An unusually large number of stubs can result in the default section
group size being too large; sections plus stubs exceed the range of a
branch. Restarting the relaxation pass with a smaller group size can
sometimes help.
* powerpc.cc (struct Stub_table_owner): New.
(Powerpc_relobj): Rename stub_table_ to stub_table_index_, an
unsigned int vector. Update all references.
(powerpc_relobj::set_stub_table): Take an unsigned int param
rather than a Stub_table. Update callers.
(Powerpc_relobj::clear_stub_table): New function.
(Target_powerpc): Add relax_failed_, relax_fail_count_ and
stub_group_size_ vars.
(Target_powerpc::new_stub_table): Delete.
(max_branch_delta): New function, extracted from..
(Target_powerpc::Relocate::relocate): ..here..
(Target_powerpc::Branch_info::make_stub): ..and here. Return
status on whether stub created successfully.
(Stub_control::Stub_control): Add "no_size_errors" param. Move
default sizing to..
(Target_powerpc::do_relax): ..here. Init stub_group_size_ and
reduce on relax failure.
(Target_powerpc::group_sections): Add "no_size_errors" param.
Use stub_group_size_. Set up group info in a temp vector,
before building Stub_table vector. Account for input sections
possibly already converted to relaxed sections.
(Stub_table::init): Delete. Merge into..
(Stub_table::Stub_table): ..here.
(Stub_table::can_reach_stub): New function.
(Stub_table::add_plt_call_entry): Add "from" parameter and
return true iff stub could be reached.
(Stub_table::add_long_branch_entry): Similarly. Add "r_type"
param too.
(Stub_table::clear_stubs): Add "all" param.
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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:
* 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++/manual/source_code_style.html
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 and 4.1.3 are known to work. g++
3.2, 3.4.3, and 4.1.2 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.
Copyright (C) 2012-2014 Free Software Foundation, Inc.
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.
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