Add upstream binutils-2.25 snapshot 4/4 2014

For MIPS -mmsa support

Change-Id: I08c4f002fa7b33dec85ed75956e6ab551bb03c96

1 files changed, 888 insertions, 0 deletions

diff --git a/binutils-2.25/gold/gold.cc b/binutils-2.25/gold/gold.cc
new file mode 100644
index 00000000..4de9289b
--- /dev/null
+++ b/binutils-2.25/gold/gold.cc
@@ -0,0 +1,888 @@
+// gold.cc -- main linker functions
+
+// Copyright 2006, 2007, 2008, 2009, 2010, 2011, 2012
+// Free Software Foundation, Inc.
+// Written by Ian Lance Taylor <iant@google.com>.
+
+// This file is part of gold.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+// MA 02110-1301, USA.
+
+#include "gold.h"
+
+#include <cstdlib>
+#include <cstdio>
+#include <cstring>
+#include <unistd.h>
+#include <algorithm>
+#include "libiberty.h"
+
+#include "options.h"
+#include "target-select.h"
+#include "debug.h"
+#include "workqueue.h"
+#include "dirsearch.h"
+#include "readsyms.h"
+#include "symtab.h"
+#include "common.h"
+#include "object.h"
+#include "layout.h"
+#include "reloc.h"
+#include "defstd.h"
+#include "plugin.h"
+#include "gc.h"
+#include "icf.h"
+#include "incremental.h"
+#include "timer.h"
+
+namespace gold
+{
+
+class Object;
+
+const char* program_name;
+
+static Task*
+process_incremental_input(Incremental_binary*, unsigned int, Input_objects*,
+			  Symbol_table*, Layout*, Dirsearch*, Mapfile*,
+			  Task_token*, Task_token*);
+
+void
+gold_exit(Exit_status status)
+{
+  if (parameters != NULL
+      && parameters->options_valid()
+      && parameters->options().has_plugins())
+    parameters->options().plugins()->cleanup();
+  if (status != GOLD_OK && parameters != NULL && parameters->options_valid())
+    unlink_if_ordinary(parameters->options().output_file_name());
+  exit(status);
+}
+
+void
+gold_nomem()
+{
+  // We are out of memory, so try hard to print a reasonable message.
+  // Note that we don't try to translate this message, since the
+  // translation process itself will require memory.
+
+  // LEN only exists to avoid a pointless warning when write is
+  // declared with warn_use_result, as when compiling with
+  // -D_USE_FORTIFY on GNU/Linux.  Casting to void does not appear to
+  // work, at least not with gcc 4.3.0.
+
+  ssize_t len = write(2, program_name, strlen(program_name));
+  if (len >= 0)
+    {
+      const char* const s = ": out of memory\n";
+      len = write(2, s, strlen(s));
+    }
+  gold_exit(GOLD_ERR);
+}
+
+// Handle an unreachable case.
+
+void
+do_gold_unreachable(const char* filename, int lineno, const char* function)
+{
+  fprintf(stderr, _("%s: internal error in %s, at %s:%d\n"),
+	  program_name, function, filename, lineno);
+  gold_exit(GOLD_ERR);
+}
+
+// This class arranges to run the functions done in the middle of the
+// link.  It is just a closure.
+
+class Middle_runner : public Task_function_runner
+{
+ public:
+  Middle_runner(const General_options& options,
+		const Input_objects* input_objects,
+		Symbol_table* symtab,
+		Layout* layout, Mapfile* mapfile)
+    : options_(options), input_objects_(input_objects), symtab_(symtab),
+      layout_(layout), mapfile_(mapfile)
+  { }
+
+  void
+  run(Workqueue*, const Task*);
+
+ private:
+  const General_options& options_;
+  const Input_objects* input_objects_;
+  Symbol_table* symtab_;
+  Layout* layout_;
+  Mapfile* mapfile_;
+};
+
+void
+Middle_runner::run(Workqueue* workqueue, const Task* task)
+{
+  queue_middle_tasks(this->options_, task, this->input_objects_, this->symtab_,
+		     this->layout_, workqueue, this->mapfile_);
+}
+
+// This class arranges the tasks to process the relocs for garbage collection.
+
+class Gc_runner : public Task_function_runner
+{
+  public:
+   Gc_runner(const General_options& options,
+	     const Input_objects* input_objects,
+	     Symbol_table* symtab,
+	     Layout* layout, Mapfile* mapfile)
+    : options_(options), input_objects_(input_objects), symtab_(symtab),
+      layout_(layout), mapfile_(mapfile)
+   { }
+
+  void
+  run(Workqueue*, const Task*);
+
+ private:
+  const General_options& options_;
+  const Input_objects* input_objects_;
+  Symbol_table* symtab_;
+  Layout* layout_;
+  Mapfile* mapfile_;
+};
+
+void
+Gc_runner::run(Workqueue* workqueue, const Task* task)
+{
+  queue_middle_gc_tasks(this->options_, task, this->input_objects_,
+			this->symtab_, this->layout_, workqueue,
+			this->mapfile_);
+}
+
+// Queue up the initial set of tasks for this link job.
+
+void
+queue_initial_tasks(const General_options& options,
+		    Dirsearch& search_path,
+		    const Command_line& cmdline,
+		    Workqueue* workqueue, Input_objects* input_objects,
+		    Symbol_table* symtab, Layout* layout, Mapfile* mapfile)
+{
+  if (cmdline.begin() == cmdline.end())
+    {
+      bool is_ok = false;
+      if (options.printed_version())
+	is_ok = true;
+      if (options.print_output_format())
+	{
+	  print_output_format();
+	  is_ok = true;
+	}
+      if (is_ok)
+	gold_exit(GOLD_OK);
+      gold_fatal(_("no input files"));
+    }
+
+  int thread_count = options.thread_count_initial();
+  if (thread_count == 0)
+    thread_count = cmdline.number_of_input_files();
+  workqueue->set_thread_count(thread_count);
+
+  // For incremental links, the base output file.
+  Incremental_binary* ibase = NULL;
+
+  if (parameters->incremental_update())
+    {
+      Output_file* of = new Output_file(options.output_file_name());
+      if (of->open_base_file(options.incremental_base(), true))
+	{
+	  ibase = open_incremental_binary(of);
+	  if (ibase != NULL
+	      && ibase->check_inputs(cmdline, layout->incremental_inputs()))
+	    ibase->init_layout(layout);
+	  else
+	    {
+	      delete ibase;
+	      ibase = NULL;
+	      of->close();
+	    }
+	}
+      if (ibase == NULL)
+	{
+	  if (set_parameters_incremental_full())
+	    gold_info(_("linking with --incremental-full"));
+	  else
+	    gold_fallback(_("restart link with --incremental-full"));
+	}
+    }
+
+  // Read the input files.  We have to add the symbols to the symbol
+  // table in order.  We do this by creating a separate blocker for
+  // each input file.  We associate the blocker with the following
+  // input file, to give us a convenient place to delete it.
+  Task_token* this_blocker = NULL;
+  if (ibase == NULL)
+    {
+      // Normal link.  Queue a Read_symbols task for each input file
+      // on the command line.
+      for (Command_line::const_iterator p = cmdline.begin();
+	   p != cmdline.end();
+	   ++p)
+	{
+	  Task_token* next_blocker = new Task_token(true);
+	  next_blocker->add_blocker();
+	  workqueue->queue(new Read_symbols(input_objects, symtab, layout,
+					    &search_path, 0, mapfile, &*p, NULL,
+					    NULL, this_blocker, next_blocker));
+	  this_blocker = next_blocker;
+	}
+    }
+  else
+    {
+      // Incremental update link.  Process the list of input files
+      // stored in the base file, and queue a task for each file:
+      // a Read_symbols task for a changed file, and an Add_symbols task
+      // for an unchanged file.  We need to mark all the space used by
+      // unchanged files before we can start any tasks running.
+      unsigned int input_file_count = ibase->input_file_count();
+      std::vector<Task*> tasks;
+      tasks.reserve(input_file_count);
+      for (unsigned int i = 0; i < input_file_count; ++i)
+	{
+	  Task_token* next_blocker = new Task_token(true);
+	  next_blocker->add_blocker();
+	  Task* t = process_incremental_input(ibase, i, input_objects, symtab,
+					      layout, &search_path, mapfile,
+					      this_blocker, next_blocker);
+	  tasks.push_back(t);
+	  this_blocker = next_blocker;
+	}
+      // Now we can queue the tasks.
+      for (unsigned int i = 0; i < tasks.size(); i++)
+	workqueue->queue(tasks[i]);
+    }
+
+  if (options.has_plugins())
+    {
+      Task_token* next_blocker = new Task_token(true);
+      next_blocker->add_blocker();
+      workqueue->queue(new Plugin_hook(options, input_objects, symtab, layout,
+				       &search_path, mapfile, this_blocker,
+				       next_blocker));
+      this_blocker = next_blocker;
+    }
+
+  if (options.relocatable()
+      && (options.gc_sections() || options.icf_enabled()))
+    gold_error(_("cannot mix -r with --gc-sections or --icf"));
+
+  if (options.gc_sections() || options.icf_enabled())
+    {
+      workqueue->queue(new Task_function(new Gc_runner(options,
+						       input_objects,
+						       symtab,
+						       layout,
+						       mapfile),
+					 this_blocker,
+					 "Task_function Gc_runner"));
+    }
+  else
+    {
+      workqueue->queue(new Task_function(new Middle_runner(options,
+							   input_objects,
+							   symtab,
+							   layout,
+							   mapfile),
+					 this_blocker,
+					 "Task_function Middle_runner"));
+    }
+}
+
+// Process an incremental input file: if it is unchanged from the previous
+// link, return a task to add its symbols from the base file's incremental
+// info; if it has changed, return a normal Read_symbols task.  We create a
+// task for every input file, if only to report the file for rebuilding the
+// incremental info.
+
+static Task*
+process_incremental_input(Incremental_binary* ibase,
+			  unsigned int input_file_index,
+			  Input_objects* input_objects,
+			  Symbol_table* symtab,
+			  Layout* layout,
+			  Dirsearch* search_path,
+			  Mapfile* mapfile,
+			  Task_token* this_blocker,
+			  Task_token* next_blocker)
+{
+  const Incremental_binary::Input_reader* input_reader =
+      ibase->get_input_reader(input_file_index);
+  Incremental_input_type input_type = input_reader->type();
+
+  // Get the input argument corresponding to this input file, matching on
+  // the argument serial number.  If the input file cannot be matched
+  // to an existing input argument, synthesize a new one.
+  const Input_argument* input_argument =
+      ibase->get_input_argument(input_file_index);
+  if (input_argument == NULL)
+    {
+      Input_file_argument file(input_reader->filename(),
+			       Input_file_argument::INPUT_FILE_TYPE_FILE,
+			       "", false, parameters->options());
+      Input_argument* arg = new Input_argument(file);
+      arg->set_script_info(ibase->get_script_info(input_file_index));
+      input_argument = arg;
+    }
+
+  gold_debug(DEBUG_INCREMENTAL, "Incremental object: %s, type %d",
+	     input_reader->filename(), input_type);
+
+  if (input_type == INCREMENTAL_INPUT_SCRIPT)
+    {
+      // Incremental_binary::check_inputs should have cancelled the
+      // incremental update if the script has changed.
+      gold_assert(!ibase->file_has_changed(input_file_index));
+      return new Check_script(layout, ibase, input_file_index, input_reader,
+			      this_blocker, next_blocker);
+    }
+
+  if (input_type == INCREMENTAL_INPUT_ARCHIVE)
+    {
+      Incremental_library* lib = ibase->get_library(input_file_index);
+      gold_assert(lib != NULL);
+      if (lib->filename() == "/group/"
+	  || !ibase->file_has_changed(input_file_index))
+	{
+	  // Queue a task to check that no references have been added to any
+	  // of the library's unused symbols.
+	  return new Check_library(symtab, layout, ibase, input_file_index,
+				   input_reader, this_blocker, next_blocker);
+	}
+      else
+	{
+	  // Queue a Read_symbols task to process the archive normally.
+	  return new Read_symbols(input_objects, symtab, layout, search_path,
+				  0, mapfile, input_argument, NULL, NULL,
+				  this_blocker, next_blocker);
+	}
+    }
+
+  if (input_type == INCREMENTAL_INPUT_ARCHIVE_MEMBER)
+    {
+      // For archive members, check the timestamp of the containing archive.
+      Incremental_library* lib = ibase->get_library(input_file_index);
+      gold_assert(lib != NULL);
+      // Process members of a --start-lib/--end-lib group as normal objects.
+      if (lib->filename() != "/group/")
+	{
+	  if (ibase->file_has_changed(lib->input_file_index()))
+	    {
+	      return new Read_member(input_objects, symtab, layout, mapfile,
+				     input_reader, this_blocker, next_blocker);
+	    }
+	  else
+	    {
+	      // The previous contributions from this file will be kept.
+	      // Mark the pieces of output sections contributed by this
+	      // object.
+	      ibase->reserve_layout(input_file_index);
+	      Object* obj = make_sized_incremental_object(ibase,
+							  input_file_index,
+							  input_type,
+							  input_reader);
+	      return new Add_symbols(input_objects, symtab, layout,
+				     search_path, 0, mapfile, input_argument,
+				     obj, lib, NULL, this_blocker,
+				     next_blocker);
+	    }
+	}
+    }
+
+  // Normal object file or shared library.  Check if the file has changed
+  // since the last incremental link.
+  if (ibase->file_has_changed(input_file_index))
+    {
+      return new Read_symbols(input_objects, symtab, layout, search_path, 0,
+			      mapfile, input_argument, NULL, NULL,
+			      this_blocker, next_blocker);
+    }
+  else
+    {
+      // The previous contributions from this file will be kept.
+      // Mark the pieces of output sections contributed by this object.
+      ibase->reserve_layout(input_file_index);
+      Object* obj = make_sized_incremental_object(ibase,
+						  input_file_index,
+						  input_type,
+						  input_reader);
+      return new Add_symbols(input_objects, symtab, layout, search_path, 0,
+			     mapfile, input_argument, obj, NULL, NULL,
+			     this_blocker, next_blocker);
+    }
+}
+
+// Queue up a set of tasks to be done before queueing the middle set
+// of tasks.  This is only necessary when garbage collection
+// (--gc-sections) of unused sections is desired.  The relocs are read
+// and processed here early to determine the garbage sections before the
+// relocs can be scanned in later tasks.
+
+void
+queue_middle_gc_tasks(const General_options& options,
+		      const Task* ,
+		      const Input_objects* input_objects,
+		      Symbol_table* symtab,
+		      Layout* layout,
+		      Workqueue* workqueue,
+		      Mapfile* mapfile)
+{
+  // Read_relocs for all the objects must be done and processed to find
+  // unused sections before any scanning of the relocs can take place.
+  Task_token* this_blocker = NULL;
+  for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
+       p != input_objects->relobj_end();
+       ++p)
+    {
+      Task_token* next_blocker = new Task_token(true);
+      next_blocker->add_blocker();
+      workqueue->queue(new Read_relocs(symtab, layout, *p, this_blocker,
+				       next_blocker));
+      this_blocker = next_blocker;
+    }
+
+  // If we are given only archives in input, we have no regular
+  // objects and THIS_BLOCKER is NULL here.  Create a dummy
+  // blocker here so that we can run the middle tasks immediately.
+  if (this_blocker == NULL)
+    {
+      gold_assert(input_objects->number_of_relobjs() == 0);
+      this_blocker = new Task_token(true);
+    }
+
+  workqueue->queue(new Task_function(new Middle_runner(options,
+						       input_objects,
+						       symtab,
+						       layout,
+						       mapfile),
+				     this_blocker,
+				     "Task_function Middle_runner"));
+}
+
+// Queue up the middle set of tasks.  These are the tasks which run
+// after all the input objects have been found and all the symbols
+// have been read, but before we lay out the output file.
+
+void
+queue_middle_tasks(const General_options& options,
+		   const Task* task,
+		   const Input_objects* input_objects,
+		   Symbol_table* symtab,
+		   Layout* layout,
+		   Workqueue* workqueue,
+		   Mapfile* mapfile)
+{
+  Timer* timer = parameters->timer();
+  if (timer != NULL)
+    timer->stamp(0);
+
+  // Add any symbols named with -u options to the symbol table.
+  symtab->add_undefined_symbols_from_command_line(layout);
+
+  // If garbage collection was chosen, relocs have been read and processed
+  // at this point by pre_middle_tasks.  Layout can then be done for all
+  // objects.
+  if (parameters->options().gc_sections())
+    {
+      // Find the start symbol if any.
+      Symbol* sym = symtab->lookup(parameters->entry());
+      if (sym != NULL)
+	symtab->gc_mark_symbol(sym);
+      sym = symtab->lookup(parameters->options().init());
+      if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
+	symtab->gc_mark_symbol(sym);
+      sym = symtab->lookup(parameters->options().fini());
+      if (sym != NULL && sym->is_defined() && !sym->is_from_dynobj())
+	symtab->gc_mark_symbol(sym);
+      // Symbols named with -u should not be considered garbage.
+      symtab->gc_mark_undef_symbols(layout);
+      gold_assert(symtab->gc() != NULL);
+      // Do a transitive closure on all references to determine the worklist.
+      symtab->gc()->do_transitive_closure();
+    }
+
+  // If identical code folding (--icf) is chosen it makes sense to do it
+  // only after garbage collection (--gc-sections) as we do not want to
+  // be folding sections that will be garbage.
+  if (parameters->options().icf_enabled())
+    {
+      symtab->icf()->find_identical_sections(input_objects, symtab);
+    }
+
+  // Call Object::layout for the second time to determine the
+  // output_sections for all referenced input sections.  When
+  // --gc-sections or --icf is turned on, or when certain input
+  // sections have to be mapped to unique segments, Object::layout
+  // is called twice.  It is called the first time when symbols
+  // are added.
+  if (parameters->options().gc_sections()
+      || parameters->options().icf_enabled()
+      || layout->is_unique_segment_for_sections_specified())
+    {
+      for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
+	   p != input_objects->relobj_end();
+	   ++p)
+	{
+	  Task_lock_obj<Object> tlo(task, *p);
+	  (*p)->layout(symtab, layout, NULL);
+	}
+    }
+
+  // Layout deferred objects due to plugins.
+  if (parameters->options().has_plugins())
+    {
+      Plugin_manager* plugins = parameters->options().plugins();
+      gold_assert(plugins != NULL);
+      plugins->layout_deferred_objects();
+    }
+
+  /* If plugins have specified a section order, re-arrange input sections
+     according to a specified section order.  If --section-ordering-file is
+     also specified, do not do anything here.  */
+  if (parameters->options().has_plugins()
+      && layout->is_section_ordering_specified()
+      && !parameters->options().section_ordering_file ())
+    {
+      for (Layout::Section_list::const_iterator p
+	     = layout->section_list().begin();
+	   p != layout->section_list().end();
+	   ++p)
+	(*p)->update_section_layout(layout->get_section_order_map());
+    }
+
+  if (parameters->options().gc_sections()
+      || parameters->options().icf_enabled())
+    {
+      for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
+	   p != input_objects->relobj_end();
+	   ++p)
+	{
+	  // Update the value of output_section stored in rd.
+	  Read_relocs_data* rd = (*p)->get_relocs_data();
+	  for (Read_relocs_data::Relocs_list::iterator q = rd->relocs.begin();
+	       q != rd->relocs.end();
+	       ++q)
+	    {
+	      q->output_section = (*p)->output_section(q->data_shndx);
+	      q->needs_special_offset_handling =
+		      (*p)->is_output_section_offset_invalid(q->data_shndx);
+	    }
+	}
+    }
+
+  // We have to support the case of not seeing any input objects, and
+  // generate an empty file.  Existing builds depend on being able to
+  // pass an empty archive to the linker and get an empty object file
+  // out.  In order to do this we need to use a default target.
+  if (input_objects->number_of_input_objects() == 0
+      && layout->incremental_base() == NULL)
+    parameters_force_valid_target();
+
+  int thread_count = options.thread_count_middle();
+  if (thread_count == 0)
+    thread_count = std::max(2, input_objects->number_of_input_objects());
+  workqueue->set_thread_count(thread_count);
+
+  // Now we have seen all the input files.
+  const bool doing_static_link =
+    (!input_objects->any_dynamic()
+     && !parameters->options().output_is_position_independent());
+  set_parameters_doing_static_link(doing_static_link);
+  if (!doing_static_link && options.is_static())
+    {
+      // We print out just the first .so we see; there may be others.
+      gold_assert(input_objects->dynobj_begin() != input_objects->dynobj_end());
+      gold_error(_("cannot mix -static with dynamic object %s"),
+		 (*input_objects->dynobj_begin())->name().c_str());
+    }
+  if (!doing_static_link && parameters->options().relocatable())
+    gold_fatal(_("cannot mix -r with dynamic object %s"),
+	       (*input_objects->dynobj_begin())->name().c_str());
+  if (!doing_static_link
+      && options.oformat_enum() != General_options::OBJECT_FORMAT_ELF)
+    gold_fatal(_("cannot use non-ELF output format with dynamic object %s"),
+	       (*input_objects->dynobj_begin())->name().c_str());
+
+  if (parameters->options().relocatable())
+    {
+      Input_objects::Relobj_iterator p = input_objects->relobj_begin();
+      if (p != input_objects->relobj_end())
+	{
+	  bool uses_split_stack = (*p)->uses_split_stack();
+	  for (++p; p != input_objects->relobj_end(); ++p)
+	    {
+	      if ((*p)->uses_split_stack() != uses_split_stack)
+		gold_fatal(_("cannot mix split-stack '%s' and "
+			     "non-split-stack '%s' when using -r"),
+			   (*input_objects->relobj_begin())->name().c_str(),
+			   (*p)->name().c_str());
+	    }
+	}
+    }
+
+  // For incremental updates, record the existing GOT and PLT entries,
+  // and the COPY relocations.
+  if (parameters->incremental_update())
+    {
+      Incremental_binary* ibase = layout->incremental_base();
+      ibase->process_got_plt(symtab, layout);
+      ibase->emit_copy_relocs(symtab);
+    }
+
+  if (is_debugging_enabled(DEBUG_SCRIPT))
+    layout->script_options()->print(stderr);
+
+  // For each dynamic object, record whether we've seen all the
+  // dynamic objects that it depends upon.
+  input_objects->check_dynamic_dependencies();
+
+  // Do the --no-undefined-version check.
+  if (!parameters->options().undefined_version())
+    {
+      Script_options* so = layout->script_options();
+      so->version_script_info()->check_unmatched_names(symtab);
+    }
+
+  // Create any automatic note sections.
+  layout->create_notes();
+
+  // Create any output sections required by any linker script.
+  layout->create_script_sections();
+
+  // Define some sections and symbols needed for a dynamic link.  This
+  // handles some cases we want to see before we read the relocs.
+  layout->create_initial_dynamic_sections(symtab);
+
+  // Define symbols from any linker scripts.
+  layout->define_script_symbols(symtab);
+
+  // TODO(csilvers): figure out a more principled way to get the target
+  Target* target = const_cast<Target*>(&parameters->target());
+
+  // Attach sections to segments.
+  layout->attach_sections_to_segments(target);
+
+  if (!parameters->options().relocatable())
+    {
+      // Predefine standard symbols.
+      define_standard_symbols(symtab, layout);
+
+      // Define __start and __stop symbols for output sections where
+      // appropriate.
+      layout->define_section_symbols(symtab);
+
+      // Define target-specific symbols.
+      target->define_standard_symbols(symtab, layout);
+    }
+
+  // Make sure we have symbols for any required group signatures.
+  layout->define_group_signatures(symtab);
+
+  Task_token* this_blocker = NULL;
+
+  // Allocate common symbols.  We use a blocker to run this before the
+  // Scan_relocs tasks, because it writes to the symbol table just as
+  // they do.
+  if (parameters->options().define_common())
+    {
+      this_blocker = new Task_token(true);
+      this_blocker->add_blocker();
+      workqueue->queue(new Allocate_commons_task(symtab, layout, mapfile,
+						 this_blocker));
+    }
+
+  // If doing garbage collection, the relocations have already been read.
+  // Otherwise, read and scan the relocations.
+  if (parameters->options().gc_sections()
+      || parameters->options().icf_enabled())
+    {
+      for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
+	   p != input_objects->relobj_end();
+	   ++p)
+	{
+	  Task_token* next_blocker = new Task_token(true);
+	  next_blocker->add_blocker();
+	  workqueue->queue(new Scan_relocs(symtab, layout, *p,
+					   (*p)->get_relocs_data(),
+					   this_blocker, next_blocker));
+	  this_blocker = next_blocker;
+	}
+    }
+  else
+    {
+      // Read the relocations of the input files.  We do this to find
+      // which symbols are used by relocations which require a GOT and/or
+      // a PLT entry, or a COPY reloc.  When we implement garbage
+      // collection we will do it here by reading the relocations in a
+      // breadth first search by references.
+      //
+      // We could also read the relocations during the first pass, and
+      // mark symbols at that time.  That is how the old GNU linker works.
+      // Doing that is more complex, since we may later decide to discard
+      // some of the sections, and thus change our minds about the types
+      // of references made to the symbols.
+      for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
+	   p != input_objects->relobj_end();
+	   ++p)
+	{
+	  Task_token* next_blocker = new Task_token(true);
+	  next_blocker->add_blocker();
+	  workqueue->queue(new Read_relocs(symtab, layout, *p, this_blocker,
+					   next_blocker));
+	  this_blocker = next_blocker;
+	}
+    }
+
+  if (this_blocker == NULL)
+    {
+      if (input_objects->number_of_relobjs() == 0)
+	{
+	  // If we are given only archives in input, we have no regular
+	  // objects and THIS_BLOCKER is NULL here.  Create a dummy
+	  // blocker here so that we can run the layout task immediately.
+	  this_blocker = new Task_token(true);
+	}
+      else
+	{
+	  // If we failed to open any input files, it's possible for
+	  // THIS_BLOCKER to be NULL here.  There's no real point in
+	  // continuing if that happens.
+	  gold_assert(parameters->errors()->error_count() > 0);
+	  gold_exit(GOLD_ERR);
+	}
+    }
+
+  // When all those tasks are complete, we can start laying out the
+  // output file.
+  workqueue->queue(new Task_function(new Layout_task_runner(options,
+							    input_objects,
+							    symtab,
+							    target,
+							    layout,
+							    mapfile),
+				     this_blocker,
+				     "Task_function Layout_task_runner"));
+}
+
+// Queue up the final set of tasks.  This is called at the end of
+// Layout_task.
+
+void
+queue_final_tasks(const General_options& options,
+		  const Input_objects* input_objects,
+		  const Symbol_table* symtab,
+		  Layout* layout,
+		  Workqueue* workqueue,
+		  Output_file* of)
+{
+  Timer* timer = parameters->timer();
+  if (timer != NULL)
+    timer->stamp(1);
+
+  int thread_count = options.thread_count_final();
+  if (thread_count == 0)
+    thread_count = std::max(2, input_objects->number_of_input_objects());
+  workqueue->set_thread_count(thread_count);
+
+  bool any_postprocessing_sections = layout->any_postprocessing_sections();
+
+  // Use a blocker to wait until all the input sections have been
+  // written out.
+  Task_token* input_sections_blocker = NULL;
+  if (!any_postprocessing_sections)
+    {
+      input_sections_blocker = new Task_token(true);
+      input_sections_blocker->add_blockers(input_objects->number_of_relobjs());
+    }
+
+  // Use a blocker to block any objects which have to wait for the
+  // output sections to complete before they can apply relocations.
+  Task_token* output_sections_blocker = new Task_token(true);
+  output_sections_blocker->add_blocker();
+
+  // Use a blocker to block the final cleanup task.
+  Task_token* final_blocker = new Task_token(true);
+  // Write_symbols_task, Write_sections_task, Write_data_task,
+  // Relocate_tasks.
+  final_blocker->add_blockers(3);
+  final_blocker->add_blockers(input_objects->number_of_relobjs());
+  if (!any_postprocessing_sections)
+    final_blocker->add_blocker();
+
+  // Queue a task to write out the symbol table.
+  workqueue->queue(new Write_symbols_task(layout,
+					  symtab,
+					  input_objects,
+					  layout->sympool(),
+					  layout->dynpool(),
+					  of,
+					  final_blocker));
+
+  // Queue a task to write out the output sections.
+  workqueue->queue(new Write_sections_task(layout, of, output_sections_blocker,
+					   final_blocker));
+
+  // Queue a task to write out everything else.
+  workqueue->queue(new Write_data_task(layout, symtab, of, final_blocker));
+
+  // Queue a task for each input object to relocate the sections and
+  // write out the local symbols.
+  for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();
+       p != input_objects->relobj_end();
+       ++p)
+    workqueue->queue(new Relocate_task(symtab, layout, *p, of,
+				       input_sections_blocker,
+				       output_sections_blocker,
+				       final_blocker));
+
+  // Queue a task to write out the output sections which depend on
+  // input sections.  If there are any sections which require
+  // postprocessing, then we need to do this last, since it may resize
+  // the output file.
+  if (!any_postprocessing_sections)
+    {
+      Task* t = new Write_after_input_sections_task(layout, of,
+						    input_sections_blocker,
+						    final_blocker);
+      workqueue->queue(t);
+    }
+  else
+    {
+      Task_token* new_final_blocker = new Task_token(true);
+      new_final_blocker->add_blocker();
+      Task* t = new Write_after_input_sections_task(layout, of,
+						    final_blocker,
+						    new_final_blocker);
+      workqueue->queue(t);
+      final_blocker = new_final_blocker;
+    }
+
+  // Create tasks for tree-style build ID computation, if necessary.
+  final_blocker = layout->queue_build_id_tasks(workqueue, final_blocker, of);
+
+  // Queue a task to close the output file.  This will be blocked by
+  // FINAL_BLOCKER.
+  workqueue->queue(new Task_function(new Close_task_runner(&options, layout,
+							   of),
+				     final_blocker,
+				     "Task_function Close_task_runner"));
+}
+
+} // End namespace gold.