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  • Committer: Bazaar Package Importer
  • Author(s): Alexandre Fayolle
  • Date: 2007-04-13 09:33:09 UTC
  • Revision ID: james.westby@ubuntu.com-20070413093309-yoojh4jcoocu2krz
Tags: upstream-1.0.0
Import upstream version 1.0.0

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pypy/doc/config/translation.backendopt.mallocs.html
 
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 
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<html>
 
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  <head>
 
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    <title>PyPy Configuration[translation.backendopt.mallocs] </title>
 
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    <meta content="text/html;charset=ISO-8859-1" name="Content-Type"/>
 
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    <link href="../style.css" media="screen" rel="stylesheet" type="text/css"/></head>
 
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  <body>
 
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    <div><a><img alt="PyPy" height="110" id="pyimg" src="http://codespeak.net/pypy/img/py-web1.png" width="149"/></a></div>
 
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    <div id="metaspace">
 
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      <div class="project_title">PyPy Configuration[translation.backendopt.mallocs] </div>
 
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      <div id="menubar"><a class="menu" href="../index.html">general documentation</a> <a class="menu" href="index.html">config index</a> <a class="menu" href="commandline.html">command-line overview</a>  </div></div>
 
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    <div id="contentspace">
 
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      <div id="docinfoline">
 
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        <div style="float: right; font-style: italic;"> </div></div>
 
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<div class="document" id="translation-backendopt-mallocs">
 
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<h1 class="title">translation.backendopt.mallocs</h1>
 
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<div class="contents topic">
 
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<p class="topic-title first"><a id="contents" name="contents">Contents</a></p>
 
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<ul class="simple">
 
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<li><a class="reference" href="#basic-option-information" id="id1" name="id1">Basic Option Information</a></li>
 
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<li><a class="reference" href="#description" id="id2" name="id2">Description</a></li>
 
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</ul>
 
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</div>
 
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<p><a class="reference" href="translation.backendopt.html">back to parent</a></p>
 
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<div class="section">
 
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<h1><a class="toc-backref" href="#id1" id="basic-option-information" name="basic-option-information">Basic Option Information</a></h1>
 
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<ul class="simple">
 
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<li><strong>name:</strong> mallocs</li>
 
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<li><strong>description:</strong> Remove mallocs</li>
 
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<li><strong>command-line:</strong> --translation-backendopt-mallocs</li>
 
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<li><strong>command-line for negation:</strong> --no-translation-backendopt-mallocs</li>
 
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<li><strong>option type:</strong> boolean option</li>
 
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<li><strong>default:</strong> True</li>
 
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</ul>
 
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</div>
 
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<div class="section">
 
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<h1><a class="toc-backref" href="#id2" id="description" name="description">Description</a></h1>
 
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<p>This optimization enables &quot;malloc removal&quot;, which &quot;explodes&quot;
 
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allocations of structures which do not escape from the function they
 
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are allocated in into one or more additional local variables.</p>
 
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<p>An example.  Consider this rather unlikely seeming code:</p>
 
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<pre class="literal-block">
 
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class C:
 
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    pass
 
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def f(y):
 
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    c = C()
 
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    c.x = y
 
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    return c.x
 
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</pre>
 
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<p>Malloc removal will spot that the <tt class="docutils literal"><span class="pre">C</span></tt> object can never leave <tt class="docutils literal"><span class="pre">f</span></tt>
 
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and replace the above with code like this:</p>
 
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<pre class="literal-block">
 
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def f(y):
 
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    _c__x = y
 
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    return _c__x
 
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</pre>
 
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<p>It is rare for code to be directly written in a way that allows this
 
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optimization to be useful, but inlining often results in opportunities
 
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for its use (and indeed, this is one of the main reasons PyPy does its
 
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own inlining rather than relying on the C compilers).</p>
 
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<p>For much more information about this and other optimizations you can
 
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read section 4.1 of the technical report on &quot;Massive Parallelism and
 
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Translation Aspects&quot; which you can find on the <a class="reference" href="../index-report.html">Technical reports page</a>.</p>
 
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</div>
 
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</div>
 
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</div></body></html>
 
 
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