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<a href="./Home">MLton 20201002</a>
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<h1>DeadCode</h1>
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<div class="paragraph"><p><a href="DeadCode">DeadCode</a> is an optimization pass for the <a href="CoreML">CoreML</a>
<a href="IntermediateLanguage">IntermediateLanguage</a>, invoked from <a href="CoreMLSimplify">CoreMLSimplify</a>.</p></div>
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<div class="sect1">
<h2 id="_description">Description</h2>
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<div class="paragraph"><p>This pass eliminates declarations from the
<a href="BasisLibrary">Basis Library</a> not needed by the user program.</p></div>
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<h2 id="_implementation">Implementation</h2>
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<div class="ulist"><ul>
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<p>
<a href="https://github.com/MLton/mlton/blob/master/mlton/core-ml/dead-code.sig"><span class="monospaced">dead-code.sig</span></a>
</p>
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<p>
<a href="https://github.com/MLton/mlton/blob/master/mlton/core-ml/dead-code.fun"><span class="monospaced">dead-code.fun</span></a>
</p>
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<h2 id="_details_and_notes">Details and Notes</h2>
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<div class="paragraph"><p>In order to compile small programs rapidly, a pass of dead code
elimination is run in order to eliminate as much of the Basis Library
as possible.  The dead code elimination algorithm used is not safe in
general, and only works because the Basis Library implementation has
special properties:</p></div>
<div class="ulist"><ul>
<li>
<p>
it terminates
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<p>
it performs no I/O
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</ul></div>
<div class="paragraph"><p>The dead code elimination includes the minimal set of
declarations from the Basis Library so that there are no free
variables in the user program (or remaining Basis Library
implementation).  It has a special hack to include all
bindings of the form:</p></div>
<div class="listingblock">
<div class="content"><div class="highlight"><pre><span></span><span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="p">_</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="p">...</span><span class="w"></span>
</pre></div></div></div>
<div class="paragraph"><p>There is an <a href="MLBasisAnnotations">ML Basis annotation</a>,
<span class="monospaced">deadCode true</span>, that governs which code is subject to this unsafe
dead-code elimination.</p></div>
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