1 files changed, 1103 insertions, 0 deletions
diff --git a/contrib/llvm/lib/CodeGen/ELFWriter.cpp b/contrib/llvm/lib/CodeGen/ELFWriter.cpp
new file mode 100644
index 0000000..0fd1e8e
--- /dev/null
+++ b/contrib/llvm/lib/CodeGen/ELFWriter.cpp
@@ -0,0 +1,1103 @@
+//===-- ELFWriter.cpp - Target-independent ELF Writer code ----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the target-independent ELF writer.  This file writes out
+// the ELF file in the following order:
+//
+//  #1. ELF Header
+//  #2. '.text' section
+//  #3. '.data' section
+//  #4. '.bss' section  (conceptual position in file)
+//  ...
+//  #X. '.shstrtab' section
+//  #Y. Section Table
+//
+// The entries in the section table are laid out as:
+//  #0. Null entry [required]
+//  #1. ".text" entry - the program code
+//  #2. ".data" entry - global variables with initializers.     [ if needed ]
+//  #3. ".bss" entry  - global variables without initializers.  [ if needed ]
+//  ...
+//  #N. ".shstrtab" entry - String table for the section names.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "elfwriter"
+#include "ELF.h"
+#include "ELFWriter.h"
+#include "ELFCodeEmitter.h"
+#include "llvm/Constants.h"
+#include "llvm/Module.h"
+#include "llvm/PassManager.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/CodeGen/BinaryObject.h"
+#include "llvm/CodeGen/MachineCodeEmitter.h"
+#include "llvm/CodeGen/ObjectCodeEmitter.h"
+#include "llvm/CodeGen/MachineCodeEmitter.h"
+#include "llvm/CodeGen/MachineConstantPool.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCSectionELF.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/Target/Mangler.h"
+#include "llvm/Target/TargetAsmInfo.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetELFWriterInfo.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/TargetLoweringObjectFile.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/ADT/SmallString.h"
+using namespace llvm;
+
+char ELFWriter::ID = 0;
+
+//===----------------------------------------------------------------------===//
+//                          ELFWriter Implementation
+//===----------------------------------------------------------------------===//
+
+ELFWriter::ELFWriter(raw_ostream &o, TargetMachine &tm)
+  : MachineFunctionPass(ID), O(o), TM(tm),
+    OutContext(*new MCContext(*TM.getMCAsmInfo(), new TargetAsmInfo(tm))),
+    TLOF(TM.getTargetLowering()->getObjFileLowering()),
+    is64Bit(TM.getTargetData()->getPointerSizeInBits() == 64),
+    isLittleEndian(TM.getTargetData()->isLittleEndian()),
+    ElfHdr(isLittleEndian, is64Bit) {
+
+  MAI = TM.getMCAsmInfo();
+  TEW = TM.getELFWriterInfo();
+
+  // Create the object code emitter object for this target.
+  ElfCE = new ELFCodeEmitter(*this);
+
+  // Inital number of sections
+  NumSections = 0;
+}
+
+ELFWriter::~ELFWriter() {
+  delete ElfCE;
+  delete &OutContext;
+
+  while(!SymbolList.empty()) {
+    delete SymbolList.back(); 
+    SymbolList.pop_back();
+  }
+
+  while(!PrivateSyms.empty()) {
+    delete PrivateSyms.back(); 
+    PrivateSyms.pop_back();
+  }
+
+  while(!SectionList.empty()) {
+    delete SectionList.back(); 
+    SectionList.pop_back();
+  }
+
+  // Release the name mangler object.
+  delete Mang; Mang = 0;
+}
+
+// doInitialization - Emit the file header and all of the global variables for
+// the module to the ELF file.
+bool ELFWriter::doInitialization(Module &M) {
+  // Initialize TargetLoweringObjectFile.
+  const_cast<TargetLoweringObjectFile&>(TLOF).Initialize(OutContext, TM);
+  
+  Mang = new Mangler(OutContext, *TM.getTargetData());
+
+  // ELF Header
+  // ----------
+  // Fields e_shnum e_shstrndx are only known after all section have
+  // been emitted. They locations in the ouput buffer are recorded so
+  // to be patched up later.
+  //
+  // Note
+  // ----
+  // emitWord method behaves differently for ELF32 and ELF64, writing
+  // 4 bytes in the former and 8 in the last for *_off and *_addr elf types
+
+  ElfHdr.emitByte(0x7f); // e_ident[EI_MAG0]
+  ElfHdr.emitByte('E');  // e_ident[EI_MAG1]
+  ElfHdr.emitByte('L');  // e_ident[EI_MAG2]
+  ElfHdr.emitByte('F');  // e_ident[EI_MAG3]
+
+  ElfHdr.emitByte(TEW->getEIClass()); // e_ident[EI_CLASS]
+  ElfHdr.emitByte(TEW->getEIData());  // e_ident[EI_DATA]
+  ElfHdr.emitByte(ELF::EV_CURRENT);   // e_ident[EI_VERSION]
+  ElfHdr.emitAlignment(16);           // e_ident[EI_NIDENT-EI_PAD]
+
+  ElfHdr.emitWord16(ELF::ET_REL);        // e_type
+  ElfHdr.emitWord16(TEW->getEMachine()); // e_machine = target
+  ElfHdr.emitWord32(ELF::EV_CURRENT);    // e_version
+  ElfHdr.emitWord(0);                    // e_entry, no entry point in .o file
+  ElfHdr.emitWord(0);                    // e_phoff, no program header for .o
+  ELFHdr_e_shoff_Offset = ElfHdr.size();
+  ElfHdr.emitWord(0);                    // e_shoff = sec hdr table off in bytes
+  ElfHdr.emitWord32(TEW->getEFlags());   // e_flags = whatever the target wants
+  ElfHdr.emitWord16(TEW->getHdrSize());  // e_ehsize = ELF header size
+  ElfHdr.emitWord16(0);                  // e_phentsize = prog header entry size
+  ElfHdr.emitWord16(0);                  // e_phnum = # prog header entries = 0
+
+  // e_shentsize = Section header entry size
+  ElfHdr.emitWord16(TEW->getSHdrSize());
+
+  // e_shnum     = # of section header ents
+  ELFHdr_e_shnum_Offset = ElfHdr.size();
+  ElfHdr.emitWord16(0); // Placeholder
+
+  // e_shstrndx  = Section # of '.shstrtab'
+  ELFHdr_e_shstrndx_Offset = ElfHdr.size();
+  ElfHdr.emitWord16(0); // Placeholder
+
+  // Add the null section, which is required to be first in the file.
+  getNullSection();
+
+  // The first entry in the symtab is the null symbol and the second
+  // is a local symbol containing the module/file name
+  SymbolList.push_back(new ELFSym());
+  SymbolList.push_back(ELFSym::getFileSym());
+
+  return false;
+}
+
+// AddPendingGlobalSymbol - Add a global to be processed and to
+// the global symbol lookup, use a zero index because the table
+// index will be determined later.
+void ELFWriter::AddPendingGlobalSymbol(const GlobalValue *GV, 
+                                       bool AddToLookup /* = false */) {
+  PendingGlobals.insert(GV);
+  if (AddToLookup) 
+    GblSymLookup[GV] = 0;
+}
+
+// AddPendingExternalSymbol - Add the external to be processed
+// and to the external symbol lookup, use a zero index because
+// the symbol table index will be determined later.
+void ELFWriter::AddPendingExternalSymbol(const char *External) {
+  PendingExternals.insert(External);
+  ExtSymLookup[External] = 0;
+}
+
+ELFSection &ELFWriter::getDataSection() {
+  const MCSectionELF *Data = (const MCSectionELF *)TLOF.getDataSection();
+  return getSection(Data->getSectionName(), Data->getType(), 
+                    Data->getFlags(), 4);
+}
+
+ELFSection &ELFWriter::getBSSSection() {
+  const MCSectionELF *BSS = (const MCSectionELF *)TLOF.getBSSSection();
+  return getSection(BSS->getSectionName(), BSS->getType(), BSS->getFlags(), 4);
+}
+
+// getCtorSection - Get the static constructor section
+ELFSection &ELFWriter::getCtorSection() {
+  const MCSectionELF *Ctor = (const MCSectionELF *)TLOF.getStaticCtorSection();
+  return getSection(Ctor->getSectionName(), Ctor->getType(), Ctor->getFlags()); 
+}
+
+// getDtorSection - Get the static destructor section
+ELFSection &ELFWriter::getDtorSection() {
+  const MCSectionELF *Dtor = (const MCSectionELF *)TLOF.getStaticDtorSection();
+  return getSection(Dtor->getSectionName(), Dtor->getType(), Dtor->getFlags());
+}
+
+// getTextSection - Get the text section for the specified function
+ELFSection &ELFWriter::getTextSection(const Function *F) {
+  const MCSectionELF *Text = 
+    (const MCSectionELF *)TLOF.SectionForGlobal(F, Mang, TM);
+  return getSection(Text->getSectionName(), Text->getType(), Text->getFlags());
+}
+
+// getJumpTableSection - Get a read only section for constants when 
+// emitting jump tables. TODO: add PIC support
+ELFSection &ELFWriter::getJumpTableSection() {
+  const MCSectionELF *JT = 
+    (const MCSectionELF *)TLOF.getSectionForConstant(SectionKind::getReadOnly());
+  return getSection(JT->getSectionName(), JT->getType(), JT->getFlags(),
+                    TM.getTargetData()->getPointerABIAlignment());
+}
+
+// getConstantPoolSection - Get a constant pool section based on the machine 
+// constant pool entry type and relocation info.
+ELFSection &ELFWriter::getConstantPoolSection(MachineConstantPoolEntry &CPE) {
+  SectionKind Kind;
+  switch (CPE.getRelocationInfo()) {
+  default: llvm_unreachable("Unknown section kind");
+  case 2: Kind = SectionKind::getReadOnlyWithRel(); break;
+  case 1:
+    Kind = SectionKind::getReadOnlyWithRelLocal();
+    break;
+  case 0:
+    switch (TM.getTargetData()->getTypeAllocSize(CPE.getType())) {
+    case 4:  Kind = SectionKind::getMergeableConst4(); break;
+    case 8:  Kind = SectionKind::getMergeableConst8(); break;
+    case 16: Kind = SectionKind::getMergeableConst16(); break;
+    default: Kind = SectionKind::getMergeableConst(); break;
+    }
+  }
+
+  const MCSectionELF *CPSect = 
+    (const MCSectionELF *)TLOF.getSectionForConstant(Kind);
+  return getSection(CPSect->getSectionName(), CPSect->getType(), 
+                    CPSect->getFlags(), CPE.getAlignment());
+}
+
+// getRelocSection - Return the relocation section of section 'S'. 'RelA' 
+// is true if the relocation section contains entries with addends.
+ELFSection &ELFWriter::getRelocSection(ELFSection &S) {
+  unsigned SectionType = TEW->hasRelocationAddend() ?
+                ELF::SHT_RELA : ELF::SHT_REL;
+
+  std::string SectionName(".rel");
+  if (TEW->hasRelocationAddend())
+    SectionName.append("a");
+  SectionName.append(S.getName());
+
+  return getSection(SectionName, SectionType, 0, TEW->getPrefELFAlignment());
+}
+
+// getGlobalELFVisibility - Returns the ELF specific visibility type
+unsigned ELFWriter::getGlobalELFVisibility(const GlobalValue *GV) {
+  switch (GV->getVisibility()) {
+  default:
+    llvm_unreachable("unknown visibility type");
+  case GlobalValue::DefaultVisibility:
+    return ELF::STV_DEFAULT;
+  case GlobalValue::HiddenVisibility:
+    return ELF::STV_HIDDEN;
+  case GlobalValue::ProtectedVisibility:
+    return ELF::STV_PROTECTED;
+  }
+  return 0;
+}
+
+// getGlobalELFBinding - Returns the ELF specific binding type
+unsigned ELFWriter::getGlobalELFBinding(const GlobalValue *GV) {
+  if (GV->hasInternalLinkage())
+    return ELF::STB_LOCAL;
+
+  if (GV->isWeakForLinker() && !GV->hasCommonLinkage())
+    return ELF::STB_WEAK;
+
+  return ELF::STB_GLOBAL;
+}
+
+// getGlobalELFType - Returns the ELF specific type for a global
+unsigned ELFWriter::getGlobalELFType(const GlobalValue *GV) {
+  if (GV->isDeclaration())
+    return ELF::STT_NOTYPE;
+
+  if (isa<Function>(GV))
+    return ELF::STT_FUNC;
+
+  return ELF::STT_OBJECT;
+}
+
+// IsELFUndefSym - True if the global value must be marked as a symbol
+// which points to a SHN_UNDEF section. This means that the symbol has
+// no definition on the module.
+static bool IsELFUndefSym(const GlobalValue *GV) {
+  return GV->isDeclaration() || (isa<Function>(GV));
+}
+
+// AddToSymbolList - Update the symbol lookup and If the symbol is 
+// private add it to PrivateSyms list, otherwise to SymbolList. 
+void ELFWriter::AddToSymbolList(ELFSym *GblSym) {
+  assert(GblSym->isGlobalValue() && "Symbol must be a global value");
+
+  const GlobalValue *GV = GblSym->getGlobalValue(); 
+  if (GV->hasPrivateLinkage()) {
+    // For a private symbols, keep track of the index inside 
+    // the private list since it will never go to the symbol 
+    // table and won't be patched up later.
+    PrivateSyms.push_back(GblSym);
+    GblSymLookup[GV] = PrivateSyms.size()-1;
+  } else {
+    // Non private symbol are left with zero indices until 
+    // they are patched up during the symbol table emition 
+    // (where the indicies are created).
+    SymbolList.push_back(GblSym);
+    GblSymLookup[GV] = 0;
+  }
+}
+
+/// HasCommonSymbols - True if this section holds common symbols, this is
+/// indicated on the ELF object file by a symbol with SHN_COMMON section
+/// header index.
+static bool HasCommonSymbols(const MCSectionELF &S) {
+  // FIXME: this is wrong, a common symbol can be in .data for example.
+  if (StringRef(S.getSectionName()).startswith(".gnu.linkonce."))
+    return true;
+
+  return false;
+}
+
+
+// EmitGlobal - Choose the right section for global and emit it
+void ELFWriter::EmitGlobal(const GlobalValue *GV) {
+
+  // Check if the referenced symbol is already emitted
+  if (GblSymLookup.find(GV) != GblSymLookup.end())
+    return;
+
+  // Handle ELF Bind, Visibility and Type for the current symbol
+  unsigned SymBind = getGlobalELFBinding(GV);
+  unsigned SymType = getGlobalELFType(GV);
+  bool IsUndefSym = IsELFUndefSym(GV);
+
+  ELFSym *GblSym = IsUndefSym ? ELFSym::getUndefGV(GV, SymBind)
+    : ELFSym::getGV(GV, SymBind, SymType, getGlobalELFVisibility(GV));
+
+  if (!IsUndefSym) {
+    assert(isa<GlobalVariable>(GV) && "GV not a global variable!");
+    const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
+
+    // Handle special llvm globals
+    if (EmitSpecialLLVMGlobal(GVar))
+      return;
+
+    // Get the ELF section where this global belongs from TLOF
+    const MCSectionELF *S = 
+      (const MCSectionELF *)TLOF.SectionForGlobal(GV, Mang, TM);
+    ELFSection &ES = 
+      getSection(S->getSectionName(), S->getType(), S->getFlags());
+    SectionKind Kind = S->getKind();
+
+    // The symbol align should update the section alignment if needed
+    const TargetData *TD = TM.getTargetData();
+    unsigned Align = TD->getPreferredAlignment(GVar);
+    unsigned Size = TD->getTypeAllocSize(GVar->getInitializer()->getType());
+    GblSym->Size = Size;
+
+    if (HasCommonSymbols(*S)) { // Symbol must go to a common section
+      GblSym->SectionIdx = ELF::SHN_COMMON;
+
+      // A new linkonce section is created for each global in the
+      // common section, the default alignment is 1 and the symbol
+      // value contains its alignment.
+      ES.Align = 1;
+      GblSym->Value = Align;
+
+    } else if (Kind.isBSS() || Kind.isThreadBSS()) { // Symbol goes to BSS.
+      GblSym->SectionIdx = ES.SectionIdx;
+
+      // Update the size with alignment and the next object can
+      // start in the right offset in the section
+      if (Align) ES.Size = (ES.Size + Align-1) & ~(Align-1);
+      ES.Align = std::max(ES.Align, Align);
+
+      // GblSym->Value should contain the virtual offset inside the section.
+      // Virtual because the BSS space is not allocated on ELF objects
+      GblSym->Value = ES.Size;
+      ES.Size += Size;
+
+    } else { // The symbol must go to some kind of data section
+      GblSym->SectionIdx = ES.SectionIdx;
+
+      // GblSym->Value should contain the symbol offset inside the section,
+      // and all symbols should start on their required alignment boundary
+      ES.Align = std::max(ES.Align, Align);
+      ES.emitAlignment(Align);
+      GblSym->Value = ES.size();
+
+      // Emit the global to the data section 'ES'
+      EmitGlobalConstant(GVar->getInitializer(), ES);
+    }
+  }
+
+  AddToSymbolList(GblSym);
+}
+
+void ELFWriter::EmitGlobalConstantStruct(const ConstantStruct *CVS,
+                                         ELFSection &GblS) {
+
+  // Print the fields in successive locations. Pad to align if needed!
+  const TargetData *TD = TM.getTargetData();
+  unsigned Size = TD->getTypeAllocSize(CVS->getType());
+  const StructLayout *cvsLayout = TD->getStructLayout(CVS->getType());
+  uint64_t sizeSoFar = 0;
+  for (unsigned i = 0, e = CVS->getNumOperands(); i != e; ++i) {
+    const Constant* field = CVS->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 : cvsLayout->getElementOffset(i+1))
+                        - cvsLayout->getElementOffset(i)) - fieldSize;
+    sizeSoFar += fieldSize + padSize;
+
+    // Now print the actual field value.
+    EmitGlobalConstant(field, GblS);
+
+    // 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.
+    GblS.emitZeros(padSize);
+  }
+  assert(sizeSoFar == cvsLayout->getSizeInBytes() &&
+         "Layout of constant struct may be incorrect!");
+}
+
+void ELFWriter::EmitGlobalConstant(const Constant *CV, ELFSection &GblS) {
+  const TargetData *TD = TM.getTargetData();
+  unsigned Size = TD->getTypeAllocSize(CV->getType());
+
+  if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV)) {
+    for (unsigned i = 0, e = CVA->getNumOperands(); i != e; ++i)
+      EmitGlobalConstant(CVA->getOperand(i), GblS);
+    return;
+  } else if (isa<ConstantAggregateZero>(CV)) {
+    GblS.emitZeros(Size);
+    return;
+  } else if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV)) {
+    EmitGlobalConstantStruct(CVS, GblS);
+    return;
+  } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV)) {
+    APInt Val = CFP->getValueAPF().bitcastToAPInt();
+    if (CFP->getType()->isDoubleTy())
+      GblS.emitWord64(Val.getZExtValue());
+    else if (CFP->getType()->isFloatTy())
+      GblS.emitWord32(Val.getZExtValue());
+    else if (CFP->getType()->isX86_FP80Ty()) {
+      unsigned PadSize = TD->getTypeAllocSize(CFP->getType())-
+                         TD->getTypeStoreSize(CFP->getType());
+      GblS.emitWordFP80(Val.getRawData(), PadSize);
+    } else if (CFP->getType()->isPPC_FP128Ty())
+      llvm_unreachable("PPC_FP128Ty global emission not implemented");
+    return;
+  } else if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
+    if (Size == 1)
+      GblS.emitByte(CI->getZExtValue());
+    else if (Size == 2) 
+      GblS.emitWord16(CI->getZExtValue());
+    else if (Size == 4)
+      GblS.emitWord32(CI->getZExtValue());
+    else 
+      EmitGlobalConstantLargeInt(CI, GblS);
+    return;
+  } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CV)) {
+    const VectorType *PTy = CP->getType();
+    for (unsigned I = 0, E = PTy->getNumElements(); I < E; ++I)
+      EmitGlobalConstant(CP->getOperand(I), GblS);
+    return;
+  } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV)) {
+    // Resolve a constant expression which returns a (Constant, Offset)
+    // pair. If 'Res.first' is a GlobalValue, emit a relocation with 
+    // the offset 'Res.second', otherwise emit a global constant like
+    // it is always done for not contant expression types.
+    CstExprResTy Res = ResolveConstantExpr(CE);
+    const Constant *Op = Res.first;
+
+    if (isa<GlobalValue>(Op))
+      EmitGlobalDataRelocation(cast<const GlobalValue>(Op), 
+                               TD->getTypeAllocSize(Op->getType()), 
+                               GblS, Res.second);
+    else
+      EmitGlobalConstant(Op, GblS);
+
+    return;
+  } else if (CV->getType()->getTypeID() == Type::PointerTyID) {
+    // Fill the data entry with zeros or emit a relocation entry
+    if (isa<ConstantPointerNull>(CV))
+      GblS.emitZeros(Size);
+    else 
+      EmitGlobalDataRelocation(cast<const GlobalValue>(CV), 
+                               Size, GblS);
+    return;
+  } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV)) {
+    // This is a constant address for a global variable or function and
+    // therefore must be referenced using a relocation entry.
+    EmitGlobalDataRelocation(GV, Size, GblS);
+    return;
+  }
+
+  std::string msg;
+  raw_string_ostream ErrorMsg(msg);
+  ErrorMsg << "Constant unimp for type: " << *CV->getType();
+  report_fatal_error(ErrorMsg.str());
+}
+
+// ResolveConstantExpr - Resolve the constant expression until it stop
+// yielding other constant expressions.
+CstExprResTy ELFWriter::ResolveConstantExpr(const Constant *CV) {
+  const TargetData *TD = TM.getTargetData();
+  
+  // There ins't constant expression inside others anymore
+  if (!isa<ConstantExpr>(CV))
+    return std::make_pair(CV, 0);
+
+  const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV);
+  switch (CE->getOpcode()) {
+  case Instruction::BitCast:
+    return ResolveConstantExpr(CE->getOperand(0));
+  
+  case Instruction::GetElementPtr: {
+    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());
+    return std::make_pair(ptrVal, Offset);
+  }
+  case Instruction::IntToPtr: {
+    Constant *Op = CE->getOperand(0);
+    Op = ConstantExpr::getIntegerCast(Op, TD->getIntPtrType(CV->getContext()),
+                                      false/*ZExt*/);
+    return ResolveConstantExpr(Op);
+  }
+  case Instruction::PtrToInt: {
+    Constant *Op = CE->getOperand(0);
+    const Type *Ty = CE->getType();
+
+    // We can emit the pointer value into this slot if the slot is an
+    // integer slot greater or equal to the size of the pointer.
+    if (TD->getTypeAllocSize(Ty) == TD->getTypeAllocSize(Op->getType()))
+      return ResolveConstantExpr(Op);
+
+    llvm_unreachable("Integer size less then pointer size");
+  }
+  case Instruction::Add:
+  case Instruction::Sub: {
+    // Only handle cases where there's a constant expression with GlobalValue
+    // as first operand and ConstantInt as second, which are the cases we can
+    // solve direclty using a relocation entry. GlobalValue=Op0, CstInt=Op1
+    // 1)  Instruction::Add  => (global) + CstInt
+    // 2)  Instruction::Sub  => (global) + -CstInt
+    const Constant *Op0 = CE->getOperand(0); 
+    const Constant *Op1 = CE->getOperand(1); 
+    assert(isa<ConstantInt>(Op1) && "Op1 must be a ConstantInt");
+
+    CstExprResTy Res = ResolveConstantExpr(Op0);
+    assert(isa<GlobalValue>(Res.first) && "Op0 must be a GlobalValue");
+
+    const APInt &RHS = cast<ConstantInt>(Op1)->getValue();
+    switch (CE->getOpcode()) {
+    case Instruction::Add: 
+      return std::make_pair(Res.first, RHS.getSExtValue());
+    case Instruction::Sub:
+      return std::make_pair(Res.first, (-RHS).getSExtValue());
+    }
+  }
+  }
+
+  report_fatal_error(CE->getOpcodeName() +
+                     StringRef(": Unsupported ConstantExpr type"));
+
+  return std::make_pair(CV, 0); // silence warning
+}
+
+void ELFWriter::EmitGlobalDataRelocation(const GlobalValue *GV, unsigned Size,
+                                         ELFSection &GblS, int64_t Offset) {
+  // Create the relocation entry for the global value
+  MachineRelocation MR =
+    MachineRelocation::getGV(GblS.getCurrentPCOffset(),
+                             TEW->getAbsoluteLabelMachineRelTy(),
+                             const_cast<GlobalValue*>(GV),
+                             Offset);
+
+  // Fill the data entry with zeros
+  GblS.emitZeros(Size);
+
+  // Add the relocation entry for the current data section
+  GblS.addRelocation(MR);
+}
+
+void ELFWriter::EmitGlobalConstantLargeInt(const ConstantInt *CI, 
+                                           ELFSection &S) {
+  const TargetData *TD = TM.getTargetData();
+  unsigned BitWidth = CI->getBitWidth();
+  assert(isPowerOf2_32(BitWidth) &&
+         "Non-power-of-2-sized integers not handled!");
+
+  const uint64_t *RawData = CI->getValue().getRawData();
+  uint64_t Val = 0;
+  for (unsigned i = 0, e = BitWidth / 64; i != e; ++i) {
+    Val = (TD->isBigEndian()) ? RawData[e - i - 1] : RawData[i];
+    S.emitWord64(Val);
+  }
+}
+
+/// 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 ELFWriter::EmitSpecialLLVMGlobal(const GlobalVariable *GV) {
+  if (GV->getName() == "llvm.used")
+    llvm_unreachable("not implemented yet");
+
+  // 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 = TD->getPointerPrefAlignment();
+  if (GV->getName() == "llvm.global_ctors") {
+    ELFSection &Ctor = getCtorSection();
+    Ctor.emitAlignment(Align);
+    EmitXXStructorList(GV->getInitializer(), Ctor);
+    return true;
+  } 
+  
+  if (GV->getName() == "llvm.global_dtors") {
+    ELFSection &Dtor = getDtorSection();
+    Dtor.emitAlignment(Align);
+    EmitXXStructorList(GV->getInitializer(), Dtor);
+    return true;
+  }
+  
+  return false;
+}
+
+/// EmitXXStructorList - Emit the ctor or dtor list.  This just emits out the 
+/// function pointers, ignoring the init priority.
+void ELFWriter::EmitXXStructorList(Constant *List, ELFSection &Xtor) {
+  // 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), Xtor);
+    }
+}
+
+bool ELFWriter::runOnMachineFunction(MachineFunction &MF) {
+  // Nothing to do here, this is all done through the ElfCE object above.
+  return false;
+}
+
+/// doFinalization - Now that the module has been completely processed, emit
+/// the ELF file to 'O'.
+bool ELFWriter::doFinalization(Module &M) {
+  // Emit .data section placeholder
+  getDataSection();
+
+  // Emit .bss section placeholder
+  getBSSSection();
+
+  // Build and emit data, bss and "common" sections.
+  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
+       I != E; ++I)
+    EmitGlobal(I);
+
+  // Emit all pending globals
+  for (PendingGblsIter I = PendingGlobals.begin(), E = PendingGlobals.end();
+       I != E; ++I)
+    EmitGlobal(*I);
+
+  // Emit all pending externals
+  for (PendingExtsIter I = PendingExternals.begin(), E = PendingExternals.end();
+       I != E; ++I)
+    SymbolList.push_back(ELFSym::getExtSym(*I));
+
+  // Emit a symbol for each section created until now, skip null section
+  for (unsigned i = 1, e = SectionList.size(); i < e; ++i) {
+    ELFSection &ES = *SectionList[i];
+    ELFSym *SectionSym = ELFSym::getSectionSym();
+    SectionSym->SectionIdx = ES.SectionIdx;
+    SymbolList.push_back(SectionSym);
+    ES.Sym = SymbolList.back();
+  }
+
+  // Emit string table
+  EmitStringTable(M.getModuleIdentifier());
+
+  // Emit the symbol table now, if non-empty.
+  EmitSymbolTable();
+
+  // Emit the relocation sections.
+  EmitRelocations();
+
+  // Emit the sections string table.
+  EmitSectionTableStringTable();
+
+  // Dump the sections and section table to the .o file.
+  OutputSectionsAndSectionTable();
+
+  return false;
+}
+
+// RelocateField - Patch relocatable field with 'Offset' in 'BO'
+// using a 'Value' of known 'Size'
+void ELFWriter::RelocateField(BinaryObject &BO, uint32_t Offset,
+                              int64_t Value, unsigned Size) {
+  if (Size == 32)
+    BO.fixWord32(Value, Offset);
+  else if (Size == 64)
+    BO.fixWord64(Value, Offset);
+  else
+    llvm_unreachable("don't know howto patch relocatable field");
+}
+
+/// EmitRelocations - Emit relocations
+void ELFWriter::EmitRelocations() {
+
+  // True if the target uses the relocation entry to hold the addend,
+  // otherwise the addend is written directly to the relocatable field.
+  bool HasRelA = TEW->hasRelocationAddend();
+
+  // Create Relocation sections for each section which needs it.
+  for (unsigned i=0, e=SectionList.size(); i != e; ++i) {
+    ELFSection &S = *SectionList[i];
+
+    // This section does not have relocations
+    if (!S.hasRelocations()) continue;
+    ELFSection &RelSec = getRelocSection(S);
+
+    // 'Link' - Section hdr idx of the associated symbol table
+    // 'Info' - Section hdr idx of the section to which the relocation applies
+    ELFSection &SymTab = getSymbolTableSection();
+    RelSec.Link = SymTab.SectionIdx;
+    RelSec.Info = S.SectionIdx;
+    RelSec.EntSize = TEW->getRelocationEntrySize();
+
+    // Get the relocations from Section
+    std::vector<MachineRelocation> Relos = S.getRelocations();
+    for (std::vector<MachineRelocation>::iterator MRI = Relos.begin(),
+         MRE = Relos.end(); MRI != MRE; ++MRI) {
+      MachineRelocation &MR = *MRI;
+
+      // Relocatable field offset from the section start
+      unsigned RelOffset = MR.getMachineCodeOffset();
+
+      // Symbol index in the symbol table
+      unsigned SymIdx = 0;
+
+      // Target specific relocation field type and size
+      unsigned RelType = TEW->getRelocationType(MR.getRelocationType());
+      unsigned RelTySize = TEW->getRelocationTySize(RelType);
+      int64_t Addend = 0;
+
+      // There are several machine relocations types, and each one of
+      // them needs a different approach to retrieve the symbol table index.
+      if (MR.isGlobalValue()) {
+        const GlobalValue *G = MR.getGlobalValue();
+        int64_t GlobalOffset = MR.getConstantVal();
+        SymIdx = GblSymLookup[G];
+        if (G->hasPrivateLinkage()) {
+          // If the target uses a section offset in the relocation:
+          // SymIdx + Addend = section sym for global + section offset
+          unsigned SectionIdx = PrivateSyms[SymIdx]->SectionIdx;
+          Addend = PrivateSyms[SymIdx]->Value + GlobalOffset;
+          SymIdx = SectionList[SectionIdx]->getSymbolTableIndex();
+        } else {
+          Addend = TEW->getDefaultAddendForRelTy(RelType, GlobalOffset);
+        }
+      } else if (MR.isExternalSymbol()) {
+        const char *ExtSym = MR.getExternalSymbol();
+        SymIdx = ExtSymLookup[ExtSym];
+        Addend = TEW->getDefaultAddendForRelTy(RelType);
+      } else {
+        // Get the symbol index for the section symbol
+        unsigned SectionIdx = MR.getConstantVal();
+        SymIdx = SectionList[SectionIdx]->getSymbolTableIndex();
+
+        // The symbol offset inside the section
+        int64_t SymOffset = (int64_t)MR.getResultPointer();
+
+        // For pc relative relocations where symbols are defined in the same
+        // section they are referenced, ignore the relocation entry and patch
+        // the relocatable field with the symbol offset directly.
+        if (S.SectionIdx == SectionIdx && TEW->isPCRelativeRel(RelType)) {
+          int64_t Value = TEW->computeRelocation(SymOffset, RelOffset, RelType);
+          RelocateField(S, RelOffset, Value, RelTySize);
+          continue;
+        }
+
+        Addend = TEW->getDefaultAddendForRelTy(RelType, SymOffset);
+      }
+
+      // The target without addend on the relocation symbol must be
+      // patched in the relocation place itself to contain the addend
+      // otherwise write zeros to make sure there is no garbage there
+      RelocateField(S, RelOffset, HasRelA ? 0 : Addend, RelTySize);
+
+      // Get the relocation entry and emit to the relocation section
+      ELFRelocation Rel(RelOffset, SymIdx, RelType, HasRelA, Addend);
+      EmitRelocation(RelSec, Rel, HasRelA);
+    }
+  }
+}
+
+/// EmitRelocation - Write relocation 'Rel' to the relocation section 'Rel'
+void ELFWriter::EmitRelocation(BinaryObject &RelSec, ELFRelocation &Rel,
+                               bool HasRelA) {
+  RelSec.emitWord(Rel.getOffset());
+  RelSec.emitWord(Rel.getInfo(is64Bit));
+  if (HasRelA)
+    RelSec.emitWord(Rel.getAddend());
+}
+
+/// EmitSymbol - Write symbol 'Sym' to the symbol table 'SymbolTable'
+void ELFWriter::EmitSymbol(BinaryObject &SymbolTable, ELFSym &Sym) {
+  if (is64Bit) {
+    SymbolTable.emitWord32(Sym.NameIdx);
+    SymbolTable.emitByte(Sym.Info);
+    SymbolTable.emitByte(Sym.Other);
+    SymbolTable.emitWord16(Sym.SectionIdx);
+    SymbolTable.emitWord64(Sym.Value);
+    SymbolTable.emitWord64(Sym.Size);
+  } else {
+    SymbolTable.emitWord32(Sym.NameIdx);
+    SymbolTable.emitWord32(Sym.Value);
+    SymbolTable.emitWord32(Sym.Size);
+    SymbolTable.emitByte(Sym.Info);
+    SymbolTable.emitByte(Sym.Other);
+    SymbolTable.emitWord16(Sym.SectionIdx);
+  }
+}
+
+/// EmitSectionHeader - Write section 'Section' header in 'SHdrTab'
+/// Section Header Table
+void ELFWriter::EmitSectionHeader(BinaryObject &SHdrTab,
+                                  const ELFSection &SHdr) {
+  SHdrTab.emitWord32(SHdr.NameIdx);
+  SHdrTab.emitWord32(SHdr.Type);
+  if (is64Bit) {
+    SHdrTab.emitWord64(SHdr.Flags);
+    SHdrTab.emitWord(SHdr.Addr);
+    SHdrTab.emitWord(SHdr.Offset);
+    SHdrTab.emitWord64(SHdr.Size);
+    SHdrTab.emitWord32(SHdr.Link);
+    SHdrTab.emitWord32(SHdr.Info);
+    SHdrTab.emitWord64(SHdr.Align);
+    SHdrTab.emitWord64(SHdr.EntSize);
+  } else {
+    SHdrTab.emitWord32(SHdr.Flags);
+    SHdrTab.emitWord(SHdr.Addr);
+    SHdrTab.emitWord(SHdr.Offset);
+    SHdrTab.emitWord32(SHdr.Size);
+    SHdrTab.emitWord32(SHdr.Link);
+    SHdrTab.emitWord32(SHdr.Info);
+    SHdrTab.emitWord32(SHdr.Align);
+    SHdrTab.emitWord32(SHdr.EntSize);
+  }
+}
+
+/// EmitStringTable - If the current symbol table is non-empty, emit the string
+/// table for it
+void ELFWriter::EmitStringTable(const std::string &ModuleName) {
+  if (!SymbolList.size()) return;  // Empty symbol table.
+  ELFSection &StrTab = getStringTableSection();
+
+  // Set the zero'th symbol to a null byte, as required.
+  StrTab.emitByte(0);
+
+  // Walk on the symbol list and write symbol names into the string table.
+  unsigned Index = 1;
+  for (ELFSymIter I=SymbolList.begin(), E=SymbolList.end(); I != E; ++I) {
+    ELFSym &Sym = *(*I);
+
+    std::string Name;
+    if (Sym.isGlobalValue()) {
+      SmallString<40> NameStr;
+      Mang->getNameWithPrefix(NameStr, Sym.getGlobalValue(), false);
+      Name.append(NameStr.begin(), NameStr.end());
+    } else if (Sym.isExternalSym())
+      Name.append(Sym.getExternalSymbol());
+    else if (Sym.isFileType())
+      Name.append(ModuleName);
+
+    if (Name.empty()) {
+      Sym.NameIdx = 0;
+    } else {
+      Sym.NameIdx = Index;
+      StrTab.emitString(Name);
+
+      // Keep track of the number of bytes emitted to this section.
+      Index += Name.size()+1;
+    }
+  }
+  assert(Index == StrTab.size());
+  StrTab.Size = Index;
+}
+
+// SortSymbols - On the symbol table local symbols must come before
+// all other symbols with non-local bindings. The return value is
+// the position of the first non local symbol.
+unsigned ELFWriter::SortSymbols() {
+  unsigned FirstNonLocalSymbol;
+  std::vector<ELFSym*> LocalSyms, OtherSyms;
+
+  for (ELFSymIter I=SymbolList.begin(), E=SymbolList.end(); I != E; ++I) {
+    if ((*I)->isLocalBind())
+      LocalSyms.push_back(*I);
+    else
+      OtherSyms.push_back(*I);
+  }
+  SymbolList.clear();
+  FirstNonLocalSymbol = LocalSyms.size();
+
+  for (unsigned i = 0; i < FirstNonLocalSymbol; ++i)
+    SymbolList.push_back(LocalSyms[i]);
+
+  for (ELFSymIter I=OtherSyms.begin(), E=OtherSyms.end(); I != E; ++I)
+    SymbolList.push_back(*I);
+
+  LocalSyms.clear();
+  OtherSyms.clear();
+
+  return FirstNonLocalSymbol;
+}
+
+/// EmitSymbolTable - Emit the symbol table itself.
+void ELFWriter::EmitSymbolTable() {
+  if (!SymbolList.size()) return;  // Empty symbol table.
+
+  // Now that we have emitted the string table and know the offset into the
+  // string table of each symbol, emit the symbol table itself.
+  ELFSection &SymTab = getSymbolTableSection();
+  SymTab.Align = TEW->getPrefELFAlignment();
+
+  // Section Index of .strtab.
+  SymTab.Link = getStringTableSection().SectionIdx;
+
+  // Size of each symtab entry.
+  SymTab.EntSize = TEW->getSymTabEntrySize();
+
+  // Reorder the symbol table with local symbols first!
+  unsigned FirstNonLocalSymbol = SortSymbols();
+
+  // Emit all the symbols to the symbol table.
+  for (unsigned i = 0, e = SymbolList.size(); i < e; ++i) {
+    ELFSym &Sym = *SymbolList[i];
+
+    // Emit symbol to the symbol table
+    EmitSymbol(SymTab, Sym);
+
+    // Record the symbol table index for each symbol
+    if (Sym.isGlobalValue())
+      GblSymLookup[Sym.getGlobalValue()] = i;
+    else if (Sym.isExternalSym())
+      ExtSymLookup[Sym.getExternalSymbol()] = i;
+
+    // Keep track on the symbol index into the symbol table
+    Sym.SymTabIdx = i;
+  }
+
+  // One greater than the symbol table index of the last local symbol
+  SymTab.Info = FirstNonLocalSymbol;
+  SymTab.Size = SymTab.size();
+}
+
+/// EmitSectionTableStringTable - This method adds and emits a section for the
+/// ELF Section Table string table: the string table that holds all of the
+/// section names.
+void ELFWriter::EmitSectionTableStringTable() {
+  // First step: add the section for the string table to the list of sections:
+  ELFSection &SHStrTab = getSectionHeaderStringTableSection();
+
+  // Now that we know which section number is the .shstrtab section, update the
+  // e_shstrndx entry in the ELF header.
+  ElfHdr.fixWord16(SHStrTab.SectionIdx, ELFHdr_e_shstrndx_Offset);
+
+  // Set the NameIdx of each section in the string table and emit the bytes for
+  // the string table.
+  unsigned Index = 0;
+
+  for (ELFSectionIter I=SectionList.begin(), E=SectionList.end(); I != E; ++I) {
+    ELFSection &S = *(*I);
+    // Set the index into the table.  Note if we have lots of entries with
+    // common suffixes, we could memoize them here if we cared.
+    S.NameIdx = Index;
+    SHStrTab.emitString(S.getName());
+
+    // Keep track of the number of bytes emitted to this section.
+    Index += S.getName().size()+1;
+  }
+
+  // Set the size of .shstrtab now that we know what it is.
+  assert(Index == SHStrTab.size());
+  SHStrTab.Size = Index;
+}
+
+/// OutputSectionsAndSectionTable - Now that we have constructed the file header
+/// and all of the sections, emit these to the ostream destination and emit the
+/// SectionTable.
+void ELFWriter::OutputSectionsAndSectionTable() {
+  // Pass #1: Compute the file offset for each section.
+  size_t FileOff = ElfHdr.size();   // File header first.
+
+  // Adjust alignment of all section if needed, skip the null section.
+  for (unsigned i=1, e=SectionList.size(); i < e; ++i) {
+    ELFSection &ES = *SectionList[i];
+    if (!ES.size()) {
+      ES.Offset = FileOff;
+      continue;
+    }
+
+    // Update Section size
+    if (!ES.Size)
+      ES.Size = ES.size();
+
+    // Align FileOff to whatever the alignment restrictions of the section are.
+    if (ES.Align)
+      FileOff = (FileOff+ES.Align-1) & ~(ES.Align-1);
+
+    ES.Offset = FileOff;
+    FileOff += ES.Size;
+  }
+
+  // Align Section Header.
+  unsigned TableAlign = TEW->getPrefELFAlignment();
+  FileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
+
+  // Now that we know where all of the sections will be emitted, set the e_shnum
+  // entry in the ELF header.
+  ElfHdr.fixWord16(NumSections, ELFHdr_e_shnum_Offset);
+
+  // Now that we know the offset in the file of the section table, update the
+  // e_shoff address in the ELF header.
+  ElfHdr.fixWord(FileOff, ELFHdr_e_shoff_Offset);
+
+  // Now that we know all of the data in the file header, emit it and all of the
+  // sections!
+  O.write((char *)&ElfHdr.getData()[0], ElfHdr.size());
+  FileOff = ElfHdr.size();
+
+  // Section Header Table blob
+  BinaryObject SHdrTable(isLittleEndian, is64Bit);
+
+  // Emit all of sections to the file and build the section header table.
+  for (ELFSectionIter I=SectionList.begin(), E=SectionList.end(); I != E; ++I) {
+    ELFSection &S = *(*I);
+    DEBUG(dbgs() << "SectionIdx: " << S.SectionIdx << ", Name: " << S.getName()
+                 << ", Size: " << S.Size << ", Offset: " << S.Offset
+                 << ", SectionData Size: " << S.size() << "\n");
+
+    // Align FileOff to whatever the alignment restrictions of the section are.
+    if (S.size()) {
+      if (S.Align)  {
+        for (size_t NewFileOff = (FileOff+S.Align-1) & ~(S.Align-1);
+             FileOff != NewFileOff; ++FileOff)
+          O << (char)0xAB;
+      }
+      O.write((char *)&S.getData()[0], S.Size);
+      FileOff += S.Size;
+    }
+
+    EmitSectionHeader(SHdrTable, S);
+  }
+
+  // Align output for the section table.
+  for (size_t NewFileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
+       FileOff != NewFileOff; ++FileOff)
+    O << (char)0xAB;
+
+  // Emit the section table itself.
+  O.write((char *)&SHdrTable.getData()[0], SHdrTable.size());
+}