+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>
* testsuite/23_containers/vector_capacity.cc (test03): Move ...
const unsigned char*)): Fully qualify min() with std::.
* include/bits/stl_bvector.h (_M_insert_range(iterator,
_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,
forward_iterator_tag), _M_fill_insert(iterator, size_type, bool)):
Fully qualify distance() and max() with std::.
- * include/bits/stl_deque.h (_Deque_base::_M_initialize_map(size_t),
- _M_assign_aux(_ForwardIterator, _ForwardIterator, forward_iterator_tag)):
- Ditto.
- * include/bits/stl_list.h (size()): Fully qualify distance() with std::.
+ * include/bits/stl_deque.h
+ (_Deque_base::_M_initialize_map(size_t),
+ _M_assign_aux(_ForwardIterator, _ForwardIterator,
+ forward_iterator_tag)):
+ Ditto. * include/bits/stl_list.h (size()): Fully qualify
+ distance() with std::.
* include/bits/stl_tempbuf.h (_Temporary_buffer::_Temporary_buffer
(_ForwardIterator, _ForwardIterator)): Ditto.
* include/bits/stl_tree.h (_Rb_tree::erase(const _Key&),
--- /dev/null
+<?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>
projects / platform / upstream / linaro-gcc.git / commitdiff