gold/arm.cc

// arm.cc -- arm target support for gold.

// Copyright (C) 2009-2021 Free Software Foundation, Inc.
// Written by Doug Kwan <dougkwan@google.com> based on the i386 code
// by Ian Lance Taylor <iant@google.com>.
// This file also contains borrowed and adapted code from
// bfd/elf32-arm.c.

// This file is part of gold.

// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.

#include "gold.h"

#include <cstring>
#include <limits>
#include <cstdio>
#include <string>
#include <algorithm>
#include <map>
#include <utility>
#include <set>

#include "elfcpp.h"
#include "parameters.h"
#include "reloc.h"
#include "arm.h"
#include "object.h"
#include "symtab.h"
#include "layout.h"
#include "output.h"
#include "copy-relocs.h"
#include "target.h"
#include "target-reloc.h"
#include "target-select.h"
#include "tls.h"
#include "defstd.h"
#include "gc.h"
#include "attributes.h"
#include "arm-reloc-property.h"
#include "nacl.h"

namespace
{

using namespace gold;

template<bool big_endian>
class Output_data_plt_arm;

template<bool big_endian>
class Output_data_plt_arm_short;

template<bool big_endian>
class Output_data_plt_arm_long;

template<bool big_endian>
class Stub_table;

template<bool big_endian>
class Arm_input_section;

class Arm_exidx_cantunwind;

class Arm_exidx_merged_section;

class Arm_exidx_fixup;

template<bool big_endian>
class Arm_output_section;

class Arm_exidx_input_section;

template<bool big_endian>
class Arm_relobj;

template<bool big_endian>
class Arm_relocate_functions;

template<bool big_endian>
class Arm_output_data_got;

template<bool big_endian>
class Target_arm;

// For convenience.
typedef elfcpp::Elf_types<32>::Elf_Addr Arm_address;

// Maximum branch offsets for ARM, THUMB and THUMB2.
const int32_t ARM_MAX_FWD_BRANCH_OFFSET = ((((1 << 23) - 1) << 2) + 8);
const int32_t ARM_MAX_BWD_BRANCH_OFFSET = ((-((1 << 23) << 2)) + 8);
const int32_t THM_MAX_FWD_BRANCH_OFFSET = ((1 << 22) -2 + 4);
const int32_t THM_MAX_BWD_BRANCH_OFFSET = (-(1 << 22) + 4);
const int32_t THM2_MAX_FWD_BRANCH_OFFSET = (((1 << 24) - 2) + 4);
const int32_t THM2_MAX_BWD_BRANCH_OFFSET = (-(1 << 24) + 4);

// Thread Control Block size.
const size_t ARM_TCB_SIZE = 8;

// The arm target class.
//
// This is a very simple port of gold for ARM-EABI.  It is intended for
// supporting Android only for the time being.
//
// TODOs:
// - Implement all static relocation types documented in arm-reloc.def.
// - Make PLTs more flexible for different architecture features like
//   Thumb-2 and BE8.
// There are probably a lot more.

// Ideally we would like to avoid using global variables but this is used
// very in many places and sometimes in loops.  If we use a function
// returning a static instance of Arm_reloc_property_table, it will be very
// slow in an threaded environment since the static instance needs to be
// locked.  The pointer is below initialized in the
// Target::do_select_as_default_target() hook so that we do not spend time
// building the table if we are not linking ARM objects.
//
// An alternative is to process the information in arm-reloc.def in
// compilation time and generate a representation of it in PODs only.  That
// way we can avoid initialization when the linker starts.

Arm_reloc_property_table* arm_reloc_property_table = NULL;

// Instruction template class.  This class is similar to the insn_sequence
// struct in bfd/elf32-arm.c.

class Insn_template
{
 public:
  // Types of instruction templates.
  enum Type
    {
      THUMB16_TYPE = 1,
      // THUMB16_SPECIAL_TYPE is used by sub-classes of Stub for instruction
      // templates with class-specific semantics.  Currently this is used
      // only by the Cortex_a8_stub class for handling condition codes in
      // conditional branches.
      THUMB16_SPECIAL_TYPE,
      THUMB32_TYPE,
      ARM_TYPE,
      DATA_TYPE
    };

  // Factory methods to create instruction templates in different formats.

  static const Insn_template
  thumb16_insn(uint32_t data)
  { return Insn_template(data, THUMB16_TYPE, elfcpp::R_ARM_NONE, 0); }

  // A Thumb conditional branch, in which the proper condition is inserted
  // when we build the stub.
  static const Insn_template
  thumb16_bcond_insn(uint32_t data)
  { return Insn_template(data, THUMB16_SPECIAL_TYPE, elfcpp::R_ARM_NONE, 1); }

  static const Insn_template
  thumb32_insn(uint32_t data)
  { return Insn_template(data, THUMB32_TYPE, elfcpp::R_ARM_NONE, 0); }

  static const Insn_template
  thumb32_b_insn(uint32_t data, int reloc_addend)
  {
    return Insn_template(data, THUMB32_TYPE, elfcpp::R_ARM_THM_JUMP24,
			 reloc_addend);
  }

  static const Insn_template
  arm_insn(uint32_t data)
  { return Insn_template(data, ARM_TYPE, elfcpp::R_ARM_NONE, 0); }

  static const Insn_template
  arm_rel_insn(unsigned data, int reloc_addend)
  { return Insn_template(data, ARM_TYPE, elfcpp::R_ARM_JUMP24, reloc_addend); }

  static const Insn_template
  data_word(unsigned data, unsigned int r_type, int reloc_addend)
  { return Insn_template(data, DATA_TYPE, r_type, reloc_addend); }

  // Accessors.  This class is used for read-only objects so no modifiers
  // are provided.

  uint32_t
  data() const
  { return this->data_; }

  // Return the instruction sequence type of this.
  Type
  type() const
  { return this->type_; }

  // Return the ARM relocation type of this.
  unsigned int
  r_type() const
  { return this->r_type_; }

  int32_t
  reloc_addend() const
  { return this->reloc_addend_; }

  // Return size of instruction template in bytes.
  size_t
  size() const;

  // Return byte-alignment of instruction template.
  unsigned
  alignment() const;

 private:
  // We make the constructor private to ensure that only the factory
  // methods are used.
  inline
  Insn_template(unsigned data, Type type, unsigned int r_type, int reloc_addend)
    : data_(data), type_(type), r_type_(r_type), reloc_addend_(reloc_addend)
  { }

  // Instruction specific data.  This is used to store information like
  // some of the instruction bits.
  uint32_t data_;
  // Instruction template type.
  Type type_;
  // Relocation type if there is a relocation or R_ARM_NONE otherwise.
  unsigned int r_type_;
  // Relocation addend.
  int32_t reloc_addend_;
};

// Macro for generating code to stub types. One entry per long/short
// branch stub

#define DEF_STUBS \
  DEF_STUB(long_branch_any_any) \
  DEF_STUB(long_branch_v4t_arm_thumb) \
  DEF_STUB(long_branch_thumb_only) \
  DEF_STUB(long_branch_v4t_thumb_thumb) \
  DEF_STUB(long_branch_v4t_thumb_arm) \
  DEF_STUB(short_branch_v4t_thumb_arm) \
  DEF_STUB(long_branch_any_arm_pic) \
  DEF_STUB(long_branch_any_thumb_pic) \
  DEF_STUB(long_branch_v4t_thumb_thumb_pic) \
  DEF_STUB(long_branch_v4t_arm_thumb_pic) \
  DEF_STUB(long_branch_v4t_thumb_arm_pic) \
  DEF_STUB(long_branch_thumb_only_pic) \
  DEF_STUB(a8_veneer_b_cond) \
  DEF_STUB(a8_veneer_b) \
  DEF_STUB(a8_veneer_bl) \
  DEF_STUB(a8_veneer_blx) \
  DEF_STUB(v4_veneer_bx)

// Stub types.

#define DEF_STUB(x) arm_stub_##x,
typedef enum
  {
    arm_stub_none,
    DEF_STUBS

    // First reloc stub type.
    arm_stub_reloc_first = arm_stub_long_branch_any_any,
    // Last  reloc stub type.
    arm_stub_reloc_last = arm_stub_long_branch_thumb_only_pic,

    // First Cortex-A8 stub type.
    arm_stub_cortex_a8_first = arm_stub_a8_veneer_b_cond,
    // Last Cortex-A8 stub type.
    arm_stub_cortex_a8_last = arm_stub_a8_veneer_blx,

    // Last stub type.
    arm_stub_type_last = arm_stub_v4_veneer_bx
  } Stub_type;
#undef DEF_STUB

// Stub template class.  Templates are meant to be read-only objects.
// A stub template for a stub type contains all read-only attributes
// common to all stubs of the same type.

class Stub_template
{
 public:
  Stub_template(Stub_type, const Insn_template*, size_t);

  ~Stub_template()
  { }

  // Return stub type.
  Stub_type
  type() const
  { return this->type_; }

  // Return an array of instruction templates.
  const Insn_template*
  insns() const
  { return this->insns_; }

  // Return size of template in number of instructions.
  size_t
  insn_count() const
  { return this->insn_count_; }

  // Return size of template in bytes.
  size_t
  size() const
  { return this->size_; }

  // Return alignment of the stub template.
  unsigned
  alignment() const
  { return this->alignment_; }

  // Return whether entry point is in thumb mode.
  bool
  entry_in_thumb_mode() const
  { return this->entry_in_thumb_mode_; }

  // Return number of relocations in this template.
  size_t
  reloc_count() const
  { return this->relocs_.size(); }

  // Return index of the I-th instruction with relocation.
  size_t
  reloc_insn_index(size_t i) const
  {
    gold_assert(i < this->relocs_.size());
    return this->relocs_[i].first;
  }

  // Return the offset of the I-th instruction with relocation from the
  // beginning of the stub.
  section_size_type
  reloc_offset(size_t i) const
  {
    gold_assert(i < this->relocs_.size());
    return this->relocs_[i].second;
  }

 private:
  // This contains information about an instruction template with a relocation
  // and its offset from start of stub.
  typedef std::pair<size_t, section_size_type> Reloc;

  // A Stub_template may not be copied.  We want to share templates as much
  // as possible.
  Stub_template(const Stub_template&);
  Stub_template& operator=(const Stub_template&);

  // Stub type.
  Stub_type type_;
  // Points to an array of Insn_templates.
  const Insn_template* insns_;
  // Number of Insn_templates in insns_[].
  size_t insn_count_;
  // Size of templated instructions in bytes.
  size_t size_;
  // Alignment of templated instructions.
  unsigned alignment_;
  // Flag to indicate if entry is in thumb mode.
  bool entry_in_thumb_mode_;
  // A table of reloc instruction indices and offsets.  We can find these by
  // looking at the instruction templates but we pre-compute and then stash
  // them here for speed.
  std::vector<Reloc> relocs_;
};

//
// A class for code stubs.  This is a base class for different type of
// stubs used in the ARM target.
//

class Stub
{
 private:
  static const section_offset_type invalid_offset =
    static_cast<section_offset_type>(-1);

 public:
  Stub(const Stub_template* stub_template)
    : stub_template_(stub_template), offset_(invalid_offset)
  { }

  virtual
   ~Stub()
  { }

  // Return the stub template.
  const Stub_template*
  stub_template() const
  { return this->stub_template_; }

  // Return offset of code stub from beginning of its containing stub table.
  section_offset_type
  offset() const
  {
    gold_assert(this->offset_ != invalid_offset);
    return this->offset_;
  }

  // Set offset of code stub from beginning of its containing stub table.
  void
  set_offset(section_offset_type offset)
  { this->offset_ = offset; }

  // Return the relocation target address of the i-th relocation in the
  // stub.  This must be defined in a child class.
  Arm_address
  reloc_target(size_t i)
  { return this->do_reloc_target(i); }

  // Write a stub at output VIEW.  BIG_ENDIAN select how a stub is written.
  void
  write(unsigned char* view, section_size_type view_size, bool big_endian)
  { this->do_write(view, view_size, big_endian); }

  // Return the instruction for THUMB16_SPECIAL_TYPE instruction template
  // for the i-th instruction.
  uint16_t
  thumb16_special(size_t i)
  { return this->do_thumb16_special(i); }

 protected:
  // This must be defined in the child class.
  virtual Arm_address
  do_reloc_target(size_t) = 0;

  // This may be overridden in the child class.
  virtual void
  do_write(unsigned char* view, section_size_type view_size, bool big_endian)
  {
    if (big_endian)
      this->do_fixed_endian_write<true>(view, view_size);
    else
      this->do_fixed_endian_write<false>(view, view_size);
  }

  // This must be overridden if a child class uses the THUMB16_SPECIAL_TYPE
  // instruction template.
  virtual uint16_t
  do_thumb16_special(size_t)
  { gold_unreachable(); }

 private:
  // A template to implement do_write.
  template<bool big_endian>
  void inline
  do_fixed_endian_write(unsigned char*, section_size_type);

  // Its template.
  const Stub_template* stub_template_;
  // Offset within the section of containing this stub.
  section_offset_type offset_;
};

// Reloc stub class.  These are stubs we use to fix up relocation because
// of limited branch ranges.

class Reloc_stub : public Stub
{
 public:
  static const unsigned int invalid_index = static_cast<unsigned int>(-1);
  // We assume we never jump to this address.
  static const Arm_address invalid_address = static_cast<Arm_address>(-1);

  // Return destination address.
  Arm_address
  destination_address() const
  {
    gold_assert(this->destination_address_ != this->invalid_address);
    return this->destination_address_;
  }

  // Set destination address.
  void
  set_destination_address(Arm_address address)
  {
    gold_assert(address != this->invalid_address);
    this->destination_address_ = address;
  }

  // Reset destination address.
  void
  reset_destination_address()
  { this->destination_address_ = this->invalid_address; }

  // Determine stub type for a branch of a relocation of R_TYPE going
  // from BRANCH_ADDRESS to BRANCH_TARGET.  If TARGET_IS_THUMB is set,
  // the branch target is a thumb instruction.  TARGET is used for look
  // up ARM-specific linker settings.
  static Stub_type
  stub_type_for_reloc(unsigned int r_type, Arm_address branch_address,
		      Arm_address branch_target, bool target_is_thumb);

  // Reloc_stub key.  A key is logically a triplet of a stub type, a symbol
  // and an addend.  Since we treat global and local symbol differently, we
  // use a Symbol object for a global symbol and a object-index pair for
  // a local symbol.
  class Key
  {
   public:
    // If SYMBOL is not null, this is a global symbol, we ignore RELOBJ and
    // R_SYM.  Otherwise, this is a local symbol and RELOBJ must non-NULL
    // and R_SYM must not be invalid_index.
    Key(Stub_type stub_type, const Symbol* symbol, const Relobj* relobj,
	unsigned int r_sym, int32_t addend)
      : stub_type_(stub_type), addend_(addend)
    {
      if (symbol != NULL)
	{
	  this->r_sym_ = Reloc_stub::invalid_index;
	  this->u_.symbol = symbol;
	}
      else
	{
	  gold_assert(relobj != NULL && r_sym != invalid_index);
	  this->r_sym_ = r_sym;
	  this->u_.relobj = relobj;
	}
    }

    ~Key()
    { }

    // Accessors: Keys are meant to be read-only object so no modifiers are
    // provided.

    // Return stub type.
    Stub_type
    stub_type() const
    { return this->stub_type_; }

    // Return the local symbol index or invalid_index.
    unsigned int
    r_sym() const
    { return this->r_sym_; }

    // Return the symbol if there is one.
    const Symbol*
    symbol() const
    { return this->r_sym_ == invalid_index ? this->u_.symbol : NULL; }

    // Return the relobj if there is one.
    const Relobj*
    relobj() const
    { return this->r_sym_ != invalid_index ? this->u_.relobj : NULL; }

    // Whether this equals to another key k.
    bool
    eq(const Key& k) const
    {
      return ((this->stub_type_ == k.stub_type_)
	      && (this->r_sym_ == k.r_sym_)
	      && ((this->r_sym_ != Reloc_stub::invalid_index)
		  ? (this->u_.relobj == k.u_.relobj)
		  : (this->u_.symbol == k.u_.symbol))
	      && (this->addend_ == k.addend_));
    }

    // Return a hash value.
    size_t
    hash_value() const
    {
      return (this->stub_type_
	      ^ this->r_sym_
	      ^ gold::string_hash<char>(
		    (this->r_sym_ != Reloc_stub::invalid_index)
		    ? this->u_.relobj->name().c_str()
		    : this->u_.symbol->name())
	      ^ this->addend_);
    }

    // Functors for STL associative containers.
    struct hash
    {
      size_t
      operator()(const Key& k) const
      { return k.hash_value(); }
    };

    struct equal_to
    {
      bool
      operator()(const Key& k1, const Key& k2) const
      { return k1.eq(k2); }
    };

    // Name of key.  This is mainly for debugging.
    std::string
    name() const ATTRIBUTE_UNUSED;

   private:
    // Stub type.
    Stub_type stub_type_;
    // If this is a local symbol, this is the index in the defining object.
    // Otherwise, it is invalid_index for a global symbol.
    unsigned int r_sym_;
    // If r_sym_ is an invalid index, this points to a global symbol.
    // Otherwise, it points to a relobj.  We used the unsized and target
    // independent Symbol and Relobj classes instead of Sized_symbol<32> and
    // Arm_relobj, in order to avoid making the stub class a template
    // as most of the stub machinery is endianness-neutral.  However, it
    // may require a bit of casting done by users of this class.
    union
    {
      const Symbol* symbol;
      const Relobj* relobj;
    } u_;
    // Addend associated with a reloc.
    int32_t addend_;
  };

 protected:
  // Reloc_stubs are created via a stub factory.  So these are protected.
  Reloc_stub(const Stub_template* stub_template)
    : Stub(stub_template), destination_address_(invalid_address)
  { }

  ~Reloc_stub()
  { }

  friend class Stub_factory;

  // Return the relocation target address of the i-th relocation in the
  // stub.
  Arm_address
  do_reloc_target(size_t i)
  {
    // All reloc stub have only one relocation.
    gold_assert(i == 0);
    return this->destination_address_;
  }

 private:
  // Address of destination.
  Arm_address destination_address_;
};

// Cortex-A8 stub class.  We need a Cortex-A8 stub to redirect any 32-bit
// THUMB branch that meets the following conditions:
//
// 1. The branch straddles across a page boundary. i.e. lower 12-bit of
//    branch address is 0xffe.
// 2. The branch target address is in the same page as the first word of the
//    branch.
// 3. The branch follows a 32-bit instruction which is not a branch.
//
// To do the fix up, we need to store the address of the branch instruction
// and its target at least.  We also need to store the original branch
// instruction bits for the condition code in a conditional branch.  The
// condition code is used in a special instruction template.  We also want
// to identify input sections needing Cortex-A8 workaround quickly.  We store
// extra information about object and section index of the code section
// containing a branch being fixed up.  The information is used to mark
// the code section when we finalize the Cortex-A8 stubs.
//

class Cortex_a8_stub : public Stub
{
 public:
  ~Cortex_a8_stub()
  { }

  // Return the object of the code section containing the branch being fixed
  // up.
  Relobj*
  relobj() const
  { return this->relobj_; }

  // Return the section index of the code section containing the branch being
  // fixed up.
  unsigned int
  shndx() const
  { return this->shndx_; }

  // Return the source address of stub.  This is the address of the original
  // branch instruction.  LSB is 1 always set to indicate that it is a THUMB
  // instruction.
  Arm_address
  source_address() const
  { return this->source_address_; }

  // Return the destination address of the stub.  This is the branch taken
  // address of the original branch instruction.  LSB is 1 if it is a THUMB
  // instruction address.
  Arm_address
  destination_address() const
  { return this->destination_address_; }

  // Return the instruction being fixed up.
  uint32_t
  original_insn() const
  { return this->original_insn_; }

 protected:
  // Cortex_a8_stubs are created via a stub factory.  So these are protected.
  Cortex_a8_stub(const Stub_template* stub_template, Relobj* relobj,
		 unsigned int shndx, Arm_address source_address,
		 Arm_address destination_address, uint32_t original_insn)
    : Stub(stub_template), relobj_(relobj), shndx_(shndx),
      source_address_(source_address | 1U),
      destination_address_(destination_address),
      original_insn_(original_insn)
  { }

  friend class Stub_factory;

  // Return the relocation target address of the i-th relocation in the
  // stub.
  Arm_address
  do_reloc_target(size_t i)
  {
    if (this->stub_template()->type() == arm_stub_a8_veneer_b_cond)
      {
	// The conditional branch veneer has two relocations.
	gold_assert(i < 2);
	return i == 0 ? this->source_address_ + 4 : this->destination_address_;
      }
    else
      {
	// All other Cortex-A8 stubs have only one relocation.
	gold_assert(i == 0);
	return this->destination_address_;
      }
  }

  // Return an instruction for the THUMB16_SPECIAL_TYPE instruction template.
  uint16_t
  do_thumb16_special(size_t);

 private:
  // Object of the code section containing the branch being fixed up.
  Relobj* relobj_;
  // Section index of the code section containing the branch begin fixed up.
  unsigned int shndx_;
  // Source address of original branch.
  Arm_address source_address_;
  // Destination address of the original branch.
  Arm_address destination_address_;
  // Original branch instruction.  This is needed for copying the condition
  // code from a condition branch to its stub.
  uint32_t original_insn_;
};

// ARMv4 BX Rx branch relocation stub class.
class Arm_v4bx_stub : public Stub
{
 public:
  ~Arm_v4bx_stub()
  { }

  // Return the associated register.
  uint32_t
  reg() const
  { return this->reg_; }

 protected:
  // Arm V4BX stubs are created via a stub factory.  So these are protected.
  Arm_v4bx_stub(const Stub_template* stub_template, const uint32_t reg)
    : Stub(stub_template), reg_(reg)
  { }

  friend class Stub_factory;

  // Return the relocation target address of the i-th relocation in the
  // stub.
  Arm_address
  do_reloc_target(size_t)
  { gold_unreachable(); }

  // This may be overridden in the child class.
  virtual void
  do_write(unsigned char* view, section_size_type view_size, bool big_endian)
  {
    if (big_endian)
      this->do_fixed_endian_v4bx_write<true>(view, view_size);
    else
      this->do_fixed_endian_v4bx_write<false>(view, view_size);
  }

 private:
  // A template to implement do_write.
  template<bool big_endian>
  void inline
  do_fixed_endian_v4bx_write(unsigned char* view, section_size_type)
  {
    const Insn_template* insns = this->stub_template()->insns();
    elfcpp::Swap<32, big_endian>::writeval(view,
					   (insns[0].data()
					   + (this->reg_ << 16)));
    view += insns[0].size();
    elfcpp::Swap<32, big_endian>::writeval(view,
					   (insns[1].data() + this->reg_));
    view += insns[1].size();
    elfcpp::Swap<32, big_endian>::writeval(view,
					   (insns[2].data() + this->reg_));
  }

  // A register index (r0-r14), which is associated with the stub.
  uint32_t reg_;
};

// Stub factory class.

class Stub_factory
{
 public:
  // Return the unique instance of this class.
  static const Stub_factory&
  get_instance()
  {
    static Stub_factory singleton;
    return singleton;
  }

  // Make a relocation stub.
  Reloc_stub*
  make_reloc_stub(Stub_type stub_type) const
  {
    gold_assert(stub_type >= arm_stub_reloc_first
		&& stub_type <= arm_stub_reloc_last);
    return new Reloc_stub(this->stub_templates_[stub_type]);
  }

  // Make a Cortex-A8 stub.
  Cortex_a8_stub*
  make_cortex_a8_stub(Stub_type stub_type, Relobj* relobj, unsigned int shndx,
		      Arm_address source, Arm_address destination,
		      uint32_t original_insn) const
  {
    gold_assert(stub_type >= arm_stub_cortex_a8_first
		&& stub_type <= arm_stub_cortex_a8_last);
    return new Cortex_a8_stub(this->stub_templates_[stub_type], relobj, shndx,
			      source, destination, original_insn);
  }

  // Make an ARM V4BX relocation stub.
  // This method creates a stub from the arm_stub_v4_veneer_bx template only.
  Arm_v4bx_stub*
  make_arm_v4bx_stub(uint32_t reg) const
  {
    gold_assert(reg < 0xf);
    return new Arm_v4bx_stub(this->stub_templates_[arm_stub_v4_veneer_bx],
			     reg);
  }

 private:
  // Constructor and destructor are protected since we only return a single
  // instance created in Stub_factory::get_instance().

  Stub_factory();

  // A Stub_factory may not be copied since it is a singleton.
  Stub_factory(const Stub_factory&);
  Stub_factory& operator=(Stub_factory&);

  // Stub templates.  These are initialized in the constructor.
  const Stub_template* stub_templates_[arm_stub_type_last+1];
};

// A class to hold stubs for the ARM target.

template<bool big_endian>
class Stub_table : public Output_data
{
 public:
  Stub_table(Arm_input_section<big_endian>* owner)
    : Output_data(), owner_(owner), reloc_stubs_(), reloc_stubs_size_(0),
      reloc_stubs_addralign_(1), cortex_a8_stubs_(), arm_v4bx_stubs_(0xf),
      prev_data_size_(0), prev_addralign_(1)
  { }

  ~Stub_table()
  { }

  // Owner of this stub table.
  Arm_input_section<big_endian>*
  owner() const
  { return this->owner_; }

  // Whether this stub table is empty.
  bool
  empty() const
  {
    return (this->reloc_stubs_.empty()
	    && this->cortex_a8_stubs_.empty()
	    && this->arm_v4bx_stubs_.empty());
  }

  // Return the current data size.
  off_t
  current_data_size() const
  { return this->current_data_size_for_child(); }

  // Add a STUB using KEY.  The caller is responsible for avoiding addition
  // if a STUB with the same key has already been added.
  void
  add_reloc_stub(Reloc_stub* stub, const Reloc_stub::Key& key)
  {
    const Stub_template* stub_template = stub->stub_template();
    gold_assert(stub_template->type() == key.stub_type());
    this->reloc_stubs_[key] = stub;

    // Assign stub offset early.  We can do this because we never remove
    // reloc stubs and they are in the beginning of the stub table.
    uint64_t align = stub_template->alignment();
    this->reloc_stubs_size_ = align_address(this->reloc_stubs_size_, align);
    stub->set_offset(this->reloc_stubs_size_);
    this->reloc_stubs_size_ += stub_template->size();
    this->reloc_stubs_addralign_ =
      std::max(this->reloc_stubs_addralign_, align);
  }

  // Add a Cortex-A8 STUB that fixes up a THUMB branch at ADDRESS.
  // The caller is responsible for avoiding addition if a STUB with the same
  // address has already been added.
  void
  add_cortex_a8_stub(Arm_address address, Cortex_a8_stub* stub)
  {
    std::pair<Arm_address, Cortex_a8_stub*> value(address, stub);
    this->cortex_a8_stubs_.insert(value);
  }

  // Add an ARM V4BX relocation stub. A register index will be retrieved
  // from the stub.
  void
  add_arm_v4bx_stub(Arm_v4bx_stub* stub)
  {
    gold_assert(stub != NULL && this->arm_v4bx_stubs_[stub->reg()] == NULL);
    this->arm_v4bx_stubs_[stub->reg()] = stub;
  }

  // Remove all Cortex-A8 stubs.
  void
  remove_all_cortex_a8_stubs();

  // Look up a relocation stub using KEY.  Return NULL if there is none.
  Reloc_stub*
  find_reloc_stub(const Reloc_stub::Key& key) const
  {
    typename Reloc_stub_map::const_iterator p = this->reloc_stubs_.find(key);
    return (p != this->reloc_stubs_.end()) ? p->second : NULL;
  }

  // Look up an arm v4bx relocation stub using the register index.
  // Return NULL if there is none.
  Arm_v4bx_stub*
  find_arm_v4bx_stub(const uint32_t reg) const
  {
    gold_assert(reg < 0xf);
    return this->arm_v4bx_stubs_[reg];
  }

  // Relocate stubs in this stub table.
  void
  relocate_stubs(const Relocate_info<32, big_endian>*,
		 Target_arm<big_endian>*, Output_section*,
		 unsigned char*, Arm_address, section_size_type);

  // Update data size and alignment at the end of a relaxation pass.  Return
  // true if either data size or alignment is different from that of the
  // previous relaxation pass.
  bool
  update_data_size_and_addralign();

  // Finalize stubs.  Set the offsets of all stubs and mark input sections
  // needing the Cortex-A8 workaround.
  void
  finalize_stubs();

  // Apply Cortex-A8 workaround to an address range.
  void
  apply_cortex_a8_workaround_to_address_range(Target_arm<big_endian>*,
					      unsigned char*, Arm_address,
					      section_size_type);

 protected:
  // Write out section contents.
  void
  do_write(Output_file*);

  // Return the required alignment.
  uint64_t
  do_addralign() const
  { return this->prev_addralign_; }

  // Reset address and file offset.
  void
  do_reset_address_and_file_offset()
  { this->set_current_data_size_for_child(this->prev_data_size_); }

  // Set final data size.
  void
  set_final_data_size()
  { this->set_data_size(this->current_data_size()); }

 private:
  // Relocate one stub.
  void
  relocate_stub(Stub*, const Relocate_info<32, big_endian>*,
		Target_arm<big_endian>*, Output_section*,
		unsigned char*, Arm_address, section_size_type);

  // Unordered map of relocation stubs.
  typedef
    Unordered_map<Reloc_stub::Key, Reloc_stub*, Reloc_stub::Key::hash,
		  Reloc_stub::Key::equal_to>
    Reloc_stub_map;

  // List of Cortex-A8 stubs ordered by addresses of branches being
  // fixed up in output.
  typedef std::map<Arm_address, Cortex_a8_stub*> Cortex_a8_stub_list;
  // List of Arm V4BX relocation stubs ordered by associated registers.
  typedef std::vector<Arm_v4bx_stub*> Arm_v4bx_stub_list;

  // Owner of this stub table.
  Arm_input_section<big_endian>* owner_;
  // The relocation stubs.
  Reloc_stub_map reloc_stubs_;
  // Size of reloc stubs.
  off_t reloc_stubs_size_;
  // Maximum address alignment of reloc stubs.
  uint64_t reloc_stubs_addralign_;
  // The cortex_a8_stubs.
  Cortex_a8_stub_list cortex_a8_stubs_;
  // The Arm V4BX relocation stubs.
  Arm_v4bx_stub_list arm_v4bx_stubs_;
  // data size of this in the previous pass.
  off_t prev_data_size_;
  // address alignment of this in the previous pass.
  uint64_t prev_addralign_;
};

// Arm_exidx_cantunwind class.  This represents an EXIDX_CANTUNWIND entry
// we add to the end of an EXIDX input section that goes into the output.

class Arm_exidx_cantunwind : public Output_section_data
{
 public:
  Arm_exidx_cantunwind(Relobj* relobj, unsigned int shndx)
    : Output_section_data(8, 4, true), relobj_(relobj), shndx_(shndx)
  { }

  // Return the object containing the section pointed by this.
  Relobj*
  relobj() const
  { return this->relobj_; }

  // Return the section index of the section pointed by this.
  unsigned int
  shndx() const
  { return this->shndx_; }

 protected:
  void
  do_write(Output_file* of)
  {
    if (parameters->target().is_big_endian())
      this->do_fixed_endian_write<true>(of);
    else
      this->do_fixed_endian_write<false>(of);
  }

  // Write to a map file.
  void
  do_print_to_mapfile(Mapfile* mapfile) const
  { mapfile->print_output_data(this, _("** ARM cantunwind")); }

 private:
  // Implement do_write for a given endianness.
  template<bool big_endian>
  void inline
  do_fixed_endian_write(Output_file*);

  // The object containing the section pointed by this.
  Relobj* relobj_;
  // The section index of the section pointed by this.
  unsigned int shndx_;
};

// During EXIDX coverage fix-up, we compact an EXIDX section.  The
// Offset map is used to map input section offset within the EXIDX section
// to the output offset from the start of this EXIDX section.

typedef std::map<section_offset_type, section_offset_type>
	Arm_exidx_section_offset_map;

// Arm_exidx_merged_section class.  This represents an EXIDX input section
// with some of its entries merged.

class Arm_exidx_merged_section : public Output_relaxed_input_section
{
 public:
  // Constructor for Arm_exidx_merged_section.
  // EXIDX_INPUT_SECTION points to the unmodified EXIDX input section.
  // SECTION_OFFSET_MAP points to a section offset map describing how
  // parts of the input section are mapped to output.  DELETED_BYTES is
  // the number of bytes deleted from the EXIDX input section.
  Arm_exidx_merged_section(
      const Arm_exidx_input_section& exidx_input_section,
      const Arm_exidx_section_offset_map& section_offset_map,
      uint32_t deleted_bytes);

  // Build output contents.
  void
  build_contents(const unsigned char*, section_size_type);

  // Return the original EXIDX input section.
  const Arm_exidx_input_section&
  exidx_input_section() const
  { return this->exidx_input_section_; }

  // Return the section offset map.
  const Arm_exidx_section_offset_map&
  section_offset_map() const
  { return this->section_offset_map_; }

 protected:
  // Write merged section into file OF.
  void
  do_write(Output_file* of);

  bool
  do_output_offset(const Relobj*, unsigned int, section_offset_type,
		  section_offset_type*) const;

 private:
  // Original EXIDX input section.
  const Arm_exidx_input_section& exidx_input_section_;
  // Section offset map.
  const Arm_exidx_section_offset_map& section_offset_map_;
  // Merged section contents.  We need to keep build the merged section
  // and save it here to avoid accessing the original EXIDX section when
  // we cannot lock the sections' object.
  unsigned char* section_contents_;
};

// A class to wrap an ordinary input section containing executable code.

template<bool big_endian>
class Arm_input_section : public Output_relaxed_input_section
{
 public:
  Arm_input_section(Relobj* relobj, unsigned int shndx)
    : Output_relaxed_input_section(relobj, shndx, 1),
      original_addralign_(1), original_size_(0), stub_table_(NULL),
      original_contents_(NULL)
  { }

  ~Arm_input_section()
  { delete[] this->original_contents_; }

  // Initialize.
  void
  init();

  // Whether this is a stub table owner.
  bool
  is_stub_table_owner() const
  { return this->stub_table_ != NULL && this->stub_table_->owner() == this; }

  // Return the stub table.
  Stub_table<big_endian>*
  stub_table() const
  { return this->stub_table_; }

  // Set the stub_table.
  void
  set_stub_table(Stub_table<big_endian>* stub_table)
  { this->stub_table_ = stub_table; }

  // Downcast a base pointer to an Arm_input_section pointer.  This is
  // not type-safe but we only use Arm_input_section not the base class.
  static Arm_input_section<big_endian>*
  as_arm_input_section(Output_relaxed_input_section* poris)
  { return static_cast<Arm_input_section<big_endian>*>(poris); }

  // Return the original size of the section.
  uint32_t
  original_size() const
  { return this->original_size_; }

 protected:
  // Write data to output file.
  void
  do_write(Output_file*);

  // Return required alignment of this.
  uint64_t
  do_addralign() const
  {
    if (this->is_stub_table_owner())
      return std::max(this->stub_table_->addralign(),
		      static_cast<uint64_t>(this->original_addralign_));
    else
      return this->original_addralign_;
  }

  // Finalize data size.
  void
  set_final_data_size();

  // Reset address and file offset.
  void
  do_reset_address_and_file_offset();

  // Output offset.
  bool
  do_output_offset(const Relobj* object, unsigned int shndx,
		   section_offset_type offset,
		   section_offset_type* poutput) const
  {
    if ((object == this->relobj())
	&& (shndx == this->shndx())
	&& (offset >= 0)
	&& (offset <=
	    convert_types<section_offset_type, uint32_t>(this->original_size_)))
      {
	*poutput = offset;
	return true;
      }
    else
      return false;
  }

 private:
  // Copying is not allowed.
  Arm_input_section(const Arm_input_section&);
  Arm_input_section& operator=(const Arm_input_section&);

  // Address alignment of the original input section.
  uint32_t original_addralign_;
  // Section size of the original input section.
  uint32_t original_size_;
  // Stub table.
  Stub_table<big_endian>* stub_table_;
  // Original section contents.  We have to make a copy here since the file
  // containing the original section may not be locked when we need to access
  // the contents.
  unsigned char* original_contents_;
};

// Arm_exidx_fixup class.  This is used to define a number of methods
// and keep states for fixing up EXIDX coverage.

class Arm_exidx_fixup
{
 public:
  Arm_exidx_fixup(Output_section* exidx_output_section,
		  bool merge_exidx_entries = true)
    : exidx_output_section_(exidx_output_section), last_unwind_type_(UT_NONE),
      last_inlined_entry_(0), last_input_section_(NULL),
      section_offset_map_(NULL), first_output_text_section_(NULL),
      merge_exidx_entries_(merge_exidx_entries)
  { }

  ~Arm_exidx_fixup()
  { delete this->section_offset_map_; }

  // Process an EXIDX section for entry merging.  SECTION_CONTENTS points
  // to the EXIDX contents and SECTION_SIZE is the size of the contents. Return
  // number of bytes to be deleted in output.  If parts of the input EXIDX
  // section are merged a heap allocated Arm_exidx_section_offset_map is store
  // in the located PSECTION_OFFSET_MAP.   The caller owns the map and is
  // responsible for releasing it.
  template<bool big_endian>
  uint32_t
  process_exidx_section(const Arm_exidx_input_section* exidx_input_section,
			const unsigned char* section_contents,
			section_size_type section_size,
			Arm_exidx_section_offset_map** psection_offset_map);

  // Append an EXIDX_CANTUNWIND entry pointing at the end of the last
  // input section, if there is not one already.
  void
  add_exidx_cantunwind_as_needed();

  // Return the output section for the text section which is linked to the
  // first exidx input in output.
  Output_section*
  first_output_text_section() const
  { return this->first_output_text_section_; }

 private:
  // Copying is not allowed.
  Arm_exidx_fixup(const Arm_exidx_fixup&);
  Arm_exidx_fixup& operator=(const Arm_exidx_fixup&);

  // Type of EXIDX unwind entry.
  enum Unwind_type
  {
    // No type.
    UT_NONE,
    // EXIDX_CANTUNWIND.
    UT_EXIDX_CANTUNWIND,
    // Inlined entry.
    UT_INLINED_ENTRY,
    // Normal entry.
    UT_NORMAL_ENTRY,
  };

  // Process an EXIDX entry.  We only care about the second word of the
  // entry.  Return true if the entry can be deleted.
  bool
  process_exidx_entry(uint32_t second_word);

  // Update the current section offset map during EXIDX section fix-up.
  // If there is no map, create one.  INPUT_OFFSET is the offset of a
  // reference point, DELETED_BYTES is the number of deleted by in the
  // section so far.  If DELETE_ENTRY is true, the reference point and
  // all offsets after the previous reference point are discarded.
  void
  update_offset_map(section_offset_type input_offset,
		    section_size_type deleted_bytes, bool delete_entry);

  // EXIDX output section.
  Output_section* exidx_output_section_;
  // Unwind type of the last EXIDX entry processed.
  Unwind_type last_unwind_type_;
  // Last seen inlined EXIDX entry.
  uint32_t last_inlined_entry_;
  // Last processed EXIDX input section.
  const Arm_exidx_input_section* last_input_section_;
  // Section offset map created in process_exidx_section.
  Arm_exidx_section_offset_map* section_offset_map_;
  // Output section for the text section which is linked to the first exidx
  // input in output.
  Output_section* first_output_text_section_;

  bool merge_exidx_entries_;
};

// Arm output section class.  This is defined mainly to add a number of
// stub generation methods.

template<bool big_endian>
class Arm_output_section : public Output_section
{
 public:
  typedef std::vector<std::pair<Relobj*, unsigned int> > Text_section_list;

  // We need to force SHF_LINK_ORDER in a SHT_ARM_EXIDX section.
  Arm_output_section(const char* name, elfcpp::Elf_Word type,
		     elfcpp::Elf_Xword flags)
    : Output_section(name, type,
		     (type == elfcpp::SHT_ARM_EXIDX
		      ? flags | elfcpp::SHF_LINK_ORDER
		      : flags))
  {
    if (type == elfcpp::SHT_ARM_EXIDX)
      this->set_always_keeps_input_sections();
  }

  ~Arm_output_section()
  { }

  // Group input sections for stub generation.
  void
  group_sections(section_size_type, bool, Target_arm<big_endian>*, const Task*);

  // Downcast a base pointer to an Arm_output_section pointer.  This is
  // not type-safe but we only use Arm_output_section not the base class.
  static Arm_output_section<big_endian>*
  as_arm_output_section(Output_section* os)
  { return static_cast<Arm_output_section<big_endian>*>(os); }

  // Append all input text sections in this into LIST.
  void
  append_text_sections_to_list(Text_section_list* list);

  // Fix EXIDX coverage of this EXIDX output section.  SORTED_TEXT_SECTION
  // is a list of text input sections sorted in ascending order of their
  // output addresses.
  void
  fix_exidx_coverage(Layout* layout,
		     const Text_section_list& sorted_text_section,
		     Symbol_table* symtab,
		     bool merge_exidx_entries,
		     const Task* task);

  // Link an EXIDX section into its corresponding text section.
  void
  set_exidx_section_link();

 private:
  // For convenience.
  typedef Output_section::Input_section Input_section;
  typedef Output_section::Input_section_list Input_section_list;

  // Create a stub group.
  void create_stub_group(Input_section_list::const_iterator,
			 Input_section_list::const_iterator,
			 Input_section_list::const_iterator,
			 Target_arm<big_endian>*,
			 std::vector<Output_relaxed_input_section*>*,
			 const Task* task);
};

// Arm_exidx_input_section class.  This represents an EXIDX input section.

class Arm_exidx_input_section
{
 public:
  static const section_offset_type invalid_offset =
    static_cast<section_offset_type>(-1);

  Arm_exidx_input_section(Relobj* relobj, unsigned int shndx,
			  unsigned int link, uint32_t size,
			  uint32_t addralign, uint32_t text_size)
    : relobj_(relobj), shndx_(shndx), link_(link), size_(size),
      addralign_(addralign), text_size_(text_size), has_errors_(false)
  { }

  ~Arm_exidx_input_section()
  { }

  // Accessors:  This is a read-only class.

  // Return the object containing this EXIDX input section.
  Relobj*
  relobj() const
  { return this->relobj_; }

  // Return the section index of this EXIDX input section.
  unsigned int
  shndx() const
  { return this->shndx_; }

  // Return the section index of linked text section in the same object.
  unsigned int
  link() const
  { return this->link_; }

  // Return size of the EXIDX input section.
  uint32_t
  size() const
  { return this->size_; }

  // Return address alignment of EXIDX input section.
  uint32_t
  addralign() const
  { return this->addralign_; }

  // Return size of the associated text input section.
  uint32_t
  text_size() const
  { return this->text_size_; }

  // Whether there are any errors in the EXIDX input section.
  bool
  has_errors() const
  { return this->has_errors_; }

  // Set has-errors flag.
  void
  set_has_errors()
  { this->has_errors_ = true; }

 private:
  // Object containing this.
  Relobj* relobj_;
  // Section index of this.
  unsigned int shndx_;
  // text section linked to this in the same object.
  unsigned int link_;
  // Size of this.  For ARM 32-bit is sufficient.
  uint32_t size_;
  // Address alignment of this.  For ARM 32-bit is sufficient.
  uint32_t addralign_;
  // Size of associated text section.
  uint32_t text_size_;
  // Whether this has any errors.
  bool has_errors_;
};

// Arm_relobj class.

template<bool big_endian>
class Arm_relobj : public Sized_relobj_file<32, big_endian>
{
 public:
  static const Arm_address invalid_address = static_cast<Arm_address>(-1);

  Arm_relobj(const std::string& name, Input_file* input_file, off_t offset,
	     const typename elfcpp::Ehdr<32, big_endian>& ehdr)
    : Sized_relobj_file<32, big_endian>(name, input_file, offset, ehdr),
      stub_tables_(), local_symbol_is_thumb_function_(),
      attributes_section_data_(NULL), mapping_symbols_info_(),
      section_has_cortex_a8_workaround_(NULL), exidx_section_map_(),
      output_local_symbol_count_needs_update_(false),
      merge_flags_and_attributes_(true)
  { }

  ~Arm_relobj()
  { delete this->attributes_section_data_; }

  // Return the stub table of the SHNDX-th section if there is one.
  Stub_table<big_endian>*
  stub_table(unsigned int shndx) const
  {
    gold_assert(shndx < this->stub_tables_.size());
    return this->stub_tables_[shndx];
  }

  // Set STUB_TABLE to be the stub_table of the SHNDX-th section.
  void
  set_stub_table(unsigned int shndx, Stub_table<big_endian>* stub_table)
  {
    gold_assert(shndx < this->stub_tables_.size());
    this->stub_tables_[shndx] = stub_table;
  }

  // Whether a local symbol is a THUMB function.  R_SYM is the symbol table
  // index.  This is only valid after do_count_local_symbol is called.
  bool
  local_symbol_is_thumb_function(unsigned int r_sym) const
  {
    gold_assert(r_sym < this->local_symbol_is_thumb_function_.size());
    return this->local_symbol_is_thumb_function_[r_sym];
  }

  // Scan all relocation sections for stub generation.
  void
  scan_sections_for_stubs(Target_arm<big_endian>*, const Symbol_table*,
			  const Layout*);

  // Convert regular input section with index SHNDX to a relaxed section.
  void
  convert_input_section_to_relaxed_section(unsigned shndx)
  {
    // The stubs have relocations and we need to process them after writing
    // out the stubs.  So relocation now must follow section write.
    this->set_section_offset(shndx, -1ULL);
    this->set_relocs_must_follow_section_writes();
  }

  // Downcast a base pointer to an Arm_relobj pointer.  This is
  // not type-safe but we only use Arm_relobj not the base class.
  static Arm_relobj<big_endian>*
  as_arm_relobj(Relobj* relobj)
  { return static_cast<Arm_relobj<big_endian>*>(relobj); }

  // Processor-specific flags in ELF file header.  This is valid only after
  // reading symbols.
  elfcpp::Elf_Word
  processor_specific_flags() const
  { return this->processor_specific_flags_; }

  // Attribute section data  This is the contents of the .ARM.attribute section
  // if there is one.
  const Attributes_section_data*
  attributes_section_data() const
  { return this->attributes_section_data_; }

  // Mapping symbol location.
  typedef std::pair<unsigned int, Arm_address> Mapping_symbol_position;

  // Functor for STL container.
  struct Mapping_symbol_position_less
  {
    bool
    operator()(const Mapping_symbol_position& p1,
	       const Mapping_symbol_position& p2) const
    {
      return (p1.first < p2.first
	      || (p1.first == p2.first && p1.second < p2.second));
    }
  };

  // We only care about the first character of a mapping symbol, so
  // we only store that instead of the whole symbol name.
  typedef std::map<Mapping_symbol_position, char,
		   Mapping_symbol_position_less> Mapping_symbols_info;

  // Whether a section contains any Cortex-A8 workaround.
  bool
  section_has_cortex_a8_workaround(unsigned int shndx) const
  {
    return (this->section_has_cortex_a8_workaround_ != NULL
	    && (*this->section_has_cortex_a8_workaround_)[shndx]);
  }

  // Mark a section that has Cortex-A8 workaround.
  void
  mark_section_for_cortex_a8_workaround(unsigned int shndx)
  {
    if (this->section_has_cortex_a8_workaround_ == NULL)
      this->section_has_cortex_a8_workaround_ =
	new std::vector<bool>(this->shnum(), false);
    (*this->section_has_cortex_a8_workaround_)[shndx] = true;
  }

  // Return the EXIDX section of an text section with index SHNDX or NULL
  // if the text section has no associated EXIDX section.
  const Arm_exidx_input_section*
  exidx_input_section_by_link(unsigned int shndx) const
  {
    Exidx_section_map::const_iterator p = this->exidx_section_map_.find(shndx);
    return ((p != this->exidx_section_map_.end()
	     && p->second->link() == shndx)
	    ? p->second
	    : NULL);
  }

  // Return the EXIDX section with index SHNDX or NULL if there is none.
  const Arm_exidx_input_section*
  exidx_input_section_by_shndx(unsigned shndx) const
  {
    Exidx_section_map::const_iterator p = this->exidx_section_map_.find(shndx);
    return ((p != this->exidx_section_map_.end()
	     && p->second->shndx() == shndx)
	    ? p->second
	    : NULL);
  }

  // Whether output local symbol count needs updating.
  bool
  output_local_symbol_count_needs_update() const
  { return this->output_local_symbol_count_needs_update_; }

  // Set output_local_symbol_count_needs_update flag to be true.
  void
  set_output_local_symbol_count_needs_update()
  { this->output_local_symbol_count_needs_update_ = true; }

  // Update output local symbol count at the end of relaxation.
  void
  update_output_local_symbol_count();

  // Whether we want to merge processor-specific flags and attributes.
  bool
  merge_flags_and_attributes() const
  { return this->merge_flags_and_attributes_; }

  // Export list of EXIDX section indices.
  void
  get_exidx_shndx_list(std::vector<unsigned int>* list) const
  {
    list->clear();
    for (Exidx_section_map::const_iterator p = this->exidx_section_map_.begin();
	 p != this->exidx_section_map_.end();
	 ++p)
      {
	if (p->second->shndx() == p->first)
	  list->push_back(p->first);
      }
    // Sort list to make result independent of implementation of map.
    std::sort(list->begin(), list->end());
  }

 protected:
  // Post constructor setup.
  void
  do_setup()
  {
    // Call parent's setup method.
    Sized_relobj_file<32, big_endian>::do_setup();

    // Initialize look-up tables.
    Stub_table_list empty_stub_table_list(this->shnum(), NULL);
    this->stub_tables_.swap(empty_stub_table_list);
  }

  // Count the local symbols.
  void
  do_count_local_symbols(Stringpool_template<char>*,
			 Stringpool_template<char>*);

  void
  do_relocate_sections(
      const Symbol_table* symtab, const Layout* layout,
      const unsigned char* pshdrs, Output_file* of,
      typename Sized_relobj_file<32, big_endian>::Views* pivews);

  // Read the symbol information.
  void
  do_read_symbols(Read_symbols_data* sd);

  // Process relocs for garbage collection.
  void
  do_gc_process_relocs(Symbol_table*, Layout*, Read_relocs_data*);

 private:

  // Whether a section needs to be scanned for relocation stubs.
  bool
  section_needs_reloc_stub_scanning(const elfcpp::Shdr<32, big_endian>&,
				    const Relobj::Output_sections&,
				    const Symbol_table*, const unsigned char*);

  // Whether a section is a scannable text section.
  bool
  section_is_scannable(const elfcpp::Shdr<32, big_endian>&, unsigned int,
		       const Output_section*, const Symbol_table*);

  // Whether a section needs to be scanned for the Cortex-A8 erratum.
  bool
  section_needs_cortex_a8_stub_scanning(const elfcpp::Shdr<32, big_endian>&,
					unsigned int, Output_section*,
					const Symbol_table*);

  // Scan a section for the Cortex-A8 erratum.
  void
  scan_section_for_cortex_a8_erratum(const elfcpp::Shdr<32, big_endian>&,
				     unsigned int, Output_section*,
				     Target_arm<big_endian>*);

  // Find the linked text section of an EXIDX section by looking at the
  // first relocation of the EXIDX section.  PSHDR points to the section
  // headers of a relocation section and PSYMS points to the local symbols.
  // PSHNDX points to a location storing the text section index if found.
  // Return whether we can find the linked section.
  bool
  find_linked_text_section(const unsigned char* pshdr,
			   const unsigned char* psyms, unsigned int* pshndx);

  //
  // Make a new Arm_exidx_input_section object for EXIDX section with
  // index SHNDX and section header SHDR.  TEXT_SHNDX is the section
  // index of the linked text section.
  void
  make_exidx_input_section(unsigned int shndx,
			   const elfcpp::Shdr<32, big_endian>& shdr,
			   unsigned int text_shndx,
			   const elfcpp::Shdr<32, big_endian>& text_shdr);

  // Return the output address of either a plain input section or a
  // relaxed input section.  SHNDX is the section index.
  Arm_address
  simple_input_section_output_address(unsigned int, Output_section*);

  typedef std::vector<Stub_table<big_endian>*> Stub_table_list;
  typedef Unordered_map<unsigned int, const Arm_exidx_input_section*>
    Exidx_section_map;

  // List of stub tables.
  Stub_table_list stub_tables_;
  // Bit vector to tell if a local symbol is a thumb function or not.
  // This is only valid after do_count_local_symbol is called.
  std::vector<bool> local_symbol_is_thumb_function_;
  // processor-specific flags in ELF file header.
  elfcpp::Elf_Word processor_specific_flags_;
  // Object attributes if there is an .ARM.attributes section or NULL.
  Attributes_section_data* attributes_section_data_;
  // Mapping symbols information.
  Mapping_symbols_info mapping_symbols_info_;
  // Bitmap to indicate sections with Cortex-A8 workaround or NULL.
  std::vector<bool>* section_has_cortex_a8_workaround_;
  // Map a text section to its associated .ARM.exidx section, if there is one.
  Exidx_section_map exidx_section_map_;
  // Whether output local symbol count needs updating.
  bool output_local_symbol_count_needs_update_;
  // Whether we merge processor flags and attributes of this object to
  // output.
  bool merge_flags_and_attributes_;
};

// Arm_dynobj class.

template<bool big_endian>
class Arm_dynobj : public Sized_dynobj<32, big_endian>
{
 public:
  Arm_dynobj(const std::string& name, Input_file* input_file, off_t offset,
	     const elfcpp::Ehdr<32, big_endian>& ehdr)
    : Sized_dynobj<32, big_endian>(name, input_file, offset, ehdr),
      processor_specific_flags_(0), attributes_section_data_(NULL)
  { }

  ~Arm_dynobj()
  { delete this->attributes_section_data_; }

  // Downcast a base pointer to an Arm_relobj pointer.  This is
  // not type-safe but we only use Arm_relobj not the base class.
  static Arm_dynobj<big_endian>*
  as_arm_dynobj(Dynobj* dynobj)
  { return static_cast<Arm_dynobj<big_endian>*>(dynobj); }

  // Processor-specific flags in ELF file header.  This is valid only after
  // reading symbols.
  elfcpp::Elf_Word
  processor_specific_flags() const
  { return this->processor_specific_flags_; }

  // Attributes section data.
  const Attributes_section_data*
  attributes_section_data() const
  { return this->attributes_section_data_; }

 protected:
  // Read the symbol information.
  void
  do_read_symbols(Read_symbols_data* sd);

 private:
  // processor-specific flags in ELF file header.
  elfcpp::Elf_Word processor_specific_flags_;
  // Object attributes if there is an .ARM.attributes section or NULL.
  Attributes_section_data* attributes_section_data_;
};

// Functor to read reloc addends during stub generation.

template<int sh_type, bool big_endian>
struct Stub_addend_reader
{
  // Return the addend for a relocation of a particular type.  Depending
  // on whether this is a REL or RELA relocation, read the addend from a
  // view or from a Reloc object.
  elfcpp::Elf_types<32>::Elf_Swxword
  operator()(
    unsigned int /* r_type */,
    const unsigned char* /* view */,
    const typename Reloc_types<sh_type,
			       32, big_endian>::Reloc& /* reloc */) const;
};

// Specialized Stub_addend_reader for SHT_REL type relocation sections.

template<bool big_endian>
struct Stub_addend_reader<elfcpp::SHT_REL, big_endian>
{
  elfcpp::Elf_types<32>::Elf_Swxword
  operator()(
    unsigned int,
    const unsigned char*,
    const typename Reloc_types<elfcpp::SHT_REL, 32, big_endian>::Reloc&) const;
};

// Specialized Stub_addend_reader for RELA type relocation sections.
// We currently do not handle RELA type relocation sections but it is trivial
// to implement the addend reader.  This is provided for completeness and to
// make it easier to add support for RELA relocation sections in the future.

template<bool big_endian>
struct Stub_addend_reader<elfcpp::SHT_RELA, big_endian>
{
  elfcpp::Elf_types<32>::Elf_Swxword
  operator()(
    unsigned int,
    const unsigned char*,
    const typename Reloc_types<elfcpp::SHT_RELA, 32,
			       big_endian>::Reloc& reloc) const
  { return reloc.get_r_addend(); }
};

// Cortex_a8_reloc class.  We keep record of relocation that may need
// the Cortex-A8 erratum workaround.

class Cortex_a8_reloc
{
 public:
  Cortex_a8_reloc(Reloc_stub* reloc_stub, unsigned r_type,
		  Arm_address destination)
    : reloc_stub_(reloc_stub), r_type_(r_type), destination_(destination)
  { }

  ~Cortex_a8_reloc()
  { }

  // Accessors:  This is a read-only class.

  // Return the relocation stub associated with this relocation if there is
  // one.
  const Reloc_stub*
  reloc_stub() const
  { return this->reloc_stub_; }

  // Return the relocation type.
  unsigned int
  r_type() const
  { return this->r_type_; }

  // Return the destination address of the relocation.  LSB stores the THUMB
  // bit.
  Arm_address
  destination() const
  { return this->destination_; }

 private:
  // Associated relocation stub if there is one, or NULL.
  const Reloc_stub* reloc_stub_;
  // Relocation type.
  unsigned int r_type_;
  // Destination address of this relocation.  LSB is used to distinguish
  // ARM/THUMB mode.
  Arm_address destination_;
};

// Arm_output_data_got class.  We derive this from Output_data_got to add
// extra methods to handle TLS relocations in a static link.

template<bool big_endian>
class Arm_output_data_got : public Output_data_got<32, big_endian>
{
 public:
  Arm_output_data_got(Symbol_table* symtab, Layout* layout)
    : Output_data_got<32, big_endian>(), symbol_table_(symtab), layout_(layout)
  { }

  // Add a static entry for the GOT entry at OFFSET.  GSYM is a global
  // symbol and R_TYPE is the code of a dynamic relocation that needs to be
  // applied in a static link.
  void
  add_static_reloc(unsigned int got_offset, unsigned int r_type, Symbol* gsym)
  { this->static_relocs_.push_back(Static_reloc(got_offset, r_type, gsym)); }

  // Add a static reloc for the GOT entry at OFFSET.  RELOBJ is an object
  // defining a local symbol with INDEX.  R_TYPE is the code of a dynamic
  // relocation that needs to be applied in a static link.
  void
  add_static_reloc(unsigned int got_offset, unsigned int r_type,
		   Sized_relobj_file<32, big_endian>* relobj,
		   unsigned int index)
  {
    this->static_relocs_.push_back(Static_reloc(got_offset, r_type, relobj,
						index));
  }

  // Add a GOT pair for R_ARM_TLS_GD32.  The creates a pair of GOT entries.
  // The first one is initialized to be 1, which is the module index for
  // the main executable and the second one 0.  A reloc of the type
  // R_ARM_TLS_DTPOFF32 will be created for the second GOT entry and will
  // be applied by gold.  GSYM is a global symbol.
  void
  add_tls_gd32_with_static_reloc(unsigned int got_type, Symbol* gsym);

  // Same as the above but for a local symbol in OBJECT with INDEX.
  void
  add_tls_gd32_with_static_reloc(unsigned int got_type,
				 Sized_relobj_file<32, big_endian>* object,
				 unsigned int index);

 protected:
  // Write out the GOT table.
  void
  do_write(Output_file*);

 private:
  // This class represent dynamic relocations that need to be applied by
  // gold because we are using TLS relocations in a static link.
  class Static_reloc
  {
   public:
    Static_reloc(unsigned int got_offset, unsigned int r_type, Symbol* gsym)
      : got_offset_(got_offset), r_type_(r_type), symbol_is_global_(true)
    { this->u_.global.symbol = gsym; }

    Static_reloc(unsigned int got_offset, unsigned int r_type,
	  Sized_relobj_file<32, big_endian>* relobj, unsigned int index)
      : got_offset_(got_offset), r_type_(r_type), symbol_is_global_(false)
    {
      this->u_.local.relobj = relobj;
      this->u_.local.index = index;
    }

    // Return the GOT offset.
    unsigned int
    got_offset() const
    { return this->got_offset_; }

    // Relocation type.
    unsigned int
    r_type() const
    { return this->r_type_; }

    // Whether the symbol is global or not.
    bool
    symbol_is_global() const
    { return this->symbol_is_global_; }

    // For a relocation against a global symbol, the global symbol.
    Symbol*
    symbol() const
    {
      gold_assert(this->symbol_is_global_);
      return this->u_.global.symbol;
    }

    // For a relocation against a local symbol, the defining object.
    Sized_relobj_file<32, big_endian>*
    relobj() const
    {
      gold_assert(!this->symbol_is_global_);
      return this->u_.local.relobj;
    }

    // For a relocation against a local symbol, the local symbol index.
    unsigned int
    index() const
    {
      gold_assert(!this->symbol_is_global_);
      return this->u_.local.index;
    }

   private:
    // GOT offset of the entry to which this relocation is applied.
    unsigned int got_offset_;
    // Type of relocation.
    unsigned int r_type_;
    // Whether this relocation is against a global symbol.
    bool symbol_is_global_;
    // A global or local symbol.
    union
    {
      struct
      {
	// For a global symbol, the symbol itself.
	Symbol* symbol;
      } global;
      struct
      {
	// For a local symbol, the object defining object.
	Sized_relobj_file<32, big_endian>* relobj;
	// For a local symbol, the symbol index.
	unsigned int index;
      } local;
    } u_;
  };

  // Symbol table of the output object.
  Symbol_table* symbol_table_;
  // Layout of the output object.
  Layout* layout_;
  // Static relocs to be applied to the GOT.
  std::vector<Static_reloc> static_relocs_;
};

// The ARM target has many relocation types with odd-sizes or noncontiguous
// bits.  The default handling of relocatable relocation cannot process these
// relocations.  So we have to extend the default code.

template<bool big_endian, typename Classify_reloc>
class Arm_scan_relocatable_relocs :
  public Default_scan_relocatable_relocs<Classify_reloc>
{
 public:
  // Return the strategy to use for a local symbol which is a section
  // symbol, given the relocation type.
  inline Relocatable_relocs::Reloc_strategy
  local_section_strategy(unsigned int r_type, Relobj*)
  {
    if (Classify_reloc::sh_type == elfcpp::SHT_RELA)
      return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_RELA;
    else
      {
	if (r_type == elfcpp::R_ARM_TARGET1
	    || r_type == elfcpp::R_ARM_TARGET2)
	  {
	    const Target_arm<big_endian>* arm_target =
	      Target_arm<big_endian>::default_target();
	    r_type = arm_target->get_real_reloc_type(r_type);
	  }

	switch(r_type)
	  {
	  // Relocations that write nothing.  These exclude R_ARM_TARGET1
	  // and R_ARM_TARGET2.
	  case elfcpp::R_ARM_NONE:
	  case elfcpp::R_ARM_V4BX:
	  case elfcpp::R_ARM_TLS_GOTDESC:
	  case elfcpp::R_ARM_TLS_CALL:
	  case elfcpp::R_ARM_TLS_DESCSEQ:
	  case elfcpp::R_ARM_THM_TLS_CALL:
	  case elfcpp::R_ARM_GOTRELAX:
	  case elfcpp::R_ARM_GNU_VTENTRY:
	  case elfcpp::R_ARM_GNU_VTINHERIT:
	  case elfcpp::R_ARM_THM_TLS_DESCSEQ16:
	  case elfcpp::R_ARM_THM_TLS_DESCSEQ32:
	    return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_0;
	  // These should have been converted to something else above.
	  case elfcpp::R_ARM_TARGET1:
	  case elfcpp::R_ARM_TARGET2:
	    gold_unreachable();
	  // Relocations that write full 32 bits and
	  // have alignment of 1.
	  case elfcpp::R_ARM_ABS32:
	  case elfcpp::R_ARM_REL32:
	  case elfcpp::R_ARM_SBREL32:
	  case elfcpp::R_ARM_GOTOFF32:
	  case elfcpp::R_ARM_BASE_PREL:
	  case elfcpp::R_ARM_GOT_BREL:
	  case elfcpp::R_ARM_BASE_ABS:
	  case elfcpp::R_ARM_ABS32_NOI:
	  case elfcpp::R_ARM_REL32_NOI:
	  case elfcpp::R_ARM_PLT32_ABS:
	  case elfcpp::R_ARM_GOT_ABS:
	  case elfcpp::R_ARM_GOT_PREL:
	  case elfcpp::R_ARM_TLS_GD32:
	  case elfcpp::R_ARM_TLS_LDM32:
	  case elfcpp::R_ARM_TLS_LDO32:
	  case elfcpp::R_ARM_TLS_IE32:
	  case elfcpp::R_ARM_TLS_LE32:
	    return Relocatable_relocs::RELOC_ADJUST_FOR_SECTION_4_UNALIGNED;
	  default:
	    // For all other static relocations, return RELOC_SPECIAL.
	    return Relocatable_relocs::RELOC_SPECIAL;
	  }
      }
  }
};

template<bool big_endian>
class Target_arm : public Sized_target<32, big_endian>
{
 public:
  typedef Output_data_reloc<elfcpp::SHT_REL, true, 32, big_endian>
    Reloc_section;

  // When were are relocating a stub, we pass this as the relocation number.
  static const size_t fake_relnum_for_stubs = static_cast<size_t>(-1);

  Target_arm(const Target::Target_info* info = &arm_info)
    : Sized_target<32, big_endian>(info),
      got_(NULL), plt_(NULL), got_plt_(NULL), got_irelative_(NULL),
      rel_dyn_(NULL), rel_irelative_(NULL), copy_relocs_(elfcpp::R_ARM_COPY),
      got_mod_index_offset_(-1U), tls_base_symbol_defined_(false),
      stub_tables_(), stub_factory_(Stub_factory::get_instance()),
      should_force_pic_veneer_(false),
      arm_input_section_map_(), attributes_section_data_(NULL),
      fix_cortex_a8_(false), cortex_a8_relocs_info_(),
      target1_reloc_(elfcpp::R_ARM_ABS32),
      // This can be any reloc type but usually is R_ARM_GOT_PREL.
      target2_reloc_(elfcpp::R_ARM_GOT_PREL)
  { }

  // Whether we force PCI branch veneers.
  bool
  should_force_pic_veneer() const
  { return this->should_force_pic_veneer_; }

  // Set PIC veneer flag.
  void
  set_should_force_pic_veneer(bool value)
  { this->should_force_pic_veneer_ = value; }

  // Whether we use THUMB-2 instructions.
  bool
  using_thumb2() const
  {
    Object_attribute* attr =
      this->get_aeabi_object_attribute(elfcpp::Tag_CPU_arch);
    int arch = attr->int_value();
    return arch == elfcpp::TAG_CPU_ARCH_V6T2 || arch >= elfcpp::TAG_CPU_ARCH_V7;
  }

  // Whether we use THUMB/THUMB-2 instructions only.
  bool
  using_thumb_only() const
  {
    Object_attribute* attr =
      this->get_aeabi_object_attribute(elfcpp::Tag_CPU_arch);

    if (attr->int_value() == elfcpp::TAG_CPU_ARCH_V6_M
	|| attr->int_value() == elfcpp::TAG_CPU_ARCH_V6S_M)
      return true;
    if (attr->int_value() != elfcpp::TAG_CPU_ARCH_V7
	&& attr->int_value() != elfcpp::TAG_CPU_ARCH_V7E_M)
      return false;
    attr = this->get_aeabi_object_attribute(elfcpp::Tag_CPU_arch_profile);
    return attr->int_value() == 'M';
  }

  // Whether we have an NOP instruction.  If not, use mov r0, r0 instead.
  bool
  may_use_arm_nop() const
  {
    Object_attribute* attr =
      this->get_aeabi_object_attribute(elfcpp::Tag_CPU_arch);
    int arch = attr->int_value();
    return (arch == elfcpp::TAG_CPU_ARCH_V6T2
	    || arch == elfcpp::TAG_CPU_ARCH_V6K
	    || arch == elfcpp::TAG_CPU_ARCH_V7
	    || arch == elfcpp::TAG_CPU_ARCH_V7E_M);
  }

  // Whether we have THUMB-2 NOP.W instruction.
  bool
  may_use_thumb2_nop() const
  {
    Object_attribute* attr =
      this->get_aeabi_object_attribute(elfcpp::Tag_CPU_arch);
    int arch = attr->int_value();
    return (arch == elfcpp::TAG_CPU_ARCH_V6T2
	    || arch == elfcpp::TAG_CPU_ARCH_V7
	    || arch == elfcpp::TAG_CPU_ARCH_V7E_M);
  }

  // Whether we have v4T interworking instructions available.
  bool
  may_use_v4t_interworking() const
  {
    Object_attribute* attr =
      this->get_aeabi_object_attribute(elfcpp::Tag_CPU_arch);
    int arch = attr->int_value();
    return (arch != elfcpp::TAG_CPU_ARCH_PRE_V4
	    && arch != elfcpp::TAG_CPU_ARCH_V4);
  }

  // Whether we have v5T interworking instructions available.
  bool
  may_use_v5t_interworking() const
  {
    Object_attribute* attr =
      this->get_aeabi_object_attribute(elfcpp::Tag_CPU_arch);
    int arch = attr->int_value();
    if (parameters->options().fix_arm1176())
      return (arch == elfcpp::TAG_CPU_ARCH_V6T2
	      || arch == elfcpp::TAG_CPU_ARCH_V7
	      || arch == elfcpp::TAG_CPU_ARCH_V6_M
	      || arch == elfcpp::TAG_CPU_ARCH_V6S_M
	      || arch == elfcpp::TAG_CPU_ARCH_V7E_M);
    else
      return (arch != elfcpp::TAG_CPU_ARCH_PRE_V4
	      && arch != elfcpp::TAG_CPU_ARCH_V4
	      && arch != elfcpp::TAG_CPU_ARCH_V4T);
  }

  // Process the relocations to determine unreferenced sections for
  // garbage collection.
  void
  gc_process_relocs(Symbol_table* symtab,
		    Layout* layout,
		    Sized_relobj_file<32, big_endian>* object,
		    unsigned int data_shndx,
		    unsigned int sh_type,
		    const unsigned char* prelocs,
		    size_t reloc_count,
		    Output_section* output_section,
		    bool needs_special_offset_handling,
		    size_t local_symbol_count,
		    const unsigned char* plocal_symbols);

  // Scan the relocations to look for symbol adjustments.
  void
  scan_relocs(Symbol_table* symtab,
	      Layout* layout,
	      Sized_relobj_file<32, big_endian>* object,
	      unsigned int data_shndx,
	      unsigned int sh_type,
	      const unsigned char* prelocs,
	      size_t reloc_count,
	      Output_section* output_section,
	      bool needs_special_offset_handling,
	      size_t local_symbol_count,
	      const unsigned char* plocal_symbols);

  // Finalize the sections.
  void
  do_finalize_sections(Layout*, const Input_objects*, Symbol_table*);

  // Return the value to use for a dynamic symbol which requires special
  // treatment.
  uint64_t
  do_dynsym_value(const Symbol*) const;

  // Return the plt address for globals. Since we have irelative plt entries,
  // address calculation is not as straightforward as plt_address + plt_offset.
  uint64_t
  do_plt_address_for_global(const Symbol* gsym) const
  { return this->plt_section()->address_for_global(gsym); }

  // Return the plt address for locals. Since we have irelative plt entries,
  // address calculation is not as straightforward as plt_address + plt_offset.
  uint64_t
  do_plt_address_for_local(const Relobj* relobj, unsigned int symndx) const
  { return this->plt_section()->address_for_local(relobj, symndx); }

  // Relocate a section.
  void
  relocate_section(const Relocate_info<32, big_endian>*,
		   unsigned int sh_type,
		   const unsigned char* prelocs,
		   size_t reloc_count,
		   Output_section* output_section,
		   bool needs_special_offset_handling,
		   unsigned char* view,
		   Arm_address view_address,
		   section_size_type view_size,
		   const Reloc_symbol_changes*);

  // Scan the relocs during a relocatable link.
  void
  scan_relocatable_relocs(Symbol_table* symtab,
			  Layout* layout,
			  Sized_relobj_file<32, big_endian>* object,
			  unsigned int data_shndx,
			  unsigned int sh_type,
			  const unsigned char* prelocs,
			  size_t reloc_count,
			  Output_section* output_section,
			  bool needs_special_offset_handling,
			  size_t local_symbol_count,
			  const unsigned char* plocal_symbols,
			  Relocatable_relocs*);

  // Scan the relocs for --emit-relocs.
  void
  emit_relocs_scan(Symbol_table* symtab,
		   Layout* layout,
		   Sized_relobj_file<32, big_endian>* object,
		   unsigned int data_shndx,
		   unsigned int sh_type,
		   const unsigned char* prelocs,
		   size_t reloc_count,
		   Output_section* output_section,
		   bool needs_special_offset_handling,
		   size_t local_symbol_count,
		   const unsigned char* plocal_syms,
		   Relocatable_relocs* rr);

  // Emit relocations for a section.
  void
  relocate_relocs(const Relocate_info<32, big_endian>*,
		  unsigned int sh_type,
		  const unsigned char* prelocs,
		  size_t reloc_count,
		  Output_section* output_section,
		  typename elfcpp::Elf_types<32>::Elf_Off
                    offset_in_output_section,
		  unsigned char* view,
		  Arm_address view_address,
		  section_size_type view_size,
		  unsigned char* reloc_view,
		  section_size_type reloc_view_size);

  // Perform target-specific processing in a relocatable link.  This is
  // only used if we use the relocation strategy RELOC_SPECIAL.
  void
  relocate_special_relocatable(const Relocate_info<32, big_endian>* relinfo,
			       unsigned int sh_type,
			       const unsigned char* preloc_in,
			       size_t relnum,
			       Output_section* output_section,
			       typename elfcpp::Elf_types<32>::Elf_Off
                                 offset_in_output_section,
			       unsigned char* view,
			       typename elfcpp::Elf_types<32>::Elf_Addr
				 view_address,
			       section_size_type view_size,
			       unsigned char* preloc_out);

  // Return whether SYM is defined by the ABI.
  bool
  do_is_defined_by_abi(const Symbol* sym) const
  { return strcmp(sym->name(), "__tls_get_addr") == 0; }

  // Return whether there is a GOT section.
  bool
  has_got_section() const
  { return this->got_ != NULL; }

  // Return the size of the GOT section.
  section_size_type
  got_size() const
  {
    gold_assert(this->got_ != NULL);
    return this->got_->data_size();
  }

  // Return the number of entries in the GOT.
  unsigned int
  got_entry_count() const
  {
    if (!this->has_got_section())
      return 0;
    return this->got_size() / 4;
  }

  // Return the number of entries in the PLT.
  unsigned int
  plt_entry_count() const;

  // Return the offset of the first non-reserved PLT entry.
  unsigned int
  first_plt_entry_offset() const;

  // Return the size of each PLT entry.
  unsigned int
  plt_entry_size() const;

  // Get the section to use for IRELATIVE relocations, create it if necessary.
  Reloc_section*
  rel_irelative_section(Layout*);

  // Map platform-specific reloc types
  unsigned int
  get_real_reloc_type(unsigned int r_type) const;

  //
  // Methods to support stub-generations.
  //

  // Return the stub factory
  const Stub_factory&
  stub_factory() const
  { return this->stub_factory_; }

  // Make a new Arm_input_section object.
  Arm_input_section<big_endian>*
  new_arm_input_section(Relobj*, unsigned int);

  // Find the Arm_input_section object corresponding to the SHNDX-th input
  // section of RELOBJ.
  Arm_input_section<big_endian>*
  find_arm_input_section(Relobj* relobj, unsigned int shndx) const;

  // Make a new Stub_table
  Stub_table<big_endian>*
  new_stub_table(Arm_input_section<big_endian>*);

  // Scan a section for stub generation.
  void
  scan_section_for_stubs(const Relocate_info<32, big_endian>*, unsigned int,
			 const unsigned char*, size_t, Output_section*,
			 bool, const unsigned char*, Arm_address,
			 section_size_type);

  // Relocate a stub.
  void
  relocate_stub(Stub*, const Relocate_info<32, big_endian>*,
		Output_section*, unsigned char*, Arm_address,
		section_size_type);

  // Get the default ARM target.
  static Target_arm<big_endian>*
  default_target()
  {
    gold_assert(parameters->target().machine_code() == elfcpp::EM_ARM
		&& parameters->target().is_big_endian() == big_endian);
    return static_cast<Target_arm<big_endian>*>(
	     parameters->sized_target<32, big_endian>());
  }

  // Whether NAME belongs to a mapping symbol.
  static bool
  is_mapping_symbol_name(const char* name)
  {
    return (name
	    && name[0] == '$'
	    && (name[1] == 'a' || name[1] == 't' || name[1] == 'd')
	    && (name[2] == '\0' || name[2] == '.'));
  }

  // Whether we work around the Cortex-A8 erratum.
  bool
  fix_cortex_a8() const
  { return this->fix_cortex_a8_; }

  // Whether we merge exidx entries in debuginfo.
  bool
  merge_exidx_entries() const
  { return parameters->options().merge_exidx_entries(); }

  // Whether we fix R_ARM_V4BX relocation.
  // 0 - do not fix
  // 1 - replace with MOV instruction (armv4 target)
  // 2 - make interworking veneer (>= armv4t targets only)
  General_options::Fix_v4bx
  fix_v4bx() const
  { return parameters->options().fix_v4bx(); }

  // Scan a span of THUMB code section for Cortex-A8 erratum.
  void
  scan_span_for_cortex_a8_erratum(Arm_relobj<big_endian>*, unsigned int,
				  section_size_type, section_size_type,
				  const unsigned char*, Arm_address);

  // Apply Cortex-A8 workaround to a branch.
  void
  apply_cortex_a8_workaround(const Cortex_a8_stub*, Arm_address,
			     unsigned char*, Arm_address);

 protected:
  // Make the PLT-generator object.
  Output_data_plt_arm<big_endian>*
  make_data_plt(Layout* layout,
		Arm_output_data_got<big_endian>* got,
		Output_data_space* got_plt,
		Output_data_space* got_irelative)
  { return this->do_make_data_plt(layout, got, got_plt, got_irelative); }

  // Make an ELF object.
  Object*
  do_make_elf_object(const std::string&, Input_file*, off_t,
		     const elfcpp::Ehdr<32, big_endian>& ehdr);

  Object*
  do_make_elf_object(const std::string&, Input_file*, off_t,
		     const elfcpp::Ehdr<32, !big_endian>&)
  { gold_unreachable(); }

  Object*
  do_make_elf_object(const std::string&, Input_file*, off_t,
		      const elfcpp::Ehdr<64, false>&)
  { gold_unreachable(); }

  Object*
  do_make_elf_object(const std::string&, Input_file*, off_t,
		     const elfcpp::Ehdr<64, true>&)
  { gold_unreachable(); }

  // Make an output section.
  Output_section*
  do_make_output_section(const char* name, elfcpp::Elf_Word type,
			 elfcpp::Elf_Xword flags)
  { return new Arm_output_section<big_endian>(name, type, flags); }

  void
  do_adjust_elf_header(unsigned char* view, int len);

  // We only need to generate stubs, and hence perform relaxation if we are
  // not doing relocatable linking.
  bool
  do_may_relax() const
  { return !parameters->options().relocatable(); }

  bool
  do_relax(int, const Input_objects*, Symbol_table*, Layout*, const Task*);

  // Determine whether an object attribute tag takes an integer, a
  // string or both.
  int
  do_attribute_arg_type(int tag) const;

  // Reorder tags during output.
  int
  do_attributes_order(int num) const;

  // This is called when the target is selected as the default.
  void
  do_select_as_default_target()
  {
    // No locking is required since there should only be one default target.
    // We cannot have both the big-endian and little-endian ARM targets
    // as the default.
    gold_assert(arm_reloc_property_table == NULL);
    arm_reloc_property_table = new Arm_reloc_property_table();
    if (parameters->options().user_set_target1_rel())
      {
	// FIXME: This is not strictly compatible with ld, which allows both
	// --target1-abs and --target-rel to be given.
	if (parameters->options().user_set_target1_abs())
	  gold_error(_("Cannot use both --target1-abs and --target1-rel."));
	else
	  this->target1_reloc_ = elfcpp::R_ARM_REL32;
      }
    // We don't need to handle --target1-abs because target1_reloc_ is set
    // to elfcpp::R_ARM_ABS32 in the member initializer list.

    if (parameters->options().user_set_target2())
      {
	const char* target2 = parameters->options().target2();
	if (strcmp(target2, "rel") == 0)
	  this->target2_reloc_ = elfcpp::R_ARM_REL32;
	else if (strcmp(target2, "abs") == 0)
	  this->target2_reloc_ = elfcpp::R_ARM_ABS32;
	else if (strcmp(target2, "got-rel") == 0)
	  this->target2_reloc_ = elfcpp::R_ARM_GOT_PREL;
	else
	  gold_unreachable();
      }
  }

  // Virtual function which is set to return true by a target if
  // it can use relocation types to determine if a function's
  // pointer is taken.
  virtual bool
  do_can_check_for_function_pointers() const
  { return true; }

  // Whether a section called SECTION_NAME may have function pointers to
  // sections not eligible for safe ICF folding.
  virtual bool
  do_section_may_have_icf_unsafe_pointers(const char* section_name) const
  {
    return (!is_prefix_of(".ARM.exidx", section_name)
	    && !is_prefix_of(".ARM.extab", section_name)
	    && Target::do_section_may_have_icf_unsafe_pointers(section_name));
  }

  virtual void
  do_define_standard_symbols(Symbol_table*, Layout*);

  virtual Output_data_plt_arm<big_endian>*
  do_make_data_plt(Layout* layout,
		   Arm_output_data_got<big_endian>* got,
		   Output_data_space* got_plt,
		   Output_data_space* got_irelative)
  {
    gold_assert(got_plt != NULL && got_irelative != NULL);
    if (parameters->options().long_plt())
      return new Output_data_plt_arm_long<big_endian>(
	layout, got, got_plt, got_irelative);
    else
      return new Output_data_plt_arm_short<big_endian>(
	layout, got, got_plt, got_irelative);
  }

 private:
  // The class which scans relocations.
  class Scan
  {
   public:
    Scan()
      : issued_non_pic_error_(false)
    { }

    static inline int
    get_reference_flags(unsigned int r_type);

    inline void
    local(Symbol_table* symtab, Layout* layout, Target_arm* target,
	  Sized_relobj_file<32, big_endian>* object,
	  unsigned int data_shndx,
	  Output_section* output_section,
	  const elfcpp::Rel<32, big_endian>& reloc, unsigned int r_type,
	  const elfcpp::Sym<32, big_endian>& lsym,
	  bool is_discarded);

    inline void
    global(Symbol_table* symtab, Layout* layout, Target_arm* target,
	   Sized_relobj_file<32, big_endian>* object,
	   unsigned int data_shndx,
	   Output_section* output_section,
	   const elfcpp::Rel<32, big_endian>& reloc, unsigned int r_type,
	   Symbol* gsym);

    inline bool
    local_reloc_may_be_function_pointer(Symbol_table* , Layout* , Target_arm* ,
					Sized_relobj_file<32, big_endian>* ,
					unsigned int ,
					Output_section* ,
					const elfcpp::Rel<32, big_endian>& ,
					unsigned int ,
					const elfcpp::Sym<32, big_endian>&);

    inline bool
    global_reloc_may_be_function_pointer(Symbol_table* , Layout* , Target_arm* ,
					 Sized_relobj_file<32, big_endian>* ,
					 unsigned int ,
					 Output_section* ,
					 const elfcpp::Rel<32, big_endian>& ,
					 unsigned int , Symbol*);

   private:
    static void
    unsupported_reloc_local(Sized_relobj_file<32, big_endian>*,
			    unsigned int r_type);

    static void
    unsupported_reloc_global(Sized_relobj_file<32, big_endian>*,
			     unsigned int r_type, Symbol*);

    void
    check_non_pic(Relobj*, unsigned int r_type);

    // Almost identical to Symbol::needs_plt_entry except that it also
    // handles STT_ARM_TFUNC.
    static bool
    symbol_needs_plt_entry(const Symbol* sym)
    {
      // An undefined symbol from an executable does not need a PLT entry.
      if (sym->is_undefined() && !parameters->options().shared())
	return false;

      if (sym->type() == elfcpp::STT_GNU_IFUNC)
	return true;

      return (!parameters->doing_static_link()
	      && (sym->type() == elfcpp::STT_FUNC
		  || sym->type() == elfcpp::STT_ARM_TFUNC)
	      && (sym->is_from_dynobj()
		  || sym->is_undefined()
		  || sym->is_preemptible()));
    }

    inline bool
    possible_function_pointer_reloc(unsigned int r_type);

    // Whether a plt entry is needed for ifunc.
    bool
    reloc_needs_plt_for_ifunc(Sized_relobj_file<32, big_endian>*,
			      unsigned int r_type);

    // Whether we have issued an error about a non-PIC compilation.
    bool issued_non_pic_error_;
  };

  // The class which implements relocation.
  class Relocate
  {
   public:
    Relocate()
    { }

    ~Relocate()
    { }

    // Return whether the static relocation needs to be applied.
    inline bool
    should_apply_static_reloc(const Sized_symbol<32>* gsym,
			      unsigned int r_type,
			      bool is_32bit,
			      Output_section* output_section);

    // Do a relocation.  Return false if the caller should not issue
    // any warnings about this relocation.
    inline bool
    relocate(const Relocate_info<32, big_endian>*, unsigned int,
	     Target_arm*, Output_section*, size_t, const unsigned char*,
	     const Sized_symbol<32>*, const Symbol_value<32>*,
	     unsigned char*, Arm_address, section_size_type);

    // Return whether we want to pass flag NON_PIC_REF for this
    // reloc.  This means the relocation type accesses a symbol not via
    // GOT or PLT.
    static inline bool
    reloc_is_non_pic(unsigned int r_type)
    {
      switch (r_type)
	{
	// These relocation types reference GOT or PLT entries explicitly.
	case elfcpp::R_ARM_GOT_BREL:
	case elfcpp::R_ARM_GOT_ABS:
	case elfcpp::R_ARM_GOT_PREL:
	case elfcpp::R_ARM_GOT_BREL12:
	case elfcpp::R_ARM_PLT32_ABS:
	case elfcpp::R_ARM_TLS_GD32:
	case elfcpp::R_ARM_TLS_LDM32:
	case elfcpp::R_ARM_TLS_IE32:
	case elfcpp::R_ARM_TLS_IE12GP:

	// These relocate types may use PLT entries.
	case elfcpp::R_ARM_CALL:
	case elfcpp::R_ARM_THM_CALL:
	case elfcpp::R_ARM_JUMP24:
	case elfcpp::R_ARM_THM_JUMP24:
	case elfcpp::R_ARM_THM_JUMP19:
	case elfcpp::R_ARM_PLT32:
	case elfcpp::R_ARM_THM_XPC22:
	case elfcpp::R_ARM_PREL31:
	case elfcpp::R_ARM_SBREL31:
	  return false;

	default:
	  return true;
	}
    }

   private:
    // Do a TLS relocation.
    inline typename Arm_relocate_functions<big_endian>::Status
    relocate_tls(const Relocate_info<32, big_endian>*, Target_arm<big_endian>*,
		 size_t, const elfcpp::Rel<32, big_endian>&, unsigned int,
		 const Sized_symbol<32>*, const Symbol_value<32>*,
		 unsigned char*, elfcpp::Elf_types<32>::Elf_Addr,
		 section_size_type);

  };

  // A class for inquiring about properties of a relocation,
  // used while scanning relocs during a relocatable link and
  // garbage collection.
  class Classify_reloc :
      public gold::Default_classify_reloc<elfcpp::SHT_REL, 32, big_endian>
  {
   public:
    typedef typename Reloc_types<elfcpp::SHT_REL, 32, big_endian>::Reloc
	Reltype;

    // Return the explicit addend of the relocation (return 0 for SHT_REL).
    static typename elfcpp::Elf_types<32>::Elf_Swxword
    get_r_addend(const Reltype*)
    { return 0; }

    // Return the size of the addend of the relocation (only used for SHT_REL).
    static unsigned int
    get_size_for_reloc(unsigned int, Relobj*);
  };

  // Adjust TLS relocation type based on the options and whether this
  // is a local symbol.
  static tls::Tls_optimization
  optimize_tls_reloc(bool is_final, int r_type);

  // Get the GOT section, creating it if necessary.
  Arm_output_data_got<big_endian>*
  got_section(Symbol_table*, Layout*);

  // Get the GOT PLT section.
  Output_data_space*
  got_plt_section() const
  {
    gold_assert(this->got_plt_ != NULL);
    return this->got_plt_;
  }

  // Create the PLT section.
  void
  make_plt_section(Symbol_table* symtab, Layout* layout);

  // Create a PLT entry for a global symbol.
  void
  make_plt_entry(Symbol_table*, Layout*, Symbol*);

  // Create a PLT entry for a local STT_GNU_IFUNC symbol.
  void
  make_local_ifunc_plt_entry(Symbol_table*, Layout*,
			     Sized_relobj_file<32, big_endian>* relobj,
			     unsigned int local_sym_index);

  // Define the _TLS_MODULE_BASE_ symbol in the TLS segment.
  void
  define_tls_base_symbol(Symbol_table*, Layout*);

  // Create a GOT entry for the TLS module index.
  unsigned int
  got_mod_index_entry(Symbol_table* symtab, Layout* layout,
		      Sized_relobj_file<32, big_endian>* object);

  // Get the PLT section.
  const Output_data_plt_arm<big_endian>*
  plt_section() const
  {
    gold_assert(this->plt_ != NULL);
    return this->plt_;
  }

  // Get the dynamic reloc section, creating it if necessary.
  Reloc_section*
  rel_dyn_section(Layout*);

  // Get the section to use for TLS_DESC relocations.
  Reloc_section*
  rel_tls_desc_section(Layout*) const;

  // Return true if the symbol may need a COPY relocation.
  // References from an executable object to non-function symbols
  // defined in a dynamic object may need a COPY relocation.
  bool
  may_need_copy_reloc(Symbol* gsym)
  {
    return (gsym->type() != elfcpp::STT_ARM_TFUNC
	    && gsym->may_need_copy_reloc());
  }

  // Add a potential copy relocation.
  void
  copy_reloc(Symbol_table* symtab, Layout* layout,
	     Sized_relobj_file<32, big_endian>* object,
	     unsigned int shndx, Output_section* output_section,
	     Symbol* sym, const elfcpp::Rel<32, big_endian>& reloc)
  {
    unsigned int r_type = elfcpp::elf_r_type<32>(reloc.get_r_info());
    this->copy_relocs_.copy_reloc(symtab, layout,
				  symtab->get_sized_symbol<32>(sym),
				  object, shndx, output_section,
				  r_type, reloc.get_r_offset(), 0,
				  this->rel_dyn_section(layout));
  }

  // Whether two EABI versions are compatible.
  static bool
  are_eabi_versions_compatible(elfcpp::Elf_Word v1, elfcpp::Elf_Word v2);

  // Merge processor-specific flags from input object and those in the ELF
  // header of the output.
  void
  merge_processor_specific_flags(const std::string&, elfcpp::Elf_Word);

  // Get the secondary compatible architecture.
  static int
  get_secondary_compatible_arch(const Attributes_section_data*);

  // Set the secondary compatible architecture.
  static void
  set_secondary_compatible_arch(Attributes_section_data*, int);

  static int
  tag_cpu_arch_combine(const char*, int, int*, int, int);

  // Helper to print AEABI enum tag value.
  static std::string
  aeabi_enum_name(unsigned int);

  // Return string value for TAG_CPU_name.
  static std::string
  tag_cpu_name_value(unsigned int);

  // Query attributes object to see if integer divide instructions may be
  // present in an object.
  static bool
  attributes_accept_div(int arch, int profile,
			const Object_attribute* div_attr);

  // Query attributes object to see if integer divide instructions are
  // forbidden to be in the object.  This is not the inverse of
  // attributes_accept_div.
  static bool
  attributes_forbid_div(const Object_attribute* div_attr);

  // Merge object attributes from input object and those in the output.
  void
  merge_object_attributes(const char*, const Attributes_section_data*);

  // Helper to get an AEABI object attribute
  Object_attribute*
  get_aeabi_object_attribute(int tag) const
  {
    Attributes_section_data* pasd = this->attributes_section_data_;
    gold_assert(pasd != NULL);
    Object_attribute* attr =
      pasd->get_attribute(Object_attribute::OBJ_ATTR_PROC, tag);
    gold_assert(attr != NULL);
    return attr;
  }

  //
  // Methods to support stub-generations.
  //

  // Group input sections for stub generation.
  void
  group_sections(Layout*, section_size_type, bool, const Task*);

  // Scan a relocation for stub generation.
  void
  scan_reloc_for_stub(const Relocate_info<32, big_endian>*, unsigned int,
		      const Sized_symbol<32>*, unsigned int,
		      const Symbol_value<32>*,
		      elfcpp::Elf_types<32>::Elf_Swxword, Arm_address);

  // Scan a relocation section for stub.
  template<int sh_type>
  void
  scan_reloc_section_for_stubs(
      const Relocate_info<32, big_endian>* relinfo,
      const unsigned char* prelocs,
      size_t reloc_count,
      Output_section* output_section,
      bool needs_special_offset_handling,
      const unsigned char* view,
      elfcpp::Elf_types<32>::Elf_Addr view_address,
      section_size_type);

  // Fix .ARM.exidx section coverage.
  void
  fix_exidx_coverage(Layout*, const Input_objects*,
		     Arm_output_section<big_endian>*, Symbol_table*,
		     const Task*);

  // Functors for STL set.
  struct output_section_address_less_than
  {
    bool
    operator()(const Output_section* s1, const Output_section* s2) const
    { return s1->address() < s2->address(); }
  };

  // Information about this specific target which we pass to the
  // general Target structure.
  static const Target::Target_info arm_info;

  // The types of GOT entries needed for this platform.
  // These values are exposed to the ABI in an incremental link.
  // Do not renumber existing values without changing the version
  // number of the .gnu_incremental_inputs section.
  enum Got_type
  {
    GOT_TYPE_STANDARD = 0,      // GOT entry for a regular symbol
    GOT_TYPE_TLS_NOFFSET = 1,   // GOT entry for negative TLS offset
    GOT_TYPE_TLS_OFFSET = 2,    // GOT entry for positive TLS offset
    GOT_TYPE_TLS_PAIR = 3,      // GOT entry for TLS module/offset pair
    GOT_TYPE_TLS_DESC = 4       // GOT entry for TLS_DESC pair
  };

  typedef typename std::vector<Stub_table<big_endian>*> Stub_table_list;

  // Map input section to Arm_input_section.
  typedef Unordered_map<Section_id,
			Arm_input_section<big_endian>*,
			Section_id_hash>
	  Arm_input_section_map;

  // Map output addresses to relocs for Cortex-A8 erratum.
  typedef Unordered_map<Arm_address, const Cortex_a8_reloc*>
	  Cortex_a8_relocs_info;

  // The GOT section.
  Arm_output_data_got<big_endian>* got_;
  // The PLT section.
  Output_data_plt_arm<big_endian>* plt_;
  // The GOT PLT section.
  Output_data_space* got_plt_;
  // The GOT section for IRELATIVE relocations.
  Output_data_space* got_irelative_;
  // The dynamic reloc section.
  Reloc_section* rel_dyn_;
  // The section to use for IRELATIVE relocs.
  Reloc_section* rel_irelative_;
  // Relocs saved to avoid a COPY reloc.
  Copy_relocs<elfcpp::SHT_REL, 32, big_endian> copy_relocs_;
  // Offset of the GOT entry for the TLS module index.
  unsigned int got_mod_index_offset_;
  // True if the _TLS_MODULE_BASE_ symbol has been defined.
  bool tls_base_symbol_defined_;
  // Vector of Stub_tables created.
  Stub_table_list stub_tables_;
  // Stub factory.
  const Stub_factory &stub_factory_;
  // Whether we force PIC branch veneers.
  bool should_force_pic_veneer_;
  // Map for locating Arm_input_sections.
  Arm_input_section_map arm_input_section_map_;
  // Attributes section data in output.
  Attributes_section_data* attributes_section_data_;
  // Whether we want to fix code for Cortex-A8 erratum.
  bool fix_cortex_a8_;
  // Map addresses to relocs for Cortex-A8 erratum.
  Cortex_a8_relocs_info cortex_a8_relocs_info_;
  // What R_ARM_TARGET1 maps to. It can be R_ARM_REL32 or R_ARM_ABS32.
  unsigned int target1_reloc_;
  // What R_ARM_TARGET2 maps to. It should be one of R_ARM_REL32, R_ARM_ABS32
  // and R_ARM_GOT_PREL.
  unsigned int target2_reloc_;
};

template<bool big_endian>
const Target::Target_info Target_arm<big_endian>::arm_info =
{
  32,			// size
  big_endian,		// is_big_endian
  elfcpp::EM_ARM,	// machine_code
  false,		// has_make_symbol
  false,		// has_resolve
  false,		// has_code_fill
  true,			// is_default_stack_executable
  false,		// can_icf_inline_merge_sections
  '\0',			// wrap_char
  "/usr/lib/libc.so.1",	// dynamic_linker
  0x8000,		// default_text_segment_address
  0x1000,		// abi_pagesize (overridable by -z max-page-size)
  0x1000,		// common_pagesize (overridable by -z common-page-size)
  false,                // isolate_execinstr
  0,                    // rosegment_gap
  elfcpp::SHN_UNDEF,	// small_common_shndx
  elfcpp::SHN_UNDEF,	// large_common_shndx
  0,			// small_common_section_flags
  0,			// large_common_section_flags
  ".ARM.attributes",	// attributes_section
  "aeabi",		// attributes_vendor
  "_start",		// entry_symbol_name
  32,			// hash_entry_size
  elfcpp::SHT_PROGBITS,	// unwind_section_type
};

// Arm relocate functions class
//

template<bool big_endian>
class Arm_relocate_functions : public Relocate_functions<32, big_endian>
{
 public:
  typedef enum
  {
    STATUS_OKAY,	// No error during relocation.
    STATUS_OVERFLOW,	// Relocation overflow.
    STATUS_BAD_RELOC	// Relocation cannot be applied.
  } Status;

 private:
  typedef Relocate_functions<32, big_endian> Base;
  typedef Arm_relocate_functions<big_endian> This;

  // Encoding of imm16 argument for movt and movw ARM instructions
  // from ARM ARM:
  //
  //     imm16 := imm4 | imm12
  //
  //  f e d c b a 9 8 7 6 5 4 3 2 1 0 f e d c b a 9 8 7 6 5 4 3 2 1 0
  // +-------+---------------+-------+-------+-----------------------+
  // |       |               |imm4   |       |imm12                  |
  // +-------+---------------+-------+-------+-----------------------+

  // Extract the relocation addend from VAL based on the ARM
  // instruction encoding described above.
  static inline typename elfcpp::Swap<32, big_endian>::Valtype
  extract_arm_movw_movt_addend(
      typename elfcpp::Swap<32, big_endian>::Valtype val)
  {
    // According to the Elf ABI for ARM Architecture the immediate
    // field is sign-extended to form the addend.
    return Bits<16>::sign_extend32(((val >> 4) & 0xf000) | (val & 0xfff));
  }

  // Insert X into VAL based on the ARM instruction encoding described
  // above.
  static inline typename elfcpp::Swap<32, big_endian>::Valtype
  insert_val_arm_movw_movt(
      typename elfcpp::Swap<32, big_endian>::Valtype val,
      typename elfcpp::Swap<32, big_endian>::Valtype x)
  {
    val &= 0xfff0f000;
    val |= x & 0x0fff;
    val |= (x & 0xf000) << 4;
    return val;
  }

  // Encoding of imm16 argument for movt and movw Thumb2 instructions
  // from ARM ARM:
  //
  //     imm16 := imm4 | i | imm3 | imm8
  //
  //  f e d c b a 9 8 7 6 5 4 3 2 1 0  f e d c b a 9 8 7 6 5 4 3 2 1 0
  // +---------+-+-----------+-------++-+-----+-------+---------------+
  // |         |i|           |imm4   || |imm3 |       |imm8           |
  // +---------+-+-----------+-------++-+-----+-------+---------------+

  // Extract the relocation addend from VAL based on the Thumb2
  // instruction encoding described above.
  static inline typename elfcpp::Swap<32, big_endian>::Valtype
  extract_thumb_movw_movt_addend(
      typename elfcpp::Swap<32, big_endian>::Valtype val)
  {
    // According to the Elf ABI for ARM Architecture the immediate
    // field is sign-extended to form the addend.
    return Bits<16>::sign_extend32(((val >> 4) & 0xf000)
				   | ((val >> 15) & 0x0800)
				   | ((val >> 4) & 0x0700)
				   | (val & 0x00ff));
  }

  // Insert X into VAL based on the Thumb2 instruction encoding
  // described above.
  static inline typename elfcpp::Swap<32, big_endian>::Valtype
  insert_val_thumb_movw_movt(
      typename elfcpp::Swap<32, big_endian>::Valtype val,
      typename elfcpp::Swap<32, big_endian>::Valtype x)
  {
    val &= 0xfbf08f00;
    val |= (x & 0xf000) << 4;
    val |= (x & 0x0800) << 15;
    val |= (x & 0x0700) << 4;
    val |= (x & 0x00ff);
    return val;
  }

  // Calculate the smallest constant Kn for the specified residual.
  // (see (AAELF 4.6.1.4 Static ARM relocations, Group Relocations, p.32)
  static uint32_t
  calc_grp_kn(typename elfcpp::Swap<32, big_endian>::Valtype residual)
  {
    int32_t msb;

    if (residual == 0)
      return 0;
    // Determine the most significant bit in the residual and
    // align the resulting value to a 2-bit boundary.
    for (msb = 30; (msb >= 0) && !(residual & (3 << msb)); msb -= 2)
      ;
    // The desired shift is now (msb - 6), or zero, whichever
    // is the greater.
    return (((msb - 6) < 0) ? 0 : (msb - 6));
  }

  // Calculate the final residual for the specified group index.
  // If the passed group index is less than zero, the method will return
  // the value of the specified residual without any change.
  // (see (AAELF 4.6.1.4 Static ARM relocations, Group Relocations, p.32)
  static typename elfcpp::Swap<32, big_endian>::Valtype
  calc_grp_residual(typename elfcpp::Swap<32, big_endian>::Valtype residual,
		    const int group)
  {
    for (int n = 0; n <= group; n++)<