gdb: add target_ops::supports_displaced_step
[deliverable/binutils-gdb.git] / gold / object.cc
index b14c85db87afee9e02de5932c74b470ec5977299..c486a2011d5c4d5167272ca83d93cd20f90bbf3d 100644 (file)
@@ -1,6 +1,6 @@
 // object.cc -- support for an object file for linking in gold
 
-// Copyright 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
+// Copyright (C) 2006-2020 Free Software Foundation, Inc.
 // Written by Ian Lance Taylor <iant@google.com>.
 
 // This file is part of gold.
 #include "plugin.h"
 #include "compressed_output.h"
 #include "incremental.h"
+#include "merge.h"
 
 namespace gold
 {
 
 // Struct Read_symbols_data.
 
-// Destroy any remaining File_view objects.
+// Destroy any remaining File_view objects and buffers of decompressed
+// sections.
 
 Read_symbols_data::~Read_symbols_data()
 {
@@ -178,16 +180,7 @@ Object::error(const char* format, ...) const
 const unsigned char*
 Object::section_contents(unsigned int shndx, section_size_type* plen,
                         bool cache)
-{
-  Location loc(this->do_section_contents(shndx));
-  *plen = convert_to_section_size_type(loc.data_size);
-  if (*plen == 0)
-    {
-      static const unsigned char empty[1] = { '\0' };
-      return empty;
-    }
-  return this->get_view(loc.file_offset, *plen, true, cache);
-}
+{ return this->do_section_contents(shndx, plen, cache); }
 
 // Read the section data into SD.  This is code common to Sized_relobj_file
 // and Sized_dynobj, so we put it into Object.
@@ -276,29 +269,66 @@ Object::handle_split_stack_section(const char* name)
 
 // Class Relobj
 
+template<int size>
+void
+Relobj::initialize_input_to_output_map(unsigned int shndx,
+         typename elfcpp::Elf_types<size>::Elf_Addr starting_address,
+         Unordered_map<section_offset_type,
+         typename elfcpp::Elf_types<size>::Elf_Addr>* output_addresses) const {
+  Object_merge_map *map = this->object_merge_map_;
+  map->initialize_input_to_output_map<size>(shndx, starting_address,
+                                           output_addresses);
+}
+
+void
+Relobj::add_merge_mapping(Output_section_data *output_data,
+                          unsigned int shndx, section_offset_type offset,
+                          section_size_type length,
+                          section_offset_type output_offset) {
+  Object_merge_map* object_merge_map = this->get_or_create_merge_map();
+  object_merge_map->add_mapping(output_data, shndx, offset, length, output_offset);
+}
+
+bool
+Relobj::merge_output_offset(unsigned int shndx, section_offset_type offset,
+                            section_offset_type *poutput) const {
+  Object_merge_map* object_merge_map = this->object_merge_map_;
+  if (object_merge_map == NULL)
+    return false;
+  return object_merge_map->get_output_offset(shndx, offset, poutput);
+}
+
+const Output_section_data*
+Relobj::find_merge_section(unsigned int shndx) const {
+  Object_merge_map* object_merge_map = this->object_merge_map_;
+  if (object_merge_map == NULL)
+    return NULL;
+  return object_merge_map->find_merge_section(shndx);
+}
+
 // 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 
+// 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)
+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)];
+  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];
+        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);
+        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];
+      gc_sd->symbols_data =
+            new unsigned char[sd->symbols_size];
       memcpy(gc_sd->symbols_data, sd->symbols->data(),
-            sd->symbols_size);
+           sd->symbols_size);
     }
   else
     {
@@ -309,9 +339,9 @@ Relobj::copy_symbols_data(Symbols_data* gc_sd, Read_symbols_data* sd,
   if (sd->symbol_names != NULL)
     {
       gc_sd->symbol_names_data =
-             new unsigned char[sd->symbol_names_size];
+            new unsigned char[sd->symbol_names_size];
       memcpy(gc_sd->symbol_names_data, sd->symbol_names->data(),
-            sd->symbol_names_size);
+           sd->symbol_names_size);
     }
   else
     {
@@ -327,22 +357,26 @@ Relobj::copy_symbols_data(Symbols_data* gc_sd, Read_symbols_data* sd,
 bool
 Relobj::is_section_name_included(const char* name)
 {
-  if (is_prefix_of(".ctors", name) 
-      || is_prefix_of(".dtors", name) 
-      || is_prefix_of(".note", name) 
-      || is_prefix_of(".init", name) 
-      || is_prefix_of(".fini", name) 
-      || is_prefix_of(".gcc_except_table", name) 
-      || is_prefix_of(".jcr", name) 
-      || is_prefix_of(".preinit_array", name) 
-      || (is_prefix_of(".text", name) 
-          && strstr(name, "personality")) 
-      || (is_prefix_of(".data", name) 
-          &&  strstr(name, "personality")) 
+  if (is_prefix_of(".ctors", name)
+      || is_prefix_of(".dtors", name)
+      || is_prefix_of(".note", name)
+      || is_prefix_of(".init", name)
+      || is_prefix_of(".fini", name)
+      || is_prefix_of(".gcc_except_table", name)
+      || is_prefix_of(".jcr", name)
+      || is_prefix_of(".preinit_array", name)
+      || (is_prefix_of(".text", name)
+         && strstr(name, "personality"))
+      || (is_prefix_of(".data", name)
+         && strstr(name, "personality"))
+      || (is_prefix_of(".sdata", name)
+         && strstr(name, "personality"))
       || (is_prefix_of(".gnu.linkonce.d", name)
-         && strstr(name, "personality")))
+         && strstr(name, "personality"))
+      || (is_prefix_of(".rodata", name)
+         && strstr(name, "nptl_version")))
     {
-      return true; 
+      return true;
     }
   return false;
 }
@@ -372,6 +406,14 @@ Relobj::finalize_incremental_relocs(Layout* layout, bool clear_counts)
   layout->incremental_inputs()->set_reloc_count(rindex);
 }
 
+Object_merge_map*
+Relobj::get_or_create_merge_map()
+{
+  if (!this->object_merge_map_)
+    this->object_merge_map_ = new Object_merge_map();
+  return this->object_merge_map_;
+}
+
 // Class Sized_relobj.
 
 // Iterate over local symbols, calling a visitor class V for each GOT offset
@@ -385,7 +427,8 @@ Sized_relobj<size, big_endian>::do_for_all_local_got_entries(
   unsigned int nsyms = this->local_symbol_count();
   for (unsigned int i = 0; i < nsyms; i++)
     {
-      Local_got_offsets::const_iterator p = this->local_got_offsets_.find(i);
+      Local_got_entry_key key(i, 0);
+      Local_got_offsets::const_iterator p = this->local_got_offsets_.find(key);
       if (p != this->local_got_offsets_.end())
        {
          const Got_offset_list* got_offsets = p->second;
@@ -394,6 +437,23 @@ Sized_relobj<size, big_endian>::do_for_all_local_got_entries(
     }
 }
 
+// Get the address of an output section.
+
+template<int size, bool big_endian>
+uint64_t
+Sized_relobj<size, big_endian>::do_output_section_address(
+    unsigned int shndx)
+{
+  // If the input file is linked as --just-symbols, the output
+  // section address is the input section address.
+  if (this->just_symbols())
+    return this->section_address(shndx);
+
+  const Output_section* os = this->do_output_section(shndx);
+  gold_assert(os != NULL);
+  return os->address();
+}
+
 // Class Sized_relobj_file.
 
 template<int size, bool big_endian>
@@ -416,11 +476,12 @@ Sized_relobj_file<size, big_endian>::Sized_relobj_file(
     local_plt_offsets_(),
     kept_comdat_sections_(),
     has_eh_frame_(false),
-    discarded_eh_frame_shndx_(-1U),
+    is_deferred_layout_(false),
     deferred_layout_(),
     deferred_layout_relocs_(),
-    compressed_sections_()
+    output_views_(NULL)
 {
+  this->e_type_ = ehdr.get_e_type();
 }
 
 template<int size, bool big_endian>
@@ -511,10 +572,71 @@ bool
 Sized_relobj_file<size, big_endian>::check_eh_frame_flags(
     const elfcpp::Shdr<size, big_endian>* shdr) const
 {
-  return (shdr->get_sh_type() == elfcpp::SHT_PROGBITS
+  elfcpp::Elf_Word sh_type = shdr->get_sh_type();
+  return ((sh_type == elfcpp::SHT_PROGBITS
+          || sh_type == parameters->target().unwind_section_type())
          && (shdr->get_sh_flags() & elfcpp::SHF_ALLOC) != 0);
 }
 
+// Find the section header with the given name.
+
+template<int size, bool big_endian>
+const unsigned char*
+Object::find_shdr(
+    const unsigned char* pshdrs,
+    const char* name,
+    const char* names,
+    section_size_type names_size,
+    const unsigned char* hdr) const
+{
+  const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
+  const unsigned int shnum = this->shnum();
+  const unsigned char* hdr_end = pshdrs + shdr_size * shnum;
+  size_t sh_name = 0;
+
+  while (1)
+    {
+      if (hdr)
+       {
+         // We found HDR last time we were called, continue looking.
+         typename elfcpp::Shdr<size, big_endian> shdr(hdr);
+         sh_name = shdr.get_sh_name();
+       }
+      else
+       {
+         // Look for the next occurrence of NAME in NAMES.
+         // The fact that .shstrtab produced by current GNU tools is
+         // string merged means we shouldn't have both .not.foo and
+         // .foo in .shstrtab, and multiple .foo sections should all
+         // have the same sh_name.  However, this is not guaranteed
+         // by the ELF spec and not all ELF object file producers may
+         // be so clever.
+         size_t len = strlen(name) + 1;
+         const char *p = sh_name ? names + sh_name + len : names;
+         p = reinterpret_cast<const char*>(memmem(p, names_size - (p - names),
+                                                  name, len));
+         if (p == NULL)
+           return NULL;
+         sh_name = p - names;
+         hdr = pshdrs;
+         if (sh_name == 0)
+           return hdr;
+       }
+
+      hdr += shdr_size;
+      while (hdr < hdr_end)
+       {
+         typename elfcpp::Shdr<size, big_endian> shdr(hdr);
+         if (shdr.get_sh_name() == sh_name)
+           return hdr;
+         hdr += shdr_size;
+       }
+      hdr = NULL;
+      if (sh_name == 0)
+       return hdr;
+    }
+}
+
 // Return whether there is a GNU .eh_frame section, given the section
 // headers and the section names.
 
@@ -525,30 +647,70 @@ Sized_relobj_file<size, big_endian>::find_eh_frame(
     const char* names,
     section_size_type names_size) const
 {
-  const unsigned int shnum = this->shnum();
-  const unsigned char* p = pshdrs + This::shdr_size;
-  for (unsigned int i = 1; i < shnum; ++i, p += This::shdr_size)
+  const unsigned char* s = NULL;
+
+  while (1)
     {
-      typename This::Shdr shdr(p);
+      s = this->template find_shdr<size, big_endian>(pshdrs, ".eh_frame",
+                                                    names, names_size, s);
+      if (s == NULL)
+       return false;
+
+      typename This::Shdr shdr(s);
       if (this->check_eh_frame_flags(&shdr))
-       {
-         if (shdr.get_sh_name() >= names_size)
-           {
-             this->error(_("bad section name offset for section %u: %lu"),
-                         i, static_cast<unsigned long>(shdr.get_sh_name()));
-             continue;
-           }
+       return true;
+    }
+}
 
-         const char* name = names + shdr.get_sh_name();
-         if (strcmp(name, ".eh_frame") == 0)
-           return true;
-       }
+// Return TRUE if this is a section whose contents will be needed in the
+// Add_symbols task.  This function is only called for sections that have
+// already passed the test in is_compressed_debug_section() and the debug
+// section name prefix, ".debug"/".zdebug", has been skipped.
+
+static bool
+need_decompressed_section(const char* name)
+{
+  if (*name++ != '_')
+    return false;
+
+#ifdef ENABLE_THREADS
+  // Decompressing these sections now will help only if we're
+  // multithreaded.
+  if (parameters->options().threads())
+    {
+      // We will need .zdebug_str if this is not an incremental link
+      // (i.e., we are processing string merge sections) or if we need
+      // to build a gdb index.
+      if ((!parameters->incremental() || parameters->options().gdb_index())
+         && strcmp(name, "str") == 0)
+       return true;
+
+      // We will need these other sections when building a gdb index.
+      if (parameters->options().gdb_index()
+         && (strcmp(name, "info") == 0
+             || strcmp(name, "types") == 0
+             || strcmp(name, "pubnames") == 0
+             || strcmp(name, "pubtypes") == 0
+             || strcmp(name, "ranges") == 0
+             || strcmp(name, "abbrev") == 0))
+       return true;
     }
+#endif
+
+  // Even when single-threaded, we will need .zdebug_str if this is
+  // not an incremental link and we are building a gdb index.
+  // Otherwise, we would decompress the section twice: once for
+  // string merge processing, and once for building the gdb index.
+  if (!parameters->incremental()
+      && parameters->options().gdb_index()
+      && strcmp(name, "str") == 0)
+    return true;
+
   return false;
 }
 
 // Build a table for any compressed debug sections, mapping each section index
-// to the uncompressed size.
+// to the uncompressed size and (if needed) the decompressed contents.
 
 template<int size, bool big_endian>
 Compressed_section_map*
@@ -557,11 +719,13 @@ build_compressed_section_map(
     unsigned int shnum,
     const char* names,
     section_size_type names_size,
-    Sized_relobj_file<size, big_endian>* obj)
+    Object* obj,
+    bool decompress_if_needed)
 {
-  Compressed_section_map* uncompressed_sizes = new Compressed_section_map();
+  Compressed_section_map* uncompressed_map = new Compressed_section_map();
   const unsigned int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
   const unsigned char* p = pshdrs + shdr_size;
+
   for (unsigned int i = 1; i < shnum; ++i, p += shdr_size)
     {
       typename elfcpp::Shdr<size, big_endian> shdr(p);
@@ -576,19 +740,86 @@ build_compressed_section_map(
            }
 
          const char* name = names + shdr.get_sh_name();
-         if (is_compressed_debug_section(name))
+         bool is_compressed = ((shdr.get_sh_flags()
+                                & elfcpp::SHF_COMPRESSED) != 0);
+         bool is_zcompressed = (!is_compressed
+                                && is_compressed_debug_section(name));
+
+         if (is_zcompressed || is_compressed)
            {
              section_size_type len;
              const unsigned char* contents =
                  obj->section_contents(i, &len, false);
-             uint64_t uncompressed_size = get_uncompressed_size(contents, len);
+             uint64_t uncompressed_size;
+             Compressed_section_info info;
+             if (is_zcompressed)
+               {
+                 // Skip over the ".zdebug" prefix.
+                 name += 7;
+                 uncompressed_size = get_uncompressed_size(contents, len);
+                 info.addralign = shdr.get_sh_addralign();
+               }
+             else
+               {
+                 // Skip over the ".debug" prefix.
+                 name += 6;
+                 elfcpp::Chdr<size, big_endian> chdr(contents);
+                 uncompressed_size = chdr.get_ch_size();
+                 info.addralign = chdr.get_ch_addralign();
+               }
+             info.size = convert_to_section_size_type(uncompressed_size);
+             info.flag = shdr.get_sh_flags();
+             info.contents = NULL;
              if (uncompressed_size != -1ULL)
-               (*uncompressed_sizes)[i] =
-                   convert_to_section_size_type(uncompressed_size);
+               {
+                 unsigned char* uncompressed_data = NULL;
+                 if (decompress_if_needed && need_decompressed_section(name))
+                   {
+                     uncompressed_data = new unsigned char[uncompressed_size];
+                     if (decompress_input_section(contents, len,
+                                                  uncompressed_data,
+                                                  uncompressed_size,
+                                                  size, big_endian,
+                                                  shdr.get_sh_flags()))
+                       info.contents = uncompressed_data;
+                     else
+                       delete[] uncompressed_data;
+                   }
+                 (*uncompressed_map)[i] = info;
+               }
            }
        }
     }
-  return uncompressed_sizes;
+  return uncompressed_map;
+}
+
+// Stash away info for a number of special sections.
+// Return true if any of the sections found require local symbols to be read.
+
+template<int size, bool big_endian>
+bool
+Sized_relobj_file<size, big_endian>::do_find_special_sections(
+    Read_symbols_data* sd)
+{
+  const unsigned char* const pshdrs = sd->section_headers->data();
+  const unsigned char* namesu = sd->section_names->data();
+  const char* names = reinterpret_cast<const char*>(namesu);
+
+  if (this->find_eh_frame(pshdrs, names, sd->section_names_size))
+    this->has_eh_frame_ = true;
+
+  Compressed_section_map* compressed_sections =
+    build_compressed_section_map<size, big_endian>(
+      pshdrs, this->shnum(), names, sd->section_names_size, this, true);
+  if (compressed_sections != NULL)
+    this->set_compressed_sections(compressed_sections);
+
+  return (this->has_eh_frame_
+         || (!parameters->options().relocatable()
+             && parameters->options().gdb_index()
+             && (memmem(names, sd->section_names_size, "debug_info", 11) != NULL
+                 || memmem(names, sd->section_names_size,
+                           "debug_types", 12) != NULL)));
 }
 
 // Read the sections and symbols from an object file.
@@ -596,6 +827,16 @@ build_compressed_section_map(
 template<int size, bool big_endian>
 void
 Sized_relobj_file<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
+{
+  this->base_read_symbols(sd);
+}
+
+// Read the sections and symbols from an object file.  This is common
+// code for all target-specific overrides of do_read_symbols().
+
+template<int size, bool big_endian>
+void
+Sized_relobj_file<size, big_endian>::base_read_symbols(Read_symbols_data* sd)
 {
   this->read_section_data(&this->elf_file_, sd);
 
@@ -603,17 +844,7 @@ Sized_relobj_file<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
 
   this->find_symtab(pshdrs);
 
-  const unsigned char* namesu = sd->section_names->data();
-  const char* names = reinterpret_cast<const char*>(namesu);
-  if (memmem(names, sd->section_names_size, ".eh_frame", 10) != NULL)
-    {
-      if (this->find_eh_frame(pshdrs, names, sd->section_names_size))
-        this->has_eh_frame_ = true;
-    }
-  if (memmem(names, sd->section_names_size, ".zdebug_", 8) != NULL)
-    this->compressed_sections_ =
-        build_compressed_section_map(pshdrs, this->shnum(), names,
-                                    sd->section_names_size, this);
+  bool need_local_symbols = this->do_find_special_sections(sd);
 
   sd->symbols = NULL;
   sd->symbols_size = 0;
@@ -632,7 +863,8 @@ Sized_relobj_file<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
                                 + this->symtab_shndx_ * This::shdr_size);
   gold_assert(symtabshdr.get_sh_type() == elfcpp::SHT_SYMTAB);
 
-  // If this object has a .eh_frame section, we need all the symbols.
+  // If this object has a .eh_frame section, or if building a .gdb_index
+  // section and there is debug info, we need all the symbols.
   // Otherwise we only need the external symbols.  While it would be
   // simpler to just always read all the symbols, I've seen object
   // files with well over 2000 local symbols, which for a 64-bit
@@ -650,8 +882,8 @@ Sized_relobj_file<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
   off_t extoff = dataoff + locsize;
   section_size_type extsize = datasize - locsize;
 
-  off_t readoff = this->has_eh_frame_ ? dataoff : extoff;
-  section_size_type readsize = this->has_eh_frame_ ? datasize : extsize;
+  off_t readoff = need_local_symbols ? dataoff : extoff;
+  section_size_type readsize = need_local_symbols ? datasize : extsize;
 
   if (readsize == 0)
     {
@@ -683,7 +915,7 @@ Sized_relobj_file<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
 
   sd->symbols = fvsymtab;
   sd->symbols_size = readsize;
-  sd->external_symbols_offset = this->has_eh_frame_ ? locsize : 0;
+  sd->external_symbols_offset = need_local_symbols ? locsize : 0;
   sd->symbol_names = fvstrtab;
   sd->symbol_names_size =
     convert_to_section_size_type(strtabshdr.get_sh_size());
@@ -746,10 +978,11 @@ Sized_relobj_file<size, big_endian>::include_section_group(
   // just like ordinary sections.
   elfcpp::Elf_Word flags = elfcpp::Swap<32, big_endian>::readval(pword);
 
-  // Look up the group signature, which is the name of a symbol.  This
-  // is a lot of effort to go to to read a string.  Why didn't they
-  // just have the group signature point into the string table, rather
-  // than indirect through a symbol?
+  // Look up the group signature, which is the name of a symbol.  ELF
+  // uses a symbol name because some group signatures are long, and
+  // the name is generally already in the symbol table, so it makes
+  // sense to put the long string just once in .strtab rather than in
+  // both .strtab and .shstrtab.
 
   // Get the appropriate symbol table header (this will normally be
   // the single SHT_SYMTAB section, but in principle it need not be).
@@ -803,7 +1036,7 @@ Sized_relobj_file<size, big_endian>::include_section_group(
        }
       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();
+       signature = section_names + member_shdr.get_sh_name();
     }
 
   // Record this section group in the layout, and see whether we've already
@@ -857,18 +1090,18 @@ Sized_relobj_file<size, big_endian>::include_section_group(
       // 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);
+       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;
-        }
+       {
+         // 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)
@@ -878,46 +1111,21 @@ Sized_relobj_file<size, big_endian>::include_section_group(
                                             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());
-               }
-            }
-        }
+       {
+         (*omit)[shndx] = true;
+
+         // Store a mapping from this section to the Kept_section
+         // information for the group.  This mapping is used for
+         // relocation processing and diagnostics.
+         // If the kept section is a linkonce section, we don't
+         // bother with it unless the comdat group contains just
+         // a single section, making it easy to match up.
+         if (is_comdat
+             && (kept_section->is_comdat() || count == 2))
+           this->set_kept_comdat_section(shndx, true, symndx,
+                                         member_shdr.get_sh_size(),
+                                         kept_section);
+       }
     }
 
   if (relocate_group)
@@ -981,10 +1189,8 @@ Sized_relobj_file<size, big_endian>::include_linkonce_section(
       // 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());
+      if (kept2->object() != NULL && !kept2->is_comdat())
+       this->set_kept_comdat_section(index, false, 0, sh_size, kept2);
     }
   else if (!include1)
     {
@@ -995,13 +1201,8 @@ Sized_relobj_file<size, big_endian>::include_linkonce_section(
       // 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);
+      if (kept1->object() != NULL && kept1->is_comdat())
+       this->set_kept_comdat_section(index, false, 0, sh_size, kept1);
     }
   else
     {
@@ -1016,16 +1217,18 @@ Sized_relobj_file<size, big_endian>::include_linkonce_section(
 
 template<int size, bool big_endian>
 inline void
-Sized_relobj_file<size, big_endian>::layout_section(Layout* layout,
-                                                   unsigned int shndx,
-                                                   const char* name,
-                                                   typename This::Shdr& shdr,
-                                                   unsigned int reloc_shndx,
-                                                   unsigned int reloc_type)
+Sized_relobj_file<size, big_endian>::layout_section(
+    Layout* layout,
+    unsigned int shndx,
+    const char* name,
+    const typename This::Shdr& shdr,
+    unsigned int sh_type,
+    unsigned int reloc_shndx,
+    unsigned int reloc_type)
 {
   off_t offset;
-  Output_section* os = layout->layout(this, shndx, name, shdr,
-                                         reloc_shndx, reloc_type, &offset);
+  Output_section* os = layout->layout(this, shndx, name, shdr, sh_type,
+                                     reloc_shndx, reloc_type, &offset);
 
   this->output_sections()[shndx] = os;
   if (offset == -1)
@@ -1040,19 +1243,172 @@ Sized_relobj_file<size, big_endian>::layout_section(Layout* layout,
     this->set_relocs_must_follow_section_writes();
 }
 
+// Layout an input .eh_frame section.
+
+template<int size, bool big_endian>
+void
+Sized_relobj_file<size, big_endian>::layout_eh_frame_section(
+    Layout* layout,
+    const unsigned char* symbols_data,
+    section_size_type symbols_size,
+    const unsigned char* symbol_names_data,
+    section_size_type symbol_names_size,
+    unsigned int shndx,
+    const typename This::Shdr& shdr,
+    unsigned int reloc_shndx,
+    unsigned int reloc_type)
+{
+  gold_assert(this->has_eh_frame_);
+
+  off_t offset;
+  Output_section* os = layout->layout_eh_frame(this,
+                                              symbols_data,
+                                              symbols_size,
+                                              symbol_names_data,
+                                              symbol_names_size,
+                                              shndx,
+                                              shdr,
+                                              reloc_shndx,
+                                              reloc_type,
+                                              &offset);
+  this->output_sections()[shndx] = os;
+  if (os == NULL || offset == -1)
+    this->section_offsets()[shndx] = invalid_address;
+  else
+    this->section_offsets()[shndx] = convert_types<Address, off_t>(offset);
+
+  // If this section requires special handling, and if there are
+  // relocs that aply to it, then we must do the special handling
+  // before we apply the relocs.
+  if (os != NULL && offset == -1 && reloc_shndx != 0)
+    this->set_relocs_must_follow_section_writes();
+}
+
+// Layout an input .note.gnu.property section.
+
+// This note section has an *extremely* non-standard layout.
+// The gABI spec says that ELF-64 files should have 8-byte fields and
+// 8-byte alignment in the note section, but the Gnu tools generally
+// use 4-byte fields and 4-byte alignment (see the comment for
+// Layout::create_note).  This section uses 4-byte fields (i.e.,
+// namesz, descsz, and type are always 4 bytes), the name field is
+// padded to a multiple of 4 bytes, but the desc field is padded
+// to a multiple of 4 or 8 bytes, depending on the ELF class.
+// The individual properties within the desc field always use
+// 4-byte pr_type and pr_datasz fields, but pr_data is padded to
+// a multiple of 4 or 8 bytes, depending on the ELF class.
+
+template<int size, bool big_endian>
+void
+Sized_relobj_file<size, big_endian>::layout_gnu_property_section(
+    Layout* layout,
+    unsigned int shndx)
+{
+  section_size_type contents_len;
+  const unsigned char* pcontents = this->section_contents(shndx,
+                                                         &contents_len,
+                                                         false);
+  const unsigned char* pcontents_end = pcontents + contents_len;
+
+  // Loop over all the notes in this section.
+  while (pcontents < pcontents_end)
+    {
+      if (pcontents + 16 > pcontents_end)
+       {
+         gold_warning(_("%s: corrupt .note.gnu.property section "
+                        "(note too short)"),
+                      this->name().c_str());
+         return;
+       }
+
+      size_t namesz = elfcpp::Swap<32, big_endian>::readval(pcontents);
+      size_t descsz = elfcpp::Swap<32, big_endian>::readval(pcontents + 4);
+      unsigned int ntype = elfcpp::Swap<32, big_endian>::readval(pcontents + 8);
+      const unsigned char* pname = pcontents + 12;
+
+      if (namesz != 4 || strcmp(reinterpret_cast<const char*>(pname), "GNU") != 0)
+       {
+         gold_warning(_("%s: corrupt .note.gnu.property section "
+                        "(name is not 'GNU')"),
+                      this->name().c_str());
+         return;
+       }
+
+      if (ntype != elfcpp::NT_GNU_PROPERTY_TYPE_0)
+       {
+         gold_warning(_("%s: unsupported note type %d "
+                        "in .note.gnu.property section"),
+                      this->name().c_str(), ntype);
+         return;
+       }
+
+      size_t aligned_namesz = align_address(namesz, 4);
+      const unsigned char* pdesc = pname + aligned_namesz;
+
+      if (pdesc + descsz > pcontents + contents_len)
+       {
+         gold_warning(_("%s: corrupt .note.gnu.property section"),
+                      this->name().c_str());
+         return;
+       }
+
+      const unsigned char* pprop = pdesc;
+
+      // Loop over the program properties in this note.
+      while (pprop < pdesc + descsz)
+       {
+         if (pprop + 8 > pdesc + descsz)
+           {
+             gold_warning(_("%s: corrupt .note.gnu.property section"),
+                          this->name().c_str());
+             return;
+           }
+         unsigned int pr_type = elfcpp::Swap<32, big_endian>::readval(pprop);
+         size_t pr_datasz = elfcpp::Swap<32, big_endian>::readval(pprop + 4);
+         pprop += 8;
+         if (pprop + pr_datasz > pdesc + descsz)
+           {
+             gold_warning(_("%s: corrupt .note.gnu.property section"),
+                          this->name().c_str());
+             return;
+           }
+         layout->layout_gnu_property(ntype, pr_type, pr_datasz, pprop, this);
+         pprop += align_address(pr_datasz, size / 8);
+       }
+
+      pcontents = pdesc + align_address(descsz, size / 8);
+    }
+}
+
+// This a copy of lto_section defined in GCC (lto-streamer.h)
+
+struct lto_section
+{
+  int16_t major_version;
+  int16_t minor_version;
+  unsigned char slim_object;
+
+  /* Flags is a private field that is not defined publicly.  */
+  uint16_t flags;
+};
+
 // 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.  
-// 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.
+// and an offset.
+// This function is called twice sometimes, two passes, when mapping
+// of input sections to output sections must be delayed.
+// This is true for the following :
+// * Garbage collection (--gc-sections): Some input sections will be
+// discarded and hence the assignment must wait until the second pass.
+// In the first pass,  it is for setting up some sections as roots to
+// a work-list for --gc-sections and to do comdat processing.
+// * Identical Code Folding (--icf=<safe,all>): Some input sections
+// will be folded and hence the assignment must wait.
+// * Using plugins to map some sections to unique segments: Mapping
+// some sections to unique segments requires mapping them to unique
+// output sections too.  This can be done via plugins now and this
+// information is not available in the first pass.
 
 template<int size, bool big_endian>
 void
@@ -1060,54 +1416,68 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
                                               Layout* layout,
                                               Read_symbols_data* sd)
 {
+  const unsigned int unwind_section_type =
+      parameters->target().unwind_section_type();
   const unsigned int 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));
 
+  /* Should this function be called twice?  */
+  bool is_two_pass = (parameters->options().gc_sections()
+                     || parameters->options().icf_enabled()
+                     || layout->is_unique_segment_for_sections_specified());
+
+  /* Only one of is_pass_one and is_pass_two is true.  Both are false when
+     a two-pass approach is not needed.  */
+  bool is_pass_one = false;
+  bool is_pass_two = false;
+
+  Symbols_data* gc_sd = NULL;
+
+  /* Check if do_layout needs to be two-pass.  If so, find out which pass
+     should happen.  In the first pass, the data in sd is saved to be used
+     later in the second pass.  */
+  if (is_two_pass)
+    {
+      gc_sd = this->get_symbols_data();
+      if (gc_sd == NULL)
+       {
+         gold_assert(sd != NULL);
+         is_pass_one = true;
+       }
+      else
+       {
+         if (parameters->options().gc_sections())
+           gold_assert(symtab->gc()->is_worklist_ready());
+         if (parameters->options().icf_enabled())
+           gold_assert(symtab->icf()->is_icf_ready()); 
+         is_pass_two = true;
+       }
+    }
+    
   if (shnum == 0)
     return;
-  Symbols_data* gc_sd = NULL;
-  if (is_gc_pass_one)
+
+  if (is_pass_one)
     {
-      // During garbage collection save the symbols data to use it when 
-      // re-entering this function.   
+      // 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 * 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)
+
+  if (is_two_pass)
     {
       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;
     }
@@ -1116,11 +1486,10 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
       section_headers_data = sd->section_headers->data();
       section_names_size = sd->section_names_size;
       if (sd->symbols != NULL)
-        symbols_data = sd->symbols->data();
+       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_data = sd->symbol_names->data();
       symbol_names_size = sd->symbol_names_size;
     }
 
@@ -1129,9 +1498,9 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
   const unsigned char* pshdrs;
 
   // Get the section names.
-  const unsigned char* pnamesu = (is_gc_or_icf) 
-                                 ? gc_sd->section_names_data
-                                 : sd->section_names->data();
+  const unsigned char* pnamesu = (is_two_pass
+                                 ? gc_sd->section_names_data
+                                 : sd->section_names->data());
 
   const char* pnames = reinterpret_cast<const char*>(pnamesu);
 
@@ -1155,7 +1524,7 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
 
       // 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;
+       ++num_sections_to_defer;
 
       unsigned int sh_type = shdr.get_sh_type();
       if (sh_type == elfcpp::SHT_REL || sh_type == elfcpp::SHT_RELA)
@@ -1181,7 +1550,7 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
   Output_sections& out_sections(this->output_sections());
   std::vector<Address>& out_section_offsets(this->section_offsets());
 
-  if (!is_gc_pass_two)
+  if (!is_pass_two)
     {
       out_sections.resize(shnum);
       out_section_offsets.resize(shnum);
@@ -1191,13 +1560,13 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
   // do here.
   if (this->input_file()->just_symbols())
     {
-      if (!is_gc_pass_two)
-        {
-          delete sd->section_headers;
-          sd->section_headers = NULL;
-          delete sd->section_names;
-          sd->section_names = NULL;
-        }
+      if (!is_pass_two)
+       {
+         delete sd->section_headers;
+         sd->section_headers = NULL;
+         delete sd->section_names;
+         sd->section_names = NULL;
+       }
       return;
     }
 
@@ -1205,6 +1574,7 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
     {
       parameters->options().plugins()->add_deferred_layout_object(this);
       this->deferred_layout_.reserve(num_sections_to_defer);
+      this->is_deferred_layout_ = true;
     }
 
   // Whether we've seen a .note.GNU-stack section.
@@ -1224,46 +1594,51 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
   // Keep track of .eh_frame sections.
   std::vector<unsigned int> eh_frame_sections;
 
+  // Keep track of .debug_info and .debug_types sections.
+  std::vector<unsigned int> debug_info_sections;
+  std::vector<unsigned int> debug_types_sections;
+
   // Skip the first, dummy, section.
   pshdrs = shdrs + This::shdr_size;
   for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
     {
       typename This::Shdr shdr(pshdrs);
+      const unsigned int sh_name = shdr.get_sh_name();
+      unsigned int sh_type = shdr.get_sh_type();
 
-      if (shdr.get_sh_name() >= section_names_size)
+      if (sh_name >= section_names_size)
        {
          this->error(_("bad section name offset for section %u: %lu"),
-                     i, static_cast<unsigned long>(shdr.get_sh_name()));
+                     i, static_cast<unsigned long>(sh_name));
          return;
        }
 
-      const char* name = pnames + shdr.get_sh_name();
+      const char* name = pnames + sh_name;
 
-      if (!is_gc_pass_two)
-        { 
-          if (this->handle_gnu_warning_section(name, i, symtab))
-            { 
-             if (!relocatable)
-               omit[i] = true;
+      if (!is_pass_two)
+       {
+         if (this->handle_gnu_warning_section(name, i, symtab))
+           {
+             if (!relocatable && !parameters->options().shared())
+               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)
-            {
+         // 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-split-stack section is also special.  It
          // indicates that the object was compiled with
          // -fsplit-stack.
          if (this->handle_split_stack_section(name))
            {
-             if (!parameters->options().relocatable()
-                 && !parameters->options().shared())
+             if (!relocatable && !parameters->options().shared())
                omit[i] = true;
            }
 
@@ -1273,61 +1648,73 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
              omit[i] = true;
            }
 
-          bool discard = omit[i];
-          if (!discard)
-            {
-             if (shdr.get_sh_type() == elfcpp::SHT_GROUP)
-               {
-                 if (!this->include_section_group(symtab, layout, i, name, 
-                                                   shdrs, pnames, 
-                                                   section_names_size,
-                                                  &omit))
+         // Handle .note.gnu.property sections.
+         if (sh_type == elfcpp::SHT_NOTE
+             && strcmp(name, ".note.gnu.property") == 0)
+           {
+             this->layout_gnu_property_section(layout, i);
+             omit[i] = true;
+           }
+
+         bool discard = omit[i];
+         if (!discard)
+           {
+             if (sh_type == elfcpp::SHT_GROUP)
+               {
+                 if (!this->include_section_group(symtab, layout, i, name,
+                                                  shdrs, pnames,
+                                                  section_names_size,
+                                                  &omit))
                    discard = true;
-               }
-              else if ((shdr.get_sh_flags() & elfcpp::SHF_GROUP) == 0
-                       && Layout::is_linkonce(name))
-               {
-                 if (!this->include_linkonce_section(layout, i, name, shdr))
-                   discard = true;
-               }
+               }
+             else if ((shdr.get_sh_flags() & elfcpp::SHF_GROUP) == 0
+                      && Layout::is_linkonce(name))
+               {
+                 if (!this->include_linkonce_section(layout, i, name, shdr))
+                   discard = true;
+               }
            }
 
          // Add the section to the incremental inputs layout.
          Incremental_inputs* incremental_inputs = layout->incremental_inputs();
          if (incremental_inputs != NULL
              && !discard
-             && (shdr.get_sh_type() == elfcpp::SHT_PROGBITS
-                 || shdr.get_sh_type() == elfcpp::SHT_NOBITS
-                 || shdr.get_sh_type() == elfcpp::SHT_NOTE))
-           incremental_inputs->report_input_section(this, i, name,
-                                                    shdr.get_sh_size());
-
-          if (discard)
-            {
+             && can_incremental_update(sh_type))
+           {
+             off_t sh_size = shdr.get_sh_size();
+             section_size_type uncompressed_size;
+             if (this->section_is_compressed(i, &uncompressed_size))
+               sh_size = uncompressed_size;
+             incremental_inputs->report_input_section(this, i, name, sh_size);
+           }
+
+         if (discard)
+           {
              // Do not include this section in the link.
              out_sections[i] = NULL;
-              out_section_offsets[i] = invalid_address;
+             out_section_offsets[i] = invalid_address;
              continue;
-            }
-        }
-      if (is_gc_pass_one && parameters->options().gc_sections())
-        {
-          if (this->is_section_name_included(name)
-              || shdr.get_sh_type() == elfcpp::SHT_INIT_ARRAY 
-              || shdr.get_sh_type() == elfcpp::SHT_FINI_ARRAY)
-            {
-              symtab->gc()->worklist().push(Section_id(this, i)); 
-            }
-          // If the section name XXX can be represented as a C identifier
-          // it cannot be discarded if there are references to
-          // __start_XXX and __stop_XXX symbols.  These need to be
-          // specially handled.
-          if (is_cident(name))
-            {
-              symtab->gc()->add_cident_section(name, Section_id(this, i));
-            }
-        }
+           }
+       }
+
+      if (is_pass_one && parameters->options().gc_sections())
+       {
+         if (this->is_section_name_included(name)
+             || layout->keep_input_section (this, name)
+             || sh_type == elfcpp::SHT_INIT_ARRAY
+             || sh_type == elfcpp::SHT_FINI_ARRAY)
+           {
+             symtab->gc()->worklist().push_back(Section_id(this, i));
+           }
+         // If the section name XXX can be represented as a C identifier
+         // it cannot be discarded if there are references to
+         // __start_XXX and __stop_XXX symbols.  These need to be
+         // specially handled.
+         if (is_cident(name))
+           {
+             symtab->gc()->add_cident_section(name, 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
@@ -1336,14 +1723,14 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
       // reloc sections and process them later. Garbage collection is
       // not triggered when relocatable code is desired.
       if (emit_relocs
-         && (shdr.get_sh_type() == elfcpp::SHT_REL
-             || shdr.get_sh_type() == elfcpp::SHT_RELA))
+         && (sh_type == elfcpp::SHT_REL
+             || sh_type == elfcpp::SHT_RELA))
        {
          reloc_sections.push_back(i);
          continue;
        }
 
-      if (relocatable && shdr.get_sh_type() == elfcpp::SHT_GROUP)
+      if (relocatable && sh_type == elfcpp::SHT_GROUP)
        continue;
 
       // The .eh_frame section is special.  It holds exception frame
@@ -1352,124 +1739,198 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
       // sections so that the exception frame reader can reliably
       // determine which sections are being discarded, and discard the
       // corresponding information.
-      if (!relocatable
-          && strcmp(name, ".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 (this->check_eh_frame_flags(&shdr)
+         && strcmp(name, ".eh_frame") == 0)
+       {
+         // If the target has a special unwind section type, let's
+         // canonicalize it here.
+         sh_type = unwind_section_type;
+         if (!relocatable)
+           {
+             if (is_pass_one)
+               {
+                 if (this->is_deferred_layout())
+                   out_sections[i] = reinterpret_cast<Output_section*>(2);
+                 else
+                   out_sections[i] = reinterpret_cast<Output_section*>(1);
+                 out_section_offsets[i] = invalid_address;
+               }
+             else if (this->is_deferred_layout())
+               {
+                 out_sections[i] = reinterpret_cast<Output_section*>(2);
+                 out_section_offsets[i] = invalid_address;
+                 this->deferred_layout_.push_back(
+                     Deferred_layout(i, name, sh_type, pshdrs,
+                                     reloc_shndx[i], reloc_type[i]));
+               }
+             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;
-              }
-        }
+      if (is_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;
+             }
+       }
 
-      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;
-              }
-        }
+      if (is_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;
+             }
+       }
 
       // 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, name, 
-                                                           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;
-        }
+      // is turned on this function is called twice; we only want to do this
+      // on the first pass.
+      if (!is_pass_two
+          && this->is_deferred_layout()
+          && (shdr.get_sh_flags() & elfcpp::SHF_ALLOC))
+       {
+         this->deferred_layout_.push_back(Deferred_layout(i, name, sh_type,
+                                                          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;
+       }
 
       // 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_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;
-        }
+      if (is_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(layout, i, name, shdr, reloc_shndx[i],
-                               reloc_type[i]);
-        }
+       {
+         // When garbage collection is switched on the actual layout
+         // only happens in the second call.
+         this->layout_section(layout, i, name, shdr, sh_type, reloc_shndx[i],
+                              reloc_type[i]);
+
+         // When generating a .gdb_index section, we do additional
+         // processing of .debug_info and .debug_types sections after all
+         // the other sections for the same reason as above.
+         if (!relocatable
+             && parameters->options().gdb_index()
+             && !(shdr.get_sh_flags() & elfcpp::SHF_ALLOC))
+           {
+             if (strcmp(name, ".debug_info") == 0
+                 || strcmp(name, ".zdebug_info") == 0)
+               debug_info_sections.push_back(i);
+             else if (strcmp(name, ".debug_types") == 0
+                      || strcmp(name, ".zdebug_types") == 0)
+               debug_types_sections.push_back(i);
+           }
+       }
+
+      /* GCC uses .gnu.lto_.lto.<some_hash> as a LTO bytecode information
+        section.  */
+      const char *lto_section_name = ".gnu.lto_.lto.";
+      if (strncmp (name, lto_section_name, strlen (lto_section_name)) == 0)
+       {
+         section_size_type contents_len;
+         const unsigned char* pcontents
+           = this->section_contents(i, &contents_len, false);
+         if (contents_len >= sizeof(lto_section))
+           {
+             const lto_section* lsection
+               = reinterpret_cast<const lto_section*>(pcontents);
+             if (lsection->slim_object)
+               layout->set_lto_slim_object();
+           }
+       }
     }
 
-  if (!is_gc_pass_two)
-    layout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags, this);
+  if (!is_pass_two)
+    {
+      layout->merge_gnu_properties(this);
+      layout->layout_gnu_stack(seen_gnu_stack, gnu_stack_flags, this);
+    }
+
+  // Handle the .eh_frame sections after the other sections.
+  gold_assert(!is_pass_one || eh_frame_sections.empty());
+  for (std::vector<unsigned int>::const_iterator p = eh_frame_sections.begin();
+       p != eh_frame_sections.end();
+       ++p)
+    {
+      unsigned int i = *p;
+      const unsigned char* pshdr;
+      pshdr = section_headers_data + i * This::shdr_size;
+      typename This::Shdr shdr(pshdr);
+
+      this->layout_eh_frame_section(layout,
+                                   symbols_data,
+                                   symbols_size,
+                                   symbol_names_data,
+                                   symbol_names_size,
+                                   i,
+                                   shdr,
+                                   reloc_shndx[i],
+                                   reloc_type[i]);
+    }
 
   // When doing a relocatable link handle the reloc sections at the
-  // end.  Garbage collection  and Identical Code Folding is not 
-  // turned on for relocatable code. 
+  // end.  Garbage collection  and Identical Code Folding is not
+  // turned on for relocatable code.
   if (emit_relocs)
     this->size_relocatable_relocs();
 
-  gold_assert(!(is_gc_or_icf) || reloc_sections.empty());
+  gold_assert(!is_two_pass || reloc_sections.empty());
 
   for (std::vector<unsigned int>::const_iterator p = reloc_sections.begin();
        p != reloc_sections.end();
@@ -1489,20 +1950,23 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
 
       Output_section* data_section = out_sections[data_shndx];
       if (data_section == reinterpret_cast<Output_section*>(2))
-        {
-          // The layout for the data section was deferred, so we need
-          // to defer the relocation section, too.
+       {
+         if (is_pass_two)
+           continue;
+         // The layout for the data section was deferred, so we need
+         // to defer the relocation section, too.
          const char* name = pnames + shdr.get_sh_name();
-          this->deferred_layout_relocs_.push_back(
-              Deferred_layout(i, name, pshdr, 0, elfcpp::SHT_NULL));
+         this->deferred_layout_relocs_.push_back(
+             Deferred_layout(i, name, shdr.get_sh_type(), pshdr, 0,
+                             elfcpp::SHT_NULL));
          out_sections[i] = reinterpret_cast<Output_section*>(2);
-          out_section_offsets[i] = invalid_address;
-          continue;
-        }
+         out_section_offsets[i] = invalid_address;
+         continue;
+       }
       if (data_section == NULL)
        {
          out_sections[i] = NULL;
-          out_section_offsets[i] = invalid_address;
+         out_section_offsets[i] = invalid_address;
          continue;
        }
 
@@ -1515,50 +1979,30 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
       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();
+  // When building a .gdb_index section, scan the .debug_info and
+  // .debug_types sections.
+  gold_assert(!is_pass_one
+             || (debug_info_sections.empty() && debug_types_sections.empty()));
+  for (std::vector<unsigned int>::const_iterator p
+          = debug_info_sections.begin();
+       p != debug_info_sections.end();
        ++p)
     {
-      gold_assert(this->has_eh_frame_);
-      gold_assert(external_symbols_offset != 0);
-
       unsigned int i = *p;
-      const unsigned char* pshdr;
-      pshdr = section_headers_data + i * This::shdr_size;
-      typename This::Shdr shdr(pshdr);
-
-      off_t offset;
-      Output_section* os = layout->layout_eh_frame(this,
-                                                  symbols_data,
-                                                  symbols_size,
-                                                  symbol_names_data,
-                                                  symbol_names_size,
-                                                  i, shdr,
-                                                  reloc_shndx[i],
-                                                  reloc_type[i],
-                                                  &offset);
-      out_sections[i] = os;
-      if (os == NULL || offset == -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>(offset);
-
-      // 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 (os != NULL && offset == -1 && reloc_shndx[i] != 0)
-       this->set_relocs_must_follow_section_writes();
+      layout->add_to_gdb_index(false, this, symbols_data, symbols_size,
+                              i, reloc_shndx[i], reloc_type[i]);
+    }
+  for (std::vector<unsigned int>::const_iterator p
+          = debug_types_sections.begin();
+       p != debug_types_sections.end();
+       ++p)
+    {
+      unsigned int i = *p;
+      layout->add_to_gdb_index(true, this, symbols_data, symbols_size,
+                              i, reloc_shndx[i], reloc_type[i]);
     }
 
-  if (is_gc_pass_two)
+  if (is_pass_two)
     {
       delete[] gc_sd->section_headers_data;
       delete[] gc_sd->section_names_data;
@@ -1589,13 +2033,44 @@ Sized_relobj_file<size, big_endian>::do_layout_deferred_sections(Layout* layout)
        ++deferred)
     {
       typename This::Shdr shdr(deferred->shdr_data_);
+
+      if (!parameters->options().relocatable()
+         && deferred->name_ == ".eh_frame"
+         && this->check_eh_frame_flags(&shdr))
+       {
+         // Checking is_section_included is not reliable for
+         // .eh_frame sections, because they do not have an output
+         // section.  This is not a problem normally because we call
+         // layout_eh_frame_section unconditionally, but when
+         // deferring sections that is not true.  We don't want to
+         // keep all .eh_frame sections because that will cause us to
+         // keep all sections that they refer to, which is the wrong
+         // way around.  Instead, the eh_frame code will discard
+         // .eh_frame sections that refer to discarded sections.
+
+         // Reading the symbols again here may be slow.
+         Read_symbols_data sd;
+         this->base_read_symbols(&sd);
+         this->layout_eh_frame_section(layout,
+                                       sd.symbols->data(),
+                                       sd.symbols_size,
+                                       sd.symbol_names->data(),
+                                       sd.symbol_names_size,
+                                       deferred->shndx_,
+                                       shdr,
+                                       deferred->reloc_shndx_,
+                                       deferred->reloc_type_);
+         continue;
+       }
+
       // If the section is not included, it is because the garbage collector
       // decided it is not needed.  Avoid reverting that decision.
       if (!this->is_section_included(deferred->shndx_))
-        continue;
+       continue;
 
       this->layout_section(layout, deferred->shndx_, deferred->name_.c_str(),
-                           shdr, deferred->reloc_shndx_, deferred->reloc_type_);
+                          shdr, shdr.get_sh_type(), deferred->reloc_shndx_,
+                          deferred->reloc_type_);
     }
 
   this->deferred_layout_.clear();
@@ -1617,7 +2092,7 @@ Sized_relobj_file<size, big_endian>::do_layout_deferred_sections(Layout* layout)
       if (data_section == NULL)
        {
          out_sections[shndx] = NULL;
-          out_section_offsets[shndx] = invalid_address;
+         out_section_offsets[shndx] = invalid_address;
          continue;
        }
 
@@ -1637,7 +2112,7 @@ template<int size, bool big_endian>
 void
 Sized_relobj_file<size, big_endian>::do_add_symbols(Symbol_table* symtab,
                                                    Read_symbols_data* sd,
-                                                   Layout*)
+                                                   Layout* layout)
 {
   if (sd->symbols == NULL)
     {
@@ -1656,6 +2131,11 @@ Sized_relobj_file<size, big_endian>::do_add_symbols(Symbol_table* symtab,
 
   this->symbols_.resize(symcount);
 
+  if (!parameters->options().relocatable()
+      && layout->is_lto_slim_object ())
+    gold_info(_("%s: plugin needed to handle lto object"),
+             this->name().c_str());
+
   const char* sym_names =
     reinterpret_cast<const char*>(sd->symbol_names->data());
   symtab->add_from_relobj(this,
@@ -1692,7 +2172,7 @@ Sized_relobj_file<size, big_endian>::do_should_include_member(
       sd->symbols->data() + sd->external_symbols_offset;
   const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
   size_t symcount = ((sd->symbols_size - sd->external_symbols_offset)
-                         / sym_size);
+                        / sym_size);
 
   const unsigned char* p = syms;
 
@@ -1738,7 +2218,7 @@ Sized_relobj_file<size, big_endian>::do_for_all_global_symbols(
       sd->symbols->data() + sd->external_symbols_offset;
   const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
   size_t symcount = ((sd->symbols_size - sd->external_symbols_offset)
-                     / sym_size);
+                    / sym_size);
   const unsigned char* p = syms;
 
   for (size_t i = 0; i < symcount; ++i, p += sym_size)
@@ -1765,7 +2245,8 @@ Sized_relobj_file<size, big_endian>::local_has_plt_offset(
 
 template<int size, bool big_endian>
 unsigned int
-Sized_relobj_file<size, big_endian>::local_plt_offset(unsigned int symndx) const
+Sized_relobj_file<size, big_endian>::do_local_plt_offset(
+    unsigned int symndx) const
 {
   typename Local_plt_offsets::const_iterator p =
     this->local_plt_offsets_.find(symndx);
@@ -1829,6 +2310,7 @@ Sized_relobj_file<size, big_endian>::do_count_local_symbols(Stringpool* pool,
   // Loop over the local symbols.
 
   const Output_sections& out_sections(this->output_sections());
+  std::vector<Address>& out_section_offsets(this->section_offsets());
   unsigned int shnum = this->shnum();
   unsigned int count = 0;
   unsigned int dyncount = 0;
@@ -1837,6 +2319,7 @@ Sized_relobj_file<size, big_endian>::do_count_local_symbols(Stringpool* pool,
   bool strip_all = parameters->options().strip_all();
   bool discard_all = parameters->options().discard_all();
   bool discard_locals = parameters->options().discard_locals();
+  bool discard_sec_merge = parameters->options().discard_sec_merge();
   for (unsigned int i = 1; i < loccount; ++i, psyms += sym_size)
     {
       elfcpp::Sym<size, big_endian> sym(psyms);
@@ -1860,18 +2343,24 @@ Sized_relobj_file<size, big_endian>::do_count_local_symbols(Stringpool* pool,
 
       // Decide whether this symbol should go into the output file.
 
-      if ((shndx < shnum && out_sections[shndx] == NULL)
-         || shndx == this->discarded_eh_frame_shndx_)
-        {
+      if (is_ordinary
+         && shndx < shnum
+         && (out_sections[shndx] == NULL
+             || (out_sections[shndx]->order() == ORDER_EHFRAME
+                 && out_section_offsets[shndx] == invalid_address)))
+       {
+         // This is either a discarded section or an optimized .eh_frame
+         // section.
          lv.set_no_output_symtab_entry();
-          gold_assert(!lv.needs_output_dynsym_entry());
-          continue;
-        }
+         gold_assert(!lv.needs_output_dynsym_entry());
+         continue;
+       }
 
-      if (sym.get_st_type() == elfcpp::STT_SECTION)
+      if (sym.get_st_type() == elfcpp::STT_SECTION
+         || !this->adjust_local_symbol(&lv))
        {
          lv.set_no_output_symtab_entry();
-          gold_assert(!lv.needs_output_dynsym_entry());
+         gold_assert(!lv.needs_output_dynsym_entry());
          continue;
        }
 
@@ -1888,10 +2377,10 @@ Sized_relobj_file<size, big_endian>::do_count_local_symbols(Stringpool* pool,
 
       // If needed, add the symbol to the dynamic symbol table string pool.
       if (lv.needs_output_dynsym_entry())
-        {
-          dynpool->add(name, true, NULL);
-          ++dyncount;
-        }
+       {
+         dynpool->add(name, true, NULL);
+         ++dyncount;
+       }
 
       if (strip_all
          || (discard_all && lv.may_be_discarded_from_output_symtab()))
@@ -1900,6 +2389,7 @@ Sized_relobj_file<size, big_endian>::do_count_local_symbols(Stringpool* pool,
          continue;
        }
 
+      // By default, discard temporary local symbols in merge sections.
       // 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
@@ -1912,7 +2402,10 @@ Sized_relobj_file<size, big_endian>::do_count_local_symbols(Stringpool* pool,
       //   - the symbol has a name.
       //
       // We do not discard a symbol if it needs a dynamic symbol entry.
-      if (discard_locals
+      if ((discard_locals
+          || (discard_sec_merge
+              && is_ordinary
+              && out_section_offsets[shndx] == invalid_address))
          && sym.get_st_type() != elfcpp::STT_FILE
          && !lv.needs_output_dynsym_entry()
          && lv.may_be_discarded_from_output_symtab()
@@ -1925,10 +2418,10 @@ Sized_relobj_file<size, big_endian>::do_count_local_symbols(Stringpool* pool,
       // 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(name))
-        {
-          lv.set_no_output_symtab_entry();
-          continue;
-        }
+       {
+         lv.set_no_output_symtab_entry();
+         continue;
+       }
 
       // Add the symbol to the symbol table string pool.
       pool->add(name, true, NULL);
@@ -1958,9 +2451,9 @@ Sized_relobj_file<size, big_endian>::compute_final_local_value_internal(
 
   bool is_ordinary;
   unsigned int shndx = lv_in->input_shndx(&is_ordinary);
-  
+
   // Set the output symbol value.
-  
+
   if (!is_ordinary)
     {
       if (shndx == elfcpp::SHN_ABS || Symbol::is_common_shndx(shndx))
@@ -1982,7 +2475,7 @@ Sized_relobj_file<size, big_endian>::compute_final_local_value_internal(
          lv_out->set_output_value(0);
          return This::CFLV_ERROR;
        }
-      
+
       Output_section* os = out_sections[shndx];
       Address secoffset = out_offsets[shndx];
       if (symtab->is_section_folded(this, shndx))
@@ -1997,7 +2490,7 @@ Sized_relobj_file<size, big_endian>::compute_final_local_value_internal(
          os = folded_obj->output_section(folded.second);
          gold_assert(os != NULL);
          secoffset = folded_obj->get_output_section_offset(folded.second);
-         
+
          // This could be a relaxed input section.
          if (secoffset == invalid_address)
            {
@@ -2007,7 +2500,7 @@ Sized_relobj_file<size, big_endian>::compute_final_local_value_internal(
              secoffset = relaxed_section->address() - os->address();
            }
        }
-      
+
       if (os == NULL)
        {
          // This local symbol belongs to a section we are discarding.
@@ -2019,13 +2512,13 @@ Sized_relobj_file<size, big_endian>::compute_final_local_value_internal(
       else if (secoffset == invalid_address)
        {
          uint64_t start;
-         
+
          // This is a SHF_MERGE section or one which otherwise
          // requires special handling.
-         if (shndx == this->discarded_eh_frame_shndx_)
+         if (os->order() == ORDER_EHFRAME)
            {
-             // This local symbol belongs to a discarded .eh_frame
-             // section.  Just treat it like the case in which
+             // This local symbol belongs to a discarded or optimized
+             // .eh_frame section.  Just treat it like the case in which
              // os == NULL above.
              gold_assert(this->has_eh_frame_);
              return This::CFLV_DISCARDED;
@@ -2034,8 +2527,11 @@ Sized_relobj_file<size, big_endian>::compute_final_local_value_internal(
            {
              // This is not a section symbol.  We can determine
              // the final value now.
-             lv_out->set_output_value(
-                 os->output_address(this, shndx, lv_in->input_value()));
+             uint64_t value =
+               os->output_address(this, shndx, lv_in->input_value());
+             if (relocatable)
+               value -= os->address();
+             lv_out->set_output_value(value);
            }
          else if (!os->find_starting_output_address(this, shndx, &start))
            {
@@ -2049,10 +2545,10 @@ Sized_relobj_file<size, big_endian>::compute_final_local_value_internal(
                os->find_relaxed_input_section(this, shndx);
              if (posd != NULL)
                {
-                 Address relocatable_link_adjustment =
-                   relocatable ? os->address() : 0;
-                 lv_out->set_output_value(posd->address()
-                                          - relocatable_link_adjustment);
+                 uint64_t value = posd->address();
+                 if (relocatable)
+                   value -= os->address();
+                 lv_out->set_output_value(value);
                }
              else
                lv_out->set_output_value(os->address());
@@ -2072,7 +2568,9 @@ Sized_relobj_file<size, big_endian>::compute_final_local_value_internal(
              lv_out->set_merged_symbol_value(msv);
            }
        }
-      else if (lv_in->is_tls_symbol())
+      else if (lv_in->is_tls_symbol()
+               || (lv_in->is_section_symbol()
+                   && (os->flags() & elfcpp::SHF_TLS)))
        lv_out->set_output_value(os->tls_offset()
                                 + secoffset
                                 + lv_in->input_value());
@@ -2148,6 +2646,10 @@ Sized_relobj_file<size, big_endian>::do_finalize_local_symbols(
              lv->set_output_symtab_index(index);
              ++index;
            }
+         if (lv->is_ifunc_symbol()
+             && (lv->has_output_symtab_entry()
+                 || lv->needs_output_dynsym_entry()))
+           symtab->set_has_gnu_output();
          break;
        case CFLV_DISCARDED:
        case CFLV_ERROR:
@@ -2172,10 +2674,10 @@ Sized_relobj_file<size, big_endian>::do_set_local_dynsym_indexes(
     {
       Symbol_value<size>& lv(this->local_values_[i]);
       if (lv.needs_output_dynsym_entry())
-        {
-          lv.set_output_dynsym_index(index);
-          ++index;
-        }
+       {
+         lv.set_output_dynsym_index(index);
+         ++index;
+       }
     }
   return index;
 }
@@ -2204,12 +2706,12 @@ Sized_relobj_file<size, big_endian>::do_section_flags(unsigned int shndx)
   if (sd != NULL)
     {
       const unsigned char* pshdrs = sd->section_headers_data
-                                    + This::shdr_size * shndx;
+                                   + This::shdr_size * shndx;
       typename This::Shdr shdr(pshdrs);
-      return shdr.get_sh_flags(); 
+      return shdr.get_sh_flags();
     }
   // If sd is NULL, read the section header from the file.
-  return this->elf_file_.section_flags(shndx); 
+  return this->elf_file_.section_flags(shndx);
 }
 
 // Get the section's ent size from Symbols_data.  Called by get_section_contents
@@ -2223,9 +2725,9 @@ Sized_relobj_file<size, big_endian>::do_section_entsize(unsigned int shndx)
   gold_assert(sd != NULL);
 
   const unsigned char* pshdrs = sd->section_headers_data
-                                + This::shdr_size * shndx;
+                               + This::shdr_size * shndx;
   typename This::Shdr shdr(pshdrs);
-  return shdr.get_sh_entsize(); 
+  return shdr.get_sh_entsize();
 }
 
 // Write out the local symbols.
@@ -2290,9 +2792,9 @@ Sized_relobj_file<size, big_endian>::write_local_symbols(
   unsigned char* dyn_oview = NULL;
   if (dyn_output_size > 0)
     dyn_oview = of->get_output_view(this->local_dynsym_offset_,
-                                    dyn_output_size);
+                                   dyn_output_size);
 
-  const Output_sections out_sections(this->output_sections());
+  const Output_sections& out_sections(this->output_sections());
 
   gold_assert(this->local_values_.size() == loccount);
 
@@ -2326,38 +2828,38 @@ Sized_relobj_file<size, big_endian>::write_local_symbols(
 
       // Write the symbol to the output symbol table.
       if (lv.has_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));
-          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;
-        }
+       {
+         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));
+         osym.put_st_value(lv.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;
+       }
 
       // Write the symbol to the output dynamic symbol table.
       if (lv.has_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));
-          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;
-        }
+       {
+         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));
+         osym.put_st_value(lv.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;
+       }
     }
 
 
@@ -2372,7 +2874,7 @@ Sized_relobj_file<size, big_endian>::write_local_symbols(
     {
       gold_assert(dyn_ov - dyn_oview == dyn_output_size);
       of->write_output_view(this->local_dynsym_offset_, dyn_output_size,
-                            dyn_oview);
+                           dyn_oview);
     }
 }
 
@@ -2427,26 +2929,27 @@ Sized_relobj_file<size, big_endian>::get_symbol_location_info(
          && static_cast<off_t>(sym.get_st_value()) <= offset
          && (static_cast<off_t>(sym.get_st_value() + sym.get_st_size())
              > offset))
-        {
-          if (sym.get_st_name() > names_size)
+       {
+         info->enclosing_symbol_type = sym.get_st_type();
+         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().do_demangle())
-                {
-                  char* demangled_name = cplus_demangle(
-                      info->enclosing_symbol_name.c_str(),
-                      DMGL_ANSI | DMGL_PARAMS);
-                  if (demangled_name != NULL)
-                    {
-                      info->enclosing_symbol_name.assign(demangled_name);
-                      free(demangled_name);
-                    }
-                }
-            }
+           {
+             info->enclosing_symbol_name = symbol_names + sym.get_st_name();
+             if (parameters->options().do_demangle())
+               {
+                 char* demangled_name = cplus_demangle(
+                     info->enclosing_symbol_name.c_str(),
+                     DMGL_ANSI | DMGL_PARAMS);
+                 if (demangled_name != NULL)
+                   {
+                     info->enclosing_symbol_name.assign(demangled_name);
+                     free(demangled_name);
+                   }
+               }
+           }
          return true;
-        }
+       }
     }
 
   return false;
@@ -2460,26 +2963,117 @@ template<int size, bool big_endian>
 typename Sized_relobj_file<size, big_endian>::Address
 Sized_relobj_file<size, big_endian>::map_to_kept_section(
     unsigned int shndx,
-    bool* found) const
+    std::string& section_name,
+    bool* pfound) const
 {
-  Relobj* kept_object;
-  unsigned int kept_shndx;
-  if (this->get_kept_comdat_section(shndx, &kept_object, &kept_shndx))
+  Kept_section* kept_section;
+  bool is_comdat;
+  uint64_t sh_size;
+  unsigned int symndx;
+  bool found = false;
+
+  if (this->get_kept_comdat_section(shndx, &is_comdat, &symndx, &sh_size,
+                                   &kept_section))
     {
-      Sized_relobj_file<size, big_endian>* kept_relobj =
-       static_cast<Sized_relobj_file<size, big_endian>*>(kept_object);
-      Output_section* os = kept_relobj->output_section(kept_shndx);
-      Address offset = kept_relobj->get_output_section_offset(kept_shndx);
-      if (os != NULL && offset != invalid_address)
+      Relobj* kept_object = kept_section->object();
+      unsigned int kept_shndx = 0;
+      if (!kept_section->is_comdat())
+        {
+         // The kept section is a linkonce section.
+         if (sh_size == kept_section->linkonce_size())
+           found = true;
+        }
+      else
        {
-         *found = true;
-         return os->address() + offset;
+         if (is_comdat)
+           {
+             // Find the corresponding kept section.
+             // Since we're using this mapping for relocation processing,
+             // we don't want to match sections unless they have the same
+             // size.
+             uint64_t kept_size = 0;
+             if (kept_section->find_comdat_section(section_name, &kept_shndx,
+                                                   &kept_size))
+               {
+                 if (sh_size == kept_size)
+                   found = true;
+               }
+           }
+         else
+           {
+             uint64_t kept_size = 0;
+             if (kept_section->find_single_comdat_section(&kept_shndx,
+                                                          &kept_size)
+                 && sh_size == kept_size)
+               found = true;
+           }
+       }
+
+      if (found)
+       {
+         Sized_relobj_file<size, big_endian>* kept_relobj =
+           static_cast<Sized_relobj_file<size, big_endian>*>(kept_object);
+         Output_section* os = kept_relobj->output_section(kept_shndx);
+         Address offset = kept_relobj->get_output_section_offset(kept_shndx);
+         if (os != NULL && offset != invalid_address)
+           {
+             *pfound = true;
+             return os->address() + offset;
+           }
        }
     }
-  *found = false;
+  *pfound = false;
   return 0;
 }
 
+// Look for a kept section corresponding to the given discarded section,
+// and return its object file.
+
+template<int size, bool big_endian>
+Relobj*
+Sized_relobj_file<size, big_endian>::find_kept_section_object(
+    unsigned int shndx, unsigned int *symndx_p) const
+{
+  Kept_section* kept_section;
+  bool is_comdat;
+  uint64_t sh_size;
+  if (this->get_kept_comdat_section(shndx, &is_comdat, symndx_p, &sh_size,
+                                   &kept_section))
+    return kept_section->object();
+  return NULL;
+}
+
+// Return the name of symbol SYMNDX.
+
+template<int size, bool big_endian>
+const char*
+Sized_relobj_file<size, big_endian>::get_symbol_name(unsigned int symndx)
+{
+  if (this->symtab_shndx_ == 0)
+    return NULL;
+
+  section_size_type symbols_size;
+  const unsigned char* symbols = this->section_contents(this->symtab_shndx_,
+                                                       &symbols_size,
+                                                       false);
+
+  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 unsigned char* p = symbols + symndx * This::sym_size;
+
+  if (p >= symbols + symbols_size)
+    return NULL;
+
+  elfcpp::Sym<size, big_endian> sym(p);
+
+  return symbol_names + sym.get_st_name();
+}
+
 // Get symbol counts.
 
 template<int size, bool big_endian>
@@ -2502,6 +3096,91 @@ Sized_relobj_file<size, big_endian>::do_get_global_symbol_counts(
   *used = count;
 }
 
+// Return a view of the decompressed contents of a section.  Set *PLEN
+// to the size.  Set *IS_NEW to true if the contents need to be freed
+// by the caller.
+
+const unsigned char*
+Object::decompressed_section_contents(
+    unsigned int shndx,
+    section_size_type* plen,
+    bool* is_new,
+    uint64_t* palign)
+{
+  section_size_type buffer_size;
+  const unsigned char* buffer = this->do_section_contents(shndx, &buffer_size,
+                                                         false);
+
+  if (this->compressed_sections_ == NULL)
+    {
+      *plen = buffer_size;
+      *is_new = false;
+      return buffer;
+    }
+
+  Compressed_section_map::const_iterator p =
+      this->compressed_sections_->find(shndx);
+  if (p == this->compressed_sections_->end())
+    {
+      *plen = buffer_size;
+      *is_new = false;
+      return buffer;
+    }
+
+  section_size_type uncompressed_size = p->second.size;
+  if (p->second.contents != NULL)
+    {
+      *plen = uncompressed_size;
+      *is_new = false;
+      if (palign != NULL)
+       *palign = p->second.addralign;
+      return p->second.contents;
+    }
+
+  unsigned char* uncompressed_data = new unsigned char[uncompressed_size];
+  if (!decompress_input_section(buffer,
+                               buffer_size,
+                               uncompressed_data,
+                               uncompressed_size,
+                               elfsize(),
+                               is_big_endian(),
+                               p->second.flag))
+    this->error(_("could not decompress section %s"),
+               this->do_section_name(shndx).c_str());
+
+  // We could cache the results in p->second.contents and store
+  // false in *IS_NEW, but build_compressed_section_map() would
+  // have done so if it had expected it to be profitable.  If
+  // we reach this point, we expect to need the contents only
+  // once in this pass.
+  *plen = uncompressed_size;
+  *is_new = true;
+  if (palign != NULL)
+    *palign = p->second.addralign;
+  return uncompressed_data;
+}
+
+// Discard any buffers of uncompressed sections.  This is done
+// at the end of the Add_symbols task.
+
+void
+Object::discard_decompressed_sections()
+{
+  if (this->compressed_sections_ == NULL)
+    return;
+
+  for (Compressed_section_map::iterator p = this->compressed_sections_->begin();
+       p != this->compressed_sections_->end();
+       ++p)
+    {
+      if (p->second.contents != NULL)
+       {
+         delete[] p->second.contents;
+         p->second.contents = NULL;
+       }
+    }
+}
+
 // Input_objects methods.
 
 // Add a regular relocatable object to the list.  Return false if this
@@ -2522,11 +3201,20 @@ Input_objects::add_object(Object* obj)
       Dynobj* dynobj = static_cast<Dynobj*>(obj);
       const char* soname = dynobj->soname();
 
-      std::pair<Unordered_set<std::string>::iterator, bool> ins =
-       this->sonames_.insert(soname);
+      Unordered_map<std::string, Object*>::value_type val(soname, obj);
+      std::pair<Unordered_map<std::string, Object*>::iterator, bool> ins =
+       this->sonames_.insert(val);
       if (!ins.second)
        {
          // We have already seen a dynamic object with this soname.
+         // If any instances of this object on the command line have
+         // the --no-as-needed flag, make sure the one we keep is
+         // marked so.
+         if (!obj->as_needed())
+           {
+             gold_assert(ins.first->second != NULL);
+             ins.first->second->clear_as_needed();
+           }
          return false;
        }
 
@@ -2658,12 +3346,10 @@ Relocate_info<size, big_endian>::location(size_t, off_t offset) const
          ret += ":";
          ret += info.source_file;
        }
-      size_t len = info.enclosing_symbol_name.length() + 100;
-      char* buf = new char[len];
-      snprintf(buf, len, _(":function %s"),
-              info.enclosing_symbol_name.c_str());
-      ret += buf;
-      delete[] buf;
+      ret += ":";
+      if (info.enclosing_symbol_type == elfcpp::STT_FUNC)
+       ret += _("function ");
+      ret += info.enclosing_symbol_name;
       return ret;
     }
 
@@ -2691,7 +3377,8 @@ make_elf_sized_object(const std::string& name, Input_file* input_file,
                      off_t offset, const elfcpp::Ehdr<size, big_endian>& ehdr,
                      bool* punconfigured)
 {
-  Target* target = select_target(ehdr.get_e_machine(), size, big_endian,
+  Target* target = select_target(input_file, offset,
+                                ehdr.get_e_machine(), size, big_endian,
                                 ehdr.get_e_ident()[elfcpp::EI_OSABI],
                                 ehdr.get_e_ident()[elfcpp::EI_ABIVERSION]);
   if (target == NULL)
@@ -2751,7 +3438,7 @@ make_elf_object(const std::string& name, Input_file* input_file, off_t offset,
   bool big_endian = false;
   int size = 0;
   if (!elfcpp::Elf_recognizer::is_valid_header(p, bytes, &size,
-                                               &big_endian, &error))
+                                              &big_endian, &error))
     {
       gold_error(_("%s: %s"), name.c_str(), error.c_str());
       return NULL;
@@ -2833,11 +3520,33 @@ make_elf_object(const std::string& name, Input_file* input_file, off_t offset,
 
 // Instantiate the templates we need.
 
+#if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
+template
+void
+Relobj::initialize_input_to_output_map<64>(unsigned int shndx,
+      elfcpp::Elf_types<64>::Elf_Addr starting_address,
+      Unordered_map<section_offset_type,
+      elfcpp::Elf_types<64>::Elf_Addr>* output_addresses) const;
+#endif
+
+#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
+template
+void
+Relobj::initialize_input_to_output_map<32>(unsigned int shndx,
+      elfcpp::Elf_types<32>::Elf_Addr starting_address,
+      Unordered_map<section_offset_type,
+      elfcpp::Elf_types<32>::Elf_Addr>* output_addresses) const;
+#endif
+
 #ifdef HAVE_TARGET_32_LITTLE
 template
 void
 Object::read_section_data<32, false>(elfcpp::Elf_file<32, false, Object>*,
                                     Read_symbols_data*);
+template
+const unsigned char*
+Object::find_shdr<32,false>(const unsigned char*, const char*, const char*,
+                           section_size_type, const unsigned char*) const;
 #endif
 
 #ifdef HAVE_TARGET_32_BIG
@@ -2845,6 +3554,10 @@ template
 void
 Object::read_section_data<32, true>(elfcpp::Elf_file<32, true, Object>*,
                                    Read_symbols_data*);
+template
+const unsigned char*
+Object::find_shdr<32,true>(const unsigned char*, const char*, const char*,
+                          section_size_type, const unsigned char*) const;
 #endif
 
 #ifdef HAVE_TARGET_64_LITTLE
@@ -2852,6 +3565,10 @@ template
 void
 Object::read_section_data<64, false>(elfcpp::Elf_file<64, false, Object>*,
                                     Read_symbols_data*);
+template
+const unsigned char*
+Object::find_shdr<64,false>(const unsigned char*, const char*, const char*,
+                           section_size_type, const unsigned char*) const;
 #endif
 
 #ifdef HAVE_TARGET_64_BIG
@@ -2859,24 +3576,40 @@ template
 void
 Object::read_section_data<64, true>(elfcpp::Elf_file<64, true, Object>*,
                                    Read_symbols_data*);
+template
+const unsigned char*
+Object::find_shdr<64,true>(const unsigned char*, const char*, const char*,
+                          section_size_type, const unsigned char*) const;
 #endif
 
 #ifdef HAVE_TARGET_32_LITTLE
+template
+class Sized_relobj<32, false>;
+
 template
 class Sized_relobj_file<32, false>;
 #endif
 
 #ifdef HAVE_TARGET_32_BIG
+template
+class Sized_relobj<32, true>;
+
 template
 class Sized_relobj_file<32, true>;
 #endif
 
 #ifdef HAVE_TARGET_64_LITTLE
+template
+class Sized_relobj<64, false>;
+
 template
 class Sized_relobj_file<64, false>;
 #endif
 
 #ifdef HAVE_TARGET_64_BIG
+template
+class Sized_relobj<64, true>;
+
 template
 class Sized_relobj_file<64, true>;
 #endif
@@ -2945,4 +3678,36 @@ Xindex::read_symtab_xindex<64, true>(Object*, unsigned int,
                                     const unsigned char*);
 #endif
 
+#ifdef HAVE_TARGET_32_LITTLE
+template
+Compressed_section_map*
+build_compressed_section_map<32, false>(const unsigned char*, unsigned int,
+                                       const char*, section_size_type, 
+                                       Object*, bool);
+#endif
+
+#ifdef HAVE_TARGET_32_BIG
+template
+Compressed_section_map*
+build_compressed_section_map<32, true>(const unsigned char*, unsigned int,
+                                       const char*, section_size_type, 
+                                       Object*, bool);
+#endif
+
+#ifdef HAVE_TARGET_64_LITTLE
+template
+Compressed_section_map*
+build_compressed_section_map<64, false>(const unsigned char*, unsigned int,
+                                       const char*, section_size_type, 
+                                       Object*, bool);
+#endif
+
+#ifdef HAVE_TARGET_64_BIG
+template
+Compressed_section_map*
+build_compressed_section_map<64, true>(const unsigned char*, unsigned int,
+                                       const char*, section_size_type, 
+                                       Object*, bool);
+#endif
+
 } // End namespace gold.
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