Add -Wshadow to the gcc command line options used when compiling the binutils.
[deliverable/binutils-gdb.git] / gold / object.cc
index 795fa8bf1b0b96410084adb01bed77ede6f27892..465e99c7ca72031e6dd400aae8e0b2862b4aebeb 100644 (file)
@@ -1,6 +1,6 @@
 // object.cc -- support for an object file for linking in gold
 
-// Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
+// Copyright 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
 // Written by Ian Lance Taylor <iant@google.com>.
 
 // This file is part of gold.
 #include "demangle.h"
 #include "libiberty.h"
 
+#include "gc.h"
 #include "target-select.h"
 #include "dwarf_reader.h"
 #include "layout.h"
 #include "output.h"
 #include "symtab.h"
+#include "cref.h"
 #include "reloc.h"
 #include "object.h"
 #include "dynobj.h"
+#include "plugin.h"
 
 namespace gold
 {
 
-// Class Object.
+// Class Xindex.
 
-// Set the target based on fields in the ELF file header.
+// Initialize the symtab_xindex_ array.  Find the SHT_SYMTAB_SHNDX
+// section and read it in.  SYMTAB_SHNDX is the index of the symbol
+// table we care about.
 
+template<int size, bool big_endian>
 void
-Object::set_target(int machine, int size, bool big_endian, int osabi,
-                  int abiversion)
+Xindex::initialize_symtab_xindex(Object* object, unsigned int sym_tab_shndx)
 {
-  Target* target = select_target(machine, size, big_endian, osabi, abiversion);
-  if (target == NULL)
-    gold_fatal(_("%s: unsupported ELF machine number %d"),
-              this->name().c_str(), machine);
-  this->target_ = target;
+  if (!this->symtab_xindex_.empty())
+    return;
+
+  gold_assert(sym_tab_shndx != 0);
+
+  // Look through the sections in reverse order, on the theory that it
+  // is more likely to be near the end than the beginning.
+  unsigned int i = object->shnum();
+  while (i > 0)
+    {
+      --i;
+      if (object->section_type(i) == elfcpp::SHT_SYMTAB_SHNDX
+         && this->adjust_shndx(object->section_link(i)) == sym_tab_shndx)
+       {
+         this->read_symtab_xindex<size, big_endian>(object, i, NULL);
+         return;
+       }
+    }
+
+  object->error(_("missing SHT_SYMTAB_SHNDX section"));
+}
+
+// Read in the symtab_xindex_ array, given the section index of the
+// SHT_SYMTAB_SHNDX section.  If PSHDRS is not NULL, it points at the
+// section headers.
+
+template<int size, bool big_endian>
+void
+Xindex::read_symtab_xindex(Object* object, unsigned int xindex_shndx,
+                          const unsigned char* pshdrs)
+{
+  section_size_type bytecount;
+  const unsigned char* contents;
+  if (pshdrs == NULL)
+    contents = object->section_contents(xindex_shndx, &bytecount, false);
+  else
+    {
+      const unsigned char* p = (pshdrs
+                               + (xindex_shndx
+                                  * elfcpp::Elf_sizes<size>::shdr_size));
+      typename elfcpp::Shdr<size, big_endian> shdr(p);
+      bytecount = convert_to_section_size_type(shdr.get_sh_size());
+      contents = object->get_view(shdr.get_sh_offset(), bytecount, true, false);
+    }
+
+  gold_assert(this->symtab_xindex_.empty());
+  this->symtab_xindex_.reserve(bytecount / 4);
+  for (section_size_type i = 0; i < bytecount; i += 4)
+    {
+      unsigned int shndx = elfcpp::Swap<32, big_endian>::readval(contents + i);
+      // We preadjust the section indexes we save.
+      this->symtab_xindex_.push_back(this->adjust_shndx(shndx));
+    }
+}
+
+// Symbol symndx has a section of SHN_XINDEX; return the real section
+// index.
+
+unsigned int
+Xindex::sym_xindex_to_shndx(Object* object, unsigned int symndx)
+{
+  if (symndx >= this->symtab_xindex_.size())
+    {
+      object->error(_("symbol %u out of range for SHT_SYMTAB_SHNDX section"),
+                   symndx);
+      return elfcpp::SHN_UNDEF;
+    }
+  unsigned int shndx = this->symtab_xindex_[symndx];
+  if (shndx < elfcpp::SHN_LORESERVE || shndx >= object->shnum())
+    {
+      object->error(_("extended index for symbol %u out of range: %u"),
+                   symndx, shndx);
+      return elfcpp::SHN_UNDEF;
+    }
+  return shndx;
 }
 
+// Class Object.
+
 // Report an error for this object file.  This is used by the
 // elfcpp::Elf_file interface, and also called by the Object code
 // itself.
@@ -80,7 +157,12 @@ Object::section_contents(unsigned int shndx, section_size_type* plen,
 {
   Location loc(this->do_section_contents(shndx));
   *plen = convert_to_section_size_type(loc.data_size);
-  return this->get_view(loc.file_offset, *plen, cache);
+  if (*plen == 0)
+    {
+      static const unsigned char empty[1] = { '\0' };
+      return empty;
+    }
+  return this->get_view(loc.file_offset, *plen, true, cache);
 }
 
 // Read the section data into SD.  This is code common to Sized_relobj
@@ -95,8 +177,9 @@ Object::read_section_data(elfcpp::Elf_file<size, big_endian, Object>* elf_file,
 
   // Read the section headers.
   const off_t shoff = elf_file->shoff();
-  const unsigned int shnum = this->shnum();
-  sd->section_headers = this->get_lasting_view(shoff, shnum * shdr_size, true);
+  const unsigned int sec_shnum = this->shnum();
+  sd->section_headers = this->get_lasting_view(shoff, sec_shnum * shdr_size,
+                                              true, true);
 
   // Read the section names.
   const unsigned char* pshdrs = sd->section_headers->data();
@@ -110,20 +193,21 @@ Object::read_section_data(elfcpp::Elf_file<size, big_endian, Object>* elf_file,
   sd->section_names_size =
     convert_to_section_size_type(shdrnames.get_sh_size());
   sd->section_names = this->get_lasting_view(shdrnames.get_sh_offset(),
-                                            sd->section_names_size, false);
+                                            sd->section_names_size, false,
+                                            false);
 }
 
-// If NAME is the name of a special .gnu.warning section, arrange for
+// If SNAME is the name of a special .gnu.warning section, arrange for
 // the warning to be issued.  SHNDX is the section index.  Return
 // whether it is a warning section.
 
 bool
-Object::handle_gnu_warning_section(const char* name, unsigned int shndx,
+Object::handle_gnu_warning_section(const char* sname, unsigned int shndx,
                                   Symbol_table* symtab)
 {
   const char warn_prefix[] = ".gnu.warning.";
   const int warn_prefix_len = sizeof warn_prefix - 1;
-  if (strncmp(name, warn_prefix, warn_prefix_len) == 0)
+  if (strncmp(sname, warn_prefix, warn_prefix_len) == 0)
     {
       // Read the section contents to get the warning text.  It would
       // be nicer if we only did this if we have to actually issue a
@@ -134,33 +218,134 @@ Object::handle_gnu_warning_section(const char* name, unsigned int shndx,
       section_size_type len;
       const unsigned char* contents = this->section_contents(shndx, &len,
                                                             false);
+      if (len == 0)
+       {
+         const char* warning = sname + warn_prefix_len;
+         contents = reinterpret_cast<const unsigned char*>(warning);
+         len = strlen(warning);
+       }
       std::string warning(reinterpret_cast<const char*>(contents), len);
-      symtab->add_warning(name + warn_prefix_len, this, warning);
+      symtab->add_warning(sname + warn_prefix_len, this, warning);
+      return true;
+    }
+  return false;
+}
+
+// If SNAME is the name of the special section which indicates that
+// this object was compiled with -fstack-split, mark it accordingly.
+
+bool
+Object::handle_split_stack_section(const char* sname)
+{
+  if (strcmp(sname, ".note.GNU-split-stack") == 0)
+    {
+      this->uses_split_stack_ = true;
+      return true;
+    }
+  if (strcmp(sname, ".note.GNU-no-split-stack") == 0)
+    {
+      this->has_no_split_stack_ = true;
       return true;
     }
   return false;
 }
 
+// Class Relobj
+
+// To copy the symbols data read from the file to a local data structure.
+// This function is called from do_layout only while doing garbage 
+// collection.
+
+void
+Relobj::copy_symbols_data(Symbols_data* gc_sd, Read_symbols_data* sd, 
+                          unsigned int section_header_size)
+{
+  gc_sd->section_headers_data = 
+         new unsigned char[(section_header_size)];
+  memcpy(gc_sd->section_headers_data, sd->section_headers->data(),
+         section_header_size);
+  gc_sd->section_names_data = 
+         new unsigned char[sd->section_names_size];
+  memcpy(gc_sd->section_names_data, sd->section_names->data(),
+         sd->section_names_size);
+  gc_sd->section_names_size = sd->section_names_size;
+  if (sd->symbols != NULL)
+    {
+      gc_sd->symbols_data = 
+             new unsigned char[sd->symbols_size];
+      memcpy(gc_sd->symbols_data, sd->symbols->data(),
+            sd->symbols_size);
+    }
+  else
+    {
+      gc_sd->symbols_data = NULL;
+    }
+  gc_sd->symbols_size = sd->symbols_size;
+  gc_sd->external_symbols_offset = sd->external_symbols_offset;
+  if (sd->symbol_names != NULL)
+    {
+      gc_sd->symbol_names_data =
+             new unsigned char[sd->symbol_names_size];
+      memcpy(gc_sd->symbol_names_data, sd->symbol_names->data(),
+            sd->symbol_names_size);
+    }
+  else
+    {
+      gc_sd->symbol_names_data = NULL;
+    }
+  gc_sd->symbol_names_size = sd->symbol_names_size;
+}
+
+// This function determines if a particular section name must be included
+// in the link.  This is used during garbage collection to determine the
+// roots of the worklist.
+
+bool
+Relobj::is_section_name_included(const char* sname)
+{
+  if (is_prefix_of(".ctors", sname) 
+      || is_prefix_of(".dtors", sname) 
+      || is_prefix_of(".note", sname) 
+      || is_prefix_of(".init", sname) 
+      || is_prefix_of(".fini", sname) 
+      || is_prefix_of(".gcc_except_table", sname) 
+      || is_prefix_of(".jcr", sname) 
+      || is_prefix_of(".preinit_array", sname) 
+      || (is_prefix_of(".text", sname) 
+          && strstr(sname, "personality")) 
+      || (is_prefix_of(".data", sname) 
+          &&  strstr(sname, "personality")) 
+      || (is_prefix_of(".gnu.linkonce.d", sname)
+         &&  strstr(sname, "personality")))
+    {
+      return true; 
+    }
+  return false;
+}
+
 // Class Sized_relobj.
 
 template<int size, bool big_endian>
 Sized_relobj<size, big_endian>::Sized_relobj(
-    const std::string& name,
-    Input_file* input_file,
-    off_t offset,
+    const std::string& aname,
+    Input_file* ainput_file,
+    off_t aoffset,
     const elfcpp::Ehdr<size, big_endian>& ehdr)
-  : Relobj(name, input_file, offset),
+  : Relobj(aname, ainput_file, aoffset),
     elf_file_(this, ehdr),
     symtab_shndx_(-1U),
     local_symbol_count_(0),
     output_local_symbol_count_(0),
     output_local_dynsym_count_(0),
     symbols_(),
+    defined_count_(0),
     local_symbol_offset_(0),
     local_dynsym_offset_(0),
     local_values_(),
     local_got_offsets_(),
-    has_eh_frame_(false)
+    kept_comdat_sections_(),
+    has_eh_frame_(false),
+    discarded_eh_frame_shndx_(-1U)
 {
 }
 
@@ -170,19 +355,14 @@ Sized_relobj<size, big_endian>::~Sized_relobj()
 }
 
 // Set up an object file based on the file header.  This sets up the
-// target and reads the section information.
+// section information.
 
 template<int size, bool big_endian>
 void
-Sized_relobj<size, big_endian>::setup(
-    const elfcpp::Ehdr<size, big_endian>& ehdr)
+Sized_relobj<size, big_endian>::do_setup()
 {
-  this->set_target(ehdr.get_e_machine(), size, big_endian,
-                  ehdr.get_e_ident()[elfcpp::EI_OSABI],
-                  ehdr.get_e_ident()[elfcpp::EI_ABIVERSION]);
-
-  const unsigned int shnum = this->elf_file_.shnum();
-  this->set_shnum(shnum);
+  const unsigned int sec_shnum = this->elf_file_.shnum();
+  this->set_shnum(sec_shnum);
 }
 
 // Find the SHT_SYMTAB section, given the section headers.  The ELF
@@ -194,14 +374,16 @@ template<int size, bool big_endian>
 void
 Sized_relobj<size, big_endian>::find_symtab(const unsigned char* pshdrs)
 {
-  const unsigned int shnum = this->shnum();
+  const unsigned int sec_shnum = this->shnum();
   this->symtab_shndx_ = 0;
-  if (shnum > 0)
+  if (sec_shnum > 0)
     {
       // Look through the sections in reverse order, since gas tends
       // to put the symbol table at the end.
-      const unsigned char* p = pshdrs + shnum * This::shdr_size;
-      unsigned int i = shnum;
+      const unsigned char* p = pshdrs + sec_shnum * This::shdr_size;
+      unsigned int i = sec_shnum;
+      unsigned int xindex_shndx = 0;
+      unsigned int xindex_link = 0;
       while (i > 0)
        {
          --i;
@@ -210,12 +392,43 @@ Sized_relobj<size, big_endian>::find_symtab(const unsigned char* pshdrs)
          if (shdr.get_sh_type() == elfcpp::SHT_SYMTAB)
            {
              this->symtab_shndx_ = i;
+             if (xindex_shndx > 0 && xindex_link == i)
+               {
+                 Xindex* xindex =
+                   new Xindex(this->elf_file_.large_shndx_offset());
+                 xindex->read_symtab_xindex<size, big_endian>(this,
+                                                              xindex_shndx,
+                                                              pshdrs);
+                 this->set_xindex(xindex);
+               }
              break;
            }
+
+         // Try to pick up the SHT_SYMTAB_SHNDX section, if there is
+         // one.  This will work if it follows the SHT_SYMTAB
+         // section.
+         if (shdr.get_sh_type() == elfcpp::SHT_SYMTAB_SHNDX)
+           {
+             xindex_shndx = i;
+             xindex_link = this->adjust_shndx(shdr.get_sh_link());
+           }
        }
     }
 }
 
+// Return the Xindex structure to use for object with lots of
+// sections.
+
+template<int size, bool big_endian>
+Xindex*
+Sized_relobj<size, big_endian>::do_initialize_xindex()
+{
+  gold_assert(this->symtab_shndx_ != -1U);
+  Xindex* xindex = new Xindex(this->elf_file_.large_shndx_offset());
+  xindex->initialize_symtab_xindex<size, big_endian>(this, this->symtab_shndx_);
+  return xindex;
+}
+
 // Return whether SHDR has the right type and flags to be a GNU
 // .eh_frame section.
 
@@ -224,8 +437,7 @@ bool
 Sized_relobj<size, big_endian>::check_eh_frame_flags(
     const elfcpp::Shdr<size, big_endian>* shdr) const
 {
-  return (shdr->get_sh_size() > 0
-         && shdr->get_sh_type() == elfcpp::SHT_PROGBITS
+  return (shdr->get_sh_type() == elfcpp::SHT_PROGBITS
          && (shdr->get_sh_flags() & elfcpp::SHF_ALLOC) != 0);
 }
 
@@ -239,9 +451,9 @@ Sized_relobj<size, big_endian>::find_eh_frame(
     const char* names,
     section_size_type names_size) const
 {
-  const unsigned int shnum = this->shnum();
+  const unsigned int sec_shnum = this->shnum();
   const unsigned char* p = pshdrs + This::shdr_size;
-  for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size)
+  for (unsigned int i = 1; i < sec_shnum; ++i, p += This::shdr_size)
     {
       typename This::Shdr shdr(p);
       if (this->check_eh_frame_flags(&shdr))
@@ -253,8 +465,8 @@ Sized_relobj<size, big_endian>::find_eh_frame(
              continue;
            }
 
-         const char* name = names + shdr.get_sh_name();
-         if (strcmp(name, ".eh_frame") == 0)
+         const char* aname = names + shdr.get_sh_name();
+         if (strcmp(aname, ".eh_frame") == 0)
            return true;
        }
     }
@@ -305,11 +517,11 @@ Sized_relobj<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
   // object file format is over 5 pages that we don't need to read
   // now.
 
-  const int sym_size = This::sym_size;
+  const int symsize = This::sym_size;
   const unsigned int loccount = symtabshdr.get_sh_info();
   this->local_symbol_count_ = loccount;
   this->local_values_.resize(loccount);
-  section_offset_type locsize = loccount * sym_size;
+  section_offset_type locsize = loccount * symsize;
   off_t dataoff = symtabshdr.get_sh_offset();
   section_size_type datasize =
     convert_to_section_size_type(symtabshdr.get_sh_size());
@@ -319,10 +531,16 @@ Sized_relobj<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
   off_t readoff = this->has_eh_frame_ ? dataoff : extoff;
   section_size_type readsize = this->has_eh_frame_ ? datasize : extsize;
 
-  File_view* fvsymtab = this->get_lasting_view(readoff, readsize, false);
+  if (readsize == 0)
+    {
+      // No external symbols.  Also weird but also legal.
+      return;
+    }
+
+  File_view* fvsymtab = this->get_lasting_view(readoff, readsize, true, false);
 
   // Read the section header for the symbol names.
-  unsigned int strtab_shndx = symtabshdr.get_sh_link();
+  unsigned int strtab_shndx = this->adjust_shndx(symtabshdr.get_sh_link());
   if (strtab_shndx >= this->shnum())
     {
       this->error(_("invalid symbol table name index: %u"), strtab_shndx);
@@ -338,7 +556,8 @@ Sized_relobj<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
 
   // Read the symbol names.
   File_view* fvstrtab = this->get_lasting_view(strtabshdr.get_sh_offset(),
-                                              strtabshdr.get_sh_size(), true);
+                                              strtabshdr.get_sh_size(),
+                                              false, true);
 
   sd->symbols = fvsymtab;
   sd->symbols_size = readsize;
@@ -349,14 +568,17 @@ Sized_relobj<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
 }
 
 // Return the section index of symbol SYM.  Set *VALUE to its value in
-// the object file.  Note that for a symbol which is not defined in
-// this object file, this will set *VALUE to 0 and return SHN_UNDEF;
-// it will not return the final value of the symbol in the link.
+// the object file.  Set *IS_ORDINARY if this is an ordinary section
+// index.  not a special cod between SHN_LORESERVE and SHN_HIRESERVE.
+// Note that for a symbol which is not defined in this object file,
+// this will set *VALUE to 0 and return SHN_UNDEF; it will not return
+// the final value of the symbol in the link.
 
 template<int size, bool big_endian>
 unsigned int
 Sized_relobj<size, big_endian>::symbol_section_and_value(unsigned int sym,
-                                                        Address* value)
+                                                        Address* value,
+                                                        bool* is_ordinary)
 {
   section_size_type symbols_size;
   const unsigned char* symbols = this->section_contents(this->symtab_shndx_,
@@ -368,8 +590,8 @@ Sized_relobj<size, big_endian>::symbol_section_and_value(unsigned int sym,
 
   elfcpp::Sym<size, big_endian> elfsym(symbols + sym * This::sym_size);
   *value = elfsym.get_st_value();
-  // FIXME: Handle SHN_XINDEX.
-  return elfsym.get_st_shndx();
+
+  return this->adjust_sym_shndx(sym, elfsym.get_st_shndx(), is_ordinary);
 }
 
 // Return whether to include a section group in the link.  LAYOUT is
@@ -382,15 +604,18 @@ template<int size, bool big_endian>
 bool
 Sized_relobj<size, big_endian>::include_section_group(
     Symbol_table* symtab,
-    Layout* layout,
+    Layout* alayout,
     unsigned int index,
-    const char* name,
-    const elfcpp::Shdr<size, big_endian>& shdr,
+    const char* aname,
+    const unsigned char* shdrs,
+    const char* section_names,
+    section_size_type section_names_size,
     std::vector<bool>* omit)
 {
   // Read the section contents.
+  typename This::Shdr shdr(shdrs + index * This::shdr_size);
   const unsigned char* pcon = this->get_view(shdr.get_sh_offset(),
-                                            shdr.get_sh_size(), false);
+                                            shdr.get_sh_size(), true, false);
   const elfcpp::Elf_Word* pword =
     reinterpret_cast<const elfcpp::Elf_Word*>(pcon);
 
@@ -406,77 +631,171 @@ Sized_relobj<size, big_endian>::include_section_group(
 
   // Get the appropriate symbol table header (this will normally be
   // the single SHT_SYMTAB section, but in principle it need not be).
-  const unsigned int link = shdr.get_sh_link();
+  const unsigned int link = this->adjust_shndx(shdr.get_sh_link());
   typename This::Shdr symshdr(this, this->elf_file_.section_header(link));
 
   // Read the symbol table entry.
-  if (shdr.get_sh_info() >= symshdr.get_sh_size() / This::sym_size)
+  unsigned int symndx = shdr.get_sh_info();
+  if (symndx >= symshdr.get_sh_size() / This::sym_size)
     {
       this->error(_("section group %u info %u out of range"),
-                 index, shdr.get_sh_info());
+                 index, symndx);
       return false;
     }
-  off_t symoff = symshdr.get_sh_offset() + shdr.get_sh_info() * This::sym_size;
-  const unsigned char* psym = this->get_view(symoff, This::sym_size, false);
+  off_t symoff = symshdr.get_sh_offset() + symndx * This::sym_size;
+  const unsigned char* psym = this->get_view(symoff, This::sym_size, true,
+                                            false);
   elfcpp::Sym<size, big_endian> sym(psym);
 
   // Read the symbol table names.
   section_size_type symnamelen;
   const unsigned char* psymnamesu;
-  psymnamesu = this->section_contents(symshdr.get_sh_link(), &symnamelen,
-                                     true);
+  psymnamesu = this->section_contents(this->adjust_shndx(symshdr.get_sh_link()),
+                                     &symnamelen, true);
   const char* psymnames = reinterpret_cast<const char*>(psymnamesu);
 
   // Get the section group signature.
   if (sym.get_st_name() >= symnamelen)
     {
       this->error(_("symbol %u name offset %u out of range"),
-                 shdr.get_sh_info(), sym.get_st_name());
+                 symndx, sym.get_st_name());
       return false;
     }
 
-  const char* signature = psymnames + sym.get_st_name();
+  std::string signature(psymnames + sym.get_st_name());
 
   // It seems that some versions of gas will create a section group
   // associated with a section symbol, and then fail to give a name to
   // the section symbol.  In such a case, use the name of the section.
-  // FIXME.
-  std::string secname;
   if (signature[0] == '\0' && sym.get_st_type() == elfcpp::STT_SECTION)
     {
-      secname = this->section_name(sym.get_st_shndx());
-      signature = secname.c_str();
+      bool is_ordinary;
+      unsigned int sym_shndx = this->adjust_sym_shndx(symndx,
+                                                     sym.get_st_shndx(),
+                                                     &is_ordinary);
+      if (!is_ordinary || sym_shndx >= this->shnum())
+       {
+         this->error(_("symbol %u invalid section index %u"),
+                     symndx, sym_shndx);
+         return false;
+       }
+      typename This::Shdr member_shdr(shdrs + sym_shndx * This::shdr_size);
+      if (member_shdr.get_sh_name() < section_names_size)
+        signature = section_names + member_shdr.get_sh_name();
     }
 
-  // Record this section group, and see whether we've already seen one
-  // with the same signature.
+  // Record this section group in the layout, and see whether we've already
+  // seen one with the same signature.
+  bool include_group;
+  bool is_comdat;
+  Kept_section* kept_section = NULL;
 
-  if ((flags & elfcpp::GRP_COMDAT) == 0
-      || layout->add_comdat(signature, true))
+  if ((flags & elfcpp::GRP_COMDAT) == 0)
     {
-      if (parameters->options().relocatable())
-       layout->layout_group(symtab, this, index, name, signature, shdr,
-                            pword);
-      return true;
+      include_group = true;
+      is_comdat = false;
+    }
+  else
+    {
+      include_group = alayout->find_or_add_kept_section(signature,
+                                                       this, index, true,
+                                                       true, &kept_section);
+      is_comdat = true;
     }
 
-  // This is a duplicate.  We want to discard the sections in this
-  // group.
   size_t count = shdr.get_sh_size() / sizeof(elfcpp::Elf_Word);
+
+  std::vector<unsigned int> shndxes;
+  bool relocate_group = include_group && parameters->options().relocatable();
+  if (relocate_group)
+    shndxes.reserve(count - 1);
+
   for (size_t i = 1; i < count; ++i)
     {
-      elfcpp::Elf_Word secnum =
-       elfcpp::Swap<32, big_endian>::readval(pword + i);
-      if (secnum >= this->shnum())
+      elfcpp::Elf_Word shndx =
+       this->adjust_shndx(elfcpp::Swap<32, big_endian>::readval(pword + i));
+
+      if (relocate_group)
+       shndxes.push_back(shndx);
+
+      if (shndx >= this->shnum())
        {
          this->error(_("section %u in section group %u out of range"),
-                     secnum, index);
+                     shndx, index);
          continue;
        }
-      (*omit)[secnum] = true;
+
+      // Check for an earlier section number, since we're going to get
+      // it wrong--we may have already decided to include the section.
+      if (shndx < index)
+        this->error(_("invalid section group %u refers to earlier section %u"),
+                    index, shndx);
+
+      // Get the name of the member section.
+      typename This::Shdr member_shdr(shdrs + shndx * This::shdr_size);
+      if (member_shdr.get_sh_name() >= section_names_size)
+        {
+          // This is an error, but it will be diagnosed eventually
+          // in do_layout, so we don't need to do anything here but
+          // ignore it.
+          continue;
+        }
+      std::string mname(section_names + member_shdr.get_sh_name());
+
+      if (include_group)
+       {
+         if (is_comdat)
+           kept_section->add_comdat_section(mname, shndx,
+                                            member_shdr.get_sh_size());
+       }
+      else
+        {
+          (*omit)[shndx] = true;
+
+         if (is_comdat)
+            {
+             Relobj* kept_object = kept_section->object();
+             if (kept_section->is_comdat())
+               {
+                 // Find the corresponding kept section, and store
+                 // that info in the discarded section table.
+                 unsigned int kept_shndx;
+                 uint64_t kept_size;
+                 if (kept_section->find_comdat_section(mname, &kept_shndx,
+                                                       &kept_size))
+                   {
+                     // We don't keep a mapping for this section if
+                     // it has a different size.  The mapping is only
+                     // used for relocation processing, and we don't
+                     // want to treat the sections as similar if the
+                     // sizes are different.  Checking the section
+                     // size is the approach used by the GNU linker.
+                     if (kept_size == member_shdr.get_sh_size())
+                       this->set_kept_comdat_section(shndx, kept_object,
+                                                     kept_shndx);
+                   }
+               }
+             else
+               {
+                 // The existing section is a linkonce section.  Add
+                 // a mapping if there is exactly one section in the
+                 // group (which is true when COUNT == 2) and if it
+                 // is the same size.
+                 if (count == 2
+                     && (kept_section->linkonce_size()
+                         == member_shdr.get_sh_size()))
+                   this->set_kept_comdat_section(shndx, kept_object,
+                                                 kept_section->shndx());
+               }
+            }
+        }
     }
 
-  return false;
+  if (relocate_group)
+    alayout->layout_group(symtab, this, index, aname, signature.c_str(),
+                         shdr, flags, &shndxes);
+
+  return include_group;
 }
 
 // Whether to include a linkonce section in the link.  NAME is the
@@ -497,10 +816,12 @@ Sized_relobj<size, big_endian>::include_section_group(
 template<int size, bool big_endian>
 bool
 Sized_relobj<size, big_endian>::include_linkonce_section(
-    Layout* layout,
-    const char* name,
-    const elfcpp::Shdr<size, big_endian>&)
+    Layout* alayout,
+    unsigned int index,
+    const char* aname,
+    const elfcpp::Shdr<size, big_endian>& shdr)
 {
+  typename elfcpp::Elf_types<size>::Elf_WXword sh_size = shdr.get_sh_size();
   // In general the symbol name we want will be the string following
   // the last '.'.  However, we have to handle the case of
   // .gnu.linkonce.t.__i686.get_pc_thunk.bx, which was generated by
@@ -511,53 +832,207 @@ Sized_relobj<size, big_endian>::include_linkonce_section(
   // ".gnu.linkonce.d.rel.ro.local".
   const char* const linkonce_t = ".gnu.linkonce.t.";
   const char* symname;
-  if (strncmp(name, linkonce_t, strlen(linkonce_t)) == 0)
-    symname = name + strlen(linkonce_t);
+  if (strncmp(aname, linkonce_t, strlen(linkonce_t)) == 0)
+    symname = aname + strlen(linkonce_t);
+  else
+    symname = strrchr(aname, '.') + 1;
+  std::string sig1(symname);
+  std::string sig2(aname);
+  Kept_section* kept1;
+  Kept_section* kept2;
+  bool include1 = alayout->find_or_add_kept_section(sig1, this, index, false,
+                                                   false, &kept1);
+  bool include2 = alayout->find_or_add_kept_section(sig2, this, index, false,
+                                                   true, &kept2);
+
+  if (!include2)
+    {
+      // We are not including this section because we already saw the
+      // name of the section as a signature.  This normally implies
+      // that the kept section is another linkonce section.  If it is
+      // the same size, record it as the section which corresponds to
+      // this one.
+      if (kept2->object() != NULL
+         && !kept2->is_comdat()
+         && kept2->linkonce_size() == sh_size)
+       this->set_kept_comdat_section(index, kept2->object(), kept2->shndx());
+    }
+  else if (!include1)
+    {
+      // The section is being discarded on the basis of its symbol
+      // name.  This means that the corresponding kept section was
+      // part of a comdat group, and it will be difficult to identify
+      // the specific section within that group that corresponds to
+      // this linkonce section.  We'll handle the simple case where
+      // the group has only one member section.  Otherwise, it's not
+      // worth the effort.
+      unsigned int kept_shndx;
+      uint64_t kept_size;
+      if (kept1->object() != NULL
+         && kept1->is_comdat()
+         && kept1->find_single_comdat_section(&kept_shndx, &kept_size)
+         && kept_size == sh_size)
+       this->set_kept_comdat_section(index, kept1->object(), kept_shndx);
+    }
   else
-    symname = strrchr(name, '.') + 1;
-  bool include1 = layout->add_comdat(symname, false);
-  bool include2 = layout->add_comdat(name, true);
+    {
+      kept1->set_linkonce_size(sh_size);
+      kept2->set_linkonce_size(sh_size);
+    }
+
   return include1 && include2;
 }
 
+// Layout an input section.
+
+template<int size, bool big_endian>
+inline void
+Sized_relobj<size, big_endian>::layout_section(Layout* alayout,
+                                               unsigned int shndx,
+                                               const char* aname,
+                                               typename This::Shdr& shdr,
+                                               unsigned int reloc_shndx,
+                                               unsigned int reloc_type)
+{
+  off_t aoffset;
+  Output_section* os = alayout->layout(this, shndx, aname, shdr,
+                                      reloc_shndx, reloc_type, &aoffset);
+
+  this->output_sections()[shndx] = os;
+  if (aoffset == -1)
+    this->section_offsets_[shndx] = invalid_address;
+  else
+    this->section_offsets_[shndx] = convert_types<Address, off_t>(aoffset);
+
+  // If this section requires special handling, and if there are
+  // relocs that apply to it, then we must do the special handling
+  // before we apply the relocs.
+  if (aoffset == -1 && reloc_shndx != 0)
+    this->set_relocs_must_follow_section_writes();
+}
+
 // Lay out the input sections.  We walk through the sections and check
 // whether they should be included in the link.  If they should, we
 // pass them to the Layout object, which will return an output section
-// and an offset.
+// and an offset.  
+// During garbage collection (--gc-sections) and identical code folding 
+// (--icf), this function is called twice.  When it is called the first 
+// time, it is for setting up some sections as roots to a work-list for
+// --gc-sections and to do comdat processing.  Actual layout happens the 
+// second time around after all the relevant sections have been determined.  
+// The first time, is_worklist_ready or is_icf_ready is false. It is then 
+// set to true after the garbage collection worklist or identical code 
+// folding is processed and the relevant sections to be kept are 
+// determined.  Then, this function is called again to layout the sections.
 
 template<int size, bool big_endian>
 void
 Sized_relobj<size, big_endian>::do_layout(Symbol_table* symtab,
-                                         Layout* layout,
+                                         Layout* alayout,
                                          Read_symbols_data* sd)
 {
-  const unsigned int shnum = this->shnum();
-  if (shnum == 0)
+  const unsigned int sec_shnum = this->shnum();
+  bool is_gc_pass_one = ((parameters->options().gc_sections() 
+                          && !symtab->gc()->is_worklist_ready())
+                         || (parameters->options().icf_enabled()
+                             && !symtab->icf()->is_icf_ready()));
+  bool is_gc_pass_two = ((parameters->options().gc_sections() 
+                          && symtab->gc()->is_worklist_ready())
+                         || (parameters->options().icf_enabled()
+                             && symtab->icf()->is_icf_ready()));
+
+  bool is_gc_or_icf = (parameters->options().gc_sections()
+                       || parameters->options().icf_enabled()); 
+
+  // Both is_gc_pass_one and is_gc_pass_two should not be true.
+  gold_assert(!(is_gc_pass_one  && is_gc_pass_two));
+
+  if (sec_shnum == 0)
     return;
+  Symbols_data* gc_sd = NULL;
+  if (is_gc_pass_one)
+    {
+      // During garbage collection save the symbols data to use it when 
+      // re-entering this function.   
+      gc_sd = new Symbols_data;
+      this->copy_symbols_data(gc_sd, sd, This::shdr_size * sec_shnum);
+      this->set_symbols_data(gc_sd);
+    }
+  else if (is_gc_pass_two)
+    {
+      gc_sd = this->get_symbols_data();
+    }
+
+  const unsigned char* section_headers_data = NULL;
+  section_size_type section_names_size;
+  const unsigned char* symbols_data = NULL;
+  section_size_type symbols_size;
+  section_offset_type external_symbols_offset;
+  const unsigned char* symbol_names_data = NULL;
+  section_size_type symbol_names_size;
+  if (is_gc_or_icf)
+    {
+      section_headers_data = gc_sd->section_headers_data;
+      section_names_size = gc_sd->section_names_size;
+      symbols_data = gc_sd->symbols_data;
+      symbols_size = gc_sd->symbols_size;
+      external_symbols_offset = gc_sd->external_symbols_offset;
+      symbol_names_data = gc_sd->symbol_names_data;
+      symbol_names_size = gc_sd->symbol_names_size;
+    }
+  else
+    {
+      section_headers_data = sd->section_headers->data();
+      section_names_size = sd->section_names_size;
+      if (sd->symbols != NULL)
+        symbols_data = sd->symbols->data();
+      symbols_size = sd->symbols_size;
+      external_symbols_offset = sd->external_symbols_offset;
+      if (sd->symbol_names != NULL)
+        symbol_names_data = sd->symbol_names->data();
+      symbol_names_size = sd->symbol_names_size;
+    }
 
   // Get the section headers.
-  const unsigned char* pshdrs = sd->section_headers->data();
+  const unsigned char* shdrs = section_headers_data;
+  const unsigned char* pshdrs;
 
   // Get the section names.
-  const unsigned char* pnamesu = sd->section_names->data();
+  const unsigned char* pnamesu = (is_gc_or_icf) 
+                                 ? gc_sd->section_names_data
+                                 : sd->section_names->data();
+
   const char* pnames = reinterpret_cast<const char*>(pnamesu);
 
+  // If any input files have been claimed by plugins, we need to defer
+  // actual layout until the replacement files have arrived.
+  const bool should_defer_layout =
+      (parameters->options().has_plugins()
+       && parameters->options().plugins()->should_defer_layout());
+  unsigned int num_sections_to_defer = 0;
+
   // For each section, record the index of the reloc section if any.
   // Use 0 to mean that there is no reloc section, -1U to mean that
   // there is more than one.
-  std::vector<unsigned int> reloc_shndx(shnum, 0);
-  std::vector<unsigned int> reloc_type(shnum, elfcpp::SHT_NULL);
+  std::vector<unsigned int> reloc_shndx(sec_shnum, 0);
+  std::vector<unsigned int> reloc_type(sec_shnum, elfcpp::SHT_NULL);
   // Skip the first, dummy, section.
-  pshdrs += This::shdr_size;
-  for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
+  pshdrs = shdrs + This::shdr_size;
+  for (unsigned int i = 1; i < sec_shnum; ++i, pshdrs += This::shdr_size)
     {
       typename This::Shdr shdr(pshdrs);
 
+      // Count the number of sections whose layout will be deferred.
+      if (should_defer_layout && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC))
+        ++num_sections_to_defer;
+
       unsigned int sh_type = shdr.get_sh_type();
       if (sh_type == elfcpp::SHT_REL || sh_type == elfcpp::SHT_RELA)
        {
-         unsigned int target_shndx = shdr.get_sh_info();
-         if (target_shndx == 0 || target_shndx >= shnum)
+         unsigned int target_shndx = this->adjust_shndx(shdr.get_sh_info());
+         if (target_shndx == 0 || target_shndx >= sec_shnum)
            {
              this->error(_("relocation section %u has bad info %u"),
                          i, target_shndx);
@@ -574,98 +1049,146 @@ Sized_relobj<size, big_endian>::do_layout(Symbol_table* symtab,
        }
     }
 
-  std::vector<Map_to_output>& map_sections(this->map_to_output());
-  map_sections.resize(shnum);
+  Output_sections& out_sections(this->output_sections());
+  std::vector<Address>& out_section_offsets(this->section_offsets_);
+
+  if (!is_gc_pass_two)
+    {
+      out_sections.resize(sec_shnum);
+      out_section_offsets.resize(sec_shnum);
+    }
 
   // If we are only linking for symbols, then there is nothing else to
   // do here.
   if (this->input_file()->just_symbols())
     {
-      delete sd->section_headers;
-      sd->section_headers = NULL;
-      delete sd->section_names;
-      sd->section_names = NULL;
+      if (!is_gc_pass_two)
+        {
+          delete sd->section_headers;
+          sd->section_headers = NULL;
+          delete sd->section_names;
+          sd->section_names = NULL;
+        }
       return;
     }
 
+  if (num_sections_to_defer > 0)
+    {
+      parameters->options().plugins()->add_deferred_layout_object(this);
+      this->deferred_layout_.reserve(num_sections_to_defer);
+    }
+
   // Whether we've seen a .note.GNU-stack section.
   bool seen_gnu_stack = false;
   // The flags of a .note.GNU-stack section.
   uint64_t gnu_stack_flags = 0;
 
   // Keep track of which sections to omit.
-  std::vector<bool> omit(shnum, false);
+  std::vector<bool> omit(sec_shnum, false);
 
   // Keep track of reloc sections when emitting relocations.
   const bool relocatable = parameters->options().relocatable();
-  const bool emit_relocs = (relocatable
-                           || parameters->options().emit_relocs());
+  const bool emit_rels = (relocatable
+                         || parameters->options().emit_relocs());
   std::vector<unsigned int> reloc_sections;
 
   // Keep track of .eh_frame sections.
   std::vector<unsigned int> eh_frame_sections;
 
   // Skip the first, dummy, section.
-  pshdrs = sd->section_headers->data() + This::shdr_size;
-  for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
+  pshdrs = shdrs + This::shdr_size;
+  for (unsigned int i = 1; i < sec_shnum; ++i, pshdrs += This::shdr_size)
     {
       typename This::Shdr shdr(pshdrs);
 
-      if (shdr.get_sh_name() >= sd->section_names_size)
+      if (shdr.get_sh_name() >= section_names_size)
        {
          this->error(_("bad section name offset for section %u: %lu"),
                      i, static_cast<unsigned long>(shdr.get_sh_name()));
          return;
        }
 
-      const char* name = pnames + shdr.get_sh_name();
+      const char* sname = pnames + shdr.get_sh_name();
 
-      if (this->handle_gnu_warning_section(name, i, symtab))
-       {
-         if (!relocatable)
-           omit[i] = true;
-       }
+      if (!is_gc_pass_two)
+        { 
+          if (this->handle_gnu_warning_section(sname, i, symtab))
+            { 
+             if (!relocatable)
+               omit[i] = true;
+           }
 
-      // The .note.GNU-stack section is special.  It gives the
-      // protection flags that this object file requires for the stack
-      // in memory.
-      if (strcmp(name, ".note.GNU-stack") == 0)
-       {
-         seen_gnu_stack = true;
-         gnu_stack_flags |= shdr.get_sh_flags();
-         omit[i] = true;
-       }
+          // The .note.GNU-stack section is special.  It gives the
+          // protection flags that this object file requires for the stack
+          // in memory.
+          if (strcmp(sname, ".note.GNU-stack") == 0)
+            {
+             seen_gnu_stack = true;
+             gnu_stack_flags |= shdr.get_sh_flags();
+             omit[i] = true;
+            }
 
-      bool discard = omit[i];
-      if (!discard)
-       {
-         if (shdr.get_sh_type() == elfcpp::SHT_GROUP)
+         // The .note.GNU-split-stack section is also special.  It
+         // indicates that the object was compiled with
+         // -fsplit-stack.
+         if (this->handle_split_stack_section(sname))
            {
-             if (!this->include_section_group(symtab, layout, i, name, shdr,
-                                              &omit))
-               discard = true;
+             if (!parameters->options().relocatable()
+                 && !parameters->options().shared())
+               omit[i] = true;
            }
-          else if ((shdr.get_sh_flags() & elfcpp::SHF_GROUP) == 0
-                   && Layout::is_linkonce(name))
+
+         // Skip attributes section.
+         if (parameters->target().is_attributes_section(sname))
            {
-             if (!this->include_linkonce_section(layout, name, shdr))
-               discard = true;
+             omit[i] = true;
            }
-       }
 
-      if (discard)
-       {
-         // Do not include this section in the link.
-         map_sections[i].output_section = NULL;
-         continue;
-       }
+          bool discard = omit[i];
+          if (!discard)
+            {
+             if (shdr.get_sh_type() == elfcpp::SHT_GROUP)
+               {
+                 if (!this->include_section_group(symtab, alayout, i, sname, 
+                                                   shdrs, pnames, 
+                                                   section_names_size,
+                                                  &omit))
+                   discard = true;
+               }
+              else if ((shdr.get_sh_flags() & elfcpp::SHF_GROUP) == 0
+                       && Layout::is_linkonce(sname))
+               {
+                 if (!this->include_linkonce_section(alayout, i, sname, shdr))
+                   discard = true;
+               }
+           }
+
+          if (discard)
+            {
+             // Do not include this section in the link.
+             out_sections[i] = NULL;
+              out_section_offsets[i] = invalid_address;
+             continue;
+            }
+        }
+      if (is_gc_pass_one && parameters->options().gc_sections())
+        {
+          if (is_section_name_included(sname)
+              || shdr.get_sh_type() == elfcpp::SHT_INIT_ARRAY 
+              || shdr.get_sh_type() == elfcpp::SHT_FINI_ARRAY)
+            {
+              symtab->gc()->worklist().push(Section_id(this, i)); 
+            }
+        }
 
       // When doing a relocatable link we are going to copy input
       // reloc sections into the output.  We only want to copy the
       // ones associated with sections which are not being discarded.
       // However, we don't know that yet for all sections.  So save
-      // reloc sections and process them later.
-      if (emit_relocs
+      // reloc sections and process them later. Garbage collection is
+      // not triggered when relocatable code is desired.
+      if (emit_rels
          && (shdr.get_sh_type() == elfcpp::SHT_REL
              || shdr.get_sh_type() == elfcpp::SHT_RELA))
        {
@@ -683,103 +1206,236 @@ Sized_relobj<size, big_endian>::do_layout(Symbol_table* symtab,
       // determine which sections are being discarded, and discard the
       // corresponding information.
       if (!relocatable
-         && strcmp(name, ".eh_frame") == 0
-         && this->check_eh_frame_flags(&shdr))
-       {
-         eh_frame_sections.push_back(i);
-         continue;
-       }
+          && strcmp(sname, ".eh_frame") == 0
+          && this->check_eh_frame_flags(&shdr))
+        {
+          if (is_gc_pass_one)
+            {
+              out_sections[i] = reinterpret_cast<Output_section*>(1);
+              out_section_offsets[i] = invalid_address;
+            }
+          else
+            eh_frame_sections.push_back(i);
+          continue;
+        }
+
+      if (is_gc_pass_two && parameters->options().gc_sections())
+        {
+          // This is executed during the second pass of garbage 
+          // collection. do_layout has been called before and some 
+          // sections have been already discarded. Simply ignore 
+          // such sections this time around.
+          if (out_sections[i] == NULL)
+            {
+              gold_assert(out_section_offsets[i] == invalid_address);
+              continue; 
+            }
+          if (((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0)
+              && symtab->gc()->is_section_garbage(this, i))
+              {
+                if (parameters->options().print_gc_sections())
+                  gold_info(_("%s: removing unused section from '%s'" 
+                              " in file '%s'"),
+                            program_name, this->section_name(i).c_str(), 
+                            this->name().c_str());
+                out_sections[i] = NULL;
+                out_section_offsets[i] = invalid_address;
+                continue;
+              }
+        }
 
-      off_t offset;
-      Output_section* os = layout->layout(this, i, name, shdr,
-                                         reloc_shndx[i], reloc_type[i],
-                                         &offset);
+      if (is_gc_pass_two && parameters->options().icf_enabled())
+        {
+          if (out_sections[i] == NULL)
+            {
+              gold_assert(out_section_offsets[i] == invalid_address);
+              continue;
+            }
+          if (((shdr.get_sh_flags() & elfcpp::SHF_ALLOC) != 0)
+              && symtab->icf()->is_section_folded(this, i))
+              {
+                if (parameters->options().print_icf_sections())
+                  {
+                    Section_id folded =
+                                symtab->icf()->get_folded_section(this, i);
+                    Relobj* folded_obj =
+                                reinterpret_cast<Relobj*>(folded.first);
+                    gold_info(_("%s: ICF folding section '%s' in file '%s'"
+                                "into '%s' in file '%s'"),
+                              program_name, this->section_name(i).c_str(),
+                              this->name().c_str(),
+                              folded_obj->section_name(folded.second).c_str(),
+                              folded_obj->name().c_str());
+                  }
+                out_sections[i] = NULL;
+                out_section_offsets[i] = invalid_address;
+                continue;
+              }
+        }
 
-      map_sections[i].output_section = os;
-      map_sections[i].offset = offset;
+      // Defer layout here if input files are claimed by plugins.  When gc
+      // is turned on this function is called twice.  For the second call
+      // should_defer_layout should be false.
+      if (should_defer_layout && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC))
+        {
+          gold_assert(!is_gc_pass_two);
+          this->deferred_layout_.push_back(Deferred_layout(i, sname, 
+                                                           pshdrs,
+                                                           reloc_shndx[i],
+                                                           reloc_type[i]));
+          // Put dummy values here; real values will be supplied by
+          // do_layout_deferred_sections.
+          out_sections[i] = reinterpret_cast<Output_section*>(2);
+          out_section_offsets[i] = invalid_address;
+          continue;
+        }
 
-      // If this section requires special handling, and if there are
-      // relocs that apply to it, then we must do the special handling
-      // before we apply the relocs.
-      if (offset == -1 && reloc_shndx[i] != 0)
-       this->set_relocs_must_follow_section_writes();
+      // During gc_pass_two if a section that was previously deferred is
+      // found, do not layout the section as layout_deferred_sections will
+      // do it later from gold.cc.
+      if (is_gc_pass_two 
+          && (out_sections[i] == reinterpret_cast<Output_section*>(2)))
+        continue;
+
+      if (is_gc_pass_one)
+        {
+          // This is during garbage collection. The out_sections are 
+          // assigned in the second call to this function. 
+          out_sections[i] = reinterpret_cast<Output_section*>(1);
+          out_section_offsets[i] = invalid_address;
+        }
+      else
+        {
+          // When garbage collection is switched on the actual layout
+          // only happens in the second call.
+          this->layout_section(alayout, i, sname, shdr, reloc_shndx[i],
+                               reloc_type[i]);
+        }
     }
 
-  layout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags);
+  if (!is_gc_pass_one)
+    alayout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags);
 
   // When doing a relocatable link handle the reloc sections at the
-  // end.
-  if (emit_relocs)
+  // end.  Garbage collection  and Identical Code Folding is not 
+  // turned on for relocatable code. 
+  if (emit_rels)
     this->size_relocatable_relocs();
+
+  gold_assert(!(is_gc_or_icf) || reloc_sections.empty());
+
   for (std::vector<unsigned int>::const_iterator p = reloc_sections.begin();
        p != reloc_sections.end();
        ++p)
     {
       unsigned int i = *p;
       const unsigned char* pshdr;
-      pshdr = sd->section_headers->data() + i * This::shdr_size;
+      pshdr = section_headers_data + i * This::shdr_size;
       typename This::Shdr shdr(pshdr);
 
-      unsigned int data_shndx = shdr.get_sh_info();
-      if (data_shndx >= shnum)
+      unsigned int data_shndx = this->adjust_shndx(shdr.get_sh_info());
+      if (data_shndx >= sec_shnum)
        {
          // We already warned about this above.
          continue;
        }
 
-      Output_section* data_section = map_sections[data_shndx].output_section;
+      Output_section* data_section = out_sections[data_shndx];
       if (data_section == NULL)
        {
-         map_sections[i].output_section = NULL;
+         out_sections[i] = NULL;
+          out_section_offsets[i] = invalid_address;
          continue;
        }
 
       Relocatable_relocs* rr = new Relocatable_relocs();
       this->set_relocatable_relocs(i, rr);
 
-      Output_section* os = layout->layout_reloc(this, i, shdr, data_section,
-                                               rr);
-      map_sections[i].output_section = os;
-      map_sections[i].offset = -1;
+      Output_section* os = alayout->layout_reloc(this, i, shdr, data_section,
+                                                rr);
+      out_sections[i] = os;
+      out_section_offsets[i] = invalid_address;
     }
 
   // Handle the .eh_frame sections at the end.
+  gold_assert(!is_gc_pass_one || eh_frame_sections.empty());
   for (std::vector<unsigned int>::const_iterator p = eh_frame_sections.begin();
        p != eh_frame_sections.end();
        ++p)
     {
       gold_assert(this->has_eh_frame_);
-      gold_assert(sd->external_symbols_offset != 0);
+      gold_assert(external_symbols_offset != 0);
 
       unsigned int i = *p;
       const unsigned char *pshdr;
-      pshdr = sd->section_headers->data() + i * This::shdr_size;
+      pshdr = section_headers_data + i * This::shdr_size;
       typename This::Shdr shdr(pshdr);
 
-      off_t offset;
-      Output_section* os = layout->layout_eh_frame(this,
-                                                  sd->symbols->data(),
-                                                  sd->symbols_size,
-                                                  sd->symbol_names->data(),
-                                                  sd->symbol_names_size,
-                                                  i, shdr,
-                                                  reloc_shndx[i],
-                                                  reloc_type[i],
-                                                  &offset);
-      map_sections[i].output_section = os;
-      map_sections[i].offset = offset;
+      off_t off;
+      Output_section* os = alayout->layout_eh_frame(this,
+                                                   symbols_data,
+                                                   symbols_size,
+                                                   symbol_names_data,
+                                                   symbol_names_size,
+                                                   i, shdr,
+                                                   reloc_shndx[i],
+                                                   reloc_type[i],
+                                                   &off);
+      out_sections[i] = os;
+      if (off == -1)
+       {
+         // An object can contain at most one section holding exception
+         // frame information.
+         gold_assert(this->discarded_eh_frame_shndx_ == -1U);
+         this->discarded_eh_frame_shndx_ = i;
+         out_section_offsets[i] = invalid_address;
+       }
+      else
+        out_section_offsets[i] = convert_types<Address, off_t>(off);
 
       // If this section requires special handling, and if there are
       // relocs that apply to it, then we must do the special handling
       // before we apply the relocs.
-      if (offset == -1 && reloc_shndx[i] != 0)
+      if (off == -1 && reloc_shndx[i] != 0)
        this->set_relocs_must_follow_section_writes();
     }
 
-  delete sd->section_headers;
-  sd->section_headers = NULL;
-  delete sd->section_names;
-  sd->section_names = NULL;
+  if (is_gc_pass_two)
+    {
+      delete[] gc_sd->section_headers_data;
+      delete[] gc_sd->section_names_data;
+      delete[] gc_sd->symbols_data;
+      delete[] gc_sd->symbol_names_data;
+      this->set_symbols_data(NULL);
+    }
+  else
+    {
+      delete sd->section_headers;
+      sd->section_headers = NULL;
+      delete sd->section_names;
+      sd->section_names = NULL;
+    }
+}
+
+// Layout sections whose layout was deferred while waiting for
+// input files from a plugin.
+
+template<int size, bool big_endian>
+void
+Sized_relobj<size, big_endian>::do_layout_deferred_sections(Layout* alayout)
+{
+  typename std::vector<Deferred_layout>::iterator deferred;
+
+  for (deferred = this->deferred_layout_.begin();
+       deferred != this->deferred_layout_.end();
+       ++deferred)
+    {
+      typename This::Shdr shdr(deferred->shdr_data_);
+      this->layout_section(alayout, deferred->shndx_, deferred->name_.c_str(),
+                           shdr, deferred->reloc_shndx_, deferred->reloc_type_);
+    }
+
+  this->deferred_layout_.clear();
 }
 
 // Add the symbols to the symbol table.
@@ -787,7 +1443,8 @@ Sized_relobj<size, big_endian>::do_layout(Symbol_table* symtab,
 template<int size, bool big_endian>
 void
 Sized_relobj<size, big_endian>::do_add_symbols(Symbol_table* symtab,
-                                              Read_symbols_data* sd)
+                                              Read_symbols_data* sd,
+                                              Layout*)
 {
   if (sd->symbols == NULL)
     {
@@ -795,10 +1452,10 @@ Sized_relobj<size, big_endian>::do_add_symbols(Symbol_table* symtab,
       return;
     }
 
-  const int sym_size = This::sym_size;
+  const int symsize = This::sym_size;
   size_t symcount = ((sd->symbols_size - sd->external_symbols_offset)
-                    / sym_size);
-  if (symcount * sym_size != sd->symbols_size - sd->external_symbols_offset)
+                    / symsize);
+  if (symcount * symsize != sd->symbols_size - sd->external_symbols_offset)
     {
       this->error(_("size of symbols is not multiple of symbol size"));
       return;
@@ -810,8 +1467,10 @@ Sized_relobj<size, big_endian>::do_add_symbols(Symbol_table* symtab,
     reinterpret_cast<const char*>(sd->symbol_names->data());
   symtab->add_from_relobj(this,
                          sd->symbols->data() + sd->external_symbols_offset,
-                         symcount, sym_names, sd->symbol_names_size,
-                         &this->symbols_);
+                         symcount, this->local_symbol_count_,
+                         sym_names, sd->symbol_names_size,
+                         &this->symbols_,
+                         &this->defined_count_);
 
   delete sd->symbols;
   sd->symbols = NULL;
@@ -838,21 +1497,22 @@ Sized_relobj<size, big_endian>::do_count_local_symbols(Stringpool* pool,
     }
 
   // Read the symbol table section header.
-  const unsigned int symtab_shndx = this->symtab_shndx_;
+  const unsigned int sym_tab_shndx = this->symtab_shndx_;
   typename This::Shdr symtabshdr(this,
-                                this->elf_file_.section_header(symtab_shndx));
+                                this->elf_file_.section_header(sym_tab_shndx));
   gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
 
   // Read the local symbols.
-  const int sym_size = This::sym_size;
+  const int symsize = This::sym_size;
   const unsigned int loccount = this->local_symbol_count_;
   gold_assert(loccount == symtabshdr.get_sh_info());
-  off_t locsize = loccount * sym_size;
+  off_t locsize = loccount * symsize;
   const unsigned char* psyms = this->get_view(symtabshdr.get_sh_offset(),
-                                             locsize, true);
+                                             locsize, true, true);
 
   // Read the symbol names.
-  const unsigned int strtab_shndx = symtabshdr.get_sh_link();
+  const unsigned int strtab_shndx =
+    this->adjust_shndx(symtabshdr.get_sh_link());
   section_size_type strtab_size;
   const unsigned char* pnamesu = this->section_contents(strtab_shndx,
                                                        &strtab_size,
@@ -861,20 +1521,23 @@ Sized_relobj<size, big_endian>::do_count_local_symbols(Stringpool* pool,
 
   // Loop over the local symbols.
 
-  const std::vector<Map_to_output>& mo(this->map_to_output());
-  unsigned int shnum = this->shnum();
+  const Output_sections& out_sections(this->output_sections());
+  unsigned int sec_shnum = this->shnum();
   unsigned int count = 0;
   unsigned int dyncount = 0;
   // Skip the first, dummy, symbol.
-  psyms += sym_size;
-  for (unsigned int i = 1; i < loccount; ++i, psyms += sym_size)
+  psyms += symsize;
+  bool discard_locals = parameters->options().discard_locals();
+  for (unsigned int i = 1; i < loccount; ++i, psyms += symsize)
     {
       elfcpp::Sym<size, big_endian> sym(psyms);
 
       Symbol_value<size>& lv(this->local_values_[i]);
 
-      unsigned int shndx = sym.get_st_shndx();
-      lv.set_input_shndx(shndx);
+      bool is_ordinary;
+      unsigned int shndx = this->adjust_sym_shndx(i, sym.get_st_shndx(),
+                                                 &is_ordinary);
+      lv.set_input_shndx(shndx, is_ordinary);
 
       if (sym.get_st_type() == elfcpp::STT_SECTION)
        lv.set_is_section_symbol();
@@ -886,7 +1549,8 @@ Sized_relobj<size, big_endian>::do_count_local_symbols(Stringpool* pool,
 
       // Decide whether this symbol should go into the output file.
 
-      if (shndx < shnum && mo[shndx].output_section == NULL)
+      if ((shndx < sec_shnum && out_sections[shndx] == NULL)
+         || (shndx == this->discarded_eh_frame_shndx_))
         {
          lv.set_no_output_symtab_entry();
           gold_assert(!lv.needs_output_dynsym_entry());
@@ -909,15 +1573,44 @@ Sized_relobj<size, big_endian>::do_count_local_symbols(Stringpool* pool,
          continue;
        }
 
+      // If --discard-locals option is used, discard all temporary local
+      // symbols.  These symbols start with system-specific local label
+      // prefixes, typically .L for ELF system.  We want to be compatible
+      // with GNU ld so here we essentially use the same check in
+      // bfd_is_local_label().  The code is different because we already
+      // know that:
+      //
+      //   - the symbol is local and thus cannot have global or weak binding.
+      //   - the symbol is not a section symbol.
+      //   - the symbol has a name.
+      //
+      // We do not discard a symbol if it needs a dynamic symbol entry.
+      const char* sname = pnames + sym.get_st_name();
+      if (discard_locals
+         && sym.get_st_type() != elfcpp::STT_FILE
+         && !lv.needs_output_dynsym_entry()
+         && parameters->target().is_local_label_name(sname))
+       {
+         lv.set_no_output_symtab_entry();
+         continue;
+       }
+
+      // Discard the local symbol if -retain_symbols_file is specified
+      // and the local symbol is not in that file.
+      if (!parameters->options().should_retain_symbol(sname))
+        {
+          lv.set_no_output_symtab_entry();
+          continue;
+        }
+
       // Add the symbol to the symbol table string pool.
-      const char* name = pnames + sym.get_st_name();
-      pool->add(name, true, NULL);
+      pool->add(sname, true, NULL);
       ++count;
 
       // If needed, add the symbol to the dynamic symbol table string pool.
       if (lv.needs_output_dynsym_entry())
         {
-          dynpool->add(name, true, NULL);
+          dynpool->add(sname, true, NULL);
           ++dyncount;
         }
     }
@@ -934,31 +1627,34 @@ Sized_relobj<size, big_endian>::do_count_local_symbols(Stringpool* pool,
 template<int size, bool big_endian>
 unsigned int
 Sized_relobj<size, big_endian>::do_finalize_local_symbols(unsigned int index,
-                                                          off_t off)
+                                                         off_t off,
+                                                          Symbol_table* symtab)
 {
   gold_assert(off == static_cast<off_t>(align_address(off, size >> 3)));
 
   const unsigned int loccount = this->local_symbol_count_;
   this->local_symbol_offset_ = off;
 
-  const std::vector<Map_to_output>& mo(this->map_to_output());
-  unsigned int shnum = this->shnum();
+  const bool relocatable = parameters->options().relocatable();
+  const Output_sections& out_sections(this->output_sections());
+  const std::vector<Address>& out_offsets(this->section_offsets_);
+  unsigned int sec_shnum = this->shnum();
 
   for (unsigned int i = 1; i < loccount; ++i)
     {
       Symbol_value<size>& lv(this->local_values_[i]);
 
-      unsigned int shndx = lv.input_shndx();
+      bool is_ordinary;
+      unsigned int shndx = lv.input_shndx(&is_ordinary);
 
       // Set the output symbol value.
-      
-      if (shndx >= elfcpp::SHN_LORESERVE)
+
+      if (!is_ordinary)
        {
-         if (shndx == elfcpp::SHN_ABS || shndx == elfcpp::SHN_COMMON)
+         if (shndx == elfcpp::SHN_ABS || Symbol::is_common_shndx(shndx))
            lv.set_output_value(lv.input_value());
          else
            {
-             // FIXME: Handle SHN_XINDEX.
              this->error(_("unknown section index %u for local symbol %u"),
                          shndx, i);
              lv.set_output_value(0);
@@ -966,36 +1662,79 @@ Sized_relobj<size, big_endian>::do_finalize_local_symbols(unsigned int index,
        }
       else
        {
-         if (shndx >= shnum)
+         if (shndx >= sec_shnum)
            {
              this->error(_("local symbol %u section index %u out of range"),
                          i, shndx);
              shndx = 0;
            }
 
-         Output_section* os = mo[shndx].output_section;
+         Output_section* os = out_sections[shndx];
+          Address secoffset = out_offsets[shndx];
+          if (symtab->is_section_folded(this, shndx))
+            {
+              gold_assert (os == NULL && secoffset == invalid_address);
+              // Get the os of the section it is folded onto.
+              Section_id folded = symtab->icf()->get_folded_section(this,
+                                                                    shndx);
+              gold_assert(folded.first != NULL);
+              Sized_relobj<size, big_endian>* folded_obj = reinterpret_cast
+                <Sized_relobj<size, big_endian>*>(folded.first);
+              os = folded_obj->output_section(folded.second);
+              gold_assert(os != NULL);
+              secoffset = folded_obj->get_output_section_offset(folded.second);
+              gold_assert(secoffset != invalid_address);
+            }
 
          if (os == NULL)
            {
-             lv.set_output_value(0);
+              // This local symbol belongs to a section we are discarding.
+              // In some cases when applying relocations later, we will
+              // attempt to match it to the corresponding kept section,
+              // so we leave the input value unchanged here.
              continue;
            }
-         else if (mo[shndx].offset == -1)
+         else if (secoffset == invalid_address)
            {
+             uint64_t start;
+
              // This is a SHF_MERGE section or one which otherwise
-             // requires special handling.  We get the output address
-             // of the start of the merged section.  If this is not a
-             // section symbol, we can then determine the final
-             // value.  If it is a section symbol, we can not, as in
-             // that case we have to consider the addend to determine
-             // the value to use in a relocation.
-             if (!lv.is_section_symbol())
-               lv.set_output_value(os->output_address(this, shndx,
-                                                       lv.input_value()));
+             // requires special handling.
+             if (shndx == this->discarded_eh_frame_shndx_)
+               {
+                 // This local symbol belongs to a discarded .eh_frame
+                 // section.  Just treat it like the case in which
+                 // os == NULL above.
+                 gold_assert(this->has_eh_frame_);
+                 continue;
+               }
+             else if (!lv.is_section_symbol())
+               {
+                 // This is not a section symbol.  We can determine
+                 // the final value now.
+                 lv.set_output_value(os->output_address(this, shndx,
+                                                        lv.input_value()));
+               }
+             else if (!os->find_starting_output_address(this, shndx, &start))
+               {
+                 // This is a section symbol, but apparently not one in a
+                 // merged section.  First check to see if this is a relaxed
+                 // input section.  If so, use its address.  Otherwise just
+                 // use the start of the output section.  This happens with
+                 // relocatable links when the input object has section
+                 // symbols for arbitrary non-merge sections.
+                 const Output_section_data* posd =
+                   os->find_relaxed_input_section(this, shndx);
+                 if (posd != NULL)
+                   lv.set_output_value(posd->address());
+                 else
+                   lv.set_output_value(os->address());
+               }
              else
                {
-                  section_offset_type start =
-                    os->starting_output_address(this, shndx);
+                 // We have to consider the addend to determine the
+                 // value to use in a relocation.  START is the start
+                 // of this input section.
                  Merged_symbol_value<size>* msv =
                    new Merged_symbol_value<size>(lv.input_value(), start);
                  lv.set_merged_symbol_value(msv);
@@ -1003,11 +1742,11 @@ Sized_relobj<size, big_endian>::do_finalize_local_symbols(unsigned int index,
            }
           else if (lv.is_tls_symbol())
            lv.set_output_value(os->tls_offset()
-                               + mo[shndx].offset
+                               + secoffset
                                + lv.input_value());
          else
-           lv.set_output_value(os->address()
-                               + mo[shndx].offset
+           lv.set_output_value((relocatable ? 0 : os->address())
+                               + secoffset
                                + lv.input_value());
        }
 
@@ -1052,17 +1791,42 @@ Sized_relobj<size, big_endian>::do_set_local_dynsym_offset(off_t off)
   return this->output_local_dynsym_count_;
 }
 
-// Return the value of the local symbol symndx.
+// If Symbols_data is not NULL get the section flags from here otherwise
+// get it from the file.
+
+template<int size, bool big_endian>
+uint64_t
+Sized_relobj<size, big_endian>::do_section_flags(unsigned int shndx)
+{
+  Symbols_data* sd = this->get_symbols_data();
+  if (sd != NULL)
+    {
+      const unsigned char* pshdrs = sd->section_headers_data
+                                    + This::shdr_size * shndx;
+      typename This::Shdr shdr(pshdrs);
+      return shdr.get_sh_flags(); 
+    }
+  // If sd is NULL, read the section header from the file.
+  return this->elf_file_.section_flags(shndx); 
+}
+
+// Get the section's ent size from Symbols_data.  Called by get_section_contents
+// in icf.cc
+
 template<int size, bool big_endian>
-typename elfcpp::Elf_types<size>::Elf_Addr
-Sized_relobj<size, big_endian>::local_symbol_value(unsigned int symndx) const
+uint64_t
+Sized_relobj<size, big_endian>::do_section_entsize(unsigned int shndx)
 {
-  gold_assert(symndx < this->local_symbol_count_);
-  gold_assert(symndx < this->local_values_.size());
-  const Symbol_value<size>& lv(this->local_values_[symndx]);
-  return lv.value(this, 0);
+  Symbols_data* sd = this->get_symbols_data();
+  gold_assert (sd != NULL);
+
+  const unsigned char* pshdrs = sd->section_headers_data
+                                + This::shdr_size * shndx;
+  typename This::Shdr shdr(pshdrs);
+  return shdr.get_sh_entsize(); 
 }
 
+
 // Write out the local symbols.
 
 template<int size, bool big_endian>
@@ -1070,11 +1834,17 @@ void
 Sized_relobj<size, big_endian>::write_local_symbols(
     Output_file* of,
     const Stringpool* sympool,
-    const Stringpool* dynpool)
+    const Stringpool* dynpool,
+    Output_symtab_xindex* symtab_xindex,
+    Output_symtab_xindex* dynsym_xindex)
 {
-  if (parameters->options().strip_all()
-      && this->output_local_dynsym_count_ == 0)
-    return;
+  const bool strip_all = parameters->options().strip_all();
+  if (strip_all)
+    {
+      if (this->output_local_dynsym_count_ == 0)
+       return;
+      this->output_local_symbol_count_ = 0;
+    }
 
   gold_assert(this->symtab_shndx_ != -1U);
   if (this->symtab_shndx_ == 0)
@@ -1084,21 +1854,22 @@ Sized_relobj<size, big_endian>::write_local_symbols(
     }
 
   // Read the symbol table section header.
-  const unsigned int symtab_shndx = this->symtab_shndx_;
+  const unsigned int sym_tab_shndx = this->symtab_shndx_;
   typename This::Shdr symtabshdr(this,
-                                this->elf_file_.section_header(symtab_shndx));
+                                this->elf_file_.section_header(sym_tab_shndx));
   gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
   const unsigned int loccount = this->local_symbol_count_;
   gold_assert(loccount == symtabshdr.get_sh_info());
 
   // Read the local symbols.
-  const int sym_size = This::sym_size;
-  off_t locsize = loccount * sym_size;
+  const int symsize = This::sym_size;
+  off_t locsize = loccount * symsize;
   const unsigned char* psyms = this->get_view(symtabshdr.get_sh_offset(),
-                                             locsize, false);
+                                             locsize, true, false);
 
   // Read the symbol names.
-  const unsigned int strtab_shndx = symtabshdr.get_sh_link();
+  const unsigned int strtab_shndx =
+    this->adjust_shndx(symtabshdr.get_sh_link());
   section_size_type strtab_size;
   const unsigned char* pnamesu = this->section_contents(strtab_shndx,
                                                        &strtab_size,
@@ -1107,71 +1878,82 @@ Sized_relobj<size, big_endian>::write_local_symbols(
 
   // Get views into the output file for the portions of the symbol table
   // and the dynamic symbol table that we will be writing.
-  off_t output_size = this->output_local_symbol_count_ * sym_size;
+  off_t output_size = this->output_local_symbol_count_ * symsize;
   unsigned char* oview = NULL;
   if (output_size > 0)
     oview = of->get_output_view(this->local_symbol_offset_, output_size);
 
-  off_t dyn_output_size = this->output_local_dynsym_count_ * sym_size;
+  off_t dyn_output_size = this->output_local_dynsym_count_ * symsize;
   unsigned char* dyn_oview = NULL;
   if (dyn_output_size > 0)
     dyn_oview = of->get_output_view(this->local_dynsym_offset_,
                                     dyn_output_size);
 
-  const std::vector<Map_to_output>& mo(this->map_to_output());
+  const Output_sections out_sections(this->output_sections());
 
   gold_assert(this->local_values_.size() == loccount);
 
   unsigned char* ov = oview;
   unsigned char* dyn_ov = dyn_oview;
-  psyms += sym_size;
-  for (unsigned int i = 1; i < loccount; ++i, psyms += sym_size)
+  psyms += symsize;
+  for (unsigned int i = 1; i < loccount; ++i, psyms += symsize)
     {
       elfcpp::Sym<size, big_endian> isym(psyms);
 
-      unsigned int st_shndx = isym.get_st_shndx();
-      if (st_shndx < elfcpp::SHN_LORESERVE)
+      Symbol_value<size>& lv(this->local_values_[i]);
+
+      bool is_ordinary;
+      unsigned int st_shndx = this->adjust_sym_shndx(i, isym.get_st_shndx(),
+                                                    &is_ordinary);
+      if (is_ordinary)
        {
-         gold_assert(st_shndx < mo.size());
-         if (mo[st_shndx].output_section == NULL)
+         gold_assert(st_shndx < out_sections.size());
+         if (out_sections[st_shndx] == NULL)
            continue;
-         st_shndx = mo[st_shndx].output_section->out_shndx();
+         st_shndx = out_sections[st_shndx]->out_shndx();
+         if (st_shndx >= elfcpp::SHN_LORESERVE)
+           {
+             if (lv.needs_output_symtab_entry() && !strip_all)
+               symtab_xindex->add(lv.output_symtab_index(), st_shndx);
+             if (lv.needs_output_dynsym_entry())
+               dynsym_xindex->add(lv.output_dynsym_index(), st_shndx);
+             st_shndx = elfcpp::SHN_XINDEX;
+           }
        }
 
       // Write the symbol to the output symbol table.
-      if (!parameters->options().strip_all()
-         && this->local_values_[i].needs_output_symtab_entry())
+      if (!strip_all && lv.needs_output_symtab_entry())
         {
           elfcpp::Sym_write<size, big_endian> osym(ov);
 
           gold_assert(isym.get_st_name() < strtab_size);
-          const char* name = pnames + isym.get_st_name();
-          osym.put_st_name(sympool->get_offset(name));
+          const char* sname = pnames + isym.get_st_name();
+          osym.put_st_name(sympool->get_offset(sname));
           osym.put_st_value(this->local_values_[i].value(this, 0));
           osym.put_st_size(isym.get_st_size());
           osym.put_st_info(isym.get_st_info());
           osym.put_st_other(isym.get_st_other());
           osym.put_st_shndx(st_shndx);
 
-          ov += sym_size;
+          ov += symsize;
         }
 
       // Write the symbol to the output dynamic symbol table.
-      if (this->local_values_[i].needs_output_dynsym_entry())
+      if (lv.needs_output_dynsym_entry())
         {
           gold_assert(dyn_ov < dyn_oview + dyn_output_size);
           elfcpp::Sym_write<size, big_endian> osym(dyn_ov);
 
           gold_assert(isym.get_st_name() < strtab_size);
-          const char* name = pnames + isym.get_st_name();
-          osym.put_st_name(dynpool->get_offset(name));
+          const char* sname = pnames + isym.get_st_name();
+          osym.put_st_name(dynpool->get_offset(sname));
           osym.put_st_value(this->local_values_[i].value(this, 0));
           osym.put_st_size(isym.get_st_size());
           osym.put_st_info(isym.get_st_info());
           osym.put_st_other(isym.get_st_other());
           osym.put_st_shndx(st_shndx);
 
-          dyn_ov += sym_size;
+          dyn_ov += symsize;
         }
     }
 
@@ -1198,7 +1980,7 @@ template<int size, bool big_endian>
 bool
 Sized_relobj<size, big_endian>::get_symbol_location_info(
     unsigned int shndx,
-    off_t offset,
+    off_t sym_offset,
     Symbol_location_info* info)
 {
   if (this->symtab_shndx_ == 0)
@@ -1209,17 +1991,18 @@ Sized_relobj<size, big_endian>::get_symbol_location_info(
                                                        &symbols_size,
                                                        false);
 
-  unsigned int symbol_names_shndx = this->section_link(this->symtab_shndx_);
+  unsigned int symbol_names_shndx =
+    this->adjust_shndx(this->section_link(this->symtab_shndx_));
   section_size_type names_size;
   const unsigned char* symbol_names_u =
     this->section_contents(symbol_names_shndx, &names_size, false);
   const char* symbol_names = reinterpret_cast<const char*>(symbol_names_u);
 
-  const int sym_size = This::sym_size;
-  const size_t count = symbols_size / sym_size;
+  const int symsize = This::sym_size;
+  const size_t count = symbols_size / symsize;
 
   const unsigned char* p = symbols;
-  for (size_t i = 0; i < count; ++i, p += sym_size)
+  for (size_t i = 0; i < count; ++i, p += symsize)
     {
       elfcpp::Sym<size, big_endian> sym(p);
 
@@ -1229,18 +2012,24 @@ Sized_relobj<size, big_endian>::get_symbol_location_info(
            info->source_file = "(invalid)";
          else
            info->source_file = symbol_names + sym.get_st_name();
+         continue;
        }
-      else if (sym.get_st_shndx() == shndx
-               && static_cast<off_t>(sym.get_st_value()) <= offset
-               && (static_cast<off_t>(sym.get_st_value() + sym.get_st_size())
-                   > offset))
+
+      bool is_ordinary;
+      unsigned int st_shndx = this->adjust_sym_shndx(i, sym.get_st_shndx(),
+                                                    &is_ordinary);
+      if (is_ordinary
+         && st_shndx == shndx
+         && static_cast<off_t>(sym.get_st_value()) <= sym_offset
+         && (static_cast<off_t>(sym.get_st_value() + sym.get_st_size())
+             > sym_offset))
         {
           if (sym.get_st_name() > names_size)
            info->enclosing_symbol_name = "(invalid)";
          else
             {
               info->enclosing_symbol_name = symbol_names + sym.get_st_name();
-              if (parameters->options().demangle())
+              if (parameters->options().do_demangle())
                 {
                   char* demangled_name = cplus_demangle(
                       info->enclosing_symbol_name.c_str(),
@@ -1259,6 +2048,56 @@ Sized_relobj<size, big_endian>::get_symbol_location_info(
   return false;
 }
 
+// Look for a kept section corresponding to the given discarded section,
+// and return its output address.  This is used only for relocations in
+// debugging sections.  If we can't find the kept section, return 0.
+
+template<int size, bool big_endian>
+typename Sized_relobj<size, big_endian>::Address
+Sized_relobj<size, big_endian>::map_to_kept_section(
+    unsigned int shndx,
+    bool* found) const
+{
+  Relobj* kept_object;
+  unsigned int kept_shndx;
+  if (this->get_kept_comdat_section(shndx, &kept_object, &kept_shndx))
+    {
+      Sized_relobj<size, big_endian>* kept_relobj =
+       static_cast<Sized_relobj<size, big_endian>*>(kept_object);
+      Output_section* os = kept_relobj->output_section(kept_shndx);
+      Address addr_offset = kept_relobj->get_output_section_offset(kept_shndx);
+      if (os != NULL && addr_offset != invalid_address)
+       {
+         *found = true;
+         return os->address() + addr_offset;
+       }
+    }
+  *found = false;
+  return 0;
+}
+
+// Get symbol counts.
+
+template<int size, bool big_endian>
+void
+Sized_relobj<size, big_endian>::do_get_global_symbol_counts(
+    const Symbol_table*,
+    size_t* defined,
+    size_t* used) const
+{
+  *defined = this->defined_count_;
+  size_t count = 0;
+  for (Symbols::const_iterator p = this->symbols_.begin();
+       p != this->symbols_.end();
+       ++p)
+    if (*p != NULL
+       && (*p)->source() == Symbol::FROM_OBJECT
+       && (*p)->object() == this
+       && (*p)->is_defined())
+      ++count;
+  *used = count;
+}
+
 // Input_objects methods.
 
 // Add a regular relocatable object to the list.  Return false if this
@@ -1267,15 +2106,9 @@ Sized_relobj<size, big_endian>::get_symbol_location_info(
 bool
 Input_objects::add_object(Object* obj)
 {
-  // Set the global target from the first object file we recognize.
-  Target* target = obj->target();
-  if (!parameters->target_valid())
-    set_parameters_target(target);
-  else if (target != &parameters->target())
-    {
-      obj->error(_("incompatible target"));
-      return false;
-    }
+  // Print the filename if the -t/--trace option is selected.
+  if (parameters->options().trace())
+    gold_info("%s", obj->name().c_str());
 
   if (!obj->is_dynamic())
     this->relobj_list_.push_back(static_cast<Relobj*>(obj));
@@ -1294,35 +2127,19 @@ Input_objects::add_object(Object* obj)
        }
 
       this->dynobj_list_.push_back(dynobj);
+    }
 
-      // If this is -lc, remember the directory in which we found it.
-      // We use this when issuing warnings about undefined symbols: as
-      // a heuristic, we don't warn about system libraries found in
-      // the same directory as -lc.
-      if (strncmp(soname, "libc.so", 7) == 0)
-       {
-         const char* object_name = dynobj->name().c_str();
-         const char* base = lbasename(object_name);
-         if (base != object_name)
-           this->system_library_directory_.assign(object_name,
-                                                  base - 1 - object_name);
-       }
+  // Add this object to the cross-referencer if requested.
+  if (parameters->options().user_set_print_symbol_counts())
+    {
+      if (this->cref_ == NULL)
+       this->cref_ = new Cref();
+      this->cref_->add_object(obj);
     }
 
   return true;
 }
 
-// Return whether an object was found in the system library directory.
-
-bool
-Input_objects::found_in_system_library_directory(const Object* object) const
-{
-  return (!this->system_library_directory_.empty()
-         && object->name().compare(0,
-                                   this->system_library_directory_.size(),
-                                   this->system_library_directory_) == 0);
-}
-
 // For each dynamic object, record whether we've seen all of its
 // explicit dependencies.
 
@@ -1349,6 +2166,38 @@ Input_objects::check_dynamic_dependencies() const
     }
 }
 
+// Start processing an archive.
+
+void
+Input_objects::archive_start(Archive* archive)
+{
+  if (parameters->options().user_set_print_symbol_counts())
+    {
+      if (this->cref_ == NULL)
+       this->cref_ = new Cref();
+      this->cref_->add_archive_start(archive);
+    }
+}
+
+// Stop processing an archive.
+
+void
+Input_objects::archive_stop(Archive* archive)
+{
+  if (parameters->options().user_set_print_symbol_counts())
+    this->cref_->add_archive_stop(archive);
+}
+
+// Print symbol counts
+
+void
+Input_objects::print_symbol_counts(const Symbol_table* symtab) const
+{
+  if (parameters->options().user_set_print_symbol_counts()
+      && this->cref_ != NULL)
+    this->cref_->print_symbol_counts(symtab);
+}
+
 // Relocate_info methods.
 
 // Return a string describing the location of a relocation.  This is
@@ -1407,29 +2256,29 @@ using namespace gold;
 template<int size, bool big_endian>
 Object*
 make_elf_sized_object(const std::string& name, Input_file* input_file,
-                     off_t offset, const elfcpp::Ehdr<size, big_endian>& ehdr)
+                     off_t offset, const elfcpp::Ehdr<size, big_endian>& ehdr,
+                     bool* punconfigured)
 {
-  int et = ehdr.get_e_type();
-  if (et == elfcpp::ET_REL)
-    {
-      Sized_relobj<size, big_endian>* obj =
-       new Sized_relobj<size, big_endian>(name, input_file, offset, ehdr);
-      obj->setup(ehdr);
-      return obj;
-    }
-  else if (et == elfcpp::ET_DYN)
-    {
-      Sized_dynobj<size, big_endian>* obj =
-       new Sized_dynobj<size, big_endian>(name, input_file, offset, ehdr);
-      obj->setup(ehdr);
-      return obj;
-    }
-  else
+  Target* target = select_target(ehdr.get_e_machine(), size, big_endian,
+                                ehdr.get_e_ident()[elfcpp::EI_OSABI],
+                                ehdr.get_e_ident()[elfcpp::EI_ABIVERSION]);
+  if (target == NULL)
+    gold_fatal(_("%s: unsupported ELF machine number %d"),
+              name.c_str(), ehdr.get_e_machine());
+
+  if (!parameters->target_valid())
+    set_parameters_target(target);
+  else if (target != &parameters->target())
     {
-      gold_error(_("%s: unsupported ELF file type %d"),
-                name.c_str(), et);
+      if (punconfigured != NULL)
+       *punconfigured = true;
+      else
+       gold_error(_("%s: incompatible target"), name.c_str());
       return NULL;
     }
+
+  return target->make_elf_object<size, big_endian>(name, input_file, offset,
+                                                  ehdr);
 }
 
 } // End anonymous namespace.
@@ -1437,73 +2286,60 @@ make_elf_sized_object(const std::string& name, Input_file* input_file,
 namespace gold
 {
 
-// Read an ELF file and return the appropriate instance of Object.
+// Return whether INPUT_FILE is an ELF object.
 
-Object*
-make_elf_object(const std::string& name, Input_file* input_file, off_t offset,
-               const unsigned char* p, section_offset_type bytes)
+bool
+is_elf_object(Input_file* input_file, off_t offset,
+             const unsigned char** start, int *read_size)
 {
-  if (bytes < elfcpp::EI_NIDENT)
-    {
-      gold_error(_("%s: ELF file too short"), name.c_str());
-      return NULL;
-    }
+  off_t filesize = input_file->file().filesize();
+  int want = elfcpp::Elf_recognizer::max_header_size;
+  if (filesize - offset < want)
+    want = filesize - offset;
 
-  int v = p[elfcpp::EI_VERSION];
-  if (v != elfcpp::EV_CURRENT)
-    {
-      if (v == elfcpp::EV_NONE)
-       gold_error(_("%s: invalid ELF version 0"), name.c_str());
-      else
-       gold_error(_("%s: unsupported ELF version %d"), name.c_str(), v);
-      return NULL;
-    }
+  const unsigned char* p = input_file->file().get_view(offset, 0, want,
+                                                      true, false);
+  *start = p;
+  *read_size = want;
 
-  int c = p[elfcpp::EI_CLASS];
-  if (c == elfcpp::ELFCLASSNONE)
-    {
-      gold_error(_("%s: invalid ELF class 0"), name.c_str());
-      return NULL;
-    }
-  else if (c != elfcpp::ELFCLASS32
-          && c != elfcpp::ELFCLASS64)
-    {
-      gold_error(_("%s: unsupported ELF class %d"), name.c_str(), c);
-      return NULL;
-    }
+  return elfcpp::Elf_recognizer::is_elf_file(p, want);
+}
 
-  int d = p[elfcpp::EI_DATA];
-  if (d == elfcpp::ELFDATANONE)
-    {
-      gold_error(_("%s: invalid ELF data encoding"), name.c_str());
-      return NULL;
-    }
-  else if (d != elfcpp::ELFDATA2LSB
-          && d != elfcpp::ELFDATA2MSB)
+// Read an ELF file and return the appropriate instance of Object.
+
+Object*
+make_elf_object(const std::string& name, Input_file* input_file, off_t offset,
+               const unsigned char* p, section_offset_type bytes,
+               bool* punconfigured)
+{
+  if (punconfigured != NULL)
+    *punconfigured = false;
+
+  std::string error;
+  bool big_endian = false;
+  int size = 0;
+  if (!elfcpp::Elf_recognizer::is_valid_header(p, bytes, &size,
+                                               &big_endian, &error))
     {
-      gold_error(_("%s: unsupported ELF data encoding %d"), name.c_str(), d);
+      gold_error(_("%s: %s"), name.c_str(), error.c_str());
       return NULL;
     }
 
-  bool big_endian = d == elfcpp::ELFDATA2MSB;
-
-  if (c == elfcpp::ELFCLASS32)
+  if (size == 32)
     {
-      if (bytes < elfcpp::Elf_sizes<32>::ehdr_size)
-       {
-         gold_error(_("%s: ELF file too short"), name.c_str());
-         return NULL;
-       }
       if (big_endian)
        {
 #ifdef HAVE_TARGET_32_BIG
          elfcpp::Ehdr<32, true> ehdr(p);
          return make_elf_sized_object<32, true>(name, input_file,
-                                                offset, ehdr);
+                                                offset, ehdr, punconfigured);
 #else
-          gold_error(_("%s: not configured to support "
-                      "32-bit big-endian object"),
-                    name.c_str());
+         if (punconfigured != NULL)
+           *punconfigured = true;
+         else
+           gold_error(_("%s: not configured to support "
+                        "32-bit big-endian object"),
+                      name.c_str());
          return NULL;
 #endif
        }
@@ -1512,32 +2348,33 @@ make_elf_object(const std::string& name, Input_file* input_file, off_t offset,
 #ifdef HAVE_TARGET_32_LITTLE
          elfcpp::Ehdr<32, false> ehdr(p);
          return make_elf_sized_object<32, false>(name, input_file,
-                                                 offset, ehdr);
+                                                 offset, ehdr, punconfigured);
 #else
-          gold_error(_("%s: not configured to support "
-                      "32-bit little-endian object"),
-                    name.c_str());
+         if (punconfigured != NULL)
+           *punconfigured = true;
+         else
+           gold_error(_("%s: not configured to support "
+                        "32-bit little-endian object"),
+                      name.c_str());
          return NULL;
 #endif
        }
     }
-  else
+  else if (size == 64)
     {
-      if (bytes < elfcpp::Elf_sizes<32>::ehdr_size)
-       {
-         gold_error(_("%s: ELF file too short"), name.c_str());
-         return NULL;
-       }
       if (big_endian)
        {
 #ifdef HAVE_TARGET_64_BIG
          elfcpp::Ehdr<64, true> ehdr(p);
          return make_elf_sized_object<64, true>(name, input_file,
-                                                offset, ehdr);
+                                                offset, ehdr, punconfigured);
 #else
-          gold_error(_("%s: not configured to support "
-                      "64-bit big-endian object"),
-                    name.c_str());
+         if (punconfigured != NULL)
+           *punconfigured = true;
+         else
+           gold_error(_("%s: not configured to support "
+                        "64-bit big-endian object"),
+                      name.c_str());
          return NULL;
 #endif
        }
@@ -1546,19 +2383,51 @@ make_elf_object(const std::string& name, Input_file* input_file, off_t offset,
 #ifdef HAVE_TARGET_64_LITTLE
          elfcpp::Ehdr<64, false> ehdr(p);
          return make_elf_sized_object<64, false>(name, input_file,
-                                                 offset, ehdr);
+                                                 offset, ehdr, punconfigured);
 #else
-          gold_error(_("%s: not configured to support "
-                      "64-bit little-endian object"),
-                    name.c_str());
+         if (punconfigured != NULL)
+           *punconfigured = true;
+         else
+           gold_error(_("%s: not configured to support "
+                        "64-bit little-endian object"),
+                      name.c_str());
          return NULL;
 #endif
        }
     }
+  else
+    gold_unreachable();
 }
 
-// Instantiate the templates we need.  We could use the configure
-// script to restrict this to only the ones for implemented targets.
+// Instantiate the templates we need.
+
+#ifdef HAVE_TARGET_32_LITTLE
+template
+void
+Object::read_section_data<32, false>(elfcpp::Elf_file<32, false, Object>*,
+                                    Read_symbols_data*);
+#endif
+
+#ifdef HAVE_TARGET_32_BIG
+template
+void
+Object::read_section_data<32, true>(elfcpp::Elf_file<32, true, Object>*,
+                                   Read_symbols_data*);
+#endif
+
+#ifdef HAVE_TARGET_64_LITTLE
+template
+void
+Object::read_section_data<64, false>(elfcpp::Elf_file<64, false, Object>*,
+                                    Read_symbols_data*);
+#endif
+
+#ifdef HAVE_TARGET_64_BIG
+template
+void
+Object::read_section_data<64, true>(elfcpp::Elf_file<64, true, Object>*,
+                                   Read_symbols_data*);
+#endif
 
 #ifdef HAVE_TARGET_32_LITTLE
 template
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