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+ *
+ * exesize.html
+ *
+ * HOWTO avoid production of excessively large executable files.
+ *
+ *
+ * $Id$
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+ * Written by Keith Marshall <keith@users.osdn.me>
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+ set_page("title", "MinGW Compiler Suite User Guide");
+ set_page("subtitle", "HOWTO Reduce the Size of MinGW Executable Files");
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+<div class="masthead" style="display: none">
+<p class="byline">Posted: 21-Oct-2008, by mingwadmin; Last Update: 22-Nov-2021</p>
+</div><!-- masthead -->
+<div class="overlapped" id="introduction">
+<h3>Introduction</h3>
+<p>There are a number of reasons why object files,
+executable files,
+and libraries may be larger than expected;
+principal among these are:
+</p>
+<ul>
+ <li>Overheads due to inclusion of debugging information;</li>
+ <li>C++ exception handling and run-time type information overheads;</li>
+ <li>C++ template class,
+ standard template library,
+ and standard C++ library overheads.
+ </li>
+</ul>
+<p>Below,
+we discuss techniques for reducing the impact of these overheads,
+and ultimately,
+a technique for compressing executable files,
+in order to minimize file size.
+</p>
+</div><!-- introduction -->
+
+<div class="overlapped" id="debug-info">
+<h3>Avoiding Inclusion of Debugging Information</h3>
+<p>Perhaps,
+the most common reason for executables being larger than expected,
+is that they include <em>debugging information</em> ;
+(this is added to the object modules,
+when source files are compiled with GCC’s
+“<code>-g</code>” option).
+Even when your own source files are compiled
+<em>without</em>  the “<code>-g</code>” option,
+libraries which are linked into your executable may have been compiled with it;
+(this may be the case,
+even for the system libraries which are distributed with MinGW).
+</p>
+<p>To exclude debugging information from your executable,
+simply use the “<code>strip</code>” command to remove it:
+</p>
+<pre class="box-out vt">
+C:\project> <kbd>strip example.exe</kbd>
+</pre>
+<p>Alternatively,
+use GCC’s “<code>-s</code>” option when linking:
+</p>
+<pre class="box-out vt">
+C:\project> <kbd>gcc -s example.o -o example.exe</kbd>
+</pre>
+</div><!-- debug-info -->
+
+<div class="overlapped" id="rtti">
+<h3>Reducing C++ Exception Handling and Run‑Time Type Information Overheads</h3>
+<p>By default,
+when compiling C++ code,
+GCC will compile in support for handling of C++ exceptions,
+and for interpretation of run‑time type information (RTTI).
+</p>
+<p>If your application does not use either of these,
+then you may choose to eliminate the overhead incurred by inclusion
+of the supporting infrastructure code,
+by compiling and linking with GCC’s
+“<code>-fno‑exceptions</code>”,
+and “<code>-fno‑rtti</code>” options,
+to eliminate the C++ exception handling,
+and RTTI interpretation overheads,
+respectively.
+</p>
+</div><!-- rtti -->
+
+<div class="overlapped" id="stl">
+<h3>Understanding the Effect of C++ Template Classes and the C++ Standard Library</h3>
+<p>When you use C++ template classes,
+either defined by yourself,
+or imported from the C++ Standard Template Library (STL),
+the compiler generates code separately for each instantiation
+(e.g. <code>vector<int></code> and <code>vector<string></code>),
+so the total code size can increase significantly.
+Other elements of the standard C++ library,
+such as <code>iostreams</code> classes,
+exception handling classes,
+and classes such as <code>std::string</code> introduce further overheads,
+which may seem large in comparison to the size of small applications,
+(such as “<code>Hello World</code>” type programs).
+</p>
+<p>In practice,
+these overheads are unavoidable;
+however,
+they are generally of constant size,
+and thus,
+will normally not be significant in comparison to the size
+of more realistic (typically larger) C++ application programs.
+</p>
+</div><!-- stl -->
+
+<div class="overlapped" id="upx">
+<h3>Using UPX to Compress Executable Files</h3>
+<p><a rel="noopener noreferrer" target="_blank"
+ href="https://upx.github.io/">UPX (the Ultimate Packer for eXecutables)
+</a>is a tool which,
+notwithstanding the avoidance of undesirable code generator overheads,
+as described above,
+compresses executable files to achieve further reduction of file size.
+It works for the executable file formats of several operating systems,
+including 32‑bit MS‑Windows,
+and is free for use with <em>all</em>  applications,
+(even those which are distributed commercially);
+it uses an efficient compression algorithm,
+producing compressed files which remain executable,
+and are rapidly decompressed <em>in‑place</em>, 
+when invoked.
+</p>
+<p>For most effective size reduction,
+UPX may deployed using <em>one</em>  of the following invocations,
+(acting on the original <em>uncompressed</em> 
+<code>example.exe</code>):
+</p>
+<pre class="box-out vt">
+C:\project> <kbd>upx --brute example.exe</kbd>
+C:\project> <kbd>upx --ultra-brute example.exe</kbd>
+C:\project> <kbd>upx --best example.exe</kbd>
+</pre>
+<p>to compress <code>example.exe</code> <em>in‑place</em>. 
+(Do note that,
+whereas the in‑place <em>decompression</em>  process
+can be performed quite rapidly,
+the <em>compression</em>  may require a considerably longer time;
+this is not generally a problem,
+since compression must be performed only once,
+for each newly generated executable file,
+whereas the relatively much quicker decompression must be repeated
+every time such a compressed executable file is run).
+</p>
+</div><!-- upx -->
+
+<!-- $RCSfile$: end of file -->
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