(class Initialize_lock): Rewrite as child of Once.
* gold-threads.cc (class Once_initialize): Define.
(once_pointer_control): New static variable.
(once_pointer, once_arg): New static variables.
(c_run_once): New static function.
(Once::Once, Once::run_once, Once::internal_run): New functions.
(class Initialize_lock_once): Remove.
(initialize_lock_control): Remove.
(initialize_lock_pointer): Remove.
(initialize_lock_once): Remove.
(Initialize_lock::Initialize_lock): Move to gold-threads.h.
(Initialize_lock::initialize): Rewrite.
(Initialize_lock::do_run_once): New function.
* archive.cc (Archive::interpret_header): Only clear name if it is
not already empty.
* fileread.cc: Include "gold-threads.h"
(file_counts_lock): New static variable.
(file_counts_initialize_lock): Likewise.
(File_read::release): Only increment counts when using --stats.
Use a lock around the increment.
* parameters.cc (class Set_parameters_target_once): Define.
(set_parameters_target_once): New static variable.
(Parameters::Parameters): Move here from parameters.h.
(Parameters::set_target): Rewrite.
(Parameters::set_target_once): New function.
(Parameters::clear_target): Move here and rewrite.
* parameters.h (class Parameters): Update declarations. Add
set_parameters_target_once_ field.
(Parameters::Parameters): Move to parameters.cc.
(Parameters::clear_target): Likewise.
* readsyms.cc (Read_symbols::do_group): Create a Start_group
task.
(Start_group::~Start_group): New function.
(Start_group::is_runnable): New function.
(Start_group::locks, Start_group::run): New functions.
(Finish_group::run): Change saw_undefined to size_t.
* readsyms.h (class Start_group): Define.
(class Finish_group): Change saw_undefined_ field to size_t.
(Finish_group::Finish_group): Remove saw_undefined and
this_blocker parameters. Change all callers.
(Finish_group::set_saw_undefined): New function.
(Finish_group::set_blocker): New function.
* symtab.h (class Symbol_table): Change saw_undefined to return
size_t. Change saw_undefined_ field to size_t.
* target-select.cc (Set_target_once::do_run_once): New function.
(Target_selector::Target_selector): Initialize set_target_once_
field. Don't initialize lock_ and initialize_lock_ fields.
(Target_selector::instantiate_target): Rewrite.
(Target_selector::set_target): New function.
* target-select.h (class Set_target_once): Define.
(class Target_selector): Update declarations. Make
Set_target_once a friend. Remove lock_ and initialize_lock_
fields. Add set_target_once_ field.
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)
* 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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