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diff --git a/gcc-4.8.1/libstdc++-v3/doc/html/manual/debug_mode_design.html b/gcc-4.8.1/libstdc++-v3/doc/html/manual/debug_mode_design.html deleted file mode 100644 index ccb8575e2..000000000 --- a/gcc-4.8.1/libstdc++-v3/doc/html/manual/debug_mode_design.html +++ /dev/null @@ -1,411 +0,0 @@ -<?xml version="1.0" encoding="UTF-8" standalone="no"?> -<!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"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Design</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.77.1" /><meta name="keywords" content="C++, library, debug" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="debug_mode.html" title="Chapter 17. Debug Mode" /><link rel="prev" href="debug_mode_using.html" title="Using" /><link rel="next" href="parallel_mode.html" title="Chapter 18. Parallel Mode" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Design</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="debug_mode_using.html">Prev</a> </td><th width="60%" align="center">Chapter 17. Debug Mode</th><td width="20%" align="right"> <a accesskey="n" href="parallel_mode.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.ext.debug_mode.design"></a>Design</h2></div></div></div><p> - </p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="debug_mode.design.goals"></a>Goals</h3></div></div></div><p> - </p><p> The libstdc++ debug mode replaces unsafe (but efficient) standard - containers and iterators with semantically equivalent safe standard - containers and iterators to aid in debugging user programs. The - following goals directed the design of the libstdc++ debug mode:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p><span class="emphasis"><em>Correctness</em></span>: the libstdc++ debug mode must not change - the semantics of the standard library for all cases specified in - the ANSI/ISO C++ standard. The essence of this constraint is that - any valid C++ program should behave in the same manner regardless - of whether it is compiled with debug mode or release mode. In - particular, entities that are defined in namespace std in release - mode should remain defined in namespace std in debug mode, so that - legal specializations of namespace std entities will remain - valid. A program that is not valid C++ (e.g., invokes undefined - behavior) is not required to behave similarly, although the debug - mode will abort with a diagnostic when it detects undefined - behavior.</p></li><li class="listitem"><p><span class="emphasis"><em>Performance</em></span>: the additional of the libstdc++ debug mode - must not affect the performance of the library when it is compiled - in release mode. Performance of the libstdc++ debug mode is - secondary (and, in fact, will be worse than the release - mode).</p></li><li class="listitem"><p><span class="emphasis"><em>Usability</em></span>: the libstdc++ debug mode should be easy to - use. It should be easily incorporated into the user's development - environment (e.g., by requiring only a single new compiler switch) - and should produce reasonable diagnostics when it detects a - problem with the user program. Usability also involves detection - of errors when using the debug mode incorrectly, e.g., by linking - a release-compiled object against a debug-compiled object if in - fact the resulting program will not run correctly.</p></li><li class="listitem"><p><span class="emphasis"><em>Minimize recompilation</em></span>: While it is expected that - users recompile at least part of their program to use debug - mode, the amount of recompilation affects the - detect-compile-debug turnaround time. This indirectly affects the - usefulness of the debug mode, because debugging some applications - may require rebuilding a large amount of code, which may not be - feasible when the suspect code may be very localized. There are - several levels of conformance to this requirement, each with its - own usability and implementation characteristics. In general, the - higher-numbered conformance levels are more usable (i.e., require - less recompilation) but are more complicated to implement than - the lower-numbered conformance levels. - </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Full recompilation</em></span>: The user must recompile his or - her entire application and all C++ libraries it depends on, - including the C++ standard library that ships with the - compiler. This must be done even if only a small part of the - program can use debugging features.</p></li><li class="listitem"><p><span class="emphasis"><em>Full user recompilation</em></span>: The user must recompile - his or her entire application and all C++ libraries it depends - on, but not the C++ standard library itself. This must be done - even if only a small part of the program can use debugging - features. This can be achieved given a full recompilation - system by compiling two versions of the standard library when - the compiler is installed and linking against the appropriate - one, e.g., a multilibs approach.</p></li><li class="listitem"><p><span class="emphasis"><em>Partial recompilation</em></span>: The user must recompile the - parts of his or her application and the C++ libraries it - depends on that will use the debugging facilities - directly. This means that any code that uses the debuggable - standard containers would need to be recompiled, but code - that does not use them (but may, for instance, use IOStreams) - would not have to be recompiled.</p></li><li class="listitem"><p><span class="emphasis"><em>Per-use recompilation</em></span>: The user must recompile the - parts of his or her application and the C++ libraries it - depends on where debugging should occur, and any other code - that interacts with those containers. This means that a set of - translation units that accesses a particular standard - container instance may either be compiled in release mode (no - checking) or debug mode (full checking), but must all be - compiled in the same way; a translation unit that does not see - that standard container instance need not be recompiled. This - also means that a translation unit <span class="emphasis"><em>A</em></span> that contains a - particular instantiation - (say, <code class="code">std::vector<int></code>) compiled in release - mode can be linked against a translation unit <span class="emphasis"><em>B</em></span> that - contains the same instantiation compiled in debug mode (a - feature not present with partial recompilation). While this - behavior is technically a violation of the One Definition - Rule, this ability tends to be very important in - practice. The libstdc++ debug mode supports this level of - recompilation. </p></li><li class="listitem"><p><span class="emphasis"><em>Per-unit recompilation</em></span>: The user must only - recompile the translation units where checking should occur, - regardless of where debuggable standard containers are - used. This has also been dubbed "<code class="code">-g</code> mode", - because the <code class="code">-g</code> compiler switch works in this way, - emitting debugging information at a per--translation-unit - granularity. We believe that this level of recompilation is in - fact not possible if we intend to supply safe iterators, leave - the program semantics unchanged, and not regress in - performance under release mode because we cannot associate - extra information with an iterator (to form a safe iterator) - without either reserving that space in release mode - (performance regression) or allocating extra memory associated - with each iterator with <code class="code">new</code> (changes the program - semantics).</p></li></ol></div><p> - </p></li></ul></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="debug_mode.design.methods"></a>Methods</h3></div></div></div><p> - </p><p>This section provides an overall view of the design of the - libstdc++ debug mode and details the relationship between design - decisions and the stated design goals.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="debug_mode.design.methods.wrappers"></a>The Wrapper Model</h4></div></div></div><p>The libstdc++ debug mode uses a wrapper model where the - debugging versions of library components (e.g., iterators and - containers) form a layer on top of the release versions of the - library components. The debugging components first verify that the - operation is correct (aborting with a diagnostic if an error is - found) and will then forward to the underlying release-mode - container that will perform the actual work. This design decision - ensures that we cannot regress release-mode performance (because the - release-mode containers are left untouched) and partially - enables <a class="link" href="debug_mode_design.html#methods.coexistence.link" title="Link- and run-time coexistence of release- and debug-mode components">mixing debug and - release code</a> at link time, although that will not be - discussed at this time.</p><p>Two types of wrappers are used in the implementation of the debug - mode: container wrappers and iterator wrappers. The two types of - wrappers interact to maintain relationships between iterators and - their associated containers, which are necessary to detect certain - types of standard library usage errors such as dereferencing - past-the-end iterators or inserting into a container using an - iterator from a different container.</p><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="debug_mode.design.methods.safe_iter"></a>Safe Iterators</h5></div></div></div><p>Iterator wrappers provide a debugging layer over any iterator that - is attached to a particular container, and will manage the - information detailing the iterator's state (singular, - dereferenceable, etc.) and tracking the container to which the - iterator is attached. Because iterators have a well-defined, common - interface the iterator wrapper is implemented with the iterator - adaptor class template <code class="code">__gnu_debug::_Safe_iterator</code>, - which takes two template parameters:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p><code class="code">Iterator</code>: The underlying iterator type, which must - be either the <code class="code">iterator</code> or <code class="code">const_iterator</code> - typedef from the sequence type this iterator can reference.</p></li><li class="listitem"><p><code class="code">Sequence</code>: The type of sequence that this iterator - references. This sequence must be a safe sequence (discussed below) - whose <code class="code">iterator</code> or <code class="code">const_iterator</code> typedef - is the type of the safe iterator.</p></li></ul></div></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="debug_mode.design.methods.safe_seq"></a>Safe Sequences (Containers)</h5></div></div></div><p>Container wrappers provide a debugging layer over a particular - container type. Because containers vary greatly in the member - functions they support and the semantics of those member functions - (especially in the area of iterator invalidation), container - wrappers are tailored to the container they reference, e.g., the - debugging version of <code class="code">std::list</code> duplicates the entire - interface of <code class="code">std::list</code>, adding additional semantic - checks and then forwarding operations to the - real <code class="code">std::list</code> (a public base class of the debugging - version) as appropriate. However, all safe containers inherit from - the class template <code class="code">__gnu_debug::_Safe_sequence</code>, - instantiated with the type of the safe container itself (an instance - of the curiously recurring template pattern).</p><p>The iterators of a container wrapper will be - <a class="link" href="debug_mode_design.html#debug_mode.design.methods.safe_iter" title="Safe Iterators">safe - iterators</a> that reference sequences of this type and wrap the - iterators provided by the release-mode base class. The debugging - container will use only the safe iterators within its own interface - (therefore requiring the user to use safe iterators, although this - does not change correct user code) and will communicate with the - release-mode base class with only the underlying, unsafe, - release-mode iterators that the base class exports.</p><p> The debugging version of <code class="code">std::list</code> will have the - following basic structure:</p><pre class="programlisting"> -template<typename _Tp, typename _Allocator = allocator<_Tp> - class debug-list : - public release-list<_Tp, _Allocator>, - public __gnu_debug::_Safe_sequence<debug-list<_Tp, _Allocator> > - { - typedef release-list<_Tp, _Allocator> _Base; - typedef debug-list<_Tp, _Allocator> _Self; - - public: - typedef __gnu_debug::_Safe_iterator<typename _Base::iterator, _Self> iterator; - typedef __gnu_debug::_Safe_iterator<typename _Base::const_iterator, _Self> const_iterator; - - // duplicate std::list interface with debugging semantics - }; -</pre></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="debug_mode.design.methods.precond"></a>Precondition Checking</h4></div></div></div><p>The debug mode operates primarily by checking the preconditions of - all standard library operations that it supports. Preconditions that - are always checked (regardless of whether or not we are in debug - mode) are checked via the <code class="code">__check_xxx</code> macros defined - and documented in the source - file <code class="code">include/debug/debug.h</code>. Preconditions that may or - may not be checked, depending on the debug-mode - macro <code class="code">_GLIBCXX_DEBUG</code>, are checked via - the <code class="code">__requires_xxx</code> macros defined and documented in the - same source file. Preconditions are validated using any additional - information available at run-time, e.g., the containers that are - associated with a particular iterator, the position of the iterator - within those containers, the distance between two iterators that may - form a valid range, etc. In the absence of suitable information, - e.g., an input iterator that is not a safe iterator, these - precondition checks will silently succeed.</p><p>The majority of precondition checks use the aforementioned macros, - which have the secondary benefit of having prewritten debug - messages that use information about the current status of the - objects involved (e.g., whether an iterator is singular or what - sequence it is attached to) along with some static information - (e.g., the names of the function parameters corresponding to the - objects involved). When not using these macros, the debug mode uses - either the debug-mode assertion - macro <code class="code">_GLIBCXX_DEBUG_ASSERT</code> , its pedantic - cousin <code class="code">_GLIBCXX_DEBUG_PEDASSERT</code>, or the assertion - check macro that supports more advance formulation of error - messages, <code class="code">_GLIBCXX_DEBUG_VERIFY</code>. These macros are - documented more thoroughly in the debug mode source code.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="debug_mode.design.methods.coexistence"></a>Release- and debug-mode coexistence</h4></div></div></div><p>The libstdc++ debug mode is the first debug mode we know of that - is able to provide the "Per-use recompilation" (4) guarantee, that - allows release-compiled and debug-compiled code to be linked and - executed together without causing unpredictable behavior. This - guarantee minimizes the recompilation that users are required to - perform, shortening the detect-compile-debug bug hunting cycle - and making the debug mode easier to incorporate into development - environments by minimizing dependencies.</p><p>Achieving link- and run-time coexistence is not a trivial - implementation task. To achieve this goal we required a small - extension to the GNU C++ compiler (since incorporated into the C++11 language specification, described in the GCC Manual for the C++ language as - <a class="link" href="http://gcc.gnu.org/onlinedocs/gcc/Namespace-Association.html#Namespace-Association" target="_top">namespace - association</a>), and a complex organization of debug- and - release-modes. The end result is that we have achieved per-use - recompilation but have had to give up some checking of the - <code class="code">std::basic_string</code> class template (namely, safe - iterators). -</p><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="methods.coexistence.compile"></a>Compile-time coexistence of release- and debug-mode components</h5></div></div></div><p>Both the release-mode components and the debug-mode - components need to exist within a single translation unit so that - the debug versions can wrap the release versions. However, only one - of these components should be user-visible at any particular - time with the standard name, e.g., <code class="code">std::list</code>. </p><p>In release mode, we define only the release-mode version of the - component with its standard name and do not include the debugging - component at all. The release mode version is defined within the - namespace <code class="code">std</code>. Minus the namespace associations, this - method leaves the behavior of release mode completely unchanged from - its behavior prior to the introduction of the libstdc++ debug - mode. Here's an example of what this ends up looking like, in - C++.</p><pre class="programlisting"> -namespace std -{ - template<typename _Tp, typename _Alloc = allocator<_Tp> > - class list - { - // ... - }; -} // namespace std -</pre><p>In debug mode we include the release-mode container (which is now -defined in the namespace <code class="code">__cxx1998</code>) and also the -debug-mode container. The debug-mode container is defined within the -namespace <code class="code">__debug</code>, which is associated with namespace -<code class="code">std</code> via the C++11 namespace association language feature. This -method allows the debug and release versions of the same component to -coexist at compile-time and link-time without causing an unreasonable -maintenance burden, while minimizing confusion. Again, this boils down -to C++ code as follows:</p><pre class="programlisting"> -namespace std -{ - namespace __cxx1998 - { - template<typename _Tp, typename _Alloc = allocator<_Tp> > - class list - { - // ... - }; - } // namespace __gnu_norm - - namespace __debug - { - template<typename _Tp, typename _Alloc = allocator<_Tp> > - class list - : public __cxx1998::list<_Tp, _Alloc>, - public __gnu_debug::_Safe_sequence<list<_Tp, _Alloc> > - { - // ... - }; - } // namespace __cxx1998 - - // namespace __debug __attribute__ ((strong)); - inline namespace __debug { } -} -</pre></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="methods.coexistence.link"></a>Link- and run-time coexistence of release- and - debug-mode components</h5></div></div></div><p>Because each component has a distinct and separate release and -debug implementation, there is no issue with link-time -coexistence: the separate namespaces result in different mangled -names, and thus unique linkage.</p><p>However, components that are defined and used within the C++ -standard library itself face additional constraints. For instance, -some of the member functions of <code class="code"> std::moneypunct</code> return -<code class="code">std::basic_string</code>. Normally, this is not a problem, but -with a mixed mode standard library that could be using either -debug-mode or release-mode <code class="code"> basic_string</code> objects, things -get more complicated. As the return value of a function is not -encoded into the mangled name, there is no way to specify a -release-mode or a debug-mode string. In practice, this results in -runtime errors. A simplified example of this problem is as follows. -</p><p> Take this translation unit, compiled in debug-mode: </p><pre class="programlisting"> -// -D_GLIBCXX_DEBUG -#include <string> - -std::string test02(); - -std::string test01() -{ - return test02(); -} - -int main() -{ - test01(); - return 0; -} -</pre><p> ... and linked to this translation unit, compiled in release mode:</p><pre class="programlisting"> -#include <string> - -std::string -test02() -{ - return std::string("toast"); -} -</pre><p> For this reason we cannot easily provide safe iterators for - the <code class="code">std::basic_string</code> class template, as it is present - throughout the C++ standard library. For instance, locale facets - define typedefs that include <code class="code">basic_string</code>: in a mixed - debug/release program, should that typedef be based on the - debug-mode <code class="code">basic_string</code> or the - release-mode <code class="code">basic_string</code>? While the answer could be - "both", and the difference hidden via renaming a la the - debug/release containers, we must note two things about locale - facets:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>They exist as shared state: one can create a facet in one - translation unit and access the facet via the same type name in a - different translation unit. This means that we cannot have two - different versions of locale facets, because the types would not be - the same across debug/release-mode translation unit barriers.</p></li><li class="listitem"><p>They have virtual functions returning strings: these functions - mangle in the same way regardless of the mangling of their return - types (see above), and their precise signatures can be relied upon - by users because they may be overridden in derived classes.</p></li></ol></div><p>With the design of libstdc++ debug mode, we cannot effectively hide - the differences between debug and release-mode strings from the - user. Failure to hide the differences may result in unpredictable - behavior, and for this reason we have opted to only - perform <code class="code">basic_string</code> changes that do not require ABI - changes. The effect on users is expected to be minimal, as there are - simple alternatives (e.g., <code class="code">__gnu_debug::basic_string</code>), - and the usability benefit we gain from the ability to mix debug- and - release-compiled translation units is enormous.</p></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="methods.coexistence.alt"></a>Alternatives for Coexistence</h5></div></div></div><p>The coexistence scheme above was chosen over many alternatives, - including language-only solutions and solutions that also required - extensions to the C++ front end. The following is a partial list of - solutions, with justifications for our rejection of each.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p><span class="emphasis"><em>Completely separate debug/release libraries</em></span>: This is by - far the simplest implementation option, where we do not allow any - coexistence of debug- and release-compiled translation units in a - program. This solution has an extreme negative affect on usability, - because it is quite likely that some libraries an application - depends on cannot be recompiled easily. This would not meet - our <span class="emphasis"><em>usability</em></span> or <span class="emphasis"><em>minimize recompilation</em></span> criteria - well.</p></li><li class="listitem"><p><span class="emphasis"><em>Add a <code class="code">Debug</code> boolean template parameter</em></span>: - Partial specialization could be used to select the debug - implementation when <code class="code">Debug == true</code>, and the state - of <code class="code">_GLIBCXX_DEBUG</code> could decide whether the - default <code class="code">Debug</code> argument is <code class="code">true</code> - or <code class="code">false</code>. This option would break conformance with the - C++ standard in both debug <span class="emphasis"><em>and</em></span> release modes. This would - not meet our <span class="emphasis"><em>correctness</em></span> criteria. </p></li><li class="listitem"><p><span class="emphasis"><em>Packaging a debug flag in the allocators</em></span>: We could - reuse the <code class="code">Allocator</code> template parameter of containers - by adding a sentinel wrapper <code class="code">debug<></code> that - signals the user's intention to use debugging, and pick up - the <code class="code">debug<></code> allocator wrapper in a partial - specialization. However, this has two drawbacks: first, there is a - conformance issue because the default allocator would not be the - standard-specified <code class="code">std::allocator<T></code>. Secondly - (and more importantly), users that specify allocators instead of - implicitly using the default allocator would not get debugging - containers. Thus this solution fails the <span class="emphasis"><em>correctness</em></span> - criteria.</p></li><li class="listitem"><p><span class="emphasis"><em>Define debug containers in another namespace, and employ - a <code class="code">using</code> declaration (or directive)</em></span>: This is an - enticing option, because it would eliminate the need for - the <code class="code">link_name</code> extension by aliasing the - templates. However, there is no true template aliasing mechanism - in C++, because both <code class="code">using</code> directives and using - declarations disallow specialization. This method fails - the <span class="emphasis"><em>correctness</em></span> criteria.</p></li><li class="listitem"><p><span class="emphasis"><em> Use implementation-specific properties of anonymous - namespaces. </em></span> - See <a class="link" href="http://gcc.gnu.org/ml/libstdc++/2003-08/msg00004.html" target="_top"> this post - </a> - This method fails the <span class="emphasis"><em>correctness</em></span> criteria.</p></li><li class="listitem"><p><span class="emphasis"><em>Extension: allow reopening on namespaces</em></span>: This would - allow the debug mode to effectively alias the - namespace <code class="code">std</code> to an internal namespace, such - as <code class="code">__gnu_std_debug</code>, so that it is completely - separate from the release-mode <code class="code">std</code> namespace. While - this will solve some renaming problems and ensure that - debug- and release-compiled code cannot be mixed unsafely, it ensures that - debug- and release-compiled code cannot be mixed at all. For - instance, the program would have two <code class="code">std::cout</code> - objects! This solution would fails the <span class="emphasis"><em>minimize - recompilation</em></span> requirement, because we would only be able to - support option (1) or (2).</p></li><li class="listitem"><p><span class="emphasis"><em>Extension: use link name</em></span>: This option involves - complicated re-naming between debug-mode and release-mode - components at compile time, and then a g++ extension called <span class="emphasis"><em> - link name </em></span> to recover the original names at link time. There - are two drawbacks to this approach. One, it's very verbose, - relying on macro renaming at compile time and several levels of - include ordering. Two, ODR issues remained with container member - functions taking no arguments in mixed-mode settings resulting in - equivalent link names, <code class="code"> vector::push_back() </code> being - one example. - See <a class="link" href="http://gcc.gnu.org/ml/libstdc++/2003-08/msg00177.html" target="_top">link - name</a> </p></li></ul></div><p>Other options may exist for implementing the debug mode, many of - which have probably been considered and others that may still be - lurking. This list may be expanded over time to include other - options that we could have implemented, but in all cases the full - ramifications of the approach (as measured against the design goals - for a libstdc++ debug mode) should be considered first. The DejaGNU - testsuite includes some testcases that check for known problems with - some solutions (e.g., the <code class="code">using</code> declaration solution - that breaks user specialization), and additional testcases will be - added as we are able to identify other typical problem cases. These - test cases will serve as a benchmark by which we can compare debug - mode implementations.</p></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="debug_mode.design.other"></a>Other Implementations</h3></div></div></div><p> - </p><p> There are several existing implementations of debug modes for C++ - standard library implementations, although none of them directly - supports debugging for programs using libstdc++. The existing - implementations include:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p><a class="link" href="http://www.mathcs.sjsu.edu/faculty/horstman/safestl.html" target="_top">SafeSTL</a>: - SafeSTL was the original debugging version of the Standard Template - Library (STL), implemented by Cay S. Horstmann on top of the - Hewlett-Packard STL. Though it inspired much work in this area, it - has not been kept up-to-date for use with modern compilers or C++ - standard library implementations.</p></li><li class="listitem"><p><a class="link" href="http://www.stlport.org/" target="_top">STLport</a>: STLport is a free - implementation of the C++ standard library derived from the <a class="link" href="http://www.sgi.com/tech/stl/" target="_top">SGI implementation</a>, and - ported to many other platforms. It includes a debug mode that uses a - wrapper model (that in some ways inspired the libstdc++ debug mode - design), although at the time of this writing the debug mode is - somewhat incomplete and meets only the "Full user recompilation" (2) - recompilation guarantee by requiring the user to link against a - different library in debug mode vs. release mode.</p></li><li class="listitem"><p>Metrowerks CodeWarrior: The C++ standard library - that ships with Metrowerks CodeWarrior includes a debug mode. It is - a full debug-mode implementation (including debugging for - CodeWarrior extensions) and is easy to use, although it meets only - the "Full recompilation" (1) recompilation - guarantee.</p></li></ul></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="debug_mode_using.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="debug_mode.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="parallel_mode.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Using </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 18. Parallel Mode</td></tr></table></div></body></html>
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