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<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="API documentation for the Rust `crunchy` crate."><meta name="keywords" content="rust, rustlang, rust-lang, crunchy"><title>crunchy - Rust</title><link rel="stylesheet" type="text/css" href="../normalize.css"><link rel="stylesheet" type="text/css" href="../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../dark.css"><link rel="stylesheet" type="text/css" href="../light.css" id="themeStyle"><script src="../storage.js"></script></head><body class="rustdoc mod"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><p class='location'>Crate crunchy</p><div class="sidebar-elems"><div class="block items"><ul><li><a href="#macros">Macros</a></li></ul></div><p class='location'></p><script>window.sidebarCurrent = {name: 'crunchy', ty: 'mod', relpath: '../'};</script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><input class="search-input" name="search" autocomplete="off" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><a id="settings-menu" href="../settings.html"><img src="../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='in-band'>Crate <a class="mod" href=''>crunchy</a></span><span class='out-of-band'><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>−</span>]</a></span><a class='srclink' href='../src/crunchy/lib.rs.html#1-36' title='goto source code'>[src]</a></span></h1><div class='docblock'><p>The crunchy unroller - deterministically unroll constant loops. For number "crunching".</p>
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<p>The Rust optimizer will unroll constant loops that don't use the loop variable, like this:</p>
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<div class='information'><div class='tooltip ignore'>ⓘ<span class='tooltiptext'>This example is not tested</span></div></div><pre class="rust rust-example-rendered ignore">
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<span class="kw">for</span> <span class="kw">_</span> <span class="kw">in</span> <span class="number">0</span>..<span class="number">100</span> {
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<span class="macro">println</span><span class="macro">!</span>(<span class="string">"Hello!"</span>);
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}</pre>
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<p>However, using the loop variable will cause it to never unroll the loop. This is unfortunate because it means that you can't
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constant-fold the loop variable, and if you end up stomping on the registers it will have to do a load for each iteration.
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This crate ensures that your code is unrolled and const-folded. It only works on literals,
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unfortunately, but there's a work-around:</p>
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<div class='information'><div class='tooltip ignore'>ⓘ<span class='tooltiptext'>This example is not tested</span></div></div><pre class="rust rust-example-rendered ignore">
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<span class="macro">debug_assert_eq</span><span class="macro">!</span>(<span class="ident">MY_CONSTANT</span>, <span class="number">100</span>);
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<span class="macro">unroll</span><span class="macro">!</span> {
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<span class="kw">for</span> <span class="ident">i</span> <span class="kw">in</span> <span class="number">0</span>..<span class="number">100</span> {
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<span class="macro">println</span><span class="macro">!</span>(<span class="string">"Iteration {}"</span>, <span class="ident">i</span>);
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}
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}</pre>
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<p>This means that your tests will catch if you redefine the constant.</p>
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<p>To default maximum number of loops to unroll is <code>64</code>, but that can be easily increased using the cargo features:</p>
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<ul>
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<li><code>limit_128</code></li>
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<li><code>limit_256</code></li>
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<li><code>limit_512</code></li>
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<li><code>limit_1024</code></li>
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<li><code>limit_2048</code></li>
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</ul>
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</div><h2 id='macros' class='section-header'><a href="#macros">Macros</a></h2>
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<table>
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<tr class=' module-item'>
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<td><a class="macro" href="macro.unroll.html"
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title='macro crunchy::unroll'>unroll</a></td>
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<td class='docblock-short'>
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<p>Unroll the given for loop</p>
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</td>
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</tr></table></section><section id="search" class="content hidden"></section><section class="footer"></section><aside id="help" class="hidden"><div><h1 class="hidden">Help</h1><div class="shortcuts"><h2>Keyboard Shortcuts</h2><dl><dt><kbd>?</kbd></dt><dd>Show this help dialog</dd><dt><kbd>S</kbd></dt><dd>Focus the search field</dd><dt><kbd>↑</kbd></dt><dd>Move up in search results</dd><dt><kbd>↓</kbd></dt><dd>Move down in search results</dd><dt><kbd>↹</kbd></dt><dd>Switch tab</dd><dt><kbd>⏎</kbd></dt><dd>Go to active search result</dd><dt><kbd>+</kbd></dt><dd>Expand all sections</dd><dt><kbd>-</kbd></dt><dd>Collapse all sections</dd></dl></div><div class="infos"><h2>Search Tricks</h2><p>Prefix searches with a type followed by a colon (e.g. <code>fn:</code>) to restrict the search to a given type.</p><p>Accepted types are: <code>fn</code>, <code>mod</code>, <code>struct</code>, <code>enum</code>, <code>trait</code>, <code>type</code>, <code>macro</code>, and <code>const</code>.</p><p>Search functions by type signature (e.g. <code>vec -> usize</code> or <code>* -> vec</code>)</p><p>Search multiple things at once by splitting your query with comma (e.g. <code>str,u8</code> or <code>String,struct:Vec,test</code>)</p></div></div></aside><script>window.rootPath = "../";window.currentCrate = "crunchy";</script><script src="../aliases.js"></script><script src="../main.js"></script><script defer src="../search-index.js"></script></body></html> |