<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="generator" content="Asciidoctor 2.0.23">
<title>IntroduceLoops</title>
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Open+Sans:300,300italic,400,400italic,600,600italic%7CNoto+Serif:400,400italic,700,700italic%7CDroid+Sans+Mono:400,700">
<link rel="stylesheet" href="./asciidoctor.css">
<link rel="stylesheet" href="./mlton.css">

</head>
<body class="article">
<div id="mlton-header">
<div id="mlton-header-text">
<h2>
<a href="./Home">
MLton
20241230
</a>
</h2>
</div>
</div>
<div id="header">
<h1>IntroduceLoops</h1>
</div>
<div id="content">
<div id="preamble">
<div class="sectionbody">
<div class="paragraph">
<p><a href="#">IntroduceLoops</a> is an optimization pass for the <a href="SSA">SSA</a>
<a href="IntermediateLanguage">IntermediateLanguage</a>, invoked from <a href="SSASimplify">SSASimplify</a>.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_description">Description</h2>
<div class="sectionbody">
<div class="paragraph">
<p>This pass rewrites any <a href="SSA">SSA</a> function that calls itself in tail
position into one with a local loop and no self tail calls.</p>
</div>
<div class="paragraph">
<p>A <a href="SSA">SSA</a> function like</p>
</div>
<div class="listingblock">
<div class="content">
<pre>fun F (arg_0, arg_1) = L_0 ()
  ...
  L_16 (x_0)
    ...
    F (z_0, z_1) Tail
  ...</pre>
</div>
</div>
<div class="paragraph">
<p>becomes</p>
</div>
<div class="listingblock">
<div class="content">
<pre>fun F (arg_0', arg_1') = loopS_0 ()
  loopS_0 ()
    loop_0 (arg_0', arg_1')
  loop_0 (arg_0, arg_1)
    L_0 ()
  ...
  L_16 (x_0)
    ...
    loop_0 (z_0, z_1)
  ...</pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_implementation">Implementation</h2>
<div class="sectionbody">
<div class="ulist">
<ul>
<li>
<p><a href="https://github.com/MLton/mlton/blob/master/mlton/ssa/introduce-loops.fun"><code>introduce-loops.fun</code></a></p>
</li>
</ul>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_details_and_notes">Details and Notes</h2>
<div class="sectionbody">
<div class="paragraph">
<p></p>
</div>
</div>
</div>
</div>
<div id="mlton-footer">
<div id="mlton-footer-text">
<div>
Last updated Thu Oct 21 15:53:06 2021 -0400 by Matthew Fluet.
<a href="https://github.com/MLton/mlton/commits/master/doc/guide/src/IntroduceLoops.adoc">Log</a>
<a href="https://github.com/MLton/mlton/edit/master/doc/guide/src/IntroduceLoops.adoc">Edit</a>
</div>
</div>
</body>
</html>