gold/script-sections.cc

// script-sections.cc -- linker script SECTIONS for gold

// Copyright (C) 2008-2024 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.

// 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 <algorithm>
#include <list>
#include <map>
#include <string>
#include <vector>
#include <fnmatch.h>

#include "parameters.h"
#include "object.h"
#include "layout.h"
#include "output.h"
#include "script-c.h"
#include "script.h"
#include "script-sections.h"

// Support for the SECTIONS clause in linker scripts.

namespace gold
{

// A region of memory.
class Memory_region
{
 public:
  Memory_region(const char* name, size_t namelen, unsigned int attributes,
		Expression* start, Expression* length)
    : name_(name, namelen),
      attributes_(attributes),
      start_(start),
      length_(length),
      current_offset_(0),
      vma_sections_(),
      lma_sections_(),
      last_section_(NULL)
  { }

  // Return the name of this region.
  const std::string&
  name() const
  { return this->name_; }

  // Return the start address of this region.
  Expression*
  start_address() const
  { return this->start_; }

  // Return the length of this region.
  Expression*
  length() const
  { return this->length_; }

  // Print the region (when debugging).
  void
  print(FILE*) const;

  // Return true if <name,namelen> matches this region.
  bool
  name_match(const char* name, size_t namelen)
  {
    return (this->name_.length() == namelen
	    && strncmp(this->name_.c_str(), name, namelen) == 0);
  }

  Expression*
  get_current_address() const
  {
    return
      script_exp_binary_add(this->start_,
			    script_exp_integer(this->current_offset_));
  }

  void
  set_address(uint64_t addr, const Symbol_table* symtab, const Layout* layout)
  {
    uint64_t start = this->start_->eval(symtab, layout, false);
    uint64_t len = this->length_->eval(symtab, layout, false);
    if (addr < start || addr >= start + len)
      gold_error(_("address 0x%llx is not within region %s"),
		 static_cast<unsigned long long>(addr),
		 this->name_.c_str());
    else if (addr < start + this->current_offset_)
      gold_error(_("address 0x%llx moves dot backwards in region %s"),
		 static_cast<unsigned long long>(addr),
		 this->name_.c_str());
    this->current_offset_ = addr - start;
  }

  void
  increment_offset(std::string section_name, uint64_t amount,
		   const Symbol_table* symtab, const Layout* layout)
  {
    this->current_offset_ += amount;

    if (this->current_offset_
	> this->length_->eval(symtab, layout, false))
      gold_error(_("section %s overflows end of region %s"),
		 section_name.c_str(), this->name_.c_str());
  }

  // Returns true iff there is room left in this region
  // for AMOUNT more bytes of data.
  bool
  has_room_for(const Symbol_table* symtab, const Layout* layout,
	       uint64_t amount) const
  {
    return (this->current_offset_ + amount
	    < this->length_->eval(symtab, layout, false));
  }

  // Return true if the provided section flags
  // are compatible with this region's attributes.
  bool
  attributes_compatible(elfcpp::Elf_Xword flags, elfcpp::Elf_Xword type) const;

  void
  add_section(Output_section_definition* sec, bool vma)
  {
    if (vma)
      this->vma_sections_.push_back(sec);
    else
      this->lma_sections_.push_back(sec);
  }

  typedef std::vector<Output_section_definition*> Section_list;

  // Return the start of the list of sections
  // whose VMAs are taken from this region.
  Section_list::const_iterator
  get_vma_section_list_start() const
  { return this->vma_sections_.begin(); }

  // Return the start of the list of sections
  // whose LMAs are taken from this region.
  Section_list::const_iterator
  get_lma_section_list_start() const
  { return this->lma_sections_.begin(); }

  // Return the end of the list of sections
  // whose VMAs are taken from this region.
  Section_list::const_iterator
  get_vma_section_list_end() const
  { return this->vma_sections_.end(); }

  // Return the end of the list of sections
  // whose LMAs are taken from this region.
  Section_list::const_iterator
  get_lma_section_list_end() const
  { return this->lma_sections_.end(); }

  Output_section_definition*
  get_last_section() const
  { return this->last_section_; }

  void
  set_last_section(Output_section_definition* sec)
  { this->last_section_ = sec; }

 private:

  std::string name_;
  unsigned int attributes_;
  Expression* start_;
  Expression* length_;
  // The offset to the next free byte in the region.
  // Note - for compatibility with GNU LD we only maintain one offset
  // regardless of whether the region is being used for VMA values,
  // LMA values, or both.
  uint64_t current_offset_;
  // A list of sections whose VMAs are set inside this region.
  Section_list vma_sections_;
  // A list of sections whose LMAs are set inside this region.
  Section_list lma_sections_;
  // The latest section to make use of this region.
  Output_section_definition* last_section_;
};

// Return true if the provided section flags
// are compatible with this region's attributes.

bool
Memory_region::attributes_compatible(elfcpp::Elf_Xword flags,
				     elfcpp::Elf_Xword type) const
{
  unsigned int attrs = this->attributes_;

  // No attributes means that this region is not compatible with anything.
  if (attrs == 0)
    return false;

  bool match = true;
  do
    {
      switch (attrs & - attrs)
	{
	case MEM_EXECUTABLE:
	  if ((flags & elfcpp::SHF_EXECINSTR) == 0)
	    match = false;
	  break;

	case MEM_WRITEABLE:
	  if ((flags & elfcpp::SHF_WRITE) == 0)
	    match = false;
	  break;

	case MEM_READABLE:
	  // All sections are presumed readable.
	  break;

	case MEM_ALLOCATABLE:
	  if ((flags & elfcpp::SHF_ALLOC) == 0)
	    match = false;
	  break;

	case MEM_INITIALIZED:
	  if ((type & elfcpp::SHT_NOBITS) != 0)
	    match = false;
	  break;
	}
      attrs &= ~ (attrs & - attrs);
    }
  while (attrs != 0);

  return match;
}

// Print a memory region.

void
Memory_region::print(FILE* f) const
{
  fprintf(f, "  %s", this->name_.c_str());

  unsigned int attrs = this->attributes_;
  if (attrs != 0)
    {
      fprintf(f, " (");
      do
	{
	  switch (attrs & - attrs)
	    {
	    case MEM_EXECUTABLE:  fputc('x', f); break;
	    case MEM_WRITEABLE:   fputc('w', f); break;
	    case MEM_READABLE:    fputc('r', f); break;
	    case MEM_ALLOCATABLE: fputc('a', f); break;
	    case MEM_INITIALIZED: fputc('i', f); break;
	    default:
	      gold_unreachable();
	    }
	  attrs &= ~ (attrs & - attrs);
	}
      while (attrs != 0);
      fputc(')', f);
    }

  fprintf(f, " : origin = ");
  this->start_->print(f);
  fprintf(f, ", length = ");
  this->length_->print(f);
  fprintf(f, "\n");
}

// Manage orphan sections.  This is intended to be largely compatible
// with the GNU linker.  The Linux kernel implicitly relies on
// something similar to the GNU linker's orphan placement.  We
// originally used a simpler scheme here, but it caused the kernel
// build to fail, and was also rather inefficient.

class Orphan_section_placement
{
 private:
  typedef Script_sections::Elements_iterator Elements_iterator;

 public:
  Orphan_section_placement();

  // Handle an output section during initialization of this mapping.
  void
  output_section_init(const std::string& name, Output_section*,
		      Elements_iterator location);

  // Initialize the last location.
  void
  last_init(Elements_iterator location);

  // Set *PWHERE to the address of an iterator pointing to the
  // location to use for an orphan section.  Return true if the
  // iterator has a value, false otherwise.
  bool
  find_place(Output_section*, Elements_iterator** pwhere);

  // Update PLACE_LAST_ALLOC.
  void
  update_last_alloc(Elements_iterator where);

  // Return the iterator being used for sections at the very end of
  // the linker script.
  Elements_iterator
  last_place() const;

 private:
  // The places that we specifically recognize.  This list is copied
  // from the GNU linker.
  enum Place_index
  {
    PLACE_TEXT,
    PLACE_RODATA,
    PLACE_DATA,
    PLACE_TLS,
    PLACE_TLS_BSS,
    PLACE_BSS,
    PLACE_LAST_ALLOC,
    PLACE_REL,
    PLACE_INTERP,
    PLACE_NONALLOC,
    PLACE_LAST,
    PLACE_MAX
  };

  // The information we keep for a specific place.
  struct Place
  {
    // The name of sections for this place.
    const char* name;
    // Whether we have a location for this place.
    bool have_location;
    // The iterator for this place.
    Elements_iterator location;
  };

  // Initialize one place element.
  void
  initialize_place(Place_index, const char*);

  // The places.
  Place places_[PLACE_MAX];
  // True if this is the first call to output_section_init.
  bool first_init_;
};

// Initialize Orphan_section_placement.

Orphan_section_placement::Orphan_section_placement()
  : first_init_(true)
{
  this->initialize_place(PLACE_TEXT, ".text");
  this->initialize_place(PLACE_RODATA, ".rodata");
  this->initialize_place(PLACE_DATA, ".data");
  this->initialize_place(PLACE_TLS, NULL);
  this->initialize_place(PLACE_TLS_BSS, NULL);
  this->initialize_place(PLACE_BSS, ".bss");
  this->initialize_place(PLACE_LAST_ALLOC, NULL);
  this->initialize_place(PLACE_REL, NULL);
  this->initialize_place(PLACE_INTERP, ".interp");
  this->initialize_place(PLACE_NONALLOC, NULL);
  this->initialize_place(PLACE_LAST, NULL);
}

// Initialize one place element.

void
Orphan_section_placement::initialize_place(Place_index index, const char* name)
{
  this->places_[index].name = name;
  this->places_[index].have_location = false;
}

// While initializing the Orphan_section_placement information, this
// is called once for each output section named in the linker script.
// If we found an output section during the link, it will be passed in
// OS.

void
Orphan_section_placement::output_section_init(const std::string& name,
					      Output_section* os,
					      Elements_iterator location)
{
  bool first_init = this->first_init_;
  this->first_init_ = false;

  // Remember the last allocated section. Any orphan bss sections
  // will be placed after it.
  if (os != NULL
      && (os->flags() & elfcpp::SHF_ALLOC) != 0)
    {
      this->places_[PLACE_LAST_ALLOC].location = location;
      this->places_[PLACE_LAST_ALLOC].have_location = true;
    }

  for (int i = 0; i < PLACE_MAX; ++i)
    {
      if (this->places_[i].name != NULL && this->places_[i].name == name)
	{
	  if (this->places_[i].have_location)
	    {
	      // We have already seen a section with this name.
	      return;
	    }

	  this->places_[i].location = location;
	  this->places_[i].have_location = true;

	  // If we just found the .bss section, restart the search for
	  // an unallocated section.  This follows the GNU linker's
	  // behaviour.
	  if (i == PLACE_BSS)
	    this->places_[PLACE_NONALLOC].have_location = false;

	  return;
	}
    }

  // Relocation sections.
  if (!this->places_[PLACE_REL].have_location
      && os != NULL
      && (os->type() == elfcpp::SHT_REL || os->type() == elfcpp::SHT_RELA)
      && (os->flags() & elfcpp::SHF_ALLOC) != 0)
    {
      this->places_[PLACE_REL].location = location;
      this->places_[PLACE_REL].have_location = true;
    }

  // We find the location for unallocated sections by finding the
  // first debugging or comment section after the BSS section (if
  // there is one).
  if (!this->places_[PLACE_NONALLOC].have_location
      && (name == ".comment" || Layout::is_debug_info_section(name.c_str())))
    {
      // We add orphan sections after the location in PLACES_.  We
      // want to store unallocated sections before LOCATION.  If this
      // is the very first section, we can't use it.
      if (!first_init)
	{
	  --location;
	  this->places_[PLACE_NONALLOC].location = location;
	  this->places_[PLACE_NONALLOC].have_location = true;
	}
    }
}

// Initialize the last location.

void
Orphan_section_placement::last_init(Elements_iterator location)
{
  this->places_[PLACE_LAST].location = location;
  this->places_[PLACE_LAST].have_location = true;
}

// Set *PWHERE to the address of an iterator pointing to the location
// to use for an orphan section.  Return true if the iterator has a
// value, false otherwise.

bool
Orphan_section_placement::find_place(Output_section* os,
				     Elements_iterator** pwhere)
{
  // Figure out where OS should go.  This is based on the GNU linker
  // code.  FIXME: The GNU linker handles small data sections
  // specially, but we don't.
  elfcpp::Elf_Word type = os->type();
  elfcpp::Elf_Xword flags = os->flags();
  Place_index index;
  if ((flags & elfcpp::SHF_ALLOC) == 0
      && !Layout::is_debug_info_section(os->name()))
    index = PLACE_NONALLOC;
  else if ((flags & elfcpp::SHF_ALLOC) == 0)
    index = PLACE_LAST;
  else if (type == elfcpp::SHT_NOTE)
    index = PLACE_INTERP;
  else if ((flags & elfcpp::SHF_TLS) != 0)
    {
      if (type == elfcpp::SHT_NOBITS)
	index = PLACE_TLS_BSS;
      else
	index = PLACE_TLS;
    }
  else if (type == elfcpp::SHT_NOBITS)
    index = PLACE_BSS;
  else if ((flags & elfcpp::SHF_WRITE) != 0)
    index = PLACE_DATA;
  else if (type == elfcpp::SHT_REL || type == elfcpp::SHT_RELA)
    index = PLACE_REL;
  else if ((flags & elfcpp::SHF_EXECINSTR) == 0)
    index = PLACE_RODATA;
  else
    index = PLACE_TEXT;

  // If we don't have a location yet, try to find one based on a
  // plausible ordering of sections.
  if (!this->places_[index].have_location)
    {
      Place_index follow;
      switch (index)
	{
	default:
	  follow = PLACE_MAX;
	  break;
	case PLACE_RODATA:
	  follow = PLACE_TEXT;
	  break;
	case PLACE_DATA:
	  follow = PLACE_RODATA;
	  if (!this->places_[PLACE_RODATA].have_location)
	    follow = PLACE_TEXT;
	  break;
	case PLACE_BSS:
	  follow = PLACE_LAST_ALLOC;
	  break;
	case PLACE_REL:
	  follow = PLACE_TEXT;
	  break;
	case PLACE_INTERP:
	  follow = PLACE_TEXT;
	  break;
	case PLACE_TLS:
	  follow = PLACE_DATA;
	  break;
	case PLACE_TLS_BSS:
	  follow = PLACE_TLS;
	  if (!this->places_[PLACE_TLS].have_location)
	    follow = PLACE_DATA;
	  break;
	}
      if (follow != PLACE_MAX && this->places_[follow].have_location)
	{
	  // Set the location of INDEX to the location of FOLLOW.  The
	  // location of INDEX will then be incremented by the caller,
	  // so anything in INDEX will continue to be after anything
	  // in FOLLOW.
	  this->places_[index].location = this->places_[follow].location;
	  this->places_[index].have_location = true;
	}
    }

  *pwhere = &this->places_[index].location;
  bool ret = this->places_[index].have_location;

  // The caller will set the location.
  this->places_[index].have_location = true;

  return ret;
}

// Update PLACE_LAST_ALLOC.
void
Orphan_section_placement::update_last_alloc(Elements_iterator elem)
{
  Elements_iterator prev = elem;
  --prev;
  if (this->places_[PLACE_LAST_ALLOC].have_location
      && this->places_[PLACE_LAST_ALLOC].location == prev)
    {
      this->places_[PLACE_LAST_ALLOC].have_location = true;
      this->places_[PLACE_LAST_ALLOC].location = elem;
    }
}

// Return the iterator being used for sections at the very end of the
// linker script.

Orphan_section_placement::Elements_iterator
Orphan_section_placement::last_place() const
{
  gold_assert(this->places_[PLACE_LAST].have_location);
  return this->places_[PLACE_LAST].location;
}

// An element in a SECTIONS clause.

class Sections_element
{
 public:
  Sections_element()
  { }

  virtual ~Sections_element()
  { }

  // Return whether an output section is relro.
  virtual bool
  is_relro() const
  { return false; }

  // Record that an output section is relro.
  virtual void
  set_is_relro()
  { }

  // Create any required output sections.  The only real
  // implementation is in Output_section_definition.
  virtual void
  create_sections(Layout*)
  { }

  // Add any symbol being defined to the symbol table.
  virtual void
  add_symbols_to_table(Symbol_table*)
  { }

  // Finalize symbols and check assertions.
  virtual void
  finalize_symbols(Symbol_table*, const Layout*, uint64_t*)
  { }

  // Return the output section name to use for an input file name and
  // section name.  This only real implementation is in
  // Output_section_definition.
  virtual const char*
  output_section_name(const char*, const char*, Output_section***,
		      Script_sections::Section_type*, bool*, bool)
  { return NULL; }

  // Initialize OSP with an output section.
  virtual void
  orphan_section_init(Orphan_section_placement*,
		      Script_sections::Elements_iterator)
  { }

  // Set section addresses.  This includes applying assignments if the
  // expression is an absolute value.
  virtual void
  set_section_addresses(Symbol_table*, Layout*, uint64_t*, uint64_t*,
			uint64_t*)
  { }

  // Check a constraint (ONLY_IF_RO, etc.) on an output section.  If
  // this section is constrained, and the input sections do not match,
  // return the constraint, and set *POSD.
  virtual Section_constraint
  check_constraint(Output_section_definition**)
  { return CONSTRAINT_NONE; }

  // See if this is the alternate output section for a constrained
  // output section.  If it is, transfer the Output_section and return
  // true.  Otherwise return false.
  virtual bool
  alternate_constraint(Output_section_definition*, Section_constraint)
  { return false; }

  // Get the list of segments to use for an allocated section when
  // using a PHDRS clause.  If this is an allocated section, return
  // the Output_section, and set *PHDRS_LIST (the first parameter) to
  // the list of PHDRS to which it should be attached.  If the PHDRS
  // were not specified, don't change *PHDRS_LIST.  When not returning
  // NULL, set *ORPHAN (the second parameter) according to whether
  // this is an orphan section--one that is not mentioned in the
  // linker script.
  virtual Output_section*
  allocate_to_segment(String_list**, bool*)
  { return NULL; }

  // Look for an output section by name and return the address, the
  // load address, the alignment, and the size.  This is used when an
  // expression refers to an output section which was not actually
  // created.  This returns true if the section was found, false
  // otherwise.  The only real definition is for
  // Output_section_definition.
  virtual bool
  get_output_section_info(const char*, uint64_t*, uint64_t*, uint64_t*,
                          uint64_t*) const
  { return false; }

  // Return the associated Output_section if there is one.
  virtual Output_section*
  get_output_section() const
  { return NULL; }

  // Set the section's memory regions.
  virtual void
  set_memory_region(Memory_region*, bool)
  { gold_error(_("Attempt to set a memory region for a non-output section")); }

  // Print the element for debugging purposes.
  virtual void
  print(FILE* f) const = 0;
};

// An assignment in a SECTIONS clause outside of an output section.

class Sections_element_assignment : public Sections_element
{
 public:
  Sections_element_assignment(const char* name, size_t namelen,
			      Expression* val, bool provide, bool hidden)
    : assignment_(name, namelen, false, val, provide, hidden)
  { }

  // Add the symbol to the symbol table.
  void
  add_symbols_to_table(Symbol_table* symtab)
  { this->assignment_.add_to_table(symtab); }

  // Finalize the symbol.
  void
  finalize_symbols(Symbol_table* symtab, const Layout* layout,
		   uint64_t* dot_value)
  {
    this->assignment_.finalize_with_dot(symtab, layout, *dot_value, NULL);
  }

  // Set the section address.  There is no section here, but if the
  // value is absolute, we set the symbol.  This permits us to use
  // absolute symbols when setting dot.
  void
  set_section_addresses(Symbol_table* symtab, Layout* layout,
			uint64_t* dot_value, uint64_t*, uint64_t*)
  {
    this->assignment_.set_if_absolute(symtab, layout, true, *dot_value, NULL);
  }

  // Print for debugging.
  void
  print(FILE* f) const
  {
    fprintf(f, "  ");
    this->assignment_.print(f);
  }

 private:
  Symbol_assignment assignment_;
};

// An assignment to the dot symbol in a SECTIONS clause outside of an
// output section.

class Sections_element_dot_assignment : public Sections_element
{
 public:
  Sections_element_dot_assignment(Expression* val)
    : val_(val)
  { }

  // Finalize the symbol.
  void
  finalize_symbols(Symbol_table* symtab, const Layout* layout,
		   uint64_t* dot_value)
  {
    // We ignore the section of the result because outside of an
    // output section definition the dot symbol is always considered
    // to be absolute.
    *dot_value = this->val_->eval_with_dot(symtab, layout, true, *dot_value,
					   NULL, NULL, NULL, false);
  }

  // Update the dot symbol while setting section addresses.
  void
  set_section_addresses(Symbol_table* symtab, Layout* layout,
			uint64_t* dot_value, uint64_t* dot_alignment,
			uint64_t* load_address)
  {
    *dot_value = this->val_->eval_with_dot(symtab, layout, false, *dot_value,
					   NULL, NULL, dot_alignment, false);
    *load_address = *dot_value;
  }

  // Print for debugging.
  void
  print(FILE* f) const
  {
    fprintf(f, "  . = ");
    this->val_->print(f);
    fprintf(f, "\n");
  }

 private:
  Expression* val_;
};

// An assertion in a SECTIONS clause outside of an output section.

class Sections_element_assertion : public Sections_element
{
 public:
  Sections_element_assertion(Expression* check, const char* message,
			     size_t messagelen)
    : assertion_(check, message, messagelen)
  { }

  // Check the assertion.
  void
  finalize_symbols(Symbol_table* symtab, const Layout* layout, uint64_t*)
  { this->assertion_.check(symtab, layout); }

  // Print for debugging.
  void
  print(FILE* f) const
  {
    fprintf(f, "  ");
    this->assertion_.print(f);
  }

 private:
  Script_assertion assertion_;
};

// An element in an output section in a SECTIONS clause.

class Output_section_element
{
 public:
  // A list of input sections.
  typedef std::list<Output_section::Input_section> Input_section_list;

  Output_section_element()
  { }

  virtual ~Output_section_element()
  { }

  // Return whether this element requires an output section to exist.
  virtual bool
  needs_output_section() const
  { return false; }

  // Add any symbol being defined to the symbol table.
  virtual void
  add_symbols_to_table(Symbol_table*)
  { }

  // Finalize symbols and check assertions.
  virtual void
  finalize_symbols(Symbol_table*, const Layout*, uint64_t*, Output_section**)
  { }

  // Return whether this element matches FILE_NAME and SECTION_NAME.
  // The only real implementation is in Output_section_element_input.
  virtual bool
  match_name(const char*, const char*, bool *) const
  { return false; }

  // Set section addresses.  This includes applying assignments if the
  // expression is an absolute value.
  virtual void
  set_section_addresses(Symbol_table*, Layout*, Output_section*, uint64_t,
			uint64_t*, uint64_t*, Output_section**, std::string*,
			Input_section_list*)
  { }

  // Print the element for debugging purposes.
  virtual void
  print(FILE* f) const = 0;

 protected:
  // Return a fill string that is LENGTH bytes long, filling it with
  // FILL.
  std::string
  get_fill_string(const std::string* fill, section_size_type length) const;
};

std::string
Output_section_element::get_fill_string(const std::string* fill,
					section_size_type length) const
{
  std::string this_fill;
  this_fill.reserve(length);
  while (this_fill.length() + fill->length() <= length)
    this_fill += *fill;
  if (this_fill.length() < length)
    this_fill.append(*fill, 0, length - this_fill.length());
  return this_fill;
}

// A symbol assignment in an output section.

class Output_section_element_assignment : public Output_section_element
{
 public:
  Output_section_element_assignment(const char* name, size_t namelen,
				    Expression* val, bool provide,
				    bool hidden)
    : assignment_(name, namelen, false, val, provide, hidden)
  { }

  // Add the symbol to the symbol table.
  void
  add_symbols_to_table(Symbol_table* symtab)
  { this->assignment_.add_to_table(symtab); }

  // Finalize the symbol.
  void
  finalize_symbols(Symbol_table* symtab, const Layout* layout,
		   uint64_t* dot_value, Output_section** dot_section)
  {
    this->assignment_.finalize_with_dot(symtab, layout, *dot_value,
					*dot_section);
  }

  // Set the section address.  There is no section here, but if the
  // value is absolute, we set the symbol.  This permits us to use
  // absolute symbols when setting dot.
  void
  set_section_addresses(Symbol_table* symtab, Layout* layout, Output_section*,
			uint64_t, uint64_t* dot_value, uint64_t*,
			Output_section** dot_section, std::string*,
			Input_section_list*)
  {
    this->assignment_.set_if_absolute(symtab, layout, true, *dot_value,
				      *dot_section);
  }

  // Print for debugging.
  void
  print(FILE* f) const
  {
    fprintf(f, "    ");
    this->assignment_.print(f);
  }

 private:
  Symbol_assignment assignment_;
};

// An assignment to the dot symbol in an output section.

class Output_section_element_dot_assignment : public Output_section_element
{
 public:
  Output_section_element_dot_assignment(Expression* val)
    : val_(val)
  { }

  // An assignment to dot within an output section is enough to force
  // the output section to exist.
  bool
  needs_output_section() const
  { return true; }

  // Finalize the symbol.
  void
  finalize_symbols(Symbol_table* symtab, const Layout* layout,
		   uint64_t* dot_value, Output_section** dot_section)
  {
    *dot_value = this->val_->eval_with_dot(symtab, layout, true, *dot_value,
					   *dot_section, dot_section, NULL,
					   true);
  }

  // Update the dot symbol while setting section addresses.
  void
  set_section_addresses(Symbol_table* symtab, Layout* layout, Output_section*,
			uint64_t, uint64_t* dot_value, uint64_t*,
			Output_section** dot_section, std::string*,
			Input_section_list*);

  // Print for debugging.
  void
  print(FILE* f) const
  {
    fprintf(f, "    . = ");
    this->val_->print(f);
    fprintf(f, "\n");
  }

 private:
  Expression* val_;
};

// Update the dot symbol while setting section addresses.

void
Output_section_element_dot_assignment::set_section_addresses(
    Symbol_table* symtab,
    Layout* layout,
    Output_section* output_section,
    uint64_t,
    uint64_t* dot_value,
    uint64_t* dot_alignment,
    Output_section** dot_section,
    std::string* fill,
    Input_section_list*)
{
  uint64_t next_dot = this->val_->eval_with_dot(symtab, layout, false,
						*dot_value, *dot_section,
						dot_section, dot_alignment,
						true);
  if (next_dot < *dot_value)
    gold_error(_("dot may not move backward"));
  if (next_dot > *dot_value && output_section != NULL)
    {
      section_size_type length = convert_to_section_size_type(next_dot
							      - *dot_value);
      Output_section_data* posd;
      if (fill->empty())
	posd = new Output_data_zero_fill(length, 0);
      else
	{
	  std::string this_fill = this->get_fill_string(fill, length);
	  posd = new Output_data_const(this_fill, 0);
	}
      output_section->add_output_section_data(posd);
      layout->new_output_section_data_from_script(posd);
    }
  *dot_value = next_dot;
}

// An assertion in an output section.

class Output_section_element_assertion : public Output_section_element
{
 public:
  Output_section_element_assertion(Expression* check, const char* message,
				   size_t messagelen)
    : assertion_(check, message, messagelen)
  { }

  void
  print(FILE* f) const
  {
    fprintf(f, "    ");
    this->assertion_.print(f);
  }

 private:
  Script_assertion assertion_;
};

// We use a special instance of Output_section_data to handle BYTE,
// SHORT, etc.  This permits forward references to symbols in the
// expressions.

class Output_data_expression : public Output_section_data
{
 public:
  Output_data_expression(int size, bool is_signed, Expression* val,
			 const Symbol_table* symtab, const Layout* layout,
			 uint64_t dot_value, Output_section* dot_section)
    : Output_section_data(size, 0, true),
      is_signed_(is_signed), val_(val), symtab_(symtab),
      layout_(layout), dot_value_(dot_value), dot_section_(dot_section)
  { }

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

  // Write the data to a buffer.
  void
  do_write_to_buffer(unsigned char*);

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

 private:
  template<bool big_endian>
  void
  endian_write_to_buffer(uint64_t, unsigned char*);

  bool is_signed_;
  Expression* val_;
  const Symbol_table* symtab_;
  const Layout* layout_;
  uint64_t dot_value_;
  Output_section* dot_section_;
};

// Write the data element to the output file.

void
Output_data_expression::do_write(Output_file* of)
{
  unsigned char* view = of->get_output_view(this->offset(), this->data_size());
  this->write_to_buffer(view);
  of->write_output_view(this->offset(), this->data_size(), view);
}

// Write the data element to a buffer.

void
Output_data_expression::do_write_to_buffer(unsigned char* buf)
{
  uint64_t val = this->val_->eval_with_dot(this->symtab_, this->layout_,
					   true, this->dot_value_,
					   this->dot_section_, NULL, NULL,
					   false);

  if (parameters->target().is_big_endian())
    this->endian_write_to_buffer<true>(val, buf);
  else
    this->endian_write_to_buffer<false>(val, buf);
}

template<bool big_endian>
void
Output_data_expression::endian_write_to_buffer(uint64_t val,
					       unsigned char* buf)
{
  switch (this->data_size())
    {
    case 1:
      elfcpp::Swap_unaligned<8, big_endian>::writeval(buf, val);
      break;
    case 2:
      elfcpp::Swap_unaligned<16, big_endian>::writeval(buf, val);
      break;
    case 4:
      elfcpp::Swap_unaligned<32, big_endian>::writeval(buf, val);
      break;
    case 8:
      if (parameters->target().get_size() == 32)
	{
	  val &= 0xffffffff;
	  if (this->is_signed_ && (val & 0x80000000) != 0)
	    val |= 0xffffffff00000000LL;
	}
      elfcpp::Swap_unaligned<64, big_endian>::writeval(buf, val);
      break;
    default:
      gold_unreachable();
    }
}

// A data item in an output section.

class Output_section_element_data : public Output_section_element
{
 public:
  Output_section_element_data(int size, bool is_signed, Expression* val)
    : size_(size), is_signed_(is_signed), val_(val)
  { }

  // If there is a data item, then we must create an output section.
  bool
  needs_output_section() const
  { return true; }

  // Finalize symbols--we just need to update dot.
  void
  finalize_symbols(Symbol_table*, const Layout*, uint64_t* dot_value,
		   Output_section**)
  { *dot_value += this->size_; }

  // Store the value in the section.
  void
  set_section_addresses(Symbol_table*, Layout*, Output_section*, uint64_t,
			uint64_t* dot_value, uint64_t*, Output_section**,
			std::string*, Input_section_list*);

  // Print for debugging.
  void
  print(FILE*) const;

 private:
  // The size in bytes.
  int size_;
  // Whether the value is signed.
  bool is_signed_;
  // The value.
  Expression* val_;
};

// Store the value in the section.

void
Output_section_element_data::set_section_addresses(
    Symbol_table* symtab,
    Layout* layout,
    Output_section* os,
    uint64_t,
    uint64_t* dot_value,
    uint64_t*,
    Output_section** dot_section,
    std::string*,
    Input_section_list*)
{
  gold_assert(os != NULL);
  Output_data_expression* expression =
    new Output_data_expression(this->size_, this->is_signed_, this->val_,
			       symtab, layout, *dot_value, *dot_section);
  os->add_output_section_data(expression);
  layout->new_output_section_data_from_script(expression);
  *dot_value += this->size_;
}

// Print for debugging.

void
Output_section_element_data::print(FILE* f) const
{
  const char* s;
  switch (this->size_)
    {
    case 1:
      s = "BYTE";
      break;
    case 2:
      s = "SHORT";
      break;
    case 4:
      s = "LONG";
      break;
    case 8:
      if (this->is_signed_)
	s = "SQUAD";
      else
	s = "QUAD";
      break;
    default:
      gold_unreachable();
    }
  fprintf(f, "    %s(", s);
  this->val_->print(f);
  fprintf(f, ")\n");
}

// A fill value setting in an output section.

class Output_section_element_fill : public Output_section_element
{
 public:
  Output_section_element_fill(Expression* val)
    : val_(val)
  { }

  // Update the fill value while setting section addresses.
  void
  set_section_addresses(Symbol_table* symtab, Layout* layout, Output_section*,
			uint64_t, uint64_t* dot_value, uint64_t*,
			Output_section** dot_section,
			std::string* fill, Input_section_list*)
  {
    Output_section* fill_section;
    uint64_t fill_val = this->val_->eval_with_dot(symtab, layout, false,
						  *dot_value, *dot_section,
						  &fill_section, NULL, false);
    if (fill_section != NULL)
      gold_warning(_("fill value is not absolute"));
    // FIXME: The GNU linker supports fill values of arbitrary length.
    unsigned char fill_buff[4];
    elfcpp::Swap_unaligned<32, true>::writeval(fill_buff, fill_val);
    fill->assign(reinterpret_cast<char*>(fill_buff), 4);
  }

  // Print for debugging.
  void
  print(FILE* f) const
  {
    fprintf(f, "    FILL(");
    this->val_->print(f);
    fprintf(f, ")\n");
  }

 private:
  // The new fill value.
  Expression* val_;
};

// An input section specification in an output section

class Output_section_element_input : public Output_section_element
{
 public:
  Output_section_element_input(const Input_section_spec* spec, bool keep);

  // Finalize symbols--just update the value of the dot symbol.
  void
  finalize_symbols(Symbol_table*, const Layout*, uint64_t* dot_value,
		   Output_section** dot_section)
  {
    *dot_value = this->final_dot_value_;
    *dot_section = this->final_dot_section_;
  }

  // See whether we match FILE_NAME and SECTION_NAME as an input section.
  // If we do then also indicate whether the section should be KEPT.
  bool
  match_name(const char* file_name, const char* section_name, bool* keep) const;

  // Set the section address.
  void
  set_section_addresses(Symbol_table* symtab, Layout* layout, Output_section*,
			uint64_t subalign, uint64_t* dot_value, uint64_t*,
			Output_section**, std::string* fill,
			Input_section_list*);

  // Print for debugging.
  void
  print(FILE* f) const;

 private:
  // An input section pattern.
  struct Input_section_pattern
  {
    std::string pattern;
    bool pattern_is_wildcard;
    Sort_wildcard sort;

    Input_section_pattern(const char* patterna, size_t patternlena,
			  Sort_wildcard sorta)
      : pattern(patterna, patternlena),
	pattern_is_wildcard(is_wildcard_string(this->pattern.c_str())),
	sort(sorta)
    { }
  };

  typedef std::vector<Input_section_pattern> Input_section_patterns;

  // Filename_exclusions is a pair of filename pattern and a bool
  // indicating whether the filename is a wildcard.
  typedef std::vector<std::pair<std::string, bool> > Filename_exclusions;

  // Return whether STRING matches PATTERN, where IS_WILDCARD_PATTERN
  // indicates whether this is a wildcard pattern.
  static inline bool
  match(const char* string, const char* pattern, bool is_wildcard_pattern)
  {
    return (is_wildcard_pattern
	    ? fnmatch(pattern, string, 0) == 0
	    : strcmp(string, pattern) == 0);
  }

  // See if we match a file name.
  bool
  match_file_name(const char* file_name) const;

  // The file name pattern.  If this is the empty string, we match all
  // files.
  std::string filename_pattern_;
  // Whether the file name pattern is a wildcard.
  bool filename_is_wildcard_;
  // How the file names should be sorted.  This may only be
  // SORT_WILDCARD_NONE or SORT_WILDCARD_BY_NAME.
  Sort_wildcard filename_sort_;
  // The list of file names to exclude.
  Filename_exclusions filename_exclusions_;
  // The list of input section patterns.
  Input_section_patterns input_section_patterns_;
  // Whether to keep this section when garbage collecting.
  bool keep_;
  // The value of dot after including all matching sections.
  uint64_t final_dot_value_;
  // The section where dot is defined after including all matching
  // sections.
  Output_section* final_dot_section_;
};

// Construct Output_section_element_input.  The parser records strings
// as pointers into a copy of the script file, which will go away when
// parsing is complete.  We make sure they are in std::string objects.

Output_section_element_input::Output_section_element_input(
    const Input_section_spec* spec,
    bool keep)
  : filename_pattern_(),
    filename_is_wildcard_(false),
    filename_sort_(spec->file.sort),
    filename_exclusions_(),
    input_section_patterns_(),
    keep_(keep),
    final_dot_value_(0),
    final_dot_section_(NULL)
{
  // The filename pattern "*" is common, and matches all files.  Turn
  // it into the empty string.
  if (spec->file.name.length != 1 || spec->file.name.value[0] != '*')
    this->filename_pattern_.assign(spec->file.name.value,
				   spec->file.name.length);
  this->filename_is_wildcard_ = is_wildcard_string(this->filename_pattern_.c_str());

  if (spec->input_sections.exclude != NULL)
    {
      for (String_list::const_iterator p =
	     spec->input_sections.exclude->begin();
	   p != spec->input_sections.exclude->end();
	   ++p)
	{
	  bool is_wildcard = is_wildcard_string((*p).c_str());
	  this->filename_exclusions_.push_back(std::make_pair(*p,
							      is_wildcard));
	}
    }

  if (spec->input_sections.sections != NULL)
    {
      Input_section_patterns& isp(this->input_section_patterns_);
      for (String_sort_list::const_iterator p =
	     spec->input_sections.sections->begin();
	   p != spec->input_sections.sections->end();
	   ++p)
	isp.push_back(Input_section_pattern(p->name.value, p->name.length,
					    p->sort));
    }
}

// See whether we match FILE_NAME.

bool
Output_section_element_input::match_file_name(const char* file_name) const
{
  if (!this->filename_pattern_.empty())
    {
      // If we were called with no filename, we refuse to match a
      // pattern which requires a file name.
      if (file_name == NULL)
	return false;

      if (!match(file_name, this->filename_pattern_.c_str(),
		 this->filename_is_wildcard_))
	return false;
    }

  if (file_name != NULL)
    {
      // Now we have to see whether FILE_NAME matches one of the
      // exclusion patterns, if any.
      for (Filename_exclusions::const_iterator p =
	     this->filename_exclusions_.begin();
	   p != this->filename_exclusions_.end();
	   ++p)
	{
	  if (match(file_name, p->first.c_str(), p->second))
	    return false;
	}
    }

  return true;
}

// See whether we match FILE_NAME and SECTION_NAME.  If we do then
// KEEP indicates whether the section should survive garbage collection.

bool
Output_section_element_input::match_name(const char* file_name,
					 const char* section_name,
					 bool *keep) const
{
  if (!this->match_file_name(file_name))
    return false;

  *keep = this->keep_;

  // If there are no section name patterns, then we match.
  if (this->input_section_patterns_.empty())
    return true;

  // See whether we match the section name patterns.
  for (Input_section_patterns::const_iterator p =
	 this->input_section_patterns_.begin();
       p != this->input_section_patterns_.end();
       ++p)
    {
      if (match(section_name, p->pattern.c_str(), p->pattern_is_wildcard))
	return true;
    }

  // We didn't match any section names, so we didn't match.
  return false;
}

// Information we use to sort the input sections.

class Input_section_info
{
 public:
  Input_section_info(const Output_section::Input_section& input_section)
    : input_section_(input_section), section_name_(),
      size_(0), addralign_(1)
  { }

  // Return the simple input section.
  const Output_section::Input_section&
  input_section() const
  { return this->input_section_; }

  // Return the object.
  Relobj*
  relobj() const
  { return this->input_section_.relobj(); }

  // Return the section index.
  unsigned int
  shndx()
  { return this->input_section_.shndx(); }

  // Return the section name.
  const std::string&
  section_name() const
  { return this->section_name_; }

  // Set the section name.
  void
  set_section_name(const std::string name)
  {
    if (is_compressed_debug_section(name.c_str()))
      this->section_name_ = corresponding_uncompressed_section_name(name);
    else
      this->section_name_ = name;
  }

  // Return the section size.
  uint64_t
  size() const
  { return this->size_; }

  // Set the section size.
  void
  set_size(uint64_t size)
  { this->size_ = size; }

  // Return the address alignment.
  uint64_t
  addralign() const
  { return this->addralign_; }

  // Set the address alignment.
  void
  set_addralign(uint64_t addralign)
  { this->addralign_ = addralign; }

 private:
  // Input section, can be a relaxed section.
  Output_section::Input_section input_section_;
  // Name of the section.
  std::string section_name_;
  // Section size.
  uint64_t size_;
  // Address alignment.
  uint64_t addralign_;
};

// A class to sort the input sections.

class Input_section_sorter
{
 public:
  Input_section_sorter(Sort_wildcard filename_sort, Sort_wildcard section_sort)
    : filename_sort_(filename_sort), section_sort_(section_sort)
  { }

  bool
  operator()(const Input_section_info&, const Input_section_info&) const;

 private:
  static unsigned long
  get_init_priority(const char*);

  Sort_wildcard filename_sort_;
  Sort_wildcard section_sort_;
};

// Return a relative priority of the section with the specified NAME
// (a lower value meand a higher priority), or 0 if it should be compared
// with others as strings.
// The implementation of this function is copied from ld/ldlang.c.

unsigned long
Input_section_sorter::get_init_priority(const char* name)
{
  char* end;
  unsigned long init_priority;

  // GCC uses the following section names for the init_priority
  // attribute with numerical values 101 and 65535 inclusive. A
  // lower value means a higher priority.
  //
  // 1: .init_array.NNNN/.fini_array.NNNN: Where NNNN is the
  //    decimal numerical value of the init_priority attribute.
  //    The order of execution in .init_array is forward and
  //    .fini_array is backward.
  // 2: .ctors.NNNN/.dtors.NNNN: Where NNNN is 65535 minus the
  //    decimal numerical value of the init_priority attribute.
  //    The order of execution in .ctors is backward and .dtors
  //    is forward.

  if (strncmp(name, ".init_array.", 12) == 0
      || strncmp(name, ".fini_array.", 12) == 0)
    {
      init_priority = strtoul(name + 12, &end, 10);
      return *end ? 0 : init_priority;
    }
  else if (strncmp(name, ".ctors.", 7) == 0
	   || strncmp(name, ".dtors.", 7) == 0)
    {
      init_priority = strtoul(name + 7, &end, 10);
      return *end ? 0 : 65535 - init_priority;
    }

  return 0;
}

bool
Input_section_sorter::operator()(const Input_section_info& isi1,
				 const Input_section_info& isi2) const
{
  if (this->section_sort_ == SORT_WILDCARD_BY_INIT_PRIORITY)
    {
      unsigned long ip1 = get_init_priority(isi1.section_name().c_str());
      unsigned long ip2 = get_init_priority(isi2.section_name().c_str());
      if (ip1 != 0 && ip2 != 0 && ip1 != ip2)
	return ip1 < ip2;
    }
  if (this->section_sort_ == SORT_WILDCARD_BY_NAME
      || this->section_sort_ == SORT_WILDCARD_BY_NAME_BY_ALIGNMENT
      || (this->section_sort_ == SORT_WILDCARD_BY_ALIGNMENT_BY_NAME
	  && isi1.addralign() == isi2.addralign())
      || this->section_sort_ == SORT_WILDCARD_BY_INIT_PRIORITY)
    {
      if (isi1.section_name() != isi2.section_name())
	return isi1.section_name() < isi2.section_name();
    }
  if (this->section_sort_ == SORT_WILDCARD_BY_ALIGNMENT
      || this->section_sort_ == SORT_WILDCARD_BY_NAME_BY_ALIGNMENT
      || this->section_sort_ == SORT_WILDCARD_BY_ALIGNMENT_BY_NAME)
    {
      if (isi1.addralign() != isi2.addralign())
	return isi1.addralign() < isi2.addralign();
    }
  if (this->filename_sort_ == SORT_WILDCARD_BY_NAME)
    {
      if (isi1.relobj()->name() != isi2.relobj()->name())
	return (isi1.relobj()->name() < isi2.relobj()->name());
    }

  // Otherwise we leave them in the same order.
  return false;
}

// Set the section address.  Look in INPUT_SECTIONS for sections which
// match this spec, sort them as specified, and add them to the output
// section.

void
Output_section_element_input::set_section_addresses(
    Symbol_table*,
    Layout* layout,
    Output_section* output_section,
    uint64_t subalign,
    uint64_t* dot_value,
    uint64_t*,
    Output_section** dot_section,
    std::string* fill,
    Input_section_list* input_sections)
{
  // We build a list of sections which match each
  // Input_section_pattern.

  // If none of the patterns specify a sort option, we throw all
  // matching input sections into a single bin, in the order we
  // find them.  Otherwise, we put matching input sections into
  // a separate bin for each pattern, and sort each one as
  // specified.  Thus, an input section spec like this:
  //   *(.foo .bar)
  // will group all .foo and .bar sections in the order seen,
  // whereas this:
  //   *(.foo) *(.bar)
  // will group all .foo sections followed by all .bar sections.
  // This matches Gnu ld behavior.

  // Things get really weird, though, when you add a sort spec
  // on some, but not all, of the patterns, like this:
  //   *(SORT_BY_NAME(.foo) .bar)
  // We do not attempt to match Gnu ld behavior in this case.

  typedef std::vector<std::vector<Input_section_info> > Matching_sections;
  size_t input_pattern_count = this->input_section_patterns_.size();
  size_t bin_count = 1;
  bool any_patterns_with_sort = false;
  for (size_t i = 0; i < input_pattern_count; ++i)
    {
      const Input_section_pattern& isp(this->input_section_patterns_[i]);
      if (isp.sort != SORT_WILDCARD_NONE)
	any_patterns_with_sort = true;
    }
  if (any_patterns_with_sort)
    bin_count = input_pattern_count;
  Matching_sections matching_sections(bin_count);

  // Look through the list of sections for this output section.  Add
  // each one which matches to one of the elements of
  // MATCHING_SECTIONS.

  Input_section_list::iterator p = input_sections->begin();
  while (p != input_sections->end())
    {
      Relobj* relobj = p->relobj();
      unsigned int shndx = p->shndx();
      Input_section_info isi(*p);

      // Calling section_name and section_addralign is not very
      // efficient.

      // Lock the object so that we can get information about the
      // section.  This is OK since we know we are single-threaded
      // here.
      {
	const Task* task = reinterpret_cast<const Task*>(-1);
	Task_lock_obj<Object> tl(task, relobj);

	isi.set_section_name(relobj->section_name(shndx));
	if (p->is_relaxed_input_section())
	  {
	    // We use current data size because relaxed section sizes may not
	    // have finalized yet.
	    isi.set_size(p->relaxed_input_section()->current_data_size());
	    isi.set_addralign(p->relaxed_input_section()->addralign());
	  }
	else
	  {
	    isi.set_size(relobj->section_size(shndx));
	    isi.set_addralign(relobj->section_addralign(shndx));
	  }
      }

      if (!this->match_file_name(relobj->name().c_str()))
	++p;
      else if (this->input_section_patterns_.empty())
	{
	  matching_sections[0].push_back(isi);
	  p = input_sections->erase(p);
	}
      else
	{
	  size_t i;
	  for (i = 0; i < input_pattern_count; ++i)
	    {
	      const Input_section_pattern&
		isp(this->input_section_patterns_[i]);
	      if (match(isi.section_name().c_str(), isp.pattern.c_str(),
			isp.pattern_is_wildcard))
		break;
	    }

	  if (i >= input_pattern_count)
	    ++p;
	  else
	    {
	      if (i >= bin_count)
		i = 0;
	      matching_sections[i].push_back(isi);
	      p = input_sections->erase(p);
	    }
	}
    }

  // Look through MATCHING_SECTIONS.  Sort each one as specified,
  // using a stable sort so that we get the default order when
  // sections are otherwise equal.  Add each input section to the
  // output section.

  uint64_t dot = *dot_value;
  for (size_t i = 0; i < bin_count; ++i)
    {
      if (matching_sections[i].empty())
	continue;

      gold_assert(output_section != NULL);

      const Input_section_pattern& isp(this->input_section_patterns_[i]);
      if (isp.sort != SORT_WILDCARD_NONE
	  || this->filename_sort_ != SORT_WILDCARD_NONE)
	std::stable_sort(matching_sections[i].begin(),
			 matching_sections[i].end(),
			 Input_section_sorter(this->filename_sort_,
					      isp.sort));

      for (std::vector<Input_section_info>::const_iterator p =
	     matching_sections[i].begin();
	   p != matching_sections[i].end();
	   ++p)
	{
	  // Override the original address alignment if SUBALIGN is specified.
	  // We need to make a copy of the input section to modify the
	  // alignment.
	  Output_section::Input_section sis(p->input_section());

	  uint64_t this_subalign = sis.addralign();
	  if (!sis.is_input_section())
	    sis.output_section_data()->finalize_data_size();
	  uint64_t data_size = sis.data_size();
	  if (subalign > 0)
	    {
	      this_subalign = subalign;
	      sis.set_addralign(subalign);
	    }

	  uint64_t address = align_address(dot, this_subalign);

	  if (address > dot && !fill->empty())
	    {
	      section_size_type length =
		convert_to_section_size_type(address - dot);
	      std::string this_fill = this->get_fill_string(fill, length);
	      Output_section_data* posd = new Output_data_const(this_fill, 0);
	      output_section->add_output_section_data(posd);
	      layout->new_output_section_data_from_script(posd);
	    }

	  output_section->add_script_input_section(sis);
	  dot = address + data_size;
	}
    }

  // An SHF_TLS/SHT_NOBITS section does not take up any
  // address space.
  if (output_section == NULL
      || (output_section->flags() & elfcpp::SHF_TLS) == 0
      || output_section->type() != elfcpp::SHT_NOBITS)
    *dot_value = dot;

  this->final_dot_value_ = *dot_value;
  this->final_dot_section_ = *dot_section;
}

// Print for debugging.

void
Output_section_element_input::print(FILE* f) const
{
  fprintf(f, "    ");

  if (this->keep_)
    fprintf(f, "KEEP(");

  if (!this->filename_pattern_.empty())
    {
      bool need_close_paren = false;
      switch (this->filename_sort_)
	{
	case SORT_WILDCARD_NONE:
	  break;
	case SORT_WILDCARD_BY_NAME:
	  fprintf(f, "SORT_BY_NAME(");
	  need_close_paren = true;
	  break;
	default:
	  gold_unreachable();
	}

      fprintf(f, "%s", this->filename_pattern_.c_str());

      if (need_close_paren)
	fprintf(f, ")");
    }

  if (!this->input_section_patterns_.empty()
      || !this->filename_exclusions_.empty())
    {
      fprintf(f, "(");

      bool need_space = false;
      if (!this->filename_exclusions_.empty())
	{
	  fprintf(f, "EXCLUDE_FILE(");
	  bool need_comma = false;
	  for (Filename_exclusions::const_iterator p =
		 this->filename_exclusions_.begin();
	       p != this->filename_exclusions_.end();
	       ++p)
	    {
	      if (need_comma)
		fprintf(f, ", ");
	      fprintf(f, "%s", p->first.c_str());
	      need_comma = true;
	    }
	  fprintf(f, ")");
	  need_space = true;
	}

      for (Input_section_patterns::const_iterator p =
	     this->input_section_patterns_.begin();
	   p != this->input_section_patterns_.end();
	   ++p)
	{
	  if (need_space)
	    fprintf(f, " ");

	  int close_parens = 0;
	  switch (p->sort)
	    {
	    case SORT_WILDCARD_NONE:
	      break;
	    case SORT_WILDCARD_BY_NAME:
	      fprintf(f, "SORT_BY_NAME(");
	      close_parens = 1;
	      break;
	    case SORT_WILDCARD_BY_ALIGNMENT:
	      fprintf(f, "SORT_BY_ALIGNMENT(");
	      close_parens = 1;
	      break;
	    case SORT_WILDCARD_BY_NAME_BY_ALIGNMENT:
	      fprintf(f, "SORT_BY_NAME(SORT_BY_ALIGNMENT(");
	      close_parens = 2;
	      break;
	    case SORT_WILDCARD_BY_ALIGNMENT_BY_NAME:
	      fprintf(f, "SORT_BY_ALIGNMENT(SORT_BY_NAME(");
	      close_parens = 2;
	      break;
	    case SORT_WILDCARD_BY_INIT_PRIORITY:
	      fprintf(f, "SORT_BY_INIT_PRIORITY(");
	      close_parens = 1;
	      break;
	    default:
	      gold_unreachable();
	    }

	  fprintf(f, "%s", p->pattern.c_str());

	  for (int i = 0; i < close_parens; ++i)
	    fprintf(f, ")");

	  need_space = true;
	}

      fprintf(f, ")");
    }

  if (this->keep_)
    fprintf(f, ")");

  fprintf(f, "\n");
}

// An output section.

class Output_section_definition : public Sections_element
{
 public:
  typedef Output_section_element::Input_section_list Input_section_list;

  Output_section_definition(const char* name, size_t namelen,
			    const Parser_output_section_header* header);

  // Finish the output section with the information in the trailer.
  void
  finish(const Parser_output_section_trailer* trailer);

  // Add a symbol to be defined.
  void
  add_symbol_assignment(const char* name, size_t length, Expression* value,
			bool provide, bool hidden);

  // Add an assignment to the special dot symbol.
  void
  add_dot_assignment(Expression* value);

  // Add an assertion.
  void
  add_assertion(Expression* check, const char* message, size_t messagelen);

  // Add a data item to the current output section.
  void
  add_data(int size, bool is_signed, Expression* val);

  // Add a setting for the fill value.
  void
  add_fill(Expression* val);

  // Add an input section specification.
  void
  add_input_section(const Input_section_spec* spec, bool keep);

  // Return whether the output section is relro.
  bool
  is_relro() const
  { return this->is_relro_; }

  // Record that the output section is relro.
  void
  set_is_relro()
  { this->is_relro_ = true; }

  // Create any required output sections.
  void
  create_sections(Layout*);

  // Add any symbols being defined to the symbol table.
  void
  add_symbols_to_table(Symbol_table* symtab);

  // Finalize symbols and check assertions.
  void
  finalize_symbols(Symbol_table*, const Layout*, uint64_t*);

  // Return the output section name to use for an input file name and
  // section name.
  const char*
  output_section_name(const char* file_name, const char* section_name,
		      Output_section***, Script_sections::Section_type*,
		      bool*, bool);

  // Initialize OSP with an output section.
  void
  orphan_section_init(Orphan_section_placement* osp,
		      Script_sections::Elements_iterator p)
  { osp->output_section_init(this->name_, this->output_section_, p); }

  // Set the section address.
  void
  set_section_addresses(Symbol_table* symtab, Layout* layout,
			uint64_t* dot_value, uint64_t*,
			uint64_t* load_address);

  // Check a constraint (ONLY_IF_RO, etc.) on an output section.  If
  // this section is constrained, and the input sections do not match,
  // return the constraint, and set *POSD.
  Section_constraint
  check_constraint(Output_section_definition** posd);

  // See if this is the alternate output section for a constrained
  // output section.  If it is, transfer the Output_section and return
  // true.  Otherwise return false.
  bool
  alternate_constraint(Output_section_definition*, Section_constraint);

  // Get the list of segments to use for an allocated section when
  // using a PHDRS clause.
  Output_section*
  allocate_to_segment(String_list** phdrs_list, bool* orphan);

  // Look for an output section by name and return the address, the
  // load address, the alignment, and the size.  This is used when an
  // expression refers to an output section which was not actually
  // created.  This returns true if the section was found, false
  // otherwise.
  bool
  get_output_section_info(const char*, uint64_t*, uint64_t*, uint64_t*,
                          uint64_t*) const;

  // Return the associated Output_section if there is one.
  Output_section*
  get_output_section() const
  { return this->output_section_; }

  // Print the contents to the FILE.  This is for debugging.
  void
  print(FILE*) const;

  // Return the output section type if specified or Script_sections::ST_NONE.
  Script_sections::Section_type
  section_type() const;

  // Store the memory region to use.
  void
  set_memory_region(Memory_region*, bool set_vma);

  void
  set_section_vma(Expression* address)
  { this->address_ = address; }

  void
  set_section_lma(Expression* address)
  { this->load_address_ = address; }

  const std::string&
  get_section_name() const
  { return this->name_; }

 private:
  static const char*
  script_section_type_name(Script_section_type);

  typedef std::vector<Output_section_element*> Output_section_elements;

  // The output section name.
  std::string name_;
  // The address.  This may be NULL.
  Expression* address_;
  // The load address.  This may be NULL.
  Expression* load_address_;
  // The alignment.  This may be NULL.
  Expression* align_;
  // The input section alignment.  This may be NULL.
  Expression* subalign_;
  // The constraint, if any.
  Section_constraint constraint_;
  // The fill value.  This may be NULL.
  Expression* fill_;
  // The list of segments this section should go into.  This may be
  // NULL.
  String_list* phdrs_;
  // The list of elements defining the section.
  Output_section_elements elements_;
  // The Output_section created for this definition.  This will be
  // NULL if none was created.
  Output_section* output_section_;
  // The address after it has been evaluated.
  uint64_t evaluated_address_;
  // The load address after it has been evaluated.
  uint64_t evaluated_load_address_;
  // The alignment after it has been evaluated.
  uint64_t evaluated_addralign_;
  // The output section is relro.
  bool is_relro_;
  // The output section type if specified.
  enum Script_section_type script_section_type_;
};

// Constructor.

Output_section_definition::Output_section_definition(
    const char* name,
    size_t namelen,
    const Parser_output_section_header* header)
  : name_(name, namelen),
    address_(header->address),
    load_address_(header->load_address),
    align_(header->align),
    subalign_(header->subalign),
    constraint_(header->constraint),
    fill_(NULL),
    phdrs_(NULL),
    elements_(),
    output_section_(NULL),
    evaluated_address_(0),
    evaluated_load_address_(0),
    evaluated_addralign_(0),
    is_relro_(false),
    script_section_type_(header->section_type)
{
}

// Finish an output section.

void
Output_section_definition::finish(const Parser_output_section_trailer* trailer)
{
  this->fill_ = trailer->fill;
  this->phdrs_ = trailer->phdrs;
}

// Add a symbol to be defined.

void
Output_section_definition::add_symbol_assignment(const char* name,
						 size_t length,
						 Expression* value,
						 bool provide,
						 bool hidden)
{
  Output_section_element* p = new Output_section_element_assignment(name,
								    length,
								    value,
								    provide,
								    hidden);
  this->elements_.push_back(p);
}

// Add an assignment to the special dot symbol.

void
Output_section_definition::add_dot_assignment(Expression* value)
{
  Output_section_element* p = new Output_section_element_dot_assignment(value);
  this->elements_.push_back(p);
}

// Add an assertion.

void
Output_section_definition::add_assertion(Expression* check,
					 const char* message,
					 size_t messagelen)
{
  Output_section_element* p = new Output_section_element_assertion(check,
								   message,
								   messagelen);
  this->elements_.push_back(p);
}

// Add a data item to the current output section.

void
Output_section_definition::add_data(int size, bool is_signed, Expression* val)
{
  Output_section_element* p = new Output_section_element_data(size, is_signed,
							      val);
  this->elements_.push_back(p);
}

// Add a setting for the fill value.

void
Output_section_definition::add_fill(Expression* val)
{
  Output_section_element* p = new Output_section_element_fill(val);
  this->elements_.push_back(p);
}

// Add an input section specification.

void
Output_section_definition::add_input_section(const Input_section_spec* spec,
					     bool keep)
{
  Output_section_element* p = new Output_section_element_input(spec, keep);
  this->elements_.push_back(p);
}

// Create any required output sections.  We need an output section if
// there is a data statement here.

void
Output_section_definition::create_sections(Layout* layout)
{
  if (this->output_section_ != NULL)
    return;
  for (Output_section_elements::const_iterator p = this->elements_.begin();
       p != this->elements_.end();
       ++p)
    {
      if ((*p)->needs_output_section())
	{
	  const char* name = this->name_.c_str();
	  this->output_section_ =
	    layout->make_output_section_for_script(name, this->section_type());
	  return;
	}
    }
}

// Add any symbols being defined to the symbol table.

void
Output_section_definition::add_symbols_to_table(Symbol_table* symtab)
{
  for (Output_section_elements::iterator p = this->elements_.begin();
       p != this->elements_.end();
       ++p)
    (*p)->add_symbols_to_table(symtab);
}

// Finalize symbols and check assertions.

void
Output_section_definition::finalize_symbols(Symbol_table* symtab,
					    const Layout* layout,
					    uint64_t* dot_value)
{
  if (this->output_section_ != NULL)
    *dot_value = this->output_section_->address();
  else
    {
      uint64_t address = *dot_value;
      if (this->address_ != NULL)
	{
	  address = this->address_->eval_with_dot(symtab, layout, true,
						  *dot_value, NULL,
						  NULL, NULL, false);
	}
      if (this->align_ != NULL)
	{
	  uint64_t align = this->align_->eval_with_dot(symtab, layout, true,
						       *dot_value, NULL,
						       NULL, NULL, false);
	  address = align_address(address, align);
	}
      *dot_value = address;
    }

  Output_section* dot_section = this->output_section_;
  for (Output_section_elements::iterator p = this->elements_.begin();
       p != this->elements_.end();
       ++p)
    (*p)->finalize_symbols(symtab, layout, dot_value, &dot_section);
}

// Return the output section name to use for an input section name.

const char*
Output_section_definition::output_section_name(
    const char* file_name,
    const char* section_name,
    Output_section*** slot,
    Script_sections::Section_type* psection_type,
    bool* keep,
    bool match_input_spec)
{
  // If the section is a linker-created output section, just look for a match
  // on the output section name.
  if (!match_input_spec && this->name_ != "/DISCARD/")
    {
      if (this->name_ != section_name)
	return NULL;
      *slot = &this->output_section_;
      *psection_type = this->section_type();
      return this->name_.c_str();
    }

  // Ask each element whether it matches NAME.
  for (Output_section_elements::const_iterator p = this->elements_.begin();
       p != this->elements_.end();
       ++p)
    {
      if ((*p)->match_name(file_name, section_name, keep))
	{
	  // We found a match for NAME, which means that it should go
	  // into this output section.
	  *slot = &this->output_section_;
	  *psection_type = this->section_type();
	  return this->name_.c_str();
	}
    }

  // We don't know about this section name.
  return NULL;
}

// Return true if memory from START to START + LENGTH is contained
// within a memory region.

bool
Script_sections::block_in_region(Symbol_table* symtab, Layout* layout,
				 uint64_t start, uint64_t length) const
{
  if (this->memory_regions_ == NULL)
    return false;

  for (Memory_regions::const_iterator mr = this->memory_regions_->begin();
       mr != this->memory_regions_->end();
       ++mr)
    {
      uint64_t s = (*mr)->start_address()->eval(symtab, layout, false);
      uint64_t l = (*mr)->length()->eval(symtab, layout, false);

      if (s <= start
	  && (s + l) >= (start + length))
	return true;
    }

  return false;
}

// Find a memory region that should be used by a given output SECTION.
// If provided set PREVIOUS_SECTION_RETURN to point to the last section
// that used the return memory region.

Memory_region*
Script_sections::find_memory_region(
    Output_section_definition* section,
    bool find_vma_region,
    bool explicit_only,
    Output_section_definition** previous_section_return)
{
  if (previous_section_return != NULL)
    * previous_section_return = NULL;

  // Walk the memory regions specified in this script, if any.
  if (this->memory_regions_ == NULL)
    return NULL;

  // The /DISCARD/ section never gets assigned to any region.
  if (section->get_section_name() == "/DISCARD/")
    return NULL;

  Memory_region* first_match = NULL;

  // First check to see if a region has been assigned to this section.
  for (Memory_regions::const_iterator mr = this->memory_regions_->begin();
       mr != this->memory_regions_->end();
       ++mr)
    {
      if (find_vma_region)
	{
	  for (Memory_region::Section_list::const_iterator s =
		 (*mr)->get_vma_section_list_start();
	       s != (*mr)->get_vma_section_list_end();
	       ++s)
	    if ((*s) == section)
	      {
		(*mr)->set_last_section(section);
		return *mr;
	      }
	}
      else
	{
	  for (Memory_region::Section_list::const_iterator s =
		 (*mr)->get_lma_section_list_start();
	       s != (*mr)->get_lma_section_list_end();
	       ++s)
	    if ((*s) == section)
	      {
		(*mr)->set_last_section(section);
		return *mr;
	      }
	}

      if (!explicit_only)
	{
	  // Make a note of the first memory region whose attributes
	  // are compatible with the section.  If we do not find an
	  // explicit region assignment, then we will return this region.
	  Output_section* out_sec = section->get_output_section();
	  if (first_match == NULL
	      && out_sec != NULL
	      && (*mr)->attributes_compatible(out_sec->flags(),
					      out_sec->type()))
	    first_match = *mr;
	}
    }

  // With LMA computations, if an explicit region has not been specified then
  // we will want to set the difference between the VMA and the LMA of the
  // section were searching for to be the same as the difference between the
  // VMA and LMA of the last section to be added to first matched region.
  // Hence, if it was asked for, we return a pointer to the last section
  // known to be used by the first matched region.
  if (first_match != NULL
      && previous_section_return != NULL)
    *previous_section_return = first_match->get_last_section();

  return first_match;
}

// Set the section address.  Note that the OUTPUT_SECTION_ field will
// be NULL if no input sections were mapped to this output section.
// We still have to adjust dot and process symbol assignments.

void
Output_section_definition::set_section_addresses(Symbol_table* symtab,
						 Layout* layout,
						 uint64_t* dot_value,
						 uint64_t* dot_alignment,
                                                 uint64_t* load_address)
{
  Memory_region* vma_region = NULL;
  Memory_region* lma_region = NULL;
  Script_sections* script_sections =
    layout->script_options()->script_sections();
  uint64_t address;
  uint64_t old_dot_value = *dot_value;
  uint64_t old_load_address = *load_address;

  // If input section sorting is requested via --section-ordering-file or
  // linker plugins, then do it here.  This is important because we want
  // any sorting specified in the linker scripts, which will be done after
  // this, to take precedence.  The final order of input sections is then
  // guaranteed to be according to the linker script specification.
  if (this->output_section_ != NULL
      && this->output_section_->input_section_order_specified())
    this->output_section_->sort_attached_input_sections();

  // Decide the start address for the section.  The algorithm is:
  // 1) If an address has been specified in a linker script, use that.
  // 2) Otherwise if a memory region has been specified for the section,
  //    use the next free address in the region.
  // 3) Otherwise if memory regions have been specified find the first
  //    region whose attributes are compatible with this section and
  //    install it into that region.
  // 4) Otherwise use the current location counter.

  if (this->output_section_ != NULL
      // Check for --section-start.
      && parameters->options().section_start(this->output_section_->name(),
					     &address))
    ;
  else if (this->address_ == NULL)
    {
      vma_region = script_sections->find_memory_region(this, true, false, NULL);
      if (vma_region != NULL)
	address = vma_region->get_current_address()->eval(symtab, layout,
							  false);
      else
	address = *dot_value;
    }
  else
    {
      vma_region = script_sections->find_memory_region(this, true, true, NULL);
      address = this->address_->eval_with_dot(symtab, layout, true,
					      *dot_value, NULL, NULL,
					      dot_alignment, false);
      if (vma_region != NULL)
	vma_region->set_address(address, symtab, layout);
    }

  uint64_t align;
  if (this->align_ == NULL)
    {
      if (this->output_section_ == NULL)
	align = 0;
      else
	align = this->output_section_->addralign();
    }
  else
    {
      Output_section* align_section;
      align = this->align_->eval_with_dot(symtab, layout, true, *dot_value,
					  NULL, &align_section, NULL, false);
      if (align_section != NULL)
	gold_warning(_("alignment of section %s is not absolute"),
		     this->name_.c_str());
      if (this->output_section_ != NULL)
	this->output_section_->set_addralign(align);
    }

  uint64_t subalign;
  if (this->subalign_ == NULL)
    subalign = 0;
  else
    {
      Output_section* subalign_section;
      subalign = this->subalign_->eval_with_dot(symtab, layout, true,
						*dot_value, NULL,
						&subalign_section, NULL,
						false);
      if (subalign_section != NULL)
	gold_warning(_("subalign of section %s is not absolute"),
		     this->name_.c_str());

      // Reserve a value of 0 to mean there is no SUBALIGN property.
      if (subalign == 0)
	subalign = 1;

      // The external alignment of the output section must be at least
      // as large as that of the input sections.  If there is no
      // explicit ALIGN property, we set the output section alignment
      // to match the input section alignment.
      if (align < subalign || this->align_ == NULL)
	{
	  align = subalign;
	  this->output_section_->set_addralign(align);
	}
    }

  address = align_address(address, align);

  uint64_t start_address = address;

  *dot_value = address;

  // Except for NOLOAD sections, the address of non-SHF_ALLOC sections is
  // forced to zero, regardless of what the linker script wants.
  if (this->output_section_ != NULL
      && ((this->output_section_->flags() & elfcpp::SHF_ALLOC) != 0
	  || this->output_section_->is_noload()))
    this->output_section_->set_address(address);

  this->evaluated_address_ = address;
  this->evaluated_addralign_ = align;

  uint64_t laddr;

  if (this->load_address_ == NULL)
    {
      Output_section_definition* previous_section;

      // Determine if an LMA region has been set for this section.
      lma_region = script_sections->find_memory_region(this, false, false,
						       &previous_section);

      if (lma_region != NULL)
	{
	  if (previous_section == NULL)
	    // The LMA address was explicitly set to the given region.
	    laddr = lma_region->get_current_address()->eval(symtab, layout,
							    false);
	  else
	    {
	      // We are not going to use the discovered lma_region, so
	      // make sure that we do not update it in the code below.
	      lma_region = NULL;

	      if (this->address_ != NULL || previous_section == this)
		{
		  // Either an explicit VMA address has been set, or an
		  // explicit VMA region has been set, so set the LMA equal to
		  // the VMA.
		  laddr = address;
		}
	      else
		{
		  // The LMA address was not explicitly or implicitly set.
		  //
		  // We have been given the first memory region that is
		  // compatible with the current section and a pointer to the
		  // last section to use this region.  Set the LMA of this
		  // section so that the difference between its' VMA and LMA
		  // is the same as the difference between the VMA and LMA of
		  // the last section in the given region.
		  laddr = address + (previous_section->evaluated_load_address_
				     - previous_section->evaluated_address_);
		}
	    }

	  if (this->output_section_ != NULL)
	    this->output_section_->set_load_address(laddr);
	}
      else
	{
	  // Do not set the load address of the output section, if one exists.
	  // This allows future sections to determine what the load address
	  // should be.  If none is ever set, it will default to being the
	  // same as the vma address.
	  laddr = address;
	}
    }
  else
    {
      laddr = this->load_address_->eval_with_dot(symtab, layout, true,
						 *dot_value,
						 this->output_section_,
						 NULL, NULL, false);
      if (this->output_section_ != NULL)
        this->output_section_->set_load_address(laddr);
    }

  this->evaluated_load_address_ = laddr;

  std::string fill;
  if (this->fill_ != NULL)
    {
      // FIXME: The GNU linker supports fill values of arbitrary
      // length.
      Output_section* fill_section;
      uint64_t fill_val = this->fill_->eval_with_dot(symtab, layout, true,
						     *dot_value,
						     NULL, &fill_section,
						     NULL, false);
      if (fill_section != NULL)
	gold_warning(_("fill of section %s is not absolute"),
		     this->name_.c_str());
      unsigned char fill_buff[4];
      elfcpp::Swap_unaligned<32, true>::writeval(fill_buff, fill_val);
      fill.assign(reinterpret_cast<char*>(fill_buff), 4);
    }

  Input_section_list input_sections;
  if (this->output_section_ != NULL)
    {
      // Get the list of input sections attached to this output
      // section.  This will leave the output section with only
      // Output_section_data entries.
      address += this->output_section_->get_input_sections(address,
							   fill,
							   &input_sections);
      *dot_value = address;
    }

  Output_section* dot_section = this->output_section_;
  for (Output_section_elements::iterator p = this->elements_.begin();
       p != this->elements_.end();
       ++p)
    (*p)->set_section_addresses(symtab, layout, this->output_section_,
				subalign, dot_value, dot_alignment,
				&dot_section, &fill, &input_sections);

  gold_assert(input_sections.empty());

  if (vma_region != NULL)
    {
      // Update the VMA region being used by the section now that we know how
      // big it is.  Use the current address in the region, rather than
      // start_address because that might have been aligned upwards and we
      // need to allow for the padding.
      Expression* addr = vma_region->get_current_address();
      uint64_t size = *dot_value - addr->eval(symtab, layout, false);

      vma_region->increment_offset(this->get_section_name(), size,
				   symtab, layout);
    }

  // If the LMA region is different from the VMA region, then increment the
  // offset there as well.  Note that we use the same "dot_value -
  // start_address" formula that is used in the load_address assignment below.
  if (lma_region != NULL && lma_region != vma_region)
    lma_region->increment_offset(this->get_section_name(),
				 *dot_value - start_address,
				 symtab, layout);

  // Compute the load address for the following section.
  if (this->output_section_ == NULL)
    *load_address = *dot_value;
  else if (this->load_address_ == NULL)
    {
      if (lma_region == NULL)
	*load_address = *dot_value;
      else
	*load_address =
	  lma_region->get_current_address()->eval(symtab, layout, false);
    }
  else
    *load_address = (this->output_section_->load_address()
                     + (*dot_value - start_address));

  if (this->output_section_ != NULL)
    {
      if (this->is_relro_)
	this->output_section_->set_is_relro();
      else
	this->output_section_->clear_is_relro();

      // If this is a NOLOAD section, keep dot and load address unchanged.
      if (this->output_section_->is_noload())
	{
	  *dot_value = old_dot_value;
	  *load_address = old_load_address;
	}
    }
}

// Check a constraint (ONLY_IF_RO, etc.) on an output section.  If
// this section is constrained, and the input sections do not match,
// return the constraint, and set *POSD.

Section_constraint
Output_section_definition::check_constraint(Output_section_definition** posd)
{
  switch (this->constraint_)
    {
    case CONSTRAINT_NONE:
      return CONSTRAINT_NONE;

    case CONSTRAINT_ONLY_IF_RO:
      if (this->output_section_ != NULL
	  && (this->output_section_->flags() & elfcpp::SHF_WRITE) != 0)
	{
	  *posd = this;
	  return CONSTRAINT_ONLY_IF_RO;
	}
      return CONSTRAINT_NONE;

    case CONSTRAINT_ONLY_IF_RW:
      if (this->output_section_ != NULL
	  && (this->output_section_->flags() & elfcpp::SHF_WRITE) == 0)
	{
	  *posd = this;
	  return CONSTRAINT_ONLY_IF_RW;
	}
      return CONSTRAINT_NONE;

    case CONSTRAINT_SPECIAL:
      if (this->output_section_ != NULL)
	gold_error(_("SPECIAL constraints are not implemented"));
      return CONSTRAINT_NONE;

    default:
      gold_unreachable();
    }
}

// See if this is the alternate output section for a constrained
// output section.  If it is, transfer the Output_section and return
// true.  Otherwise return false.

bool
Output_section_definition::alternate_constraint(
    Output_section_definition* posd,
    Section_constraint constraint)
{
  if (this->name_ != posd->name_)
    return false;

  switch (constraint)
    {
    case CONSTRAINT_ONLY_IF_RO:
      if (this->constraint_ != CONSTRAINT_ONLY_IF_RW)
	return false;
      break;

    case CONSTRAINT_ONLY_IF_RW:
      if (this->constraint_ != CONSTRAINT_ONLY_IF_RO)
	return false;
      break;

    default:
      gold_unreachable();
    }

  // We have found the alternate constraint.  We just need to move
  // over the Output_section.  When constraints are used properly,
  // THIS should not have an output_section pointer, as all the input
  // sections should have matched the other definition.

  if (this->output_section_ != NULL)
    gold_error(_("mismatched definition for constrained sections"));

  this->output_section_ = posd->output_section_;
  posd->output_section_ = NULL;

  if (this->is_relro_)
    this->output_section_->set_is_relro();
  else
    this->output_section_->clear_is_relro();

  return true;
}

// Get the list of segments to use for an allocated section when using
// a PHDRS clause.

Output_section*
Output_section_definition::allocate_to_segment(String_list** phdrs_list,
					       bool* orphan)
{
  // Update phdrs_list even if we don't have an output section. It
  // might be used by the following sections.
  if (this->phdrs_ != NULL)
    *phdrs_list = this->phdrs_;

  if (this->output_section_ == NULL)
    return NULL;
  if ((this->output_section_->flags() & elfcpp::SHF_ALLOC) == 0)
    return NULL;
  *orphan = false;
  return this->output_section_;
}

// Look for an output section by name and return the address, the load
// address, the alignment, and the size.  This is used when an
// expression refers to an output section which was not actually
// created.  This returns true if the section was found, false
// otherwise.

bool
Output_section_definition::get_output_section_info(const char* name,
                                                   uint64_t* address,
                                                   uint64_t* load_address,
                                                   uint64_t* addralign,
                                                   uint64_t* size) const
{
  if (this->name_ != name)
    return false;

  if (this->output_section_ != NULL)
    {
      *address = this->output_section_->address();
      if (this->output_section_->has_load_address())
        *load_address = this->output_section_->load_address();
      else
        *load_address = *address;
      *addralign = this->output_section_->addralign();
      *size = this->output_section_->current_data_size();
    }
  else
    {
      *address = this->evaluated_address_;
      *load_address = this->evaluated_load_address_;
      *addralign = this->evaluated_addralign_;
      *size = 0;
    }

  return true;
}

// Print for debugging.

void
Output_section_definition::print(FILE* f) const
{
  fprintf(f, "  %s ", this->name_.c_str());

  if (this->address_ != NULL)
    {
      this->address_->print(f);
      fprintf(f, " ");
    }

  if (this->script_section_type_ != SCRIPT_SECTION_TYPE_NONE)
      fprintf(f, "(%s) ",
	      this->script_section_type_name(this->script_section_type_));

  fprintf(f, ": ");

  if (this->load_address_ != NULL)
    {
      fprintf(f, "AT(");
      this->load_address_->print(f);
      fprintf(f, ") ");
    }

  if (this->align_ != NULL)
    {
      fprintf(f, "ALIGN(");
      this->align_->print(f);
      fprintf(f, ") ");
    }

  if (this->subalign_ != NULL)
    {
      fprintf(f, "SUBALIGN(");
      this->subalign_->print(f);
      fprintf(f, ") ");
    }

  fprintf(f, "{\n");

  for (Output_section_elements::const_iterator p = this->elements_.begin();
       p != this->elements_.end();
       ++p)
    (*p)->print(f);

  fprintf(f, "  }");

  if (this->fill_ != NULL)
    {
      fprintf(f, " = ");
      this->fill_->print(f);
    }

  if (this->phdrs_ != NULL)
    {
      for (String_list::const_iterator p = this->phdrs_->begin();
	   p != this->phdrs_->end();
	   ++p)
	fprintf(f, " :%s", p->c_str());
    }

  fprintf(f, "\n");
}

Script_sections::Section_type
Output_section_definition::section_type() const
{
  switch (this->script_section_type_)
    {
    case SCRIPT_SECTION_TYPE_NONE:
      return Script_sections::ST_NONE;
    case SCRIPT_SECTION_TYPE_NOLOAD:
      return Script_sections::ST_NOLOAD;
    case SCRIPT_SECTION_TYPE_COPY:
    case SCRIPT_SECTION_TYPE_DSECT:
    case SCRIPT_SECTION_TYPE_INFO:
    case SCRIPT_SECTION_TYPE_OVERLAY:
      // There are not really support so we treat them as ST_NONE.  The
      // parse should have issued errors for them already.
      return Script_sections::ST_NONE;
    default:
      gold_unreachable();
    }
}

// Return the name of a script section type.

const char*
Output_section_definition::script_section_type_name(
    Script_section_type script_section_type)
{
  switch (script_section_type)
    {
    case SCRIPT_SECTION_TYPE_NONE:
      return "NONE";
    case SCRIPT_SECTION_TYPE_NOLOAD:
      return "NOLOAD";
    case SCRIPT_SECTION_TYPE_DSECT:
      return "DSECT";
    case SCRIPT_SECTION_TYPE_COPY:
      return "COPY";
    case SCRIPT_SECTION_TYPE_INFO:
      return "INFO";
    case SCRIPT_SECTION_TYPE_OVERLAY:
      return "OVERLAY";
    default:
      gold_unreachable();
    }
}

void
Output_section_definition::set_memory_region(Memory_region* mr, bool set_vma)
{
  gold_assert(mr != NULL);
  // Add the current section to the specified region's list.
  mr->add_section(this, set_vma);
}

// An output section created to hold orphaned input sections.  These
// do not actually appear in linker scripts.  However, for convenience
// when setting the output section addresses, we put a marker to these
// sections in the appropriate place in the list of SECTIONS elements.

class Orphan_output_section : public Sections_element
{
 public:
  Orphan_output_section(Output_section* os)
    : os_(os)
  { }

  // Return whether the orphan output section is relro.  We can just
  // check the output section because we always set the flag, if
  // needed, just after we create the Orphan_output_section.
  bool
  is_relro() const
  { return this->os_->is_relro(); }

  // Initialize OSP with an output section.  This should have been
  // done already.
  void
  orphan_section_init(Orphan_section_placement*,
		      Script_sections::Elements_iterator)
  { gold_unreachable(); }

  // Set section addresses.
  void
  set_section_addresses(Symbol_table*, Layout*, uint64_t*, uint64_t*,
			uint64_t*);

  // Get the list of segments to use for an allocated section when
  // using a PHDRS clause.
  Output_section*
  allocate_to_segment(String_list**, bool*);

  // Return the associated Output_section.
  Output_section*
  get_output_section() const
  { return this->os_; }

  // Print for debugging.
  void
  print(FILE* f) const
  {
    fprintf(f, "  marker for orphaned output section %s\n",
	    this->os_->name());
  }

 private:
  Output_section* os_;
};

// Set section addresses.

void
Orphan_output_section::set_section_addresses(Symbol_table*, Layout*,
					     uint64_t* dot_value,
					     uint64_t*,
                                             uint64_t* load_address)
{
  typedef std::list<Output_section::Input_section> Input_section_list;

  bool have_load_address = *load_address != *dot_value;

  uint64_t address = *dot_value;
  address = align_address(address, this->os_->addralign());

  // If input section sorting is requested via --section-ordering-file or
  // linker plugins, then do it here.  This is important because we want
  // any sorting specified in the linker scripts, which will be done after
  // this, to take precedence.  The final order of input sections is then
  // guaranteed to be according to the linker script specification.
  if (this->os_ != NULL
      && this->os_->input_section_order_specified())
    this->os_->sort_attached_input_sections();

  // For a relocatable link, all orphan sections are put at
  // address 0.  In general we expect all sections to be at
  // address 0 for a relocatable link, but we permit the linker
  // script to override that for specific output sections.
  if (parameters->options().relocatable())
    {
      address = 0;
      *load_address = 0;
      have_load_address = false;
    }

  if ((this->os_->flags() & elfcpp::SHF_ALLOC) != 0)
    {
      this->os_->set_address(address);
      if (have_load_address)
        this->os_->set_load_address(align_address(*load_address,
                                                  this->os_->addralign()));
    }

  Input_section_list input_sections;
  address += this->os_->get_input_sections(address, "", &input_sections);

  for (Input_section_list::iterator p = input_sections.begin();
       p != input_sections.end();
       ++p)
    {
      uint64_t addralign = p->addralign();
      if (!p->is_input_section())
	p->output_section_data()->finalize_data_size();
      uint64_t size = p->data_size();
      address = align_address(address, addralign);
      this->os_->add_script_input_section(*p);
      address += size;
    }

  if (parameters->options().relocatable())
    {
      // For a relocatable link, reset DOT_VALUE to 0.
      *dot_value = 0;
      *load_address = 0;
    }
  else if (this->os_ == NULL
	   || (this->os_->flags() & elfcpp::SHF_TLS) == 0
	   || this->os_->type() != elfcpp::SHT_NOBITS)
    {
      // An SHF_TLS/SHT_NOBITS section does not take up any address space.
      if (!have_load_address)
	*load_address = address;
      else
	*load_address += address - *dot_value;

      *dot_value = address;
    }
}

// Get the list of segments to use for an allocated section when using
// a PHDRS clause.  If this is an allocated section, return the
// Output_section.  We don't change the list of segments.

Output_section*
Orphan_output_section::allocate_to_segment(String_list**, bool* orphan)
{
  if ((this->os_->flags() & elfcpp::SHF_ALLOC) == 0)
    return NULL;
  *orphan = true;
  return this->os_;
}

// Class Phdrs_element.  A program header from a PHDRS clause.

class Phdrs_element
{
 public:
  Phdrs_element(const char* name, size_t namelen, unsigned int type,
		bool includes_filehdr, bool includes_phdrs,
		bool is_flags_valid, unsigned int flags,
		Expression* load_address)
    : name_(name, namelen), type_(type), includes_filehdr_(includes_filehdr),
      includes_phdrs_(includes_phdrs), is_flags_valid_(is_flags_valid),
      flags_(flags), load_address_(load_address), load_address_value_(0),
      segment_(NULL)
  { }

  // Return the name of this segment.
  const std::string&
  name() const
  { return this->name_; }

  // Return the type of the segment.
  unsigned int
  type() const
  { return this->type_; }

  // Whether to include the file header.
  bool
  includes_filehdr() const
  { return this->includes_filehdr_; }

  // Whether to include the program headers.
  bool
  includes_phdrs() const
  { return this->includes_phdrs_; }

  // Return whether there is a load address.
  bool