.get(ARM::tADDrSPi), FramePtr)
+      .addFrameIndex(FramePtrSpillFI).addImm(0);
+  }
+
+  // Determine starting offsets of spill areas.
+  unsigned DPRCSOffset  = NumBytes - (GPRCS1Size + GPRCS2Size + DPRCSSize);
+  unsigned GPRCS2Offset = DPRCSOffset + DPRCSSize;
+  unsigned GPRCS1Offset = GPRCS2Offset + GPRCS2Size;
+  AFI->setFramePtrSpillOffset(MFI->getObjectOffset(FramePtrSpillFI) + NumBytes);
+  AFI->setGPRCalleeSavedArea1Offset(GPRCS1Offset);
+  AFI->setGPRCalleeSavedArea2Offset(GPRCS2Offset);
+  AFI->setDPRCalleeSavedAreaOffset(DPRCSOffset);
+
+  NumBytes = DPRCSOffset;
+  if (NumBytes) {
+    // Insert it after all the callee-save spills.
+    emitSPUpdate(MBB, MBBI, -NumBytes, ARMCC::AL, 0, TII, dl);
+  }
+
+  if (STI.isTargetELF() && hasFP(MF)) {
+    MFI->setOffsetAdjustment(MFI->getOffsetAdjustment() -
+                             AFI->getFramePtrSpillOffset());
+  }
+
+  AFI->setGPRCalleeSavedArea1Size(GPRCS1Size);
+  AFI->setGPRCalleeSavedArea2Size(GPRCS2Size);
+  AFI->setDPRCalleeSavedAreaSize(DPRCSSize);
+}
+
+static bool isCalleeSavedRegister(unsigned Reg, const unsigned *CSRegs) {
+  for (unsigned i = 0; CSRegs[i]; ++i)
+    if (Reg == CSRegs[i])
+      return true;
+  return false;
+}
+
+static bool isCSRestore(MachineInstr *MI, const unsigned *CSRegs) {
+  return (MI->getOpcode() == ARM::tRestore &&
+          MI->getOperand(1).isFI() &&
+          isCalleeSavedRegister(MI->getOperand(0).getReg(), CSRegs));
+}
+
+void ThumbRegisterInfo::emitEpilogue(MachineFunction &MF,
+                                   MachineBasicBlock &MBB) const {
+  MachineBasicBlock::iterator MBBI = prior(MBB.end());
+  assert((MBBI->getOpcode() == ARM::tBX_RET ||
+          MBBI->getOpcode() == ARM::tPOP_RET) &&
+         "Can only insert epilog into returning blocks");
+  DebugLoc dl = MBBI->getDebugLoc();
+  MachineFrameInfo *MFI = MF.getFrameInfo();
+  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
+  unsigned VARegSaveSize = AFI->getVarArgsRegSaveSize();
+  int NumBytes = (int)MFI->getStackSize();
+
+  if (!AFI->hasStackFrame()) {
+    if (NumBytes != 0)
+      emitSPUpdate(MBB, MBBI, NumBytes, ARMCC::AL, 0, TII, dl);
+  } else {
+    // Unwind MBBI to point to first LDR / FLDD.
+    const unsigned *CSRegs = getCalleeSavedRegs();
+    if (MBBI != MBB.begin()) {
+      do
+        --MBBI;
+      while (MBBI != MBB.begin() && isCSRestore(MBBI, CSRegs));
+      if (!isCSRestore(MBBI, CSRegs))
+        ++MBBI;
+    }
+
+    // Move SP to start of FP callee save spill area.
+    NumBytes -= (AFI->getGPRCalleeSavedArea1Size() +
+                 AFI->getGPRCalleeSavedArea2Size() +
+                 AFI->getDPRCalleeSavedAreaSize());
+
+    if (hasFP(MF)) {
+      NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
+      // Reset SP based on frame pointer only if the stack frame extends beyond
+      // frame pointer stack slot or target is ELF and the function has FP.
+      if (NumBytes)
+        emitThumbRegPlusImmediate(MBB, MBBI, ARM::SP, FramePtr, -NumBytes,
+                                  TII, *this, dl);
+      else
+        BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVlor2hir), ARM::SP)
+          .addReg(FramePtr);
+    } else {
+      if (MBBI->getOpcode() == ARM::tBX_RET &&
+          &MBB.front() != MBBI &&
+          prior(MBBI)->getOpcode() == ARM::tPOP) {
+        MachineBasicBlock::iterator PMBBI = prior(MBBI);
+        emitSPUpdate(MBB, PMBBI, NumBytes, ARMCC::AL, 0, TII, dl);
+      } else
+        emitSPUpdate(MBB, MBBI, NumBytes, ARMCC::AL, 0, TII, dl);
+    }
+  }
+
+  if (VARegSaveSize) {
+    // Epilogue for vararg functions: pop LR to R3 and branch off it.
+    // FIXME: Verify this is still ok when R3 is no longer being reserved.
+    BuildMI(MBB, MBBI, dl, TII.get(ARM::tPOP)).addReg(ARM::R3);
+
+    emitSPUpdate(MBB, MBBI, VARegSaveSize, ARMCC::AL, 0, TII, dl);
+
+    BuildMI(MBB, MBBI, dl, TII.get(ARM::tBX_RET_vararg)).addReg(ARM::R3);
+    MBB.erase(MBBI);
+  }
+}
diff --git a/lib/Target/ARM/ThumbRegisterInfo.h b/lib/Target/ARM/ThumbRegisterInfo.h
new file mode 100644
index 0000000000..b1adc31858
--- /dev/null
+++ b/lib/Target/ARM/ThumbRegisterInfo.h
@@ -0,0 +1,65 @@
+//===- ThumbRegisterInfo.h - Thumb Register Information Impl ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the ARM implementation of the TargetRegisterInfo class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef THUMBREGISTERINFO_H
+#define THUMBREGISTERINFO_H
+
+#include "ARM.h"
+#include "ARMRegisterInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+
+namespace llvm {
+  class ARMSubtarget;
+  class TargetInstrInfo;
+  class Type;
+
+struct ThumbRegisterInfo : public ARMBaseRegisterInfo {
+public:
+  ThumbRegisterInfo(const TargetInstrInfo &tii, const ARMSubtarget &STI);
+
+  /// emitLoadConstPool - Emits a load from constpool to materialize the
+  /// specified immediate.
+  void emitLoadConstPool(MachineBasicBlock &MBB,
+                         MachineBasicBlock::iterator &MBBI,
+                         unsigned DestReg, int Val,
+                         unsigned Pred, unsigned PredReg,
+                         const TargetInstrInfo *TII,
+                         DebugLoc dl) const;
+
+  /// Code Generation virtual methods...
+  const TargetRegisterClass *
+    getPhysicalRegisterRegClass(unsigned Reg, MVT VT = MVT::Other) const;
+
+  bool isReservedReg(const MachineFunction &MF, unsigned Reg) const;
+
+  bool requiresRegisterScavenging(const MachineFunction &MF) const;
+
+  bool hasReservedCallFrame(MachineFunction &MF) const;
+
+  void eliminateCallFramePseudoInstr(MachineFunction &MF,
+                                     MachineBasicBlock &MBB,
+                                     MachineBasicBlock::iterator I) const;
+
+  void eliminateFrameIndex(MachineBasicBlock::iterator II,
+                           int SPAdj, RegScavenger *RS = NULL) const;
+
+  void emitPrologue(MachineFunction &MF) const;
+  void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const;
+
+  void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
+                    int NumBytes, ARMCC::CondCodes Pred, unsigned PredReg,
+                    const TargetInstrInfo &TII, DebugLoc dl) const;
+};
+}
+
+#endif // THUMBREGISTERINFO_H