llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp

//===-- PPCAsmPrinter.cpp - Print machine instrs to PowerPC assembly ------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains a printer that converts from our internal representation
// of machine-dependent LLVM code to PowerPC assembly language. This printer is
// the output mechanism used by `llc'.
//
// Documentation at http://developer.apple.com/documentation/DeveloperTools/
// Reference/Assembler/ASMIntroduction/chapter_1_section_1.html
//
//===----------------------------------------------------------------------===//

#include "InstPrinter/PPCInstPrinter.h"
#include "MCTargetDesc/PPCMCExpr.h"
#include "MCTargetDesc/PPCMCTargetDesc.h"
#include "MCTargetDesc/PPCPredicates.h"
#include "PPC.h"
#include "PPCInstrInfo.h"
#include "PPCMachineFunctionInfo.h"
#include "PPCSubtarget.h"
#include "PPCTargetMachine.h"
#include "PPCTargetStreamer.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Triple.h"
#include "llvm/ADT/Twine.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/BinaryFormat/MachO.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineModuleInfoImpls.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/StackMaps.h"
#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstBuilder.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCSymbolELF.h"
#include "llvm/MC/SectionKind.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <memory>
#include <new>

using namespace llvm;

#define DEBUG_TYPE "asmprinter"

namespace {

class PPCAsmPrinter : public AsmPrinter {
protected:
  MapVector<MCSymbol *, MCSymbol *> TOC;
  const PPCSubtarget *Subtarget;
  StackMaps SM;

public:
  explicit PPCAsmPrinter(TargetMachine &TM,
                         std::unique_ptr<MCStreamer> Streamer)
      : AsmPrinter(TM, std::move(Streamer)), SM(*this) {}

  StringRef getPassName() const override { return "PowerPC Assembly Printer"; }

  MCSymbol *lookUpOrCreateTOCEntry(MCSymbol *Sym);

  bool doInitialization(Module &M) override {
    if (!TOC.empty())
      TOC.clear();
    return AsmPrinter::doInitialization(M);
  }

    void EmitInstruction(const MachineInstr *MI) override;

    void printOperand(const MachineInstr *MI, unsigned OpNo, raw_ostream &O);

    bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                         unsigned AsmVariant, const char *ExtraCode,
                         raw_ostream &O) override;
    bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
                               unsigned AsmVariant, const char *ExtraCode,
                               raw_ostream &O) override;

    void EmitEndOfAsmFile(Module &M) override;

    void LowerSTACKMAP(StackMaps &SM, const MachineInstr &MI);
    void LowerPATCHPOINT(StackMaps &SM, const MachineInstr &MI);
    void EmitTlsCall(const MachineInstr *MI, MCSymbolRefExpr::VariantKind VK);
    bool runOnMachineFunction(MachineFunction &MF) override {
      Subtarget = &MF.getSubtarget<PPCSubtarget>();
      bool Changed = AsmPrinter::runOnMachineFunction(MF);
      emitXRayTable();
      return Changed;
    }
  };

  /// PPCLinuxAsmPrinter - PowerPC assembly printer, customized for Linux
  class PPCLinuxAsmPrinter : public PPCAsmPrinter {
  public:
    explicit PPCLinuxAsmPrinter(TargetMachine &TM,
                                std::unique_ptr<MCStreamer> Streamer)
        : PPCAsmPrinter(TM, std::move(Streamer)) {}

    StringRef getPassName() const override {
      return "Linux PPC Assembly Printer";
    }

    bool doFinalization(Module &M) override;
    void EmitStartOfAsmFile(Module &M) override;

    void EmitFunctionEntryLabel() override;

    void EmitFunctionBodyStart() override;
    void EmitFunctionBodyEnd() override;
    void EmitInstruction(const MachineInstr *MI) override;
  };

  /// PPCDarwinAsmPrinter - PowerPC assembly printer, customized for Darwin/Mac
  /// OS X
  class PPCDarwinAsmPrinter : public PPCAsmPrinter {
  public:
    explicit PPCDarwinAsmPrinter(TargetMachine &TM,
                                 std::unique_ptr<MCStreamer> Streamer)
        : PPCAsmPrinter(TM, std::move(Streamer)) {}

    StringRef getPassName() const override {
      return "Darwin PPC Assembly Printer";
    }

    bool doFinalization(Module &M) override;
    void EmitStartOfAsmFile(Module &M) override;
  };

} // end anonymous namespace

void PPCAsmPrinter::printOperand(const MachineInstr *MI, unsigned OpNo,
                                 raw_ostream &O) {
  const DataLayout &DL = getDataLayout();
  const MachineOperand &MO = MI->getOperand(OpNo);

  switch (MO.getType()) {
  case MachineOperand::MO_Register: {
    unsigned Reg = PPCInstrInfo::getRegNumForOperand(MI->getDesc(),
                                                     MO.getReg(), OpNo);

    const char *RegName = PPCInstPrinter::getRegisterName(Reg);

    // Linux assembler (Others?) does not take register mnemonics.
    // FIXME - What about special registers used in mfspr/mtspr?
    if (!Subtarget->isDarwin())
      RegName = PPCRegisterInfo::stripRegisterPrefix(RegName);
    O << RegName;
    return;
  }
  case MachineOperand::MO_Immediate:
    O << MO.getImm();
    return;

  case MachineOperand::MO_MachineBasicBlock:
    MO.getMBB()->getSymbol()->print(O, MAI);
    return;
  case MachineOperand::MO_ConstantPoolIndex:
    O << DL.getPrivateGlobalPrefix() << "CPI" << getFunctionNumber() << '_'
      << MO.getIndex();
    return;
  case MachineOperand::MO_BlockAddress:
    GetBlockAddressSymbol(MO.getBlockAddress())->print(O, MAI);
    return;
  case MachineOperand::MO_GlobalAddress: {
    // Computing the address of a global symbol, not calling it.
    const GlobalValue *GV = MO.getGlobal();
    MCSymbol *SymToPrint;

    // External or weakly linked global variables need non-lazily-resolved stubs
    if (Subtarget->hasLazyResolverStub(GV)) {
      SymToPrint = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
      MachineModuleInfoImpl::StubValueTy &StubSym =
          MMI->getObjFileInfo<MachineModuleInfoMachO>().getGVStubEntry(
              SymToPrint);
      if (!StubSym.getPointer())
        StubSym = MachineModuleInfoImpl::StubValueTy(getSymbol(GV),
                                                     !GV->hasInternalLinkage());
    } else {
      SymToPrint = getSymbol(GV);
    }

    SymToPrint->print(O, MAI);

    printOffset(MO.getOffset(), O);
    return;
  }

  default:
    O << "<unknown operand type: " << (unsigned)MO.getType() << ">";
    return;
  }
}

/// PrintAsmOperand - Print out an operand for an inline asm expression.
///
bool PPCAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                                    unsigned AsmVariant,
                                    const char *ExtraCode, raw_ostream &O) {
  // 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:
      // See if this is a generic print operand
      return AsmPrinter::PrintAsmOperand(MI, OpNo, AsmVariant, ExtraCode, O);
    case 'c': // Don't print "$" before a global var name or constant.
      break; // PPC never has a prefix.
    case 'L': // Write second word of DImode reference.
      // Verify that this operand has two consecutive registers.
      if (!MI->getOperand(OpNo).isReg() ||
          OpNo+1 == MI->getNumOperands() ||
          !MI->getOperand(OpNo+1).isReg())
        return true;
      ++OpNo;   // Return the high-part.
      break;
    case 'I':
      // Write 'i' if an integer constant, otherwise nothing.  Used to print
      // addi vs add, etc.
      if (MI->getOperand(OpNo).isImm())
        O << "i";
      return false;
    case 'x':
      if(!MI->getOperand(OpNo).isReg())
        return true;
      // This operand uses VSX numbering.
      // If the operand is a VMX register, convert it to a VSX register.
      unsigned Reg = MI->getOperand(OpNo).getReg();
      if (PPCInstrInfo::isVRRegister(Reg))
        Reg = PPC::VSX32 + (Reg - PPC::V0);
      else if (PPCInstrInfo::isVFRegister(Reg))
        Reg = PPC::VSX32 + (Reg - PPC::VF0);
      const char *RegName;
      RegName = PPCInstPrinter::getRegisterName(Reg);
      RegName = PPCRegisterInfo::stripRegisterPrefix(RegName);
      O << RegName;
      return false;
    }
  }

  printOperand(MI, OpNo, O);
  return false;
}

// At the moment, all inline asm memory operands are a single register.
// In any case, the output of this routine should always be just one
// assembler operand.

bool PPCAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
                                          unsigned AsmVariant,
                                          const char *ExtraCode,
                                          raw_ostream &O) {
  if (ExtraCode && ExtraCode[0]) {
    if (ExtraCode[1] != 0) return true; // Unknown modifier.

    switch (ExtraCode[0]) {
    default: return true;  // Unknown modifier.
    case 'y': // A memory reference for an X-form instruction
      {
        const char *RegName = "r0";
        if (!Subtarget->isDarwin())
          RegName = PPCRegisterInfo::stripRegisterPrefix(RegName);
        O << RegName << ", ";
        printOperand(MI, OpNo, O);
        return false;
      }
    case 'U': // Print 'u' for update form.
    case 'X': // Print 'x' for indexed form.
    {
      // FIXME: Currently for PowerPC memory operands are always loaded
      // into a register, so we never get an update or indexed form.
      // This is bad even for offset forms, since even if we know we
      // have a value in -16(r1), we will generate a load into r<n>
      // and then load from 0(r<n>).  Until that issue is fixed,
      // tolerate 'U' and 'X' but don't output anything.
      assert(MI->getOperand(OpNo).isReg());
      return false;
    }
    }
  }

  assert(MI->getOperand(OpNo).isReg());
  O << "0(";
  printOperand(MI, OpNo, O);
  O << ")";
  return false;
}

/// lookUpOrCreateTOCEntry -- Given a symbol, look up whether a TOC entry
/// exists for it.  If not, create one.  Then return a symbol that references
/// the TOC entry.
MCSymbol *PPCAsmPrinter::lookUpOrCreateTOCEntry(MCSymbol *Sym) {
  MCSymbol *&TOCEntry = TOC[Sym];
  if (!TOCEntry)
    TOCEntry = createTempSymbol("C");
  return TOCEntry;
}

void PPCAsmPrinter::EmitEndOfAsmFile(Module &M) {
  emitStackMaps(SM);
}

void PPCAsmPrinter::LowerSTACKMAP(StackMaps &SM, const MachineInstr &MI) {
  unsigned NumNOPBytes = MI.getOperand(1).getImm();

  SM.recordStackMap(MI);
  assert(NumNOPBytes % 4 == 0 && "Invalid number of NOP bytes requested!");

  // Scan ahead to trim the shadow.
  const MachineBasicBlock &MBB = *MI.getParent();
  MachineBasicBlock::const_iterator MII(MI);
  ++MII;
  while (NumNOPBytes > 0) {
    if (MII == MBB.end() || MII->isCall() ||
        MII->getOpcode() == PPC::DBG_VALUE ||
        MII->getOpcode() == TargetOpcode::PATCHPOINT ||
        MII->getOpcode() == TargetOpcode::STACKMAP)
      break;
    ++MII;
    NumNOPBytes -= 4;
  }

  // Emit nops.
  for (unsigned i = 0; i < NumNOPBytes; i += 4)
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::NOP));
}

// Lower a patchpoint of the form:
// [<def>], <id>, <numBytes>, <target>, <numArgs>
void PPCAsmPrinter::LowerPATCHPOINT(StackMaps &SM, const MachineInstr &MI) {
  SM.recordPatchPoint(MI);
  PatchPointOpers Opers(&MI);

  unsigned EncodedBytes = 0;
  const MachineOperand &CalleeMO = Opers.getCallTarget();

  if (CalleeMO.isImm()) {
    int64_t CallTarget = CalleeMO.getImm();
    if (CallTarget) {
      assert((CallTarget & 0xFFFFFFFFFFFF) == CallTarget &&
             "High 16 bits of call target should be zero.");
      unsigned ScratchReg = MI.getOperand(Opers.getNextScratchIdx()).getReg();
      EncodedBytes = 0;
      // Materialize the jump address:
      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::LI8)
                                      .addReg(ScratchReg)
                                      .addImm((CallTarget >> 32) & 0xFFFF));
      ++EncodedBytes;
      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::RLDIC)
                                      .addReg(ScratchReg)
                                      .addReg(ScratchReg)
                                      .addImm(32).addImm(16));
      ++EncodedBytes;
      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ORIS8)
                                      .addReg(ScratchReg)
                                      .addReg(ScratchReg)
                                      .addImm((CallTarget >> 16) & 0xFFFF));
      ++EncodedBytes;
      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ORI8)
                                      .addReg(ScratchReg)
                                      .addReg(ScratchReg)
                                      .addImm(CallTarget & 0xFFFF));

      // Save the current TOC pointer before the remote call.
      int TOCSaveOffset = Subtarget->getFrameLowering()->getTOCSaveOffset();
      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::STD)
                                      .addReg(PPC::X2)
                                      .addImm(TOCSaveOffset)
                                      .addReg(PPC::X1));
      ++EncodedBytes;

      // If we're on ELFv1, then we need to load the actual function pointer
      // from the function descriptor.
      if (!Subtarget->isELFv2ABI()) {
        // Load the new TOC pointer and the function address, but not r11
        // (needing this is rare, and loading it here would prevent passing it
        // via a 'nest' parameter.
        EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::LD)
                                        .addReg(PPC::X2)
                                        .addImm(8)
                                        .addReg(ScratchReg));
        ++EncodedBytes;
        EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::LD)
                                        .addReg(ScratchReg)
                                        .addImm(0)
                                        .addReg(ScratchReg));
        ++EncodedBytes;
      }

      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::MTCTR8)
                                      .addReg(ScratchReg));
      ++EncodedBytes;
      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::BCTRL8));
      ++EncodedBytes;

      // Restore the TOC pointer after the call.
      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::LD)
                                      .addReg(PPC::X2)
                                      .addImm(TOCSaveOffset)
                                      .addReg(PPC::X1));
      ++EncodedBytes;
    }
  } else if (CalleeMO.isGlobal()) {
    const GlobalValue *GValue = CalleeMO.getGlobal();
    MCSymbol *MOSymbol = getSymbol(GValue);
    const MCExpr *SymVar = MCSymbolRefExpr::create(MOSymbol, OutContext);

    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::BL8_NOP)
                                    .addExpr(SymVar));
    EncodedBytes += 2;
  }

  // Each instruction is 4 bytes.
  EncodedBytes *= 4;

  // Emit padding.
  unsigned NumBytes = Opers.getNumPatchBytes();
  assert(NumBytes >= EncodedBytes &&
         "Patchpoint can't request size less than the length of a call.");
  assert((NumBytes - EncodedBytes) % 4 == 0 &&
         "Invalid number of NOP bytes requested!");
  for (unsigned i = EncodedBytes; i < NumBytes; i += 4)
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::NOP));
}

/// EmitTlsCall -- Given a GETtls[ld]ADDR[32] instruction, print a
/// call to __tls_get_addr to the current output stream.
void PPCAsmPrinter::EmitTlsCall(const MachineInstr *MI,
                                MCSymbolRefExpr::VariantKind VK) {
  StringRef Name = "__tls_get_addr";
  MCSymbol *TlsGetAddr = OutContext.getOrCreateSymbol(Name);
  MCSymbolRefExpr::VariantKind Kind = MCSymbolRefExpr::VK_None;

  assert(MI->getOperand(0).isReg() &&
         ((Subtarget->isPPC64() && MI->getOperand(0).getReg() == PPC::X3) ||
          (!Subtarget->isPPC64() && MI->getOperand(0).getReg() == PPC::R3)) &&
         "GETtls[ld]ADDR[32] must define GPR3");
  assert(MI->getOperand(1).isReg() &&
         ((Subtarget->isPPC64() && MI->getOperand(1).getReg() == PPC::X3) ||
          (!Subtarget->isPPC64() && MI->getOperand(1).getReg() == PPC::R3)) &&
         "GETtls[ld]ADDR[32] must read GPR3");

  if (!Subtarget->isPPC64() && !Subtarget->isDarwin() &&
      isPositionIndependent())
    Kind = MCSymbolRefExpr::VK_PLT;
  const MCExpr *TlsRef =
    MCSymbolRefExpr::create(TlsGetAddr, Kind, OutContext);

  // Add 32768 offset to the symbol so we follow up the latest GOT/PLT ABI.
  if (Kind == MCSymbolRefExpr::VK_PLT && Subtarget->isSecurePlt())
    TlsRef = MCBinaryExpr::createAdd(TlsRef,
                                     MCConstantExpr::create(32768, OutContext),
                                     OutContext);
  const MachineOperand &MO = MI->getOperand(2);
  const GlobalValue *GValue = MO.getGlobal();
  MCSymbol *MOSymbol = getSymbol(GValue);
  const MCExpr *SymVar = MCSymbolRefExpr::create(MOSymbol, VK, OutContext);
  EmitToStreamer(*OutStreamer,
                 MCInstBuilder(Subtarget->isPPC64() ?
                               PPC::BL8_NOP_TLS : PPC::BL_TLS)
                 .addExpr(TlsRef)
                 .addExpr(SymVar));
}

/// EmitInstruction -- Print out a single PowerPC MI in Darwin syntax to
/// the current output stream.
///
void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
  MCInst TmpInst;
  bool isPPC64 = Subtarget->isPPC64();
  bool isDarwin = TM.getTargetTriple().isOSDarwin();
  const Module *M = MF->getFunction().getParent();
  PICLevel::Level PL = M->getPICLevel();

#ifndef NDEBUG
  // Validate that SPE and FPU are mutually exclusive in codegen
  if (!MI->isInlineAsm()) {
    for (const MachineOperand &MO: MI->operands()) {
      if (MO.isReg()) {
        unsigned Reg = MO.getReg();
        if (Subtarget->hasSPE()) {
          if (PPC::F4RCRegClass.contains(Reg) ||
              PPC::F8RCRegClass.contains(Reg) ||
              PPC::QBRCRegClass.contains(Reg) ||
              PPC::QFRCRegClass.contains(Reg) ||
              PPC::QSRCRegClass.contains(Reg) ||
              PPC::VFRCRegClass.contains(Reg) ||
              PPC::VRRCRegClass.contains(Reg) ||
              PPC::VSFRCRegClass.contains(Reg) ||
              PPC::VSSRCRegClass.contains(Reg)
              )
            llvm_unreachable("SPE targets cannot have FPRegs!");
        } else {
          if (PPC::SPERCRegClass.contains(Reg))
            llvm_unreachable("SPE register found in FPU-targeted code!");
        }
      }
    }
  }
#endif
  // Lower multi-instruction pseudo operations.
  switch (MI->getOpcode()) {
  default: break;
  case TargetOpcode::DBG_VALUE:
    llvm_unreachable("Should be handled target independently");
  case TargetOpcode::STACKMAP:
    return LowerSTACKMAP(SM, *MI);
  case TargetOpcode::PATCHPOINT:
    return LowerPATCHPOINT(SM, *MI);

  case PPC::MoveGOTtoLR: {
    // Transform %lr = MoveGOTtoLR
    // Into this: bl _GLOBAL_OFFSET_TABLE_@local-4
    // _GLOBAL_OFFSET_TABLE_@local-4 (instruction preceding
    // _GLOBAL_OFFSET_TABLE_) has exactly one instruction:
    //      blrl
    // This will return the pointer to _GLOBAL_OFFSET_TABLE_@local
    MCSymbol *GOTSymbol =
      OutContext.getOrCreateSymbol(StringRef("_GLOBAL_OFFSET_TABLE_"));
    const MCExpr *OffsExpr =
      MCBinaryExpr::createSub(MCSymbolRefExpr::create(GOTSymbol,
                                                      MCSymbolRefExpr::VK_PPC_LOCAL,
                                                      OutContext),
                              MCConstantExpr::create(4, OutContext),
                              OutContext);

    // Emit the 'bl'.
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::BL).addExpr(OffsExpr));
    return;
  }
  case PPC::MovePCtoLR:
  case PPC::MovePCtoLR8: {
    // Transform %lr = MovePCtoLR
    // Into this, where the label is the PIC base:
    //     bl L1$pb
    // L1$pb:
    MCSymbol *PICBase = MF->getPICBaseSymbol();

    // Emit the 'bl'.
    EmitToStreamer(*OutStreamer,
                   MCInstBuilder(PPC::BL)
                       // FIXME: We would like an efficient form for this, so we
                       // don't have to do a lot of extra uniquing.
                       .addExpr(MCSymbolRefExpr::create(PICBase, OutContext)));

    // Emit the label.
    OutStreamer->EmitLabel(PICBase);
    return;
  }
  case PPC::UpdateGBR: {
    // Transform %rd = UpdateGBR(%rt, %ri)
    // Into: lwz %rt, .L0$poff - .L0$pb(%ri)
    //       add %rd, %rt, %ri
    // or into (if secure plt mode is on):
    //       addis r30, r30, .LTOC - .L0$pb@ha
    //       addi r30, r30, .LTOC - .L0$pb@l
    // Get the offset from the GOT Base Register to the GOT
    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);
    if (Subtarget->isSecurePlt() && isPositionIndependent() ) {
      unsigned PICR = TmpInst.getOperand(0).getReg();
      MCSymbol *LTOCSymbol = OutContext.getOrCreateSymbol(StringRef(".LTOC"));
      const MCExpr *PB =
        MCSymbolRefExpr::create(MF->getPICBaseSymbol(),
                                OutContext);

      const MCExpr *LTOCDeltaExpr =
        MCBinaryExpr::createSub(MCSymbolRefExpr::create(LTOCSymbol, OutContext),
                                PB, OutContext);

      const MCExpr *LTOCDeltaHi =
        PPCMCExpr::createHa(LTOCDeltaExpr, false, OutContext);
      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADDIS)
                                   .addReg(PICR)
                                   .addReg(PICR)
                                   .addExpr(LTOCDeltaHi));

      const MCExpr *LTOCDeltaLo =
        PPCMCExpr::createLo(LTOCDeltaExpr, false, OutContext);
      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADDI)
                                   .addReg(PICR)
                                   .addReg(PICR)
                                   .addExpr(LTOCDeltaLo));
      return;
    } else {
      MCSymbol *PICOffset =
        MF->getInfo<PPCFunctionInfo>()->getPICOffsetSymbol();
      TmpInst.setOpcode(PPC::LWZ);
      const MCExpr *Exp =
        MCSymbolRefExpr::create(PICOffset, MCSymbolRefExpr::VK_None, OutContext);
      const MCExpr *PB =
        MCSymbolRefExpr::create(MF->getPICBaseSymbol(),
                                MCSymbolRefExpr::VK_None,
                                OutContext);
      const MCOperand TR = TmpInst.getOperand(1);
      const MCOperand PICR = TmpInst.getOperand(0);

      // Step 1: lwz %rt, .L$poff - .L$pb(%ri)
      TmpInst.getOperand(1) =
          MCOperand::createExpr(MCBinaryExpr::createSub(Exp, PB, OutContext));
      TmpInst.getOperand(0) = TR;
      TmpInst.getOperand(2) = PICR;
      EmitToStreamer(*OutStreamer, TmpInst);

      TmpInst.setOpcode(PPC::ADD4);
      TmpInst.getOperand(0) = PICR;
      TmpInst.getOperand(1) = TR;
      TmpInst.getOperand(2) = PICR;
      EmitToStreamer(*OutStreamer, TmpInst);
      return;
    }
  }
  case PPC::LWZtoc: {
    // Transform %r3 = LWZtoc @min1, %r2
    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);

    // Change the opcode to LWZ, and the global address operand to be a
    // reference to the GOT entry we will synthesize later.
    TmpInst.setOpcode(PPC::LWZ);
    const MachineOperand &MO = MI->getOperand(1);

    // Map symbol -> label of TOC entry
    assert(MO.isGlobal() || MO.isCPI() || MO.isJTI() || MO.isBlockAddress());
    MCSymbol *MOSymbol = nullptr;
    if (MO.isGlobal())
      MOSymbol = getSymbol(MO.getGlobal());
    else if (MO.isCPI())
      MOSymbol = GetCPISymbol(MO.getIndex());
    else if (MO.isJTI())
      MOSymbol = GetJTISymbol(MO.getIndex());
    else if (MO.isBlockAddress())
      MOSymbol = GetBlockAddressSymbol(MO.getBlockAddress());

    if (PL == PICLevel::SmallPIC) {
      const MCExpr *Exp =
        MCSymbolRefExpr::create(MOSymbol, MCSymbolRefExpr::VK_GOT,
                                OutContext);
      TmpInst.getOperand(1) = MCOperand::createExpr(Exp);
    } else {
      MCSymbol *TOCEntry = lookUpOrCreateTOCEntry(MOSymbol);

      const MCExpr *Exp =
        MCSymbolRefExpr::create(TOCEntry, MCSymbolRefExpr::VK_None,
                                OutContext);
      const MCExpr *PB =
        MCSymbolRefExpr::create(OutContext.getOrCreateSymbol(Twine(".LTOC")),
                                                             OutContext);
      Exp = MCBinaryExpr::createSub(Exp, PB, OutContext);
      TmpInst.getOperand(1) = MCOperand::createExpr(Exp);
    }
    EmitToStreamer(*OutStreamer, TmpInst);
    return;
  }
  case PPC::LDtocJTI:
  case PPC::LDtocCPT:
  case PPC::LDtocBA:
  case PPC::LDtoc: {
    // Transform %x3 = LDtoc @min1, %x2
    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);

    // Change the opcode to LD, and the global address operand to be a
    // reference to the TOC entry we will synthesize later.
    TmpInst.setOpcode(PPC::LD);
    const MachineOperand &MO = MI->getOperand(1);

    // Map symbol -> label of TOC entry
    assert(MO.isGlobal() || MO.isCPI() || MO.isJTI() || MO.isBlockAddress());
    MCSymbol *MOSymbol = nullptr;
    if (MO.isGlobal())
      MOSymbol = getSymbol(MO.getGlobal());
    else if (MO.isCPI())
      MOSymbol = GetCPISymbol(MO.getIndex());
    else if (MO.isJTI())
      MOSymbol = GetJTISymbol(MO.getIndex());
    else if (MO.isBlockAddress())
      MOSymbol = GetBlockAddressSymbol(MO.getBlockAddress());

    MCSymbol *TOCEntry = lookUpOrCreateTOCEntry(MOSymbol);

    const MCExpr *Exp =
      MCSymbolRefExpr::create(TOCEntry, MCSymbolRefExpr::VK_PPC_TOC,
                              OutContext);
    TmpInst.getOperand(1) = MCOperand::createExpr(Exp);
    EmitToStreamer(*OutStreamer, TmpInst);
    return;
  }

  case PPC::ADDIStocHA: {
    // Transform %xd = ADDIStocHA %x2, @sym
    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);

    // Change the opcode to ADDIS8.  If the global address is external, has
    // common linkage, is a non-local function address, or is a jump table
    // address, then generate a TOC entry and reference that.  Otherwise
    // reference the symbol directly.
    TmpInst.setOpcode(PPC::ADDIS8);
    const MachineOperand &MO = MI->getOperand(2);
    assert((MO.isGlobal() || MO.isCPI() || MO.isJTI() ||
            MO.isBlockAddress()) &&
           "Invalid operand for ADDIStocHA!");
    MCSymbol *MOSymbol = nullptr;
    bool GlobalToc = false;

    if (MO.isGlobal()) {
      const GlobalValue *GV = MO.getGlobal();
      MOSymbol = getSymbol(GV);
      unsigned char GVFlags = Subtarget->classifyGlobalReference(GV);
      GlobalToc = (GVFlags & PPCII::MO_NLP_FLAG);
    } else if (MO.isCPI()) {
      MOSymbol = GetCPISymbol(MO.getIndex());
    } else if (MO.isJTI()) {
      MOSymbol = GetJTISymbol(MO.getIndex());
    } else if (MO.isBlockAddress()) {
      MOSymbol = GetBlockAddressSymbol(MO.getBlockAddress());
    }

    if (GlobalToc || MO.isJTI() || MO.isBlockAddress() ||
        TM.getCodeModel() == CodeModel::Large)
      MOSymbol = lookUpOrCreateTOCEntry(MOSymbol);

    const MCExpr *Exp =
      MCSymbolRefExpr::create(MOSymbol, MCSymbolRefExpr::VK_PPC_TOC_HA,
                              OutContext);

    if (!MO.isJTI() && MO.getOffset())
      Exp = MCBinaryExpr::createAdd(Exp,
                                    MCConstantExpr::create(MO.getOffset(),
                                                           OutContext),
                                    OutContext);

    TmpInst.getOperand(2) = MCOperand::createExpr(Exp);
    EmitToStreamer(*OutStreamer, TmpInst);
    return;
  }
  case PPC::LDtocL: {
    // Transform %xd = LDtocL @sym, %xs
    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);

    // Change the opcode to LD.  If the global address is external, has
    // common linkage, or is a jump table address, then reference the
    // associated TOC entry.  Otherwise reference the symbol directly.
    TmpInst.setOpcode(PPC::LD);
    const MachineOperand &MO = MI->getOperand(1);
    assert((MO.isGlobal() || MO.isCPI() || MO.isJTI() ||
            MO.isBlockAddress()) &&
           "Invalid operand for LDtocL!");
    MCSymbol *MOSymbol = nullptr;

    if (MO.isJTI())
      MOSymbol = lookUpOrCreateTOCEntry(GetJTISymbol(MO.getIndex()));
    else if (MO.isBlockAddress()) {
      MOSymbol = GetBlockAddressSymbol(MO.getBlockAddress());
      MOSymbol = lookUpOrCreateTOCEntry(MOSymbol);
    }
    else if (MO.isCPI()) {
      MOSymbol = GetCPISymbol(MO.getIndex());
      if (TM.getCodeModel() == CodeModel::Large)
        MOSymbol = lookUpOrCreateTOCEntry(MOSymbol);
    }
    else if (MO.isGlobal()) {
      const GlobalValue *GV = MO.getGlobal();
      MOSymbol = getSymbol(GV);
      LLVM_DEBUG(
          unsigned char GVFlags = Subtarget->classifyGlobalReference(GV);
          assert((GVFlags & PPCII::MO_NLP_FLAG) &&
                 "LDtocL used on symbol that could be accessed directly is "
                 "invalid. Must match ADDIStocHA."));
      MOSymbol = lookUpOrCreateTOCEntry(MOSymbol);
    }

    const MCExpr *Exp =
      MCSymbolRefExpr::create(MOSymbol, MCSymbolRefExpr::VK_PPC_TOC_LO,
                              OutContext);
    TmpInst.getOperand(1) = MCOperand::createExpr(Exp);
    EmitToStreamer(*OutStreamer, TmpInst);
    return;
  }
  case PPC::ADDItocL: {
    // Transform %xd = ADDItocL %xs, @sym
    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);

    // Change the opcode to ADDI8.  If the global address is external, then
    // generate a TOC entry and reference that.  Otherwise reference the
    // symbol directly.
    TmpInst.setOpcode(PPC::ADDI8);
    const MachineOperand &MO = MI->getOperand(2);
    assert((MO.isGlobal() || MO.isCPI()) && "Invalid operand for ADDItocL");
    MCSymbol *MOSymbol = nullptr;

    if (MO.isGlobal()) {
      const GlobalValue *GV = MO.getGlobal();
      LLVM_DEBUG(unsigned char GVFlags = Subtarget->classifyGlobalReference(GV);
                 assert(!(GVFlags & PPCII::MO_NLP_FLAG) &&
                        "Interposable definitions must use indirect access."));
      MOSymbol = getSymbol(GV);
    } else if (MO.isCPI()) {
      MOSymbol = GetCPISymbol(MO.getIndex());
    }

    const MCExpr *Exp =
      MCSymbolRefExpr::create(MOSymbol, MCSymbolRefExpr::VK_PPC_TOC_LO,
                              OutContext);
    TmpInst.getOperand(2) = MCOperand::createExpr(Exp);
    EmitToStreamer(*OutStreamer, TmpInst);
    return;
  }
  case PPC::ADDISgotTprelHA: {
    // Transform: %xd = ADDISgotTprelHA %x2, @sym
    // Into:      %xd = ADDIS8 %x2, sym@got@tlsgd@ha
    assert(Subtarget->isPPC64() && "Not supported for 32-bit PowerPC");
    const MachineOperand &MO = MI->getOperand(2);
    const GlobalValue *GValue = MO.getGlobal();
    MCSymbol *MOSymbol = getSymbol(GValue);
    const MCExpr *SymGotTprel =
      MCSymbolRefExpr::create(MOSymbol, MCSymbolRefExpr::VK_PPC_GOT_TPREL_HA,
                              OutContext);
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADDIS8)
                                 .addReg(MI->getOperand(0).getReg())
                                 .addReg(MI->getOperand(1).getReg())
                                 .addExpr(SymGotTprel));
    return;
  }
  case PPC::LDgotTprelL:
  case PPC::LDgotTprelL32: {
    // Transform %xd = LDgotTprelL @sym, %xs
    LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);

    // Change the opcode to LD.
    TmpInst.setOpcode(isPPC64 ? PPC::LD : PPC::LWZ);
    const MachineOperand &MO = MI->getOperand(1);
    const GlobalValue *GValue = MO.getGlobal();
    MCSymbol *MOSymbol = getSymbol(GValue);
    const MCExpr *Exp =
      MCSymbolRefExpr::create(MOSymbol, MCSymbolRefExpr::VK_PPC_GOT_TPREL_LO,
                              OutContext);
    TmpInst.getOperand(1) = MCOperand::createExpr(Exp);
    EmitToStreamer(*OutStreamer, TmpInst);
    return;
  }

  case PPC::PPC32PICGOT: {
    MCSymbol *GOTSymbol = OutContext.getOrCreateSymbol(StringRef("_GLOBAL_OFFSET_TABLE_"));
    MCSymbol *GOTRef = OutContext.createTempSymbol();
    MCSymbol *NextInstr = OutContext.createTempSymbol();

    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::BL)
      // FIXME: We would like an efficient form for this, so we don't have to do
      // a lot of extra uniquing.
      .addExpr(MCSymbolRefExpr::create(NextInstr, OutContext)));
    const MCExpr *OffsExpr =
      MCBinaryExpr::createSub(MCSymbolRefExpr::create(GOTSymbol, OutContext),
                                MCSymbolRefExpr::create(GOTRef, OutContext),
        OutContext);
    OutStreamer->EmitLabel(GOTRef);
    OutStreamer->EmitValue(OffsExpr, 4);
    OutStreamer->EmitLabel(NextInstr);
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::MFLR)
                                 .addReg(MI->getOperand(0).getReg()));
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::LWZ)
                                 .addReg(MI->getOperand(1).getReg())
                                 .addImm(0)
                                 .addReg(MI->getOperand(0).getReg()));
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADD4)
                                 .addReg(MI->getOperand(0).getReg())
                                 .addReg(MI->getOperand(1).getReg())
                                 .addReg(MI->getOperand(0).getReg()));
    return;
  }
  case PPC::PPC32GOT: {
    MCSymbol *GOTSymbol =
        OutContext.getOrCreateSymbol(StringRef("_GLOBAL_OFFSET_TABLE_"));
    const MCExpr *SymGotTlsL = MCSymbolRefExpr::create(
        GOTSymbol, MCSymbolRefExpr::VK_PPC_LO, OutContext);
    const MCExpr *SymGotTlsHA = MCSymbolRefExpr::create(
        GOTSymbol, MCSymbolRefExpr::VK_PPC_HA, OutContext);
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::LI)
                                 .addReg(MI->getOperand(0).getReg())
                                 .addExpr(SymGotTlsL));
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADDIS)
                                 .addReg(MI->getOperand(0).getReg())
                                 .addReg(MI->getOperand(0).getReg())
                                 .addExpr(SymGotTlsHA));
    return;
  }
  case PPC::ADDIStlsgdHA: {
    // Transform: %xd = ADDIStlsgdHA %x2, @sym
    // Into:      %xd = ADDIS8 %x2, sym@got@tlsgd@ha
    assert(Subtarget->isPPC64() && "Not supported for 32-bit PowerPC");
    const MachineOperand &MO = MI->getOperand(2);
    const GlobalValue *GValue = MO.getGlobal();
    MCSymbol *MOSymbol = getSymbol(GValue);
    const MCExpr *SymGotTlsGD =
      MCSymbolRefExpr::create(MOSymbol, MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HA,
                              OutContext);
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADDIS8)
                                 .addReg(MI->getOperand(0).getReg())
                                 .addReg(MI->getOperand(1).getReg())
                                 .addExpr(SymGotTlsGD));
    return;
  }
  case PPC::ADDItlsgdL:
    // Transform: %xd = ADDItlsgdL %xs, @sym
    // Into:      %xd = ADDI8 %xs, sym@got@tlsgd@l
  case PPC::ADDItlsgdL32: {
    // Transform: %rd = ADDItlsgdL32 %rs, @sym
    // Into:      %rd = ADDI %rs, sym@got@tlsgd
    const MachineOperand &MO = MI->getOperand(2);
    const GlobalValue *GValue = MO.getGlobal();
    MCSymbol *MOSymbol = getSymbol(GValue);
    const MCExpr *SymGotTlsGD = MCSymbolRefExpr::create(
        MOSymbol, Subtarget->isPPC64() ? MCSymbolRefExpr::VK_PPC_GOT_TLSGD_LO
                                       : MCSymbolRefExpr::VK_PPC_GOT_TLSGD,
        OutContext);
    EmitToStreamer(*OutStreamer,
                   MCInstBuilder(Subtarget->isPPC64() ? PPC::ADDI8 : PPC::ADDI)
                   .addReg(MI->getOperand(0).getReg())
                   .addReg(MI->getOperand(1).getReg())
                   .addExpr(SymGotTlsGD));
    return;
  }
  case PPC::GETtlsADDR:
    // Transform: %x3 = GETtlsADDR %x3, @sym
    // Into: BL8_NOP_TLS __tls_get_addr(sym at tlsgd)
  case PPC::GETtlsADDR32: {
    // Transform: %r3 = GETtlsADDR32 %r3, @sym
    // Into: BL_TLS __tls_get_addr(sym at tlsgd)@PLT
    EmitTlsCall(MI, MCSymbolRefExpr::VK_PPC_TLSGD);
    return;
  }
  case PPC::ADDIStlsldHA: {
    // Transform: %xd = ADDIStlsldHA %x2, @sym
    // Into:      %xd = ADDIS8 %x2, sym@got@tlsld@ha
    assert(Subtarget->isPPC64() && "Not supported for 32-bit PowerPC");
    const MachineOperand &MO = MI->getOperand(2);
    const GlobalValue *GValue = MO.getGlobal();
    MCSymbol *MOSymbol = getSymbol(GValue);
    const MCExpr *SymGotTlsLD =
      MCSymbolRefExpr::create(MOSymbol, MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HA,
                              OutContext);
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADDIS8)
                                 .addReg(MI->getOperand(0).getReg())
                                 .addReg(MI->getOperand(1).getReg())
                                 .addExpr(SymGotTlsLD));
    return;
  }
  case PPC::ADDItlsldL:
    // Transform: %xd = ADDItlsldL %xs, @sym
    // Into:      %xd = ADDI8 %xs, sym@got@tlsld@l
  case PPC::ADDItlsldL32: {
    // Transform: %rd = ADDItlsldL32 %rs, @sym
    // Into:      %rd = ADDI %rs, sym@got@tlsld
    const MachineOperand &MO = MI->getOperand(2);
    const GlobalValue *GValue = MO.getGlobal();
    MCSymbol *MOSymbol = getSymbol(GValue);
    const MCExpr *SymGotTlsLD = MCSymbolRefExpr::create(
        MOSymbol, Subtarget->isPPC64() ? MCSymbolRefExpr::VK_PPC_GOT_TLSLD_LO
                                       : MCSymbolRefExpr::VK_PPC_GOT_TLSLD,
        OutContext);
    EmitToStreamer(*OutStreamer,
                   MCInstBuilder(Subtarget->isPPC64() ? PPC::ADDI8 : PPC::ADDI)
                       .addReg(MI->getOperand(0).getReg())
                       .addReg(MI->getOperand(1).getReg())
                       .addExpr(SymGotTlsLD));
    return;
  }
  case PPC::GETtlsldADDR:
    // Transform: %x3 = GETtlsldADDR %x3, @sym
    // Into: BL8_NOP_TLS __tls_get_addr(sym at tlsld)
  case PPC::GETtlsldADDR32: {
    // Transform: %r3 = GETtlsldADDR32 %r3, @sym
    // Into: BL_TLS __tls_get_addr(sym at tlsld)@PLT
    EmitTlsCall(MI, MCSymbolRefExpr::VK_PPC_TLSLD);
    return;
  }
  case PPC::ADDISdtprelHA:
    // Transform: %xd = ADDISdtprelHA %xs, @sym
    // Into:      %xd = ADDIS8 %xs, sym@dtprel@ha
  case PPC::ADDISdtprelHA32: {
    // Transform: %rd = ADDISdtprelHA32 %rs, @sym
    // Into:      %rd = ADDIS %rs, sym@dtprel@ha
    const MachineOperand &MO = MI->getOperand(2);
    const GlobalValue *GValue = MO.getGlobal();
    MCSymbol *MOSymbol = getSymbol(GValue);
    const MCExpr *SymDtprel =
      MCSymbolRefExpr::create(MOSymbol, MCSymbolRefExpr::VK_PPC_DTPREL_HA,
                              OutContext);
    EmitToStreamer(
        *OutStreamer,
        MCInstBuilder(Subtarget->isPPC64() ? PPC::ADDIS8 : PPC::ADDIS)
            .addReg(MI->getOperand(0).getReg())
            .addReg(MI->getOperand(1).getReg())
            .addExpr(SymDtprel));
    return;
  }
  case PPC::ADDIdtprelL:
    // Transform: %xd = ADDIdtprelL %xs, @sym
    // Into:      %xd = ADDI8 %xs, sym@dtprel@l
  case PPC::ADDIdtprelL32: {
    // Transform: %rd = ADDIdtprelL32 %rs, @sym
    // Into:      %rd = ADDI %rs, sym@dtprel@l
    const MachineOperand &MO = MI->getOperand(2);
    const GlobalValue *GValue = MO.getGlobal();
    MCSymbol *MOSymbol = getSymbol(GValue);
    const MCExpr *SymDtprel =
      MCSymbolRefExpr::create(MOSymbol, MCSymbolRefExpr::VK_PPC_DTPREL_LO,
                              OutContext);
    EmitToStreamer(*OutStreamer,
                   MCInstBuilder(Subtarget->isPPC64() ? PPC::ADDI8 : PPC::ADDI)
                       .addReg(MI->getOperand(0).getReg())
                       .addReg(MI->getOperand(1).getReg())
                       .addExpr(SymDtprel));
    return;
  }
  case PPC::MFOCRF:
  case PPC::MFOCRF8:
    if (!Subtarget->hasMFOCRF()) {
      // Transform: %r3 = MFOCRF %cr7
      // Into:      %r3 = MFCR   ;; cr7
      unsigned NewOpcode =
        MI->getOpcode() == PPC::MFOCRF ? PPC::MFCR : PPC::MFCR8;
      OutStreamer->AddComment(PPCInstPrinter::
                              getRegisterName(MI->getOperand(1).getReg()));
      EmitToStreamer(*OutStreamer, MCInstBuilder(NewOpcode)
                                  .addReg(MI->getOperand(0).getReg()));
      return;
    }
    break;
  case PPC::MTOCRF:
  case PPC::MTOCRF8:
    if (!Subtarget->hasMFOCRF()) {
      // Transform: %cr7 = MTOCRF %r3
      // Into:      MTCRF mask, %r3 ;; cr7
      unsigned NewOpcode =
        MI->getOpcode() == PPC::MTOCRF ? PPC::MTCRF : PPC::MTCRF8;
      unsigned Mask = 0x80 >> OutContext.getRegisterInfo()
                              ->getEncodingValue(MI->getOperand(0).getReg());
      OutStreamer->AddComment(PPCInstPrinter::
                              getRegisterName(MI->getOperand(0).getReg()));
      EmitToStreamer(*OutStreamer, MCInstBuilder(NewOpcode)
                                     .addImm(Mask)
                                     .addReg(MI->getOperand(1).getReg()));
      return;
    }
    break;
  case PPC::LD:
  case PPC::STD:
  case PPC::LWA_32:
  case PPC::LWA: {
    // Verify alignment is legal, so we don't create relocations
    // that can't be supported.
    // FIXME:  This test is currently disabled for Darwin.  The test
    // suite shows a handful of test cases that fail this check for
    // Darwin.  Those need to be investigated before this sanity test
    // can be enabled for those subtargets.
    if (!Subtarget->isDarwin()) {
      unsigned OpNum = (MI->getOpcode() == PPC::STD) ? 2 : 1;
      const MachineOperand &MO = MI->getOperand(OpNum);
      if (MO.isGlobal() && MO.getGlobal()->getAlignment() < 4)
        llvm_unreachable("Global must be word-aligned for LD, STD, LWA!");
    }
    // Now process the instruction normally.
    break;
  }
  }

  LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);
  EmitToStreamer(*OutStreamer, TmpInst);
}

void PPCLinuxAsmPrinter::EmitInstruction(const MachineInstr *MI) {
  if (!Subtarget->isPPC64())
    return PPCAsmPrinter::EmitInstruction(MI);

  switch (MI->getOpcode()) {
  default:
    return PPCAsmPrinter::EmitInstruction(MI);
  case TargetOpcode::PATCHABLE_FUNCTION_ENTER: {
    // .begin:
    //   b .end # lis 0, FuncId[16..32]
    //   nop    # li  0, FuncId[0..15]
    //   std 0, -8(1)
    //   mflr 0
    //   bl __xray_FunctionEntry
    //   mtlr 0
    // .end:
    //
    // Update compiler-rt/lib/xray/xray_powerpc64.cc accordingly when number
    // of instructions change.
    MCSymbol *BeginOfSled = OutContext.createTempSymbol();
    MCSymbol *EndOfSled = OutContext.createTempSymbol();
    OutStreamer->EmitLabel(BeginOfSled);
    EmitToStreamer(*OutStreamer,
                   MCInstBuilder(PPC::B).addExpr(
                       MCSymbolRefExpr::create(EndOfSled, OutContext)));
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::NOP));
    EmitToStreamer(
        *OutStreamer,
        MCInstBuilder(PPC::STD).addReg(PPC::X0).addImm(-8).addReg(PPC::X1));
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::MFLR8).addReg(PPC::X0));
    EmitToStreamer(*OutStreamer,
                   MCInstBuilder(PPC::BL8_NOP)
                       .addExpr(MCSymbolRefExpr::create(
                           OutContext.getOrCreateSymbol("__xray_FunctionEntry"),
                           OutContext)));
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::MTLR8).addReg(PPC::X0));
    OutStreamer->EmitLabel(EndOfSled);
    recordSled(BeginOfSled, *MI, SledKind::FUNCTION_ENTER);
    break;
  }
  case TargetOpcode::PATCHABLE_RET: {
    unsigned RetOpcode = MI->getOperand(0).getImm();
    MCInst RetInst;
    RetInst.setOpcode(RetOpcode);
    for (const auto &MO :
         make_range(std::next(MI->operands_begin()), MI->operands_end())) {
      MCOperand MCOp;
      if (LowerPPCMachineOperandToMCOperand(MO, MCOp, *this, false))
        RetInst.addOperand(MCOp);
    }

    bool IsConditional;
    if (RetOpcode == PPC::BCCLR) {
      IsConditional = true;
    } else if (RetOpcode == PPC::TCRETURNdi8 || RetOpcode == PPC::TCRETURNri8 ||
               RetOpcode == PPC::TCRETURNai8) {
      break;
    } else if (RetOpcode == PPC::BLR8 || RetOpcode == PPC::TAILB8) {
      IsConditional = false;
    } else {
      EmitToStreamer(*OutStreamer, RetInst);
      break;
    }

    MCSymbol *FallthroughLabel;
    if (IsConditional) {
      // Before:
      //   bgtlr cr0
      //
      // After:
      //   ble cr0, .end
      // .p2align 3
      // .begin:
      //   blr    # lis 0, FuncId[16..32]
      //   nop    # li  0, FuncId[0..15]
      //   std 0, -8(1)
      //   mflr 0
      //   bl __xray_FunctionExit
      //   mtlr 0
      //   blr
      // .end:
      //
      // Update compiler-rt/lib/xray/xray_powerpc64.cc accordingly when number
      // of instructions change.
      FallthroughLabel = OutContext.createTempSymbol();
      EmitToStreamer(
          *OutStreamer,
          MCInstBuilder(PPC::BCC)
              .addImm(PPC::InvertPredicate(
                  static_cast<PPC::Predicate>(MI->getOperand(1).getImm())))
              .addReg(MI->getOperand(2).getReg())
              .addExpr(MCSymbolRefExpr::create(FallthroughLabel, OutContext)));
      RetInst = MCInst();
      RetInst.setOpcode(PPC::BLR8);
    }
    // .p2align 3
    // .begin:
    //   b(lr)? # lis 0, FuncId[16..32]
    //   nop    # li  0, FuncId[0..15]
    //   std 0, -8(1)
    //   mflr 0
    //   bl __xray_FunctionExit
    //   mtlr 0
    //   b(lr)?
    //
    // Update compiler-rt/lib/xray/xray_powerpc64.cc accordingly when number
    // of instructions change.
    OutStreamer->EmitCodeAlignment(8);
    MCSymbol *BeginOfSled = OutContext.createTempSymbol();
    OutStreamer->EmitLabel(BeginOfSled);
    EmitToStreamer(*OutStreamer, RetInst);
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::NOP));
    EmitToStreamer(
        *OutStreamer,
        MCInstBuilder(PPC::STD).addReg(PPC::X0).addImm(-8).addReg(PPC::X1));
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::MFLR8).addReg(PPC::X0));
    EmitToStreamer(*OutStreamer,
                   MCInstBuilder(PPC::BL8_NOP)
                       .addExpr(MCSymbolRefExpr::create(
                           OutContext.getOrCreateSymbol("__xray_FunctionExit"),
                           OutContext)));
    EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::MTLR8).addReg(PPC::X0));
    EmitToStreamer(*OutStreamer, RetInst);
    if (IsConditional)
      OutStreamer->EmitLabel(FallthroughLabel);
    recordSled(BeginOfSled, *MI, SledKind::FUNCTION_EXIT);
    break;
  }
  case TargetOpcode::PATCHABLE_FUNCTION_EXIT:
    llvm_unreachable("PATCHABLE_FUNCTION_EXIT should never be emitted");
  case TargetOpcode::PATCHABLE_TAIL_CALL:
    // TODO: Define a trampoline `__xray_FunctionTailExit` and differentiate a
    // normal function exit from a tail exit.
    llvm_unreachable("Tail call is handled in the normal case. See comments "
                     "around this assert.");
  }
}

void PPCLinuxAsmPrinter::EmitStartOfAsmFile(Module &M) {
  if (static_cast<const PPCTargetMachine &>(TM).isELFv2ABI()) {
    PPCTargetStreamer *TS =
      static_cast<PPCTargetStreamer *>(OutStreamer->getTargetStreamer());

    if (TS)
      TS->emitAbiVersion(2);
  }

  if (static_cast<const PPCTargetMachine &>(TM).isPPC64() ||
      !isPositionIndependent())
    return AsmPrinter::EmitStartOfAsmFile(M);

  if (M.getPICLevel() == PICLevel::SmallPIC)
    return AsmPrinter::EmitStartOfAsmFile(M);

  OutStreamer->SwitchSection(OutContext.getELFSection(
      ".got2", ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC));

  MCSymbol *TOCSym = OutContext.getOrCreateSymbol(Twine(".LTOC"));
  MCSymbol *CurrentPos = OutContext.createTempSymbol();

  OutStreamer->EmitLabel(CurrentPos);

  // The GOT pointer points to the middle of the GOT, in order to reference the
  // entire 64kB range.  0x8000 is the midpoint.
  const MCExpr *tocExpr =
    MCBinaryExpr::createAdd(MCSymbolRefExpr::create(CurrentPos, OutContext),
                            MCConstantExpr::create(0x8000, OutContext),
                            OutContext);

  OutStreamer->EmitAssignment(TOCSym, tocExpr);

  OutStreamer->SwitchSection(getObjFileLowering().getTextSection());
}

void PPCLinuxAsmPrinter::EmitFunctionEntryLabel() {
  // linux/ppc32 - Normal entry label.
  if (!Subtarget->isPPC64() &&
      (!isPositionIndependent() ||
       MF->getFunction().getParent()->getPICLevel() == PICLevel::SmallPIC))
    return AsmPrinter::EmitFunctionEntryLabel();

  if (!Subtarget->isPPC64()) {
    const PPCFunctionInfo *PPCFI = MF->getInfo<PPCFunctionInfo>();
    if (PPCFI->usesPICBase() && !Subtarget->isSecurePlt()) {
      MCSymbol *RelocSymbol = PPCFI->getPICOffsetSymbol();
      MCSymbol *PICBase = MF->getPICBaseSymbol();
      OutStreamer->EmitLabel(RelocSymbol);

      const MCExpr *OffsExpr =
        MCBinaryExpr::createSub(
          MCSymbolRefExpr::create(OutContext.getOrCreateSymbol(Twine(".LTOC")),
                                                               OutContext),
                                  MCSymbolRefExpr::create(PICBase, OutContext),
          OutContext);
      OutStreamer->EmitValue(OffsExpr, 4);
      OutStreamer->EmitLabel(CurrentFnSym);
      return;
    } else
      return AsmPrinter::EmitFunctionEntryLabel();
  }

  // ELFv2 ABI - Normal entry label.
  if (Subtarget->isELFv2ABI()) {
    // In the Large code model, we allow arbitrary displacements between
    // the text section and its associated TOC section.  We place the
    // full 8-byte offset to the TOC in memory immediately preceding
    // the function global entry point.
    if (TM.getCodeModel() == CodeModel::Large
        && !MF->getRegInfo().use_empty(PPC::X2)) {
      const PPCFunctionInfo *PPCFI = MF->getInfo<PPCFunctionInfo>();

      MCSymbol *TOCSymbol = OutContext.getOrCreateSymbol(StringRef(".TOC."));
      MCSymbol *GlobalEPSymbol = PPCFI->getGlobalEPSymbol();
      const MCExpr *TOCDeltaExpr =
        MCBinaryExpr::createSub(MCSymbolRefExpr::create(TOCSymbol, OutContext),
                                MCSymbolRefExpr::create(GlobalEPSymbol,
                                                        OutContext),
                                OutContext);

      OutStreamer->EmitLabel(PPCFI->getTOCOffsetSymbol());
      OutStreamer->EmitValue(TOCDeltaExpr, 8);
    }
    return AsmPrinter::EmitFunctionEntryLabel();
  }

  // Emit an official procedure descriptor.
  MCSectionSubPair Current = OutStreamer->getCurrentSection();
  MCSectionELF *Section = OutStreamer->getContext().getELFSection(
      ".opd", ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
  OutStreamer->SwitchSection(Section);
  OutStreamer->EmitLabel(CurrentFnSym);
  OutStreamer->EmitValueToAlignment(8);
  MCSymbol *Symbol1 = CurrentFnSymForSize;
  // Generates a R_PPC64_ADDR64 (from FK_DATA_8) relocation for the function
  // entry point.
  OutStreamer->EmitValue(MCSymbolRefExpr::create(Symbol1, OutContext),
                         8 /*size*/);
  MCSymbol *Symbol2 = OutContext.getOrCreateSymbol(StringRef(".TOC."));
  // Generates a R_PPC64_TOC relocation for TOC base insertion.
  OutStreamer->EmitValue(
    MCSymbolRefExpr::create(Symbol2, MCSymbolRefExpr::VK_PPC_TOCBASE, OutContext),
    8/*size*/);
  // Emit a null environment pointer.
  OutStreamer->EmitIntValue(0, 8 /* size */);
  OutStreamer->SwitchSection(Current.first, Current.second);
}

bool PPCLinuxAsmPrinter::doFinalization(Module &M) {
  const DataLayout &DL = getDataLayout();

  bool isPPC64 = DL.getPointerSizeInBits() == 64;

  PPCTargetStreamer &TS =
      static_cast<PPCTargetStreamer &>(*OutStreamer->getTargetStreamer());

  if (!TOC.empty()) {
    MCSectionELF *Section;

    if (isPPC64)
      Section = OutStreamer->getContext().getELFSection(
          ".toc", ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
        else
          Section = OutStreamer->getContext().getELFSection(
              ".got2", ELF::SHT_PROGBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
    OutStreamer->SwitchSection(Section);

    for (MapVector<MCSymbol*, MCSymbol*>::iterator I = TOC.begin(),
         E = TOC.end(); I != E; ++I) {
      OutStreamer->EmitLabel(I->second);
      MCSymbol *S = I->first;
      if (isPPC64) {
        TS.emitTCEntry(*S);
      } else {
        OutStreamer->EmitValueToAlignment(4);
        OutStreamer->EmitSymbolValue(S, 4);
      }
    }
  }

  return AsmPrinter::doFinalization(M);
}

/// EmitFunctionBodyStart - Emit a global entry point prefix for ELFv2.
void PPCLinuxAsmPrinter::EmitFunctionBodyStart() {
  // In the ELFv2 ABI, in functions that use the TOC register, we need to
  // provide two entry points.  The ABI guarantees that when calling the
  // local entry point, r2 is set up by the caller to contain the TOC base
  // for this function, and when calling the global entry point, r12 is set
  // up by the caller to hold the address of the global entry point.  We
  // thus emit a prefix sequence along the following lines:
  //
  // func:
  // .Lfunc_gepNN:
  //         # global entry point
  //         addis r2,r12,(.TOC.-.Lfunc_gepNN)@ha
  //         addi  r2,r2,(.TOC.-.Lfunc_gepNN)@l
  // .Lfunc_lepNN:
  //         .localentry func, .Lfunc_lepNN-.Lfunc_gepNN
  //         # local entry point, followed by function body
  //
  // For the Large code model, we create
  //
  // .Lfunc_tocNN:
  //         .quad .TOC.-.Lfunc_gepNN      # done by EmitFunctionEntryLabel
  // func:
  // .Lfunc_gepNN:
  //         # global entry point
  //         ld    r2,.Lfunc_tocNN-.Lfunc_gepNN(r12)
  //         add   r2,r2,r12
  // .Lfunc_lepNN:
  //         .localentry func, .Lfunc_lepNN-.Lfunc_gepNN
  //         # local entry point, followed by function body
  //
  // This ensures we have r2 set up correctly while executing the function
  // body, no matter which entry point is called.
  if (Subtarget->isELFv2ABI()
      // Only do all that if the function uses r2 in the first place.
      && !MF->getRegInfo().use_empty(PPC::X2)) {
    // Note: The logic here must be synchronized with the code in the
    // branch-selection pass which sets the offset of the first block in the
    // function. This matters because it affects the alignment.
    const PPCFunctionInfo *PPCFI = MF->getInfo<PPCFunctionInfo>();

    MCSymbol *GlobalEntryLabel = PPCFI->getGlobalEPSymbol();
    OutStreamer->EmitLabel(GlobalEntryLabel);
    const MCSymbolRefExpr *GlobalEntryLabelExp =
      MCSymbolRefExpr::create(GlobalEntryLabel, OutContext);

    if (TM.getCodeModel() != CodeModel::Large) {
      MCSymbol *TOCSymbol = OutContext.getOrCreateSymbol(StringRef(".TOC."));
      const MCExpr *TOCDeltaExpr =
        MCBinaryExpr::createSub(MCSymbolRefExpr::create(TOCSymbol, OutContext),
                                GlobalEntryLabelExp, OutContext);

      const MCExpr *TOCDeltaHi =
        PPCMCExpr::createHa(TOCDeltaExpr, false, OutContext);
      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADDIS)
                                   .addReg(PPC::X2)
                                   .addReg(PPC::X12)
                                   .addExpr(TOCDeltaHi));

      const MCExpr *TOCDeltaLo =
        PPCMCExpr::createLo(TOCDeltaExpr, false, OutContext);
      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADDI)
                                   .addReg(PPC::X2)
                                   .addReg(PPC::X2)
                                   .addExpr(TOCDeltaLo));
    } else {
      MCSymbol *TOCOffset = PPCFI->getTOCOffsetSymbol();
      const MCExpr *TOCOffsetDeltaExpr =
        MCBinaryExpr::createSub(MCSymbolRefExpr::create(TOCOffset, OutContext),
                                GlobalEntryLabelExp, OutContext);

      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::LD)
                                   .addReg(PPC::X2)
                                   .addExpr(TOCOffsetDeltaExpr)
                                   .addReg(PPC::X12));
      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADD8)
                                   .addReg(PPC::X2)
                                   .addReg(PPC::X2)
                                   .addReg(PPC::X12));
    }

    MCSymbol *LocalEntryLabel = PPCFI->getLocalEPSymbol();
    OutStreamer->EmitLabel(LocalEntryLabel);
    const MCSymbolRefExpr *LocalEntryLabelExp =
       MCSymbolRefExpr::create(LocalEntryLabel, OutContext);
    const MCExpr *LocalOffsetExp =
      MCBinaryExpr::createSub(LocalEntryLabelExp,
                              GlobalEntryLabelExp, OutContext);

    PPCTargetStreamer *TS =
      static_cast<PPCTargetStreamer *>(OutStreamer->getTargetStreamer());

    if (TS)
      TS->emitLocalEntry(cast<MCSymbolELF>(CurrentFnSym), LocalOffsetExp);
  }
}

/// EmitFunctionBodyEnd - Print the traceback table before the .size
/// directive.
///
void PPCLinuxAsmPrinter::EmitFunctionBodyEnd() {
  // Only the 64-bit target requires a traceback table.  For now,
  // we only emit the word of zeroes that GDB requires to find
  // the end of the function, and zeroes for the eight-byte
  // mandatory fields.
  // FIXME: We should fill in the eight-byte mandatory fields as described in
  // the PPC64 ELF ABI (this is a low-priority item because GDB does not
  // currently make use of these fields).
  if (Subtarget->isPPC64()) {
    OutStreamer->EmitIntValue(0, 4/*size*/);
    OutStreamer->EmitIntValue(0, 8/*size*/);
  }
}

void PPCDarwinAsmPrinter::EmitStartOfAsmFile(Module &M) {
  static const char *const CPUDirectives[] = {
    "",
    "ppc",
    "ppc440",
    "ppc601",
    "ppc602",
    "ppc603",
    "ppc7400",
    "ppc750",
    "ppc970",
    "ppcA2",
    "ppce500",
    "ppce500mc",
    "ppce5500",
    "power3",
    "power4",
    "power5",
    "power5x",
    "power6",
    "power6x",
    "power7",
    // FIXME: why is power8 missing here?
    "ppc64",
    "ppc64le",
    "power9"
  };

  // Get the numerically largest directive.
  // FIXME: How should we merge darwin directives?
  unsigned Directive = PPC::DIR_NONE;
  for (const Function &F : M) {
    const PPCSubtarget &STI = TM.getSubtarget<PPCSubtarget>(F);
    unsigned FDir = STI.getDarwinDirective();
    Directive = Directive > FDir ? FDir : STI.getDarwinDirective();
    if (STI.hasMFOCRF() && Directive < PPC::DIR_970)
      Directive = PPC::DIR_970;
    if (STI.hasAltivec() && Directive < PPC::DIR_7400)
      Directive = PPC::DIR_7400;
    if (STI.isPPC64() && Directive < PPC::DIR_64)
      Directive = PPC::DIR_64;
  }

  assert(Directive <= PPC::DIR_64 && "Directive out of range.");

  assert(Directive < array_lengthof(CPUDirectives) &&
         "CPUDirectives[] might not be up-to-date!");
  PPCTargetStreamer &TStreamer =
      *static_cast<PPCTargetStreamer *>(OutStreamer->getTargetStreamer());
  TStreamer.emitMachine(CPUDirectives[Directive]);

  // Prime text sections so they are adjacent.  This reduces the likelihood a
  // large data or debug section causes a branch to exceed 16M limit.
  const TargetLoweringObjectFileMachO &TLOFMacho =
      static_cast<const TargetLoweringObjectFileMachO &>(getObjFileLowering());
  OutStreamer->SwitchSection(TLOFMacho.getTextCoalSection());
  if (TM.getRelocationModel() == Reloc::PIC_) {
    OutStreamer->SwitchSection(
           OutContext.getMachOSection("__TEXT", "__picsymbolstub1",
                                      MachO::S_SYMBOL_STUBS |
                                      MachO::S_ATTR_PURE_INSTRUCTIONS,
                                      32, SectionKind::getText()));
  } else if (TM.getRelocationModel() == Reloc::DynamicNoPIC) {
    OutStreamer->SwitchSection(
           OutContext.getMachOSection("__TEXT","__symbol_stub1",
                                      MachO::S_SYMBOL_STUBS |
                                      MachO::S_ATTR_PURE_INSTRUCTIONS,
                                      16, SectionKind::getText()));
  }
  OutStreamer->SwitchSection(getObjFileLowering().getTextSection());
}

bool PPCDarwinAsmPrinter::doFinalization(Module &M) {
  bool isPPC64 = getDataLayout().getPointerSizeInBits() == 64;

  // Darwin/PPC always uses mach-o.
  const TargetLoweringObjectFileMachO &TLOFMacho =
      static_cast<const TargetLoweringObjectFileMachO &>(getObjFileLowering());
  if (MMI) {
    MachineModuleInfoMachO &MMIMacho =
        MMI->getObjFileInfo<MachineModuleInfoMachO>();

    if (MAI->doesSupportExceptionHandling()) {
      // Add the (possibly multiple) personalities to the set of global values.
      // Only referenced functions get into the Personalities list.
      for (const Function *Personality : MMI->getPersonalities()) {
        if (Personality) {
          MCSymbol *NLPSym =
              getSymbolWithGlobalValueBase(Personality, "$non_lazy_ptr");
          MachineModuleInfoImpl::StubValueTy &StubSym =
              MMIMacho.getGVStubEntry(NLPSym);
          StubSym =
              MachineModuleInfoImpl::StubValueTy(getSymbol(Personality), true);
        }
      }
    }

    // Output stubs for dynamically-linked functions.
    MachineModuleInfoMachO::SymbolListTy Stubs = MMIMacho.GetGVStubList();

    // Output macho stubs for external and common global variables.
    if (!Stubs.empty()) {
      // Switch with ".non_lazy_symbol_pointer" directive.
      OutStreamer->SwitchSection(TLOFMacho.getNonLazySymbolPointerSection());
      EmitAlignment(isPPC64 ? 3 : 2);

      for (unsigned i = 0, e = Stubs.size(); i != e; ++i) {
        // L_foo$stub:
        OutStreamer->EmitLabel(Stubs[i].first);
        //   .indirect_symbol _foo
        MachineModuleInfoImpl::StubValueTy &MCSym = Stubs[i].second;
        OutStreamer->EmitSymbolAttribute(MCSym.getPointer(),
                                         MCSA_IndirectSymbol);

        if (MCSym.getInt())
          // External to current translation unit.
          OutStreamer->EmitIntValue(0, isPPC64 ? 8 : 4 /*size*/);
        else
          // Internal to current translation unit.
          //
          // When we place the LSDA into the TEXT section, the type info
          // pointers
          // need to be indirect and pc-rel. We accomplish this by using NLPs.
          // However, sometimes the types are local to the file. So we need to
          // fill in the value for the NLP in those cases.
          OutStreamer->EmitValue(
              MCSymbolRefExpr::create(MCSym.getPointer(), OutContext),
              isPPC64 ? 8 : 4 /*size*/);
      }

      Stubs.clear();
      OutStreamer->AddBlankLine();
    }
  }

  // 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.
  OutStreamer->EmitAssemblerFlag(MCAF_SubsectionsViaSymbols);

  return AsmPrinter::doFinalization(M);
}

/// createPPCAsmPrinterPass - Returns a pass that prints the PPC assembly code
/// for a MachineFunction to the given output stream, in a format that the
/// Darwin assembler can deal with.
///
static AsmPrinter *
createPPCAsmPrinterPass(TargetMachine &tm,
                        std::unique_ptr<MCStreamer> &&Streamer) {
  if (tm.getTargetTriple().isMacOSX())
    return new PPCDarwinAsmPrinter(tm, std::move(Streamer));
  return new PPCLinuxAsmPrinter(tm, std::move(Streamer));
}

// Force static initialization.
extern "C" void LLVMInitializePowerPCAsmPrinter() {
  TargetRegistry::RegisterAsmPrinter(getThePPC32Target(),
                                     createPPCAsmPrinterPass);
  TargetRegistry::RegisterAsmPrinter(getThePPC64Target(),
                                     createPPCAsmPrinterPass);
  TargetRegistry::RegisterAsmPrinter(getThePPC64LETarget(),
                                     createPPCAsmPrinterPass);
}