* archive.cc (Archive::include_member): Adjust call to

	report_object.
	(Add_archive_symbols::run): Track argument serial numbers.
	(Lib_group::include_member): Likewise.
	(Add_lib_group_symbols::run): Adjust call to report_archive_begin.
	* archive.h (Incremental_archive_entry::Archive_member):
	Initialize arg_serial_.
	(Archive_member::arg_serial_): New data member.
	* dynobj.cc (Dynobj::Dynobj): Allow input_file_ to be NULL.
	(Sized_dynobj::do_add_symbols): Track symbols when doing an
	incremental link.
	(Sized_dynobj::do_for_all_local_got_entries): New function.
	* dynobj.h: (Sized_dynobj::do_for_all_local_got_entries): New
	function.
	* fileread.cc (get_mtime): New function.
	* fileread.h (get_mtime): New function.
	* gold.cc (queue_initial_tasks): Check for incremental update.
	(process_incremental_input): New function.
	(queue_middle_tasks): Don't force valid target for incremental
	update.
	* incremental-dump.cc (find_input_containing_global): Adjust
	size of symbol info entry.
	(dump_incremental_inputs): Dump argument serial number and
	in_system_directory flag; bias shndx by 1; print symbol names
	when dumping per-file symbol lists; use new symbol info readers.
	* incremental.cc
	(Output_section_incremental_inputs:update_data_size): New function.
	(Sized_incremental_binary::setup_readers): Setup input readers
	for each input file; build maps for files added from libraries
	and scripts.
	(Sized_incremental_binary::check_input_args): New function.
	(Sized_incremental_binary::do_check_inputs): Build map of argument
	serial numbers to input arguments.
	(Sized_incremental_binary::do_file_has_changed): Rename
	do_file_is_unchanged to this; compare file modification times.
	(Sized_incremental_binary::do_init_layout): New function.
	(Sized_incremental_binary::do_reserve_layout): New function.
	(Sized_incremental_binary::do_get_input_reader): Remove.
	(Sized_incremental_binary::get_symtab_view): New function.
	(Incremental_checker::can_incrementally_link_output_file): Remove.
	(Incremental_inputs::report_command_line): Exclude --debug options.
	(Incremental_inputs::report_archive_begin): Add parameter; track
	argument serial numbers; don't put input file entry for archive
	before archive members.
	(Incremental_inputs::report_archive_end): Put input file entry
	for archive after archive members.
	(Incremental_inputs::report_object): Add parameter; track argument
	serial numbers and in_system_directory flag.
	(Incremental_inputs::report_script): Add parameter; track argument
	serial numbers.
	(Output_section_incremental_inputs::set_final_data_size): Adjust
	size of symbol info entry; check for forwarding symbols.
	(Output_section_incremental_inputs::write_input_files): Write
	in_system_directory flag and argument serial number.
	(Output_section_incremental_inputs::write_info_blocks): Map section
	indices between incremental info and original input file; store
	input section index for each symbol.
	(class Local_got_offset_visitor): Derive from Got_offset_list::Visitor;
	change operator() to visit().
	(class Global_got_offset_visitor): Likewise.
	(class Global_symbol_visitor_got_plt):
	(Output_section_incremental_inputs::write_got_plt): Use new visitor
	classes.
	(Sized_incr_relobj::Sized_incr_relobj): New constructor.
	(Sized_incr_relobj::do_read_symbols): New function.
	(Sized_incr_relobj::do_layout): New function.
	(Sized_incr_relobj::do_layout_deferred_sections): New function.
	(Sized_incr_relobj::do_add_symbols): New function.
	(Sized_incr_relobj::do_should_include_member): New function.
	(Sized_incr_relobj::do_for_all_global_symbols): New function.
	(Sized_incr_relobj::do_for_all_local_got_entries): New function.
	(Sized_incr_relobj::do_section_size): New function.
	(Sized_incr_relobj::do_section_name): New function.
	(Sized_incr_relobj::do_section_contents): New function.
	(Sized_incr_relobj::do_section_flags): New function.
	(Sized_incr_relobj::do_section_entsize): New function.
	(Sized_incr_relobj::do_section_address): New function.
	(Sized_incr_relobj::do_section_type): New function.
	(Sized_incr_relobj::do_section_link): New function.
	(Sized_incr_relobj::do_section_info): New function.
	(Sized_incr_relobj::do_section_addralign): New function.
	(Sized_incr_relobj::do_initialize_xindex): New function.
	(Sized_incr_relobj::do_get_global_symbol_counts): New function.
	(Sized_incr_relobj::do_read_relocs): New function.
	(Sized_incr_relobj::do_gc_process_relocs): New function.
	(Sized_incr_relobj::do_scan_relocs): New function.
	(Sized_incr_relobj::do_count_local_symbols): New function.
	(Sized_incr_relobj::do_finalize_local_symbols): New function.
	(Sized_incr_relobj::do_set_local_dynsym_indexes): New function.
	(Sized_incr_relobj::do_set_local_dynsym_offset): New function.
	(Sized_incr_relobj::do_relocate): New function.
	(Sized_incr_relobj::do_set_section_offset): New function.
	(Sized_incr_dynobj::Sized_incr_dynobj): New function.
	(Sized_incr_dynobj::do_read_symbols): New function.
	(Sized_incr_dynobj::do_layout): New function.
	(Sized_incr_dynobj::do_add_symbols): New function.
	(Sized_incr_dynobj::do_should_include_member): New function.
	(Sized_incr_dynobj::do_for_all_global_symbols): New function.
	(Sized_incr_dynobj::do_for_all_local_got_entries): New function.
	(Sized_incr_dynobj::do_section_size): New function.
	(Sized_incr_dynobj::do_section_name): New function.
	(Sized_incr_dynobj::do_section_contents): New function.
	(Sized_incr_dynobj::do_section_flags): New function.
	(Sized_incr_dynobj::do_section_entsize): New function.
	(Sized_incr_dynobj::do_section_address): New function.
	(Sized_incr_dynobj::do_section_type): New function.
	(Sized_incr_dynobj::do_section_link): New function.
	(Sized_incr_dynobj::do_section_info): New function.
	(Sized_incr_dynobj::do_section_addralign): New function.
	(Sized_incr_dynobj::do_initialize_xindex): New function.
	(Sized_incr_dynobj::do_get_global_symbol_counts): New function.
	(make_sized_incremental_object): New function.
	(Incremental_library::copy_unused_symbols): New function.
	(Incremental_library::do_for_all_unused_symbols): New function.
	* incremental.h (enum Incremental_input_flags): New type.
	(class Incremental_checker): Remove.
	(Incremental_input_entry::Incremental_input_entry): Add argument
	serial number.
	(Incremental_input_entry::arg_serial): New function.
	(Incremental_input_entry::set_is_in_system_directory): New function.
	(Incremental_input_entry::is_in_system_directory): New function.
	(Incremental_input_entry::arg_serial_): New data member.
	(Incremental_input_entry::is_in_system_directory_): New data member.
	(class Script_info): Move here from script.h.
	(Script_info::Script_info): Add filename parameter.
	(Script_info::filename): New function.
	(Script_info::filename_): New data member.
	(Incremental_script_entry::Incremental_script_entry): Add argument
	serial number.
	(Incremental_object_entry::Incremental_object_entry): Likewise.
	(Incremental_object_entry::add_input_section): Build list of input
	sections with map to original shndx.
	(Incremental_object_entry::get_input_section_index): New function.
	(Incremental_object_entry::shndx_): New data member.
	(Incremental_object_entry::name_key_): Rename; adjust all refs.
	(Incremental_object_entry::sh_size_): Rename; adjust all refs.
	(Incremental_archive_entry::Incremental_archive_entry): Add argument
	serial number.
	(Incremental_inputs::report_archive_begin): Likewise.
	(Incremental_inputs::report_object): Likewise.
	(Incremental_inputs::report_script): Likewise.
	(class Incremental_global_symbol_reader): New class.
	(Incremental_input_entry_reader::Incremental_input_entry_reader): Read
	and store flags and input file type.
	(Incremental_input_entry_reader::arg_serial): New function.
	(Incremental_input_entry_reader::type): Extract type from flags.
	(Incremental_input_entry_reader::is_in_system_directory): New function.
	(Incremental_input_entry_reader::get_input_section_count): Call
	accessor function for type.
	(Incremental_input_entry_reader::get_symbol_offset): Call accessor
	function for type; adjust size of global symbol entry.
	(Incremental_input_entry_reader::get_global_symbol_count): Call
	accessor function for type.
	(Incremental_input_entry_reader::get_object_count): Likewise.
	(Incremental_input_entry_reader::get_object_offset): Likewise.
	(Incremental_input_entry_reader::get_member_count): Likewise.
	(Incremental_input_entry_reader::get_unused_symbol_count): Likewise.
	(Incremental_input_entry_reader::get_member_offset): Likewise.
	(Incremental_input_entry_reader::get_unused_symbol): Likewise.
	(Incremental_input_entry_reader::Global_symbol_info): Remove.
	(Incremental_input_entry_reader::get_global_symbol_info): Remove.
	(Incremental_input_entry_reader::get_global_symbol_reader): New
	function.
	(Incremental_input_entry_reader::get_output_symbol_index): New
	function.
	(Incremental_input_entry_reader::type_): Remove.
	(Incremental_input_entry_reader::flags_): New data member.
	(Incremental_inputs_reader::input_file_offset): New function.
	(Incremental_inputs_reader::input_file_index): New function.
	(Incremental_inputs_reader::input_file): Call input_file_offset.
	(Incremental_inputs_reader::input_file_at_offset): New function.
	(Incremental_relocs_reader::get_r_type): Reformat.
	(Incremental_relocs_reader::get_r_shndx): Reformat.
	(Incremental_relocs_reader::get_r_offset): Reformat.
	(Incremental_relocs_reader::data): New function.
	(Incremental_binary::Incremental_binary): Initialize new data members.
	(Incremental_binary::check_inputs): Add cmdline parameter.
	(Incremental_binary::file_is_unchanged): Remove.
	(Input_reader::arg_serial): New function.
	(Input_reader::get_unused_symbol_count): New function.
	(Input_reader::get_unused_symbol): New function.
	(Input_reader::do_arg_serial): New function.
	(Input_reader::do_get_unused_symbol_count): New function.
	(Input_reader::do_get_unused_symbol): New function.
	(Incremental_binary::input_file_count): New function.
	(Incremental_binary::get_input_reader): Change signature to use
	index instead of filename.
	(Incremental_binary::file_has_changed): New function.
	(Incremental_binary::get_input_argument): New function.
	(Incremental_binary::get_library): New function.
	(Incremental_binary::get_script_info): New function.
	(Incremental_binary::init_layout): New function.
	(Incremental_binary::reserve_layout): New function.
	(Incremental_binary::output_file): New function.
	(Incremental_binary::do_check_inputs): New function.
	(Incremental_binary::do_file_is_unchanged): Remove.
	(Incremental_binary::do_file_has_changed): New function.
	(Incremental_binary::do_init_layout): New function.
	(Incremental_binary::do_reserve_layout): New function.
	(Incremental_binary::do_input_file_count): New function.
	(Incremental_binary::do_get_input_reader): Change signature.
	(Incremental_binary::input_args_map_): New data member.
	(Incremental_binary::library_map_): New data member.
	(Incremental_binary::script_map_): New data member.
	(Sized_incremental_binary::Sized_incremental_binary): Initialize
	new data members.
	(Sized_incremental_binary::output_section): New function.
	(Sized_incremental_binary::inputs_reader): Add const.
	(Sized_incremental_binary::symtab_reader): Add const.
	(Sized_incremental_binary::relocs_reader): Add const.
	(Sized_incremental_binary::got_plt_reader): Add const.
	(Sized_incremental_binary::get_symtab_view): New function.
	(Sized_incremental_binary::Inputs_reader): New typedef.
	(Sized_incremental_binary::Input_entry_reader): New typedef.
	(Sized_incremental_binary::do_check_inputs): Add cmdline parameter.
	(Sized_incremental_binary::do_file_is_unchanged): Remove.
	(Sized_incremental_binary::do_file_has_changed): New function.
	(Sized_incremental_binary::do_init_layout): New function.
	(Sized_incremental_binary::do_reserve_layout): New function.
	(Sized_input_reader::Inputs_reader): Remove.
	(Sized_input_reader::Input_entry_reader): Remove.
	(Sized_input_reader::do_arg_serial): New function.
	(Sized_input_reader::do_get_unused_symbol_count): New function.
	(Sized_input_reader::do_get_unused_symbol): New function.
	(Sized_incremental_binary::do_input_file_count): New function.
	(Sized_incremental_binary::do_get_input_reader): Change signature;
	use index instead of filename.
	(Sized_incremental_binary::section_map_): New data member.
	(Sized_incremental_binary::input_entry_readers_): New data member.
	(class Sized_incr_relobj): New class.
	(class Sized_incr_dynobj): New class.
	(make_sized_incremental_object): New function.
	(class Incremental_library): New class.
	* layout.cc (Free_list::num_lists): New static data member.
	(Free_list::num_nodes): New static data member.
	(Free_list::num_removes): New static data member.
	(Free_list::num_remove_visits): New static data member.
	(Free_list::num_allocates): New static data member.
	(Free_list::num_allocate_visits): New static data member.
	(Free_list::init): New function.
	(Free_list::remove): New function.
	(Free_list::allocate): New function.
	(Free_list::dump): New function.
	(Free_list::print_stats): New function.
	(Layout_task_runner::run): Resize output file for incremental updates.
	(Layout::Layout): Initialize new data members.
	(Layout::set_incremental_base): New function.
	(Layout::init_fixed_output_section): New function.
	(Layout::layout_eh_frame): Do not build .eh_frame_hdr section for
	incremental updates.
	(Layout::create_gold_note): Do not create gold note section for
	incremental updates.
	(Layout::set_segment_offsets): Do not recalculate RELRO alignment
	for incremental updates.
	(Layout::set_section_offsets): For incremental updates, allocate space
	from free list.
	(Layout::create_symtab_sections): Layout with offsets relative to
	start of section; for incremental updates, allocate space from free
	list.
	(Layout::create_shdrs): For incremental updates, allocate space from
	free list.
	(Layout::finish_dynamic_section): For incremental updates, do not
	check --as-needed (fixed in subsequent patch).
	* layout.h (class Free_list): New class.
	(Layout::set_incremental_base): New function.
	(Layout::incremental_base): New function.
	(Layout::init_fixed_output_section): New function.
	(Layout::allocate): New function.
	(Layout::incremental_base_): New data member.
	(Layout::free_list_): New data member.
	* main.cc (main): Print Free_list statistics.
	* object.cc (Relobj::finalize_incremental_relocs): Add
	clear_counts parameter; clear counts only when clear_counts is set.
	(Sized_relobj::Sized_relobj): Initialize new base class.
	(Sized_relobj::do_layout): Don't report special sections.
	(Sized_relobj::do_for_all_local_got_entries): New function.
	(Sized_relobj::write_local_symbols): Add symtab_off parameter; add
	symtab_off to all symbol table offsets.
	(Sized_relobj::do_get_global_symbol_counts): Add typename keyword.
	* object.h (class Got_offset_list): Move to top of file.
	(Object::Object): Allow case where input_file == NULL.
	(Object::~Object): Likewise.
	(Object::input_file): Assert that input_file != NULL.
	(Object::lock): Allow case where input_file == NULL.
	(Object::unlock): Likewise.
	(Object::is_locked): Likewise.
	(Object::token): Likewise.
	(Object::release): Likewise.
	(Object::is_incremental): New function.
	(Object::get_mtime): New function.
	(Object::for_all_local_got_entries): New function.
	(Object::clear_view_cache_marks): Allow case where input_file == NULL.
	(Object::set_is_in_system_directory): New function.
	(Object::is_in_system_directory): New function.
	(Object::do_is_incremental): New function.
	(Object::do_get_mtime): New function.
	(Object::do_for_all_local_got_entries): New function.
	(Object::is_in_system_directory_): New data member.
	(Relobj::finalize_incremental_relocs): Add clear_counts parameter.
	(class Sized_relobj_base): New class.
	(class Sized_relobj): Derive from Sized_relobj_base.
	(class Sized_relobj::Symbols): Redeclare from base class.
	(class Sized_relobj::local_got_offset_list): Remove.
	(class Sized_relobj::Output_sections): Redeclare from base class.
	(class Sized_relobj::do_for_all_local_got_entries): New function.
	(class Sized_relobj::write_local_symbols): Add offset parameter.
	(class Sized_relobj::local_symbol_offset_): Update comment.
	(class Sized_relobj::local_dynsym_offset_): Update comment.
	* options.cc (Input_arguments::add_file): Remove const.
	* options.h (Input_file_argument::Input_file_argument):
	Initialize arg_serial_ (all constructors).
	(Input_file_argument::set_arg_serial): New function.
	(Input_file_argument::arg_serial): New function.
	(Input_file_argument::arg_serial_): New data member.
	(Input_arguments::Input_arguments): Initialize file_count_.
	(Input_arguments::add_file): Remove const.
	(Input_arguments::number_of_input_files): New function.
	(Input_arguments::file_count_): New data member.
	(Command_line::number_of_input_files): Call
	Input_arguments::number_of_input_files.
	* output.cc (Output_segment_headers::Output_segment_headers):
	Set current size.
	(Output_section::Input_section::current_data_size): New function.
	(Output_section::Output_section): Initialize new data members.
	(Output_section::add_input_section): Don't do merge sections for
	an incremental link; allocate space from free list for an
	incremental update.
	(Output_section::add_output_section_data): Allocate space from
	free list for an incremental update.
	(Output_section::update_data_size): New function.
	(Output_section::set_fixed_layout): New function.
	(Output_section::reserve): New function.
	(Output_segment::set_section_addresses): Remove const.
	(Output_segment::set_section_list_addresses): Remove const; allocate
	space from free list for an incremental update.
	(Output_segment::set_offset): Adjust size of RELRO segment for an
	incremental update.
	* output.h (Output_data::current_data_size): Move here from
	child classes.
	(Output_data::pre_finalize_data_size): New function.
	(Output_data::update_data_size): New function.
	(Output_section_headers::update_data_size): new function.
	(Output_section_data_build::current_data_size): Move to Output_data.
	(Output_data_strtab::update_data_size): New function.
	(Output_section::current_data_size): Move to Output_data.
	(Output_section::set_fixed_layout): New function.
	(Output_section::has_fixed_layout): New function.
	(Output_section::reserve): New function.
	(Output_section::update_data_size): New function.
	(Output_section::has_fixed_layout_): New data member.
	(Output_section::free_list_): New data member.
	(Output_segment::set_section_addresses): Remove const.
	(Output_segment::set_section_list_addresses): Remove const.
	* plugin.cc (Sized_pluginobj::do_for_all_local_got_entries):
	New function.
	* plugin.h (Sized_pluginobj::do_for_all_local_got_entries):
	New function.
	* readsyms.cc (Read_symbols::do_read_symbols): Add library
	parameter when calling Add_symbols constructor; store argument
	serial number for members of a lib group.
	(Add_symbols::locks): Allow case where token == NULL.
	(Add_symbols::run): Report libraries denoted by --start-lib/--end-lib.
	(Read_member::~Read_member): New function.
	(Read_member::is_runnable): New function.
	(Read_member::locks): New function.
	(Read_member::run): New function.
	(Check_script::~Check_script): New function.
	(Check_script::is_runnable): New function.
	(Check_script::locks): New function.
	(Check_script::run): New function.
	(Check_library::~Check_library): New function.
	(Check_library::is_runnable): New function.
	(Check_library::locks): New function.
	(Check_library::run): New function.
	* readsyms.h (Add_symbols::Add_symbols): Add library parameter.
	(Add_symbols::library_): New data member.
	(class Read_member): New class.
	(class Check_script): New class.
	(class Check_library): New class.
	* reloc.cc (Read_relocs::is_runnable): Allow case where
	token == NULL.
	(Read_relocs::locks): Likewise.
	(Scan_relocs::locks): Likewise.
	(Relocate_task::locks): Likewise.
	(Sized_relobj::do_scan_relocs): Tell finalize_incremental_relocs
	to clear counters.
	(Sized_relobj::incremental_relocs_scan): Fix comment.
	(Sized_relobj::do_relocate): Pass output file offset to
	write_local_symbols.
	(Sized_relobj::incremental_relocs_write_reltype): Use reloc_size
	from class declaration.
	* script.cc (read_input_script): Allocate Script_info; pass
	argument serial number to report_script.
	* script.h (class Script_info): Move to incremental.h.
	* symtab.cc (Symbol_table::add_from_incrobj): New function.
	* symtab.h (Symbol_table::add_from_incrobj): New function.
	(Symbol_table::set_file_offset): New function.

1 files changed, 215 insertions, 26 deletions

diff --git a/gold/gold.cc b/gold/gold.cc
index 564ca39..926e5fb 100644
--- a/gold/gold.cc
+++ b/gold/gold.cc
@@ -48,8 +48,15 @@
 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(bool status)
 {
@@ -178,19 +185,50 @@ queue_initial_tasks(const General_options& options,
     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())
     {
-      Incremental_checker incremental_checker(
-          parameters->options().output_file_name(),
-          layout->incremental_inputs());
-      if (incremental_checker.can_incrementally_link_output_file())
-        {
-          // TODO: remove when incremental linking implemented.
-          printf("Incremental linking might be possible "
-              "(not implemented yet)\n");
-        }
-      // TODO: If we decide on an incremental build, fewer tasks
-      // should be scheduled.
+      if (options.relocatable())
+	gold_error(_("incremental linking is incompatible with -r"));
+      if (options.emit_relocs())
+	gold_error(_("incremental linking is incompatible with --emit-relocs"));
+      if (options.gc_sections())
+	gold_error(_("incremental linking is incompatible with --gc-sections"));
+      if (options.icf_enabled())
+	gold_error(_("incremental linking is incompatible with --icf"));
+      if (options.has_plugins())
+	gold_error(_("incremental linking is incompatible with --plugin"));
+
+      if (parameters->incremental_update())
+	{
+	  Output_file* of = new Output_file(options.output_file_name());
+	  if (!of->open_for_modification())
+	    gold_info(_("incremental update not possible: "
+			"cannot open %s"),
+		      options.output_file_name());
+	  else
+	    {
+	      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_fatal(_("restart link with --incremental-full"));
+	    }
+	}
     }
 
   // Read the input files.  We have to add the symbols to the symbol
@@ -198,16 +236,45 @@ queue_initial_tasks(const General_options& options,
   // 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;
-  for (Command_line::const_iterator p = cmdline.begin();
-       p != cmdline.end();
-       ++p)
+  if (ibase == NULL)
     {
-      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;
+      // 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())
@@ -220,13 +287,11 @@ queue_initial_tasks(const General_options& options,
       this_blocker = next_blocker;
     }
 
-  if (parameters->options().relocatable()
-      && (parameters->options().gc_sections()
-	  || parameters->options().icf_enabled()))
+  if (options.relocatable()
+      && (options.gc_sections() || options.icf_enabled()))
     gold_error(_("cannot mix -r with --gc-sections or --icf"));
 
-  if (parameters->options().gc_sections()
-      || parameters->options().icf_enabled())
+  if (options.gc_sections() || options.icf_enabled())
     {
       workqueue->queue(new Task_function(new Gc_runner(options,
 						       input_objects,
@@ -248,6 +313,129 @@ queue_initial_tasks(const General_options& options,
     }
 }
 
+// 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
@@ -396,7 +584,8 @@ queue_middle_tasks(const General_options& options,
   // 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)
+  if (input_objects->number_of_input_objects() == 0
+      && layout->incremental_base() == NULL)
     parameters_force_valid_target();
 
   int thread_count = options.thread_count_middle();