* Makefile.am (CCFILES): Add gc.cc.
(HFILES): Add gc.h.
* Makefile.in: Regenerate.
* gold.cc (Gc_runner): New class.
(queue_initial_tasks): Call garbage collection related tasks
when corresponding options are invoked.
(queue_middle_gc_tasks): New function.
(queue_middle_tasks): Reorder tasks to allow relocs to be read and
processed early before laying out sections during garbage collection.
* gold.h (queue_middle_gc_tasks): New function.
(is_prefix_of): Move from "layout.cc".
* i386.cc (Target_i386::gc_process_relocs): New function.
* layout.cc (is_prefix_of): Remove. Move to "gold.h"
* main.cc (main): Create object of class "Garbage_collection".
* object.cc (Relobj::copy_symbols_data): New function.
(Relobj::is_section_name_included): New function.
(Sized_relobj::do_layout): Allow this function to be called twice
during garbage collection and defer layout of section during the
first call.
* object.h (Relobj::get_symbols_data): New function.
(Relobj::is_section_name_included): New function.
(Relobj::copy_symbols_data): New function.
(Relobj::set_symbols_data): New function.
(Relobj::get_relocs_data): New function.
(Relobj::set_relocs_data): New function.
(Relobj::is_output_section_offset_invalid): New pure virtual function.
(Relobj::gc_process_relocs): New function.
(Relobj::do_gc_process_relocs): New pure virtual function.
(Relobj::sd_): New data member.
(Sized_relobj::is_output_section_offset_invalid): New function.
(Sized_relobj::do_gc_process_relocs): New function.
* options.h (General_options::gc_sections): Modify to not be a no-op.
(General_options::print_gc_sections): New option.
* plugin.cc (Plugin_finish::run): Remove function call to
Plugin_manager::layout_deferred_objects. Move it to "gold.cc".
* powerpc.cc (Target_powerpc::gc_process_relocs): New function.
* reloc.cc (Read_relocs::run): Add task to process relocs and
determine unreferenced sections when doing garbage collection.
(Gc_process_relocs): New class.
(Sized_relobj::do_gc_process_relocs): New function.
(Sized_relobj::do_scan_relocs): Don't try to scan the relocs for
sections that are garbage collected.
* reloc.h (Gc_process_relocs): New class.
* sparc.cc (Target_sparc::gc_process_relocs): New function.
* symtab.cc (Symbol::should_add_dynsym_entry): Do not add entries for
symbols whose corresponding sections are garbage collected.
(Symbol_table::Symbol_table): Add new parameter for the garbage
collection object.
(Symbol_table::gc_mark_undef_symbols): New function.
(Symbol_table::gc_mark_symbol_for_shlib): New function.
(Symbol_table::gc_mark_dyn_syms): New function.
(Symbol_table::resolve): Do not treat symbols seen in dynamic objects
as garbage.
(Symbol_table::add_from_object): Likewise.
(Symbol_table::add_from_relobj): When building shared objects, do not
treat externally visible symbols as garbage.
(Symbol_table::sized_finalize_symbol): Do not check dynamic symbol
table information for static and relocatable links.
* symtab.h (Symbol_table::set_gc): New function.
(Symbol_table::gc): New function.
(Symbol_table::gc_mark_undef_symbols): New function.
(Symbol_table::gc_mark_symbol_for_shlib): New function.
(Symbol_table::gc_mark_dyn_syms): New function.
(Symbol_table::gc_): New data member.
* target.h (Sized_target::gc_process_relocs): New pure virtual
function.
* x86_64.cc (Target_x86_64::gc_process_relocs): New function.
* testsuite/testfile.cc (Target_test::gc_process_relocs): New function.
* plugin.cc (Plugin_manager::finish): Rename as
layout_deferred_objects. Move cleanup to separate function.
(Plugin_manager::cleanup): New function.
(Plugin_finish::run): Call layout_deferred_objects and cleanup
separately.
* plugin.h (Plugin_manager::finish): Rename as
layout_deferred_objects.
(Plugin_manager::cleanup): New function.
(Plugin_manager::cleanup_done): New field.
include/:
* plugin-api.h: New file.
gold/:
* configure.ac (plugins): Add --enable-plugins option.
* configure: Regenerate.
* config.in: Regenerate.
* Makefile.am (LIBDL): New variable.
(CCFILES): Add plugin.cc.
(HFILES): Add plugin.h.
(ldadd_var): Add LIBDL.
* Makefile.in: Regenerate.
* archive.cc: Include "plugin.h".
(Archive::setup): Don't preread archive symbols when using a plugin.
(Archive::get_file_and_offset): Add memsize parameter. Change callers.
(Archive::get_elf_object_for_member): Call plugin hooks for claiming
files.
(Archive::include_member): Add symbols from plugin objects.
* archive.h (Archive::get_file_and_offset): Add memsize parameter.
* descriptors.cc (Descriptors::open): Check for file descriptors
abandoned by plugins.
(Descriptors::claim_for_plugin): New function.
* descriptors.h (Descriptors::claim_for_plugin): New function.
(Open_descriptor::is_claimed): New field.
(claim_descriptor_for_plugin): New function.
* fileread.cc (File_read::claim_for_plugin): New function.
* fileread.h (File_read::claim_for_plugin): New function.
(File_read::descriptor): New function.
* gold.cc: Include "plugin.h".
(queue_initial_tasks): Add task to call plugin hooks for generating
new object files.
* main.cc: Include "plugin.h".
(main): Load plugin libraries.
* object.h (Pluginobj): Declare.
(Object::pluginobj): New function.
(Object::do_pluginobj): New function.
(Object::set_target): New function.
* options.cc: Include "plugin.h".
(General_options::parse_plugin): New function.
(General_options::General_options): Initialize plugins_ field.
(General_options::add_plugin): New function.
* options.h (Plugin_manager): Declare.
(General_options): Add --plugin option.
(General_options::has_plugins): New function.
(General_options::plugins): New function.
(General_options::add_plugin): New function.
(General_options::plugins_): New field.
* plugin.cc: New file.
* plugin.h: New file.
* readsyms.cc: Include "plugin.h".
(Read_symbols::do_read_symbols): Check for archive before checking
for ELF file. Call plugin hooks to claim files.
* resolve.cc (Symbol_table::resolve): Record when symbol is referenced
from a real object file; force override when processing replacement
files.
* symtab.cc (Symbol::init_fields): Initialize in_real_elf_ field.
(Symbol::init_base_object): Likewise.
(Symbol::init_base_output_data): Likewise.
(Symbol::init_base_output_segment): Likewise.
(Symbol::init_base_constant): Likewise.
(Symbol::init_base_undefined): Likewise.
(Symbol::output_section): Assert that object is not a plugin.
(Symbol_table::add_from_pluginobj): New function.
(Symbol_table::sized_finalize_symbol): Treat symbols from plugins as
undefined.
(Symbol_table::sized_write_globals): Likewise.
(Symbol_table::add_from_pluginobj): Instantiate template.
* symtab.h (Sized_pluginobj): Declare.
(Symbol::in_real_elf): New function.
(Symbol::set_in_real_elf): New function.
(Symbol::in_real_elf_): New field.
(Symbol_table::add_from_pluginobj): New function.
* testsuite/Makefile.am (AM_CFLAGS): New variable.
(LIBDL): New variable.
(LDADD): Add LIBDL.
(check_PROGRAMS): Add plugin_test_1 and plugin_test_2.
(check_SCRIPTS): Add plugin_test_1.sh and plugin_test_2.sh.
(check_DATA): Add plugin_test_1.err and plugin_test_2.err.
(MOSTLYCLEANFILES): Likewise.
* testsuite/Makefile.in: Regenerate.
* testsuite/plugin_test.c: New file.
* testsuite/plugin_test_1.sh: New file.
* testsuite/plugin_test_2.sh: New file.
(Layout::get_output_section): Ignore SHF_WRITE and SHF_EXECINSTR
in the name/type/flags to section mapping. Don't call
allocate_output_section.
(Layout::choose_output_section): Change parameter from adjust_name
to is_input_section. Don't permit input sections after sections
are attached to segments. Don't call allocate_output_section.
(Layout::layout_eh_frame): Call update_flags_for_input_section,
not write_enable_output_section.
(Layout::make_output_section): Don't push to
unattached_section_list_ nor call attach_to_segment. Call
attach_section_to_segment if sections are attached.
(Layout::attach_sections_to_segments): New function.
(Layout::attach_section_to_segment): New function.
(Layout::attach_allocated_section_to_segment): Rename from
attach_to_segment. Remove flags parameter.
(Layout::allocate_output_section): Remove function.
(Layout::write_enable_output_section): Remove function.
* layout.h (class Layout): Update for above changes. Add new
field sections_are_attached_.
* output.h (Output_section::update_flags_for_input_section): New
function.
* output.cc (Output_section::add_input_section): Call
update_flags_for_input_section.
* gold.cc (queue_middle_tasks): Call attach_sections_to_segments.
