gdb: add target_ops::supports_displaced_step
[deliverable/binutils-gdb.git] / gold / output.cc
index 55080a1fa0a21134de2d5161a5dc2eec7bf2f8b0..75d2fc354a55fbec400ba6a654901cb6b9df7cf5 100644 (file)
@@ -1,6 +1,6 @@
 // output.cc -- manage the output file for gold
 
-// Copyright 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+// Copyright (C) 2006-2020 Free Software Foundation, Inc.
 // Written by Ian Lance Taylor <iant@google.com>.
 
 // This file is part of gold.
 #include <cerrno>
 #include <fcntl.h>
 #include <unistd.h>
-#include <sys/mman.h>
 #include <sys/stat.h>
 #include <algorithm>
+
+#ifdef HAVE_SYS_MMAN_H
+#include <sys/mman.h>
+#endif
+
 #include "libiberty.h"
 
+#include "dwarf.h"
 #include "parameters.h"
 #include "object.h"
 #include "symtab.h"
 #include "reloc.h"
 #include "merge.h"
 #include "descriptors.h"
+#include "layout.h"
 #include "output.h"
 
+// For systems without mmap support.
+#ifndef HAVE_MMAP
+# define mmap gold_mmap
+# define munmap gold_munmap
+# define mremap gold_mremap
+# ifndef MAP_FAILED
+#  define MAP_FAILED (reinterpret_cast<void*>(-1))
+# endif
+# ifndef PROT_READ
+#  define PROT_READ 0
+# endif
+# ifndef PROT_WRITE
+#  define PROT_WRITE 0
+# endif
+# ifndef MAP_PRIVATE
+#  define MAP_PRIVATE 0
+# endif
+# ifndef MAP_ANONYMOUS
+#  define MAP_ANONYMOUS 0
+# endif
+# ifndef MAP_SHARED
+#  define MAP_SHARED 0
+# endif
+
+# ifndef ENOSYS
+#  define ENOSYS EINVAL
+# endif
+
+static void *
+gold_mmap(void *, size_t, int, int, int, off_t)
+{
+  errno = ENOSYS;
+  return MAP_FAILED;
+}
+
+static int
+gold_munmap(void *, size_t)
+{
+  errno = ENOSYS;
+  return -1;
+}
+
+static void *
+gold_mremap(void *, size_t, size_t, int)
+{
+  errno = ENOSYS;
+  return MAP_FAILED;
+}
+
+#endif
+
+#if defined(HAVE_MMAP) && !defined(HAVE_MREMAP)
+# define mremap gold_mremap
+extern "C" void *gold_mremap(void *, size_t, size_t, int);
+#endif
+
 // Some BSD systems still use MAP_ANON instead of MAP_ANONYMOUS
 #ifndef MAP_ANONYMOUS
 # define MAP_ANONYMOUS  MAP_ANON
 #endif
 
-#ifndef HAVE_POSIX_FALLOCATE
-// A dummy, non general, version of posix_fallocate.  Here we just set
-// the file size and hope that there is enough disk space.  FIXME: We
-// could allocate disk space by walking block by block and writing a
-// zero byte into each block.
-static int
-posix_fallocate(int o, off_t offset, off_t len)
-{
-  return ftruncate(o, offset + len);
-}
-#endif // !defined(HAVE_POSIX_FALLOCATE)
+#ifndef MREMAP_MAYMOVE
+# define MREMAP_MAYMOVE 1
+#endif
+
+// Mingw does not have S_ISLNK.
+#ifndef S_ISLNK
+# define S_ISLNK(mode) 0
+#endif
 
 namespace gold
 {
 
+// A wrapper around posix_fallocate.  If we don't have posix_fallocate,
+// or the --no-posix-fallocate option is set, we try the fallocate
+// system call directly.  If that fails, we use ftruncate to set
+// the file size and hope that there is enough disk space.
+
+static int
+gold_fallocate(int o, off_t offset, off_t len)
+{
+  if (len <= 0)
+    return 0;
+
+#ifdef HAVE_POSIX_FALLOCATE
+  if (parameters->options().posix_fallocate())
+    {
+      int err = ::posix_fallocate(o, offset, len);
+      if (err != EINVAL && err != ENOSYS && err != EOPNOTSUPP)
+       return err;
+    }
+#endif // defined(HAVE_POSIX_FALLOCATE)
+
+#ifdef HAVE_FALLOCATE
+  {
+    int err = ::fallocate(o, 0, offset, len);
+    if (err != EINVAL && err != ENOSYS && err != EOPNOTSUPP)
+      return err;
+  }
+#endif // defined(HAVE_FALLOCATE)
+
+  if (::ftruncate(o, offset + len) < 0)
+    return errno;
+  return 0;
+}
+
 // Output_data variables.
 
 bool Output_data::allocated_sizes_are_fixed;
@@ -280,6 +372,7 @@ Output_segment_headers::Output_segment_headers(
     const Layout::Segment_list& segment_list)
   : segment_list_(segment_list)
 {
+  this->set_current_data_size_for_child(this->do_size());
 }
 
 void
@@ -353,16 +446,14 @@ Output_segment_headers::do_size() const
 
 // Output_file_header methods.
 
-Output_file_header::Output_file_header(const Target* target,
+Output_file_header::Output_file_header(Target* target,
                                       const Symbol_table* symtab,
-                                      const Output_segment_headers* osh,
-                                      const char* entry)
+                                      const Output_segment_headers* osh)
   : target_(target),
     symtab_(symtab),
     segment_header_(osh),
     section_header_(NULL),
-    shstrtab_(NULL),
-    entry_(entry)
+    shstrtab_(NULL)
 {
   this->set_data_size(this->do_size());
 }
@@ -411,7 +502,7 @@ Output_file_header::do_write(Output_file* of)
     }
 }
 
-// Write out the file header with appropriate size and endianess.
+// Write out the file header with appropriate size and endianness.
 
 template<int size, bool big_endian>
 void
@@ -497,27 +588,21 @@ Output_file_header::do_sized_write(Output_file* of)
 
   // Let the target adjust the ELF header, e.g., to set EI_OSABI in
   // the e_ident field.
-  parameters->target().adjust_elf_header(view, ehdr_size);
+  this->target_->adjust_elf_header(view, ehdr_size);
 
   of->write_output_view(0, ehdr_size, view);
 }
 
-// Return the value to use for the entry address.  THIS->ENTRY_ is the
-// symbol specified on the command line, if any.
+// Return the value to use for the entry address.
 
 template<int size>
 typename elfcpp::Elf_types<size>::Elf_Addr
 Output_file_header::entry()
 {
-  const bool should_issue_warning = (this->entry_ != NULL
+  const bool should_issue_warning = (parameters->options().entry() != NULL
                                     && !parameters->options().relocatable()
-                                     && !parameters->options().shared());
-
-  // FIXME: Need to support target specific entry symbol.
-  const char* entry = this->entry_;
-  if (entry == NULL)
-    entry = "_start";
-
+                                    && !parameters->options().shared());
+  const char* entry = parameters->entry();
   Symbol* sym = this->symtab_->lookup(entry);
 
   typename Sized_symbol<size>::Value_type v;
@@ -639,10 +724,11 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::Output_reloc(
     Output_data* od,
     Address address,
     bool is_relative,
-    bool is_symbolless)
+    bool is_symbolless,
+    bool use_plt_offset)
   : address_(address), local_sym_index_(GSYM_CODE), type_(type),
     is_relative_(is_relative), is_symbolless_(is_symbolless),
-    is_section_symbol_(false), shndx_(INVALID_CODE)
+    is_section_symbol_(false), use_plt_offset_(use_plt_offset), shndx_(INVALID_CODE)
 {
   // this->type_ is a bitfield; make sure TYPE fits.
   gold_assert(this->type_ == type);
@@ -660,10 +746,11 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::Output_reloc(
     unsigned int shndx,
     Address address,
     bool is_relative,
-    bool is_symbolless)
+    bool is_symbolless,
+    bool use_plt_offset)
   : address_(address), local_sym_index_(GSYM_CODE), type_(type),
     is_relative_(is_relative), is_symbolless_(is_symbolless),
-    is_section_symbol_(false), shndx_(shndx)
+    is_section_symbol_(false), use_plt_offset_(use_plt_offset), shndx_(shndx)
 {
   gold_assert(shndx != INVALID_CODE);
   // this->type_ is a bitfield; make sure TYPE fits.
@@ -685,13 +772,15 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::Output_reloc(
     Address address,
     bool is_relative,
     bool is_symbolless,
-    bool is_section_symbol)
+    bool is_section_symbol,
+    bool use_plt_offset)
   : address_(address), local_sym_index_(local_sym_index), type_(type),
     is_relative_(is_relative), is_symbolless_(is_symbolless),
-    is_section_symbol_(is_section_symbol), shndx_(INVALID_CODE)
+    is_section_symbol_(is_section_symbol), use_plt_offset_(use_plt_offset),
+    shndx_(INVALID_CODE)
 {
   gold_assert(local_sym_index != GSYM_CODE
-              && local_sym_index != INVALID_CODE);
+             && local_sym_index != INVALID_CODE);
   // this->type_ is a bitfield; make sure TYPE fits.
   gold_assert(this->type_ == type);
   this->u1_.relobj = relobj;
@@ -709,13 +798,15 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::Output_reloc(
     Address address,
     bool is_relative,
     bool is_symbolless,
-    bool is_section_symbol)
+    bool is_section_symbol,
+    bool use_plt_offset)
   : address_(address), local_sym_index_(local_sym_index), type_(type),
     is_relative_(is_relative), is_symbolless_(is_symbolless),
-    is_section_symbol_(is_section_symbol), shndx_(shndx)
+    is_section_symbol_(is_section_symbol), use_plt_offset_(use_plt_offset),
+    shndx_(shndx)
 {
   gold_assert(local_sym_index != GSYM_CODE
-              && local_sym_index != INVALID_CODE);
+             && local_sym_index != INVALID_CODE);
   gold_assert(shndx != INVALID_CODE);
   // this->type_ is a bitfield; make sure TYPE fits.
   gold_assert(this->type_ == type);
@@ -732,10 +823,11 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::Output_reloc(
     Output_section* os,
     unsigned int type,
     Output_data* od,
-    Address address)
+    Address address,
+    bool is_relative)
   : address_(address), local_sym_index_(SECTION_CODE), type_(type),
-    is_relative_(false), is_symbolless_(false),
-    is_section_symbol_(true), shndx_(INVALID_CODE)
+    is_relative_(is_relative), is_symbolless_(is_relative),
+    is_section_symbol_(true), use_plt_offset_(false), shndx_(INVALID_CODE)
 {
   // this->type_ is a bitfield; make sure TYPE fits.
   gold_assert(this->type_ == type);
@@ -753,10 +845,11 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::Output_reloc(
     unsigned int type,
     Sized_relobj<size, big_endian>* relobj,
     unsigned int shndx,
-    Address address)
+    Address address,
+    bool is_relative)
   : address_(address), local_sym_index_(SECTION_CODE), type_(type),
-    is_relative_(false), is_symbolless_(false),
-    is_section_symbol_(true), shndx_(shndx)
+    is_relative_(is_relative), is_symbolless_(is_relative),
+    is_section_symbol_(true), use_plt_offset_(false), shndx_(shndx)
 {
   gold_assert(shndx != INVALID_CODE);
   // this->type_ is a bitfield; make sure TYPE fits.
@@ -769,16 +862,17 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::Output_reloc(
     os->set_needs_symtab_index();
 }
 
-// An absolute relocation.
+// An absolute or relative relocation.
 
 template<bool dynamic, int size, bool big_endian>
 Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::Output_reloc(
     unsigned int type,
     Output_data* od,
-    Address address)
+    Address address,
+    bool is_relative)
   : address_(address), local_sym_index_(0), type_(type),
-    is_relative_(false), is_symbolless_(false),
-    is_section_symbol_(false), shndx_(INVALID_CODE)
+    is_relative_(is_relative), is_symbolless_(false),
+    is_section_symbol_(false), use_plt_offset_(false), shndx_(INVALID_CODE)
 {
   // this->type_ is a bitfield; make sure TYPE fits.
   gold_assert(this->type_ == type);
@@ -791,10 +885,11 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::Output_reloc(
     unsigned int type,
     Sized_relobj<size, big_endian>* relobj,
     unsigned int shndx,
-    Address address)
+    Address address,
+    bool is_relative)
   : address_(address), local_sym_index_(0), type_(type),
-    is_relative_(false), is_symbolless_(false),
-    is_section_symbol_(false), shndx_(shndx)
+    is_relative_(is_relative), is_symbolless_(false),
+    is_section_symbol_(false), use_plt_offset_(false), shndx_(shndx)
 {
   gold_assert(shndx != INVALID_CODE);
   // this->type_ is a bitfield; make sure TYPE fits.
@@ -813,7 +908,7 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::Output_reloc(
     Address address)
   : address_(address), local_sym_index_(TARGET_CODE), type_(type),
     is_relative_(false), is_symbolless_(false),
-    is_section_symbol_(false), shndx_(INVALID_CODE)
+    is_section_symbol_(false), use_plt_offset_(false), shndx_(INVALID_CODE)
 {
   // this->type_ is a bitfield; make sure TYPE fits.
   gold_assert(this->type_ == type);
@@ -830,7 +925,7 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::Output_reloc(
     Address address)
   : address_(address), local_sym_index_(TARGET_CODE), type_(type),
     is_relative_(false), is_symbolless_(false),
-    is_section_symbol_(false), shndx_(shndx)
+    is_section_symbol_(false), use_plt_offset_(false), shndx_(shndx)
 {
   gold_assert(shndx != INVALID_CODE);
   // this->type_ is a bitfield; make sure TYPE fits.
@@ -870,11 +965,14 @@ set_needs_dynsym_index()
 
     default:
       {
-        const unsigned int lsi = this->local_sym_index_;
-        if (!this->is_section_symbol_)
-          this->u1_.relobj->set_needs_output_dynsym_entry(lsi);
-        else
-          this->u1_.relobj->output_section(lsi)->set_needs_dynsym_index();
+       const unsigned int lsi = this->local_sym_index_;
+       Sized_relobj_file<size, big_endian>* relobj =
+           this->u1_.relobj->sized_relobj();
+       gold_assert(relobj != NULL);
+       if (!this->is_section_symbol_)
+         relobj->set_needs_output_dynsym_entry(lsi);
+       else
+         relobj->output_section(lsi)->set_needs_dynsym_index();
       }
       break;
     }
@@ -923,23 +1021,26 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::get_symbol_index()
 
     default:
       {
-        const unsigned int lsi = this->local_sym_index_;
-        if (!this->is_section_symbol_)
-          {
-            if (dynamic)
-              index = this->u1_.relobj->dynsym_index(lsi);
-            else
-              index = this->u1_.relobj->symtab_index(lsi);
-          }
-        else
-          {
-            Output_section* os = this->u1_.relobj->output_section(lsi);
-            gold_assert(os != NULL);
-            if (dynamic)
-              index = os->dynsym_index();
-            else
-              index = os->symtab_index();
-          }
+       const unsigned int lsi = this->local_sym_index_;
+       Sized_relobj_file<size, big_endian>* relobj =
+           this->u1_.relobj->sized_relobj();
+       gold_assert(relobj != NULL);
+       if (!this->is_section_symbol_)
+         {
+           if (dynamic)
+             index = relobj->dynsym_index(lsi);
+           else
+             index = relobj->symtab_index(lsi);
+         }
+       else
+         {
+           Output_section* os = relobj->output_section(lsi);
+           gold_assert(os != NULL);
+           if (dynamic)
+             index = os->dynsym_index();
+           else
+             index = os->symtab_index();
+         }
       }
       break;
     }
@@ -956,11 +1057,11 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::
   local_section_offset(Addend addend) const
 {
   gold_assert(this->local_sym_index_ != GSYM_CODE
-              && this->local_sym_index_ != SECTION_CODE
+             && this->local_sym_index_ != SECTION_CODE
              && this->local_sym_index_ != TARGET_CODE
-              && this->local_sym_index_ != INVALID_CODE
+             && this->local_sym_index_ != INVALID_CODE
              && this->local_sym_index_ != 0
-              && this->is_section_symbol_);
+             && this->is_section_symbol_);
   const unsigned int lsi = this->local_sym_index_;
   Output_section* os = this->u1_.relobj->output_section(lsi);
   gold_assert(os != NULL);
@@ -968,7 +1069,10 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::
   if (offset != invalid_address)
     return offset + addend;
   // This is a merge section.
-  offset = os->output_address(this->u1_.relobj, lsi, addend);
+  Sized_relobj_file<size, big_endian>* relobj =
+      this->u1_.relobj->sized_relobj();
+  gold_assert(relobj != NULL);
+  offset = os->output_address(relobj, lsi, addend);
   gold_assert(offset != invalid_address);
   return offset;
 }
@@ -989,8 +1093,10 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::get_address() const
        address += os->address() + off;
       else
        {
-         address = os->output_address(this->u2_.relobj, this->shndx_,
-                                      address);
+         Sized_relobj_file<size, big_endian>* relobj =
+             this->u2_.relobj->sized_relobj();
+         gold_assert(relobj != NULL);
+         address = os->output_address(relobj, this->shndx_, address);
          gold_assert(address != invalid_address);
        }
     }
@@ -1035,16 +1141,28 @@ Output_reloc<elfcpp::SHT_REL, dynamic, size, big_endian>::symbol_value(
     {
       const Sized_symbol<size>* sym;
       sym = static_cast<const Sized_symbol<size>*>(this->u1_.gsym);
-      return sym->value() + addend;
+      if (this->use_plt_offset_ && sym->has_plt_offset())
+       return parameters->target().plt_address_for_global(sym);
+      else
+       return sym->value() + addend;
     }
-  gold_assert(this->local_sym_index_ != SECTION_CODE
-             && this->local_sym_index_ != TARGET_CODE
-              && this->local_sym_index_ != INVALID_CODE
+  if (this->local_sym_index_ == SECTION_CODE)
+    {
+      gold_assert(!this->use_plt_offset_);
+      return this->u1_.os->address() + addend;
+    }
+  gold_assert(this->local_sym_index_ != TARGET_CODE
+             && this->local_sym_index_ != INVALID_CODE
              && this->local_sym_index_ != 0
-              && !this->is_section_symbol_);
+             && !this->is_section_symbol_);
   const unsigned int lsi = this->local_sym_index_;
-  const Symbol_value<size>* symval = this->u1_.relobj->local_symbol(lsi);
-  return symval->value(this->u1_.relobj, addend);
+  Sized_relobj_file<size, big_endian>* relobj =
+      this->u1_.relobj->sized_relobj();
+  gold_assert(relobj != NULL);
+  if (this->use_plt_offset_)
+    return parameters->target().plt_address_for_local(relobj, lsi);
+  const Symbol_value<size>* symval = relobj->local_symbol(lsi);
+  return symval->value(relobj, addend);
 }
 
 // Reloc comparison.  This function sorts the dynamic relocs for the
@@ -1133,12 +1251,32 @@ Output_data_reloc_base<sh_type, dynamic, size, big_endian>
     os->set_entsize(elfcpp::Elf_sizes<size>::rela_size);
   else
     gold_unreachable();
-  if (dynamic)
-    os->set_should_link_to_dynsym();
-  else
+
+  // A STT_GNU_IFUNC symbol may require a IRELATIVE reloc when doing a
+  // static link.  The backends will generate a dynamic reloc section
+  // to hold this.  In that case we don't want to link to the dynsym
+  // section, because there isn't one.
+  if (!dynamic)
     os->set_should_link_to_symtab();
+  else if (parameters->doing_static_link())
+    ;
+  else
+    os->set_should_link_to_dynsym();
 }
 
+// Standard relocation writer, which just calls Output_reloc::write().
+
+template<int sh_type, bool dynamic, int size, bool big_endian>
+struct Output_reloc_writer
+{
+  typedef Output_reloc<sh_type, dynamic, size, big_endian> Output_reloc_type;
+  typedef std::vector<Output_reloc_type> Relocs;
+
+  static void
+  write(typename Relocs::const_iterator p, unsigned char* pov)
+  { p->write(pov); }
+};
+
 // Write out relocation data.
 
 template<int sh_type, bool dynamic, int size, bool big_endian>
@@ -1146,32 +1284,8 @@ void
 Output_data_reloc_base<sh_type, dynamic, size, big_endian>::do_write(
     Output_file* of)
 {
-  const off_t off = this->offset();
-  const off_t oview_size = this->data_size();
-  unsigned char* const oview = of->get_output_view(off, oview_size);
-
-  if (this->sort_relocs())
-    {
-      gold_assert(dynamic);
-      std::sort(this->relocs_.begin(), this->relocs_.end(),
-               Sort_relocs_comparison());
-    }
-
-  unsigned char* pov = oview;
-  for (typename Relocs::const_iterator p = this->relocs_.begin();
-       p != this->relocs_.end();
-       ++p)
-    {
-      p->write(pov);
-      pov += reloc_size;
-    }
-
-  gold_assert(pov - oview == oview_size);
-
-  of->write_output_view(off, oview_size, oview);
-
-  // We no longer need the relocation entries.
-  this->relocs_.clear();
+  typedef Output_reloc_writer<sh_type, dynamic, size, big_endian> Writer;
+  this->do_write_generic<Writer>(of);
 }
 
 // Class Output_relocatable_relocs.
@@ -1188,7 +1302,7 @@ Output_relocatable_relocs<sh_type, size, big_endian>::set_final_data_size()
 
 template<int size, bool big_endian>
 Output_data_group<size, big_endian>::Output_data_group(
-    Sized_relobj<size, big_endian>* relobj,
+    Sized_relobj_file<size, big_endian>* relobj,
     section_size_type entry_count,
     elfcpp::Elf_Word flags,
     std::vector<unsigned int>* input_shndxes)
@@ -1248,9 +1362,11 @@ Output_data_group<size, big_endian>::do_write(Output_file* of)
 
 // Write out the entry.
 
-template<int size, bool big_endian>
+template<int got_size, bool big_endian>
 void
-Output_data_got<size, big_endian>::Got_entry::write(unsigned char* pov) const
+Output_data_got<got_size, big_endian>::Got_entry::write(
+    unsigned int got_indx,
+    unsigned char* pov) const
 {
   Valtype val = 0;
 
@@ -1262,12 +1378,43 @@ Output_data_got<size, big_endian>::Got_entry::write(unsigned char* pov) const
        // link-time value, which will be relocated dynamically by a
        // RELATIVE relocation.
        Symbol* gsym = this->u_.gsym;
-       Sized_symbol<size>* sgsym;
-       // This cast is a bit ugly.  We don't want to put a
-       // virtual method in Symbol, because we want Symbol to be
-       // as small as possible.
-       sgsym = static_cast<Sized_symbol<size>*>(gsym);
-       val = sgsym->value();
+       if (this->use_plt_or_tls_offset_ && gsym->has_plt_offset())
+         val = parameters->target().plt_address_for_global(gsym);
+       else
+         {
+           switch (parameters->size_and_endianness())
+             {
+#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
+             case Parameters::TARGET_32_LITTLE:
+             case Parameters::TARGET_32_BIG:
+               {
+                 // This cast is ugly.  We don't want to put a
+                 // virtual method in Symbol, because we want Symbol
+                 // to be as small as possible.
+                 Sized_symbol<32>::Value_type v;
+                 v = static_cast<Sized_symbol<32>*>(gsym)->value();
+                 val = convert_types<Valtype, Sized_symbol<32>::Value_type>(v);
+               }
+               break;
+#endif
+#if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
+             case Parameters::TARGET_64_LITTLE:
+             case Parameters::TARGET_64_BIG:
+               {
+                 Sized_symbol<64>::Value_type v;
+                 v = static_cast<Sized_symbol<64>*>(gsym)->value();
+                 val = convert_types<Valtype, Sized_symbol<64>::Value_type>(v);
+               }
+               break;
+#endif
+             default:
+               gold_unreachable();
+             }
+           if (this->use_plt_or_tls_offset_
+               && gsym->type() == elfcpp::STT_TLS)
+             val += parameters->target().tls_offset_for_global(gsym,
+                                                               got_indx);
+         }
       }
       break;
 
@@ -1275,16 +1422,33 @@ Output_data_got<size, big_endian>::Got_entry::write(unsigned char* pov) const
       val = this->u_.constant;
       break;
 
+    case RESERVED_CODE:
+      // If we're doing an incremental update, don't touch this GOT entry.
+      if (parameters->incremental_update())
+       return;
+      val = this->u_.constant;
+      break;
+
     default:
       {
-        const unsigned int lsi = this->local_sym_index_;
-        const Symbol_value<size>* symval = this->u_.object->local_symbol(lsi);
-        val = symval->value(this->u_.object, 0);
+       const Relobj* object = this->u_.object;
+       const unsigned int lsi = this->local_sym_index_;
+       bool is_tls = object->local_is_tls(lsi);
+       if (this->use_plt_or_tls_offset_ && !is_tls)
+         val = parameters->target().plt_address_for_local(object, lsi);
+       else
+         {
+           uint64_t lval = object->local_symbol_value(lsi, this->addend_);
+           val = convert_types<Valtype, uint64_t>(lval);
+           if (this->use_plt_or_tls_offset_ && is_tls)
+             val += parameters->target().tls_offset_for_local(object, lsi,
+                                                              got_indx);
+         }
       }
       break;
     }
 
-  elfcpp::Swap<size, big_endian>::writeval(pov, val);
+  elfcpp::Swap<got_size, big_endian>::writeval(pov, val);
 }
 
 // Output_data_got methods.
@@ -1293,257 +1457,296 @@ Output_data_got<size, big_endian>::Got_entry::write(unsigned char* pov) const
 // this is a new GOT entry, false if the symbol already had a GOT
 // entry.
 
-template<int size, bool big_endian>
+template<int got_size, bool big_endian>
 bool
-Output_data_got<size, big_endian>::add_global(
+Output_data_got<got_size, big_endian>::add_global(
     Symbol* gsym,
     unsigned int got_type)
 {
   if (gsym->has_got_offset(got_type))
     return false;
 
-  this->entries_.push_back(Got_entry(gsym));
-  this->set_got_size();
-  gsym->set_got_offset(got_type, this->last_got_offset());
+  unsigned int got_offset = this->add_got_entry(Got_entry(gsym, false));
+  gsym->set_got_offset(got_type, got_offset);
   return true;
 }
 
-// Add an entry for a global symbol to the GOT, and add a dynamic
-// relocation of type R_TYPE for the GOT entry.
-template<int size, bool big_endian>
-void
-Output_data_got<size, big_endian>::add_global_with_rel(
-    Symbol* gsym,
-    unsigned int got_type,
-    Rel_dyn* rel_dyn,
-    unsigned int r_type)
+// Like add_global, but use the PLT offset.
+
+template<int got_size, bool big_endian>
+bool
+Output_data_got<got_size, big_endian>::add_global_plt(Symbol* gsym,
+                                                     unsigned int got_type)
 {
   if (gsym->has_got_offset(got_type))
-    return;
+    return false;
 
-  this->entries_.push_back(Got_entry());
-  this->set_got_size();
-  unsigned int got_offset = this->last_got_offset();
+  unsigned int got_offset = this->add_got_entry(Got_entry(gsym, true));
   gsym->set_got_offset(got_type, got_offset);
-  rel_dyn->add_global(gsym, r_type, this, got_offset);
+  return true;
 }
 
-template<int size, bool big_endian>
+// Add an entry for a global symbol to the GOT, and add a dynamic
+// relocation of type R_TYPE for the GOT entry.
+
+template<int got_size, bool big_endian>
 void
-Output_data_got<size, big_endian>::add_global_with_rela(
+Output_data_got<got_size, big_endian>::add_global_with_rel(
     Symbol* gsym,
     unsigned int got_type,
-    Rela_dyn* rela_dyn,
+    Output_data_reloc_generic* rel_dyn,
     unsigned int r_type)
 {
   if (gsym->has_got_offset(got_type))
     return;
 
-  this->entries_.push_back(Got_entry());
-  this->set_got_size();
-  unsigned int got_offset = this->last_got_offset();
+  unsigned int got_offset = this->add_got_entry(Got_entry());
   gsym->set_got_offset(got_type, got_offset);
-  rela_dyn->add_global(gsym, r_type, this, got_offset, 0);
+  rel_dyn->add_global_generic(gsym, r_type, this, got_offset, 0);
 }
 
 // Add a pair of entries for a global symbol to the GOT, and add
 // dynamic relocations of type R_TYPE_1 and R_TYPE_2, respectively.
 // If R_TYPE_2 == 0, add the second entry with no relocation.
-template<int size, bool big_endian>
+template<int got_size, bool big_endian>
 void
-Output_data_got<size, big_endian>::add_global_pair_with_rel(
+Output_data_got<got_size, big_endian>::add_global_pair_with_rel(
     Symbol* gsym,
     unsigned int got_type,
-    Rel_dyn* rel_dyn,
+    Output_data_reloc_generic* rel_dyn,
     unsigned int r_type_1,
     unsigned int r_type_2)
 {
   if (gsym->has_got_offset(got_type))
     return;
 
-  this->entries_.push_back(Got_entry());
-  unsigned int got_offset = this->last_got_offset();
+  unsigned int got_offset = this->add_got_entry_pair(Got_entry(), Got_entry());
   gsym->set_got_offset(got_type, got_offset);
-  rel_dyn->add_global(gsym, r_type_1, this, got_offset);
+  rel_dyn->add_global_generic(gsym, r_type_1, this, got_offset, 0);
 
-  this->entries_.push_back(Got_entry());
   if (r_type_2 != 0)
-    {
-      got_offset = this->last_got_offset();
-      rel_dyn->add_global(gsym, r_type_2, this, got_offset);
-    }
-
-  this->set_got_size();
+    rel_dyn->add_global_generic(gsym, r_type_2, this,
+                               got_offset + got_size / 8, 0);
 }
 
-template<int size, bool big_endian>
-void
-Output_data_got<size, big_endian>::add_global_pair_with_rela(
-    Symbol* gsym,
-    unsigned int got_type,
-    Rela_dyn* rela_dyn,
-    unsigned int r_type_1,
-    unsigned int r_type_2)
+// Add an entry for a local symbol to the GOT.  This returns true if
+// this is a new GOT entry, false if the symbol already has a GOT
+// entry.
+
+template<int got_size, bool big_endian>
+bool
+Output_data_got<got_size, big_endian>::add_local(
+    Relobj* object,
+    unsigned int symndx,
+    unsigned int got_type)
 {
-  if (gsym->has_got_offset(got_type))
-    return;
+  if (object->local_has_got_offset(symndx, got_type))
+    return false;
 
-  this->entries_.push_back(Got_entry());
-  unsigned int got_offset = this->last_got_offset();
-  gsym->set_got_offset(got_type, got_offset);
-  rela_dyn->add_global(gsym, r_type_1, this, got_offset, 0);
+  unsigned int got_offset = this->add_got_entry(Got_entry(object, symndx,
+                                                         false));
+  object->set_local_got_offset(symndx, got_type, got_offset);
+  return true;
+}
 
-  this->entries_.push_back(Got_entry());
-  if (r_type_2 != 0)
-    {
-      got_offset = this->last_got_offset();
-      rela_dyn->add_global(gsym, r_type_2, this, got_offset, 0);
-    }
+// Add an entry for a local symbol plus ADDEND to the GOT.  This returns
+// true if this is a new GOT entry, false if the symbol already has a GOT
+// entry.
 
-  this->set_got_size();
+template<int got_size, bool big_endian>
+bool
+Output_data_got<got_size, big_endian>::add_local(
+    Relobj* object,
+    unsigned int symndx,
+    unsigned int got_type,
+    uint64_t addend)
+{
+  if (object->local_has_got_offset(symndx, got_type, addend))
+    return false;
+
+  unsigned int got_offset = this->add_got_entry(Got_entry(object, symndx,
+                                                         false, addend));
+  object->set_local_got_offset(symndx, got_type, got_offset, addend);
+  return true;
 }
 
-// Add an entry for a local symbol to the GOT.  This returns true if
-// this is a new GOT entry, false if the symbol already has a GOT
-// entry.
+// Like add_local, but use the PLT offset.
 
-template<int size, bool big_endian>
+template<int got_size, bool big_endian>
 bool
-Output_data_got<size, big_endian>::add_local(
-    Sized_relobj<size, big_endian>* object,
+Output_data_got<got_size, big_endian>::add_local_plt(
+    Relobj* object,
     unsigned int symndx,
     unsigned int got_type)
 {
   if (object->local_has_got_offset(symndx, got_type))
     return false;
 
-  this->entries_.push_back(Got_entry(object, symndx));
-  this->set_got_size();
-  object->set_local_got_offset(symndx, got_type, this->last_got_offset());
+  unsigned int got_offset = this->add_got_entry(Got_entry(object, symndx,
+                                                         true));
+  object->set_local_got_offset(symndx, got_type, got_offset);
   return true;
 }
 
 // Add an entry for a local symbol to the GOT, and add a dynamic
 // relocation of type R_TYPE for the GOT entry.
-template<int size, bool big_endian>
+
+template<int got_size, bool big_endian>
 void
-Output_data_got<size, big_endian>::add_local_with_rel(
-    Sized_relobj<size, big_endian>* object,
+Output_data_got<got_size, big_endian>::add_local_with_rel(
+    Relobj* object,
     unsigned int symndx,
     unsigned int got_type,
-    Rel_dyn* rel_dyn,
+    Output_data_reloc_generic* rel_dyn,
     unsigned int r_type)
 {
   if (object->local_has_got_offset(symndx, got_type))
     return;
 
-  this->entries_.push_back(Got_entry());
-  this->set_got_size();
-  unsigned int got_offset = this->last_got_offset();
+  unsigned int got_offset = this->add_got_entry(Got_entry());
   object->set_local_got_offset(symndx, got_type, got_offset);
-  rel_dyn->add_local(object, symndx, r_type, this, got_offset);
+  rel_dyn->add_local_generic(object, symndx, r_type, this, got_offset, 0);
 }
 
-template<int size, bool big_endian>
+// Add an entry for a local symbol plus ADDEND to the GOT, and add a dynamic
+// relocation of type R_TYPE for the GOT entry.
+
+template<int got_size, bool big_endian>
 void
-Output_data_got<size, big_endian>::add_local_with_rela(
-    Sized_relobj<size, big_endian>* object,
+Output_data_got<got_size, big_endian>::add_local_with_rel(
+    Relobj* object,
     unsigned int symndx,
     unsigned int got_type,
-    Rela_dyn* rela_dyn,
-    unsigned int r_type)
+    Output_data_reloc_generic* rel_dyn,
+    unsigned int r_type, uint64_t addend)
 {
-  if (object->local_has_got_offset(symndx, got_type))
+  if (object->local_has_got_offset(symndx, got_type, addend))
     return;
 
-  this->entries_.push_back(Got_entry());
-  this->set_got_size();
-  unsigned int got_offset = this->last_got_offset();
-  object->set_local_got_offset(symndx, got_type, got_offset);
-  rela_dyn->add_local(object, symndx, r_type, this, got_offset, 0);
+  unsigned int got_offset = this->add_got_entry(Got_entry());
+  object->set_local_got_offset(symndx, got_type, got_offset, addend);
+  rel_dyn->add_local_generic(object, symndx, r_type, this, got_offset,
+                             addend);
 }
 
 // Add a pair of entries for a local symbol to the GOT, and add
-// dynamic relocations of type R_TYPE_1 and R_TYPE_2, respectively.
-// If R_TYPE_2 == 0, add the second entry with no relocation.
-template<int size, bool big_endian>
+// a dynamic relocation of type R_TYPE using the section symbol of
+// the output section to which input section SHNDX maps, on the first.
+// The first got entry will have a value of zero, the second the
+// value of the local symbol.
+template<int got_size, bool big_endian>
 void
-Output_data_got<size, big_endian>::add_local_pair_with_rel(
-    Sized_relobj<size, big_endian>* object,
+Output_data_got<got_size, big_endian>::add_local_pair_with_rel(
+    Relobj* object,
     unsigned int symndx,
     unsigned int shndx,
     unsigned int got_type,
-    Rel_dyn* rel_dyn,
-    unsigned int r_type_1,
-    unsigned int r_type_2)
+    Output_data_reloc_generic* rel_dyn,
+    unsigned int r_type)
 {
   if (object->local_has_got_offset(symndx, got_type))
     return;
 
-  this->entries_.push_back(Got_entry());
-  unsigned int got_offset = this->last_got_offset();
+  unsigned int got_offset =
+      this->add_got_entry_pair(Got_entry(),
+                              Got_entry(object, symndx, false));
   object->set_local_got_offset(symndx, got_type, got_offset);
   Output_section* os = object->output_section(shndx);
-  rel_dyn->add_output_section(os, r_type_1, this, got_offset);
+  rel_dyn->add_output_section_generic(os, r_type, this, got_offset, 0);
+}
 
-  this->entries_.push_back(Got_entry(object, symndx));
-  if (r_type_2 != 0)
-    {
-      got_offset = this->last_got_offset();
-      rel_dyn->add_output_section(os, r_type_2, this, got_offset);
-    }
+// Add a pair of entries for a local symbol plus ADDEND to the GOT, and add
+// a dynamic relocation of type R_TYPE using the section symbol of
+// the output section to which input section SHNDX maps, on the first.
+// The first got entry will have a value of zero, the second the
+// value of the local symbol.
+template<int got_size, bool big_endian>
+void
+Output_data_got<got_size, big_endian>::add_local_pair_with_rel(
+    Relobj* object,
+    unsigned int symndx,
+    unsigned int shndx,
+    unsigned int got_type,
+    Output_data_reloc_generic* rel_dyn,
+    unsigned int r_type, uint64_t addend)
+{
+  if (object->local_has_got_offset(symndx, got_type, addend))
+    return;
 
-  this->set_got_size();
+  unsigned int got_offset =
+      this->add_got_entry_pair(Got_entry(),
+                              Got_entry(object, symndx, false, addend));
+  object->set_local_got_offset(symndx, got_type, got_offset, addend);
+  Output_section* os = object->output_section(shndx);
+  rel_dyn->add_output_section_generic(os, r_type, this, got_offset, addend);
 }
 
-template<int size, bool big_endian>
+// Add a pair of entries for a local symbol to the GOT, and add
+// a dynamic relocation of type R_TYPE using STN_UNDEF on the first.
+// The first got entry will have a value of zero, the second the
+// value of the local symbol offset by Target::tls_offset_for_local.
+template<int got_size, bool big_endian>
 void
-Output_data_got<size, big_endian>::add_local_pair_with_rela(
-    Sized_relobj<size, big_endian>* object,
+Output_data_got<got_size, big_endian>::add_local_tls_pair(
+    Relobj* object,
     unsigned int symndx,
-    unsigned int shndx,
     unsigned int got_type,
-    Rela_dyn* rela_dyn,
-    unsigned int r_type_1,
-    unsigned int r_type_2)
+    Output_data_reloc_generic* rel_dyn,
+    unsigned int r_type)
 {
   if (object->local_has_got_offset(symndx, got_type))
     return;
 
-  this->entries_.push_back(Got_entry());
-  unsigned int got_offset = this->last_got_offset();
+  unsigned int got_offset
+    = this->add_got_entry_pair(Got_entry(),
+                              Got_entry(object, symndx, true));
   object->set_local_got_offset(symndx, got_type, got_offset);
-  Output_section* os = object->output_section(shndx);
-  rela_dyn->add_output_section(os, r_type_1, this, got_offset, 0);
+  rel_dyn->add_local_generic(object, 0, r_type, this, got_offset, 0);
+}
 
-  this->entries_.push_back(Got_entry(object, symndx));
-  if (r_type_2 != 0)
-    {
-      got_offset = this->last_got_offset();
-      rela_dyn->add_output_section(os, r_type_2, this, got_offset, 0);
-    }
+// Reserve a slot in the GOT for a local symbol or the second slot of a pair.
 
-  this->set_got_size();
+template<int got_size, bool big_endian>
+void
+Output_data_got<got_size, big_endian>::reserve_local(
+    unsigned int i,
+    Relobj* object,
+    unsigned int sym_index,
+    unsigned int got_type)
+{
+  this->do_reserve_slot(i);
+  object->set_local_got_offset(sym_index, got_type, this->got_offset(i));
+}
+
+// Reserve a slot in the GOT for a global symbol.
+
+template<int got_size, bool big_endian>
+void
+Output_data_got<got_size, big_endian>::reserve_global(
+    unsigned int i,
+    Symbol* gsym,
+    unsigned int got_type)
+{
+  this->do_reserve_slot(i);
+  gsym->set_got_offset(got_type, this->got_offset(i));
 }
 
 // Write out the GOT.
 
-template<int size, bool big_endian>
+template<int got_size, bool big_endian>
 void
-Output_data_got<size, big_endian>::do_write(Output_file* of)
+Output_data_got<got_size, big_endian>::do_write(Output_file* of)
 {
-  const int add = size / 8;
+  const int add = got_size / 8;
 
   const off_t off = this->offset();
   const off_t oview_size = this->data_size();
   unsigned char* const oview = of->get_output_view(off, oview_size);
 
   unsigned char* pov = oview;
-  for (typename Got_entries::const_iterator p = this->entries_.begin();
-       p != this->entries_.end();
-       ++p)
+  for (unsigned int i = 0; i < this->entries_.size(); ++i)
     {
-      p->write(pov);
+      this->entries_[i].write(i, pov);
       pov += add;
     }
 
@@ -1555,6 +1758,78 @@ Output_data_got<size, big_endian>::do_write(Output_file* of)
   this->entries_.clear();
 }
 
+// Create a new GOT entry and return its offset.
+
+template<int got_size, bool big_endian>
+unsigned int
+Output_data_got<got_size, big_endian>::add_got_entry(Got_entry got_entry)
+{
+  if (!this->is_data_size_valid())
+    {
+      this->entries_.push_back(got_entry);
+      this->set_got_size();
+      return this->last_got_offset();
+    }
+  else
+    {
+      // For an incremental update, find an available slot.
+      off_t got_offset = this->free_list_.allocate(got_size / 8,
+                                                  got_size / 8, 0);
+      if (got_offset == -1)
+       gold_fallback(_("out of patch space (GOT);"
+                       " relink with --incremental-full"));
+      unsigned int got_index = got_offset / (got_size / 8);
+      gold_assert(got_index < this->entries_.size());
+      this->entries_[got_index] = got_entry;
+      return static_cast<unsigned int>(got_offset);
+    }
+}
+
+// Create a pair of new GOT entries and return the offset of the first.
+
+template<int got_size, bool big_endian>
+unsigned int
+Output_data_got<got_size, big_endian>::add_got_entry_pair(
+    Got_entry got_entry_1,
+    Got_entry got_entry_2)
+{
+  if (!this->is_data_size_valid())
+    {
+      unsigned int got_offset;
+      this->entries_.push_back(got_entry_1);
+      got_offset = this->last_got_offset();
+      this->entries_.push_back(got_entry_2);
+      this->set_got_size();
+      return got_offset;
+    }
+  else
+    {
+      // For an incremental update, find an available pair of slots.
+      off_t got_offset = this->free_list_.allocate(2 * got_size / 8,
+                                                  got_size / 8, 0);
+      if (got_offset == -1)
+       gold_fallback(_("out of patch space (GOT);"
+                       " relink with --incremental-full"));
+      unsigned int got_index = got_offset / (got_size / 8);
+      gold_assert(got_index < this->entries_.size());
+      this->entries_[got_index] = got_entry_1;
+      this->entries_[got_index + 1] = got_entry_2;
+      return static_cast<unsigned int>(got_offset);
+    }
+}
+
+// Replace GOT entry I with a new value.
+
+template<int got_size, bool big_endian>
+void
+Output_data_got<got_size, big_endian>::replace_got_entry(
+    unsigned int i,
+    Got_entry got_entry)
+{
+  gold_assert(i < this->entries_.size());
+  this->entries_[i] = got_entry;
+}
+
 // Output_data_dynamic::Dynamic_entry methods.
 
 // Write out the entry.
@@ -1590,6 +1865,10 @@ Output_data_dynamic::Dynamic_entry::write(
       val = pool->get_offset(this->u_.str);
       break;
 
+    case DYNAMIC_CUSTOM:
+      val = parameters->target().dynamic_tag_custom_value(this->tag_);
+      break;
+
     default:
       val = this->u_.od->address() + this->offset_;
       break;
@@ -1615,6 +1894,27 @@ Output_data_dynamic::do_adjust_output_section(Output_section* os)
     gold_unreachable();
 }
 
+// Get a dynamic entry offset.
+
+unsigned int
+Output_data_dynamic::get_entry_offset(elfcpp::DT tag) const
+{
+  int dyn_size;
+
+  if (parameters->target().get_size() == 32)
+    dyn_size = elfcpp::Elf_sizes<32>::dyn_size;
+  else if (parameters->target().get_size() == 64)
+    dyn_size = elfcpp::Elf_sizes<64>::dyn_size;
+  else
+    gold_unreachable();
+
+  for (size_t i = 0; i < entries_.size(); ++i)
+    if (entries_[i].tag() == tag)
+      return i * dyn_size;
+
+  return -1U;
+}
+
 // Set the final data size.
 
 void
@@ -1730,13 +2030,164 @@ Output_symtab_xindex::endian_do_write(unsigned char* const oview)
        ++p)
     {
       unsigned int symndx = p->first;
-      gold_assert(symndx * 4 < this->data_size());
+      gold_assert(static_cast<off_t>(symndx) * 4 < this->data_size());
       elfcpp::Swap<32, big_endian>::writeval(oview + symndx * 4, p->second);
     }
 }
 
+// Output_fill_debug_info methods.
+
+// Return the minimum size needed for a dummy compilation unit header.
+
+size_t
+Output_fill_debug_info::do_minimum_hole_size() const
+{
+  // Compile unit header fields: unit_length, version, debug_abbrev_offset,
+  // address_size.
+  const size_t len = 4 + 2 + 4 + 1;
+  // For type units, add type_signature, type_offset.
+  if (this->is_debug_types_)
+    return len + 8 + 4;
+  return len;
+}
+
+// Write a dummy compilation unit header to fill a hole in the
+// .debug_info or .debug_types section.
+
+void
+Output_fill_debug_info::do_write(Output_file* of, off_t off, size_t len) const
+{
+  gold_debug(DEBUG_INCREMENTAL, "fill_debug_info(%08lx, %08lx)",
+            static_cast<long>(off), static_cast<long>(len));
+
+  gold_assert(len >= this->do_minimum_hole_size());
+
+  unsigned char* const oview = of->get_output_view(off, len);
+  unsigned char* pov = oview;
+
+  // Write header fields: unit_length, version, debug_abbrev_offset,
+  // address_size.
+  if (this->is_big_endian())
+    {
+      elfcpp::Swap_unaligned<32, true>::writeval(pov, len - 4);
+      elfcpp::Swap_unaligned<16, true>::writeval(pov + 4, this->version);
+      elfcpp::Swap_unaligned<32, true>::writeval(pov + 6, 0);
+    }
+  else
+    {
+      elfcpp::Swap_unaligned<32, false>::writeval(pov, len - 4);
+      elfcpp::Swap_unaligned<16, false>::writeval(pov + 4, this->version);
+      elfcpp::Swap_unaligned<32, false>::writeval(pov + 6, 0);
+    }
+  pov += 4 + 2 + 4;
+  *pov++ = 4;
+
+  // For type units, the additional header fields -- type_signature,
+  // type_offset -- can be filled with zeroes.
+
+  // Fill the remainder of the free space with zeroes.  The first
+  // zero should tell the consumer there are no DIEs to read in this
+  // compilation unit.
+  if (pov < oview + len)
+    memset(pov, 0, oview + len - pov);
+
+  of->write_output_view(off, len, oview);
+}
+
+// Output_fill_debug_line methods.
+
+// Return the minimum size needed for a dummy line number program header.
+
+size_t
+Output_fill_debug_line::do_minimum_hole_size() const
+{
+  // Line number program header fields: unit_length, version, header_length,
+  // minimum_instruction_length, default_is_stmt, line_base, line_range,
+  // opcode_base, standard_opcode_lengths[], include_directories, filenames.
+  const size_t len = 4 + 2 + 4 + this->header_length;
+  return len;
+}
+
+// Write a dummy line number program header to fill a hole in the
+// .debug_line section.
+
+void
+Output_fill_debug_line::do_write(Output_file* of, off_t off, size_t len) const
+{
+  gold_debug(DEBUG_INCREMENTAL, "fill_debug_line(%08lx, %08lx)",
+            static_cast<long>(off), static_cast<long>(len));
+
+  gold_assert(len >= this->do_minimum_hole_size());
+
+  unsigned char* const oview = of->get_output_view(off, len);
+  unsigned char* pov = oview;
+
+  // Write header fields: unit_length, version, header_length,
+  // minimum_instruction_length, default_is_stmt, line_base, line_range,
+  // opcode_base, standard_opcode_lengths[], include_directories, filenames.
+  // We set the header_length field to cover the entire hole, so the
+  // line number program is empty.
+  if (this->is_big_endian())
+    {
+      elfcpp::Swap_unaligned<32, true>::writeval(pov, len - 4);
+      elfcpp::Swap_unaligned<16, true>::writeval(pov + 4, this->version);
+      elfcpp::Swap_unaligned<32, true>::writeval(pov + 6, len - (4 + 2 + 4));
+    }
+  else
+    {
+      elfcpp::Swap_unaligned<32, false>::writeval(pov, len - 4);
+      elfcpp::Swap_unaligned<16, false>::writeval(pov + 4, this->version);
+      elfcpp::Swap_unaligned<32, false>::writeval(pov + 6, len - (4 + 2 + 4));
+    }
+  pov += 4 + 2 + 4;
+  *pov++ = 1;  // minimum_instruction_length
+  *pov++ = 0;  // default_is_stmt
+  *pov++ = 0;  // line_base
+  *pov++ = 5;  // line_range
+  *pov++ = 13; // opcode_base
+  *pov++ = 0;  // standard_opcode_lengths[1]
+  *pov++ = 1;  // standard_opcode_lengths[2]
+  *pov++ = 1;  // standard_opcode_lengths[3]
+  *pov++ = 1;  // standard_opcode_lengths[4]
+  *pov++ = 1;  // standard_opcode_lengths[5]
+  *pov++ = 0;  // standard_opcode_lengths[6]
+  *pov++ = 0;  // standard_opcode_lengths[7]
+  *pov++ = 0;  // standard_opcode_lengths[8]
+  *pov++ = 1;  // standard_opcode_lengths[9]
+  *pov++ = 0;  // standard_opcode_lengths[10]
+  *pov++ = 0;  // standard_opcode_lengths[11]
+  *pov++ = 1;  // standard_opcode_lengths[12]
+  *pov++ = 0;  // include_directories (empty)
+  *pov++ = 0;  // filenames (empty)
+
+  // Some consumers don't check the header_length field, and simply
+  // start reading the line number program immediately following the
+  // header.  For those consumers, we fill the remainder of the free
+  // space with DW_LNS_set_basic_block opcodes.  These are effectively
+  // no-ops: the resulting line table program will not create any rows.
+  if (pov < oview + len)
+    memset(pov, elfcpp::DW_LNS_set_basic_block, oview + len - pov);
+
+  of->write_output_view(off, len, oview);
+}
+
 // Output_section::Input_section methods.
 
+// Return the current data size.  For an input section we store the size here.
+// For an Output_section_data, we have to ask it for the size.
+
+off_t
+Output_section::Input_section::current_data_size() const
+{
+  if (this->is_input_section())
+    return this->u1_.data_size;
+  else
+    {
+      this->u2_.posd->pre_finalize_data_size();
+      return this->u2_.posd->current_data_size();
+    }
+}
+
 // Return the data size.  For an input section we store the size here.
 // For an Output_section_data, we have to ask it for the size.
 
@@ -1827,7 +2278,7 @@ Output_section::Input_section::output_offset(
     const Relobj* object,
     unsigned int shndx,
     section_offset_type offset,
-    section_offset_type *poutput) const
+    section_offset_typepoutput) const
 {
   if (!this->is_input_section())
     return this->u2_.posd->output_offset(object, shndx, offset, poutput);
@@ -1840,18 +2291,6 @@ Output_section::Input_section::output_offset(
     }
 }
 
-// Return whether this is the merge section for the input section
-// SHNDX in OBJECT.
-
-inline bool
-Output_section::Input_section::is_merge_section_for(const Relobj* object,
-                                                   unsigned int shndx) const
-{
-  if (this->is_input_section())
-    return false;
-  return this->u2_.posd->is_merge_section_for(object, shndx);
-}
-
 // Write out the data.  We don't have to do anything for an input
 // section--they are handled via Object::relocate--but this is where
 // we write out the data for an Output_section_data.
@@ -1888,9 +2327,9 @@ Output_section::Input_section::print_to_mapfile(Mapfile* mapfile) const
 
     case RELAXED_INPUT_SECTION_CODE:
       {
-        Output_relaxed_input_section* relaxed_section =
+       Output_relaxed_input_section* relaxed_section =
          this->relaxed_input_section();
-        mapfile->print_input_section(relaxed_section->relobj(),
+       mapfile->print_input_section(relaxed_section->relobj(),
                                     relaxed_section->shndx());
       }
       break;
@@ -1946,9 +2385,18 @@ Output_section::Output_section(const char* name, elfcpp::Elf_Word type,
     section_offsets_need_adjustment_(false),
     is_noload_(false),
     always_keeps_input_sections_(false),
+    has_fixed_layout_(false),
+    is_patch_space_allowed_(false),
+    is_unique_segment_(false),
     tls_offset_(0),
+    extra_segment_flags_(0),
+    segment_alignment_(0),
     checkpoint_(NULL),
-    lookup_maps_(new Output_section_lookup_maps)
+    lookup_maps_(new Output_section_lookup_maps),
+    free_list_(),
+    free_space_fill_(NULL),
+    patch_space_(0),
+    reloc_section_(NULL)
 {
   // An unallocated section has no address.  Forcing this means that
   // we don't need special treatment for symbols defined in debug
@@ -1993,14 +2441,20 @@ Output_section::set_entsize(uint64_t v)
 template<int size, bool big_endian>
 off_t
 Output_section::add_input_section(Layout* layout,
-                                 Sized_relobj<size, big_endian>* object,
+                                 Sized_relobj_file<size, big_endian>* object,
                                  unsigned int shndx,
                                  const char* secname,
                                  const elfcpp::Shdr<size, big_endian>& shdr,
                                  unsigned int reloc_shndx,
                                  bool have_sections_script)
 {
+  section_size_type input_section_size = shdr.get_sh_size();
+  section_size_type uncompressed_size;
   elfcpp::Elf_Xword addralign = shdr.get_sh_addralign();
+  if (object->section_is_compressed(shndx, &uncompressed_size,
+                                   &addralign))
+    input_section_size = uncompressed_size;
+
   if ((addralign & (addralign - 1)) != 0)
     {
       object->error(_("invalid alignment %lu for section \"%s\""),
@@ -2029,9 +2483,11 @@ Output_section::add_input_section(Layout* layout,
   // a Output_data_merge.  We don't try to handle relocations for such
   // a section.  We don't try to handle empty merge sections--they
   // mess up the mappings, and are useless anyhow.
+  // FIXME: Need to handle merge sections during incremental update.
   if ((sh_flags & elfcpp::SHF_MERGE) != 0
       && reloc_shndx == 0
-      && shdr.get_sh_size() > 0)
+      && shdr.get_sh_size() > 0
+      && !parameters->incremental())
     {
       // Keep information about merged input sections for rebuilding fast
       // lookup maps if we have sections-script or we do relaxation.
@@ -2048,18 +2504,36 @@ Output_section::add_input_section(Layout* layout,
        }
     }
 
-  off_t offset_in_section = this->current_data_size_for_child();
+  off_t offset_in_section;
+
+  if (this->has_fixed_layout())
+    {
+      // For incremental updates, find a chunk of unused space in the section.
+      offset_in_section = this->free_list_.allocate(input_section_size,
+                                                   addralign, 0);
+      if (offset_in_section == -1)
+       gold_fallback(_("out of patch space in section %s; "
+                       "relink with --incremental-full"),
+                     this->name());
+      return offset_in_section;
+    }
+
+  offset_in_section = this->current_data_size_for_child();
   off_t aligned_offset_in_section = align_address(offset_in_section,
-                                                  addralign);
+                                                 addralign);
+  this->set_current_data_size_for_child(aligned_offset_in_section
+                                       + input_section_size);
 
   // Determine if we want to delay code-fill generation until the output
   // section is written.  When the target is relaxing, we want to delay fill
-  // generating to avoid adjusting them during relaxation.
+  // generating to avoid adjusting them during relaxation.  Also, if we are
+  // sorting input sections we must delay fill generation.
   if (!this->generate_code_fills_at_write_
       && !have_sections_script
       && (sh_flags & elfcpp::SHF_EXECINSTR) != 0
       && parameters->target().has_code_fill()
-      && parameters->target().may_relax())
+      && (parameters->target().may_relax()
+         || layout->is_section_ordering_specified()))
     {
       gold_assert(this->fills_.empty());
       this->generate_code_fills_at_write_ = true;
@@ -2076,23 +2550,15 @@ Output_section::add_input_section(Layout* layout,
       // sections without input sections.
       off_t fill_len = aligned_offset_in_section - offset_in_section;
       if (this->input_sections_.empty())
-        this->fills_.push_back(Fill(offset_in_section, fill_len));
+       this->fills_.push_back(Fill(offset_in_section, fill_len));
       else
-        {
-          std::string fill_data(parameters->target().code_fill(fill_len));
-          Output_data_const* odc = new Output_data_const(fill_data, 1);
-          this->input_sections_.push_back(Input_section(odc));
-        }
+       {
+         std::string fill_data(parameters->target().code_fill(fill_len));
+         Output_data_const* odc = new Output_data_const(fill_data, 1);
+         this->input_sections_.push_back(Input_section(odc));
+       }
     }
 
-  section_size_type input_section_size = shdr.get_sh_size();
-  section_size_type uncompressed_size;
-  if (object->section_is_compressed(shndx, &uncompressed_size))
-    input_section_size = uncompressed_size;
-
-  this->set_current_data_size_for_child(aligned_offset_in_section
-                                       + input_section_size);
-
   // We need to keep track of this section if we are already keeping
   // track of sections, or if we are relaxing.  Also, if this is a
   // section which requires sorting, or which may require sorting in
@@ -2106,19 +2572,22 @@ Output_section::add_input_section(Layout* layout,
       || this->must_sort_attached_input_sections()
       || parameters->options().user_set_Map()
       || parameters->target().may_relax()
-      || parameters->options().section_ordering_file())
+      || layout->is_section_ordering_specified())
     {
-      Input_section isecn(object, shndx, shdr.get_sh_size(), addralign);
+      Input_section isecn(object, shndx, input_section_size, addralign);
+      /* If section ordering is requested by specifying a ordering file,
+        using --section-ordering-file, match the section name with
+        a pattern.  */
       if (parameters->options().section_ordering_file())
-        {
-          unsigned int section_order_index =
-            layout->find_section_order_index(std::string(secname));
+       {
+         unsigned int section_order_index =
+           layout->find_section_order_index(std::string(secname));
          if (section_order_index != 0)
-            {
-              isecn.set_section_order_index(section_order_index);
-              this->set_input_section_order_specified();
-            }
-        }
+           {
+             isecn.set_section_order_index(section_order_index);
+             this->set_input_section_order_specified();
+           }
+       }
       this->input_sections_.push_back(isecn);
     }
 
@@ -2135,20 +2604,66 @@ Output_section::add_output_section_data(Output_section_data* posd)
 
   if (posd->is_data_size_valid())
     {
-      off_t offset_in_section = this->current_data_size_for_child();
-      off_t aligned_offset_in_section = align_address(offset_in_section,
-                                                     posd->addralign());
-      this->set_current_data_size_for_child(aligned_offset_in_section
-                                           + posd->data_size());
+      off_t offset_in_section;
+      if (this->has_fixed_layout())
+       {
+         // For incremental updates, find a chunk of unused space.
+         offset_in_section = this->free_list_.allocate(posd->data_size(),
+                                                       posd->addralign(), 0);
+         if (offset_in_section == -1)
+           gold_fallback(_("out of patch space in section %s; "
+                           "relink with --incremental-full"),
+                         this->name());
+         // Finalize the address and offset now.
+         uint64_t addr = this->address();
+         off_t offset = this->offset();
+         posd->set_address_and_file_offset(addr + offset_in_section,
+                                           offset + offset_in_section);
+       }
+      else
+       {
+         offset_in_section = this->current_data_size_for_child();
+         off_t aligned_offset_in_section = align_address(offset_in_section,
+                                                         posd->addralign());
+         this->set_current_data_size_for_child(aligned_offset_in_section
+                                               + posd->data_size());
+       }
+    }
+  else if (this->has_fixed_layout())
+    {
+      // For incremental updates, arrange for the data to have a fixed layout.
+      // This will mean that additions to the data must be allocated from
+      // free space within the containing output section.
+      uint64_t addr = this->address();
+      posd->set_address(addr);
+      posd->set_file_offset(0);
+      // FIXME: This should eventually be unreachable.
+      // gold_unreachable();
     }
 }
 
 // Add a relaxed input section.
 
 void
-Output_section::add_relaxed_input_section(Output_relaxed_input_section* poris)
+Output_section::add_relaxed_input_section(Layout* layout,
+                                         Output_relaxed_input_section* poris,
+                                         const std::string& name)
 {
   Input_section inp(poris);
+
+  // If the --section-ordering-file option is used to specify the order of
+  // sections, we need to keep track of sections.
+  if (layout->is_section_ordering_specified())
+    {
+      unsigned int section_order_index =
+       layout->find_section_order_index(name);
+      if (section_order_index != 0)
+       {
+         inp.set_section_order_index(section_order_index);
+         this->set_input_section_order_specified();
+       }
+    }
+
   this->add_output_section_data(&inp);
   if (this->lookup_maps_->is_valid())
     this->lookup_maps_->add_relaxed_input_section(poris->relobj(),
@@ -2156,9 +2671,9 @@ Output_section::add_relaxed_input_section(Output_relaxed_input_section* poris)
 
   // For a relaxed section, we use the current data size.  Linker scripts
   // get all the input sections, including relaxed one from an output
-  // section and add them back to them same output section to compute the
+  // section and add them back to the same output section to compute the
   // output section size.  If we do not account for sizes of relaxed input
-  // sections,  an output section would be incorrectly sized.
+  // sections, an output section would be incorrectly sized.
   off_t offset_in_section = this->current_data_size_for_child();
   off_t aligned_offset_in_section = align_address(offset_in_section,
                                                  poris->addralign());
@@ -2201,13 +2716,12 @@ Output_section::add_merge_input_section(Relobj* object, unsigned int shndx,
                                        uint64_t addralign,
                                        bool keeps_input_sections)
 {
-  bool is_string = (flags & elfcpp::SHF_STRINGS) != 0;
-
-  // We only merge strings if the alignment is not more than the
-  // character size.  This could be handled, but it's unusual.
-  if (is_string && addralign > entsize)
+  // We cannot merge sections with entsize == 0.
+  if (entsize == 0)
     return false;
 
+  bool is_string = (flags & elfcpp::SHF_STRINGS) != 0;
+
   // We cannot restore merged input section states.
   gold_assert(this->checkpoint_ == NULL);
 
@@ -2264,9 +2778,6 @@ Output_section::add_merge_input_section(Relobj* object, unsigned int shndx,
          this->lookup_maps_->add_merge_section(msp, pomb);
        }
 
-      // Add input section to new merge section and link input section to new
-      // merge section in map.
-      this->lookup_maps_->add_merge_input_section(object, shndx, pomb);
       return true;
     }
   else
@@ -2316,10 +2827,16 @@ Output_section::convert_input_sections_in_list_to_relaxed_sections(
       Relaxation_map::const_iterator p = map.find(sid);
       gold_assert(p != map.end());
       gold_assert((*input_sections)[p->second].is_input_section());
+
+      // Remember section order index of original input section
+      // if it is set.  Copy it to the relaxed input section.
+      unsigned int soi =
+       (*input_sections)[p->second].section_order_index();
       (*input_sections)[p->second] = Input_section(poris);
+      (*input_sections)[p->second].set_section_order_index(soi);
     }
 }
-  
+
 // Convert regular input sections into relaxed input sections. RELAXED_SECTIONS
 // is a vector of pointers to Output_relaxed_input_section or its derived
 // classes.  The relaxed sections must correspond to existing input sections.
@@ -2334,7 +2851,7 @@ Output_section::convert_input_sections_to_relaxed_sections(
   // this.  If there is no checkpoint active, just search the current
   // input section list and replace the sections there.  If there is
   // a checkpoint, also replace the sections there.
-  
+
   // By default, we look at the whole list.
   size_t limit = this->input_sections_.size();
 
@@ -2417,17 +2934,15 @@ Output_section::update_flags_for_input_section(elfcpp::Elf_Xword flags)
 // Find the merge section into which an input section with index SHNDX in
 // OBJECT has been added.  Return NULL if none found.
 
-Output_section_data*
+const Output_section_data*
 Output_section::find_merge_section(const Relobj* object,
                                   unsigned int shndx) const
 {
-  if (!this->lookup_maps_->is_valid())
-    this->build_lookup_maps();
-  return this->lookup_maps_->find_merge_section(object, shndx);
+  return object->find_merge_section(shndx);
 }
 
-// Build the lookup maps for merge and relaxed sections.  This is needs
-// to be declared as a const methods so that it is callable with a const
+// Build the lookup maps for relaxed sections.  This needs
+// to be declared as a const method so that it is callable with a const
 // Output_section pointer.  The method only updates states of the maps.
 
 void
@@ -2438,24 +2953,7 @@ Output_section::build_lookup_maps() const
        p != this->input_sections_.end();
        ++p)
     {
-      if (p->is_merge_section())
-       {
-         Output_merge_base* pomb = p->output_merge_base();
-         Merge_section_properties msp(pomb->is_string(), pomb->entsize(),
-                                      pomb->addralign());
-         this->lookup_maps_->add_merge_section(msp, pomb);
-         for (Output_merge_base::Input_sections::const_iterator is =
-                pomb->input_sections_begin();
-              is != pomb->input_sections_end();
-              ++is) 
-           {
-             const Const_section_id& csid = *is;
-           this->lookup_maps_->add_merge_input_section(csid.first,
-                                                       csid.second, pomb);
-           }
-           
-       }
-      else if (p->is_relaxed_input_section())
+      if (p->is_relaxed_input_section())
        {
          Output_relaxed_input_section* poris = p->relaxed_input_section();
          this->lookup_maps_->add_relaxed_input_section(poris->relobj(),
@@ -2495,7 +2993,10 @@ Output_section::is_input_address_mapped(const Relobj* object,
     {
       section_offset_type output_offset;
       bool found = posd->output_offset(object, shndx, offset, &output_offset);
-      gold_assert(found);   
+      // By default we assume that the address is mapped. See comment at the
+      // end.
+      if (!found)
+        return true;
       return output_offset != -1;
     }
 
@@ -2530,13 +3031,13 @@ Output_section::output_offset(const Relobj* object, unsigned int shndx,
 
   // Look at the Output_section_data_maps first.
   const Output_section_data* posd = this->find_merge_section(object, shndx);
-  if (posd == NULL) 
+  if (posd == NULL)
     posd = this->find_relaxed_input_section(object, shndx);
   if (posd != NULL)
     {
       section_offset_type output_offset;
       bool found = posd->output_offset(object, shndx, offset, &output_offset);
-      gold_assert(found);   
+      gold_assert(found);
       return output_offset;
     }
 
@@ -2563,7 +3064,7 @@ Output_section::output_address(const Relobj* object, unsigned int shndx,
 
   // Look at the Output_section_data_maps first.
   const Output_section_data* posd = this->find_merge_section(object, shndx);
-  if (posd == NULL) 
+  if (posd == NULL)
     posd = this->find_relaxed_input_section(object, shndx);
   if (posd != NULL && posd->is_address_valid())
     {
@@ -2605,6 +3106,10 @@ Output_section::find_starting_output_address(const Relobj* object,
                                             unsigned int shndx,
                                             uint64_t* paddr) const
 {
+  const Output_section_data* data = this->find_merge_section(object, shndx);
+  if (data == NULL)
+    return false;
+
   // FIXME: This becomes a bottle-neck if we have many relaxed sections.
   // Looking up the merge section map does not always work as we sometimes
   // find a merge section without its address set.
@@ -2619,7 +3124,7 @@ Output_section::find_starting_output_address(const Relobj* object,
       // method to get the output offset of input offset 0.
       // Unfortunately we don't know for sure that input offset 0 is
       // mapped at all.
-      if (p->is_merge_section_for(object, shndx))
+      if (!p->is_input_section() && p->output_section_data() == data)
        {
          *paddr = addr;
          return true;
@@ -2632,36 +3137,81 @@ Output_section::find_starting_output_address(const Relobj* object,
   return false;
 }
 
+// Update the data size of an Output_section.
+
+void
+Output_section::update_data_size()
+{
+  if (this->input_sections_.empty())
+      return;
+
+  if (this->must_sort_attached_input_sections()
+      || this->input_section_order_specified())
+    this->sort_attached_input_sections();
+
+  off_t off = this->first_input_offset_;
+  for (Input_section_list::iterator p = this->input_sections_.begin();
+       p != this->input_sections_.end();
+       ++p)
+    {
+      off = align_address(off, p->addralign());
+      off += p->current_data_size();
+    }
+
+  this->set_current_data_size_for_child(off);
+}
+
 // Set the data size of an Output_section.  This is where we handle
 // setting the addresses of any Output_section_data objects.
 
 void
 Output_section::set_final_data_size()
 {
+  off_t data_size;
+
   if (this->input_sections_.empty())
+    data_size = this->current_data_size_for_child();
+  else
     {
-      this->set_data_size(this->current_data_size_for_child());
-      return;
-    }
+      if (this->must_sort_attached_input_sections()
+         || this->input_section_order_specified())
+       this->sort_attached_input_sections();
 
-  if (this->must_sort_attached_input_sections()
-      || this->input_section_order_specified())
-    this->sort_attached_input_sections();
+      uint64_t address = this->address();
+      off_t startoff = this->offset();
+      off_t off = this->first_input_offset_;
+      for (Input_section_list::iterator p = this->input_sections_.begin();
+          p != this->input_sections_.end();
+          ++p)
+       {
+         off = align_address(off, p->addralign());
+         p->set_address_and_file_offset(address + off, startoff + off,
+                                        startoff);
+         off += p->data_size();
+       }
+      data_size = off;
+    }
 
-  uint64_t address = this->address();
-  off_t startoff = this->offset();
-  off_t off = startoff + this->first_input_offset_;
-  for (Input_section_list::iterator p = this->input_sections_.begin();
-       p != this->input_sections_.end();
-       ++p)
+  // For full incremental links, we want to allocate some patch space
+  // in most sections for subsequent incremental updates.
+  if (this->is_patch_space_allowed_ && parameters->incremental_full())
     {
-      off = align_address(off, p->addralign());
-      p->set_address_and_file_offset(address + (off - startoff), off,
-                                    startoff);
-      off += p->data_size();
+      double pct = parameters->options().incremental_patch();
+      size_t extra = static_cast<size_t>(data_size * pct);
+      if (this->free_space_fill_ != NULL
+         && this->free_space_fill_->minimum_hole_size() > extra)
+       extra = this->free_space_fill_->minimum_hole_size();
+      off_t new_size = align_address(data_size + extra, this->addralign());
+      this->patch_space_ = new_size - data_size;
+      gold_debug(DEBUG_INCREMENTAL,
+                "set_final_data_size: %08lx + %08lx: section %s",
+                static_cast<long>(data_size),
+                static_cast<long>(this->patch_space_),
+                this->name());
+      data_size = new_size;
     }
 
-  this->set_data_size(off - startoff);
+  this->set_data_size(data_size);
 }
 
 // Reset the address and file offset.
@@ -2680,8 +3230,16 @@ Output_section::do_reset_address_and_file_offset()
        p != this->input_sections_.end();
        ++p)
     p->reset_address_and_file_offset();
+
+  // Remove any patch space that was added in set_final_data_size.
+  if (this->patch_space_ > 0)
+    {
+      this->set_current_data_size_for_child(this->current_data_size_for_child()
+                                           - this->patch_space_);
+      this->patch_space_ = 0;
+    }
 }
-  
+
 // Return true if address and file offset have the values after reset.
 
 bool
@@ -2710,26 +3268,25 @@ Output_section::do_set_tls_offset(uint64_t tls_base)
 // priority ordering implemented by the GNU linker, in which the
 // priority becomes part of the section name and the sections are
 // sorted by name.  We only do this for an output section if we see an
-// attached input section matching ".ctor.*", ".dtor.*",
+// attached input section matching ".ctors.*", ".dtors.*",
 // ".init_array.*" or ".fini_array.*".
 
 class Output_section::Input_section_sort_entry
 {
  public:
   Input_section_sort_entry()
-    : input_section_(), index_(-1U), section_has_name_(false),
-      section_name_()
+    : input_section_(), index_(-1U), section_name_()
   { }
 
   Input_section_sort_entry(const Input_section& input_section,
                           unsigned int index,
-                          bool must_sort_attached_input_sections)
-    : input_section_(input_section), index_(index),
-      section_has_name_(input_section.is_input_section()
-                       || input_section.is_relaxed_input_section())
+                          bool must_sort_attached_input_sections,
+                          const char* output_section_name)
+    : input_section_(input_section), index_(index), section_name_()
   {
-    if (this->section_has_name_
-        && must_sort_attached_input_sections)
+    if ((input_section.is_input_section()
+        || input_section.is_relaxed_input_section())
+       && must_sort_attached_input_sections)
       {
        // This is only called single-threaded from Layout::finalize,
        // so it is OK to lock.  Unfortunately we have no way to pass
@@ -2744,6 +3301,12 @@ class Output_section::Input_section_sort_entry
        // Layout::layout if this becomes a speed problem.
        this->section_name_ = obj->section_name(input_section.shndx());
       }
+    else if (input_section.is_output_section_data()
+            && must_sort_attached_input_sections)
+      {
+       // For linker-generated sections, use the output section name.
+       this->section_name_.assign(output_section_name);
+      }
   }
 
   // Return the Input_section.
@@ -2763,16 +3326,10 @@ class Output_section::Input_section_sort_entry
     return this->index_;
   }
 
-  // Whether there is a section name.
-  bool
-  section_has_name() const
-  { return this->section_has_name_; }
-
   // The section name.
   const std::string&
   section_name() const
   {
-    gold_assert(this->section_has_name_);
     return this->section_name_;
   }
 
@@ -2781,10 +3338,36 @@ class Output_section::Input_section_sort_entry
   bool
   has_priority() const
   {
-    gold_assert(this->section_has_name_);
     return this->section_name_.find('.', 1) != std::string::npos;
   }
 
+  // Return the priority.  Believe it or not, gcc encodes the priority
+  // differently for .ctors/.dtors and .init_array/.fini_array
+  // sections.
+  unsigned int
+  get_priority() const
+  {
+    bool is_ctors;
+    if (is_prefix_of(".ctors.", this->section_name_.c_str())
+       || is_prefix_of(".dtors.", this->section_name_.c_str()))
+      is_ctors = true;
+    else if (is_prefix_of(".init_array.", this->section_name_.c_str())
+            || is_prefix_of(".fini_array.", this->section_name_.c_str()))
+      is_ctors = false;
+    else
+      return 0;
+    char* end;
+    unsigned long prio = strtoul((this->section_name_.c_str()
+                                 + (is_ctors ? 7 : 12)),
+                                &end, 10);
+    if (*end != '\0')
+      return 0;
+    else if (is_ctors)
+      return 65535 - prio;
+    else
+      return prio;
+  }
+
   // Return true if this an input file whose base name matches
   // FILE_NAME.  The base name must have an extension of ".o", and
   // must be exactly FILE_NAME.o or FILE_NAME, one character, ".o".
@@ -2793,17 +3376,11 @@ class Output_section::Input_section_sort_entry
   // file name this way is a dreadful hack, but the GNU linker does it
   // in order to better support gcc, and we need to be compatible.
   bool
-  match_file_name(const char* match_file_name) const
+  match_file_name(const char* file_name) const
   {
-    const std::string& file_name(this->input_section_.relobj()->name());
-    const char* base_name = lbasename(file_name.c_str());
-    size_t match_len = strlen(match_file_name);
-    if (strncmp(base_name, match_file_name, match_len) != 0)
-      return false;
-    size_t base_len = strlen(base_name);
-    if (base_len != match_len + 2 && base_len != match_len + 3)
+    if (this->input_section_.is_output_section_data())
       return false;
-    return memcmp(base_name + base_len - 2, ".o", 2) == 0;
+    return Layout::match_file_name(this->input_section_.relobj(), file_name);
   }
 
   // Returns 1 if THIS should appear before S in section order, -1 if S
@@ -2815,10 +3392,10 @@ class Output_section::Input_section_sort_entry
     unsigned int s_secn_index = s.input_section().section_order_index();
     if (this_secn_index > 0 && s_secn_index > 0)
       {
-        if (this_secn_index < s_secn_index)
-          return 1;
-        else if (this_secn_index > s_secn_index)
-          return -1;
+       if (this_secn_index < s_secn_index)
+         return 1;
+       else if (this_secn_index > s_secn_index)
+         return -1;
       }
     return 0;
   }
@@ -2828,9 +3405,6 @@ class Output_section::Input_section_sort_entry
   Input_section input_section_;
   // The index of this Input_section in the original list.
   unsigned int index_;
-  // Whether this Input_section has a section name--it won't if this
-  // is some random Output_section_data.
-  bool section_has_name_;
   // The section name if there is one.
   std::string section_name_;
 };
@@ -2866,16 +3440,6 @@ Output_section::Input_section_sort_compare::operator()(
       return s1.index() < s2.index();
     }
 
-  // We sort all the sections with no names to the end.
-  if (!s1.section_has_name() || !s2.section_has_name())
-    {
-      if (s1.section_has_name())
-       return true;
-      if (s2.section_has_name())
-       return false;
-      return s1.index() < s2.index();
-    }
-
   // A section with a priority follows a section without a priority.
   bool s1_has_priority = s1.has_priority();
   bool s2_has_priority = s2.has_priority();
@@ -2907,16 +3471,6 @@ Output_section::Input_section_sort_init_fini_compare::operator()(
     const Output_section::Input_section_sort_entry& s1,
     const Output_section::Input_section_sort_entry& s2) const
 {
-  // We sort all the sections with no names to the end.
-  if (!s1.section_has_name() || !s2.section_has_name())
-    {
-      if (s1.section_has_name())
-       return true;
-      if (s2.section_has_name())
-       return false;
-      return s1.index() < s2.index();
-    }
-
   // A section without a priority follows a section with a priority.
   // This is the reverse of .ctors and .dtors sections.
   bool s1_has_priority = s1.has_priority();
@@ -2926,6 +3480,28 @@ Output_section::Input_section_sort_init_fini_compare::operator()(
   if (!s1_has_priority && s2_has_priority)
     return false;
 
+  // .ctors and .dtors sections without priority come after
+  // .init_array and .fini_array sections without priority.
+  if (!s1_has_priority
+      && (s1.section_name() == ".ctors" || s1.section_name() == ".dtors")
+      && s1.section_name() != s2.section_name())
+    return false;
+  if (!s2_has_priority
+      && (s2.section_name() == ".ctors" || s2.section_name() == ".dtors")
+      && s2.section_name() != s1.section_name())
+    return true;
+
+  // Sort by priority if we can.
+  if (s1_has_priority)
+    {
+      unsigned int s1_prio = s1.get_priority();
+      unsigned int s2_prio = s2.get_priority();
+      if (s1_prio < s2_prio)
+       return true;
+      else if (s1_prio > s2_prio)
+       return false;
+    }
+
   // Check if a section order exists for these sections through a section
   // ordering file.  If sequence_num is 0, an order does not exist.
   int sequence_num = s1.compare_section_ordering(s2);
@@ -2956,10 +3532,91 @@ Output_section::Input_section_sort_section_order_index_compare::operator()(
   // Keep input order if section ordering cannot determine order.
   if (s1_secn_index == s2_secn_index)
     return s1.index() < s2.index();
-  
+
   return s1_secn_index < s2_secn_index;
 }
 
+// Return true if S1 should come before S2.  This is the sort comparison
+// function for .text to sort sections with prefixes
+// .text.{unlikely,exit,startup,hot} before other sections.
+
+bool
+Output_section::Input_section_sort_section_prefix_special_ordering_compare
+  ::operator()(
+    const Output_section::Input_section_sort_entry& s1,
+    const Output_section::Input_section_sort_entry& s2) const
+{
+  // Some input section names have special ordering requirements.
+  const char *s1_section_name = s1.section_name().c_str();
+  const char *s2_section_name = s2.section_name().c_str();
+  int o1 = Layout::special_ordering_of_input_section(s1_section_name);
+  int o2 = Layout::special_ordering_of_input_section(s2_section_name);
+  if (o1 != o2)
+    {
+      if (o1 < 0)
+       return false;
+      else if (o2 < 0)
+       return true;
+      else
+       return o1 < o2;
+    }
+  else if (is_prefix_of(".text.sorted", s1_section_name))
+    return strcmp(s1_section_name, s2_section_name) <= 0;
+
+  // Keep input order otherwise.
+  return s1.index() < s2.index();
+}
+
+// Return true if S1 should come before S2.  This is the sort comparison
+// function for sections to sort them by name.
+
+bool
+Output_section::Input_section_sort_section_name_compare
+  ::operator()(
+    const Output_section::Input_section_sort_entry& s1,
+    const Output_section::Input_section_sort_entry& s2) const
+{
+  // We sort by name.
+  int compare = s1.section_name().compare(s2.section_name());
+  if (compare != 0)
+    return compare < 0;
+
+  // Keep input order otherwise.
+  return s1.index() < s2.index();
+}
+
+// This updates the section order index of input sections according to the
+// the order specified in the mapping from Section id to order index.
+
+void
+Output_section::update_section_layout(
+  const Section_layout_order* order_map)
+{
+  for (Input_section_list::iterator p = this->input_sections_.begin();
+       p != this->input_sections_.end();
+       ++p)
+    {
+      if (p->is_input_section()
+         || p->is_relaxed_input_section())
+       {
+         Relobj* obj = (p->is_input_section()
+                        ? p->relobj()
+                        : p->relaxed_input_section()->relobj());
+         unsigned int shndx = p->shndx();
+         Section_layout_order::const_iterator it
+           = order_map->find(Section_id(obj, shndx));
+         if (it == order_map->end())
+           continue;
+         unsigned int section_order_index = it->second;
+         if (section_order_index != 0)
+           {
+             p->set_section_order_index(section_order_index);
+             this->set_input_section_order_specified();
+           }
+       }
+    }
+}
+
 // Sort the input sections attached to an output section.
 
 void
@@ -2986,25 +3643,32 @@ Output_section::sort_attached_input_sections()
        p != this->input_sections_.end();
        ++p, ++i)
       sort_list.push_back(Input_section_sort_entry(*p, i,
-                            this->must_sort_attached_input_sections()));
+                           this->must_sort_attached_input_sections(),
+                           this->name()));
 
   // Sort the input sections.
   if (this->must_sort_attached_input_sections())
     {
       if (this->type() == elfcpp::SHT_PREINIT_ARRAY
-          || this->type() == elfcpp::SHT_INIT_ARRAY
-          || this->type() == elfcpp::SHT_FINI_ARRAY)
-        std::sort(sort_list.begin(), sort_list.end(),
-                 Input_section_sort_init_fini_compare());
+         || this->type() == elfcpp::SHT_INIT_ARRAY
+         || this->type() == elfcpp::SHT_FINI_ARRAY)
+       std::sort(sort_list.begin(), sort_list.end(),
+                 Input_section_sort_init_fini_compare());
+      else if (strcmp(parameters->options().sort_section(), "name") == 0)
+       std::sort(sort_list.begin(), sort_list.end(),
+                 Input_section_sort_section_name_compare());
+      else if (strcmp(this->name(), ".text") == 0)
+       std::sort(sort_list.begin(), sort_list.end(),
+                 Input_section_sort_section_prefix_special_ordering_compare());
       else
-        std::sort(sort_list.begin(), sort_list.end(),
-                 Input_section_sort_compare());
+       std::sort(sort_list.begin(), sort_list.end(),
+                 Input_section_sort_compare());
     }
   else
     {
-      gold_assert(parameters->options().section_ordering_file());
+      gold_assert(this->input_section_order_specified());
       std::sort(sort_list.begin(), sort_list.end(),
-               Input_section_sort_section_order_index_compare());
+               Input_section_sort_section_order_index_compare());
     }
 
   // Copy the sorted input sections back to our list.
@@ -3042,7 +3706,7 @@ Output_section::write_header(const Layout* layout,
   if (this->link_section_ != NULL)
     oshdr->put_sh_link(this->link_section_->out_shndx());
   else if (this->should_link_to_symtab_)
-    oshdr->put_sh_link(layout->symtab_section()->out_shndx());
+    oshdr->put_sh_link(layout->symtab_section_shndx());
   else if (this->should_link_to_dynsym_)
     oshdr->put_sh_link(layout->dynsym_section()->out_shndx());
   else
@@ -3104,6 +3768,26 @@ Output_section::do_write(Output_file* of)
       p->write(of);
       off = aligned_off + p->data_size();
     }
+
+  // For incremental links, fill in unused chunks in debug sections
+  // with dummy compilation unit headers.
+  if (this->free_space_fill_ != NULL)
+    {
+      for (Free_list::Const_iterator p = this->free_list_.begin();
+          p != this->free_list_.end();
+          ++p)
+       {
+         off_t off = p->start_;
+         size_t len = p->end_ - off;
+         this->free_space_fill_->write(of, this->offset() + off, len);
+       }
+      if (this->patch_space_ > 0)
+       {
+         off_t off = this->current_data_size_for_child() - this->patch_space_;
+         this->free_space_fill_->write(of, this->offset() + off,
+                                       this->patch_space_);
+       }
+    }
 }
 
 // If a section requires postprocessing, create the buffer to use.
@@ -3267,23 +3951,10 @@ Output_section::add_script_input_section(const Input_section& sis)
 
   this->input_sections_.push_back(sis);
 
-  // Update fast lookup maps if necessary. 
+  // Update fast lookup maps if necessary.
   if (this->lookup_maps_->is_valid())
     {
-      if (sis.is_merge_section())
-       {
-         Output_merge_base* pomb = sis.output_merge_base();
-         Merge_section_properties msp(pomb->is_string(), pomb->entsize(),
-                                      pomb->addralign());
-         this->lookup_maps_->add_merge_section(msp, pomb);
-         for (Output_merge_base::Input_sections::const_iterator p =
-                pomb->input_sections_begin();
-              p != pomb->input_sections_end();
-              ++p)
-           this->lookup_maps_->add_merge_input_section(p->first, p->second,
-                                                       pomb);
-       }
-      else if (sis.is_relaxed_input_section())
+      if (sis.is_relaxed_input_section())
        {
          Output_relaxed_input_section* poris = sis.relaxed_input_section();
          this->lookup_maps_->add_relaxed_input_section(poris->relobj(),
@@ -3402,6 +4073,40 @@ Output_section::print_merge_stats()
     p->print_merge_stats(this->name_);
 }
 
+// Set a fixed layout for the section.  Used for incremental update links.
+
+void
+Output_section::set_fixed_layout(uint64_t sh_addr, off_t sh_offset,
+                                off_t sh_size, uint64_t sh_addralign)
+{
+  this->addralign_ = sh_addralign;
+  this->set_current_data_size(sh_size);
+  if ((this->flags_ & elfcpp::SHF_ALLOC) != 0)
+    this->set_address(sh_addr);
+  this->set_file_offset(sh_offset);
+  this->finalize_data_size();
+  this->free_list_.init(sh_size, false);
+  this->has_fixed_layout_ = true;
+}
+
+// Reserve space within the fixed layout for the section.  Used for
+// incremental update links.
+
+void
+Output_section::reserve(uint64_t sh_offset, uint64_t sh_size)
+{
+  this->free_list_.remove(sh_offset, sh_offset + sh_size);
+}
+
+// Allocate space from the free list for the section.  Used for
+// incremental update links.
+
+off_t
+Output_section::allocate(off_t len, uint64_t addralign)
+{
+  return this->free_list_.allocate(len, addralign, 0);
+}
+
 // Output segment methods.
 
 Output_segment::Output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags)
@@ -3416,7 +4121,8 @@ Output_segment::Output_segment(elfcpp::Elf_Word type, elfcpp::Elf_Word flags)
     flags_(flags),
     is_max_align_known_(false),
     are_addresses_set_(false),
-    is_large_data_segment_(false)
+    is_large_data_segment_(false),
+    is_unique_segment_(false)
 {
   // The ELF ABI specifies that a PT_TLS segment always has PF_R as
   // the flags.
@@ -3518,13 +4224,16 @@ Output_segment::has_any_data_sections() const
   return false;
 }
 
-// Return whether the first data section is a relro section.
+// Return whether the first data section (not counting TLS sections)
+// is a relro section.
 
 bool
 Output_segment::is_first_section_relro() const
 {
   for (int i = 0; i < static_cast<int>(ORDER_MAX); ++i)
     {
+      if (i == static_cast<int>(ORDER_TLS_BSS))
+       continue;
       const Output_data_list* pdl = &this->output_lists_[i];
       if (!pdl->empty())
        {
@@ -3543,7 +4252,7 @@ Output_segment::maximum_alignment()
   if (!this->is_max_align_known_)
     {
       for (int i = 0; i < static_cast<int>(ORDER_MAX); ++i)
-       {       
+       {
          const Output_data_list* pdl = &this->output_lists_[i];
          uint64_t addralign = Output_segment::maximum_alignment_list(pdl);
          if (addralign > this->max_align_)
@@ -3599,29 +4308,39 @@ Output_segment::has_dynamic_reloc_list(const Output_data_list* pdl) const
 // Set the section addresses for an Output_segment.  If RESET is true,
 // reset the addresses first.  ADDR is the address and *POFF is the
 // file offset.  Set the section indexes starting with *PSHNDX.
-// Return the address of the immediately following segment.  Update
-// *POFF and *PSHNDX.
+// INCREASE_RELRO is the size of the portion of the first non-relro
+// section that should be included in the PT_GNU_RELRO segment.
+// If this segment has relro sections, and has been aligned for
+// that purpose, set *HAS_RELRO to TRUE.  Return the address of
+// the immediately following segment.  Update *HAS_RELRO, *POFF,
+// and *PSHNDX.
 
 uint64_t
-Output_segment::set_section_addresses(const Layout* layout, bool reset,
-                                      uint64_t addr,
-                                     unsigned int increase_relro,
+Output_segment::set_section_addresses(const Target* target,
+                                     Layout* layout, bool reset,
+                                     uint64_t addr,
+                                     unsigned int* increase_relro,
+                                     bool* has_relro,
                                      off_t* poff,
                                      unsigned int* pshndx)
 {
   gold_assert(this->type_ == elfcpp::PT_LOAD);
 
+  uint64_t last_relro_pad = 0;
   off_t orig_off = *poff;
 
+  bool in_tls = false;
+
   // If we have relro sections, we need to pad forward now so that the
-  // relro sections plus INCREASE_RELRO end on a common page boundary.
+  // relro sections plus INCREASE_RELRO end on an abi page boundary.
   if (parameters->options().relro()
       && this->is_first_section_relro()
       && (!this->are_addresses_set_ || reset))
     {
       uint64_t relro_size = 0;
       off_t off = *poff;
-      for (int i = 0; i < static_cast<int>(ORDER_MAX); ++i)
+      uint64_t max_align = 0;
+      for (int i = 0; i <= static_cast<int>(ORDER_RELRO_LAST); ++i)
        {
          Output_data_list* pdl = &this->output_lists_[i];
          Output_data_list::iterator p;
@@ -3629,16 +4348,30 @@ Output_segment::set_section_addresses(const Layout* layout, bool reset,
            {
              if (!(*p)->is_section())
                break;
-             Output_section* pos = (*p)->output_section();
-             if (!pos->is_relro())
-               break;
+             uint64_t align = (*p)->addralign();
+             if (align > max_align)
+               max_align = align;
+             if ((*p)->is_section_flag_set(elfcpp::SHF_TLS))
+               in_tls = true;
+             else if (in_tls)
+               {
+                 // Align the first non-TLS section to the alignment
+                 // of the TLS segment.
+                 align = max_align;
+                 in_tls = false;
+               }
+             // Ignore the size of the .tbss section.
+             if ((*p)->is_section_flag_set(elfcpp::SHF_TLS)
+                 && (*p)->is_section_type(elfcpp::SHT_NOBITS))
+               continue;
+             relro_size = align_address(relro_size, align);
              if ((*p)->is_address_valid())
                relro_size += (*p)->data_size();
              else
                {
                  // FIXME: This could be faster.
-                 (*p)->set_address_and_file_offset(addr + relro_size,
-                                                   off + relro_size);
+                 (*p)->set_address_and_file_offset(relro_size,
+                                                   relro_size);
                  relro_size += (*p)->data_size();
                  (*p)->reset_address_and_file_offset();
                }
@@ -3646,17 +4379,24 @@ Output_segment::set_section_addresses(const Layout* layout, bool reset,
          if (p != pdl->end())
            break;
        }
-      relro_size += increase_relro;
+      relro_size += *increase_relro;
+      // Pad the total relro size to a multiple of the maximum
+      // section alignment seen.
+      uint64_t aligned_size = align_address(relro_size, max_align);
+      // Note the amount of padding added after the last relro section.
+      last_relro_pad = aligned_size - relro_size;
+      *has_relro = true;
 
-      uint64_t page_align = parameters->target().common_pagesize();
+      uint64_t page_align = parameters->target().abi_pagesize();
 
       // Align to offset N such that (N + RELRO_SIZE) % PAGE_ALIGN == 0.
-      uint64_t desired_align = page_align - (relro_size % page_align);
-      if (desired_align < *poff % page_align)
-       *poff += page_align - *poff % page_align;
-      *poff += desired_align - *poff % page_align;
-      addr += *poff - orig_off;
-      orig_off = *poff;
+      uint64_t desired_align = page_align - (aligned_size % page_align);
+      if (desired_align < off % page_align)
+       off += page_align;
+      off += desired_align - off % page_align;
+      addr += off - orig_off;
+      orig_off = off;
+      *poff = off;
     }
 
   if (!reset && this->are_addresses_set_)
@@ -3671,22 +4411,44 @@ Output_segment::set_section_addresses(const Layout* layout, bool reset,
       this->are_addresses_set_ = true;
     }
 
-  bool in_tls = false;
+  in_tls = false;
 
   this->offset_ = orig_off;
 
   off_t off = 0;
-  uint64_t ret;
+  off_t foff = *poff;
+  uint64_t ret = 0;
   for (int i = 0; i < static_cast<int>(ORDER_MAX); ++i)
     {
-      addr = this->set_section_list_addresses(layout, reset,
-                                             &this->output_lists_[i],
-                                             addr, poff, pshndx, &in_tls);
-      if (i < static_cast<int>(ORDER_SMALL_BSS))
+      if (i == static_cast<int>(ORDER_RELRO_LAST))
        {
-         this->filesz_ = *poff - orig_off;
-         off = *poff;
+         *poff += last_relro_pad;
+         foff += last_relro_pad;
+         addr += last_relro_pad;
+         if (this->output_lists_[i].empty())
+           {
+             // If there is nothing in the ORDER_RELRO_LAST list,
+             // the padding will occur at the end of the relro
+             // segment, and we need to add it to *INCREASE_RELRO.
+             *increase_relro += last_relro_pad;
+           }
        }
+      addr = this->set_section_list_addresses(layout, reset,
+                                             &this->output_lists_[i],
+                                             addr, poff, &foff, pshndx,
+                                             &in_tls);
+
+      // FOFF tracks the last offset used for the file image,
+      // and *POFF tracks the last offset used for the memory image.
+      // When not using a linker script, bss sections should all
+      // be processed in the ORDER_SMALL_BSS and later buckets.
+      gold_assert(*poff == foff
+                 || i == static_cast<int>(ORDER_TLS_BSS)
+                 || i >= static_cast<int>(ORDER_SMALL_BSS)
+                 || layout->script_options()->saw_sections_clause());
+
+      this->filesz_ = foff - orig_off;
+      off = foff;
 
       ret = addr;
     }
@@ -3706,6 +4468,41 @@ Output_segment::set_section_addresses(const Layout* layout, bool reset,
   // objects.
   *poff = off;
 
+  // If code segments must contain only code, and this code segment is
+  // page-aligned in the file, then fill it out to a whole page with
+  // code fill (the tail of the segment will not be within any section).
+  // Thus the entire code segment can be mapped from the file as whole
+  // pages and that mapping will contain only valid instructions.
+  if (target->isolate_execinstr() && (this->flags() & elfcpp::PF_X) != 0)
+    {
+      uint64_t abi_pagesize = target->abi_pagesize();
+      if (orig_off % abi_pagesize == 0 && off % abi_pagesize != 0)
+       {
+         size_t fill_size = abi_pagesize - (off % abi_pagesize);
+
+         std::string fill_data;
+         if (target->has_code_fill())
+           fill_data = target->code_fill(fill_size);
+         else
+           fill_data.resize(fill_size); // Zero fill.
+
+         Output_data_const* fill = new Output_data_const(fill_data, 0);
+         fill->set_address(this->vaddr_ + this->memsz_);
+         fill->set_file_offset(off);
+         layout->add_relax_output(fill);
+
+         off += fill_size;
+         gold_assert(off % abi_pagesize == 0);
+         ret += fill_size;
+         gold_assert(ret % abi_pagesize == 0);
+
+         gold_assert((uint64_t) this->filesz_ == this->memsz_);
+         this->memsz_ = this->filesz_ += fill_size;
+
+         *poff = off;
+       }
+    }
+
   return ret;
 }
 
@@ -3713,70 +4510,122 @@ Output_segment::set_section_addresses(const Layout* layout, bool reset,
 // structures.
 
 uint64_t
-Output_segment::set_section_list_addresses(const Layout* layout, bool reset,
-                                           Output_data_list* pdl,
+Output_segment::set_section_list_addresses(Layout* layout, bool reset,
+                                          Output_data_list* pdl,
                                           uint64_t addr, off_t* poff,
+                                          off_t* pfoff,
                                           unsigned int* pshndx,
-                                           bool* in_tls)
+                                          bool* in_tls)
 {
   off_t startoff = *poff;
+  // For incremental updates, we may allocate non-fixed sections from
+  // free space in the file.  This keeps track of the high-water mark.
+  off_t maxoff = startoff;
 
   off_t off = startoff;
+  off_t foff = *pfoff;
   for (Output_data_list::iterator p = pdl->begin();
        p != pdl->end();
        ++p)
     {
+      bool is_bss = (*p)->is_section_type(elfcpp::SHT_NOBITS);
+      bool is_tls = (*p)->is_section_flag_set(elfcpp::SHF_TLS);
+
       if (reset)
        (*p)->reset_address_and_file_offset();
 
-      // When using a linker script the section will most likely
-      // already have an address.
+      // When doing an incremental update or when using a linker script,
+      // the section will most likely already have an address.
       if (!(*p)->is_address_valid())
        {
-          uint64_t align = (*p)->addralign();
-
-          if ((*p)->is_section_flag_set(elfcpp::SHF_TLS))
-            {
-              // Give the first TLS section the alignment of the
-              // entire TLS segment.  Otherwise the TLS segment as a
-              // whole may be misaligned.
-              if (!*in_tls)
-                {
-                  Output_segment* tls_segment = layout->tls_segment();
-                  gold_assert(tls_segment != NULL);
-                  uint64_t segment_align = tls_segment->maximum_alignment();
-                  gold_assert(segment_align >= align);
-                  align = segment_align;
-
-                  *in_tls = true;
-                }
-            }
-          else
-            {
-              // If this is the first section after the TLS segment,
-              // align it to at least the alignment of the TLS
-              // segment, so that the size of the overall TLS segment
-              // is aligned.
-              if (*in_tls)
-                {
-                  uint64_t segment_align =
-                      layout->tls_segment()->maximum_alignment();
-                  if (segment_align > align)
-                    align = segment_align;
-
-                  *in_tls = false;
-                }
-            }
-
-         off = align_address(off, align);
-         (*p)->set_address_and_file_offset(addr + (off - startoff), off);
+         uint64_t align = (*p)->addralign();
+
+         if (is_tls)
+           {
+             // Give the first TLS section the alignment of the
+             // entire TLS segment.  Otherwise the TLS segment as a
+             // whole may be misaligned.
+             if (!*in_tls)
+               {
+                 Output_segment* tls_segment = layout->tls_segment();
+                 gold_assert(tls_segment != NULL);
+                 uint64_t segment_align = tls_segment->maximum_alignment();
+                 gold_assert(segment_align >= align);
+                 align = segment_align;
+
+                 *in_tls = true;
+               }
+           }
+         else
+           {
+             // If this is the first section after the TLS segment,
+             // align it to at least the alignment of the TLS
+             // segment, so that the size of the overall TLS segment
+             // is aligned.
+             if (*in_tls)
+               {
+                 uint64_t segment_align =
+                     layout->tls_segment()->maximum_alignment();
+                 if (segment_align > align)
+                   align = segment_align;
+
+                 *in_tls = false;
+               }
+           }
+
+         if (!parameters->incremental_update())
+           {
+             gold_assert(off == foff || is_bss);
+             off = align_address(off, align);
+             if (is_tls || !is_bss)
+               foff = off;
+             (*p)->set_address_and_file_offset(addr + (off - startoff), foff);
+           }
+         else
+           {
+             // Incremental update: allocate file space from free list.
+             (*p)->pre_finalize_data_size();
+             off_t current_size = (*p)->current_data_size();
+             off = layout->allocate(current_size, align, startoff);
+             foff = off;
+             if (off == -1)
+               {
+                 gold_assert((*p)->output_section() != NULL);
+                 gold_fallback(_("out of patch space for section %s; "
+                                 "relink with --incremental-full"),
+                               (*p)->output_section()->name());
+               }
+             (*p)->set_address_and_file_offset(addr + (off - startoff), foff);
+             if ((*p)->data_size() > current_size)
+               {
+                 gold_assert((*p)->output_section() != NULL);
+                 gold_fallback(_("%s: section changed size; "
+                                 "relink with --incremental-full"),
+                               (*p)->output_section()->name());
+               }
+           }
+       }
+      else if (parameters->incremental_update())
+       {
+         // For incremental updates, use the fixed offset for the
+         // high-water mark computation.
+         off = (*p)->offset();
+         foff = off;
        }
       else
        {
          // The script may have inserted a skip forward, but it
          // better not have moved backward.
          if ((*p)->address() >= addr + (off - startoff))
-           off += (*p)->address() - (addr + (off - startoff));
+           {
+             if (!is_bss && off > foff)
+               gold_warning(_("script places BSS section in the middle "
+                              "of a LOAD segment; space will be allocated "
+                              "in the file"));
+             off += (*p)->address() - (addr + (off - startoff));
+             if (is_tls || !is_bss)
+               foff = off;
+           }
          else
            {
              if (!layout->script_options()->saw_sections_clause())
@@ -3800,17 +4649,32 @@ Output_segment::set_section_list_addresses(const Layout* layout, bool reset,
                               os->name(), previous_dot, dot);
                }
            }
-         (*p)->set_file_offset(off);
+         (*p)->set_file_offset(foff);
          (*p)->finalize_data_size();
        }
 
-      // We want to ignore the size of a SHF_TLS or SHT_NOBITS
+      if (parameters->incremental_update())
+       gold_debug(DEBUG_INCREMENTAL,
+                  "set_section_list_addresses: %08lx %08lx %s",
+                  static_cast<long>(off),
+                  static_cast<long>((*p)->data_size()),
+                  ((*p)->output_section() != NULL
+                   ? (*p)->output_section()->name() : "(special)"));
+
+      // We want to ignore the size of a SHF_TLS SHT_NOBITS
       // section.  Such a section does not affect the size of a
       // PT_LOAD segment.
-      if (!(*p)->is_section_flag_set(elfcpp::SHF_TLS)
-         || !(*p)->is_section_type(elfcpp::SHT_NOBITS))
+      if (!is_tls || !is_bss)
        off += (*p)->data_size();
 
+      // We don't allocate space in the file for SHT_NOBITS sections,
+      // unless a script has force-placed one in the middle of a segment.
+      if (!is_bss)
+       foff = off;
+
+      if (off > maxoff)
+       maxoff = off;
+
       if ((*p)->is_section())
        {
          (*p)->set_out_shndx(*pshndx);
@@ -3818,8 +4682,9 @@ Output_segment::set_section_list_addresses(const Layout* layout, bool reset,
        }
     }
 
-  *poff = off;
-  return addr + (off - startoff);
+  *poff = maxoff;
+  *pfoff = foff;
+  return addr + (maxoff - startoff);
 }
 
 // For a non-PT_LOAD segment, set the offset from the sections, if
@@ -3897,6 +4762,23 @@ Output_segment::set_offset(unsigned int increase)
   this->filesz_ += increase;
   this->memsz_ += increase;
 
+  // If this is a RELRO segment, verify that the segment ends at a
+  // page boundary.
+  if (this->type_ == elfcpp::PT_GNU_RELRO)
+    {
+      uint64_t page_align = parameters->target().abi_pagesize();
+      uint64_t segment_end = this->vaddr_ + this->memsz_;
+      if (parameters->incremental_update())
+       {
+         // The INCREASE_RELRO calculation is bypassed for an incremental
+         // update, so we need to adjust the segment size manually here.
+         segment_end = align_address(segment_end, page_align);
+         this->memsz_ = segment_end - this->vaddr_;
+       }
+      else
+       gold_assert(segment_end == align_address(segment_end, page_align));
+    }
+
   // If this is a TLS segment, align the memory size.  The code in
   // set_section_list ensures that the section after the TLS segment
   // is aligned to give us room.
@@ -3921,10 +4803,10 @@ Output_segment::set_tls_offsets()
     (*p)->set_tls_offset(this->vaddr_);
 }
 
-// Return the load address of the first section.
+// Return the first section.
 
-uint64_t
-Output_segment::first_section_load_address() const
+Output_section*
+Output_segment::first_section() const
 {
   for (int i = 0; i < static_cast<int>(ORDER_MAX); ++i)
     {
@@ -3934,12 +4816,10 @@ Output_segment::first_section_load_address() const
           ++p)
        {
          if ((*p)->is_section())
-           return ((*p)->has_load_address()
-                   ? (*p)->load_address()
-                   : (*p)->address());
+           return (*p)->output_section();
        }
     }
-  gold_unreachable();
+  return NULL;
 }
 
 // Return the number of Output_sections in an Output_segment.
@@ -4032,7 +4912,7 @@ unsigned char*
 Output_segment::write_section_headers(const Layout* layout,
                                      const Stringpool* secnamepool,
                                      unsigned char* v,
-                                     unsigned int *pshndx) const
+                                     unsigned intpshndx) const
 {
   // Every section that is attached to a segment must be attached to a
   // PT_LOAD segment, so we only write out section headers for PT_LOAD
@@ -4109,36 +4989,93 @@ Output_file::Output_file(const char* name)
     file_size_(0),
     base_(NULL),
     map_is_anonymous_(false),
+    map_is_allocated_(false),
     is_temporary_(false)
 {
 }
 
 // Try to open an existing file.  Returns false if the file doesn't
-// exist, has a size of 0 or can't be mmapped.
+// exist, has a size of 0 or can't be mmapped.  If BASE_NAME is not
+// NULL, open that file as the base for incremental linking, and
+// copy its contents to the new output file.  This routine can
+// be called for incremental updates, in which case WRITABLE should
+// be true, or by the incremental-dump utility, in which case
+// WRITABLE should be false.
 
 bool
-Output_file::open_for_modification()
+Output_file::open_base_file(const char* base_name, bool writable)
 {
   // The name "-" means "stdout".
   if (strcmp(this->name_, "-") == 0)
     return false;
 
+  bool use_base_file = base_name != NULL;
+  if (!use_base_file)
+    base_name = this->name_;
+  else if (strcmp(base_name, this->name_) == 0)
+    gold_fatal(_("%s: incremental base and output file name are the same"),
+              base_name);
+
   // Don't bother opening files with a size of zero.
   struct stat s;
-  if (::stat(this->name_, &s) != 0 || s.st_size == 0)
-    return false;
+  if (::stat(base_name, &s) != 0)
+    {
+      gold_info(_("%s: stat: %s"), base_name, strerror(errno));
+      return false;
+    }
+  if (s.st_size == 0)
+    {
+      gold_info(_("%s: incremental base file is empty"), base_name);
+      return false;
+    }
 
-  int o = open_descriptor(-1, this->name_, O_RDWR, 0);
+  // If we're using a base file, we want to open it read-only.
+  if (use_base_file)
+    writable = false;
+
+  int oflags = writable ? O_RDWR : O_RDONLY;
+  int o = open_descriptor(-1, base_name, oflags, 0);
   if (o < 0)
-    gold_fatal(_("%s: open: %s"), this->name_, strerror(errno));
+    {
+      gold_info(_("%s: open: %s"), base_name, strerror(errno));
+      return false;
+    }
+
+  // If the base file and the output file are different, open a
+  // new output file and read the contents from the base file into
+  // the newly-mapped region.
+  if (use_base_file)
+    {
+      this->open(s.st_size);
+      ssize_t bytes_to_read = s.st_size;
+      unsigned char* p = this->base_;
+      while (bytes_to_read > 0)
+       {
+         ssize_t len = ::read(o, p, bytes_to_read);
+         if (len < 0)
+           {
+             gold_info(_("%s: read failed: %s"), base_name, strerror(errno));
+             return false;
+           }
+         if (len == 0)
+           {
+             gold_info(_("%s: file too short: read only %lld of %lld bytes"),
+                       base_name,
+                       static_cast<long long>(s.st_size - bytes_to_read),
+                       static_cast<long long>(s.st_size));
+             return false;
+           }
+         p += len;
+         bytes_to_read -= len;
+       }
+      ::close(o);
+      return true;
+    }
+
   this->o_ = o;
   this->file_size_ = s.st_size;
 
-  // If the file can't be mmapped, copying the content to an anonymous
-  // map will probably negate the performance benefits of incremental
-  // linking.  This could be helped by using views and loading only
-  // the necessary parts, but this is not supported as of now.
-  if (!this->map_no_anonymous())
+  if (!this->map_no_anonymous(writable))
     {
       release_descriptor(o, true);
       this->o_ = -1;
@@ -4216,10 +5153,23 @@ Output_file::resize(off_t file_size)
   // to unmap to flush to the file, then remap after growing the file.
   if (this->map_is_anonymous_)
     {
-      void* base = ::mremap(this->base_, this->file_size_, file_size,
-                            MREMAP_MAYMOVE);
-      if (base == MAP_FAILED)
-        gold_fatal(_("%s: mremap: %s"), this->name_, strerror(errno));
+      void* base;
+      if (!this->map_is_allocated_)
+       {
+         base = ::mremap(this->base_, this->file_size_, file_size,
+                         MREMAP_MAYMOVE);
+         if (base == MAP_FAILED)
+           gold_fatal(_("%s: mremap: %s"), this->name_, strerror(errno));
+       }
+      else
+       {
+         base = realloc(this->base_, file_size);
+         if (base == NULL)
+           gold_nomem();
+         if (file_size > this->file_size_)
+           memset(static_cast<char*>(base) + this->file_size_, 0,
+                  file_size - this->file_size_);
+       }
       this->base_ = static_cast<unsigned char*>(base);
       this->file_size_ = file_size;
     }
@@ -4227,7 +5177,7 @@ Output_file::resize(off_t file_size)
     {
       this->unmap();
       this->file_size_ = file_size;
-      if (!this->map_no_anonymous())
+      if (!this->map_no_anonymous(true))
        gold_fatal(_("%s: mmap: %s"), this->name_, strerror(errno));
     }
 }
@@ -4240,19 +5190,24 @@ Output_file::map_anonymous()
 {
   void* base = ::mmap(NULL, this->file_size_, PROT_READ | PROT_WRITE,
                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
-  if (base != MAP_FAILED)
+  if (base == MAP_FAILED)
     {
-      this->map_is_anonymous_ = true;
-      this->base_ = static_cast<unsigned char*>(base);
-      return true;
+      base = malloc(this->file_size_);
+      if (base == NULL)
+       return false;
+      memset(base, 0, this->file_size_);
+      this->map_is_allocated_ = true;
     }
-  return false;
+  this->base_ = static_cast<unsigned char*>(base);
+  this->map_is_anonymous_ = true;
+  return true;
 }
 
 // Map the file into memory.  Return whether the mapping succeeded.
+// If WRITABLE is true, map with write access.
 
 bool
-Output_file::map_no_anonymous()
+Output_file::map_no_anonymous(bool writable)
 {
   const int o = this->o_;
 
@@ -4274,12 +5229,18 @@ Output_file::map_no_anonymous()
   // output file will wind up incomplete, but we will have already
   // exited.  The alternative to fallocate would be to use fdatasync,
   // but that would be a more significant performance hit.
-  if (::posix_fallocate(o, 0, this->file_size_) < 0)
-    gold_fatal(_("%s: %s"), this->name_, strerror(errno));
+  if (writable)
+    {
+      int err = gold_fallocate(o, 0, this->file_size_);
+      if (err != 0)
+       gold_fatal(_("%s: %s"), this->name_, strerror(err));
+    }
 
   // Map the file into memory.
-  base = ::mmap(NULL, this->file_size_, PROT_READ | PROT_WRITE,
-               MAP_SHARED, o, 0);
+  int prot = PROT_READ;
+  if (writable)
+    prot |= PROT_WRITE;
+  base = ::mmap(NULL, this->file_size_, prot, MAP_SHARED, o, 0);
 
   // The mmap call might fail because of file system issues: the file
   // system might not support mmap at all, or it might not support
@@ -4297,7 +5258,8 @@ Output_file::map_no_anonymous()
 void
 Output_file::map()
 {
-  if (this->map_no_anonymous())
+  if (parameters->options().mmap_output_file()
+      && this->map_no_anonymous(true))
     return;
 
   // The mmap call might fail because of file system issues: the file
@@ -4309,8 +5271,8 @@ Output_file::map()
     return;
 
   gold_fatal(_("%s: mmap: failed to allocate %lu bytes for output file: %s"),
-             this->name_, static_cast<unsigned long>(this->file_size_),
-             strerror(errno));
+            this->name_, static_cast<unsigned long>(this->file_size_),
+            strerror(errno));
 }
 
 // Unmap the file from memory.
@@ -4318,8 +5280,16 @@ Output_file::map()
 void
 Output_file::unmap()
 {
-  if (::munmap(this->base_, this->file_size_) < 0)
-    gold_error(_("%s: munmap: %s"), this->name_, strerror(errno));
+  if (this->map_is_anonymous_)
+    {
+      // We've already written out the data, so there is no reason to
+      // waste time unmapping or freeing the memory.
+    }
+  else
+    {
+      if (::munmap(this->base_, this->file_size_) < 0)
+       gold_error(_("%s: munmap: %s"), this->name_, strerror(errno));
+    }
   this->base_ = NULL;
 }
 
@@ -4334,19 +5304,19 @@ Output_file::close()
       size_t bytes_to_write = this->file_size_;
       size_t offset = 0;
       while (bytes_to_write > 0)
-        {
-          ssize_t bytes_written = ::write(this->o_, this->base_ + offset,
-                                          bytes_to_write);
-          if (bytes_written == 0)
-            gold_error(_("%s: write: unexpected 0 return-value"), this->name_);
-          else if (bytes_written < 0)
-            gold_error(_("%s: write: %s"), this->name_, strerror(errno));
-          else
-            {
-              bytes_to_write -= bytes_written;
-              offset += bytes_written;
-            }
-        }
+       {
+         ssize_t bytes_written = ::write(this->o_, this->base_ + offset,
+                                         bytes_to_write);
+         if (bytes_written == 0)
+           gold_error(_("%s: write: unexpected 0 return-value"), this->name_);
+         else if (bytes_written < 0)
+           gold_error(_("%s: write: %s"), this->name_, strerror(errno));
+         else
+           {
+             bytes_to_write -= bytes_written;
+             offset += bytes_written;
+           }
+       }
     }
   this->unmap();
 
@@ -4367,7 +5337,7 @@ template
 off_t
 Output_section::add_input_section<32, false>(
     Layout* layout,
-    Sized_relobj<32, false>* object,
+    Sized_relobj_file<32, false>* object,
     unsigned int shndx,
     const char* secname,
     const elfcpp::Shdr<32, false>& shdr,
@@ -4380,7 +5350,7 @@ template
 off_t
 Output_section::add_input_section<32, true>(
     Layout* layout,
-    Sized_relobj<32, true>* object,
+    Sized_relobj_file<32, true>* object,
     unsigned int shndx,
     const char* secname,
     const elfcpp::Shdr<32, true>& shdr,
@@ -4393,7 +5363,7 @@ template
 off_t
 Output_section::add_input_section<64, false>(
     Layout* layout,
-    Sized_relobj<64, false>* object,
+    Sized_relobj_file<64, false>* object,
     unsigned int shndx,
     const char* secname,
     const elfcpp::Shdr<64, false>& shdr,
@@ -4406,7 +5376,7 @@ template
 off_t
 Output_section::add_input_section<64, true>(
     Layout* layout,
-    Sized_relobj<64, true>* object,
+    Sized_relobj_file<64, true>* object,
     unsigned int shndx,
     const char* secname,
     const elfcpp::Shdr<64, true>& shdr,
@@ -4634,24 +5604,16 @@ template
 class Output_data_group<64, true>;
 #endif
 
-#ifdef HAVE_TARGET_32_LITTLE
 template
 class Output_data_got<32, false>;
-#endif
 
-#ifdef HAVE_TARGET_32_BIG
 template
 class Output_data_got<32, true>;
-#endif
 
-#ifdef HAVE_TARGET_64_LITTLE
 template
 class Output_data_got<64, false>;
-#endif
 
-#ifdef HAVE_TARGET_64_BIG
 template
 class Output_data_got<64, true>;
-#endif
 
 } // End namespace gold.
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