Initial revision

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@14283 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 694 insertions, 0 deletions

diff --git a/lib/Target/PowerPC/PowerPCAsmPrinter.cpp b/lib/Target/PowerPC/PowerPCAsmPrinter.cpp
new file mode 100644
index 0000000000..697be0907c
--- /dev/null
+++ b/lib/Target/PowerPC/PowerPCAsmPrinter.cpp
@@ -0,0 +1,694 @@
+//===-- PPC32/Printer.cpp - Convert X86 LLVM code to Intel assembly ---------===//
+// 
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file contains a printer that converts from our internal
+// representation of machine-dependent LLVM code to Intel-format
+// assembly language. This printer is the output mechanism used
+// by `llc' and `lli -print-machineinstrs' on X86.
+//
+//===----------------------------------------------------------------------===//
+
+#include <set>
+
+#include "PowerPC.h"
+#include "PowerPCInstrInfo.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Module.h"
+#include "llvm/Assembly/Writer.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineConstantPool.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Support/Mangler.h"
+#include "Support/Statistic.h"
+#include "Support/StringExtras.h"
+#include "Support/CommandLine.h"
+
+namespace llvm {
+
+namespace {
+  Statistic<> EmittedInsts("asm-printer", "Number of machine instrs printed");
+
+  struct Printer : public MachineFunctionPass {
+    /// Output stream on which we're printing assembly code.
+    ///
+    std::ostream &O;
+
+    /// Target machine description which we query for reg. names, data
+    /// layout, etc.
+    ///
+    TargetMachine &TM;
+
+    /// Name-mangler for global names.
+    ///
+    Mangler *Mang;
+    std::set< std::string > Stubs;
+    std::set<std::string> Strings;
+
+    Printer(std::ostream &o, TargetMachine &tm) : O(o), TM(tm) { }
+
+    /// We name each basic block in a Function with a unique number, so
+    /// that we can consistently refer to them later. This is cleared
+    /// at the beginning of each call to runOnMachineFunction().
+    ///
+    typedef std::map<const Value *, unsigned> ValueMapTy;
+    ValueMapTy NumberForBB;
+
+    /// Cache of mangled name for current function. This is
+    /// recalculated at the beginning of each call to
+    /// runOnMachineFunction().
+    ///
+    std::string CurrentFnName;
+
+    virtual const char *getPassName() const {
+      return "PowerPC Assembly Printer";
+    }
+
+    void printMachineInstruction(const MachineInstr *MI);
+    void printOp(const MachineOperand &MO,
+		 bool elideOffsetKeyword = false);
+    void printConstantPool(MachineConstantPool *MCP);
+    bool runOnMachineFunction(MachineFunction &F);    
+    bool doInitialization(Module &M);
+    bool doFinalization(Module &M);
+    void emitGlobalConstant(const Constant* CV);
+    void emitConstantValueOnly(const Constant *CV);
+  };
+} // end of anonymous namespace
+
+/// createPPCCodePrinterPass - Returns a pass that prints the X86
+/// assembly code for a MachineFunction to the given output stream,
+/// using the given target machine description.  This should work
+/// regardless of whether the function is in SSA form.
+///
+FunctionPass *createPPCCodePrinterPass(std::ostream &o,TargetMachine &tm){
+  return new Printer(o, tm);
+}
+
+/// isStringCompatible - Can we treat the specified array as a string?
+/// Only if it is an array of ubytes or non-negative sbytes.
+///
+static bool isStringCompatible(const ConstantArray *CVA) {
+  const Type *ETy = cast<ArrayType>(CVA->getType())->getElementType();
+  if (ETy == Type::UByteTy) return true;
+  if (ETy != Type::SByteTy) return false;
+
+  for (unsigned i = 0; i < CVA->getNumOperands(); ++i)
+    if (cast<ConstantSInt>(CVA->getOperand(i))->getValue() < 0)
+      return false;
+
+  return true;
+}
+
+/// toOctal - Convert the low order bits of X into an octal digit.
+///
+static inline char toOctal(int X) {
+  return (X&7)+'0';
+}
+
+/// getAsCString - Return the specified array as a C compatible
+/// string, only if the predicate isStringCompatible is true.
+///
+static void printAsCString(std::ostream &O, const ConstantArray *CVA) {
+  assert(isStringCompatible(CVA) && "Array is not string compatible!");
+
+  O << "\"";
+  for (unsigned i = 0; i < CVA->getNumOperands(); ++i) {
+    unsigned char C = cast<ConstantInt>(CVA->getOperand(i))->getRawValue();
+
+    if (C == '"') {
+      O << "\\\"";
+    } else if (C == '\\') {
+      O << "\\\\";
+    } else if (isprint(C)) {
+      O << C;
+    } else {
+      switch(C) {
+      case '\b': O << "\\b"; break;
+      case '\f': O << "\\f"; break;
+      case '\n': O << "\\n"; break;
+      case '\r': O << "\\r"; break;
+      case '\t': O << "\\t"; break;
+      default:
+        O << '\\';
+        O << toOctal(C >> 6);
+        O << toOctal(C >> 3);
+        O << toOctal(C >> 0);
+        break;
+      }
+    }
+  }
+  O << "\"";
+}
+
+// Print out the specified constant, without a storage class.  Only the
+// constants valid in constant expressions can occur here.
+void Printer::emitConstantValueOnly(const Constant *CV) {
+  if (CV->isNullValue())
+    O << "0";
+  else if (const ConstantBool *CB = dyn_cast<ConstantBool>(CV)) {
+    assert(CB == ConstantBool::True);
+    O << "1";
+  } else if (const ConstantSInt *CI = dyn_cast<ConstantSInt>(CV))
+    O << CI->getValue();
+  else if (const ConstantUInt *CI = dyn_cast<ConstantUInt>(CV))
+    O << CI->getValue();
+  else if (const ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(CV))
+    // This is a constant address for a global variable or function.  Use the
+    // name of the variable or function as the address value.
+    O << Mang->getValueName(CPR->getValue());
+  else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV)) {
+    const TargetData &TD = TM.getTargetData();
+    switch(CE->getOpcode()) {
+    case Instruction::GetElementPtr: {
+      // generate a symbolic expression for the byte address
+      const Constant *ptrVal = CE->getOperand(0);
+      std::vector<Value*> idxVec(CE->op_begin()+1, CE->op_end());
+      if (unsigned Offset = TD.getIndexedOffset(ptrVal->getType(), idxVec)) {
+        O << "(";
+        emitConstantValueOnly(ptrVal);
+        O << ") + " << Offset;
+      } else {
+        emitConstantValueOnly(ptrVal);
+      }
+      break;
+    }
+    case Instruction::Cast: {
+      // Support only non-converting or widening casts for now, that is, ones
+      // that do not involve a change in value.  This assertion is really gross,
+      // and may not even be a complete check.
+      Constant *Op = CE->getOperand(0);
+      const Type *OpTy = Op->getType(), *Ty = CE->getType();
+
+      // Remember, kids, pointers on x86 can be losslessly converted back and
+      // forth into 32-bit or wider integers, regardless of signedness. :-P
+      assert(((isa<PointerType>(OpTy)
+               && (Ty == Type::LongTy || Ty == Type::ULongTy
+                   || Ty == Type::IntTy || Ty == Type::UIntTy))
+              || (isa<PointerType>(Ty)
+                  && (OpTy == Type::LongTy || OpTy == Type::ULongTy
+                      || OpTy == Type::IntTy || OpTy == Type::UIntTy))
+              || (((TD.getTypeSize(Ty) >= TD.getTypeSize(OpTy))
+                   && OpTy->isLosslesslyConvertibleTo(Ty))))
+             && "FIXME: Don't yet support this kind of constant cast expr");
+      O << "(";
+      emitConstantValueOnly(Op);
+      O << ")";
+      break;
+    }
+    case Instruction::Add:
+      O << "(";
+      emitConstantValueOnly(CE->getOperand(0));
+      O << ") + (";
+      emitConstantValueOnly(CE->getOperand(1));
+      O << ")";
+      break;
+    default:
+      assert(0 && "Unsupported operator!");
+    }
+  } else {
+    assert(0 && "Unknown constant value!");
+  }
+}
+
+// Print a constant value or values, with the appropriate storage class as a
+// prefix.
+void Printer::emitGlobalConstant(const Constant *CV) {  
+  const TargetData &TD = TM.getTargetData();
+
+  if (CV->isNullValue()) {
+    O << "\t.space\t " << TD.getTypeSize(CV->getType()) << "\n";      
+    return;
+  } else if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV)) {
+    if (isStringCompatible(CVA)) {
+      O << ".ascii";
+      printAsCString(O, CVA);
+      O << "\n";
+    } else { // Not a string.  Print the values in successive locations
+      const std::vector<Use> &constValues = CVA->getValues();
+      for (unsigned i=0; i < constValues.size(); i++)
+        emitGlobalConstant(cast<Constant>(constValues[i].get()));
+    }
+    return;
+  } else if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV)) {
+    // Print the fields in successive locations. Pad to align if needed!
+    const StructLayout *cvsLayout = TD.getStructLayout(CVS->getType());
+    const std::vector<Use>& constValues = CVS->getValues();
+    unsigned sizeSoFar = 0;
+    for (unsigned i=0, N = constValues.size(); i < N; i++) {
+      const Constant* field = cast<Constant>(constValues[i].get());
+
+      // Check if padding is needed and insert one or more 0s.
+      unsigned fieldSize = TD.getTypeSize(field->getType());
+      unsigned padSize = ((i == N-1? cvsLayout->StructSize
+                           : cvsLayout->MemberOffsets[i+1])
+                          - cvsLayout->MemberOffsets[i]) - fieldSize;
+      sizeSoFar += fieldSize + padSize;
+
+      // Now print the actual field value
+      emitGlobalConstant(field);
+
+      // Insert the field padding unless it's zero bytes...
+      if (padSize)
+        O << "\t.space\t " << padSize << "\n";      
+    }
+    assert(sizeSoFar == cvsLayout->StructSize &&
+           "Layout of constant struct may be incorrect!");
+    return;
+  } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV)) {
+    // FP Constants are printed as integer constants to avoid losing
+    // precision...
+    double Val = CFP->getValue();
+    switch (CFP->getType()->getPrimitiveID()) {
+    default: assert(0 && "Unknown floating point type!");
+    case Type::FloatTyID: {
+      union FU {                            // Abide by C TBAA rules
+        float FVal;
+        unsigned UVal;
+      } U;
+      U.FVal = Val;
+      O << ".long\t" << U.UVal << "\t# float " << Val << "\n";
+      return;
+    }
+    case Type::DoubleTyID: {
+      union DU {                            // Abide by C TBAA rules
+        double FVal;
+        uint64_t UVal;
+        struct {
+        	uint32_t MSWord;
+        	uint32_t LSWord;
+        } T;
+      } U;
+      U.FVal = Val;
+      
+      O << ".long\t" << U.T.MSWord << "\t# double most significant word " << Val << "\n";
+      O << ".long\t" << U.T.LSWord << "\t# double least significant word" << Val << "\n";
+      return;
+    }
+    }
+  } else if (CV->getType()->getPrimitiveSize() == 64) {
+    const ConstantInt *CI = dyn_cast<ConstantInt>(CV);
+    if(CI) {
+  	union DU {                            // Abide by C TBAA rules
+        int64_t UVal;
+        struct {
+        	uint32_t MSWord;
+        	uint32_t LSWord;
+        } T;
+      } U;
+      U.UVal = CI->getRawValue();
+        
+      O << ".long\t" << U.T.MSWord << "\t# Double-word most significant word " << U.UVal << "\n";
+      O << ".long\t" << U.T.LSWord << "\t# Double-word least significant word" << U.UVal << "\n";
+      return;	  
+    }
+  }
+
+  const Type *type = CV->getType();
+  O << "\t";
+  switch (type->getPrimitiveID()) {
+  case Type::UByteTyID: case Type::SByteTyID:
+    O << ".byte";
+    break;
+  case Type::UShortTyID: case Type::ShortTyID:
+    O << ".short";
+    break;
+  case Type::BoolTyID: 
+  case Type::PointerTyID:
+  case Type::UIntTyID: case Type::IntTyID:
+    O << ".long";
+    break;
+  case Type::ULongTyID: case Type::LongTyID:    
+  	assert (0 && "Should have already output double-word constant.");
+  case Type::FloatTyID: case Type::DoubleTyID:
+    assert (0 && "Should have already output floating point constant.");
+  default:
+    assert (0 && "Can't handle printing this type of thing");
+    break;
+  }
+  O << "\t";
+  emitConstantValueOnly(CV);
+  O << "\n";
+}
+
+/// printConstantPool - Print to the current output stream assembly
+/// representations of the constants in the constant pool MCP. This is
+/// used to print out constants which have been "spilled to memory" by
+/// the code generator.
+///
+void Printer::printConstantPool(MachineConstantPool *MCP) {
+  const std::vector<Constant*> &CP = MCP->getConstants();
+  const TargetData &TD = TM.getTargetData();
+ 
+  if (CP.empty()) return;
+
+  for (unsigned i = 0, e = CP.size(); i != e; ++i) {
+    O << "\t.const\n";
+    O << "\t.align " << (unsigned)TD.getTypeAlignment(CP[i]->getType())
+      << "\n";
+    O << ".CPI" << CurrentFnName << "_" << i << ":\t\t\t\t\t#"
+      << *CP[i] << "\n";
+    emitGlobalConstant(CP[i]);
+  }
+}
+
+/// runOnMachineFunction - This uses the printMachineInstruction()
+/// method to print assembly for each instruction.
+///
+bool Printer::runOnMachineFunction(MachineFunction &MF) {
+  // BBNumber is used here so that a given Printer will never give two
+  // BBs the same name. (If you have a better way, please let me know!)
+  static unsigned BBNumber = 0;
+
+  O << "\n\n";
+  // What's my mangled name?
+  CurrentFnName = Mang->getValueName(MF.getFunction());
+
+  // Print out constants referenced by the function
+  printConstantPool(MF.getConstantPool());
+
+  // Print out labels for the function.
+  O << "\t.text\n"; 
+  O << "\t.globl\t" << CurrentFnName << "\n";
+  O << "\t.align 5\n";
+  O << CurrentFnName << ":\n";
+
+  // Number each basic block so that we can consistently refer to them
+  // in PC-relative references.
+  NumberForBB.clear();
+  for (MachineFunction::const_iterator I = MF.begin(), E = MF.end();
+       I != E; ++I) {
+    NumberForBB[I->getBasicBlock()] = BBNumber++;
+  }
+
+  // Print out code for the function.
+  for (MachineFunction::const_iterator I = MF.begin(), E = MF.end();
+       I != E; ++I) {
+    // Print a label for the basic block.
+    O << "L" << NumberForBB[I->getBasicBlock()] << ":\t# "
+      << I->getBasicBlock()->getName() << "\n";
+    for (MachineBasicBlock::const_iterator II = I->begin(), E = I->end();
+	 II != E; ++II) {
+      // Print the assembly for the instruction.
+      O << "\t";
+      printMachineInstruction(II);
+    }
+  }
+
+  // We didn't modify anything.
+  return false;
+}
+
+
+
+void Printer::printOp(const MachineOperand &MO,
+		      bool elideOffsetKeyword /* = false */) {
+  const MRegisterInfo &RI = *TM.getRegisterInfo();
+  int new_symbol;
+  
+  switch (MO.getType()) {
+  case MachineOperand::MO_VirtualRegister:
+    if (Value *V = MO.getVRegValueOrNull()) {
+      O << "<" << V->getName() << ">";
+      return;
+    }
+    // FALLTHROUGH
+  case MachineOperand::MO_MachineRegister:
+      O << RI.get(MO.getReg()).Name;
+      return;
+
+  case MachineOperand::MO_SignExtendedImmed:
+  case MachineOperand::MO_UnextendedImmed:
+    O << (int)MO.getImmedValue();
+    return;
+  case MachineOperand::MO_MachineBasicBlock: {
+    MachineBasicBlock *MBBOp = MO.getMachineBasicBlock();
+    O << ".LBB" << Mang->getValueName(MBBOp->getParent()->getFunction())
+      << "_" << MBBOp->getNumber () << "\t# "
+      << MBBOp->getBasicBlock ()->getName ();
+    return;
+  }
+  case MachineOperand::MO_PCRelativeDisp:
+    std::cerr << "Shouldn't use addPCDisp() when building PPC MachineInstrs";
+    abort ();
+    return;
+  case MachineOperand::MO_GlobalAddress:
+    if (!elideOffsetKeyword) {
+		if(isa<Function>(MO.getGlobal())) {
+			Stubs.insert(Mang->getValueName(MO.getGlobal()));
+			O << "L" << Mang->getValueName(MO.getGlobal()) << "$stub";
+		} else {
+			O << Mang->getValueName(MO.getGlobal());
+		}
+    }
+    return;
+  case MachineOperand::MO_ExternalSymbol:
+    O << MO.getSymbolName();
+    return;
+  default:
+    O << "<unknown operand type>"; return;    
+  }
+}
+
+#if 0
+static inline
+unsigned int ValidOpcodes(const MachineInstr *MI, unsigned int ArgType[5]) {
+	int i;
+	unsigned int retval = 1;
+	
+	for(i = 0; i<5; i++) {
+		switch(ArgType[i]) {
+			case none:
+				break;
+			case Gpr:
+			case Gpr0:
+				Type::UIntTy
+			case Simm16:
+			case Zimm16:
+			case PCRelimm24:
+			case Imm24:
+			case Imm5:
+			case PCRelimm14:
+			case Imm14:
+			case Imm2:
+			case Crf:
+			case Imm3:
+			case Imm1:
+			case Fpr:
+			case Imm4:
+			case Imm8:
+			case Disimm16:
+			case Spr:
+			case Sgr:
+	};
+		
+		}
+	}
+}
+#endif
+
+/// printMachineInstruction -- Print out a single PPC32 LLVM instruction
+/// MI in Darwin syntax to the current output stream.
+///
+void Printer::printMachineInstruction(const MachineInstr *MI) {
+  unsigned Opcode = MI->getOpcode();
+  const TargetInstrInfo &TII = *TM.getInstrInfo();
+  const TargetInstrDescriptor &Desc = TII.get(Opcode);
+  unsigned int i;
+  
+  unsigned int ArgCount = Desc.TSFlags & PPC32II::ArgCountMask;
+  unsigned int ArgType[5];
+
+
+  ArgType[0] = (Desc.TSFlags>>PPC32II::Arg0TypeShift) & PPC32II::ArgTypeMask;
+  ArgType[1] = (Desc.TSFlags>>PPC32II::Arg1TypeShift) & PPC32II::ArgTypeMask;
+  ArgType[2] = (Desc.TSFlags>>PPC32II::Arg2TypeShift) & PPC32II::ArgTypeMask;
+  ArgType[3] = (Desc.TSFlags>>PPC32II::Arg3TypeShift) & PPC32II::ArgTypeMask;
+  ArgType[4] = (Desc.TSFlags>>PPC32II::Arg4TypeShift) & PPC32II::ArgTypeMask;
+  
+  assert ( ((Desc.TSFlags & PPC32II::VMX) == 0) && "Instruction requires VMX support");
+  assert ( ((Desc.TSFlags & PPC32II::PPC64) == 0) && "Instruction requires 64 bit support");
+  //assert ( ValidOpcodes(MI, ArgType) && "Instruction has invalid inputs");
+  ++EmittedInsts;
+
+  if(Opcode == PPC32::MovePCtoLR) {
+    O << "mflr r0\n";
+    O << "bcl 20,31,L" << CurrentFnName << "$pb\n";
+    O  << "L" << CurrentFnName << "$pb:\n";
+    return;
+  }
+
+  O << TII.getName(MI->getOpcode()) << " ";
+  std::cout << TII.getName(MI->getOpcode()) << " expects " << ArgCount << " args\n";
+
+  if(Opcode == PPC32::LOADLoAddr) {
+    printOp(MI->getOperand(0));
+    O << ", ";
+    printOp(MI->getOperand(1));
+    O << ", lo16(";
+    printOp(MI->getOperand(2));
+    O << "-L" << CurrentFnName << "$pb)\n";
+    return;
+  }
+
+  if(Opcode == PPC32::LOADHiAddr) {
+    printOp(MI->getOperand(0));
+    O << ", ";
+    printOp(MI->getOperand(1));
+    O << ", ha16(" ;
+    printOp(MI->getOperand(2));
+     O << "-L" << CurrentFnName << "$pb)\n";
+    return;
+  }
+  
+  if( (ArgCount == 3) && (ArgType[1] == PPC32II::Disimm16) ) {
+    printOp(MI->getOperand(0));
+    O << ", ";
+    printOp(MI->getOperand(1));
+    O << "(";
+    if((ArgType[2] == PPC32II::Gpr0) && (MI->getOperand(2).getReg() == PPC32::R0)) {
+    	O << "0";
+    } else {
+    	printOp(MI->getOperand(2));
+    }
+    O << ")\n";
+  } else {
+    for(i = 0; i< ArgCount; i++) {
+        if( (ArgType[i] == PPC32II::Gpr0) && ((MI->getOperand(i).getReg()) == PPC32::R0)) {
+            O << "0";
+        } else {
+        	//std::cout << "DEBUG " << (*(TM.getRegisterInfo())).get(MI->getOperand(i).getReg()).Name << "\n";
+            printOp(MI->getOperand(i));
+        }
+        if( ArgCount - 1 == i) {
+            O << "\n";
+        } else {
+            O << ", ";
+        }
+    }
+  }
+  
+  return;  
+}
+
+bool Printer::doInitialization(Module &M) {
+  // Tell gas we are outputting Intel syntax (not AT&T syntax) assembly.
+  //
+  // Bug: gas in `intel_syntax noprefix' mode interprets the symbol `Sp' in an
+  // instruction as a reference to the register named sp, and if you try to
+  // reference a symbol `Sp' (e.g. `mov ECX, OFFSET Sp') then it gets lowercased
+  // before being looked up in the symbol table. This creates spurious
+  // `undefined symbol' errors when linking. Workaround: Do not use `noprefix'
+  // mode, and decorate all register names with percent signs.
+ // O << "\t.intel_syntax\n";
+  Mang = new Mangler(M, true);
+  return false; // success
+}
+
+// SwitchSection - Switch to the specified section of the executable if we are
+// not already in it!
+//
+static void SwitchSection(std::ostream &OS, std::string &CurSection,
+                          const char *NewSection) {
+  if (CurSection != NewSection) {
+    CurSection = NewSection;
+    if (!CurSection.empty())
+      OS << "\t" << NewSection << "\n";
+  }
+}
+
+bool Printer::doFinalization(Module &M) {
+  const TargetData &TD = TM.getTargetData();
+  std::string CurSection;
+
+  // Print out module-level global variables here.
+  for (Module::const_giterator I = M.gbegin(), E = M.gend(); I != E; ++I)
+    if (I->hasInitializer()) {   // External global require no code
+      O << "\n\n";
+      std::string name = Mang->getValueName(I);
+      Constant *C = I->getInitializer();
+      unsigned Size = TD.getTypeSize(C->getType());
+      unsigned Align = TD.getTypeAlignment(C->getType());
+
+      if (C->isNullValue() && 
+          (I->hasLinkOnceLinkage() || I->hasInternalLinkage() ||
+           I->hasWeakLinkage() /* FIXME: Verify correct */)) {
+        SwitchSection(O, CurSection, ".data");
+        if (I->hasInternalLinkage())
+          O << "\t.local " << name << "\n";
+        
+        O << "\t.comm " << name << "," << TD.getTypeSize(C->getType())
+          << "," << (unsigned)TD.getTypeAlignment(C->getType());
+        O << "\t\t# ";
+        WriteAsOperand(O, I, true, true, &M);
+        O << "\n";
+      } else {
+        switch (I->getLinkage()) {
+        case GlobalValue::LinkOnceLinkage:
+        case GlobalValue::WeakLinkage:   // FIXME: Verify correct for weak.
+          // Nonnull linkonce -> weak
+          O << "\t.weak " << name << "\n";
+          SwitchSection(O, CurSection, "");
+          O << "\t.section\t.llvm.linkonce.d." << name << ",\"aw\",@progbits\n";
+          break;
+        
+        case GlobalValue::AppendingLinkage:
+          // FIXME: appending linkage variables should go into a section of
+          // their name or something.  For now, just emit them as external.
+        case GlobalValue::ExternalLinkage:
+          // If external or appending, declare as a global symbol
+          O << "\t.globl " << name << "\n";
+          // FALL THROUGH
+        case GlobalValue::InternalLinkage:
+          if (C->isNullValue())
+            SwitchSection(O, CurSection, ".bss");
+          else
+            SwitchSection(O, CurSection, ".data");
+          break;
+        }
+
+        O << "\t.align " << Align << "\n";
+        O << name << ":\t\t\t\t# ";
+        WriteAsOperand(O, I, true, true, &M);
+        O << " = ";
+        WriteAsOperand(O, C, false, false, &M);
+        O << "\n";
+        emitGlobalConstant(C);
+      }
+    }
+        
+    for(std::set<std::string>::iterator i = Stubs.begin(); i != Stubs.end(); ++i) {
+    	O << ".data\n";     
+		O << ".section __TEXT,__picsymbolstub1,symbol_stubs,pure_instructions,32\n";
+		O << "\t.align 2\n";
+    	O << "L" << *i << "$stub:\n";
+    	O << "\t.indirect_symbol " << *i << "\n";
+    	O << "\tmflr r0\n";
+    	O << "\tbcl 20,31,L0$" << *i << "\n";
+    	O << "L0$" << *i << ":\n";
+    	O << "\tmflr r11\n";
+    	O << "\taddis r11,r11,ha16(L" << *i << "$lazy_ptr-L0$" << *i << ")\n";
+    	O << "\tmtlr r0\n";
+    	O << "\tlwzu r12,lo16(L" << *i << "$lazy_ptr-L0$" << *i << ")(r11)\n";
+    	O << "\tmtctr r12\n";
+    	O << "\tbctr\n";
+    	O << ".data\n";
+		O << ".lazy_symbol_pointer\n";
+		O << "L" << *i << "$lazy_ptr:\n";
+        O << ".indirect_symbol " << *i << "\n";
+        O << ".long dyld_stub_binding_helper\n";
+
+   	}
+
+  delete Mang;
+  return false; // success
+}
+
+} // End llvm namespace