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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 `wasmer_clif_fork_frontend` crate."><meta name="keywords" content="rust, rustlang, rust-lang, wasmer_clif_fork_frontend"><title>wasmer_clif_fork_frontend - 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><noscript><link rel="stylesheet" href="../noscript.css"></noscript><link rel="shortcut icon" href="../favicon.ico"><style type="text/css">#crate-search{background-image:url("../down-arrow.svg");}</style></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">&#9776;</div><a href='../wasmer_clif_fork_frontend/index.html'><div class='logo-container'><img src='../rust-logo.png' alt='logo'></div></a><p class='location'>Crate wasmer_clif_fork_frontend</p><div class="sidebar-elems"><a id='all-types' href='all.html'><p>See all wasmer_clif_fork_frontend's items</p></a><div class="block items"><ul><li><a href="#structs">Structs</a></li><li><a href="#constants">Constants</a></li></ul></div><p class='location'></p><script>window.sidebarCurrent = {name: 'wasmer_clif_fork_frontend', 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"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><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='out-of-band'><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>&#x2212;</span>]</a></span><a class='srclink' href='../src/wasmer_clif_fork_frontend/lib.rs.html#1-204' title='goto source code'>[src]</a></span><span class='in-band'>Crate <a class="mod" href=''>wasmer_clif_fork_frontend</a></span></h1><div class='docblock'><p>Cranelift IR builder library.</p>
<p>Provides a straightforward way to create a Cranelift IR function and fill it with instructions
corresponding to your source program written in another language.</p>
<p>To get started, create an <a href="struct.FunctionBuilderContext.html"><code>FunctionBuilderContext</code></a> and
pass it as an argument to a <a href="struct.FunctionBuilder.html"><code>FunctionBuilder</code></a>.</p>
<h1 id="mutable-variables-and-cranelift-ir-values" class="section-header"><a href="#mutable-variables-and-cranelift-ir-values">Mutable variables and Cranelift IR values</a></h1>
<p>The most interesting feature of this API is that it provides a single way to deal with all your
variable problems. Indeed, the <a href="struct.FunctionBuilder.html"><code>FunctionBuilder</code></a> struct has a
type <code>Variable</code> that should be an index of your source language variables. Then, through
calling the functions
<a href="struct.FunctionBuilder.html#method.declare_var"><code>declare_var</code></a>,
<a href="struct.FunctionBuilder.html#method.def_var"><code>def_var</code></a> and
<a href="struct.FunctionBuilder.html#method.use_var"><code>use_var</code></a>, the
<a href="struct.FunctionBuilder.html"><code>FunctionBuilder</code></a> will create for you all the Cranelift IR
values corresponding to your variables.</p>
<p>This API has been designed to help you translate your mutable variables into
<a href="https://en.wikipedia.org/wiki/Static_single_assignment_form"><code>SSA</code></a> form.
<a href="struct.FunctionBuilder.html#method.use_var"><code>use_var</code></a> will return the Cranelift IR value
that corresponds to your mutable variable at a precise point in the program. However, if you know
beforehand that one of your variables is defined only once, for instance if it is the result
of an intermediate expression in an expression-based language, then you can translate it
directly by the Cranelift IR value returned by the instruction builder. Using the
<a href="struct.FunctionBuilder.html#method.use_var"><code>use_var</code></a> API for such an immutable variable
would also work but with a slight additional overhead (the SSA algorithm does not know
beforehand if a variable is immutable or not).</p>
<p>The moral is that you should use these three functions to handle all your mutable variables,
even those that are not present in the source code but artifacts of the translation. It is up
to you to keep a mapping between the mutable variables of your language and their <code>Variable</code>
index that is used by Cranelift. Caution: as the <code>Variable</code> is used by Cranelift to index an
array containing information about your mutable variables, when you create a new <code>Variable</code>
with [<code>Variable::new(var_index)</code>] you should make sure that <code>var_index</code> is provided by a
counter incremented by 1 each time you encounter a new mutable variable.</p>
<h1 id="example" class="section-header"><a href="#example">Example</a></h1>
<p>Here is a pseudo-program we want to transform into Cranelift IR:</p>
<pre><code class="language-clif">function(x) {
x, y, z : i32
block0:
y = 2;
z = x + y;
jump block1
block1:
z = z + y;
brnz y, block2;
z = z - x;
return y
block2:
y = y - x
jump block1
}
</code></pre>
<p>Here is how you build the corresponding Cranelift IR function using <code>FunctionBuilderContext</code>:</p>
<div class="example-wrap"><pre class="rust rust-example-rendered">
<span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">cranelift_codegen</span>;
<span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">cranelift_frontend</span>;
<span class="kw">use</span> <span class="ident">cranelift_codegen</span>::<span class="ident">entity</span>::<span class="ident">EntityRef</span>;
<span class="kw">use</span> <span class="ident">cranelift_codegen</span>::<span class="ident">ir</span>::<span class="ident">types</span>::<span class="kw-2">*</span>;
<span class="kw">use</span> <span class="ident">cranelift_codegen</span>::<span class="ident">ir</span>::{<span class="ident">AbiParam</span>, <span class="ident">ExternalName</span>, <span class="ident">Function</span>, <span class="ident">InstBuilder</span>, <span class="ident">Signature</span>};
<span class="kw">use</span> <span class="ident">cranelift_codegen</span>::<span class="ident">isa</span>::<span class="ident">CallConv</span>;
<span class="kw">use</span> <span class="ident">cranelift_codegen</span>::<span class="ident">settings</span>;
<span class="kw">use</span> <span class="ident">cranelift_codegen</span>::<span class="ident">verifier</span>::<span class="ident">verify_function</span>;
<span class="kw">use</span> <span class="ident">cranelift_frontend</span>::{<span class="ident">FunctionBuilder</span>, <span class="ident">FunctionBuilderContext</span>, <span class="ident">Position</span>, <span class="ident">Variable</span>};
<span class="kw">fn</span> <span class="ident">main</span>() {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">sig</span> <span class="op">=</span> <span class="ident">Signature</span>::<span class="ident">new</span>(<span class="ident">CallConv</span>::<span class="ident">SystemV</span>);
<span class="ident">sig</span>.<span class="ident">returns</span>.<span class="ident">push</span>(<span class="ident">AbiParam</span>::<span class="ident">new</span>(<span class="ident">I32</span>));
<span class="ident">sig</span>.<span class="ident">params</span>.<span class="ident">push</span>(<span class="ident">AbiParam</span>::<span class="ident">new</span>(<span class="ident">I32</span>));
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">fn_builder_ctx</span> <span class="op">=</span> <span class="ident">FunctionBuilderContext</span>::<span class="ident">new</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">func</span> <span class="op">=</span> <span class="ident">Function</span>::<span class="ident">with_name_signature</span>(<span class="ident">ExternalName</span>::<span class="ident">user</span>(<span class="number">0</span>, <span class="number">0</span>), <span class="ident">sig</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">position</span> <span class="op">=</span> <span class="ident">Position</span>::<span class="ident">default</span>();
{
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">builder</span> <span class="op">=</span> <span class="ident">FunctionBuilder</span>::<span class="ident">new</span>(<span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="ident">func</span>, <span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="ident">fn_builder_ctx</span>, <span class="kw-2">&amp;</span><span class="kw-2">mut</span> <span class="ident">position</span>);
<span class="kw">let</span> <span class="ident">block0</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">create_ebb</span>();
<span class="kw">let</span> <span class="ident">block1</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">create_ebb</span>();
<span class="kw">let</span> <span class="ident">block2</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">create_ebb</span>();
<span class="kw">let</span> <span class="ident">x</span> <span class="op">=</span> <span class="ident">Variable</span>::<span class="ident">new</span>(<span class="number">0</span>);
<span class="kw">let</span> <span class="ident">y</span> <span class="op">=</span> <span class="ident">Variable</span>::<span class="ident">new</span>(<span class="number">1</span>);
<span class="kw">let</span> <span class="ident">z</span> <span class="op">=</span> <span class="ident">Variable</span>::<span class="ident">new</span>(<span class="number">2</span>);
<span class="ident">builder</span>.<span class="ident">declare_var</span>(<span class="ident">x</span>, <span class="ident">I32</span>);
<span class="ident">builder</span>.<span class="ident">declare_var</span>(<span class="ident">y</span>, <span class="ident">I32</span>);
<span class="ident">builder</span>.<span class="ident">declare_var</span>(<span class="ident">z</span>, <span class="ident">I32</span>);
<span class="ident">builder</span>.<span class="ident">append_ebb_params_for_function_params</span>(<span class="ident">block0</span>);
<span class="ident">builder</span>.<span class="ident">switch_to_block</span>(<span class="ident">block0</span>);
<span class="ident">builder</span>.<span class="ident">seal_block</span>(<span class="ident">block0</span>);
{
<span class="kw">let</span> <span class="ident">tmp</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">ebb_params</span>(<span class="ident">block0</span>)[<span class="number">0</span>]; <span class="comment">// the first function parameter</span>
<span class="ident">builder</span>.<span class="ident">def_var</span>(<span class="ident">x</span>, <span class="ident">tmp</span>);
}
{
<span class="kw">let</span> <span class="ident">tmp</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">ins</span>().<span class="ident">iconst</span>(<span class="ident">I32</span>, <span class="number">2</span>);
<span class="ident">builder</span>.<span class="ident">def_var</span>(<span class="ident">y</span>, <span class="ident">tmp</span>);
}
{
<span class="kw">let</span> <span class="ident">arg1</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">use_var</span>(<span class="ident">x</span>);
<span class="kw">let</span> <span class="ident">arg2</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">use_var</span>(<span class="ident">y</span>);
<span class="kw">let</span> <span class="ident">tmp</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">ins</span>().<span class="ident">iadd</span>(<span class="ident">arg1</span>, <span class="ident">arg2</span>);
<span class="ident">builder</span>.<span class="ident">def_var</span>(<span class="ident">z</span>, <span class="ident">tmp</span>);
}
<span class="ident">builder</span>.<span class="ident">ins</span>().<span class="ident">jump</span>(<span class="ident">block1</span>, <span class="kw-2">&amp;</span>[]);
<span class="ident">builder</span>.<span class="ident">switch_to_block</span>(<span class="ident">block1</span>);
{
<span class="kw">let</span> <span class="ident">arg1</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">use_var</span>(<span class="ident">y</span>);
<span class="kw">let</span> <span class="ident">arg2</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">use_var</span>(<span class="ident">z</span>);
<span class="kw">let</span> <span class="ident">tmp</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">ins</span>().<span class="ident">iadd</span>(<span class="ident">arg1</span>, <span class="ident">arg2</span>);
<span class="ident">builder</span>.<span class="ident">def_var</span>(<span class="ident">z</span>, <span class="ident">tmp</span>);
}
{
<span class="kw">let</span> <span class="ident">arg</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">use_var</span>(<span class="ident">y</span>);
<span class="ident">builder</span>.<span class="ident">ins</span>().<span class="ident">brnz</span>(<span class="ident">arg</span>, <span class="ident">block2</span>, <span class="kw-2">&amp;</span>[]);
}
{
<span class="kw">let</span> <span class="ident">arg1</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">use_var</span>(<span class="ident">z</span>);
<span class="kw">let</span> <span class="ident">arg2</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">use_var</span>(<span class="ident">x</span>);
<span class="kw">let</span> <span class="ident">tmp</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">ins</span>().<span class="ident">isub</span>(<span class="ident">arg1</span>, <span class="ident">arg2</span>);
<span class="ident">builder</span>.<span class="ident">def_var</span>(<span class="ident">z</span>, <span class="ident">tmp</span>);
}
{
<span class="kw">let</span> <span class="ident">arg</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">use_var</span>(<span class="ident">y</span>);
<span class="ident">builder</span>.<span class="ident">ins</span>().<span class="ident">return_</span>(<span class="kw-2">&amp;</span>[<span class="ident">arg</span>]);
}
<span class="ident">builder</span>.<span class="ident">switch_to_block</span>(<span class="ident">block2</span>);
<span class="ident">builder</span>.<span class="ident">seal_block</span>(<span class="ident">block2</span>);
{
<span class="kw">let</span> <span class="ident">arg1</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">use_var</span>(<span class="ident">y</span>);
<span class="kw">let</span> <span class="ident">arg2</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">use_var</span>(<span class="ident">x</span>);
<span class="kw">let</span> <span class="ident">tmp</span> <span class="op">=</span> <span class="ident">builder</span>.<span class="ident">ins</span>().<span class="ident">isub</span>(<span class="ident">arg1</span>, <span class="ident">arg2</span>);
<span class="ident">builder</span>.<span class="ident">def_var</span>(<span class="ident">y</span>, <span class="ident">tmp</span>);
}
<span class="ident">builder</span>.<span class="ident">ins</span>().<span class="ident">jump</span>(<span class="ident">block1</span>, <span class="kw-2">&amp;</span>[]);
<span class="ident">builder</span>.<span class="ident">seal_block</span>(<span class="ident">block1</span>);
<span class="ident">builder</span>.<span class="ident">finalize</span>();
}
<span class="kw">let</span> <span class="ident">flags</span> <span class="op">=</span> <span class="ident">settings</span>::<span class="ident">Flags</span>::<span class="ident">new</span>(<span class="ident">settings</span>::<span class="ident">builder</span>());
<span class="kw">let</span> <span class="ident">res</span> <span class="op">=</span> <span class="ident">verify_function</span>(<span class="kw-2">&amp;</span><span class="ident">func</span>, <span class="kw-2">&amp;</span><span class="ident">flags</span>);
<span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;{}&quot;</span>, <span class="ident">func</span>.<span class="ident">display</span>(<span class="prelude-val">None</span>));
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Err</span>(<span class="ident">errors</span>) <span class="op">=</span> <span class="ident">res</span> {
<span class="macro">panic</span><span class="macro">!</span>(<span class="string">&quot;{}&quot;</span>, <span class="ident">errors</span>);
}
}</pre></div>
</div><h2 id='structs' class='section-header'><a href="#structs">Structs</a></h2>
<table><tr class='module-item'><td><a class="struct" href="struct.Block.html" title='wasmer_clif_fork_frontend::Block struct'>Block</a></td><td class='docblock-short'><p>A opaque reference to a basic block.</p>
</td></tr><tr class='module-item'><td><a class="struct" href="struct.FunctionBuilder.html" title='wasmer_clif_fork_frontend::FunctionBuilder struct'>FunctionBuilder</a></td><td class='docblock-short'><p>Temporary object used to build a single Cranelift IR <code>Function</code>.</p>
</td></tr><tr class='module-item'><td><a class="struct" href="struct.FunctionBuilderContext.html" title='wasmer_clif_fork_frontend::FunctionBuilderContext struct'>FunctionBuilderContext</a></td><td class='docblock-short'><p>Structure used for translating a series of functions into Cranelift IR.</p>
</td></tr><tr class='module-item'><td><a class="struct" href="struct.Position.html" title='wasmer_clif_fork_frontend::Position struct'>Position</a></td><td class='docblock-short'><p>Position</p>
</td></tr><tr class='module-item'><td><a class="struct" href="struct.Switch.html" title='wasmer_clif_fork_frontend::Switch struct'>Switch</a></td><td class='docblock-short'><p>Unlike with <code>br_table</code>, <code>Switch</code> cases may be sparse or non-0-based.
They emit efficient code using branches, jump tables, or a combination of both.</p>
</td></tr><tr class='module-item'><td><a class="struct" href="struct.Variable.html" title='wasmer_clif_fork_frontend::Variable struct'>Variable</a></td><td class='docblock-short'><p>An opaque reference to a variable.</p>
</td></tr></table><h2 id='constants' class='section-header'><a href="#constants">Constants</a></h2>
<table><tr class='module-item'><td><a class="constant" href="constant.VERSION.html" title='wasmer_clif_fork_frontend::VERSION constant'>VERSION</a></td><td class='docblock-short'><p>Version number of this crate.</p>
</td></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>&#9166;</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 = "wasmer_clif_fork_frontend";</script><script src="../aliases.js"></script><script src="../main.js"></script><script defer src="../search-index.js"></script></body></html>
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