* layout.h: #include <map>.
(class Kept_section): Change from struct to class. Add accessors
and setters. Add section size to Comdat_group mapping. Change
Comdat_group to std::map. Add is_comdat_ field. Add
linkonce_size field in union.
(class Layout): Update declaration of find_or_add_kept_section.
Don't declare find_kept_object.
* layout.cc (Layout::find_or_add_kept_section): Remove candidate
parameter. Add object, shndx, is_comdat, and is_group_name
parameters. Change all callers. Adjust for new Kept_section.
(Layout::find_kept_object): Remove.
* object.cc (Sized_relobj::include_section_group): Update use of
Kept_section. Rename secnum to shndx. Only record
Kept_comdat_section if sections are the same size.
(Sized_relobj::include_linkonce_section): Update use of
Kept_section. Only record Kept_comdat_section if sections are the
same size. Set size of linkonce section.
(Sized_relobj::map_to_kept_section): Update call to
get_kept_comdat_section.
* object.h (class Sized_relobj): Rename fields in
Kept_comdat_section to drop trailing underscores; change object
field to Relobj*. Change Kept_comdat_section_table to store
struct rather than pointer.
(Sized_relobj::set_kept_comdat_section): Remove kept parameter.
Add kept_object and kept_shndx parameters. Change all callers.
(Sized_relobj::get_kept_comdat_section): Change return type to
bool. Add kept_object and kept_shndx parameters. Change all
callers.
* plugin.cc (Pluginobj::include_comdat_group): Update call to
Layout::find_or_add_kept_section.
gold is an ELF linker. It is intended to have complete support for
ELF and to run as fast as possible on modern systems. For normal use
it is a drop-in replacement for the older GNU linker.
gold is part of the GNU binutils. See ../binutils/README for more
general notes, including where to send bug reports.
gold was originally developed at Google, and was contributed to the
Free Software Foundation in March 2008. At Google it was designed by
Ian Lance Taylor, with major contributions by Cary Coutant, Craig
Silverstein, and Andrew Chatham.
The existing GNU linker manual is intended to be accurate
documentation for features which gold supports. gold supports most of
the features of the GNU linker for ELF targets. Notable
omissions--features of the GNU linker not currently supported in
gold--are:
* MEMORY regions in linker scripts
* MRI compatible linker scripts
* cross-reference reports (--cref)
* position independent executables (-pie)
* various other minor options
Notes on the code
=================
These are some notes which may be helpful to people working on the
source code of gold itself.
gold is written in C++. It is a GNU program, and therefore follows
the GNU formatting standards as modified for C++. Source documents in
order of decreasing precedence:
http://www.gnu.org/prep/standards/
http://gcc.gnu.org/onlinedocs/libstdc++/17_intro/C++STYLE
http://www.zembu.com/eng/procs/c++style.html
The linker is intended to have complete support for cross-compilation,
while still supporting the normal case of native linking as fast as
possible. In order to do this, many classes are actually templates
whose parameter is the ELF file class (e.g., 32 bits or 64 bits). The
C++ code is the same, but we don't pay the execution time cost of
always using 64-bit integers if the target is 32 bits. Many of these
class templates also have an endianness parameter: true for
big-endian, false for little-endian.
The linker is multi-threaded. The Task class represents a single unit
of work. Task objects are stored on a single Workqueue object. Tasks
communicate via Task_token objects. Task_token objects are only
manipulated while holding the master Workqueue lock. Relatively few
mutexes are used.
Build requirements
==================
The gold source code uses templates heavily. Building it requires a
recent version of g++. g++ 4.0.3 is known to work. g++ 3.2 and g++
3.4.3 are known to fail.
The linker script parser uses features which are only in newer
versions of bison. bison 2.3 is known to work. bison 1.26 is known
to fail. If you are building gold from an official binutils release,
the bison output should already be included.
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