[llvm-commits] LLD: patch WriterELF patch

Hemant Kulkarni khemant at codeaurora.org
Thu Sep 13 15:55:34 PDT 2012


I needed to modify two lines of code in it.

Since enum of ELDCLASS begins from 1 , 0 being no class:
+  e_ident(ELF::EI_CLASS, (options.is64Bit() ? ELF::ELFCLASS64
+                                            : ELF::ELFCLASS32));

Creating chunks of defined atoms that are right now unknown are noisy and will error out as unreachable in constructor od SectionChunk.
Hence
     if (type != DefinedAtom::typeUnknown){.. I create section chunk.

I think this patch is ready to commit. I am waiting a final good to go comment.

--
Hemant Kulkarni
khemant at codeaurora.org
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by the Linux Foundation


-----Original Message-----
From: Michael Spencer [mailto:bigcheesegs at gmail.com] 
Sent: Monday, September 10, 2012 6:47 PM
To: Hemant Kulkarni
Cc: llvm-commits at cs.uiuc.edu; kledzik at apple.com; Clow, Marshall
Subject: Re: LLD: patch WriterELF patch

On Mon, Sep 10, 2012 at 11:24 AM, Hemant Kulkarni
<khemant at codeaurora.org> wrote:
> I have changed the loops to range based loops, taken care of spaces and comma, removed #if 0 .. #endif, made sure to use BumpPtrAllocate for fixing leaks and removed the enums and directly use Support/ELF.h file enums.
>
> I have also removed Elf_Ehdr from ELFObjectFile class (Object/ELF.h) to make it consistent with other classes. I have changed the code that dependent on this change. Please take a look and comment on the changes.
>
> Thanks.
>
> --
> Hemant Kulkarni
> khemant at codeaurora.org
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by the Linux Foundation
>
>
> -----Original Message-----
> From: Michael Spencer [mailto:bigcheesegs at gmail.com]
> Sent: Wednesday, September 05, 2012 2:37 PM
> To: Hemant Kulkarni
> Cc: llvm-commits at cs.uiuc.edu; kledzik at apple.com; Clow, Marshall
> Subject: Re: LLD: patch WriterELF patch
>
> On Tue, Sep 4, 2012 at 12:30 PM, Hemant Kulkarni <khemant at codeaurora.org> wrote:
>> This patch adds ELF Writer basic infrastructure. It is based off of Mach-O
>> writer in lld tree. Some of the comments are a little verbose, they might
>> become irrelevant in future when they will be removed.
>>
>> ELFHeaderChunk is the class that sets the correct fields in Elf_Hdr
>> structure.
>> SectionChunk class is container for each section that will be in writer
>> output
>> ELFStringSectionChunk implements the string section as per SCO SYS V ABI
>> ELFSectionHeaderChunk is container to work with SectionChunk and other
>> custom sections made by linker to create a table of Elf_Shdr structures.
>>
>> Issues:
>> Symbol tables are not yet implemented; I will put in a new patch for symbol
>> table update. This might also involve modifying ReaderELF and deal with
>> TODO/FIXME in it.
>> Relocation fixups are not implemented yet.
>> The test infrastructure for LLD will need to be modified to read binary
>> files and test writer. I will add them so we can test Writer in make check
>> like test. For now, I run a modified lld-core utility that has options to
>> choose writer and I emit ELF binary. I then examine the file with readelf.
>>
>>
>>
>> --
>> Hemant Kulkarni
>> khemant at codeaurora.org
>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by
>> the Linux Foundation
>>
>>
>
>> Index: include/lld/ReaderWriter/WriterELF.h
>> ===================================================================
>> --- include/lld/ReaderWriter/WriterELF.h      (revision 163142)
>> +++ include/lld/ReaderWriter/WriterELF.h      (working copy)
>> @@ -13,13 +13,15 @@
>>  #include "lld/ReaderWriter/Writer.h"
>>  #include "lld/Core/LLVM.h"
>>  #include "llvm/ADT/StringRef.h"
>> +#include "llvm/Support/Endian.h"
>>
>> +#include <utility>
>>
>>  namespace lld {
>>
>>  ///
>>  /// The WriterOptionsELF class encapsulates options needed
>> -/// to process mach-o files.  You can create an WriterOptionsELF
>> +/// to process ELF files.  You can create an WriterOptionsELF
>>  /// instance from command line arguments or by subclassing and setting the
>>  /// instance variables in the subclass's constructor.
>>  ///
>> @@ -28,7 +30,7 @@
>>    virtual ~WriterOptionsELF();
>>
>>    ///
>> -  /// Creates a Options object from darwin linker command line arguments.
>> +  /// Creates a Options object from elf linker command line arguments.
>>    /// FIXME: to be replaced with new option processing mechanism.
>>    ///
>>    WriterOptionsELF(int argc, const char* argv[]);
>> @@ -39,7 +41,52 @@
>>    ///
>>    WriterOptionsELF();
>>
>> +  enum OutputKind {
>> +    outputDynamicExecutable,  // ET_EXEC
>> +    outputStaticExecutable,   // ET_EXEC
>> +    outputObjectFile,         // ET_REL
>> +    outputDylib,              // ET_DYN
>
> ELF has the following types:
>
> ET_REL 1 Relocatable object file
> ET_EXEC 2 Executable file
> ET_DYN 3 Shared object file
> ET_CORE 4 Core file
>
> Which should be in llvm/Support/ELF.h
>
>> +  };
>> +
>> +  enum Architecture {
>> +    arch_x86_64,
>> +    arch_x86,
>> +    arch_armv6,
>> +    arch_armv7,
>> +    arch_hexagon,
>> +  };
>
> Use values from llvm/Support/ELF.h
>
>> +  ///
>> +  /// Create a specific instance of an architecture
>> +  ///
>> +  WriterOptionsELF(const Architecture arch,
>> +                   const llvm::support::endianness endian,
>> +                   const bool is64Bit);
>> +  WriterOptionsELF(const OutputKind OK, const Architecture ARCH,
>> +                   const bool REL,
>> +                   const llvm::support::endianness endian,
>> +                   const bool is64Bit);
>
> These constructors should be in terms of e_ident (broken up), e_type, and
> e_machine.
>
>> +
>> +  OutputKind   outputKind() const       { return _outputkind; }
>> +  Architecture architecture() const     { return _architecture; }
>> +  bool         is64Bit() const          { return _is64Bit; }
>> +  llvm::support::endianness endianness() const { return _endian; }
>> +  StringRef    archName() const;
>> +  uint32_t     cpuType() const;
>> +  uint32_t     cpuSubtype() const;
>> +  bool         noTextRelocations() const { return _noTextRelocations; }
>> +  bool         addEntryPointLoadCommand() const;
>> +  bool         addUnixThreadLoadCommand() const;
>
> These two make no sense for ELF.
>
>> +  StringRef    entryPointName() const;
>> +  std::pair<llvm::support::endianness, bool>    getArchTypeClass() const;
>> +
>>  protected:
>> +  OutputKind                _outputkind;
>> +  Architecture              _architecture;
>> +  bool                      _noTextRelocations;
>> +  llvm::support::endianness _endian;
>> +  bool                      _is64Bit;
>> +  StringRef                 _customEntryPointName;
>> +
>>  };
>>
>>
>> Index: lib/ReaderWriter/ELF/WriterOptionsELF.cpp
>> ===================================================================
>> --- lib/ReaderWriter/ELF/WriterOptionsELF.cpp (revision 0)
>> +++ lib/ReaderWriter/ELF/WriterOptionsELF.cpp (revision 0)
>> @@ -0,0 +1,164 @@
>> +//===- lib/ReaderWriter/ELF/WriterOptionsELF.cpp ----------------------===//
>> +//
>> +//                             The LLVM Linker
>> +//
>> +// This file is distributed under the University of Illinois Open Source
>> +// License. See LICENSE.TXT for details.
>> +//
>> +//===----------------------------------------------------------------------===//
>> +
>> +#include "lld/ReaderWriter/WriterELF.h"
>> +
>> +#include "llvm/Support/Debug.h"
>> +#include "llvm/Support/ELF.h"
>> +#include "llvm/Support/ErrorHandling.h"
>> +#include "llvm/Support/system_error.h"
>> +
>> +#include "llvm/ADT/SmallVector.h"
>> +#include "llvm/ADT/StringRef.h"
>> +
>> +// TODO: MachOFormat.hpp is a MachO variant of what is include/Support/ELF.h
>> +//       Will try for the time being to use ELF.h
>> +// #include "MachOFormat.hpp"
>
> Remove.
>
>> +
>> +namespace lld {
>> +
>> +WriterOptionsELF::WriterOptionsELF()
>> +  : _outputkind(outputDynamicExecutable)
>> +  , _architecture(arch_x86)
>> +  , _noTextRelocations(true)
>> +  , _endian (llvm::support::little)
>> +  , _is64Bit(false){
>> +}
>> +
>> +// This interface was added to allow a user to select a particular
>> +// output architecture.
>> +// FIXME: We need to add probably more parameters such as PageZero address/size?
>> +WriterOptionsELF::WriterOptionsELF(const WriterOptionsELF::Architecture ARCH,
>> +                                   const llvm::support::endianness endian,
>> +                                   const bool is64Bit)
>> +  : _outputkind(outputStaticExecutable)
>> +  , _architecture(ARCH)
>> +  , _noTextRelocations(true)
>> +  , _endian (endian)
>> +  , _is64Bit(is64Bit){
>> +}
>> +
>> +WriterOptionsELF::WriterOptionsELF(const WriterOptionsELF::OutputKind OK,
>> +                                   const WriterOptionsELF::Architecture ARCH,
>> +                                   const bool REL,
>> +                                   const llvm::support::endianness endian,
>> +                                   const bool is64Bit)
>> +  : _outputkind(OK)
>> +  , _architecture(ARCH)
>> +  , _noTextRelocations(REL)
>> +  , _endian (endian)
>> +  , _is64Bit(is64Bit){
>> +}
>> +
>> +WriterOptionsELF::~WriterOptionsELF() {
>> +}
>> +
>> +StringRef WriterOptionsELF::archName() const {
>> +  switch ( _architecture ) {
>> +    case arch_x86_64:
>> +      return StringRef("x86_64");
>> +    case arch_x86:
>> +       return StringRef("i386");
>> +    case arch_armv6:
>> +       return StringRef("armv6");
>> +    case arch_armv7:
>> +       return StringRef("armv7");
>> +    case arch_hexagon:
>> +       return StringRef("hexagon");
>> +  }
>> +  llvm_unreachable("unknown arch");
>> +}
>> +
>> +uint32_t WriterOptionsELF::cpuType() const {
>> +  switch ( _architecture ) {
>> +    case arch_x86_64:
>> +      return llvm::ELF::EM_X86_64;
>> +    case arch_x86:
>> +      return llvm::ELF::EM_386;
>> +    case arch_armv6:
>> +    case arch_armv7:
>> +      return llvm::ELF::EM_ARM;
>> +    case arch_hexagon:
>> +      return llvm::ELF::EM_HEXAGON;
>> +  }
>> +  llvm_unreachable("unknown arch");
>> +}
>> +
>> +uint32_t WriterOptionsELF::cpuSubtype() const {
>> +  switch ( _architecture ) {
>> +    case arch_x86_64:
>> +      return llvm::ELF::EM_X86_64;
>> +    case arch_x86:
>> +      return llvm::ELF::EM_386;
>> +    case arch_armv6:
>> +    case arch_armv7:
>> +      return llvm::ELF::EM_ARM;
>> +//TODO sub-type will probably mean hexagon arch version/v[26], this
>> +// will have to be locally enumerated.
>
> What do you mean by enumerated?
>
>> +    case arch_hexagon:
>> +       return llvm::ELF::EM_HEXAGON;
>> +  }
>> +  llvm_unreachable("unknown arch");
>> +}
>> +
>> +bool WriterOptionsELF::addEntryPointLoadCommand() const {
>> +  switch ( _outputkind ) {
>> +    case outputDynamicExecutable:
>> +    case outputStaticExecutable:
>> +      // Only main executables have an entry point
>> +      return true;
>> +    case outputDylib:
>> +    case outputObjectFile:
>> +      return false;
>> +  }
>> +  llvm_unreachable("unknown outputkind");
>> +}
>> +
>> +bool WriterOptionsELF::addUnixThreadLoadCommand() const {
>> +  switch ( _outputkind ) {
>> +    case outputDynamicExecutable:
>> +    case outputStaticExecutable:
>> +      // Only main executables have an entry point
>> +      return true;
>> +    case outputDylib:
>> +    case outputObjectFile:
>> +      return false;
>> +  }
>> +  llvm_unreachable("unknown outputkind");
>> +}
>> +
>> +StringRef WriterOptionsELF::entryPointName() const {
>> +  switch ( _outputkind ) {
>> +    case outputDynamicExecutable:
>> +    case outputStaticExecutable:
>> +      // Only main executables have an entry point
>> +      if ( ! _customEntryPointName.empty() ) {
>> +        return _customEntryPointName;
>> +      }
>> +      else {
>> +          return StringRef("start");
>> +      }
>> +      break;
>> +    case outputDylib:
>> +    case outputObjectFile:
>> +      return StringRef();
>> +  }
>> +  llvm_unreachable("unknown outputkind");
>> +}
>> +
>> +std::pair<llvm::support::endianness, bool>
>> +    WriterOptionsELF::getArchTypeClass() const {
>> +  return (std::pair<llvm::support::endianness, bool>)
>> +               std::make_pair(_endian,_is64Bit);
>> +}
>> +
>> +
>> +
>> +} // namespace lld
>> +
>> Index: lib/ReaderWriter/ELF/WriterELF.cpp
>> ===================================================================
>> --- lib/ReaderWriter/ELF/WriterELF.cpp        (revision 163142)
>> +++ lib/ReaderWriter/ELF/WriterELF.cpp        (working copy)
>> @@ -9,27 +9,1143 @@
>>
>>  #include "lld/ReaderWriter/WriterELF.h"
>>
>> +#include "llvm/Object/ELF.h"
>> +
>>  #include "llvm/Support/Debug.h"
>> +#include "llvm/Support/ELF.h"
>> +#include "llvm/Support/ErrorHandling.h"
>> +#include "llvm/Support/FileOutputBuffer.h"
>> +#include "llvm/Support/Format.h"
>> +#include "llvm/Support/raw_ostream.h"
>> +#include "llvm/Support/system_error.h"
>> +#include "llvm/Support/MathExtras.h"
>>
>> +#include "llvm/ADT/ArrayRef.h"
>> +#include "llvm/ADT/DenseMap.h"
>> +#include "llvm/ADT/OwningPtr.h"
>> +#include "llvm/ADT/SmallVector.h"
>> +#include "llvm/ADT/StringMap.h"
>> +#include "llvm/ADT/StringRef.h"
>>
>> +#include "lld/Core/DefinedAtom.h"
>> +#include "lld/Core/File.h"
>> +#include "lld/Core/InputFiles.h"
>> +#include "lld/Core/Reference.h"
>> +#include "lld/Core/SharedLibraryAtom.h"
>> +
>> +#include <vector>
>> +#include <map>
>> +#include <string.h>
>> +
>> +#include "ReferenceKinds.h"
>> +
>> +using namespace llvm;
>> +using namespace llvm::object;
>>  namespace lld {
>>  namespace elf {
>>
>> -// define ELF writer class here
>>
>> +template <support::endianness target_endianness, bool is64Bits>
>> +class ELFWriter;
>>
>> -} // namespace elf
>> +template  <support::endianness target_endianness, bool is64Bits>
>> +struct Elf_Ehdr {
>> +    LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
>> +    unsigned char e_ident[ELF::EI_NIDENT]; // ELF Identification bytes
>> +    Elf_Half e_type;     // Type of file (see ET_*)
>> +    Elf_Half e_machine;  // Required architecture for this file (see EM_*)
>> +    Elf_Word e_version;  // Must be equal to 1
>> +    Elf_Addr e_entry;    // Address to jump to in order to start program
>> +    Elf_Off  e_phoff;    // Program header table's file offset, in bytes
>> +    Elf_Off  e_shoff;    // Section header table's file offset, in bytes
>> +    Elf_Word e_flags;    // Processor-specific flags
>> +    Elf_Half e_ehsize;   // Size of ELF header, in bytes
>> +    Elf_Half e_phentsize;// Size of an entry in the program header table
>> +    Elf_Half e_phnum;    // Number of entries in the program header table
>> +    Elf_Half e_shentsize;// Size of an entry in the section header table
>> +    Elf_Half e_shnum;    // Number of entries in the section header table
>> +    Elf_Half e_shstrndx; // Section header table index of section name
>> +                                  // string table
>> +    bool checkMagic() const {
>> +      return (memcmp(e_ident, ELF::ElfMagic, strlen(ELF::ElfMagic))) == 0;
>> +    }
>> +    unsigned char getFileClass() const { return e_ident[ELF::EI_CLASS]; }
>> +    unsigned char getDataEncoding() const { return e_ident[ELF::EI_DATA]; }
>> +  };
>
> Why is this being coppied from llvm/Object/ELF.h?
>
>>
>> -Writer* createWriterELF(const WriterOptionsELF &options) {
>> -  assert(0 && "ELF support not implemented yet");
>> -  return nullptr;
>> +//
>> +// A Chunk is a contiguous range of space.  This idea is copied from the,
>> +// "Chunk" used by Mach-O
>> +//
>> +template <support::endianness target_endianness, bool is64Bits>
>> +class Chunk {
>> +public:
>> +  LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
>> +  virtual             ~Chunk() { }
>> +  virtual StringRef   segmentName() const = 0;
>> +  virtual bool        occupiesNoDiskSpace();
>> +  virtual void        write(uint8_t *fileBuffer) = 0;
>> +  void                assignFileOffset(uint64_t &curOff, uint64_t &curAddr);
>> +  virtual const char* info() = 0;
>> +  uint64_t             size() const;
>> +  uint64_t            address() const;
>> +  uint64_t             fileOffset() const;
>> +  uint64_t            align2() const;
>> +  static uint64_t     alignTo(uint64_t value, uint8_t align2);
>> +
>> +protected:
>> +                      Chunk();
>> +
>> +  uint64_t             _size;
>> +  uint64_t            _address;
>> +  uint64_t             _fileOffset;
>> +  uint64_t            _align2;
>> +};
>> +
>> +
>> +
>> +// This could functionally be inside the SectionChunk, but c++ standard does not
>> +// allow the vector of local types.
>
> C++11 does.
>
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +  struct AtomInfo {
>> +    LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
>> +    const DefinedAtom  *atom;
>> +    uint64_t            offsetInSection;
>> +  };
>> +//
>> +// A Section represents a set of Atoms assigned to a specific
>> +// ELF Section
>> +//
>> +template <support::endianness target_endianness, bool is64Bits>
>> +class SectionChunk : public Chunk <target_endianness, is64Bits> {
>> +public:
>> +  LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
>
> LLVM_ELF_IMPORT_TYPES isn't needed here.
>
>> +  SectionChunk  (DefinedAtom::ContentType,
>> +                StringRef sectionName,
>> +                const WriterOptionsELF &options,
>> +                class ELFWriter<target_endianness, is64Bits> &writer);
>> +
>> +  virtual StringRef          segmentName() const;
>> +  virtual bool               occupiesNoDiskSpace();
>> +  virtual void               write(uint8_t *fileBuffer);
>> +  virtual const char*        info();
>> +  StringRef                  sectionName();
>> +  uint32_t                   flags() const;
>> +  uint32_t                   type() const;
>> +  uint32_t                   permissions();
>> +  void                       appendAtom(const DefinedAtom*);
>> +
>> +
>> +
>> +  const std::vector<AtomInfo<target_endianness,is64Bits> >& atoms() const;
>> +
>> +private:
>> +  StringRef                 _segmentName;
>> +  StringRef                 _sectionName;
>> +  const WriterOptionsELF    &_options;
>> +  class ELFWriter<target_endianness, is64Bits>           &_writer;
>> +  uint32_t                  _flags;
>> +  uint32_t                  _type;
>> +  uint32_t                  _permissions;
>> +
>> +  std::vector<AtomInfo<target_endianness,is64Bits> >
>> +                            _atoms;
>> +};
>> +
>> +//
>> +// An ELFHeaderChunk represents the Elf[32/64]_Ehdr structure at the start
>> +// of an ELF executable file.
>> +//
>> +template<support::endianness target_endianness, bool is64Bits>
>> +class ELFHeaderChunk : public Chunk <target_endianness, is64Bits> {
>> +public:
>> +  LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
>
> LLVM_ELF_IMPORT_TYPES isn't needed here.
>
>> +
>> +  ELFHeaderChunk(const WriterOptionsELF &options,
>> +                 const File &file);
>> +
>> +  void e_ident(int i, unsigned char c)      { _eh.e_ident[i] = c; }
>> +  void e_type(uint16_t type)                { _eh.e_type = type; }
>> +  void e_machine(uint16_t machine)          { _eh.e_machine = machine; }
>> +  void e_version(uint32_t version)          { _eh.e_version = version; }
>> +  void e_entry(uint64_t entry)              { _eh.e_entry = entry; }
>> +  void e_phoff(uint64_t phoff)               { _eh.e_phoff = phoff; }
>> +  void e_shoff(uint64_t shoff)               { _eh.e_shoff = shoff; }
>> +  void e_flags(uint32_t flags)              { _eh.e_flags = flags; }
>> +  void e_ehsize(uint16_t ehsize)            { _eh.e_ehsize = ehsize; }
>> +  void e_phentsize(uint16_t phentsize)      { _eh.e_phentsize = phentsize; }
>> +  void e_phnum(uint16_t phnum)              { _eh.e_phnum = phnum; }
>> +  void e_shentsize(uint16_t shentsize)      { _eh.e_shentsize = shentsize; }
>> +  void e_shnum(uint16_t shnum)              { _eh.e_shnum = shnum; }
>> +  void e_shstrndx(uint16_t shstrndx)        { _eh.e_shstrndx = shstrndx; }
>> +
>> +  uint64_t  size() { return sizeof (Elf_Ehdr<target_endianness, is64Bits>); }
>> +
>> +  virtual StringRef     segmentName() const;
>> +  virtual void          write(uint8_t *fileBuffer);
>> +  virtual const char*   info();
>> +
>> +private:
>> +  uint32_t              filetype(WriterOptionsELF::OutputKind kind);
>> +  Elf_Ehdr<target_endianness, is64Bits>             _eh;
>> +};
>> +
>> +//
>> +// An ELFSectionHeaderChunk represents the Elf[32/64]_Shdr structure that
>> +// is placed right after the ELFHeader.
>> +// When this is finished it will need to update the header with the size
>> +// and number of section headers, e_shentsize, e_shnum
>> +//
>> +template <support::endianness target_endianness, bool is64Bits>
>> +class ELFSectionHeaderChunk : public Chunk <target_endianness, is64Bits> {
>> +public:
>> +  LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
>> +  typedef object::Elf_Shdr_Impl<target_endianness, is64Bits> Elf_Shdr;
>> +  ELFSectionHeaderChunk(const WriterOptionsELF &options,
>> +                        class ELFWriter<target_endianness, is64Bits>&);
>> +
>> +  virtual StringRef     segmentName() const;
>> +  virtual void          write(uint8_t *fileBuffer);
>> +  virtual const char*   info();
>> +  void                  computeSize(const lld::File &file);
>> +  uint16_t              count();
>> +  uint16_t              size();
>> +
>> +  const std::vector<Elf_Shdr*> sectionInfo(){
>> +    return _sectionInfo;
>> +  }
>> +
>> +//  void                  append(Elf_Shdr *shdr);
>> +  bool                  is64Bit() { return _options.is64Bit(); }
>> +
>> +private:
>> +  const WriterOptionsELF   &_options;
>> +  class ELFWriter<target_endianness, is64Bits>          &_writer;
>> +
>> +  std::vector<Elf_Shdr*> _sectionInfo;
>
> Who owns the memory pointed to?
>
>> +};
>> +
>> +
>> +// ELFStringSectionChunk represents the shstr section
>> +// This is a contiguous memory that has all the symbol strings
>> +// each ending with null character. We might need more than one such chunks
>> +// shstrtab for setting e_shstrndx in ELHHeaderChunk and strtab for use with
>> +// symtab
>> +//
>> +template <support::endianness target_endianness, bool is64Bits>
>> +class ELFStringSectionChunk : public Chunk <target_endianness, is64Bits> {
>> +public:
>> +  LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
>> +  ELFStringSectionChunk(const WriterOptionsELF &options,
>> +                        class ELFWriter<target_endianness, is64Bits> &writer,
>> +                        StringRef SecName);
>> +  uint64_t addString(StringRef SymName);
>> +
>> +
>> +  virtual StringRef          segmentName() const;
>> +  virtual void               write(uint8_t *fileBuffer);
>> +  virtual const char*        info();
>> +  StringRef                  sectionName();
>> +
>> +
>> +
>> +private:
>> +  StringRef _segName;
>> +  std::vector<StringRef> _StringSection;
>> +  StringRef _sectionName;
>> +  class ELFWriter<target_endianness, is64Bits> &_writer;
>> +  const WriterOptionsELF &_options;
>> +
>> +};
>> +
>> +#if 0
>> +//
>> +// ELFSymbolTableChunk represents the Symbol table as per ELF ABI
>> +// This is a table with Elf[32/64]_Sym entries in it.
>> +//
>> +template <support::endianness target_endianness, bool is64Bits>
>> +class ELFSymbolTableChunk : public Chunk<target_endianness, i64Bits> {
>> +public:
>> +  LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
>> +  ELFSymbolTableChunk(class WriterOptionsELF &options,
>> +                      class ELFWriter<target_endianness, is64Bits> &writer,
>> +                      StringRef SecName,
>> +                      class ELFStringSectionChunk<target_endianness, is64Bits>
>> +                      &ShStr);
>> +  void addSymbol(const Atom *a);
>> +
>> +
>> +  virtual StringRef          segmentName() const;
>> +  virtual void               write(uint8_t *fileBuffer);
>> +  virtual const char*        info();
>> +  StringRef                  sectionName();
>> +
>> +
>> +
>> +private:
>> +  StringRef _segName;
>> +  std::vector<Elf_Sym*> _SymbolTable;
>> +  StringRef _sectionName;
>> +  class ELFWriter<target_endianness, is64Bits> &_writer;
>> +  class WriterOptionsELF &_options;
>> +  class ELFStringSectionChunk<target_endianness, is64Bits> &_stringSection;
>> +  uint64_t _offsetInStringTable;
>> +};
>> +
>> +#endif
>> +//
>> +// An ELFProgramHeaderChunk represents the Elf[32/64]_Phdr structure near
>> +// the start of an ELF executable file. Will need to update ELFHeader's
>> +// e_phentsize/e_phnum when done.
>> +//
>> +template <support::endianness target_endianness, bool is64Bits>
>> +class ELFProgramHeaderChunk : public Chunk <target_endianness, is64Bits> {
>> +public:
>> +  LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
>> +  ELFProgramHeaderChunk(ELFHeaderChunk<target_endianness, is64Bits>&,
>> +                        const WriterOptionsELF &options,
>> +                        const File &file);
>> +
>> +
>> +  virtual StringRef     segmentName() const;
>> +  virtual void          write(uint8_t *fileBuffer);
>> +  virtual const char*   info();
>> +
>> +private:
>> +  uint32_t              filetype(WriterOptionsELF::OutputKind kind);
>> +  Elf_Ehdr<target_endianness, is64Bits>             _ph;
>> +};
>> +
>> +
>> +//===----------------------------------------------------------------------===//
>> +//  Chunk
>> +//===----------------------------------------------------------------------===//
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +Chunk<target_endianness, is64Bits>::Chunk()
>> + : _size(0), _address(0), _fileOffset(0), _align2(0) {
>>  }
>>
>> -WriterOptionsELF::WriterOptionsELF() {
>> +template <support::endianness target_endianness, bool is64Bits>
>> +bool Chunk<target_endianness, is64Bits>::occupiesNoDiskSpace() {
>> +  return false;
>>  }
>>
>> -WriterOptionsELF::~WriterOptionsELF() {
>> +template <support::endianness target_endianness, bool is64Bits>
>> +uint64_t Chunk<target_endianness, is64Bits>::size() const {
>> +  return _size;
>>  }
>>
>> +template <support::endianness target_endianness, bool is64Bits>
>> +uint64_t Chunk<target_endianness, is64Bits>::align2() const {
>> +  return _align2;
>> +}
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +uint64_t Chunk<target_endianness, is64Bits>::address() const {
>> +  return _address;
>> +}
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +uint64_t Chunk<target_endianness, is64Bits>::fileOffset() const {
>> +  return _fileOffset;
>> +}
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +uint64_t Chunk<target_endianness, is64Bits>::
>> +         alignTo(uint64_t value, uint8_t align2) {
>> +
>> +  uint64_t align = 1 << align2;
>> +  return ( (value + (align-1)) & (-align) );
>> +}
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +void Chunk<target_endianness, is64Bits>::
>> +     assignFileOffset(uint64_t &curOffset, uint64_t &curAddress) {
>> +  if ( this->occupiesNoDiskSpace() ) {
>> +    // FileOffset does not change, but address space does change.
>
> s/address space/virtual address/
>
>> +    uint64_t alignedAddress = alignTo(curAddress,
>> +                            _align2?(uint8_t) llvm::Log2_64(_align2):0);
>> +   _address = alignedAddress;
>> +   curAddress = alignedAddress + _size;
>> +  }
>> +  else {
>> +    // FileOffset and address both move by _size amount after alignment.
>> +    uint64_t alignPadding = alignTo(curAddress, _align2?
>> +                            (uint8_t) llvm::Log2_64(_align2):0) - curAddress;
>> +    _fileOffset = curOffset + alignPadding;
>> +    _address = curAddress + alignPadding;
>> +    curOffset = _fileOffset + _size;
>> +    curAddress = _address + _size;
>> +  }
>> +
>> +  DEBUG_WITH_TYPE("WriterELF-layout", dbgs()
>> +                      << "   fileOffset="
>> +                      << format("0x%08X", _fileOffset)
>> +                      << " address="
>> +                      << format("0x%016X", _address)
>> +                      << " info=" << this->info() << "\n");
>> +}
>> +
>> +//===----------------------------------------------------------------------===//
>> +//  SectionChunk
>> +//===----------------------------------------------------------------------===//
>> +
>> +template< support::endianness target_endianness, bool is64Bits>
>> +SectionChunk<target_endianness,is64Bits>::SectionChunk
>> +                                        (DefinedAtom::ContentType type,
>> +                                        StringRef sectionName,
>> +                                        const WriterOptionsELF &options,
>> +                                        ELFWriter<target_endianness, is64Bits>
>> +                                        &writer)
>> + :  _options(options)
>> + , _writer(writer) {
>> +  switch ( type ) {
>> +
>> +    case DefinedAtom::typeCode:
>> +                              _segmentName = StringRef("PT_LOAD");
>> +                              _sectionName = sectionName;
>> +                              _flags       = ELF::SHF_ALLOC|ELF::SHF_EXECINSTR;
>> +                              _type        = ELF::SHT_PROGBITS;
>> +                              break;
>> +
>> +    case DefinedAtom::typeData:
>> +                              _segmentName = StringRef("PT_LOAD");
>> +                              _sectionName = sectionName;
>> +                              _flags       = ELF::SHF_ALLOC|ELF::SHF_WRITE;
>> +                              _type        = ELF::SHT_PROGBITS;
>> +                              break;
>> +
>> +    case DefinedAtom::typeZeroFill:
>> +                              _segmentName = StringRef("PT_LOAD");
>> +                              _sectionName = StringRef(".bss");
>> +                              _flags       = ELF::SHF_ALLOC|ELF::SHF_WRITE;
>> +                              _type        = ELF::SHT_NOBITS;
>> +                              break;
>> +
>> +    default:
>> +                              _segmentName = StringRef("PT_NULL");
>> +                              _sectionName = StringRef("");
>> +                              _flags       = 0;
>> +                              _type        = ELF::SHT_NULL;
>> +      //assert(0 && "TO DO: add support for more sections");
>> +     }
>> + }
>
> The whitespace here seems rather messed up.
>
>> +
>> +
>> +template< support::endianness target_endianness, bool is64Bits>
>> +bool SectionChunk<target_endianness,is64Bits>::occupiesNoDiskSpace() {
>> +  //return ( (_flags & SECTION_TYPE) == S_ZEROFILL );
>> +  return false;
>> +}
>> +
>> +template< support::endianness target_endianness, bool is64Bits>
>> +StringRef SectionChunk<target_endianness,is64Bits>::segmentName() const {
>> +  return _segmentName;
>> +}
>> +
>> +template< support::endianness target_endianness, bool is64Bits>
>> +StringRef SectionChunk<target_endianness,is64Bits>::sectionName() {
>> +  return _sectionName;
>> +}
>> +
>> +template< support::endianness target_endianness, bool is64Bits>
>> +uint32_t SectionChunk<target_endianness,is64Bits>::flags() const {
>> +  return _flags;
>> +}
>> +
>> +template< support::endianness target_endianness, bool is64Bits>
>> +uint32_t SectionChunk<target_endianness,is64Bits>::type()
>> +      const {
>> +  return _type;
>> +}
>> +template< support::endianness target_endianness, bool is64Bits>
>> +uint32_t SectionChunk<target_endianness,is64Bits>::permissions() {
>> +  return _permissions;
>> +}
>> +
>> +template< support::endianness target_endianness, bool is64Bits>
>> +const char* SectionChunk<target_endianness,is64Bits>::info() {
>> +  return _sectionName.data();
>> +}
>> +
>> +template< support::endianness target_endianness, bool is64Bits>
>> +const std::vector<AtomInfo<target_endianness,is64Bits> >&
>> +//const std::vector<SectionChunk<target_endianness,is64Bits>::AtomInfo>&
>> +      SectionChunk<target_endianness,is64Bits>::atoms() const {
>> +  return _atoms;
>> +}
>> +
>> +
>> +template< support::endianness target_endianness, bool is64Bits>
>> +void SectionChunk<target_endianness,is64Bits>::appendAtom(const DefinedAtom
>> +                                                          *atom) {
>> +  // Figure out offset for atom in this section given alignment constraints.
>> +  uint64_t offset = this->_size;
>> +  DefinedAtom::Alignment atomAlign = atom->alignment();
>> +  uint64_t align2 = 1 << atomAlign.powerOf2;
>> +  uint64_t requiredModulus = atomAlign.modulus;
>> +  uint64_t currentModulus = (offset % align2);
>> +  if ( currentModulus != requiredModulus ) {
>
> no space after or before ().
>
>> +    if ( requiredModulus > currentModulus )
>> +      offset += requiredModulus-currentModulus;
>> +    else
>> +      offset += align2+requiredModulus-currentModulus;
>
> Spaces around -.
>
>> +  }
>> +  // Record max alignment of any atom in this section.
>> +  if ( align2 > this->_align2 )
>> +    this->_align2 = align2;
>> +  // Assign atom to this section with this offset.
>> +  AtomInfo<target_endianness,is64Bits> ai = {atom, offset};
>
> Space after ,
>
>> +  _atoms.push_back(ai);
>> +  // Update section size to include this atom.
>> +  this->_size = offset + atom->size();
>> +  // Update permissions
>> +  DefinedAtom::ContentPermissions perms = atom->permissions();
>> +
>> +  // TODO: Check content permissions and figure out what to do with .bss
>> +  if ( (perms & DefinedAtom::permR__) == DefinedAtom::permR__ )
>> +    _permissions |= ELF::SHF_ALLOC;
>> +  if ( (perms & DefinedAtom::permRW_) == DefinedAtom::permRW_ )
>> +    _permissions |= (ELF::SHF_ALLOC | ELF::SHF_WRITE);
>> +  if ( (perms & DefinedAtom::permR_X) == DefinedAtom::permR_X )
>> +    _permissions |= (ELF::SHF_ALLOC | ELF::SHF_EXECINSTR);
>> +}
>> +
>> +
>> +template< support::endianness target_endianness, bool is64Bits>
>> +void SectionChunk<target_endianness,is64Bits>::write(uint8_t *chunkBuffer) {
>> +  // Each section's content is just its atoms' content.
>> +  for (const AtomInfo<target_endianness,is64Bits> &atomInfo : _atoms ) {
>
> const auto &atomInfo
>
>> +    // Copy raw content of atom to file buffer.
>> +    ArrayRef<uint8_t> content = atomInfo.atom->rawContent();
>> +    uint64_t contentSize = content.size();
>> +    if ( contentSize == 0 )
>> +      continue;
>> +    uint8_t* atomContent = chunkBuffer + atomInfo.offsetInSection;
>> +    ::memcpy(atomContent, content.data(), contentSize);
>> +    // Apply fixups to file buffer
>> +// XXX_SM : TODO key element here
>> +#if 0
>> +    for (const Reference *ref : *atomInfo.atom) {
>> +      uint32_t offset = ref->offsetInAtom();
>> +      uint64_t targetAddress = 0;
>> +
>> +      if ( ref->target() != nullptr )
>> +
>> +        targetAddress = _writer.addressOfAtom(ref->target());
>> +      uint64_t fixupAddress = _writer.addressOfAtom(atomInfo.atom) + offset;
>> +      _writer.kindHandler()->applyFixup(ref->kind(), ref->addend(),
>> +                            &atomContent[offset], fixupAddress, targetAddress);
>> +    }
>> +#endif
>> +  }
>> +}
>> +
>> +//===----------------------------------------------------------------------===//
>> +//  ELFStringSectionChunk
>> +//===----------------------------------------------------------------------===//
>> +template <support::endianness target_endianness, bool is64Bits>
>> +ELFStringSectionChunk<target_endianness,is64Bits>::ELFStringSectionChunk
>> +                      (const WriterOptionsELF &options,
>> +                       class ELFWriter<target_endianness, is64Bits> &writer,
>> +                       StringRef SecName)
>> +  : _segName("PT_NULL")
>> +  , _sectionName(SecName)
>> +  , _writer(writer)
>> +  , _options(options){
>> +
>> +// First Add a null character. It also occupies 1 byte
>> +  StringRef empty("");
>> +  _StringSection.push_back(empty);
>> +  this->_size = 1;
>> +// Assuming we need two string sections: one for sections one for symbols
>> +// following code is useless
>> +#if 0
>> +// Name of the string section is also stored inside the section
>> +  _StringSection.push_back(SecName);
>> +//take into account the size of this string + null character that succeeds
>> +  _size += SecName.size() + 1;
>> +#endif
>> +
>> +  }
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +uint64_t  ELFStringSectionChunk<target_endianness,is64Bits>::addString
>> +                                (StringRef SymName) {
>> +  uint64_t  offset;
>> +  offset = this->_size;
>> +  _StringSection.push_back(SymName);
>> +  this->_size += SymName.size() + 1;
>> +
>> +  return offset;
>> +}
>> +
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +const char* ELFStringSectionChunk<target_endianness,is64Bits>::info () {
>> +  return _sectionName.data();
>> +}
>
> What does info actually mean?
>
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +StringRef ELFStringSectionChunk<target_endianness,is64Bits>::sectionName() {
>> +  return _sectionName ;
>> +}
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +StringRef ELFStringSectionChunk<target_endianness,is64Bits>::segmentName()
>> +                                                             const {
>> +  return _segName;
>> +}
>> +
>> +// We need to unwrap the _StringSection and then make one large memory
>> +// chunk of null terminated strings
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +void ELFStringSectionChunk<target_endianness,is64Bits>::write
>> +                          (uint8_t *chunkbuffer) {
>> +  uint64_t chunkoffset = 0;
>> +  std::vector<StringRef>::iterator it,ie;
>> +
>> +
>> +  for (it=_StringSection.begin(),ie=_StringSection.end(); it!=ie;++it) {
>> +    ::memcpy(chunkbuffer+chunkoffset,it->data(),it->size());
>> +    chunkoffset += it->size();
>> +    ::memcpy(chunkbuffer+chunkoffset,"",1);
>> +    chunkoffset += 1;
>> +  }
>> +}
>> +
>> +
>> +#if 0
>> +//===----------------------------------------------------------------------===//
>> +//  ELFSymbolTableChunk
>> +//===----------------------------------------------------------------------===//
>> +template< support::endianness target_endianness, bool is64Bits>
>> +ELFSymbolTableChunk::ELFSymbolTableChunk
>> +                    (class WriterOptionsELF &options,
>> +                     class ELFWriter<target_endianess, is64bits> &writer,
>> +                     StringRef SecName,
>> +                     class ELFStringSectionChunk<target_endianess, is64bits>
>> +                     &Shstr)
>> +  : _segName("PT_NULL")
>> +  , _sectionName(SecName)
>> +  , _writer(writer)
>> +  , _options(options)
>> +  , _stringSection(Shstr) {
>> +  Elf_Sym *symbol = new Elf_Sym;
>> +  memset ((void *)symbol,0,sizeof(elf_sym));
>> +  _SymbolTable.push_back(symbol);
>> +  _offsetInStringTable = _stringSection.addString(SecName)
>> +}
>> +
>> +
>> +//We examine each property of atom to infer the various st_* fields in Elf*_Sym
>> +
>> +template< support::endianness target_endianness, bool is64Bits>
>> +ELFSymbolTableChunk<target_endianness,is64Bits>::addSymbol(const Atom *a) {
>> + Elf_Sym *symbol = new Elf_Sym;
>> + unsigned char b,t;
>> + symbol->st_name = _stringSection.addString(a->name());
>> +// TODO: Account for common symbols
>> + if (a->definition == lld::Atom::definitionRegular) {
>> +     symbol->st_value = a->rawContent();
>> +     symbol->st_size = a->size();
>> +     lld::DefinedAtom::ContentType ct;
>> +     switch (ct = a->getType()){
>> +        case  DefinedAtom::typeCode:
>> +                                         t = ELF::STT_FUNC;
>> +                                         break;
>> +        case  DefinedAtom::typeData:
>> +                                         t = ELF::STT_OBJECT;
>> +                                         break;
>> +        case  DefinedAtom::typeZeroFill:
>> +                                         t = ELF::STT_COMMON;
>> +                                         break;
>> +        case default:
>> +                                         t = ELF::STT_NOTYPE;
>> +     }
>> +
>> +// TODO: Find out how to incorporate STB_HIOS STB_LOOS
>> +// STB_HIPROC and STB_LOPROC
>> +
>> +     if (a->scope() != DefinedAtom::scopeGlobal &&
>> +         a->merge() != DefinedAtom::mergeAsWeak)
>> +             b = ELF::STB_LOCAL;
>> +     else if (a->merge == DefinedAtom::mergeAsWeak)
>> +             b= ELF::STB_WEAK;
>> +     else
>> +             b = ELF::STB_GLOBAL;
>> + }
>> + else if (a->definition == lld::Atom::definitionAbsolute) {
>> +     symbol->st_value = a->value();
>> +     symbol->st_size = 0;
>> + }
>> + else {
>> +     symbol->st_value = 0;
>> +     symbol->st_size=0;
>> +     t = ELF::STT_NOTYPE;
>> +     b = ELF::STB_LOCAL;
>> + }
>> +
>> +// This will set the st_info field in Elf_Sym
>> +     symbol->setBindingAndType(b,t);
>> +}
>> +
>> +#endif
>
> Can you just remove all the #if 0 stuff for now?
>
>> +
>> +
>> +
>> +//===----------------------------------------------------------------------===//
>> +//  ELFHeaderChunk
>> +//===----------------------------------------------------------------------===//
>> +template<support::endianness target_endianness, bool is64Bits>
>> +ELFHeaderChunk <target_endianness,is64Bits>
>> +              ::ELFHeaderChunk(const WriterOptionsELF &options,
>> +                               const File &file) {
>
> Why is File used sometimes and ELFFile used others?
>
>> +  this->_size = this->size();
>
> Don't use this-> unless it's required.
>
>> +
>> +  this->e_ident(ELF::EI_MAG0, 0x7f);
>> +  this->e_ident(ELF::EI_MAG1, 'E');
>> +  this->e_ident(ELF::EI_MAG2, 'L');
>> +  this->e_ident(ELF::EI_MAG3, 'F');
>> +  if (options.is64Bit())
>> +    this->e_ident(ELF::EI_CLASS, 2);
>> +  else
>> +    this->e_ident(ELF::EI_CLASS, 1);
>> +
>> +  if (options.endianness() == support::little)
>> +    this->e_ident(ELF::EI_DATA, ELF::ELFDATA2LSB);
>> +  else
>> +    this->e_ident(ELF::EI_DATA, ELF::ELFDATA2MSB);
>> +
>> +  this->e_ident(ELF::EI_VERSION, 1);
>> +  this->e_ident(ELF::EI_OSABI, ELF::ELFOSABI_NONE);
>> +
>> +  this->e_type(this->filetype(options.outputKind()));
>> +  this->e_machine(options.cpuType());
>> +  this->e_version(1);
>> +
>> +  this->e_entry((uint64_t)0x0);
>> +  this->e_phoff((uint64_t)this->_size);
>> +  this->e_shoff((uint64_t)0x0);
>> +
>> +
>> +  this->e_flags(0);
>> +  this->e_ehsize(this->_size);
>> +  this->e_phentsize(0);
>> +  this->e_phnum(0);
>> +  this->e_shentsize(0);
>> +  this->e_shnum(0);
>> +  this->e_shstrndx(0);
>> +}
>> +
>> +template< support::endianness target_endianness,
>> +         bool is64Bits>
>> +StringRef ELFHeaderChunk<target_endianness,is64Bits>
>> +                        ::segmentName() const {
>> +  return StringRef("ELF");
>> +}
>> +
>> +template< support::endianness target_endianness,
>> +         bool is64Bits>
>> +void ELFHeaderChunk<target_endianness,is64Bits>
>> +                   ::write(uint8_t *chunkBuffer) {
>> +  ::memcpy (chunkBuffer, &this->_eh, this->size());
>
> No space before (
>
>> +}
>> +
>> +template< support::endianness target_endianness,
>> +         bool is64Bits>
>> +const char* ELFHeaderChunk<target_endianness,is64Bits>
>> +                          ::info() {
>> +  return "elf_header";
>> +}
>> +
>> +template< support::endianness target_endianness,
>> +          bool is64Bits>
>> +uint32_t ELFHeaderChunk<target_endianness,is64Bits>
>> +                       ::filetype(WriterOptionsELF::OutputKind kind) {
>> +  switch ( kind ) {
>> +    case WriterOptionsELF::outputDynamicExecutable:
>> +    case WriterOptionsELF::outputStaticExecutable:
>> +      return ELF::ET_EXEC;
>> +    case WriterOptionsELF::outputDylib:
>> +      return ELF::ET_DYN;
>> +    case WriterOptionsELF::outputObjectFile:
>> +      return ELF::ET_REL;
>> +  }
>> +  assert(0 && "file outputkind not supported");
>
> Use llvm_unreachable.
>
>> +}
>> +
>> +//===----------------------------------------------------------------------===//
>> +//  ELFSectionHeaderChunk
>> +//  List of Section Headers:
>> +//[Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
>> +//[ 0]                   NULL            00000000 000000 000000 00      0   0  0
>> +//[ 1] .text             PROGBITS        00000000 000034 000040 00  AX  0   0  4
>> +//===----------------------------------------------------------------------===//
>> +template<support::endianness target_endianness, bool is64Bits>
>> +ELFSectionHeaderChunk<target_endianness,is64Bits>
>> +              ::ELFSectionHeaderChunk(const WriterOptionsELF& options,
>> +                                      class ELFWriter<target_endianness, is64Bits>&
>> +                                      writer)
>> +    : _options(options)
>> +    , _writer(writer) {
>> +
>> +  this->_size = 0;
>> +  this->_align2 = 0;
>> +//
>> +// The first element in the list is always NULL
>> +//
>> +    Elf_Shdr *nullShdr = new Elf_Shdr;
>
> Who deletes this? Can we use unique_ptr?
>
>> +    ::memset((void *)nullShdr, 0, sizeof (Elf_Shdr));
>> +    _sectionInfo.push_back (nullShdr);
>> +
>> +    this->_size += sizeof (Elf_Shdr);
>> +//TODO : implement strtab and shstrtab
>> +//khemant
>> +  Elf_Shdr *shdr ;
>> +  ELFStringSectionChunk<target_endianness,is64Bits> *str = _writer.shstrtab();
>> +  std::vector<SectionChunk<target_endianness,is64Bits>*>
>> +              sections = _writer.sectionChunks();
>
> You can use auto here.
>
>> +
>> +  typename  std::vector<SectionChunk<target_endianness,is64Bits>*>::iterator
>> +                        si = sections.begin();
>> +  typename  std::vector<SectionChunk<target_endianness,is64Bits>*>::iterator
>> +                        se = sections.end();
>> +
>> +
>> +
>> +  for ( ; si != se ; ++si) {
>
> For range.
>
>> +     shdr = new Elf_Shdr;
>
> Ownership?
>
>> +     StringRef name = (*si)->sectionName();
>> +     uint64_t offset = str->addString(name);
>> +     shdr->sh_name = offset;
>> +     shdr->sh_type = (*si)->type();
>> +     shdr->sh_flags = (*si)->flags();
>> + // TODO: At the time of creation of this section header, we will not have any
>> + // address and offset info. We  revisit this after assigning the file
>> + // offsets
>> +     shdr->sh_offset = (*si)->fileOffset();
>> +     shdr->sh_addr = (*si)->address();
>> +     shdr->sh_size = (*si)->size();
>> +// The next two fields have special meanings:
>> +// sh_type           sh_link                             sh_info
>> +// SHT_DYNAMIC  The section header index of the string
>> +//                table used by entries in the section.   0
>> +// SHT_HASH     The section header index of the symbol
>> +//                table to which the hash table applies.  0
>> +// SHT_REL
>> +// SHT_RELA     The section header index of the
>> +//                associated symbol table.                The section header
>> +//                                                        index of the section
>> +//                                                        to which the relocation
>> +//                                                        applies.
>> +// SHT_SYMTAB
>> +// SHT_DYNSYM   The section header index of the
>> +//                associated string table.                One greater than the
>> +//                                                        symbol table index of
>> +//                                                        the last local symbol
>> +//                                                        (binding STB_LOCAL).
>> +// SHT_GROUP    The section header index of the
>> +//              associated symbol table.                  The symbol table
>> +//                                                        index of an entry in
>> +//                                                        the associated symbol
>> +//                                                        table. The name of
>> +//                                                        the specified symbol
>> +//                                                        table entry provides
>> +//                                                        a signature for the
>> +//                                                        section group.
>> +// SHT_SYMTAB_SHNDX The section header index of
>> +//                  the associated symbol table section.  0
>> +// None of these chunks are of the above mentioned type, so we short them.
>> +     shdr->sh_link = 0;
>> +     shdr->sh_info = 0;
>> +     shdr->sh_addralign = (*si)->align2();
>> +// Not a special section with fixed entries
>> +     shdr->sh_entsize = 0;
>> +
>> +     _sectionInfo.push_back(shdr);
>> +    this->_size += sizeof (Elf_Shdr);
>> +  }
>> +
>> +// Now I add in the section string table. For some reason This seems to be
>> +// preferred location of string sectiosn in contemporary
>> +// (ones that must not be named) linker(s).
>> +  shdr = new Elf_Shdr;
>
> Ownership?
>
>> +// I push the name of the string table into the string table as soon as
>> +// it is created
>> +  shdr->sh_name = 1;
>> +  shdr->sh_type = ELF::SHT_STRTAB;
>> +  shdr->sh_flags = 0;
>> +// NOTE: Refer to above note when assigning st_addr for other sections
>> +  shdr->sh_addr = str->address();
>> +  shdr->sh_offset = str->fileOffset();
>> +  shdr->sh_size = str->size();
>> +  shdr->sh_link = 0;
>> +  shdr->sh_info = 0;
>> +// THis section is not a loadable section, hence we do not care about alignment
>> +  shdr->sh_addralign = 1;
>> +  _sectionInfo.push_back(shdr);
>> +  this->_size += sizeof (Elf_Shdr);
>> +
>> +
>> +
>
> Useless whitespace.
>
>> +}
>> +
>> +template<support::endianness target_endianness, bool is64Bits>
>> +StringRef ELFSectionHeaderChunk<target_endianness,is64Bits>::segmentName()
>> +          const {
>> +  return StringRef("SHDR");
>> +}
>> +
>> +template<support::endianness target_endianness, bool is64Bits>
>> +void ELFSectionHeaderChunk<target_endianness,is64Bits>::write(
>> +                                                    uint8_t *chunkBuffer) {
>> +    for (auto si =this->_sectionInfo.begin(), se = this->_sectionInfo.end();
>> +         si != se; ++si) {
>
> For range.
>
>> +
>> +      Elf_Shdr *shdr = (*si);
>> +      ::memcpy(chunkBuffer,
>> +               shdr,
>> +               sizeof (Elf_Shdr));
>> +      chunkBuffer += sizeof (Elf_Shdr);
>> +    }
>
> Indent 2 spaces.
>
>> +}
>> +
>> +template<support::endianness target_endianness, bool is64Bits>
>> +uint16_t ELFSectionHeaderChunk<target_endianness,is64Bits>::count() {
>> +    return _sectionInfo.size();
>> +}
>> +template<support::endianness target_endianness, bool is64Bits>
>> +uint16_t ELFSectionHeaderChunk<target_endianness,is64Bits>::size() {
>> +    return sizeof (Elf_Shdr);
>> +}
>> +
>> +template<support::endianness target_endianness, bool is64Bits>
>> +const char* ELFSectionHeaderChunk<target_endianness,is64Bits>::info() {
>> +  return "elf_section_header";
>> +}
>> +
>> +
>> +//===----------------------------------------------------------------------===//
>> +//  ELFProgramHeaderChunk
>> +//===----------------------------------------------------------------------===//
>> +// TODO: Implement the methods
>> +
>> +//===----------------------------------------------------------------------===//
>> +//  ELFWriter Class
>> +//===----------------------------------------------------------------------===//
>> +template <support::endianness target_endianness, bool is64Bits>
>> +class ELFWriter : public Writer {
>> +public:
>> +  LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
>> +  typedef object::Elf_Shdr_Impl<target_endianness, is64Bits> Elf_Shdr;
>> +  ELFWriter(const WriterOptionsELF &options);
>> +  virtual error_code  writeFile(const lld::File &file, StringRef path);
>> +  const std::vector<Chunk<target_endianness,
>> +                          is64Bits> * > chunks() { return _chunks; }
>> +  KindHandler *kindHandler() { return _referenceKindHandler; }
>> +  std::vector<SectionChunk<target_endianness,
>> +              is64Bits> * > sectionChunks() { return _sectionChunks ; }
>> +   ELFStringSectionChunk<target_endianness,is64Bits> *shstrtab()
>> +                                                   {return shstrtable;}
>> +
>> +private:
>> +  void build (const lld::File &file);
>> +  void createChunks (const lld::File &file);
>
> Why File instead of ELFFile?
>
>> +  void assignFileOffsets();
>> +  const WriterOptionsELF &_options;
>> +  ELFStringSectionChunk<target_endianness,is64Bits> *shstrtable ;
>> +  KindHandler *_referenceKindHandler;
>> +  class ELFSectionHeaderChunk<target_endianness,is64Bits> *_sectionHeaderChunk;
>> +  std::vector<Chunk<target_endianness,is64Bits> * > _chunks;
>> +  const DefinedAtom *_entryAtom;
>> +  std::vector<SectionChunk<target_endianness,is64Bits> * > _sectionChunks;
>> +};
>> +
>> +
>> +//===----------------------------------------------------------------------===//
>> +//  ELFWriter
>> +//===----------------------------------------------------------------------===//
>> +template <support::endianness target_endianness, bool is64Bits>
>> +ELFWriter<target_endianness,is64Bits>::ELFWriter
>> +                                    (const WriterOptionsELF &options)
>> +  : _options(options),
>> +    _referenceKindHandler(KindHandler::makeHandler(_options.architecture()))
>> +{}
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +void ELFWriter<target_endianness,is64Bits>::build(const lld::File &file)
>> +{
>> +  // Create objects for each chunk.
>> +  this->createChunks(file);
>> +
>> +  this->assignFileOffsets();
>> +}
>> +
>> +
>> +// Creating chunks is a delicate dance in ELF.
>> +// 1. ELF Header
>> +// 2. Section Header table
>> +// 3. String Section (we need this for putting in sh_name member
>> +// 4. All the stock sections
>> +// 5. Section String section
>> +// 6. String section
>> +// 7. Symbol section
>> +// The above sequence is usually what an ELF section layout looks like.
>> +// Since the _chunks vector has all these chunks, we need to be careful with
>> +// this sequence when we actually do file offset assignment
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +void ELFWriter<target_endianness,is64Bits>::createChunks(const lld::File &file){
>> +  std::map<DefinedAtom::ContentType,
>> +            SectionChunk<target_endianness,is64Bits>* > map;
>
> What is this for (comment)?
>
>> +  ELFHeaderChunk<target_endianness,is64Bits>*ehc;
>
> Space after , and before *.
>
>> +
>> +// We need to create hand crafted sections such as
>> +// shstrtab strtab hash and symtab to put relevant information in
>> +// ELF structures and then process the atoms
>> +
>> +  shstrtable = new  ELFStringSectionChunk<target_endianness,is64Bits>
>> +                             (_options,*this,StringRef("shstrtab"));
>
> Ownership?
>
>> +   shstrtable->addString(StringRef("shstrtab"));
>> +  //uint64_t ShstrtabOffset = shstrtable->addString(StringRef("shstrtab"));
>> +
>> +
>> +//we also need to process undefined atoms
>> +  for (const DefinedAtom* atom : file.defined() ) {
>> +    // TODO: Add sectionChoice.
>> +    // assert( atom->sectionChoice() == DefinedAtom::sectionBasedOnContent );
>> +    DefinedAtom::ContentType type = atom->contentType();
>> +    auto pos = map.find(type);
>> +    if (pos == map.end()) {
>> +      StringRef sectionName = atom->customSectionName();
>> +      SectionChunk<target_endianness,is64Bits>
>> +                  *chunk = new SectionChunk<target_endianness,is64Bits>
>> +                                   (type, sectionName, _options, *this);
>> +      if (chunk->type() != ELF::SHT_NULL ) {
>> +        map[type] = chunk;
>> +        chunk->appendAtom(atom);
>> +        _sectionChunks.push_back(chunk);
>> +      }
>> +    }
>> +    else {
>> +      pos->second->appendAtom(atom);
>> +    }
>
> What is this code doing?
>
>> +    //printf ("Atom Name: %s\n", atom->name().data());
>> +  }
>> +
>> +  //put in the Undefined atoms as well
>> +
>> +  // Make header chunk
>> +    ehc =
>> +      new ELFHeaderChunk<target_endianness,is64Bits>
>> +        (_options, file);
>> +
>> +    _sectionHeaderChunk =
>> +    new ELFSectionHeaderChunk<target_endianness,is64Bits>( _options, *this);
>
> Ownership?
>
>> +
>> +    ehc->e_shoff(ehc->size());
>> +    ehc->e_shentsize(_sectionHeaderChunk->size());
>> +    ehc->e_shnum(_sectionHeaderChunk->count());
>> +
>> + // I am pushign string section after all sections are in.
>
> pushing
>
>> + // Hence the index will be total number of non-custom sections we have
>> +
>> +    ehc->e_shstrndx(_sectionChunks.size() + 1);
>> +    _chunks.push_back(ehc);
>> +    _chunks.push_back(_sectionHeaderChunk);
>> +// We have ELF header, section header. Now push rest of sections
>> +    for (auto chnk : _sectionChunks)
>> +        _chunks.push_back(chnk);
>> +    _chunks.push_back(shstrtable);
>> +
>> +}
>> +
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +void ELFWriter<target_endianness,is64Bits>::assignFileOffsets() {
>> +  DEBUG_WITH_TYPE("WriterELF-layout", dbgs()
>> +                    << "assign file offsets:\n");
>> +  uint64_t offset = 0;
>> +  uint64_t address = 0;
>> +  for ( Chunk<target_endianness,is64Bits> *chunk : _chunks ) {
>> +// FIXME: A __LINKEDIT segment is similar to PT_DYNAMIC segment in ELF?
>> +//        I don't see any special alignment requirements however.
>> +#if 0
>> +    if ( chunk->segmentName().equals("__LINKEDIT") ) {
>> +      _linkEditStartOffset  = Chunk::alignTo(offset, 12);
>> +      _linkEditStartAddress = Chunk::alignTo(address, 12);
>> +      break;
>> +    }
>> +#endif
>> +    chunk->assignFileOffset(offset, address);
>> +  }
>> +//TODO: We need to fix all file offsets inside various ELF section headers
>> +  std::vector<Elf_Shdr*>SecInfo = _sectionHeaderChunk->sectionInfo();
>> +  typename std::vector<Elf_Shdr*>::iterator it = SecInfo.begin();
>> +// First section is a NULL section with no sh_offset fix
>> +   (*it)->sh_offset = 0;
>> +   (*it)->sh_addr = 0;
>> +   ++it;
>> +  for (auto si=_sectionChunks.begin(), se=_sectionChunks.end();
>> +       si!=se ; ++si){
>> +       (*it)->sh_offset = (*si)->fileOffset();
>> +       (*it)->sh_addr = (*si)->address();
>> +       ++it;
>> +  }
>> +// We  have taken care of  all the stock sections. We need to deal with
>> +// custom sections
>> +// They are section string table, string table and symbol table
>> +  (*it)->sh_offset = shstrtable->fileOffset();
>> +  (*it)->sh_addr = shstrtable->address();
>> +
>> +}
>> +
>> +
>> +template <support::endianness target_endianness, bool is64Bits>
>> +error_code ELFWriter<target_endianness,is64Bits>::writeFile
>> +                                (const lld::File &file, StringRef path) {
>> +  this->build(file);
>> +
>> +  uint64_t totalSize = _chunks.back()->fileOffset() + _chunks.back()->size();
>> +//
>> +// Pulled in from mailing list:
>> +// http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-May/049841.html
>> +// Updated to compile with most recent llvm.
>> +//
>> +  OwningPtr<FileOutputBuffer> buffer;
>> +  error_code ec = FileOutputBuffer::create(path,
>> +                                          totalSize, buffer,
>> +                                          FileOutputBuffer::F_executable);
>> +  if ( ec )
>> +    return ec;
>> +
>> +  for ( Chunk<target_endianness,is64Bits> *chunk : _chunks ) {
>> +    chunk->write(buffer->getBufferStart()+chunk->fileOffset());
>> +  }
>> +  return buffer->commit();
>> +
>> +}
>> +
>> +} // namespace elf
>> +
>> +
>> +Writer* createWriterELF(const WriterOptionsELF &options) {
>> +
>> +
>> +   std::pair<support::endianness,bool> archType = options.getArchTypeClass();
>> +   if (archType.first == support::little && archType.second == false)
>> +    return new lld::elf::ELFWriter<support::little,false>(options);
>> +   else if (archType.first == support::little && archType.second == true)
>> +    return new lld::elf::ELFWriter<support::little,true>(options);
>> +   if (archType.first == support::big && archType.second == false)
>> +    return new lld::elf::ELFWriter<support::big,false>(options);
>> +   else if (archType.first == support::big && archType.second == true)
>> +    return new lld::elf::ELFWriter<support::big,true>(options);
>> +
>> +    return nullptr;
>> +}
>
> Needs proper whitespace and ownership semantics.
>
>>  } // namespace lld
>> -
>> Index: lib/ReaderWriter/ELF/ReferenceKinds.cpp
>> ===================================================================
>> --- lib/ReaderWriter/ELF/ReferenceKinds.cpp   (revision 0)
>> +++ lib/ReaderWriter/ELF/ReferenceKinds.cpp   (revision 0)
>> @@ -0,0 +1,172 @@
>> +//===- lib/ReaderWriter/ELF/ReferenceKinds.cpp ----------------------------===//
>> +//
>> +//                             The LLVM Linker
>> +//
>> +// This file is distributed under the University of Illinois Open Source
>> +// License. See LICENSE.TXT for details.
>> +//
>> +//===----------------------------------------------------------------------===//
>> +
>> +
>> +#include "ReferenceKinds.h"
>> +
>> +#include "llvm/ADT/StringRef.h"
>> +#include "llvm/ADT/StringSwitch.h"
>> +
>> +#include "llvm/Support/ErrorHandling.h"
>> +
>> +namespace lld {
>> +namespace elf {
>> +
>> +//===----------------------------------------------------------------------===//
>> +//  KindHandler
>> +//===----------------------------------------------------------------------===//
>> +
>> +KindHandler::KindHandler() {
>> +}
>> +
>> +KindHandler::~KindHandler() {
>> +}
>> +
>> +KindHandler *KindHandler::makeHandler(WriterOptionsELF::Architecture arch) {
>
> Who owns the return value?
>
>> +  switch( arch ) {
>> +    case WriterOptionsELF::arch_hexagon:
>> +      return new KindHandler_hexagon();
>> +    case WriterOptionsELF::arch_x86:
>> +      return new KindHandler_x86();
>> +    default:
>> +      assert(0 && "arch not supported");
>
> llvm_unreachable. Although should be a proper diagnostic when we have them.
>
>> +  }
>> +}
>> +
>> +//===----------------------------------------------------------------------===//
>> +//  KindHandler_x86
>> +//  TODO: more to do here
>> +//===----------------------------------------------------------------------===//
>> +
>> +KindHandler_x86::~KindHandler_x86() {
>> +}
>> +
>> +Reference::Kind KindHandler_x86::stringToKind(StringRef str) {
>> +  return llvm::StringSwitch<Reference::Kind>(str)
>> +    .Case("none",                  none)
>> +    .Default(invalid);
>> +
>> +  llvm_unreachable("invalid x86 Reference kind");
>> +}
>> +
>> +StringRef KindHandler_x86::kindToString(Reference::Kind kind) {
>> +  switch ( (Kinds)kind ) {
>> +    case invalid:
>> +      return StringRef("invalid");
>> +    case none:
>> +      return StringRef("none");
>> +  }
>> +  llvm_unreachable("invalid x86 Reference kind");
>> +}
>> +
>> +bool KindHandler_x86::isCallSite(Kind kind) {
>> +  llvm_unreachable("Unimplemented: KindHandler_x86::isCallSite");
>> +  return false;
>> +}
>> +
>> +bool KindHandler_x86::isPointer(Kind kind) {
>> +  llvm_unreachable("Unimplemented: KindHandler_x86::isPointer");
>> +  return false;
>> +}
>> +
>> +bool KindHandler_x86::isLazyImmediate(Kind kind) {
>> +  llvm_unreachable("Unimplemented: KindHandler_x86::isLazyImmediate");
>> +  return false;
>> +}
>> +
>> +bool KindHandler_x86::isLazyTarget(Kind kind) {
>> +  llvm_unreachable("Unimplemented: KindHandler_x86::isLazyTarget");
>> +  return false;
>> +}
>> +
>> +
>> +void KindHandler_x86::applyFixup(Kind kind, uint64_t addend,
>> +                                    uint8_t *location, uint64_t fixupAddress,
>> +                                    uint64_t targetAddress) {
>> +  int32_t *loc32 = reinterpret_cast<int32_t*>(location);
>> +  uint64_t *loc64 = reinterpret_cast<uint64_t*>(location);
>> +  switch ( (Kinds)kind ) {
>> +    case none:
>> +      // do nothing
>> +      break;
>> +    case invalid:
>> +      assert(0 && "invalid Reference Kind");
>> +      break;
>> +  }
>> +}
>> +
>> +//===----------------------------------------------------------------------===//
>> +//  KindHandler_hexagon
>> +//  TODO: more to do here
>> +//===----------------------------------------------------------------------===//
>> +
>> +KindHandler_hexagon::~KindHandler_hexagon() {
>> +}
>> +
>> +Reference::Kind KindHandler_hexagon::stringToKind(StringRef str) {
>> +  return llvm::StringSwitch<Reference::Kind>(str)
>> +    .Case("none",                  none)
>> +    .Default(invalid);
>> +
>> +  llvm_unreachable("invalid hexagon Reference kind");
>> +}
>> +
>> +StringRef KindHandler_hexagon::kindToString(Reference::Kind kind) {
>> +  switch ( (Kinds)kind ) {
>> +    case invalid:
>> +      return StringRef("invalid");
>> +    case none:
>> +      return StringRef("none");
>> +  }
>> +  llvm_unreachable("invalid hexagon Reference kind");
>> +}
>> +
>> +bool KindHandler_hexagon::isCallSite(Kind kind) {
>> +  llvm_unreachable("Unimplemented: KindHandler_hexagon::isCallSite");
>> +  return false;
>> +}
>> +
>> +bool KindHandler_hexagon::isPointer(Kind kind) {
>> +  llvm_unreachable("Unimplemented: KindHandler_hexagon::isPointer");
>> +  return false;
>> +}
>> +
>> +bool KindHandler_hexagon::isLazyImmediate(Kind kind) {
>> +  llvm_unreachable("Unimplemented: KindHandler_hexagon::isLazyImmediate");
>> +  return false;
>> +}
>> +
>> +bool KindHandler_hexagon::isLazyTarget(Kind kind) {
>> +  llvm_unreachable("Unimplemented: KindHandler_hexagon::isLazyTarget");
>> +  return false;
>> +}
>> +
>> +
>> +void KindHandler_hexagon::applyFixup(Kind kind, uint64_t addend,
>> +                                    uint8_t *location, uint64_t fixupAddress,
>> +                                    uint64_t targetAddress) {
>> +  int32_t *loc32 = reinterpret_cast<int32_t*>(location);
>> +  uint64_t *loc64 = reinterpret_cast<uint64_t*>(location);
>> +  switch ( (Kinds)kind ) {
>> +    case none:
>> +      // do nothing
>> +      break;
>> +    case invalid:
>> +      assert(0 && "invalid Reference Kind");
>> +      break;
>> +  }
>> +}
>> +
>> +
>> +
>> +} // namespace elf
>> +} // namespace lld
>> +
>> +
>> +
>> Index: lib/ReaderWriter/ELF/ReaderELF.cpp
>> ===================================================================
>> --- lib/ReaderWriter/ELF/ReaderELF.cpp        (revision 163142)
>> +++ lib/ReaderWriter/ELF/ReaderELF.cpp        (working copy)
>> @@ -214,7 +214,11 @@
>>        return (Alignment(Symbol->st_value));
>>      }
>>
>> -    return Alignment(1);
>> +    return Alignment(llvm::Log2_64(Section->sh_addralign));
>> +//      return (Alignment(llvm::Log2_32(Symbol->st_value)));
>> +//    }
>> +//
>> +//    return Alignment(llvm::Log2_32(Section->sh_addralign));
>
> What is this change doing?
>
>>    }
>>
>>    // Do we have a choice for ELF?  All symbols
>> Index: lib/ReaderWriter/ELF/CMakeLists.txt
>> ===================================================================
>> --- lib/ReaderWriter/ELF/CMakeLists.txt       (revision 163142)
>> +++ lib/ReaderWriter/ELF/CMakeLists.txt       (working copy)
>> @@ -1,4 +1,6 @@
>>  add_lld_library(lldELF
>>    ReaderELF.cpp
>>    WriterELF.cpp
>> +  ReferenceKinds.cpp
>> +  WriterOptionsELF.cpp
>>    )
>> Index: lib/ReaderWriter/ELF/ReferenceKinds.h
>> ===================================================================
>> --- lib/ReaderWriter/ELF/ReferenceKinds.h     (revision 0)
>> +++ lib/ReaderWriter/ELF/ReferenceKinds.h     (revision 0)
>> @@ -0,0 +1,93 @@
>> +//===- lib/ReaderWriter/ELF/ReferenceKinds.h ------------------------------===//
>> +//
>> +//                             The LLVM Linker
>> +//
>> +// This file is distributed under the University of Illinois Open Source
>> +// License. See LICENSE.TXT for details.
>> +//
>> +//===----------------------------------------------------------------------===//
>> +
>> +
>> +#include "lld/Core/LLVM.h"
>> +#include "lld/Core/Reference.h"
>> +#include "lld/ReaderWriter/WriterELF.h"
>> +
>> +#ifndef LLD_READER_WRITER_ELF_REFERENCE_KINDS_H_
>> +#define LLD_READER_WRITER_ELF_REFERENCE_KINDS_H_
>> +
>> +namespace lld {
>> +namespace elf {
>> +
>> +
>> +///
>> +/// The KindHandler class is the abstract interface to Reference::Kind
>> +/// values for ELF files.  Particular Kind values (e.g. 3) has a different
>> +/// meaning for each architecture.
>> +/// TODO: Needs to be updated for ELF, stubs for now.
>> +///
>> +class KindHandler {
>> +public:
>> +  typedef Reference::Kind Kind;
>> +
>> +  static KindHandler *makeHandler(WriterOptionsELF::Architecture arch);
>> +  virtual             ~KindHandler();
>> +  virtual Kind        stringToKind(StringRef str) = 0;
>> +  virtual StringRef   kindToString(Kind) = 0;
>> +  virtual bool        isCallSite(Kind) = 0;
>> +  virtual bool        isPointer(Kind) = 0;
>> +  virtual bool        isLazyImmediate(Kind) = 0;
>> +  virtual bool        isLazyTarget(Kind) = 0;
>> +  virtual void        applyFixup(Kind kind, uint64_t addend, uint8_t *location,
>> +                           uint64_t fixupAddress, uint64_t targetAddress) = 0;
>> +
>> +protected:
>> +  KindHandler();
>> +};
>> +
>> +
>> +class KindHandler_hexagon : public KindHandler {
>> +public:
>> +  enum Kinds {
>> +    invalid,         // used to denote an error creating a Reference
>> +    none,
>> +  };
>> +
>> +  virtual ~KindHandler_hexagon();
>> +  virtual Kind stringToKind(StringRef str);
>> +  virtual StringRef kindToString(Kind);
>> +  virtual bool isCallSite(Kind);
>> +  virtual bool isPointer(Kind);
>> +  virtual bool isLazyImmediate(Kind);
>> +  virtual bool isLazyTarget(Kind);
>> +  virtual void applyFixup(Kind kind, uint64_t addend, uint8_t *location,
>> +                  uint64_t fixupAddress, uint64_t targetAddress);
>> +
>> +};
>> +
>> +
>> +class KindHandler_x86 : public KindHandler {
>> +public:
>> +  enum Kinds {
>> +    invalid,         // used to denote an error creating a Reference
>> +    none,
>> +  };
>> +
>> +  virtual ~KindHandler_x86();
>> +  virtual Kind stringToKind(StringRef str);
>> +  virtual StringRef kindToString(Kind);
>> +  virtual bool isCallSite(Kind);
>> +  virtual bool isPointer(Kind);
>> +  virtual bool isLazyImmediate(Kind);
>> +  virtual bool isLazyTarget(Kind);
>> +  virtual void applyFixup(Kind kind, uint64_t addend, uint8_t *location,
>> +                  uint64_t fixupAddress, uint64_t targetAddress);
>> +
>> +};
>> +
>> +} // namespace elf
>> +} // namespace lld
>> +
>> +
>> +
>> +#endif // LLD_READER_WRITER_ELF_REFERENCE_KINDS_H_
>> +
>>
>
> - Michael Spencer

LLVM changes committed.

Attached is your patch with a bunch of cleanups (mostly whitespace and
capitalization, but also some structural changes). Some of the
cleanups may not have been directly from code you added. I've also
attached a diff from your patch to my patch.

Also, this needs test cases. Using llvm-objdump or elf-dump.py is fine for now.

- Michael Spencer
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