<!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="Source of the Rust file `src/codegen.rs`."><title>codegen.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceSerif4-Bold-a2c9cd1067f8b328.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../../static.files/rustdoc-cb6f1f67f1bcd037.css" id="mainThemeStyle"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="llvm_kaleidoscope_rs" data-themes="" data-resource-suffix="" data-rustdoc-version="1.73.0 (cc66ad468 2023-10-03)" data-channel="1.73.0" data-search-js="search-6dfdfced5eff6596.js" data-settings-js="settings-de11bff964e9d4e5.js" data-settings-css="settings-8c76f75bfb6bd192.css" data-theme-light-css="light-1596385f77d47ef2.css" data-theme-dark-css="dark-0a43001d3fc2282c.css" data-theme-ayu-css="ayu-fd19013d6ce078bf.css" ><script src="../../static.files/storage-db41da1a38ea3cb8.js"></script><script defer src="../../static.files/src-script-3280b574d94e47b4.js"></script><script defer src="../../src-files.js"></script><script defer src="../../static.files/main-0795b7d26be81095.js"></script><noscript><link rel="stylesheet" media="(prefers-color-scheme:light)" href="../../static.files/light-1596385f77d47ef2.css"><link rel="stylesheet" media="(prefers-color-scheme:dark)" href="../../static.files/dark-0a43001d3fc2282c.css"><link rel="stylesheet" href="../../static.files/noscript-cffde32267a19fd6.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-16x16-8b506e7a72182f1c.png"><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-2c020d218678b618.svg"></head><body class="rustdoc src"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"></nav><main><nav class="sub"><a class="sub-logo-container" href="../../llvm_kaleidoscope_rs/index.html"><img class="rust-logo" src="../../static.files/rust-logo-151179464ae7ed46.svg" alt="logo"></a><form class="search-form"><span></span><input class="search-input" name="search" aria-label="Run search in the documentation" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><div data-nosnippet><pre class="src-line-numbers"><a href="#1" id="1">1</a>
<a href="#2" id="2">2</a>
<a href="#3" id="3">3</a>
<a href="#4" id="4">4</a>
<a href="#5" id="5">5</a>
<a href="#6" id="6">6</a>
<a href="#7" id="7">7</a>
<a href="#8" id="8">8</a>
<a href="#9" id="9">9</a>
<a href="#10" id="10">10</a>
<a href="#11" id="11">11</a>
<a href="#12" id="12">12</a>
<a href="#13" id="13">13</a>
<a href="#14" id="14">14</a>
<a href="#15" id="15">15</a>
<a href="#16" id="16">16</a>
<a href="#17" id="17">17</a>
<a href="#18" id="18">18</a>
<a href="#19" id="19">19</a>
<a href="#20" id="20">20</a>
<a href="#21" id="21">21</a>
<a href="#22" id="22">22</a>
<a href="#23" id="23">23</a>
<a href="#24" id="24">24</a>
<a href="#25" id="25">25</a>
<a href="#26" id="26">26</a>
<a href="#27" id="27">27</a>
<a href="#28" id="28">28</a>
<a href="#29" id="29">29</a>
<a href="#30" id="30">30</a>
<a href="#31" id="31">31</a>
<a href="#32" id="32">32</a>
<a href="#33" id="33">33</a>
<a href="#34" id="34">34</a>
<a href="#35" id="35">35</a>
<a href="#36" id="36">36</a>
<a href="#37" id="37">37</a>
<a href="#38" id="38">38</a>
<a href="#39" id="39">39</a>
<a href="#40" id="40">40</a>
<a href="#41" id="41">41</a>
<a href="#42" id="42">42</a>
<a href="#43" id="43">43</a>
<a href="#44" id="44">44</a>
<a href="#45" id="45">45</a>
<a href="#46" id="46">46</a>
<a href="#47" id="47">47</a>
<a href="#48" id="48">48</a>
<a href="#49" id="49">49</a>
<a href="#50" id="50">50</a>
<a href="#51" id="51">51</a>
<a href="#52" id="52">52</a>
<a href="#53" id="53">53</a>
<a href="#54" id="54">54</a>
<a href="#55" id="55">55</a>
<a href="#56" id="56">56</a>
<a href="#57" id="57">57</a>
<a href="#58" id="58">58</a>
<a href="#59" id="59">59</a>
<a href="#60" id="60">60</a>
<a href="#61" id="61">61</a>
<a href="#62" id="62">62</a>
<a href="#63" id="63">63</a>
<a href="#64" id="64">64</a>
<a href="#65" id="65">65</a>
<a href="#66" id="66">66</a>
<a href="#67" id="67">67</a>
<a href="#68" id="68">68</a>
<a href="#69" id="69">69</a>
<a href="#70" id="70">70</a>
<a href="#71" id="71">71</a>
<a href="#72" id="72">72</a>
<a href="#73" id="73">73</a>
<a href="#74" id="74">74</a>
<a href="#75" id="75">75</a>
<a href="#76" id="76">76</a>
<a href="#77" id="77">77</a>
<a href="#78" id="78">78</a>
<a href="#79" id="79">79</a>
<a href="#80" id="80">80</a>
<a href="#81" id="81">81</a>
<a href="#82" id="82">82</a>
<a href="#83" id="83">83</a>
<a href="#84" id="84">84</a>
<a href="#85" id="85">85</a>
<a href="#86" id="86">86</a>
<a href="#87" id="87">87</a>
<a href="#88" id="88">88</a>
<a href="#89" id="89">89</a>
<a href="#90" id="90">90</a>
<a href="#91" id="91">91</a>
<a href="#92" id="92">92</a>
<a href="#93" id="93">93</a>
<a href="#94" id="94">94</a>
<a href="#95" id="95">95</a>
<a href="#96" id="96">96</a>
<a href="#97" id="97">97</a>
<a href="#98" id="98">98</a>
<a href="#99" id="99">99</a>
<a href="#100" id="100">100</a>
<a href="#101" id="101">101</a>
<a href="#102" id="102">102</a>
<a href="#103" id="103">103</a>
<a href="#104" id="104">104</a>
<a href="#105" id="105">105</a>
<a href="#106" id="106">106</a>
<a href="#107" id="107">107</a>
<a href="#108" id="108">108</a>
<a href="#109" id="109">109</a>
<a href="#110" id="110">110</a>
<a href="#111" id="111">111</a>
<a href="#112" id="112">112</a>
<a href="#113" id="113">113</a>
<a href="#114" id="114">114</a>
<a href="#115" id="115">115</a>
<a href="#116" id="116">116</a>
<a href="#117" id="117">117</a>
<a href="#118" id="118">118</a>
<a href="#119" id="119">119</a>
<a href="#120" id="120">120</a>
<a href="#121" id="121">121</a>
<a href="#122" id="122">122</a>
<a href="#123" id="123">123</a>
<a href="#124" id="124">124</a>
<a href="#125" id="125">125</a>
<a href="#126" id="126">126</a>
<a href="#127" id="127">127</a>
<a href="#128" id="128">128</a>
<a href="#129" id="129">129</a>
<a href="#130" id="130">130</a>
<a href="#131" id="131">131</a>
<a href="#132" id="132">132</a>
<a href="#133" id="133">133</a>
<a href="#134" id="134">134</a>
<a href="#135" id="135">135</a>
<a href="#136" id="136">136</a>
<a href="#137" id="137">137</a>
<a href="#138" id="138">138</a>
<a href="#139" id="139">139</a>
<a href="#140" id="140">140</a>
<a href="#141" id="141">141</a>
<a href="#142" id="142">142</a>
<a href="#143" id="143">143</a>
<a href="#144" id="144">144</a>
<a href="#145" id="145">145</a>
<a href="#146" id="146">146</a>
<a href="#147" id="147">147</a>
<a href="#148" id="148">148</a>
<a href="#149" id="149">149</a>
<a href="#150" id="150">150</a>
<a href="#151" id="151">151</a>
<a href="#152" id="152">152</a>
<a href="#153" id="153">153</a>
<a href="#154" id="154">154</a>
<a href="#155" id="155">155</a>
<a href="#156" id="156">156</a>
<a href="#157" id="157">157</a>
<a href="#158" id="158">158</a>
<a href="#159" id="159">159</a>
<a href="#160" id="160">160</a>
<a href="#161" id="161">161</a>
<a href="#162" id="162">162</a>
<a href="#163" id="163">163</a>
<a href="#164" id="164">164</a>
<a href="#165" id="165">165</a>
<a href="#166" id="166">166</a>
<a href="#167" id="167">167</a>
<a href="#168" id="168">168</a>
<a href="#169" id="169">169</a>
<a href="#170" id="170">170</a>
<a href="#171" id="171">171</a>
<a href="#172" id="172">172</a>
<a href="#173" id="173">173</a>
<a href="#174" id="174">174</a>
<a href="#175" id="175">175</a>
<a href="#176" id="176">176</a>
<a href="#177" id="177">177</a>
<a href="#178" id="178">178</a>
<a href="#179" id="179">179</a>
<a href="#180" id="180">180</a>
<a href="#181" id="181">181</a>
<a href="#182" id="182">182</a>
<a href="#183" id="183">183</a>
<a href="#184" id="184">184</a>
<a href="#185" id="185">185</a>
<a href="#186" id="186">186</a>
<a href="#187" id="187">187</a>
<a href="#188" id="188">188</a>
<a href="#189" id="189">189</a>
<a href="#190" id="190">190</a>
<a href="#191" id="191">191</a>
<a href="#192" id="192">192</a>
<a href="#193" id="193">193</a>
<a href="#194" id="194">194</a>
<a href="#195" id="195">195</a>
<a href="#196" id="196">196</a>
<a href="#197" id="197">197</a>
<a href="#198" id="198">198</a>
<a href="#199" id="199">199</a>
<a href="#200" id="200">200</a>
<a href="#201" id="201">201</a>
<a href="#202" id="202">202</a>
<a href="#203" id="203">203</a>
<a href="#204" id="204">204</a>
<a href="#205" id="205">205</a>
<a href="#206" id="206">206</a>
<a href="#207" id="207">207</a>
<a href="#208" id="208">208</a>
<a href="#209" id="209">209</a>
<a href="#210" id="210">210</a>
<a href="#211" id="211">211</a>
<a href="#212" id="212">212</a>
<a href="#213" id="213">213</a>
<a href="#214" id="214">214</a>
<a href="#215" id="215">215</a>
<a href="#216" id="216">216</a>
<a href="#217" id="217">217</a>
<a href="#218" id="218">218</a>
<a href="#219" id="219">219</a>
<a href="#220" id="220">220</a>
<a href="#221" id="221">221</a>
<a href="#222" id="222">222</a>
<a href="#223" id="223">223</a>
<a href="#224" id="224">224</a>
<a href="#225" id="225">225</a>
<a href="#226" id="226">226</a>
<a href="#227" id="227">227</a>
<a href="#228" id="228">228</a>
<a href="#229" id="229">229</a>
<a href="#230" id="230">230</a>
<a href="#231" id="231">231</a>
<a href="#232" id="232">232</a>
<a href="#233" id="233">233</a>
<a href="#234" id="234">234</a>
<a href="#235" id="235">235</a>
<a href="#236" id="236">236</a>
<a href="#237" id="237">237</a>
<a href="#238" id="238">238</a>
<a href="#239" id="239">239</a>
<a href="#240" id="240">240</a>
<a href="#241" id="241">241</a>
<a href="#242" id="242">242</a>
<a href="#243" id="243">243</a>
<a href="#244" id="244">244</a>
<a href="#245" id="245">245</a>
<a href="#246" id="246">246</a>
<a href="#247" id="247">247</a>
<a href="#248" id="248">248</a>
<a href="#249" id="249">249</a>
<a href="#250" id="250">250</a>
<a href="#251" id="251">251</a>
<a href="#252" id="252">252</a>
<a href="#253" id="253">253</a>
<a href="#254" id="254">254</a>
<a href="#255" id="255">255</a>
<a href="#256" id="256">256</a>
<a href="#257" id="257">257</a>
<a href="#258" id="258">258</a>
<a href="#259" id="259">259</a>
<a href="#260" id="260">260</a>
<a href="#261" id="261">261</a>
<a href="#262" id="262">262</a>
<a href="#263" id="263">263</a>
<a href="#264" id="264">264</a>
<a href="#265" id="265">265</a>
<a href="#266" id="266">266</a>
<a href="#267" id="267">267</a>
<a href="#268" id="268">268</a>
<a href="#269" id="269">269</a>
<a href="#270" id="270">270</a>
<a href="#271" id="271">271</a>
<a href="#272" id="272">272</a>
<a href="#273" id="273">273</a>
<a href="#274" id="274">274</a>
<a href="#275" id="275">275</a>
<a href="#276" id="276">276</a>
<a href="#277" id="277">277</a>
<a href="#278" id="278">278</a>
<a href="#279" id="279">279</a>
<a href="#280" id="280">280</a>
<a href="#281" id="281">281</a>
<a href="#282" id="282">282</a>
<a href="#283" id="283">283</a>
<a href="#284" id="284">284</a>
<a href="#285" id="285">285</a>
<a href="#286" id="286">286</a>
<a href="#287" id="287">287</a>
<a href="#288" id="288">288</a>
<a href="#289" id="289">289</a>
<a href="#290" id="290">290</a>
<a href="#291" id="291">291</a>
<a href="#292" id="292">292</a>
<a href="#293" id="293">293</a>
<a href="#294" id="294">294</a>
<a href="#295" id="295">295</a>
<a href="#296" id="296">296</a>
<a href="#297" id="297">297</a>
<a href="#298" id="298">298</a>
<a href="#299" id="299">299</a>
<a href="#300" id="300">300</a>
<a href="#301" id="301">301</a>
<a href="#302" id="302">302</a>
<a href="#303" id="303">303</a>
<a href="#304" id="304">304</a>
<a href="#305" id="305">305</a>
<a href="#306" id="306">306</a>
<a href="#307" id="307">307</a>
<a href="#308" id="308">308</a>
<a href="#309" id="309">309</a>
<a href="#310" id="310">310</a>
<a href="#311" id="311">311</a>
<a href="#312" id="312">312</a>
<a href="#313" id="313">313</a>
<a href="#314" id="314">314</a>
<a href="#315" id="315">315</a>
<a href="#316" id="316">316</a>
<a href="#317" id="317">317</a>
<a href="#318" id="318">318</a>
<a href="#319" id="319">319</a>
<a href="#320" id="320">320</a>
<a href="#321" id="321">321</a>
<a href="#322" id="322">322</a>
</pre></div><pre class="rust"><code><span class="kw">use </span>std::collections::HashMap;
<span class="kw">use </span><span class="kw">crate</span>::llvm::{FnValue, FunctionPassManager, IRBuilder, Module, Value};
<span class="kw">use </span><span class="kw">crate</span>::parser::{ExprAST, FunctionAST, PrototypeAST};
<span class="kw">use </span><span class="kw">crate</span>::Either;
<span class="kw">type </span>CodegenResult<T> = <span class="prelude-ty">Result</span><T, String>;
<span class="doccomment">/// Code generator from kaleidoscope AST to LLVM IR.
</span><span class="kw">pub struct </span>Codegen<<span class="lifetime">'llvm</span>, <span class="lifetime">'a</span>> {
module: <span class="kw-2">&</span><span class="lifetime">'llvm </span>Module,
builder: <span class="kw-2">&</span><span class="lifetime">'a </span>IRBuilder<<span class="lifetime">'llvm</span>>,
fpm: <span class="kw-2">&</span><span class="lifetime">'a </span>FunctionPassManager<<span class="lifetime">'llvm</span>>,
fn_protos: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>HashMap<String, PrototypeAST>,
}
<span class="kw">impl</span><<span class="lifetime">'llvm</span>, <span class="lifetime">'a</span>> Codegen<<span class="lifetime">'llvm</span>, <span class="lifetime">'a</span>> {
<span class="doccomment">/// Compile either a [`PrototypeAST`] or a [`FunctionAST`] into the LLVM `module`.
</span><span class="kw">pub fn </span>compile(
module: <span class="kw-2">&</span><span class="lifetime">'llvm </span>Module,
fn_protos: <span class="kw-2">&mut </span>HashMap<String, PrototypeAST>,
compilee: Either<<span class="kw-2">&</span>PrototypeAST, <span class="kw-2">&</span>FunctionAST>,
) -> CodegenResult<FnValue<<span class="lifetime">'llvm</span>>> {
<span class="kw">let </span><span class="kw-2">mut </span>cg = Codegen {
module,
builder: <span class="kw-2">&</span>IRBuilder::with_ctx(module),
fpm: <span class="kw-2">&</span>FunctionPassManager::with_ctx(module),
fn_protos,
};
<span class="kw">let </span><span class="kw-2">mut </span>variables = HashMap::new();
<span class="kw">match </span>compilee {
Either::A(proto) => <span class="prelude-val">Ok</span>(cg.codegen_prototype(proto)),
Either::B(func) => cg.codegen_function(func, <span class="kw-2">&mut </span>variables),
}
}
<span class="kw">fn </span>codegen_expr(
<span class="kw-2">&</span><span class="self">self</span>,
expr: <span class="kw-2">&</span>ExprAST,
named_values: <span class="kw-2">&mut </span>HashMap<String, Value<<span class="lifetime">'llvm</span>>>,
) -> CodegenResult<Value<<span class="lifetime">'llvm</span>>> {
<span class="kw">match </span>expr {
ExprAST::Number(num) => <span class="prelude-val">Ok</span>(<span class="self">self</span>.module.type_f64().const_f64(<span class="kw-2">*</span>num)),
ExprAST::Variable(name) => <span class="kw">match </span>named_values.get(name.as_str()) {
<span class="prelude-val">Some</span>(value) => <span class="prelude-val">Ok</span>(<span class="kw-2">*</span>value),
<span class="prelude-val">None </span>=> <span class="prelude-val">Err</span>(<span class="string">"Unknown variable name"</span>.into()),
},
ExprAST::Binary(binop, lhs, rhs) => {
<span class="kw">let </span>l = <span class="self">self</span>.codegen_expr(lhs, named_values)<span class="question-mark">?</span>;
<span class="kw">let </span>r = <span class="self">self</span>.codegen_expr(rhs, named_values)<span class="question-mark">?</span>;
<span class="kw">match </span>binop {
<span class="string">'+' </span>=> <span class="prelude-val">Ok</span>(<span class="self">self</span>.builder.fadd(l, r)),
<span class="string">'-' </span>=> <span class="prelude-val">Ok</span>(<span class="self">self</span>.builder.fsub(l, r)),
<span class="string">'*' </span>=> <span class="prelude-val">Ok</span>(<span class="self">self</span>.builder.fmul(l, r)),
<span class="string">'<' </span>=> {
<span class="kw">let </span>res = <span class="self">self</span>.builder.fcmpult(l, r);
<span class="comment">// Turn bool into f64.
</span><span class="prelude-val">Ok</span>(<span class="self">self</span>.builder.uitofp(res, <span class="self">self</span>.module.type_f64()))
}
<span class="kw">_ </span>=> <span class="prelude-val">Err</span>(<span class="string">"invalid binary operator"</span>.into()),
}
}
ExprAST::Call(callee, args) => <span class="kw">match </span><span class="self">self</span>.get_function(callee) {
<span class="prelude-val">Some</span>(callee) => {
<span class="kw">if </span>callee.args() != args.len() {
<span class="kw">return </span><span class="prelude-val">Err</span>(<span class="string">"Incorrect # arguments passed"</span>.into());
}
<span class="comment">// Generate code for function argument expressions.
</span><span class="kw">let </span><span class="kw-2">mut </span>args: Vec<Value<<span class="lifetime">'_</span>>> = args
.iter()
.map(|arg| <span class="self">self</span>.codegen_expr(arg, named_values))
.collect::<CodegenResult<<span class="kw">_</span>>>()<span class="question-mark">?</span>;
<span class="prelude-val">Ok</span>(<span class="self">self</span>.builder.call(callee, <span class="kw-2">&mut </span>args))
}
<span class="prelude-val">None </span>=> <span class="prelude-val">Err</span>(<span class="string">"Unknown function referenced"</span>.into()),
},
ExprAST::If { cond, then, else_ } => {
<span class="comment">// For 'if' expressions we are building the following CFG.
//
// ; cond
// br
// |
// +-----+------+
// v v
// ; then ; else
// | |
// +-----+------+
// v
// ; merge
// phi then, else
// ret phi
</span><span class="kw">let </span>cond_v = {
<span class="comment">// Codgen 'cond' expression.
</span><span class="kw">let </span>v = <span class="self">self</span>.codegen_expr(cond, named_values)<span class="question-mark">?</span>;
<span class="comment">// Compare 'v' against '0' as 'one = ordered not equal'.
</span><span class="self">self</span>.builder
.fcmpone(v, <span class="self">self</span>.module.type_f64().const_f64(<span class="number">0f64</span>))
};
<span class="comment">// Get the function we are currently inserting into.
</span><span class="kw">let </span>the_function = <span class="self">self</span>.builder.get_insert_block().get_parent();
<span class="comment">// Create basic blocks for the 'then' / 'else' expressions as well as the return
// instruction ('merge').
//
// Append the 'then' basic block to the function, don't insert the 'else' and
// 'merge' basic blocks yet.
</span><span class="kw">let </span>then_bb = <span class="self">self</span>.module.append_basic_block(the_function);
<span class="kw">let </span>else_bb = <span class="self">self</span>.module.create_basic_block();
<span class="kw">let </span>merge_bb = <span class="self">self</span>.module.create_basic_block();
<span class="comment">// Create a conditional branch based on the result of the 'cond' expression.
</span><span class="self">self</span>.builder.cond_br(cond_v, then_bb, else_bb);
<span class="comment">// Move to 'then' basic block and codgen the 'then' expression.
</span><span class="self">self</span>.builder.pos_at_end(then_bb);
<span class="kw">let </span>then_v = <span class="self">self</span>.codegen_expr(then, named_values)<span class="question-mark">?</span>;
<span class="comment">// Create unconditional branch to 'merge' block.
</span><span class="self">self</span>.builder.br(merge_bb);
<span class="comment">// Update reference to current basic block (in case the 'then' expression added new
// basic blocks).
</span><span class="kw">let </span>then_bb = <span class="self">self</span>.builder.get_insert_block();
<span class="comment">// Now append the 'else' basic block to the function.
</span>the_function.append_basic_block(else_bb);
<span class="comment">// Move to 'else' basic block and codgen the 'else' expression.
</span><span class="self">self</span>.builder.pos_at_end(else_bb);
<span class="kw">let </span>else_v = <span class="self">self</span>.codegen_expr(else_, named_values)<span class="question-mark">?</span>;
<span class="comment">// Create unconditional branch to 'merge' block.
</span><span class="self">self</span>.builder.br(merge_bb);
<span class="comment">// Update reference to current basic block (in case the 'else' expression added new
// basic blocks).
</span><span class="kw">let </span>else_bb = <span class="self">self</span>.builder.get_insert_block();
<span class="comment">// Now append the 'merge' basic block to the function.
</span>the_function.append_basic_block(merge_bb);
<span class="comment">// Move to 'merge' basic block.
</span><span class="self">self</span>.builder.pos_at_end(merge_bb);
<span class="comment">// Codegen the phi node returning the appropriate value depending on the branch
// condition.
</span><span class="kw">let </span>phi = <span class="self">self</span>.builder.phi(
<span class="self">self</span>.module.type_f64(),
<span class="kw-2">&</span>[(then_v, then_bb), (else_v, else_bb)],
);
<span class="prelude-val">Ok</span>(<span class="kw-2">*</span>phi)
}
ExprAST::For {
var,
start,
end,
step,
body,
} => {
<span class="comment">// For 'for' expression we build the following structure.
//
// entry:
// init = start expression
// br loop
// loop:
// i = phi [%init, %entry], [%new_i, %loop]
// ; loop body ...
// new_i = increment %i by step expression
// ; check end condition and branch
// end:
// Compute initial value for the loop variable.
</span><span class="kw">let </span>start_val = <span class="self">self</span>.codegen_expr(start, named_values)<span class="question-mark">?</span>;
<span class="kw">let </span>the_function = <span class="self">self</span>.builder.get_insert_block().get_parent();
<span class="comment">// Get current basic block (used in the loop variable phi node).
</span><span class="kw">let </span>entry_bb = <span class="self">self</span>.builder.get_insert_block();
<span class="comment">// Add new basic block to emit loop body.
</span><span class="kw">let </span>loop_bb = <span class="self">self</span>.module.append_basic_block(the_function);
<span class="self">self</span>.builder.br(loop_bb);
<span class="self">self</span>.builder.pos_at_end(loop_bb);
<span class="comment">// Build phi not to pick loop variable in case we come from the 'entry' block.
// Which is the case when we enter the loop for the first time.
// We will add another incoming value once we computed the updated loop variable
// below.
</span><span class="kw">let </span>variable = <span class="self">self
</span>.builder
.phi(<span class="self">self</span>.module.type_f64(), <span class="kw-2">&</span>[(start_val, entry_bb)]);
<span class="comment">// Insert the loop variable into the named values map that it can be referenced
// from the body as well as the end condition.
// In case the loop variable shadows an existing variable remember the shared one.
</span><span class="kw">let </span>old_val = named_values.insert(var.into(), <span class="kw-2">*</span>variable);
<span class="comment">// Generate the loop body.
</span><span class="self">self</span>.codegen_expr(body, named_values)<span class="question-mark">?</span>;
<span class="comment">// Generate step value expression if available else use '1'.
</span><span class="kw">let </span>step_val = <span class="kw">if let </span><span class="prelude-val">Some</span>(step) = step {
<span class="self">self</span>.codegen_expr(step, named_values)<span class="question-mark">?
</span>} <span class="kw">else </span>{
<span class="self">self</span>.module.type_f64().const_f64(<span class="number">1f64</span>)
};
<span class="comment">// Increment loop variable.
</span><span class="kw">let </span>next_var = <span class="self">self</span>.builder.fadd(<span class="kw-2">*</span>variable, step_val);
<span class="comment">// Generate the loop end condition.
</span><span class="kw">let </span>end_cond = <span class="self">self</span>.codegen_expr(end, named_values)<span class="question-mark">?</span>;
<span class="kw">let </span>end_cond = <span class="self">self
</span>.builder
.fcmpone(end_cond, <span class="self">self</span>.module.type_f64().const_f64(<span class="number">0f64</span>));
<span class="comment">// Get current basic block.
</span><span class="kw">let </span>loop_end_bb = <span class="self">self</span>.builder.get_insert_block();
<span class="comment">// Add new basic block following the loop.
</span><span class="kw">let </span>after_bb = <span class="self">self</span>.module.append_basic_block(the_function);
<span class="comment">// Register additional incoming value for the loop variable. This will choose the
// updated loop variable if we are iterating in the loop.
</span>variable.add_incoming(next_var, loop_end_bb);
<span class="comment">// Branch depending on the loop end condition.
</span><span class="self">self</span>.builder.cond_br(end_cond, loop_bb, after_bb);
<span class="self">self</span>.builder.pos_at_end(after_bb);
<span class="comment">// Restore the shadowed variable if there was one.
</span><span class="kw">if let </span><span class="prelude-val">Some</span>(old_val) = old_val {
<span class="comment">// We inserted 'var' above so it must exist.
</span><span class="kw-2">*</span>named_values.get_mut(var).unwrap() = old_val;
} <span class="kw">else </span>{
named_values.remove(var);
}
<span class="comment">// Loops just always return 0.
</span><span class="prelude-val">Ok</span>(<span class="self">self</span>.module.type_f64().const_f64(<span class="number">0f64</span>))
}
}
}
<span class="kw">fn </span>codegen_prototype(<span class="kw-2">&</span><span class="self">self</span>, PrototypeAST(name, args): <span class="kw-2">&</span>PrototypeAST) -> FnValue<<span class="lifetime">'llvm</span>> {
<span class="kw">let </span>type_f64 = <span class="self">self</span>.module.type_f64();
<span class="kw">let </span><span class="kw-2">mut </span>doubles = Vec::new();
doubles.resize(args.len(), type_f64);
<span class="comment">// Build the function type: fn(f64, f64, ..) -> f64
</span><span class="kw">let </span>ft = <span class="self">self</span>.module.type_fn(<span class="kw-2">&mut </span>doubles, type_f64);
<span class="comment">// Create the function declaration.
</span><span class="kw">let </span>f = <span class="self">self</span>.module.add_fn(name, ft);
<span class="comment">// Set the names of the function arguments.
</span><span class="kw">for </span>idx <span class="kw">in </span><span class="number">0</span>..f.args() {
f.arg(idx).set_name(<span class="kw-2">&</span>args[idx]);
}
f
}
<span class="kw">fn </span>codegen_function(
<span class="kw-2">&mut </span><span class="self">self</span>,
FunctionAST(proto, body): <span class="kw-2">&</span>FunctionAST,
named_values: <span class="kw-2">&mut </span>HashMap<String, Value<<span class="lifetime">'llvm</span>>>,
) -> CodegenResult<FnValue<<span class="lifetime">'llvm</span>>> {
<span class="comment">// Insert the function prototype into the `fn_protos` map to keep track for re-generating
// declarations in other modules.
</span><span class="self">self</span>.fn_protos.insert(proto.<span class="number">0</span>.clone(), proto.clone());
<span class="kw">let </span>the_function = <span class="self">self</span>.get_function(<span class="kw-2">&</span>proto.<span class="number">0</span>)
.expect(<span class="string">"If proto not already generated, get_function will do for us since we updated fn_protos before-hand!"</span>);
<span class="kw">if </span>the_function.basic_blocks() > <span class="number">0 </span>{
<span class="kw">return </span><span class="prelude-val">Err</span>(<span class="string">"Function cannot be redefined."</span>.into());
}
<span class="comment">// Create entry basic block to insert code.
</span><span class="kw">let </span>bb = <span class="self">self</span>.module.append_basic_block(the_function);
<span class="self">self</span>.builder.pos_at_end(bb);
<span class="comment">// New scope, clear the map with the function args.
</span>named_values.clear();
<span class="comment">// Update the map with the current functions args.
</span><span class="kw">for </span>idx <span class="kw">in </span><span class="number">0</span>..the_function.args() {
<span class="kw">let </span>arg = the_function.arg(idx);
named_values.insert(arg.get_name().into(), arg);
}
<span class="comment">// Codegen function body.
</span><span class="kw">if let </span><span class="prelude-val">Ok</span>(ret) = <span class="self">self</span>.codegen_expr(body, named_values) {
<span class="self">self</span>.builder.ret(ret);
<span class="macro">assert!</span>(the_function.verify());
<span class="comment">// Run the optimization passes on the function.
</span><span class="self">self</span>.fpm.run(the_function);
<span class="prelude-val">Ok</span>(the_function)
} <span class="kw">else </span>{
<span class="macro">todo!</span>(<span class="string">"Failed to codegen function body, erase from module!"</span>);
}
}
<span class="doccomment">/// Lookup function with `name` in the LLVM module and return the corresponding value reference.
/// If the function is not available in the module, check if the prototype is known and codegen
/// it.
/// Return [`None`] if the prototype is not known.
</span><span class="kw">fn </span>get_function(<span class="kw-2">&</span><span class="self">self</span>, name: <span class="kw-2">&</span>str) -> <span class="prelude-ty">Option</span><FnValue<<span class="lifetime">'llvm</span>>> {
<span class="kw">let </span>callee = <span class="kw">match </span><span class="self">self</span>.module.get_fn(name) {
<span class="prelude-val">Some</span>(callee) => callee,
<span class="prelude-val">None </span>=> {
<span class="kw">let </span>proto = <span class="self">self</span>.fn_protos.get(name)<span class="question-mark">?</span>;
<span class="self">self</span>.codegen_prototype(proto)
}
};
<span class="prelude-val">Some</span>(callee)
}
}
</code></pre></div></section></main></body></html>
