but mark earlier ones as non-canonical
(offset_to_iterator): Update search target and example
(do_addr2line): Return extra lines in a vector*
(format_file_lineno): Extract from do_addr2line
(one_addr2line): Add vector* out-param
* dwarf_reader.h (Offset_to_lineno_entry): New field recording
when a lineno entry appeared last for its instruction
(Dwarf_line_info): Add vector* out-param
* object.cc (Relocate_info): Pass NULL for the vector* out-param
* symtab.cc (Odr_violation_compare): Include the lineno in the
comparison again.
(linenos_from_loc): New. Combine the canonical line for an
address with its other lines.
(True_if_intersect): New. Helper functor to make
std::set_intersection a query.
(detect_odr_violations): Compare sets of lines instead of just
one line for each function. This became less deterministic, but
has fewer false positives.
* symtab.h: Declarations.
* testsuite/Makefile.am (odr_violation2.o): Compile with -O2 to
mix an optimized and non-optimized object in the same binary
(odr_violation2.so): Same.
* testsuite/Makefile.in: Regenerate from Makefile.am.
* testsuite/debug_msg.cc (main): Make OdrDerived classes.
* testsuite/debug_msg.sh: Update line numbers and add
assertions.
* testsuite/odr_violation1.cc: Use OdrDerived, in a
non-optimized context.
* testsuite/odr_violation2.cc: Make sure Ordering::operator()
isn't inlined, and use OdrDerived in an optimized context.
* testsuite/odr_header1.h: Defines OdrDerived, where
optimization will change the
first-instruction-in-the-destructor's file and line number.
* testsuite/odr_header2.h: Defines OdrBase.
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++/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 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.
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