AsmPrinter.cpp

    for (unsigned j = 0, ee = CPSections[i].CPEs.size(); j != ee; ++j) {
      unsigned CPI = CPSections[i].CPEs[j];
      MachineConstantPoolEntry CPE = CP[CPI];

      // Emit inter-object padding for alignment.
      unsigned AlignMask = CPE.getAlignment() - 1;
      unsigned NewOffset = (Offset + AlignMask) & ~AlignMask;
      OutStreamer.EmitFill(NewOffset - Offset, 0/*fillval*/, 0/*addrspace*/);

      const Type *Ty = CPE.getType();
      Offset = NewOffset + TM.getTargetData()->getTypeAllocSize(Ty);
      OutStreamer.EmitLabel(GetCPISymbol(CPI));

      if (CPE.isMachineConstantPoolEntry())
        EmitMachineConstantPoolValue(CPE.Val.MachineCPVal);
      else
        EmitGlobalConstant(CPE.Val.ConstVal);
    }
  }
}

/// EmitJumpTableInfo - Print assembly representations of the jump tables used
/// by the current function to the current output stream.
///
void AsmPrinter::EmitJumpTableInfo() {
  const MachineJumpTableInfo *MJTI = MF->getJumpTableInfo();
  if (MJTI == 0) return;
  if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_Inline) return;
  const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
  if (JT.empty()) return;

  // Pick the directive to use to print the jump table entries, and switch to
  // the appropriate section.
  const Function *F = MF->getFunction();
  bool JTInDiffSection = false;
  if (// In PIC mode, we need to emit the jump table to the same section as the
      // function body itself, otherwise the label differences won't make sense.
      // FIXME: Need a better predicate for this: what about custom entries?
      MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 ||
      // We should also do if the section name is NULL or function is declared
      // in discardable section
      // FIXME: this isn't the right predicate, should be based on the MCSection
      // for the function.
      F->isWeakForLinker()) {
    OutStreamer.SwitchSection(getObjFileLowering().SectionForGlobal(F,Mang,TM));
  } else {
    // Otherwise, drop it in the readonly section.
    const MCSection *ReadOnlySection =
      getObjFileLowering().getSectionForConstant(SectionKind::getReadOnly());
    OutStreamer.SwitchSection(ReadOnlySection);
    JTInDiffSection = true;
  }

  EmitAlignment(Log2_32(MJTI->getEntryAlignment(*TM.getTargetData())));

  for (unsigned JTI = 0, e = JT.size(); JTI != e; ++JTI) {
    const std::vector<MachineBasicBlock*> &JTBBs = JT[JTI].MBBs;

    // If this jump table was deleted, ignore it.
    if (JTBBs.empty()) continue;

    // For the EK_LabelDifference32 entry, if the target supports .set, emit a
    // .set directive for each unique entry.  This reduces the number of
    // relocations the assembler will generate for the jump table.
    if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 &&
        MAI->hasSetDirective()) {
      SmallPtrSet<const MachineBasicBlock*, 16> EmittedSets;
      const TargetLowering *TLI = TM.getTargetLowering();
      const MCExpr *Base = TLI->getPICJumpTableRelocBaseExpr(MF,JTI,OutContext);
      for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii) {
        const MachineBasicBlock *MBB = JTBBs[ii];
        if (!EmittedSets.insert(MBB)) continue;

        // .set LJTSet, LBB32-base
        const MCExpr *LHS =
          MCSymbolRefExpr::Create(MBB->getSymbol(), OutContext);
        OutStreamer.EmitAssignment(GetJTSetSymbol(JTI, MBB->getNumber()),
                                MCBinaryExpr::CreateSub(LHS, Base, OutContext));
      }
    }

    // On some targets (e.g. Darwin) we want to emit two consecutive labels
    // before each jump table.  The first label is never referenced, but tells
    // the assembler and linker the extents of the jump table object.  The
    // second label is actually referenced by the code.
    if (JTInDiffSection && MAI->getLinkerPrivateGlobalPrefix()[0])
      // FIXME: This doesn't have to have any specific name, just any randomly
      // named and numbered 'l' label would work.  Simplify GetJTISymbol.
      OutStreamer.EmitLabel(GetJTISymbol(JTI, true));

    OutStreamer.EmitLabel(GetJTISymbol(JTI));

    for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii)
      EmitJumpTableEntry(MJTI, JTBBs[ii], JTI);
  }
}

/// EmitJumpTableEntry - Emit a jump table entry for the specified MBB to the
/// current stream.
void AsmPrinter::EmitJumpTableEntry(const MachineJumpTableInfo *MJTI,
                                    const MachineBasicBlock *MBB,
                                    unsigned UID) const {
  assert(MBB && MBB->getNumber() >= 0 && "Invalid basic block");
  const MCExpr *Value = 0;
  switch (MJTI->getEntryKind()) {
  case MachineJumpTableInfo::EK_Inline:
    llvm_unreachable("Cannot emit EK_Inline jump table entry"); break;
  case MachineJumpTableInfo::EK_Custom32:
    Value = TM.getTargetLowering()->LowerCustomJumpTableEntry(MJTI, MBB, UID,
                                                              OutContext);
    break;
  case MachineJumpTableInfo::EK_BlockAddress:
    // EK_BlockAddress - Each entry is a plain address of block, e.g.:
    //     .word LBB123
    Value = MCSymbolRefExpr::Create(MBB->getSymbol(), OutContext);
    break;
  case MachineJumpTableInfo::EK_GPRel32BlockAddress: {
    // EK_GPRel32BlockAddress - Each entry is an address of block, encoded
    // with a relocation as gp-relative, e.g.:
    //     .gprel32 LBB123
    MCSymbol *MBBSym = MBB->getSymbol();
    OutStreamer.EmitGPRel32Value(MCSymbolRefExpr::Create(MBBSym, OutContext));
    return;
  }

  case MachineJumpTableInfo::EK_LabelDifference32: {
    // EK_LabelDifference32 - Each entry is the address of the block minus
    // the address of the jump table.  This is used for PIC jump tables where
    // gprel32 is not supported.  e.g.:
    //      .word LBB123 - LJTI1_2
    // If the .set directive is supported, this is emitted as:
    //      .set L4_5_set_123, LBB123 - LJTI1_2
    //      .word L4_5_set_123

    // If we have emitted set directives for the jump table entries, print
    // them rather than the entries themselves.  If we're emitting PIC, then
    // emit the table entries as differences between two text section labels.
    if (MAI->hasSetDirective()) {
      // If we used .set, reference the .set's symbol.
      Value = MCSymbolRefExpr::Create(GetJTSetSymbol(UID, MBB->getNumber()),
                                      OutContext);
      break;
    }
    // Otherwise, use the difference as the jump table entry.
    Value = MCSymbolRefExpr::Create(MBB->getSymbol(), OutContext);
    const MCExpr *JTI = MCSymbolRefExpr::Create(GetJTISymbol(UID), OutContext);
    Value = MCBinaryExpr::CreateSub(Value, JTI, OutContext);
    break;
  }
  }

  assert(Value && "Unknown entry kind!");

  unsigned EntrySize = MJTI->getEntrySize(*TM.getTargetData());
  OutStreamer.EmitValue(Value, EntrySize, /*addrspace*/0);
}


/// EmitSpecialLLVMGlobal - Check to see if the specified global is a
/// special global used by LLVM.  If so, emit it and return true, otherwise
/// do nothing and return false.
bool AsmPrinter::EmitSpecialLLVMGlobal(const GlobalVariable *GV) {
  if (GV->getName() == "llvm.used") {
    if (MAI->hasNoDeadStrip())    // No need to emit this at all.
      EmitLLVMUsedList(GV->getInitializer());
    return true;
  }

  // Ignore debug and non-emitted data.  This handles llvm.compiler.used.
  if (GV->getSection() == "llvm.metadata" ||
      GV->hasAvailableExternallyLinkage())
    return true;

  if (!GV->hasAppendingLinkage()) return false;

  assert(GV->hasInitializer() && "Not a special LLVM global!");

  const TargetData *TD = TM.getTargetData();
  unsigned Align = Log2_32(TD->getPointerPrefAlignment());
  if (GV->getName() == "llvm.global_ctors") {
    OutStreamer.SwitchSection(getObjFileLowering().getStaticCtorSection());
    EmitAlignment(Align);
    EmitXXStructorList(GV->getInitializer());

    if (TM.getRelocationModel() == Reloc::Static &&
        MAI->hasStaticCtorDtorReferenceInStaticMode()) {
      StringRef Sym(".constructors_used");
      OutStreamer.EmitSymbolAttribute(OutContext.GetOrCreateSymbol(Sym),
                                      MCSA_Reference);
    }
    return true;
  }

  if (GV->getName() == "llvm.global_dtors") {
    OutStreamer.SwitchSection(getObjFileLowering().getStaticDtorSection());
    EmitAlignment(Align);
    EmitXXStructorList(GV->getInitializer());

    if (TM.getRelocationModel() == Reloc::Static &&
        MAI->hasStaticCtorDtorReferenceInStaticMode()) {
      StringRef Sym(".destructors_used");
      OutStreamer.EmitSymbolAttribute(OutContext.GetOrCreateSymbol(Sym),
                                      MCSA_Reference);
    }
    return true;
  }

  return false;
}

/// EmitLLVMUsedList - For targets that define a MAI::UsedDirective, mark each
/// global in the specified llvm.used list for which emitUsedDirectiveFor
/// is true, as being used with this directive.
void AsmPrinter::EmitLLVMUsedList(Constant *List) {
  // Should be an array of 'i8*'.
  ConstantArray *InitList = dyn_cast<ConstantArray>(List);
  if (InitList == 0) return;

  for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
    const GlobalValue *GV =
      dyn_cast<GlobalValue>(InitList->getOperand(i)->stripPointerCasts());
    if (GV && getObjFileLowering().shouldEmitUsedDirectiveFor(GV, Mang))
      OutStreamer.EmitSymbolAttribute(Mang->getSymbol(GV), MCSA_NoDeadStrip);
  }
}

/// EmitXXStructorList - Emit the ctor or dtor list.  This just prints out the
/// function pointers, ignoring the init priority.
void AsmPrinter::EmitXXStructorList(Constant *List) {
  // Should be an array of '{ int, void ()* }' structs.  The first value is the
  // init priority, which we ignore.
  if (!isa<ConstantArray>(List)) return;
  ConstantArray *InitList = cast<ConstantArray>(List);
  for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i)
    if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){
      if (CS->getNumOperands() != 2) return;  // Not array of 2-element structs.

      if (CS->getOperand(1)->isNullValue())
        return;  // Found a null terminator, exit printing.
      // Emit the function pointer.
      EmitGlobalConstant(CS->getOperand(1));
    }
}

//===--------------------------------------------------------------------===//
// Emission and print routines
//

/// EmitInt8 - Emit a byte directive and value.
///
void AsmPrinter::EmitInt8(int Value) const {
  OutStreamer.EmitIntValue(Value, 1, 0/*addrspace*/);
}

/// EmitInt16 - Emit a short directive and value.
///
void AsmPrinter::EmitInt16(int Value) const {
  OutStreamer.EmitIntValue(Value, 2, 0/*addrspace*/);
}

/// EmitInt32 - Emit a long directive and value.
///
void AsmPrinter::EmitInt32(int Value) const {
  OutStreamer.EmitIntValue(Value, 4, 0/*addrspace*/);
}

/// EmitLabelDifference - Emit something like ".long Hi-Lo" where the size
/// in bytes of the directive is specified by Size and Hi/Lo specify the
/// labels.  This implicitly uses .set if it is available.
void AsmPrinter::EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
                                     unsigned Size) const {
  // Get the Hi-Lo expression.
  const MCExpr *Diff =
    MCBinaryExpr::CreateSub(MCSymbolRefExpr::Create(Hi, OutContext),
                            MCSymbolRefExpr::Create(Lo, OutContext),
                            OutContext);

  if (!MAI->hasSetDirective()) {
    OutStreamer.EmitValue(Diff, Size, 0/*AddrSpace*/);
    return;
  }

  // Otherwise, emit with .set (aka assignment).
  MCSymbol *SetLabel = GetTempSymbol("set", SetCounter++);
  OutStreamer.EmitAssignment(SetLabel, Diff);
  OutStreamer.EmitSymbolValue(SetLabel, Size, 0/*AddrSpace*/);
}

/// EmitLabelOffsetDifference - Emit something like ".long Hi+Offset-Lo"
/// where the size in bytes of the directive is specified by Size and Hi/Lo
/// specify the labels.  This implicitly uses .set if it is available.
void AsmPrinter::EmitLabelOffsetDifference(const MCSymbol *Hi, uint64_t Offset,
                                           const MCSymbol *Lo, unsigned Size)
  const {

  // Emit Hi+Offset - Lo
  // Get the Hi+Offset expression.
  const MCExpr *Plus =
    MCBinaryExpr::CreateAdd(MCSymbolRefExpr::Create(Hi, OutContext),
                            MCConstantExpr::Create(Offset, OutContext),
                            OutContext);

  // Get the Hi+Offset-Lo expression.
  const MCExpr *Diff =
    MCBinaryExpr::CreateSub(Plus,
                            MCSymbolRefExpr::Create(Lo, OutContext),
                            OutContext);

  if (!MAI->hasSetDirective())
    OutStreamer.EmitValue(Diff, 4, 0/*AddrSpace*/);
  else {
    // Otherwise, emit with .set (aka assignment).
    MCSymbol *SetLabel = GetTempSymbol("set", SetCounter++);
    OutStreamer.EmitAssignment(SetLabel, Diff);
    OutStreamer.EmitSymbolValue(SetLabel, 4, 0/*AddrSpace*/);
  }
}

/// EmitLabelPlusOffset - Emit something like ".long Label+Offset"
/// where the size in bytes of the directive is specified by Size and Label
/// specifies the label.  This implicitly uses .set if it is available.
void AsmPrinter::EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
                                      unsigned Size)
  const {

  // Emit Label+Offset
  const MCExpr *Plus =
    MCBinaryExpr::CreateAdd(MCSymbolRefExpr::Create(Label, OutContext),
                            MCConstantExpr::Create(Offset, OutContext),
                            OutContext);

  OutStreamer.EmitValue(Plus, 4, 0/*AddrSpace*/);
}


//===----------------------------------------------------------------------===//

// EmitAlignment - Emit an alignment directive to the specified power of
// two boundary.  For example, if you pass in 3 here, you will get an 8
// byte alignment.  If a global value is specified, and if that global has
// an explicit alignment requested, it will override the alignment request
// if required for correctness.
//
void AsmPrinter::EmitAlignment(unsigned NumBits, const GlobalValue *GV) const {
  if (GV) NumBits = getGVAlignmentLog2(GV, *TM.getTargetData(), NumBits);

  if (NumBits == 0) return;   // 1-byte aligned: no need to emit alignment.

  if (getCurrentSection()->getKind().isText())
    OutStreamer.EmitCodeAlignment(1 << NumBits);
  else
    OutStreamer.EmitValueToAlignment(1 << NumBits, 0, 1, 0);
}

//===----------------------------------------------------------------------===//
// Constant emission.
//===----------------------------------------------------------------------===//

/// LowerConstant - Lower the specified LLVM Constant to an MCExpr.
///
static const MCExpr *LowerConstant(const Constant *CV, AsmPrinter &AP) {
  MCContext &Ctx = AP.OutContext;

  if (CV->isNullValue() || isa<UndefValue>(CV))
    return MCConstantExpr::Create(0, Ctx);

  if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV))
    return MCConstantExpr::Create(CI->getZExtValue(), Ctx);

  if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV))
    return MCSymbolRefExpr::Create(AP.Mang->getSymbol(GV), Ctx);

  if (const BlockAddress *BA = dyn_cast<BlockAddress>(CV))
    return MCSymbolRefExpr::Create(AP.GetBlockAddressSymbol(BA), Ctx);

  const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV);
  if (CE == 0) {
    llvm_unreachable("Unknown constant value to lower!");
    return MCConstantExpr::Create(0, Ctx);
  }

  switch (CE->getOpcode()) {
  default:
    // If the code isn't optimized, there may be outstanding folding
    // opportunities. Attempt to fold the expression using TargetData as a
    // last resort before giving up.
    if (Constant *C =
          ConstantFoldConstantExpression(CE, AP.TM.getTargetData()))
      if (C != CE)
        return LowerConstant(C, AP);

    // Otherwise report the problem to the user.
    {
      std::string S;
      raw_string_ostream OS(S);
      OS << "Unsupported expression in static initializer: ";
      WriteAsOperand(OS, CE, /*PrintType=*/false,
                     !AP.MF ? 0 : AP.MF->getFunction()->getParent());
      report_fatal_error(OS.str());
    }
    return MCConstantExpr::Create(0, Ctx);
  case Instruction::GetElementPtr: {
    const TargetData &TD = *AP.TM.getTargetData();
    // Generate a symbolic expression for the byte address
    const Constant *PtrVal = CE->getOperand(0);
    SmallVector<Value*, 8> IdxVec(CE->op_begin()+1, CE->op_end());
    int64_t Offset = TD.getIndexedOffset(PtrVal->getType(), &IdxVec[0],
                                         IdxVec.size());

    const MCExpr *Base = LowerConstant(CE->getOperand(0), AP);
    if (Offset == 0)
      return Base;

    // Truncate/sext the offset to the pointer size.
    if (TD.getPointerSizeInBits() != 64) {
      int SExtAmount = 64-TD.getPointerSizeInBits();
      Offset = (Offset << SExtAmount) >> SExtAmount;
    }

    return MCBinaryExpr::CreateAdd(Base, MCConstantExpr::Create(Offset, Ctx),
                                   Ctx);
  }

  case Instruction::Trunc:
    // We emit the value and depend on the assembler to truncate the generated
    // expression properly.  This is important for differences between
    // blockaddress labels.  Since the two labels are in the same function, it
    // is reasonable to treat their delta as a 32-bit value.
    // FALL THROUGH.
  case Instruction::BitCast:
    return LowerConstant(CE->getOperand(0), AP);

  case Instruction::IntToPtr: {
    const TargetData &TD = *AP.TM.getTargetData();
    // Handle casts to pointers by changing them into casts to the appropriate
    // integer type.  This promotes constant folding and simplifies this code.
    Constant *Op = CE->getOperand(0);
    Op = ConstantExpr::getIntegerCast(Op, TD.getIntPtrType(CV->getContext()),
                                      false/*ZExt*/);
    return LowerConstant(Op, AP);
  }

  case Instruction::PtrToInt: {
    const TargetData &TD = *AP.TM.getTargetData();
    // Support only foldable casts to/from pointers that can be eliminated by
    // changing the pointer to the appropriately sized integer type.
    Constant *Op = CE->getOperand(0);
    const Type *Ty = CE->getType();

    const MCExpr *OpExpr = LowerConstant(Op, AP);

    // We can emit the pointer value into this slot if the slot is an
    // integer slot equal to the size of the pointer.
    if (TD.getTypeAllocSize(Ty) == TD.getTypeAllocSize(Op->getType()))
      return OpExpr;

    // Otherwise the pointer is smaller than the resultant integer, mask off
    // the high bits so we are sure to get a proper truncation if the input is
    // a constant expr.
    unsigned InBits = TD.getTypeAllocSizeInBits(Op->getType());
    const MCExpr *MaskExpr = MCConstantExpr::Create(~0ULL >> (64-InBits), Ctx);
    return MCBinaryExpr::CreateAnd(OpExpr, MaskExpr, Ctx);
  }

  // The MC library also has a right-shift operator, but it isn't consistently
  // signed or unsigned between different targets.
  case Instruction::Add:
  case Instruction::Sub:
  case Instruction::Mul:
  case Instruction::SDiv:
  case Instruction::SRem:
  case Instruction::Shl:
  case Instruction::And:
  case Instruction::Or:
  case Instruction::Xor: {
    const MCExpr *LHS = LowerConstant(CE->getOperand(0), AP);
    const MCExpr *RHS = LowerConstant(CE->getOperand(1), AP);
    switch (CE->getOpcode()) {
    default: llvm_unreachable("Unknown binary operator constant cast expr");
    case Instruction::Add: return MCBinaryExpr::CreateAdd(LHS, RHS, Ctx);
    case Instruction::Sub: return MCBinaryExpr::CreateSub(LHS, RHS, Ctx);
    case Instruction::Mul: return MCBinaryExpr::CreateMul(LHS, RHS, Ctx);
    case Instruction::SDiv: return MCBinaryExpr::CreateDiv(LHS, RHS, Ctx);
    case Instruction::SRem: return MCBinaryExpr::CreateMod(LHS, RHS, Ctx);
    case Instruction::Shl: return MCBinaryExpr::CreateShl(LHS, RHS, Ctx);
    case Instruction::And: return MCBinaryExpr::CreateAnd(LHS, RHS, Ctx);
    case Instruction::Or:  return MCBinaryExpr::CreateOr (LHS, RHS, Ctx);
    case Instruction::Xor: return MCBinaryExpr::CreateXor(LHS, RHS, Ctx);
    }
  }
  }
}

static void EmitGlobalConstantImpl(const Constant *C, unsigned AddrSpace,
                                   AsmPrinter &AP);

static void EmitGlobalConstantArray(const ConstantArray *CA, unsigned AddrSpace,
                                    AsmPrinter &AP) {
  if (AddrSpace != 0 || !CA->isString()) {
    // Not a string.  Print the values in successive locations
    for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
      EmitGlobalConstantImpl(CA->getOperand(i), AddrSpace, AP);
    return;
  }

  // Otherwise, it can be emitted as .ascii.
  SmallVector<char, 128> TmpVec;
  TmpVec.reserve(CA->getNumOperands());
  for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i)
    TmpVec.push_back(cast<ConstantInt>(CA->getOperand(i))->getZExtValue());

  AP.OutStreamer.EmitBytes(StringRef(TmpVec.data(), TmpVec.size()), AddrSpace);
}

static void EmitGlobalConstantVector(const ConstantVector *CV,
                                     unsigned AddrSpace, AsmPrinter &AP) {
  for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
    EmitGlobalConstantImpl(CV->getOperand(i), AddrSpace, AP);
}

static void EmitGlobalConstantStruct(const ConstantStruct *CS,
                                     unsigned AddrSpace, AsmPrinter &AP) {
  // Print the fields in successive locations. Pad to align if needed!
  const TargetData *TD = AP.TM.getTargetData();
  unsigned Size = TD->getTypeAllocSize(CS->getType());
  const StructLayout *Layout = TD->getStructLayout(CS->getType());
  uint64_t SizeSoFar = 0;
  for (unsigned i = 0, e = CS->getNumOperands(); i != e; ++i) {
    const Constant *Field = CS->getOperand(i);

    // Check if padding is needed and insert one or more 0s.
    uint64_t FieldSize = TD->getTypeAllocSize(Field->getType());
    uint64_t PadSize = ((i == e-1 ? Size : Layout->getElementOffset(i+1))
                        - Layout->getElementOffset(i)) - FieldSize;
    SizeSoFar += FieldSize + PadSize;

    // Now print the actual field value.
    EmitGlobalConstantImpl(Field, AddrSpace, AP);

    // Insert padding - this may include padding to increase the size of the
    // current field up to the ABI size (if the struct is not packed) as well
    // as padding to ensure that the next field starts at the right offset.
    AP.OutStreamer.EmitZeros(PadSize, AddrSpace);
  }
  assert(SizeSoFar == Layout->getSizeInBytes() &&
         "Layout of constant struct may be incorrect!");
}

static void EmitGlobalConstantFP(const ConstantFP *CFP, unsigned AddrSpace,
                                 AsmPrinter &AP) {
  // FP Constants are printed as integer constants to avoid losing
  // precision.
  if (CFP->getType()->isDoubleTy()) {
    if (AP.isVerbose()) {
      double Val = CFP->getValueAPF().convertToDouble();
      AP.OutStreamer.GetCommentOS() << "double " << Val << '\n';
    }

    uint64_t Val = CFP->getValueAPF().bitcastToAPInt().getZExtValue();
    AP.OutStreamer.EmitIntValue(Val, 8, AddrSpace);
    return;
  }

  if (CFP->getType()->isFloatTy()) {
    if (AP.isVerbose()) {
      float Val = CFP->getValueAPF().convertToFloat();
      AP.OutStreamer.GetCommentOS() << "float " << Val << '\n';
    }
    uint64_t Val = CFP->getValueAPF().bitcastToAPInt().getZExtValue();
    AP.OutStreamer.EmitIntValue(Val, 4, AddrSpace);
    return;
  }

  if (CFP->getType()->isX86_FP80Ty()) {
    // all long double variants are printed as hex
    // API needed to prevent premature destruction
    APInt API = CFP->getValueAPF().bitcastToAPInt();
    const uint64_t *p = API.getRawData();
    if (AP.isVerbose()) {
      // Convert to double so we can print the approximate val as a comment.
      APFloat DoubleVal = CFP->getValueAPF();
      bool ignored;
      DoubleVal.convert(APFloat::IEEEdouble, APFloat::rmNearestTiesToEven,
                        &ignored);
      AP.OutStreamer.GetCommentOS() << "x86_fp80 ~= "
        << DoubleVal.convertToDouble() << '\n';
    }

    if (AP.TM.getTargetData()->isBigEndian()) {
      AP.OutStreamer.EmitIntValue(p[1], 2, AddrSpace);
      AP.OutStreamer.EmitIntValue(p[0], 8, AddrSpace);
    } else {
      AP.OutStreamer.EmitIntValue(p[0], 8, AddrSpace);
      AP.OutStreamer.EmitIntValue(p[1], 2, AddrSpace);
    }

    // Emit the tail padding for the long double.
    const TargetData &TD = *AP.TM.getTargetData();
    AP.OutStreamer.EmitZeros(TD.getTypeAllocSize(CFP->getType()) -
                             TD.getTypeStoreSize(CFP->getType()), AddrSpace);
    return;
  }

  assert(CFP->getType()->isPPC_FP128Ty() &&
         "Floating point constant type not handled");
  // All long double variants are printed as hex
  // API needed to prevent premature destruction.
  APInt API = CFP->getValueAPF().bitcastToAPInt();
  const uint64_t *p = API.getRawData();
  if (AP.TM.getTargetData()->isBigEndian()) {
    AP.OutStreamer.EmitIntValue(p[0], 8, AddrSpace);
    AP.OutStreamer.EmitIntValue(p[1], 8, AddrSpace);
  } else {
    AP.OutStreamer.EmitIntValue(p[1], 8, AddrSpace);
    AP.OutStreamer.EmitIntValue(p[0], 8, AddrSpace);
  }
}

static void EmitGlobalConstantLargeInt(const ConstantInt *CI,
                                       unsigned AddrSpace, AsmPrinter &AP) {
  const TargetData *TD = AP.TM.getTargetData();
  unsigned BitWidth = CI->getBitWidth();
  assert((BitWidth & 63) == 0 && "only support multiples of 64-bits");

  // We don't expect assemblers to support integer data directives
  // for more than 64 bits, so we emit the data in at most 64-bit
  // quantities at a time.
  const uint64_t *RawData = CI->getValue().getRawData();
  for (unsigned i = 0, e = BitWidth / 64; i != e; ++i) {
    uint64_t Val = TD->isBigEndian() ? RawData[e - i - 1] : RawData[i];
    AP.OutStreamer.EmitIntValue(Val, 8, AddrSpace);
  }
}

static void EmitGlobalConstantImpl(const Constant *CV, unsigned AddrSpace,
                                   AsmPrinter &AP) {
  if (isa<ConstantAggregateZero>(CV) || isa<UndefValue>(CV)) {
    uint64_t Size = AP.TM.getTargetData()->getTypeAllocSize(CV->getType());
    return AP.OutStreamer.EmitZeros(Size, AddrSpace);
  }

  if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
    unsigned Size = AP.TM.getTargetData()->getTypeAllocSize(CV->getType());
    switch (Size) {
    case 1:
    case 2:
    case 4:
    case 8:
      if (AP.isVerbose())
        AP.OutStreamer.GetCommentOS() << format("0x%llx\n", CI->getZExtValue());
      AP.OutStreamer.EmitIntValue(CI->getZExtValue(), Size, AddrSpace);
      return;
    default:
      EmitGlobalConstantLargeInt(CI, AddrSpace, AP);
      return;
    }
  }

  if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV))
    return EmitGlobalConstantArray(CVA, AddrSpace, AP);

  if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV))
    return EmitGlobalConstantStruct(CVS, AddrSpace, AP);

  if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV))
    return EmitGlobalConstantFP(CFP, AddrSpace, AP);

  if (isa<ConstantPointerNull>(CV)) {
    unsigned Size = AP.TM.getTargetData()->getTypeAllocSize(CV->getType());
    AP.OutStreamer.EmitIntValue(0, Size, AddrSpace);
    return;
  }

  if (const ConstantVector *V = dyn_cast<ConstantVector>(CV))
    return EmitGlobalConstantVector(V, AddrSpace, AP);

  // Otherwise, it must be a ConstantExpr.  Lower it to an MCExpr, then emit it
  // thread the streamer with EmitValue.
  AP.OutStreamer.EmitValue(LowerConstant(CV, AP),
                         AP.TM.getTargetData()->getTypeAllocSize(CV->getType()),
                           AddrSpace);
}

/// EmitGlobalConstant - Print a general LLVM constant to the .s file.
void AsmPrinter::EmitGlobalConstant(const Constant *CV, unsigned AddrSpace) {
  uint64_t Size = TM.getTargetData()->getTypeAllocSize(CV->getType());
  if (Size)
    EmitGlobalConstantImpl(CV, AddrSpace, *this);
  else if (MAI->hasSubsectionsViaSymbols()) {
    // If the global has zero size, emit a single byte so that two labels don't
    // look like they are at the same location.
    OutStreamer.EmitIntValue(0, 1, AddrSpace);
  }
}

void AsmPrinter::EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV) {
  // Target doesn't support this yet!
  llvm_unreachable("Target does not support EmitMachineConstantPoolValue");
}

void AsmPrinter::printOffset(int64_t Offset, raw_ostream &OS) const {
  if (Offset > 0)
    OS << '+' << Offset;
  else if (Offset < 0)
    OS << Offset;
}

//===----------------------------------------------------------------------===//
// Symbol Lowering Routines.
//===----------------------------------------------------------------------===//

/// GetTempSymbol - Return the MCSymbol corresponding to the assembler
/// temporary label with the specified stem and unique ID.
MCSymbol *AsmPrinter::GetTempSymbol(StringRef Name, unsigned ID) const {
  return OutContext.GetOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix()) +
                                      Name + Twine(ID));
}

/// GetTempSymbol - Return an assembler temporary label with the specified
/// stem.
MCSymbol *AsmPrinter::GetTempSymbol(StringRef Name) const {
  return OutContext.GetOrCreateSymbol(Twine(MAI->getPrivateGlobalPrefix())+
                                      Name);
}


MCSymbol *AsmPrinter::GetBlockAddressSymbol(const BlockAddress *BA) const {
  return MMI->getAddrLabelSymbol(BA->getBasicBlock());
}

MCSymbol *AsmPrinter::GetBlockAddressSymbol(const BasicBlock *BB) const {
  return MMI->getAddrLabelSymbol(BB);
}

/// GetCPISymbol - Return the symbol for the specified constant pool entry.
MCSymbol *AsmPrinter::GetCPISymbol(unsigned CPID) const {
  return OutContext.GetOrCreateSymbol
    (Twine(MAI->getPrivateGlobalPrefix()) + "CPI" + Twine(getFunctionNumber())
     + "_" + Twine(CPID));
}

/// GetJTISymbol - Return the symbol for the specified jump table entry.
MCSymbol *AsmPrinter::GetJTISymbol(unsigned JTID, bool isLinkerPrivate) const {
  return MF->getJTISymbol(JTID, OutContext, isLinkerPrivate);
}

/// GetJTSetSymbol - Return the symbol for the specified jump table .set
/// FIXME: privatize to AsmPrinter.
MCSymbol *AsmPrinter::GetJTSetSymbol(unsigned UID, unsigned MBBID) const {
  return OutContext.GetOrCreateSymbol
  (Twine(MAI->getPrivateGlobalPrefix()) + Twine(getFunctionNumber()) + "_" +
   Twine(UID) + "_set_" + Twine(MBBID));
}

/// GetSymbolWithGlobalValueBase - Return the MCSymbol for a symbol with
/// global value name as its base, with the specified suffix, and where the
/// symbol is forced to have private linkage if ForcePrivate is true.
MCSymbol *AsmPrinter::GetSymbolWithGlobalValueBase(const GlobalValue *GV,
                                                   StringRef Suffix,
                                                   bool ForcePrivate) const {
  SmallString<60> NameStr;
  Mang->getNameWithPrefix(NameStr, GV, ForcePrivate);
  NameStr.append(Suffix.begin(), Suffix.end());
  return OutContext.GetOrCreateSymbol(NameStr.str());
}

/// GetExternalSymbolSymbol - Return the MCSymbol for the specified
/// ExternalSymbol.
MCSymbol *AsmPrinter::GetExternalSymbolSymbol(StringRef Sym) const {
  SmallString<60> NameStr;
  Mang->getNameWithPrefix(NameStr, Sym);
  return OutContext.GetOrCreateSymbol(NameStr.str());
}



/// PrintParentLoopComment - Print comments about parent loops of this one.
static void PrintParentLoopComment(raw_ostream &OS, const MachineLoop *Loop,
                                   unsigned FunctionNumber) {
  if (Loop == 0) return;
  PrintParentLoopComment(OS, Loop->getParentLoop(), FunctionNumber);
  OS.indent(Loop->getLoopDepth()*2)
    << "Parent Loop BB" << FunctionNumber << "_"
    << Loop->getHeader()->getNumber()
    << " Depth=" << Loop->getLoopDepth() << '\n';
}


/// PrintChildLoopComment - Print comments about child loops within
/// the loop for this basic block, with nesting.
static void PrintChildLoopComment(raw_ostream &OS, const MachineLoop *Loop,
                                  unsigned FunctionNumber) {
  // Add child loop information
  for (MachineLoop::iterator CL = Loop->begin(), E = Loop->end();CL != E; ++CL){
    OS.indent((*CL)->getLoopDepth()*2)
      << "Child Loop BB" << FunctionNumber << "_"
      << (*CL)->getHeader()->getNumber() << " Depth " << (*CL)->getLoopDepth()
      << '\n';
    PrintChildLoopComment(OS, *CL, FunctionNumber);
  }
}

/// EmitBasicBlockLoopComments - Pretty-print comments for basic blocks.
static void EmitBasicBlockLoopComments(const MachineBasicBlock &MBB,
                                       const MachineLoopInfo *LI,
                                       const AsmPrinter &AP) {
  // Add loop depth information
  const MachineLoop *Loop = LI->getLoopFor(&MBB);
  if (Loop == 0) return;

  MachineBasicBlock *Header = Loop->getHeader();
  assert(Header && "No header for loop");

  // If this block is not a loop header, just print out what is the loop header
  // and return.
  if (Header != &MBB) {
    AP.OutStreamer.AddComment("  in Loop: Header=BB" +
                              Twine(AP.getFunctionNumber())+"_" +
                              Twine(Loop->getHeader()->getNumber())+
                              " Depth="+Twine(Loop->getLoopDepth()));
    return;
  }

  // Otherwise, it is a loop header.  Print out information about child and
  // parent loops.
  raw_ostream &OS = AP.OutStreamer.GetCommentOS();

  PrintParentLoopComment(OS, Loop->getParentLoop(), AP.getFunctionNumber());

  OS << "=>";
  OS.indent(Loop->getLoopDepth()*2-2);

  OS << "This ";
  if (Loop->empty())
    OS << "Inner ";
  OS << "Loop Header: Depth=" + Twine(Loop->getLoopDepth()) << '\n';

  PrintChildLoopComment(OS, Loop, AP.getFunctionNumber());
}


/// EmitBasicBlockStart - This method prints the label for the specified
/// MachineBasicBlock, an alignment (if present) and a comment describing
/// it if appropriate.
void AsmPrinter::EmitBasicBlockStart(const MachineBasicBlock *MBB) const {
  // Emit an alignment directive for this block, if needed.
  if (unsigned Align = MBB->getAlignment())
    EmitAlignment(Log2_32(Align));

  // If the block has its address taken, emit any labels that were used to
  // reference the block.  It is possible that there is more than one label
  // here, because multiple LLVM BB's may have been RAUW'd to this block after
  // the references were generated.
  if (MBB->hasAddressTaken()) {
    const BasicBlock *BB = MBB->getBasicBlock();
    if (isVerbose())
      OutStreamer.AddComment("Block address taken");

    std::vector<MCSymbol*> Syms = MMI->getAddrLabelSymbolToEmit(BB);

    for (unsigned i = 0, e = Syms.size(); i != e; ++i)
      OutStreamer.EmitLabel(Syms[i]);
  }

  // Print the main label for the block.
  if (MBB->pred_empty() || isBlockOnlyReachableByFallthrough(MBB)) {
    if (isVerbose() && OutStreamer.hasRawTextSupport()) {
      if (const BasicBlock *BB = MBB->getBasicBlock())
        if (BB->hasName())
          OutStreamer.AddComment("%" + BB->getName());

      EmitBasicBlockLoopComments(*MBB, LI, *this);

      // NOTE: Want this comment at start of line, don't emit with AddComment.
      OutStreamer.EmitRawText(Twine(MAI->getCommentString()) + " BB#" +
                              Twine(MBB->getNumber()) + ":");
    }
  } else {
    if (isVerbose()) {
      if (const BasicBlock *BB = MBB->getBasicBlock())
        if (BB->hasName())
          OutStreamer.AddComment("%" + BB->getName());
      EmitBasicBlockLoopComments(*MBB, LI, *this);
    }

    OutStreamer.EmitLabel(MBB->getSymbol());
  }
}

void AsmPrinter::EmitVisibility(MCSymbol *Sym, unsigned Visibility,
                                bool IsDefinition) const {
  MCSymbolAttr Attr = MCSA_Invalid;

  switch (Visibility) {
  default: break;
  case GlobalValue::HiddenVisibility:
    if (IsDefinition)
      Attr = MAI->getHiddenVisibilityAttr();
    else
      Attr = MAI->getHiddenDeclarationVisibilityAttr();
    break;
  case GlobalValue::ProtectedVisibility:
    Attr = MAI->getProtectedVisibilityAttr();
    break;
  }

  if (Attr != MCSA_Invalid)
    OutStreamer.EmitSymbolAttribute(Sym, Attr);
}

/// isBlockOnlyReachableByFallthough - Return true if the basic block has
/// exactly one predecessor and the control transfer mechanism between
/// the predecessor and this block is a fall-through.
bool AsmPrinter::
isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const {
  // If this is a landing pad, it isn't a fall through.  If it has no preds,
  // then nothing falls through to it.
  if (MBB->isLandingPad() || MBB->pred_empty())
    return false;

  // If there isn't exactly one predecessor, it can't be a fall through.
  MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(), PI2 = PI;
  ++PI2;
  if (PI2 != MBB->pred_end())
    return false;

  // The predecessor has to be immediately before this block.
  const MachineBasicBlock *Pred = *PI;

  if (!Pred->isLayoutSuccessor(MBB))
    return false;

  // If the block is completely empty, then it definitely does fall through.
  if (Pred->empty())
    return true;

  // Otherwise, check the last instruction.
  const MachineInstr &LastInst = Pred->back();
  return !LastInst.getDesc().isBarrier();
}



GCMetadataPrinter *AsmPrinter::GetOrCreateGCPrinter(GCStrategy *S) {
  if (!S->usesMetadata())
    return 0;

  gcp_map_type &GCMap = getGCMap(GCMetadataPrinters);
  gcp_map_type::iterator GCPI = GCMap.find(S);
  if (GCPI != GCMap.end())
    return GCPI->second;

  const char *Name = S->getName().c_str();

  for (GCMetadataPrinterRegistry::iterator
         I = GCMetadataPrinterRegistry::begin(),
         E = GCMetadataPrinterRegistry::end(); I != E; ++I)
    if (strcmp(Name, I->getName()) == 0) {
      GCMetadataPrinter *GMP = I->instantiate();
      GMP->S = S;
      GCMap.insert(std::make_pair(S, GMP));
      return GMP;
    }

  report_fatal_error("no GCMetadataPrinter registered for GC: " + Twine(Name));
  return 0;
}