X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTarget%2FARM%2FThumb2InstrInfo.cpp;h=cf040c822de95a45f440c16ab794d09ad5ebac40;hb=9858a48afcd39d41ad7d424b159422370cffca84;hp=6103463e87be31aecab4fc3a6cc55c8f639fc3e0;hpb=446c428bf394b7113b0f18cbacb5e87b4efd1e14;p=oota-llvm.git

diff --git a/lib/Target/ARM/Thumb2InstrInfo.cpp b/lib/Target/ARM/Thumb2InstrInfo.cpp
index 6103463e87b..cf040c822de 100644
--- a/lib/Target/ARM/Thumb2InstrInfo.cpp
+++ b/lib/Target/ARM/Thumb2InstrInfo.cpp
@@ -1,4 +1,4 @@
-//===- Thumb2InstrInfo.cpp - Thumb-2 Instruction Information --------*- C++ -*-===//
+//===- Thumb2InstrInfo.cpp - Thumb-2 Instruction Information ----*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -11,17 +11,26 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "ARMInstrInfo.h"
+#include "Thumb2InstrInfo.h"
 #include "ARM.h"
-#include "ARMGenInstrInfo.inc"
+#include "ARMConstantPoolValue.h"
 #include "ARMMachineFunctionInfo.h"
+#include "Thumb2InstrInfo.h"
+#include "MCTargetDesc/ARMAddressingModes.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineMemOperand.h"
+#include "llvm/CodeGen/PseudoSourceValue.h"
 #include "llvm/ADT/SmallVector.h"
-#include "Thumb2InstrInfo.h"
+#include "llvm/Support/CommandLine.h"
 
 using namespace llvm;
 
+static cl::opt<bool>
+OldT2IfCvt("old-thumb2-ifcvt", cl::Hidden,
+           cl::desc("Use old-style Thumb2 if-conversion heuristics"),
+           cl::init(false));
+
 Thumb2InstrInfo::Thumb2InstrInfo(const ARMSubtarget &STI)
   : ARMBaseInstrInfo(STI), RI(*this, STI) {
 }
@@ -31,31 +40,273 @@ unsigned Thumb2InstrInfo::getUnindexedOpcode(unsigned Opc) const {
   return 0;
 }
 
-unsigned Thumb2InstrInfo::getOpcode(ARMII::Op Op) const {
-  switch (Op) {
-  case ARMII::ADDri: return ARM::t2ADDri;
-  case ARMII::ADDrs: return ARM::t2ADDrs;
-  case ARMII::ADDrr: return ARM::t2ADDrr;
-  case ARMII::B: return ARM::t2B;
-  case ARMII::Bcc: return ARM::t2Bcc;
-  case ARMII::BR_JTr: return ARM::t2BR_JTr;
-  case ARMII::BR_JTm: return ARM::t2BR_JTm;
-  case ARMII::BR_JTadd: return ARM::t2BR_JTadd;
-  case ARMII::BX_RET: return ARM::tBX_RET;
-  case ARMII::FCPYS: return ARM::FCPYS;
-  case ARMII::FCPYD: return ARM::FCPYD;
-  case ARMII::FLDD: return ARM::FLDD;
-  case ARMII::FLDS: return ARM::FLDS;
-  case ARMII::FSTD: return ARM::FSTD;
-  case ARMII::FSTS: return ARM::FSTS;
-  case ARMII::LDR: return ARM::LDR;   // FIXME
-  case ARMII::MOVr: return ARM::t2MOVr;
-  case ARMII::STR: return ARM::STR;   // FIXME
-  case ARMII::SUBri: return ARM::t2SUBri;
-  case ARMII::SUBrs: return ARM::t2SUBrs;
-  case ARMII::SUBrr: return ARM::t2SUBrr;
-  case ARMII::VMOVD: return ARM::VMOVD;
-  case ARMII::VMOVQ: return ARM::VMOVQ;
+void
+Thumb2InstrInfo::ReplaceTailWithBranchTo(MachineBasicBlock::iterator Tail,
+                                         MachineBasicBlock *NewDest) const {
+  MachineBasicBlock *MBB = Tail->getParent();
+  ARMFunctionInfo *AFI = MBB->getParent()->getInfo<ARMFunctionInfo>();
+  if (!AFI->hasITBlocks()) {
+    TargetInstrInfoImpl::ReplaceTailWithBranchTo(Tail, NewDest);
+    return;
+  }
+
+  // If the first instruction of Tail is predicated, we may have to update
+  // the IT instruction.
+  unsigned PredReg = 0;
+  ARMCC::CondCodes CC = llvm::getInstrPredicate(Tail, PredReg);
+  MachineBasicBlock::iterator MBBI = Tail;
+  if (CC != ARMCC::AL)
+    // Expecting at least the t2IT instruction before it.
+    --MBBI;
+
+  // Actually replace the tail.
+  TargetInstrInfoImpl::ReplaceTailWithBranchTo(Tail, NewDest);
+
+  // Fix up IT.
+  if (CC != ARMCC::AL) {
+    MachineBasicBlock::iterator E = MBB->begin();
+    unsigned Count = 4; // At most 4 instructions in an IT block.
+    while (Count && MBBI != E) {
+      if (MBBI->isDebugValue()) {
+        --MBBI;
+        continue;
+      }
+      if (MBBI->getOpcode() == ARM::t2IT) {
+        unsigned Mask = MBBI->getOperand(1).getImm();
+        if (Count == 4)
+          MBBI->eraseFromParent();
+        else {
+          unsigned MaskOn = 1 << Count;
+          unsigned MaskOff = ~(MaskOn - 1);
+          MBBI->getOperand(1).setImm((Mask & MaskOff) | MaskOn);
+        }
+        return;
+      }
+      --MBBI;
+      --Count;
+    }
+
+    // Ctrl flow can reach here if branch folding is run before IT block
+    // formation pass.
+  }
+}
+
+bool
+Thumb2InstrInfo::isLegalToSplitMBBAt(MachineBasicBlock &MBB,
+                                     MachineBasicBlock::iterator MBBI) const {
+  while (MBBI->isDebugValue()) {
+    ++MBBI;
+    if (MBBI == MBB.end())
+      return false;
+  }
+
+  unsigned PredReg = 0;
+  return llvm::getITInstrPredicate(MBBI, PredReg) == ARMCC::AL;
+}
+
+void Thumb2InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
+                                  MachineBasicBlock::iterator I, DebugLoc DL,
+                                  unsigned DestReg, unsigned SrcReg,
+                                  bool KillSrc) const {
+  // Handle SPR, DPR, and QPR copies.
+  if (!ARM::GPRRegClass.contains(DestReg, SrcReg))
+    return ARMBaseInstrInfo::copyPhysReg(MBB, I, DL, DestReg, SrcReg, KillSrc);
+
+  AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::tMOVr), DestReg)
+    .addReg(SrcReg, getKillRegState(KillSrc)));
+}
+
+void Thumb2InstrInfo::
+storeRegToStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
+                    unsigned SrcReg, bool isKill, int FI,
+                    const TargetRegisterClass *RC,
+                    const TargetRegisterInfo *TRI) const {
+  if (RC == ARM::GPRRegisterClass   || RC == ARM::tGPRRegisterClass ||
+      RC == ARM::tcGPRRegisterClass || RC == ARM::rGPRRegisterClass ||
+      RC == ARM::GPRnopcRegisterClass) {
+    DebugLoc DL;
+    if (I != MBB.end()) DL = I->getDebugLoc();
+
+    MachineFunction &MF = *MBB.getParent();
+    MachineFrameInfo &MFI = *MF.getFrameInfo();
+    MachineMemOperand *MMO =
+      MF.getMachineMemOperand(
+                      MachinePointerInfo(PseudoSourceValue::getFixedStack(FI)),
+                              MachineMemOperand::MOStore,
+                              MFI.getObjectSize(FI),
+                              MFI.getObjectAlignment(FI));
+    AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::t2STRi12))
+                   .addReg(SrcReg, getKillRegState(isKill))
+                   .addFrameIndex(FI).addImm(0).addMemOperand(MMO));
+    return;
+  }
+
+  ARMBaseInstrInfo::storeRegToStackSlot(MBB, I, SrcReg, isKill, FI, RC, TRI);
+}
+
+void Thumb2InstrInfo::
+loadRegFromStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
+                     unsigned DestReg, int FI,
+                     const TargetRegisterClass *RC,
+                     const TargetRegisterInfo *TRI) const {
+  if (RC == ARM::GPRRegisterClass   || RC == ARM::tGPRRegisterClass ||
+      RC == ARM::tcGPRRegisterClass || RC == ARM::rGPRRegisterClass ||
+      RC == ARM::GPRnopcRegisterClass) {
+    DebugLoc DL;
+    if (I != MBB.end()) DL = I->getDebugLoc();
+
+    MachineFunction &MF = *MBB.getParent();
+    MachineFrameInfo &MFI = *MF.getFrameInfo();
+    MachineMemOperand *MMO =
+      MF.getMachineMemOperand(
+                      MachinePointerInfo(PseudoSourceValue::getFixedStack(FI)),
+                              MachineMemOperand::MOLoad,
+                              MFI.getObjectSize(FI),
+                              MFI.getObjectAlignment(FI));
+    AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::t2LDRi12), DestReg)
+                   .addFrameIndex(FI).addImm(0).addMemOperand(MMO));
+    return;
+  }
+
+  ARMBaseInstrInfo::loadRegFromStackSlot(MBB, I, DestReg, FI, RC, TRI);
+}
+
+void llvm::emitT2RegPlusImmediate(MachineBasicBlock &MBB,
+                               MachineBasicBlock::iterator &MBBI, DebugLoc dl,
+                               unsigned DestReg, unsigned BaseReg, int NumBytes,
+                               ARMCC::CondCodes Pred, unsigned PredReg,
+                               const ARMBaseInstrInfo &TII, unsigned MIFlags) {
+  bool isSub = NumBytes < 0;
+  if (isSub) NumBytes = -NumBytes;
+
+  // If profitable, use a movw or movt to materialize the offset.
+  // FIXME: Use the scavenger to grab a scratch register.
+  if (DestReg != ARM::SP && DestReg != BaseReg &&
+      NumBytes >= 4096 &&
+      ARM_AM::getT2SOImmVal(NumBytes) == -1) {
+    bool Fits = false;
+    if (NumBytes < 65536) {
+      // Use a movw to materialize the 16-bit constant.
+      BuildMI(MBB, MBBI, dl, TII.get(ARM::t2MOVi16), DestReg)
+        .addImm(NumBytes)
+        .addImm((unsigned)Pred).addReg(PredReg).setMIFlags(MIFlags);
+      Fits = true;
+    } else if ((NumBytes & 0xffff) == 0) {
+      // Use a movt to materialize the 32-bit constant.
+      BuildMI(MBB, MBBI, dl, TII.get(ARM::t2MOVTi16), DestReg)
+        .addReg(DestReg)
+        .addImm(NumBytes >> 16)
+        .addImm((unsigned)Pred).addReg(PredReg).setMIFlags(MIFlags);
+      Fits = true;
+    }
+
+    if (Fits) {
+      if (isSub) {
+        BuildMI(MBB, MBBI, dl, TII.get(ARM::t2SUBrr), DestReg)
+          .addReg(BaseReg, RegState::Kill)
+          .addReg(DestReg, RegState::Kill)
+          .addImm((unsigned)Pred).addReg(PredReg).addReg(0)
+          .setMIFlags(MIFlags);
+      } else {
+        BuildMI(MBB, MBBI, dl, TII.get(ARM::t2ADDrr), DestReg)
+          .addReg(DestReg, RegState::Kill)
+          .addReg(BaseReg, RegState::Kill)
+          .addImm((unsigned)Pred).addReg(PredReg).addReg(0)
+          .setMIFlags(MIFlags);
+      }
+      return;
+    }
+  }
+
+  while (NumBytes) {
+    unsigned ThisVal = NumBytes;
+    unsigned Opc = 0;
+    if (DestReg == ARM::SP && BaseReg != ARM::SP) {
+      // mov sp, rn. Note t2MOVr cannot be used.
+      AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr),DestReg)
+        .addReg(BaseReg).setMIFlags(MIFlags));
+      BaseReg = ARM::SP;
+      continue;
+    }
+
+    bool HasCCOut = true;
+    if (BaseReg == ARM::SP) {
+      // sub sp, sp, #imm7
+      if (DestReg == ARM::SP && (ThisVal < ((1 << 7)-1) * 4)) {
+        assert((ThisVal & 3) == 0 && "Stack update is not multiple of 4?");
+        Opc = isSub ? ARM::tSUBspi : ARM::tADDspi;
+        AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
+          .addReg(BaseReg).addImm(ThisVal/4).setMIFlags(MIFlags));
+        NumBytes = 0;
+        continue;
+      }
+
+      // sub rd, sp, so_imm
+      Opc = isSub ? ARM::t2SUBri : ARM::t2ADDri;
+      if (ARM_AM::getT2SOImmVal(NumBytes) != -1) {
+        NumBytes = 0;
+      } else {
+        // FIXME: Move this to ARMAddressingModes.h?
+        unsigned RotAmt = CountLeadingZeros_32(ThisVal);
+        ThisVal = ThisVal & ARM_AM::rotr32(0xff000000U, RotAmt);
+        NumBytes &= ~ThisVal;
+        assert(ARM_AM::getT2SOImmVal(ThisVal) != -1 &&
+               "Bit extraction didn't work?");
+      }
+    } else {
+      assert(DestReg != ARM::SP && BaseReg != ARM::SP);
+      Opc = isSub ? ARM::t2SUBri : ARM::t2ADDri;
+      if (ARM_AM::getT2SOImmVal(NumBytes) != -1) {
+        NumBytes = 0;
+      } else if (ThisVal < 4096) {
+        Opc = isSub ? ARM::t2SUBri12 : ARM::t2ADDri12;
+        HasCCOut = false;
+        NumBytes = 0;
+      } else {
+        // FIXME: Move this to ARMAddressingModes.h?
+        unsigned RotAmt = CountLeadingZeros_32(ThisVal);
+        ThisVal = ThisVal & ARM_AM::rotr32(0xff000000U, RotAmt);
+        NumBytes &= ~ThisVal;
+        assert(ARM_AM::getT2SOImmVal(ThisVal) != -1 &&
+               "Bit extraction didn't work?");
+      }
+    }
+
+    // Build the new ADD / SUB.
+    MachineInstrBuilder MIB =
+      AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(Opc), DestReg)
+                     .addReg(BaseReg, RegState::Kill)
+                     .addImm(ThisVal)).setMIFlags(MIFlags);
+    if (HasCCOut)
+      AddDefaultCC(MIB);
+
+    BaseReg = DestReg;
+  }
+}
+
+static unsigned
+negativeOffsetOpcode(unsigned opcode)
+{
+  switch (opcode) {
+  case ARM::t2LDRi12:   return ARM::t2LDRi8;
+  case ARM::t2LDRHi12:  return ARM::t2LDRHi8;
+  case ARM::t2LDRBi12:  return ARM::t2LDRBi8;
+  case ARM::t2LDRSHi12: return ARM::t2LDRSHi8;
+  case ARM::t2LDRSBi12: return ARM::t2LDRSBi8;
+  case ARM::t2STRi12:   return ARM::t2STRi8;
+  case ARM::t2STRBi12:  return ARM::t2STRBi8;
+  case ARM::t2STRHi12:  return ARM::t2STRHi8;
+
+  case ARM::t2LDRi8:
+  case ARM::t2LDRHi8:
+  case ARM::t2LDRBi8:
+  case ARM::t2LDRSHi8:
+  case ARM::t2LDRSBi8:
+  case ARM::t2STRi8:
+  case ARM::t2STRBi8:
+  case ARM::t2STRHi8:
+    return opcode;
+
   default:
     break;
   }
@@ -63,27 +314,298 @@ unsigned Thumb2InstrInfo::getOpcode(ARMII::Op Op) const {
   return 0;
 }
 
-bool
-Thumb2InstrInfo::BlockHasNoFallThrough(const MachineBasicBlock &MBB) const {
-  if (MBB.empty()) return false;
+static unsigned
+positiveOffsetOpcode(unsigned opcode)
+{
+  switch (opcode) {
+  case ARM::t2LDRi8:   return ARM::t2LDRi12;
+  case ARM::t2LDRHi8:  return ARM::t2LDRHi12;
+  case ARM::t2LDRBi8:  return ARM::t2LDRBi12;
+  case ARM::t2LDRSHi8: return ARM::t2LDRSHi12;
+  case ARM::t2LDRSBi8: return ARM::t2LDRSBi12;
+  case ARM::t2STRi8:   return ARM::t2STRi12;
+  case ARM::t2STRBi8:  return ARM::t2STRBi12;
+  case ARM::t2STRHi8:  return ARM::t2STRHi12;
+
+  case ARM::t2LDRi12:
+  case ARM::t2LDRHi12:
+  case ARM::t2LDRBi12:
+  case ARM::t2LDRSHi12:
+  case ARM::t2LDRSBi12:
+  case ARM::t2STRi12:
+  case ARM::t2STRBi12:
+  case ARM::t2STRHi12:
+    return opcode;
+
+  default:
+    break;
+  }
+
+  return 0;
+}
+
+static unsigned
+immediateOffsetOpcode(unsigned opcode)
+{
+  switch (opcode) {
+  case ARM::t2LDRs:   return ARM::t2LDRi12;
+  case ARM::t2LDRHs:  return ARM::t2LDRHi12;
+  case ARM::t2LDRBs:  return ARM::t2LDRBi12;
+  case ARM::t2LDRSHs: return ARM::t2LDRSHi12;
+  case ARM::t2LDRSBs: return ARM::t2LDRSBi12;
+  case ARM::t2STRs:   return ARM::t2STRi12;
+  case ARM::t2STRBs:  return ARM::t2STRBi12;
+  case ARM::t2STRHs:  return ARM::t2STRHi12;
+
+  case ARM::t2LDRi12:
+  case ARM::t2LDRHi12:
+  case ARM::t2LDRBi12:
+  case ARM::t2LDRSHi12:
+  case ARM::t2LDRSBi12:
+  case ARM::t2STRi12:
+  case ARM::t2STRBi12:
+  case ARM::t2STRHi12:
+  case ARM::t2LDRi8:
+  case ARM::t2LDRHi8:
+  case ARM::t2LDRBi8:
+  case ARM::t2LDRSHi8:
+  case ARM::t2LDRSBi8:
+  case ARM::t2STRi8:
+  case ARM::t2STRBi8:
+  case ARM::t2STRHi8:
+    return opcode;
 
-  // FIXME
-  switch (MBB.back().getOpcode()) {
-  case ARM::t2LDM_RET:
-  case ARM::t2B:        // Uncond branch.
-  case ARM::t2BR_JTr:   // Jumptable branch.
-  case ARM::t2BR_JTm:   // Jumptable branch through mem.
-  case ARM::t2BR_JTadd: // Jumptable branch add to pc.
-    return true;
-  case ARM::tBX_RET:
-  case ARM::tBX_RET_vararg:
-  case ARM::tPOP_RET:
-  case ARM::tB:
-  case ARM::tBR_JTr:
-    return true;
   default:
     break;
   }
 
-  return false;
+  return 0;
+}
+
+bool llvm::rewriteT2FrameIndex(MachineInstr &MI, unsigned FrameRegIdx,
+                               unsigned FrameReg, int &Offset,
+                               const ARMBaseInstrInfo &TII) {
+  unsigned Opcode = MI.getOpcode();
+  const MCInstrDesc &Desc = MI.getDesc();
+  unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
+  bool isSub = false;
+
+  // Memory operands in inline assembly always use AddrModeT2_i12.
+  if (Opcode == ARM::INLINEASM)
+    AddrMode = ARMII::AddrModeT2_i12; // FIXME. mode for thumb2?
+
+  if (Opcode == ARM::t2ADDri || Opcode == ARM::t2ADDri12) {
+    Offset += MI.getOperand(FrameRegIdx+1).getImm();
+
+    unsigned PredReg;
+    if (Offset == 0 && getInstrPredicate(&MI, PredReg) == ARMCC::AL) {
+      // Turn it into a move.
+      MI.setDesc(TII.get(ARM::tMOVr));
+      MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
+      // Remove offset and remaining explicit predicate operands.
+      do MI.RemoveOperand(FrameRegIdx+1);
+      while (MI.getNumOperands() > FrameRegIdx+1);
+      MachineInstrBuilder MIB(&MI);
+      AddDefaultPred(MIB);
+      return true;
+    }
+
+    bool HasCCOut = Opcode != ARM::t2ADDri12;
+
+    if (Offset < 0) {
+      Offset = -Offset;
+      isSub = true;
+      MI.setDesc(TII.get(ARM::t2SUBri));
+    } else {
+      MI.setDesc(TII.get(ARM::t2ADDri));
+    }
+
+    // Common case: small offset, fits into instruction.
+    if (ARM_AM::getT2SOImmVal(Offset) != -1) {
+      MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
+      MI.getOperand(FrameRegIdx+1).ChangeToImmediate(Offset);
+      // Add cc_out operand if the original instruction did not have one.
+      if (!HasCCOut)
+        MI.addOperand(MachineOperand::CreateReg(0, false));
+      Offset = 0;
+      return true;
+    }
+    // Another common case: imm12.
+    if (Offset < 4096 &&
+        (!HasCCOut || MI.getOperand(MI.getNumOperands()-1).getReg() == 0)) {
+      unsigned NewOpc = isSub ? ARM::t2SUBri12 : ARM::t2ADDri12;
+      MI.setDesc(TII.get(NewOpc));
+      MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
+      MI.getOperand(FrameRegIdx+1).ChangeToImmediate(Offset);
+      // Remove the cc_out operand.
+      if (HasCCOut)
+        MI.RemoveOperand(MI.getNumOperands()-1);
+      Offset = 0;
+      return true;
+    }
+
+    // Otherwise, extract 8 adjacent bits from the immediate into this
+    // t2ADDri/t2SUBri.
+    unsigned RotAmt = CountLeadingZeros_32(Offset);
+    unsigned ThisImmVal = Offset & ARM_AM::rotr32(0xff000000U, RotAmt);
+
+    // We will handle these bits from offset, clear them.
+    Offset &= ~ThisImmVal;
+
+    assert(ARM_AM::getT2SOImmVal(ThisImmVal) != -1 &&
+           "Bit extraction didn't work?");
+    MI.getOperand(FrameRegIdx+1).ChangeToImmediate(ThisImmVal);
+    // Add cc_out operand if the original instruction did not have one.
+    if (!HasCCOut)
+      MI.addOperand(MachineOperand::CreateReg(0, false));
+
+  } else {
+
+    // AddrMode4 and AddrMode6 cannot handle any offset.
+    if (AddrMode == ARMII::AddrMode4 || AddrMode == ARMII::AddrMode6)
+      return false;
+
+    // AddrModeT2_so cannot handle any offset. If there is no offset
+    // register then we change to an immediate version.
+    unsigned NewOpc = Opcode;
+    if (AddrMode == ARMII::AddrModeT2_so) {
+      unsigned OffsetReg = MI.getOperand(FrameRegIdx+1).getReg();
+      if (OffsetReg != 0) {
+        MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
+        return Offset == 0;
+      }
+
+      MI.RemoveOperand(FrameRegIdx+1);
+      MI.getOperand(FrameRegIdx+1).ChangeToImmediate(0);
+      NewOpc = immediateOffsetOpcode(Opcode);
+      AddrMode = ARMII::AddrModeT2_i12;
+    }
+
+    unsigned NumBits = 0;
+    unsigned Scale = 1;
+    if (AddrMode == ARMII::AddrModeT2_i8 || AddrMode == ARMII::AddrModeT2_i12) {
+      // i8 supports only negative, and i12 supports only positive, so
+      // based on Offset sign convert Opcode to the appropriate
+      // instruction
+      Offset += MI.getOperand(FrameRegIdx+1).getImm();
+      if (Offset < 0) {
+        NewOpc = negativeOffsetOpcode(Opcode);
+        NumBits = 8;
+        isSub = true;
+        Offset = -Offset;
+      } else {
+        NewOpc = positiveOffsetOpcode(Opcode);
+        NumBits = 12;
+      }
+    } else if (AddrMode == ARMII::AddrMode5) {
+      // VFP address mode.
+      const MachineOperand &OffOp = MI.getOperand(FrameRegIdx+1);
+      int InstrOffs = ARM_AM::getAM5Offset(OffOp.getImm());
+      if (ARM_AM::getAM5Op(OffOp.getImm()) == ARM_AM::sub)
+        InstrOffs *= -1;
+      NumBits = 8;
+      Scale = 4;
+      Offset += InstrOffs * 4;
+      assert((Offset & (Scale-1)) == 0 && "Can't encode this offset!");
+      if (Offset < 0) {
+        Offset = -Offset;
+        isSub = true;
+      }
+    } else {
+      llvm_unreachable("Unsupported addressing mode!");
+    }
+
+    if (NewOpc != Opcode)
+      MI.setDesc(TII.get(NewOpc));
+
+    MachineOperand &ImmOp = MI.getOperand(FrameRegIdx+1);
+
+    // Attempt to fold address computation
+    // Common case: small offset, fits into instruction.
+    int ImmedOffset = Offset / Scale;
+    unsigned Mask = (1 << NumBits) - 1;
+    if ((unsigned)Offset <= Mask * Scale) {
+      // Replace the FrameIndex with fp/sp
+      MI.getOperand(FrameRegIdx).ChangeToRegister(FrameReg, false);
+      if (isSub) {
+        if (AddrMode == ARMII::AddrMode5)
+          // FIXME: Not consistent.
+          ImmedOffset |= 1 << NumBits;
+        else
+          ImmedOffset = -ImmedOffset;
+      }
+      ImmOp.ChangeToImmediate(ImmedOffset);
+      Offset = 0;
+      return true;
+    }
+
+    // Otherwise, offset doesn't fit. Pull in what we can to simplify
+    ImmedOffset = ImmedOffset & Mask;
+    if (isSub) {
+      if (AddrMode == ARMII::AddrMode5)
+        // FIXME: Not consistent.
+        ImmedOffset |= 1 << NumBits;
+      else {
+        ImmedOffset = -ImmedOffset;
+        if (ImmedOffset == 0)
+          // Change the opcode back if the encoded offset is zero.
+          MI.setDesc(TII.get(positiveOffsetOpcode(NewOpc)));
+      }
+    }
+    ImmOp.ChangeToImmediate(ImmedOffset);
+    Offset &= ~(Mask*Scale);
+  }
+
+  Offset = (isSub) ? -Offset : Offset;
+  return Offset == 0;
+}
+
+/// scheduleTwoAddrSource - Schedule the copy / re-mat of the source of the
+/// two-addrss instruction inserted by two-address pass.
+void
+Thumb2InstrInfo::scheduleTwoAddrSource(MachineInstr *SrcMI,
+                                       MachineInstr *UseMI,
+                                       const TargetRegisterInfo &TRI) const {
+  if (SrcMI->getOpcode() != ARM::tMOVr || SrcMI->getOperand(1).isKill())
+    return;
+
+  unsigned PredReg = 0;
+  ARMCC::CondCodes CC = llvm::getInstrPredicate(UseMI, PredReg);
+  if (CC == ARMCC::AL || PredReg != ARM::CPSR)
+    return;
+
+  // Schedule the copy so it doesn't come between previous instructions
+  // and UseMI which can form an IT block.
+  unsigned SrcReg = SrcMI->getOperand(1).getReg();
+  ARMCC::CondCodes OCC = ARMCC::getOppositeCondition(CC);
+  MachineBasicBlock *MBB = UseMI->getParent();
+  MachineBasicBlock::iterator MBBI = SrcMI;
+  unsigned NumInsts = 0;
+  while (--MBBI != MBB->begin()) {
+    if (MBBI->isDebugValue())
+      continue;
+
+    MachineInstr *NMI = &*MBBI;
+    ARMCC::CondCodes NCC = llvm::getInstrPredicate(NMI, PredReg);
+    if (!(NCC == CC || NCC == OCC) ||
+        NMI->modifiesRegister(SrcReg, &TRI) ||
+        NMI->definesRegister(ARM::CPSR))
+      break;
+    if (++NumInsts == 4)
+      // Too many in a row!
+      return;
+  }
+
+  if (NumInsts) {
+    MBB->remove(SrcMI);
+    MBB->insert(++MBBI, SrcMI);
+  }
+}
+
+ARMCC::CondCodes
+llvm::getITInstrPredicate(const MachineInstr *MI, unsigned &PredReg) {
+  unsigned Opc = MI->getOpcode();
+  if (Opc == ARM::tBcc || Opc == ARM::t2Bcc)
+    return ARMCC::AL;
+  return llvm::getInstrPredicate(MI, PredReg);
 }