lib/Target/ARM/ARMAsmPrinter.cpp

//===-- ARMAsmPrinter.cpp - ARM LLVM assembly writer ----------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the "Instituto Nokia de Tecnologia" and
// is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains a printer that converts from our internal representation
// of machine-dependent LLVM code to GAS-format ARM assembly language.
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "asm-printer"
#include "ARM.h"
#include "ARMTargetMachine.h"
#include "ARMAddressingModes.h"
#include "ARMConstantPoolValue.h"
#include "ARMMachineFunctionInfo.h"
#include "llvm/Constants.h"
#include "llvm/Module.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/DwarfWriter.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/Target/TargetAsmInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Mangler.h"
#include "llvm/Support/MathExtras.h"
#include <cctype>
#include <iostream>
using namespace llvm;

STATISTIC(EmittedInsts, "Number of machine instrs printed");

namespace {
  struct VISIBILITY_HIDDEN ARMAsmPrinter : public AsmPrinter {
    ARMAsmPrinter(std::ostream &O, TargetMachine &TM, const TargetAsmInfo *T)
      : AsmPrinter(O, TM, T), DW(O, this, T), AFI(NULL), InCPMode(false) {
      Subtarget = &TM.getSubtarget<ARMSubtarget>();
    }

    DwarfWriter DW;

    /// Subtarget - Keep a pointer to the ARMSubtarget around so that we can
    /// make the right decision when printing asm code for different targets.
    const ARMSubtarget *Subtarget;

    /// AFI - Keep a pointer to ARMFunctionInfo for the current
    /// MachineFunction
    ARMFunctionInfo *AFI;

    /// We name each basic block in a Function with a unique number, so
    /// that we can consistently refer to them later. This is cleared
    /// at the beginning of each call to runOnMachineFunction().
    ///
    typedef std::map<const Value *, unsigned> ValueMapTy;
    ValueMapTy NumberForBB;

    /// Keeps the set of GlobalValues that require non-lazy-pointers for
    /// indirect access.
    std::set<std::string> GVNonLazyPtrs;

    /// Keeps the set of external function GlobalAddresses that the asm
    /// printer should generate stubs for.
    std::set<std::string> FnStubs;

    /// True if asm printer is printing a series of CONSTPOOL_ENTRY.
    bool InCPMode;
    
    virtual const char *getPassName() const {
      return "ARM Assembly Printer";
    }

    void printOperand(const MachineInstr *MI, int opNum,
                      const char *Modifier = 0);
    void printSOImmOperand(const MachineInstr *MI, int opNum);
    void printSORegOperand(const MachineInstr *MI, int opNum);
    void printAddrMode2Operand(const MachineInstr *MI, int OpNo);
    void printAddrMode2OffsetOperand(const MachineInstr *MI, int OpNo);
    void printAddrMode3Operand(const MachineInstr *MI, int OpNo);
    void printAddrMode3OffsetOperand(const MachineInstr *MI, int OpNo);
    void printAddrMode4Operand(const MachineInstr *MI, int OpNo,
                               const char *Modifier = 0);
    void printAddrMode5Operand(const MachineInstr *MI, int OpNo,
                               const char *Modifier = 0);
    void printAddrModePCOperand(const MachineInstr *MI, int OpNo,
                                const char *Modifier = 0);
    void printThumbAddrModeRROperand(const MachineInstr *MI, int OpNo);
    void printThumbAddrModeRI5Operand(const MachineInstr *MI, int OpNo,
                                      unsigned Scale);
    void printThumbAddrModeS1Operand(const MachineInstr *MI, int OpNo);
    void printThumbAddrModeS2Operand(const MachineInstr *MI, int OpNo);
    void printThumbAddrModeS4Operand(const MachineInstr *MI, int OpNo);
    void printThumbAddrModeSPOperand(const MachineInstr *MI, int OpNo);
    void printCCOperand(const MachineInstr *MI, int opNum);
    void printPCLabel(const MachineInstr *MI, int opNum);
    void printRegisterList(const MachineInstr *MI, int opNum);
    void printCPInstOperand(const MachineInstr *MI, int opNum,
                            const char *Modifier);
    void printJTBlockOperand(const MachineInstr *MI, int opNum);

    virtual bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                                 unsigned AsmVariant, const char *ExtraCode);

    bool printInstruction(const MachineInstr *MI);  // autogenerated.
    void printMachineInstruction(const MachineInstr *MI);
    bool runOnMachineFunction(MachineFunction &F);
    bool doInitialization(Module &M);
    bool doFinalization(Module &M);

    virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV) {
      printDataDirective(MCPV->getType());

      ARMConstantPoolValue *ACPV = (ARMConstantPoolValue*)MCPV;
      GlobalValue *GV = ACPV->getGV();
      std::string Name = GV ? Mang->getValueName(GV) : TAI->getGlobalPrefix();
      if (!GV)
        Name += ACPV->getSymbol();
      if (ACPV->isNonLazyPointer()) {
        GVNonLazyPtrs.insert(Name);
        O << TAI->getPrivateGlobalPrefix() << Name << "$non_lazy_ptr";
      } else if (ACPV->isStub()) {
        FnStubs.insert(Name);
        O << TAI->getPrivateGlobalPrefix() << Name << "$stub";
      } else
        O << Name;
      if (ACPV->getPCAdjustment() != 0)
        O << "-(" << TAI->getPrivateGlobalPrefix() << "PC"
          << utostr(ACPV->getLabelId())
          << "+" << (unsigned)ACPV->getPCAdjustment() << ")";
      O << "\n";

      // If the constant pool value is a extern weak symbol, remember to emit
      // the weak reference.
      if (GV && GV->hasExternalWeakLinkage())
        ExtWeakSymbols.insert(GV);
    }
    
    void getAnalysisUsage(AnalysisUsage &AU) const {
      AU.setPreservesAll();
      AU.addRequired<MachineModuleInfo>();
    }
  };
} // end of anonymous namespace

#include "ARMGenAsmWriter.inc"

/// createARMCodePrinterPass - Returns a pass that prints the ARM
/// assembly code for a MachineFunction to the given output stream,
/// using the given target machine description.  This should work
/// regardless of whether the function is in SSA form.
///
FunctionPass *llvm::createARMCodePrinterPass(std::ostream &o,
                                             ARMTargetMachine &tm) {
  return new ARMAsmPrinter(o, tm, tm.getTargetAsmInfo());
}

/// runOnMachineFunction - This uses the printInstruction()
/// method to print assembly for each instruction.
///
bool ARMAsmPrinter::runOnMachineFunction(MachineFunction &MF) {
  AFI = MF.getInfo<ARMFunctionInfo>();

  if (Subtarget->isTargetDarwin()) {
    DW.SetModuleInfo(&getAnalysis<MachineModuleInfo>());
  }

  SetupMachineFunction(MF);
  O << "\n";

  // NOTE: we don't print out constant pools here, they are handled as
  // instructions.

  O << "\n";
  // Print out labels for the function.
  const Function *F = MF.getFunction();
  switch (F->getLinkage()) {
  default: assert(0 && "Unknown linkage type!");
  case Function::InternalLinkage:
    SwitchToTextSection("\t.text", F);
    break;
  case Function::ExternalLinkage:
    SwitchToTextSection("\t.text", F);
    O << "\t.globl\t" << CurrentFnName << "\n";
    break;
  case Function::WeakLinkage:
  case Function::LinkOnceLinkage:
    if (Subtarget->isTargetDarwin()) {
      SwitchToTextSection(
                ".section __TEXT,__textcoal_nt,coalesced,pure_instructions", F);
      O << "\t.globl\t" << CurrentFnName << "\n";
      O << "\t.weak_definition\t" << CurrentFnName << "\n";
    } else {
      O << TAI->getWeakRefDirective() << CurrentFnName << "\n";
    }
    break;
  }

  if (AFI->isThumbFunction()) {
    EmitAlignment(1, F);
    O << "\t.code\t16\n";
    O << "\t.thumb_func";
    if (Subtarget->isTargetDarwin())
      O << "\t" << CurrentFnName;
    O << "\n";
    InCPMode = false;
  } else
    EmitAlignment(2, F);

  O << CurrentFnName << ":\n";
  if (Subtarget->isTargetDarwin()) {
    // Emit pre-function debug information.
    DW.BeginFunction(&MF);
  }

  // Print out code for the function.
  for (MachineFunction::const_iterator I = MF.begin(), E = MF.end();
       I != E; ++I) {
    // Print a label for the basic block.
    if (I != MF.begin()) {
      printBasicBlockLabel(I, true);
      O << '\n';
    }
    for (MachineBasicBlock::const_iterator II = I->begin(), E = I->end();
         II != E; ++II) {
      // Print the assembly for the instruction.
      printMachineInstruction(II);
    }
  }

  if (TAI->hasDotTypeDotSizeDirective())
    O << "\t.size " << CurrentFnName << ", .-" << CurrentFnName << "\n";

  if (Subtarget->isTargetDarwin()) {
    // Emit post-function debug information.
    DW.EndFunction();
  }

  return false;
}

void ARMAsmPrinter::printOperand(const MachineInstr *MI, int opNum,
                                 const char *Modifier) {
  const MachineOperand &MO = MI->getOperand(opNum);
  switch (MO.getType()) {
  case MachineOperand::MO_Register:
    if (MRegisterInfo::isPhysicalRegister(MO.getReg()))
      O << TM.getRegisterInfo()->get(MO.getReg()).Name;
    else
      assert(0 && "not implemented");
    break;
  case MachineOperand::MO_Immediate: {
    if (!Modifier || strcmp(Modifier, "no_hash") != 0)
      O << "#";

    O << (int)MO.getImmedValue();
    break;
  }
  case MachineOperand::MO_MachineBasicBlock:
    printBasicBlockLabel(MO.getMachineBasicBlock());
    return;
  case MachineOperand::MO_GlobalAddress: {
    bool isCallOp = Modifier && !strcmp(Modifier, "call");
    GlobalValue *GV = MO.getGlobal();
    std::string Name = Mang->getValueName(GV);
    bool isExt = (GV->isDeclaration() || GV->hasWeakLinkage() ||
                  GV->hasLinkOnceLinkage());
    if (isExt && isCallOp && Subtarget->isTargetDarwin() &&
        TM.getRelocationModel() != Reloc::Static) {
      O << TAI->getPrivateGlobalPrefix() << Name << "$stub";
      FnStubs.insert(Name);
    } else
      O << Name;

    if (GV->hasExternalWeakLinkage())
      ExtWeakSymbols.insert(GV);
    break;
  }
  case MachineOperand::MO_ExternalSymbol: {
    bool isCallOp = Modifier && !strcmp(Modifier, "call");
    std::string Name(TAI->getGlobalPrefix());
    Name += MO.getSymbolName();
    if (isCallOp && Subtarget->isTargetDarwin() &&
        TM.getRelocationModel() != Reloc::Static) {
      O << TAI->getPrivateGlobalPrefix() << Name << "$stub";
      FnStubs.insert(Name);
    } else
      O << Name;
    break;
  }
  case MachineOperand::MO_ConstantPoolIndex:
    O << TAI->getPrivateGlobalPrefix() << "CPI" << getFunctionNumber()
      << '_' << MO.getConstantPoolIndex();
    break;
  case MachineOperand::MO_JumpTableIndex:
    O << TAI->getPrivateGlobalPrefix() << "JTI" << getFunctionNumber()
      << '_' << MO.getJumpTableIndex();
    break;
  default:
    O << "<unknown operand type>"; abort (); break;
  }
}

/// printSOImmOperand - SOImm is 4-bit rotate amount in bits 8-11 with 8-bit
/// immediate in bits 0-7.
void ARMAsmPrinter::printSOImmOperand(const MachineInstr *MI, int OpNum) {
  const MachineOperand &MO = MI->getOperand(OpNum);
  assert(MO.isImmediate() && (MO.getImmedValue() < (1 << 12)) &&
         "Not a valid so_imm value!");
  unsigned Imm = ARM_AM::getSOImmValImm(MO.getImmedValue());
  unsigned Rot = ARM_AM::getSOImmValRot(MO.getImmedValue());
  
  // Print low-level immediate formation info, per
  // A5.1.3: "Data-processing operands - Immediate".
  if (Rot) {
    O << "#" << Imm << ", " << Rot;
    // Pretty printed version.
    O << ' ' << TAI->getCommentString() << ' ' << (int)ARM_AM::rotr32(Imm, Rot);
  } else {
    O << "#" << Imm;
  }
}

// so_reg is a 4-operand unit corresponding to register forms of the A5.1
// "Addressing Mode 1 - Data-processing operands" forms.  This includes:
//    REG 0   0    - e.g. R5
//    REG REG 0,SH_OPC     - e.g. R5, ROR R3
//    REG 0   IMM,SH_OPC  - e.g. R5, LSL #3
void ARMAsmPrinter::printSORegOperand(const MachineInstr *MI, int Op) {
  const MachineOperand &MO1 = MI->getOperand(Op);
  const MachineOperand &MO2 = MI->getOperand(Op+1);
  const MachineOperand &MO3 = MI->getOperand(Op+2);

  assert(MRegisterInfo::isPhysicalRegister(MO1.getReg()));
  O << TM.getRegisterInfo()->get(MO1.getReg()).Name;

  // Print the shift opc.
  O << ", "
    << ARM_AM::getShiftOpcStr(ARM_AM::getSORegShOp(MO3.getImmedValue()))
    << " ";

  if (MO2.getReg()) {
    assert(MRegisterInfo::isPhysicalRegister(MO2.getReg()));
    O << TM.getRegisterInfo()->get(MO2.getReg()).Name;
    assert(ARM_AM::getSORegOffset(MO3.getImm()) == 0);
  } else {
    O << "#" << ARM_AM::getSORegOffset(MO3.getImm());
  }
}

void ARMAsmPrinter::printAddrMode2Operand(const MachineInstr *MI, int Op) {
  const MachineOperand &MO1 = MI->getOperand(Op);
  const MachineOperand &MO2 = MI->getOperand(Op+1);
  const MachineOperand &MO3 = MI->getOperand(Op+2);

  if (!MO1.isRegister()) {   // FIXME: This is for CP entries, but isn't right.
    printOperand(MI, Op);
    return;
  }

  O << "[" << TM.getRegisterInfo()->get(MO1.getReg()).Name;

  if (!MO2.getReg()) {
    if (ARM_AM::getAM2Offset(MO3.getImm()))  // Don't print +0.
      O << ", #"
        << (char)ARM_AM::getAM2Op(MO3.getImm())
        << ARM_AM::getAM2Offset(MO3.getImm());
    O << "]";
    return;
  }

  O << ", "
    << (char)ARM_AM::getAM2Op(MO3.getImm())
    << TM.getRegisterInfo()->get(MO2.getReg()).Name;
  
  if (unsigned ShImm = ARM_AM::getAM2Offset(MO3.getImm()))
    O << ", "
      << ARM_AM::getShiftOpcStr(ARM_AM::getAM2ShiftOpc(MO3.getImmedValue()))
      << " #" << ShImm;
  O << "]";
}

void ARMAsmPrinter::printAddrMode2OffsetOperand(const MachineInstr *MI, int Op){
  const MachineOperand &MO1 = MI->getOperand(Op);
  const MachineOperand &MO2 = MI->getOperand(Op+1);

  if (!MO1.getReg()) {
    if (ARM_AM::getAM2Offset(MO2.getImm()))  // Don't print +0.
      O << "#"
        << (char)ARM_AM::getAM2Op(MO2.getImm())
        << ARM_AM::getAM2Offset(MO2.getImm());
    return;
  }

  O << (char)ARM_AM::getAM2Op(MO2.getImm())
    << TM.getRegisterInfo()->get(MO1.getReg()).Name;
  
  if (unsigned ShImm = ARM_AM::getAM2Offset(MO2.getImm()))
    O << ", "
      << ARM_AM::getShiftOpcStr(ARM_AM::getAM2ShiftOpc(MO2.getImmedValue()))
      << " #" << ShImm;
}

void ARMAsmPrinter::printAddrMode3Operand(const MachineInstr *MI, int Op) {
  const MachineOperand &MO1 = MI->getOperand(Op);
  const MachineOperand &MO2 = MI->getOperand(Op+1);
  const MachineOperand &MO3 = MI->getOperand(Op+2);
  
  assert(MRegisterInfo::isPhysicalRegister(MO1.getReg()));
  O << "[" << TM.getRegisterInfo()->get(MO1.getReg()).Name;

  if (MO2.getReg()) {
    O << ", "
      << (char)ARM_AM::getAM3Op(MO3.getImm())
      << TM.getRegisterInfo()->get(MO2.getReg()).Name
      << "]";
    return;
  }
  
  if (unsigned ImmOffs = ARM_AM::getAM3Offset(MO3.getImm()))
    O << ", #"
      << (char)ARM_AM::getAM3Op(MO3.getImm())
      << ImmOffs;
  O << "]";
}

void ARMAsmPrinter::printAddrMode3OffsetOperand(const MachineInstr *MI, int Op){
  const MachineOperand &MO1 = MI->getOperand(Op);
  const MachineOperand &MO2 = MI->getOperand(Op+1);

  if (MO1.getReg()) {
    O << (char)ARM_AM::getAM3Op(MO2.getImm())
      << TM.getRegisterInfo()->get(MO1.getReg()).Name;
    return;
  }

  unsigned ImmOffs = ARM_AM::getAM3Offset(MO2.getImm());
  O << "#"
  << (char)ARM_AM::getAM3Op(MO2.getImm())
    << ImmOffs;
}
  
void ARMAsmPrinter::printAddrMode4Operand(const MachineInstr *MI, int Op,
                                          const char *Modifier) {
  const MachineOperand &MO1 = MI->getOperand(Op);
  const MachineOperand &MO2 = MI->getOperand(Op+1);
  ARM_AM::AMSubMode Mode = ARM_AM::getAM4SubMode(MO2.getImm());
  if (Modifier && strcmp(Modifier, "submode") == 0) {
    if (MO1.getReg() == ARM::SP) {
      bool isLDM = (MI->getOpcode() == ARM::LDM ||
                    MI->getOpcode() == ARM::LDM_RET);
      O << ARM_AM::getAMSubModeAltStr(Mode, isLDM);
    } else
      O << ARM_AM::getAMSubModeStr(Mode);
  } else {
    printOperand(MI, Op);
    if (ARM_AM::getAM4WBFlag(MO2.getImm()))
      O << "!";
  }
}

void ARMAsmPrinter::printAddrMode5Operand(const MachineInstr *MI, int Op,
                                          const char *Modifier) {
  const MachineOperand &MO1 = MI->getOperand(Op);
  const MachineOperand &MO2 = MI->getOperand(Op+1);

  if (!MO1.isRegister()) {   // FIXME: This is for CP entries, but isn't right.
    printOperand(MI, Op);
    return;
  }
  
  assert(MRegisterInfo::isPhysicalRegister(MO1.getReg()));

  if (Modifier && strcmp(Modifier, "submode") == 0) {
    ARM_AM::AMSubMode Mode = ARM_AM::getAM5SubMode(MO2.getImm());
    if (MO1.getReg() == ARM::SP) {
      bool isFLDM = (MI->getOpcode() == ARM::FLDMD ||
                     MI->getOpcode() == ARM::FLDMS);
      O << ARM_AM::getAMSubModeAltStr(Mode, isFLDM);
    } else
      O << ARM_AM::getAMSubModeStr(Mode);
    return;
  } else if (Modifier && strcmp(Modifier, "base") == 0) {
    // Used for FSTM{D|S} and LSTM{D|S} operations.
    O << TM.getRegisterInfo()->get(MO1.getReg()).Name;
    if (ARM_AM::getAM5WBFlag(MO2.getImm()))
      O << "!";
    return;
  }
  
  O << "[" << TM.getRegisterInfo()->get(MO1.getReg()).Name;
  
  if (unsigned ImmOffs = ARM_AM::getAM5Offset(MO2.getImm())) {
    O << ", #"
      << (char)ARM_AM::getAM5Op(MO2.getImm())
      << ImmOffs*4;
  }
  O << "]";
}

void ARMAsmPrinter::printAddrModePCOperand(const MachineInstr *MI, int Op,
                                           const char *Modifier) {
  if (Modifier && strcmp(Modifier, "label") == 0) {
    printPCLabel(MI, Op+1);
    return;
  }

  const MachineOperand &MO1 = MI->getOperand(Op);
  assert(MRegisterInfo::isPhysicalRegister(MO1.getReg()));
  O << "[pc, +" << TM.getRegisterInfo()->get(MO1.getReg()).Name << "]";
}

void
ARMAsmPrinter::printThumbAddrModeRROperand(const MachineInstr *MI, int Op) {
  const MachineOperand &MO1 = MI->getOperand(Op);
  const MachineOperand &MO2 = MI->getOperand(Op+1);
  O << "[" << TM.getRegisterInfo()->get(MO1.getReg()).Name;
  O << ", " << TM.getRegisterInfo()->get(MO2.getReg()).Name << "]";
}

void
ARMAsmPrinter::printThumbAddrModeRI5Operand(const MachineInstr *MI, int Op,
                                            unsigned Scale) {
  const MachineOperand &MO1 = MI->getOperand(Op);
  const MachineOperand &MO2 = MI->getOperand(Op+1);
  const MachineOperand &MO3 = MI->getOperand(Op+2);

  if (!MO1.isRegister()) {   // FIXME: This is for CP entries, but isn't right.
    printOperand(MI, Op);
    return;
  }

  O << "[" << TM.getRegisterInfo()->get(MO1.getReg()).Name;
  if (MO3.getReg())
    O << ", " << TM.getRegisterInfo()->get(MO3.getReg()).Name;
  else if (unsigned ImmOffs = MO2.getImm()) {
    O << ", #" << ImmOffs;
    if (Scale > 1)
      O << " * " << Scale;
  }
  O << "]";
}

void
ARMAsmPrinter::printThumbAddrModeS1Operand(const MachineInstr *MI, int Op) {
  printThumbAddrModeRI5Operand(MI, Op, 1);
}
void
ARMAsmPrinter::printThumbAddrModeS2Operand(const MachineInstr *MI, int Op) {
  printThumbAddrModeRI5Operand(MI, Op, 2);
}
void
ARMAsmPrinter::printThumbAddrModeS4Operand(const MachineInstr *MI, int Op) {
  printThumbAddrModeRI5Operand(MI, Op, 4);
}

void ARMAsmPrinter::printThumbAddrModeSPOperand(const MachineInstr *MI,int Op) {
  const MachineOperand &MO1 = MI->getOperand(Op);
  const MachineOperand &MO2 = MI->getOperand(Op+1);
  O << "[" << TM.getRegisterInfo()->get(MO1.getReg()).Name;
  if (unsigned ImmOffs = MO2.getImm())
    O << ", #" << ImmOffs << " * 4";
  O << "]";
}

void ARMAsmPrinter::printCCOperand(const MachineInstr *MI, int opNum) {
  int CC = (int)MI->getOperand(opNum).getImmedValue();
  O << ARMCondCodeToString((ARMCC::CondCodes)CC);
}

void ARMAsmPrinter::printPCLabel(const MachineInstr *MI, int opNum) {
  int Id = (int)MI->getOperand(opNum).getImmedValue();
  O << TAI->getPrivateGlobalPrefix() << "PC" << Id;
}

void ARMAsmPrinter::printRegisterList(const MachineInstr *MI, int opNum) {
  O << "{";
  for (unsigned i = opNum, e = MI->getNumOperands(); i != e; ++i) {
    printOperand(MI, i);
    if (i != e-1) O << ", ";
  }
  O << "}";
}

void ARMAsmPrinter::printCPInstOperand(const MachineInstr *MI, int OpNo,
                                       const char *Modifier) {
  assert(Modifier && "This operand only works with a modifier!");
  // There are two aspects to a CONSTANTPOOL_ENTRY operand, the label and the
  // data itself.
  if (!strcmp(Modifier, "label")) {
    unsigned ID = MI->getOperand(OpNo).getImm();
    O << TAI->getPrivateGlobalPrefix() << "CPI" << getFunctionNumber()
      << '_' << ID << ":\n";
  } else {
    assert(!strcmp(Modifier, "cpentry") && "Unknown modifier for CPE");
    unsigned CPI = MI->getOperand(OpNo).getConstantPoolIndex();

    const MachineConstantPoolEntry &MCPE =  // Chasing pointers is fun?
      MI->getParent()->getParent()->getConstantPool()->getConstants()[CPI];
    
    if (MCPE.isMachineConstantPoolEntry())
      EmitMachineConstantPoolValue(MCPE.Val.MachineCPVal);
    else
      EmitGlobalConstant(MCPE.Val.ConstVal);
  }
}

void ARMAsmPrinter::printJTBlockOperand(const MachineInstr *MI, int OpNo) {
  const MachineOperand &MO1 = MI->getOperand(OpNo);
  const MachineOperand &MO2 = MI->getOperand(OpNo+1); // Unique Id
  unsigned JTI = MO1.getJumpTableIndex();
  O << TAI->getPrivateGlobalPrefix() << "JTI" << getFunctionNumber()
    << '_' << JTI << '_' << MO2.getImmedValue() << ":\n";

  const char *JTEntryDirective = TAI->getJumpTableDirective();
  if (!JTEntryDirective)
    JTEntryDirective = TAI->getData32bitsDirective();

  const MachineFunction *MF = MI->getParent()->getParent();
  MachineJumpTableInfo *MJTI = MF->getJumpTableInfo();
  const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
  const std::vector<MachineBasicBlock*> &JTBBs = JT[JTI].MBBs;
  bool UseSet= TAI->getSetDirective() && TM.getRelocationModel() == Reloc::PIC_;
  std::set<MachineBasicBlock*> JTSets;
  for (unsigned i = 0, e = JTBBs.size(); i != e; ++i) {
    MachineBasicBlock *MBB = JTBBs[i];
    if (UseSet && JTSets.insert(MBB).second)
      printSetLabel(JTI, MO2.getImmedValue(), MBB);

    O << JTEntryDirective << ' ';
    if (UseSet)
      O << TAI->getPrivateGlobalPrefix() << getFunctionNumber()
        << '_' << JTI << '_' << MO2.getImmedValue()
        << "_set_" << MBB->getNumber();
    else if (TM.getRelocationModel() == Reloc::PIC_) {
      printBasicBlockLabel(MBB, false, false);
      // If the arch uses custom Jump Table directives, don't calc relative to JT
      if (!TAI->getJumpTableDirective()) 
        O << '-' << TAI->getPrivateGlobalPrefix() << "JTI"
          << getFunctionNumber() << '_' << JTI << '_' << MO2.getImmedValue();
    } else
      printBasicBlockLabel(MBB, false, false);
    if (i != e-1)
      O << '\n';
  }
}


bool ARMAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                                    unsigned AsmVariant, const char *ExtraCode){
  // Does this asm operand have a single letter operand modifier?
  if (ExtraCode && ExtraCode[0]) {
    if (ExtraCode[1] != 0) return true; // Unknown modifier.
    
    switch (ExtraCode[0]) {
    default: return true;  // Unknown modifier.
    case 'Q':
      if (TM.getTargetData()->isLittleEndian())
        break;
      // Fallthrough
    case 'R':
      if (TM.getTargetData()->isBigEndian())
        break;
      // Fallthrough
    case 'H': // Write second word of DI / DF reference.  
      // Verify that this operand has two consecutive registers.
      if (!MI->getOperand(OpNo).isRegister() ||
          OpNo+1 == MI->getNumOperands() ||
          !MI->getOperand(OpNo+1).isRegister())
        return true;
      ++OpNo;   // Return the high-part.
    }
  }
  
  printOperand(MI, OpNo);
  return false;
}

void ARMAsmPrinter::printMachineInstruction(const MachineInstr *MI) {
  ++EmittedInsts;

  int Opc = MI->getOpcode();
  switch (Opc) {
  case ARM::CONSTPOOL_ENTRY:
    if (!InCPMode && AFI->isThumbFunction()) {
      EmitAlignment(2);
      InCPMode = true;
    }
    break;
  default: {
    if (InCPMode && AFI->isThumbFunction())
      InCPMode = false;
    switch (Opc) {
    case ARM::PICADD:
    case ARM::PICLD:
    case ARM::tPICADD:
      break;
    default:
      O << "\t";
      break;
    }
  }}

  // Call the autogenerated instruction printer routines.
  printInstruction(MI);
}

bool ARMAsmPrinter::doInitialization(Module &M) {
  if (Subtarget->isTargetDarwin()) {
    // Emit initial debug information.
    DW.BeginModule(&M);
  }
  
  return AsmPrinter::doInitialization(M);
}

bool ARMAsmPrinter::doFinalization(Module &M) {
  const TargetData *TD = TM.getTargetData();

  for (Module::const_global_iterator I = M.global_begin(), E = M.global_end();
       I != E; ++I) {
    if (!I->hasInitializer())   // External global require no code
      continue;

    if (EmitSpecialLLVMGlobal(I)) {
      if (Subtarget->isTargetDarwin() &&
          TM.getRelocationModel() == Reloc::Static) {
        if (I->getName() == "llvm.global_ctors")
          O << ".reference .constructors_used\n";
        else if (I->getName() == "llvm.global_dtors")
          O << ".reference .destructors_used\n";
      }
      continue;
    }

    std::string name = Mang->getValueName(I);
    Constant *C = I->getInitializer();
    unsigned Size = TD->getTypeSize(C->getType());
    unsigned Align = TD->getPreferredAlignmentLog(I);

    if (I->hasHiddenVisibility())
      if (const char *Directive = TAI->getHiddenDirective())
        O << Directive << name << "\n";
    if (Subtarget->isTargetELF())
      O << "\t.type " << name << ",%object\n";
    
    if (C->isNullValue()) {
      if (I->hasExternalLinkage()) {
        if (const char *Directive = TAI->getZeroFillDirective()) {
          O << "\t.globl\t" << name << "\n";
          O << Directive << "__DATA__, __common, " << name << ", "
            << Size << ", " << Align << "\n";
          continue;
        }
      }

      if (!I->hasSection() &&
          (I->hasInternalLinkage() || I->hasWeakLinkage() ||
           I->hasLinkOnceLinkage())) {
        if (Size == 0) Size = 1;   // .comm Foo, 0 is undefined, avoid it.
        if (!NoZerosInBSS && TAI->getBSSSection())
          SwitchToDataSection(TAI->getBSSSection(), I);
        else
          SwitchToDataSection(TAI->getDataSection(), I);
        if (TAI->getLCOMMDirective() != NULL) {
          if (I->hasInternalLinkage()) {
            O << TAI->getLCOMMDirective() << name << "," << Size;
            if (Subtarget->isTargetDarwin())
              O << "," << Align;
          } else
            O << TAI->getCOMMDirective()  << name << "," << Size;
        } else {
          if (I->hasInternalLinkage())
            O << "\t.local\t" << name << "\n";
          O << TAI->getCOMMDirective()  << name << "," << Size;
          if (TAI->getCOMMDirectiveTakesAlignment())
            O << "," << (TAI->getAlignmentIsInBytes() ? (1 << Align) : Align);
        }
        O << "\t\t" << TAI->getCommentString() << " " << I->getName() << "\n";
        continue;
      }
    }

    switch (I->getLinkage()) {
    case GlobalValue::LinkOnceLinkage:
    case GlobalValue::WeakLinkage:
      if (Subtarget->isTargetDarwin()) {
        O << "\t.globl " << name << "\n"
          << "\t.weak_definition " << name << "\n";
        SwitchToDataSection("\t.section __DATA,__const_coal,coalesced", I);
      } else {
        std::string SectionName("\t.section\t.llvm.linkonce.d." +
                                name +
                                ",\"aw\",%progbits");
        SwitchToDataSection(SectionName.c_str(), I);
        O << "\t.weak " << name << "\n";
      }
      break;
    case GlobalValue::AppendingLinkage:
      // FIXME: appending linkage variables should go into a section of
      // their name or something.  For now, just emit them as external.
    case GlobalValue::ExternalLinkage:
      O << "\t.globl " << name << "\n";
      // FALL THROUGH
    case GlobalValue::InternalLinkage: {
      if (I->isConstant()) {
        const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
        if (TAI->getCStringSection() && CVA && CVA->isCString()) {
          SwitchToDataSection(TAI->getCStringSection(), I);
          break;
        }
      }
      // FIXME: special handling for ".ctors" & ".dtors" sections
      if (I->hasSection() &&
          (I->getSection() == ".ctors" ||
           I->getSection() == ".dtors")) {
        assert(!Subtarget->isTargetDarwin());
        std::string SectionName = ".section " + I->getSection();
        SectionName += ",\"aw\",%progbits";
        SwitchToDataSection(SectionName.c_str());
      } else {
        if (C->isNullValue() && !NoZerosInBSS && TAI->getBSSSection())
          SwitchToDataSection(TAI->getBSSSection(), I);
        else
          SwitchToDataSection(TAI->getDataSection(), I);
      }

      break;
    }
    default:
      assert(0 && "Unknown linkage type!");
      break;
    }

    EmitAlignment(Align, I);
    O << name << ":\t\t\t\t" << TAI->getCommentString() << " " << I->getName()
      << "\n";
    if (TAI->hasDotTypeDotSizeDirective())
      O << "\t.size " << name << ", " << Size << "\n";
    // If the initializer is a extern weak symbol, remember to emit the weak
    // reference!
    if (const GlobalValue *GV = dyn_cast<GlobalValue>(C))
      if (GV->hasExternalWeakLinkage())
      ExtWeakSymbols.insert(GV);

    EmitGlobalConstant(C);
    O << '\n';
  }

  if (Subtarget->isTargetDarwin()) {
    SwitchToDataSection("");

    // Output stubs for dynamically-linked functions
    unsigned j = 1;
    for (std::set<std::string>::iterator i = FnStubs.begin(), e = FnStubs.end();
         i != e; ++i, ++j) {
      if (TM.getRelocationModel() == Reloc::PIC_)
        SwitchToTextSection(".section __TEXT,__picsymbolstub4,symbol_stubs,"
                            "none,16", 0);
      else
        SwitchToTextSection(".section __TEXT,__symbol_stub4,symbol_stubs,"
                            "none,12", 0);

      EmitAlignment(2);
      O << "\t.code\t32\n";

      O << "L" << *i << "$stub:\n";
      O << "\t.indirect_symbol " << *i << "\n";
      O << "\tldr ip, L" << *i << "$slp\n";
      if (TM.getRelocationModel() == Reloc::PIC_) {
        O << "L" << *i << "$scv:\n";
        O << "\tadd ip, pc, ip\n";
      }
      O << "\tldr pc, [ip, #0]\n";
      O << "L" << *i << "$slp:\n";
      if (TM.getRelocationModel() == Reloc::PIC_)
        O << "\t.long\tL" << *i << "$lazy_ptr-(L" << *i << "$scv+8)\n";
      else
        O << "\t.long\tL" << *i << "$lazy_ptr\n";
      SwitchToDataSection(".lazy_symbol_pointer", 0);
      O << "L" << *i << "$lazy_ptr:\n";
      O << "\t.indirect_symbol " << *i << "\n";
      O << "\t.long\tdyld_stub_binding_helper\n";
    }
    O << "\n";

    // Output non-lazy-pointers for external and common global variables.
    if (GVNonLazyPtrs.begin() != GVNonLazyPtrs.end())
      SwitchToDataSection(".non_lazy_symbol_pointer", 0);
    for (std::set<std::string>::iterator i = GVNonLazyPtrs.begin(),
           e = GVNonLazyPtrs.end(); i != e; ++i) {
      O << "L" << *i << "$non_lazy_ptr:\n";
      O << "\t.indirect_symbol " << *i << "\n";
      O << "\t.long\t0\n";
    }

    // Emit initial debug information.
    DW.EndModule();

    // Funny Darwin hack: This flag tells the linker that no global symbols
    // contain code that falls through to other global symbols (e.g. the obvious
    // implementation of multiple entry points).  If this doesn't occur, the
    // linker can safely perform dead code stripping.  Since LLVM never
    // generates code that does this, it is always safe to set.
    O << "\t.subsections_via_symbols\n";
  }

  AsmPrinter::doFinalization(M);
  return false; // success
}