better-enums/Performance.html
2020-10-19 09:11:42 +03:00

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<title>Performance - Better Enums</title>
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<h1><a href="index.html">Better Enums</a></h1>
<h2>Reflective compile-time enums for <span class="cpp">C++</span></h2>
<h3>Open-source under the BSD license</h3>
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<p>Version 0.11.3</p>
<p>To install, just add <code>enum.h</code> to your project.</p>
<p>
Visit the GitHub repo for issues, feedback, and the latest development.
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<h2>Performance</h2>
<p>A basic performance test is run on
<a href="CompilerSupport.html#TestedConfigurations">every compiler tested</a>. It
doesn't try to be very accurate &mdash; it just stress-tests the compiler once
to get a rough idea of how long it takes to compile Better Enums.</p>
<p>The files compared in the test are as follows:</p>
<ul>
<li><a href="https://github.com/aantron/better-enums/blob/0.11.3/test/performance/4-declare_enums.cc">One file</a> includes
<code>enum.h</code> and declares 647 constants across 36 Better Enums.</li>
<li>The <a href="https://github.com/aantron/better-enums/blob/0.11.3/test/performance/5-iostream.cc">other file</a> <em>only</em>
includes <code>iostream</code> and does nothing with it.</li>
</ul>
<p>The argument is that if compiling a bunch of Better Enums is faster, or about as
fast as, including a single standard header such as <code>iostream</code>, then Better
Enums is fast enough for general use.</p>
<p>Results are given for select compilers and
<a href="CompilerSupport.html#CompileTimeReflectionConfigurations">configurations</a>
as ratios of how long it took to compile the Better Enums file to how long it
took to compile the <code>iostream</code> file. The less the ratio, the better. Ratios less
than 1 mean the enums compiled faster, and ratios greater than 1 mean <code>iostream</code>
compiled faster.</p>
<ul>
<li>clang 3.6, fast <code>constexpr</code>: 0.66</li>
<li>clang 3.6, full <code>constexpr</code>: 2.25</li>
<li>gcc 5.1, fast <code>constexpr</code>: 1.58</li>
<li>gcc 5.1, full <code>constexpr</code>: 4.23</li>
<li>VC2015RC, <span class="cpp">C++</span><span class="eleven">98</span>: 1.18</li>
</ul>
<p>The time to merely include <code>enum.h</code> vary widely by compiler, with clang being
by far the fastest. The ratios to <code>iostream</code> are given below.</p>
<ul>
<li>clang 3.6: 0.15</li>
<li>gcc 5.1: 0.77</li>
<li>VC2015RC: 0.82</li>
</ul>
<p>On my test machines, clang processed the file in 40ms, gcc took 230ms, and
VC2015 took 820ms. The first two are comparable to each other, but VC2015 runs
on a different machine.</p>
<hr>
<p>In general, I am very sensitive to performance. Better Enums was originally
developed in the context of a commercial project where slow running times <em>and</em>
slow compilation times were unacceptable. I am continuing to develop it in this
spirit.</p>
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Copyright &copy; 2015-2019 Anton Bachin. Released under the BSD 2-clause
license. See
<a href="https://github.com/aantron/better-enums/blob/0.11.3/doc/LICENSE">
LICENSE</a>.
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This page is part of the documentation for Better Enums 0.11.3.
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