* object.h (class Relobj): Change map_to_output_ to
output_sections_, and just keep a section pointer. Change all
uses. Move comdat group support to Sized_relobj.
(Relobj::is_section_specially_mapped): Remove.
(Relobj::output_section): Remove poff parameter. Change all
callers.
(Relobj::output_section_offset): New function.
(Relobj::set_section_offset): Rewrite.
(Relobj::map_to_output): Remove.
(Relobj::output_sections): New function.
(Relobj::do_output_section_offset): New pure virtual function.
(Relobj::do_set_section_offset): Likewise.
(class Sized_relobj): Add section_offsets_ field. Add comdat
group support from Relobj. Update declarations.
(Sized_relobj::get_output_section_offset): New function.
(Sized_relobj::do_output_section_offset): New function.
(Sized_relobj::do_set_section_offset): New function.
* object.cc (Relobj::output_section_address): Remove.
(Sized_relobj::Sized_relobj): Initialize new fields.
(Sized_relobj::include_section_group): Cast find_kept_object to
Sized_relobj.
(Sized_relobj::include_linkonce_section): Likewise.
(Sized_relobj::do_layout): Use separate arrays for output section
and output offset.
(Sized_relobj::do_count_local_symbols): Change map_to_output to
output_sections.
(Sized_relobj::do_finalize_local_symbols): Change map_to_output to
output_sections and section_offsets.
(Sized_relobj::write_local_symbols): Likewise.
(map_to_kept_section): Compute output address directly.
* reloc.cc (Sized_relobj::do_read_relocs): Change map_to_output to
output_sections and section_offsets.
(Sized_relobj::write_sections): Likewise.
(Sized_relobj::relocate_sections): Likewise.
* symtab.cc (sized_finalize_symbol): Use output_section_offset.
* output.h (class Output_reloc): Update declarations. Change
u2_.relobj to Sized_relobj*.
(class Output_data_reloc): Change add functions to use
Sized_relobj*.
* output.cc (Output_reloc::Output_reloc): Change relobj to
Sized_relobj*.
(Output_reloc::local_section_offset): Change return type to
Elf_Addr. Use get_output_section_offset.
(Output_reloc::get_address): Likewise.
(Output_section::is_input_address_mapped): Don't call
is_section_specially_mapped.
(Output_section::output_offset): Likewise.
(Output_section::output_address): Likewise.
(Output_section::starting_output_address): Likewise.
* copy-relocs.cc (Copy_relocs::copy_reloc): Change object
parameter to Sized_relobj*.
(Copy_relocs::need_copy_reloc): Likewise.
(Copy_relocs::save): Likewise.
* copy-relocs.h (class Copy_relocs): Update declarations.
(class Copy_relocs::Copy_reloc_entry): Change constructor to use
Sized_relobj*. Change relobj_ field to Sized_relobj*.
* target-reloc.h (relocate_for_relocatable): Change
offset_in_output_section type to Elf_Addr. Change code that uses
it as well.
* layout.cc (Layout::layout): Always set *off.
* mapfile.cc (Mapfile::print_input_section): Use
output_section_offset.
* i386.cc (Target_i386::copy_reloc): Change object parameter to
Sized_relobj*.
* powerpc.cc (Target_powerpc::copy_reloc): Likewise.
* sparc.cc (Target_sparc::copy_reloc): Likewise.
* x86_64.cc (Target_x86_64::copy_reloc): Likewise.
info section.
(Layout::add_comdat): Add new parameters. Change type
of signature parameter. Add object and shndx to signatures table.
(Layout::find_kept_object): New function.
* layout.h: Include <cstring>.
(Layout::is_debug_info_section): New function.
(Layout::add_comdat): Add new parameters.
(Layout::find_kept_object): New function.
(Layout::Kept_section): New struct.
(Layout::Signatures): Change type of map range.
* object.cc (Relobj::output_section_address): New function.
(Sized_relobj::include_section_group): Add new parameters. Change
calls to Layout::add_comdat. Change to build table of kept comdat
groups and table mapping discarded sections to kept sections.
(Sized_relobj::include_linkonce_section): Likewise. Add new parameter.
(Sized_relobj::do_layout): Change calls to include_section_group and
include_linkonce_section.
(Sized_relobj::do_finalize_local_symbols): Do not set local symbol
value to zero when section is discarded.
(Sized_relobj::map_to_kept_section): New function.
* object.h (Relobj::output_section_address): New function.
(Relobj::Comdat_group): New type.
(Relobj::find_comdat_group): New function.
(Relobj::Comdat_group_table): New type.
(Relobj::Kept_comdat_section): New type.
(Relobj::Kept_comdat_section_table): New type.
(Relobj::add_comdat_group): New function.
(Relobj::set_kept_comdat_section): New function.
(Relobj::get_kept_comdat_section): New function.
(Relobj::comdat_groups_): New field.
(Relobj::kept_comdat_sections_): New field.
(Symbol_value::input_value): Update comment.
(Sized_relobj::map_to_kept_section) New function.
(Sized_relobj::include_linkonce_section): Add new parameter.
* target-reloc.h (Comdat_behavior): New type.
(get_comdat_behavior): New function.
(relocate_section): Add code to map a discarded section to the
corresponding kept section when applying a relocation.
