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documentation.html: Add link for debug.html.

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2002-12-18  Benjamin Kosnik  <bkoz@redhat.com>

 	* docs/html/documentation.html: Add link for debug.html.
	* docs/html/debug.html: New.

From-SVN: r60302
This commit is contained in:
Benjamin Kosnik 2002-12-19 08:18:14 +00:00
parent c034372c80
commit b5ff3a9077
3 changed files with 242 additions and 5 deletions
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18
libstdc++-v3/ChangeLog
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@ -1,3 +1,8 @@
2002-12-18 Benjamin Kosnik <bkoz@redhat.com>
* docs/html/documentation.html: Add link for debug.html.
* docs/html/debug.html: New.
2002-12-18 Kaveh R. Ghazi <ghazi@caip.rutgers.edu> 2002-12-18 Kaveh R. Ghazi <ghazi@caip.rutgers.edu>
* testsuite/23_containers/vector_capacity.cc (test03): Move ... * testsuite/23_containers/vector_capacity.cc (test03): Move ...
@ -189,14 +194,17 @@
const unsigned char*)): Fully qualify min() with std::. const unsigned char*)): Fully qualify min() with std::.
* include/bits/stl_bvector.h (_M_insert_range(iterator, * include/bits/stl_bvector.h (_M_insert_range(iterator,
_ForwardIterator, _ForwardIterator, forward_iterator_tag), _ForwardIterator, _ForwardIterator, forward_iterator_tag),
_M_assign_aux(_ForwardIterator, _ForwardIterator, forward_iterator_tag), _M_assign_aux(_ForwardIterator, _ForwardIterator,
forward_iterator_tag),
_M_initialize_range(_ForwardIterator, _ForwardIterator, _M_initialize_range(_ForwardIterator, _ForwardIterator,
forward_iterator_tag), _M_fill_insert(iterator, size_type, bool)): forward_iterator_tag), _M_fill_insert(iterator, size_type, bool)):
Fully qualify distance() and max() with std::. Fully qualify distance() and max() with std::.
* include/bits/stl_deque.h (_Deque_base::_M_initialize_map(size_t), * include/bits/stl_deque.h
_M_assign_aux(_ForwardIterator, _ForwardIterator, forward_iterator_tag)): (_Deque_base::_M_initialize_map(size_t),
Ditto. _M_assign_aux(_ForwardIterator, _ForwardIterator,
* include/bits/stl_list.h (size()): Fully qualify distance() with std::. forward_iterator_tag)):
Ditto. * include/bits/stl_list.h (size()): Fully qualify
distance() with std::.
* include/bits/stl_tempbuf.h (_Temporary_buffer::_Temporary_buffer * include/bits/stl_tempbuf.h (_Temporary_buffer::_Temporary_buffer
(_ForwardIterator, _ForwardIterator)): Ditto. (_ForwardIterator, _ForwardIterator)): Ditto.
* include/bits/stl_tree.h (_Rb_tree::erase(const _Key&), * include/bits/stl_tree.h (_Rb_tree::erase(const _Key&),

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libstdc++-v3/docs/html/debug.html Normal file
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<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta name="AUTHOR" content="bkoz@gcc.gnu.org (Benjamin Kosnik)" />
<meta name="KEYWORDS" content="c++, libstdc++, gdb, g++, debug" />
<meta name="DESCRIPTION" content="Debugging C++ binaries" />
<meta name="GENERATOR" content="vi and ten fingers" />
<title>Debugging schemes and strategies</title>
<link rel="StyleSheet" href="lib3styles.css" />
</head>
<body>
<h1 class="centered"><a name="top">Debugging schemes and strategies</a></h1>
<p class="fineprint"><em>
<p>The latest version of this document is always available at
<a href="http://gcc.gnu.org/onlinedocs/libstdc++/debug.html">
http://gcc.gnu.org/onlinedocs/libstdc++/debug.html</a>.
</p>
<p>To the <a href="http://gcc.gnu.org/libstdc++/">libstdc++-v3 homepage</a>.
</p>
</em></p>
<!-- ####################################################### -->
<hr />
<p>
There are numerous things that can be done to improve the ease with
which C++ binaries are debugged when using the GNU C++
tool chain. Here are some things to keep in mind when debugging C++
code with GNU tools.
</p>
<h3 class="left"><a name="g++">Compiler flags determine debug info</a></h3>
<p>
The default optimizations and debug flags for a libstdc++ build are
<code>-g -O2</code>. However, both debug and optimization flags can
be varied to change debugging characteristics. For instance,
turning off all optimization via the <code>-g -O0</code> flag will
disable inlining, so that stepping through all functions, including
inlined constructors and destructors, is possible. Or, the debug
format that the compiler and debugger use to communicate
information about source constructs can be changed via <code>
-gdwarf-2 </code> or <code> -gstabs </code> flags: some debugging
formats permit more expressive type and scope information to be
shown in gdb.
The default debug information for a particular platform can be
identified via the value set by the PREFERRED_DEBUGGING_TYPE macro
in the gcc sources.
</p>
<p>
Many other options are available: please see
<a href=http://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html#Debugging%20Options> "Options for Debugging Your Program" </a>
in Using the GNU Compiler Collection (GCC) for a complete list.
</p>
<h3 class="left"><a name="lib">Using special flags to make a debug binary</a></h3>
<p>
There are two ways to build libstdc++ with debug flags. The first
is to run make from the toplevel in a freshly-configured tree with
specialized debug <code>CXXFLAGS</code>, as in <dd> <code> make
CXXFLAGS='-g3 -O0' all </code></dd>
</p>
<p>
This quick and dirty approach is often sufficient for quick
debugging tasks, but the lack of state can be confusing in the long
term.
</p>
<p>
A second approach is to use the configuration flags
</p>
<dd><code>--enable-debug </code></dd>
<p>
and perhaps
</p>
<dd><code>--enable-debug-flags </code></dd>
<p>
to create a separate debug build. Both the normal build and the
debug build will persist, without having to specify
<code>CXXFLAGS</code>, and the debug library will be installed in a
separate directory tree, in <code>(prefix)/lib/debug</code>. For
more information, look at the configuration options document
<a href=http://gcc.gnu.org/onlinedocs/libstdc++/configopts.html> here</a>
</p>
<h3 class="left"><a name="mem">Tips for memory leak hunting</a></h3>
<p>
There are various third party memory tracing and debug utilities
that can be used to provide detailed memory allocation information
about C++ code. An exhaustive list of tools is not going to be
attempted, but include <code>mtrace</code>, <code>valgrind</code>,
<code>mudflap</code>, and <code>purify</code>. Also highly
recommended are <code>libcwd</code> and some other one that I
forget right now.
</p>
<p>
Regardless of the memory debugging tool being used, there is one
thing of great importance to keep in mind when debugging C++ code
that uses <code>new</code> and <code>delete</code>:
there are different kinds of allocation schemes that can be used by
<code> std::allocator </code>. For implementation details, see this
<a href=http://gcc.gnu.org/onlinedocs/libstdc++/ext/howto.html#3>
document </a> and look specifically for <code>GLIBCPP_FORCE_NEW</code>.
</p>
<p>
In a nutshell, the default allocator used by <code>
std::allocator</code> is a high-performance pool allocator, and can
give the mistaken impression that memory is being leaked, when in
reality the memory is reclaimed after program termination.
</p>
<p> For valgrind, there are some specific items to keep in mind. First
of all, use a version of valgrind that will work with current GNU
C++ tools: the first that can do this is valgrind 1.0.4, but later
versions should work at least as well. Second of all, use a
completely unoptimized build to avoid confusing valgrind. Third,
use GLIBCPP_FORCE_NEW to keep extraneous pool allocation noise from
cluttering debug information.
</p>
<p>
Fourth, it may be necessary to force deallocation in other
libraries as well, namely the "C" library. On linux, this can be
accomplished with the appropriate use of the
<code>__cxa_atexit</code> or <code>atexit</code> functions.
</p>
<pre>
#include <cstdlib>
extern "C" void __libc_freeres(void);
void do_something() { }
int main()
{
atexit(__libc_freeres);
do_test();
return 0;
}
</pre>
<p>
or, using <code>__cxa_atexit</code>:
</p>
<pre>
extern "C" void __libc_freeres(void);
extern "C" int __cxa_atexit(void (*func) (void *), void *arg, void *d);
void do_something() { }
int main()
{
extern void* __dso_handle __attribute__ ((__weak__));
__cxa_atexit((void (*) (void *)) __libc_freeres, NULL,
&__dso_handle ? __dso_handle : NULL);
do_test();
return 0;
}
</pre>
<p>
Suggested valgrind flags, given the suggestions above about setting
up the runtime environment, library, and test file, might be:
<dd><code>valgrind -v --num-callers=20 --leak-check=yes
--leak-resolution=high --show-reachable=yes a.out</code></dd>
</p>
<h3 class="left"><a name="gdb">Some gdb strategies</a></h3>
<p>
Many options are available for gdb itself: please see <a
href=http://sources.redhat.com/gdb/current/onlinedocs/gdb_13.html#SEC109>
"GDB features for C++" </a> in the gdb documentation. Also
recommended: the other parts of this manual.
</p>
<p>
These settings can either be switched on in at the gdb command
line, or put into a .gdbint file to establish default debugging
characteristics, like so:
</p>
<pre>
set print pretty on
set print object on
set print static-members on
set print vtbl on
set print demangle on
set demangle-style gnu-v3
</pre>
<p>Return <a href="#top">to the top of the page</a> or
<a href="http://gcc.gnu.org/libstdc++/">to the libstdc++ homepage</a>.
</p>
<!-- ####################################################### -->
<hr />
<p class="fineprint"><em>
See <a href="17_intro/license.html">license.html</a> for copying conditions.
Comments and suggestions are welcome, and may be sent to
<a href="mailto:libstdc++@gcc.gnu.org">the libstdc++ mailing list</a>.
</em></p>
</body>
</html>

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libstdc++-v3/docs/html/documentation.html
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<ul> <ul>
<li><a href="configopts.html">Configure options</a></li> <li><a href="configopts.html">Configure options</a></li>
<li><a href="install.html">Getting started: configure, build, install</a> <li><a href="install.html">Getting started: configure, build, install</a>
<li><a href="debug.html">Debugging schemes and strategies</a>
</li> </li>
</ul> </ul>