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  <div class="section" id="kaleidoscope-compiling-to-object-code">
<h1><span class="section-number">8. </span>Kaleidoscope: Compiling to Object Code<a class="headerlink" href="#kaleidoscope-compiling-to-object-code" title="Permalink to this headline">¶</a></h1>
<div class="contents local topic" id="contents">
<ul class="simple">
<li><p><a class="reference internal" href="#chapter-8-introduction" id="id1">Chapter 8 Introduction</a></p></li>
<li><p><a class="reference internal" href="#choosing-a-target" id="id2">Choosing a target</a></p></li>
<li><p><a class="reference internal" href="#target-machine" id="id3">Target Machine</a></p></li>
<li><p><a class="reference internal" href="#configuring-the-module" id="id4">Configuring the Module</a></p></li>
<li><p><a class="reference internal" href="#emit-object-code" id="id5">Emit Object Code</a></p></li>
<li><p><a class="reference internal" href="#putting-it-all-together" id="id6">Putting It All Together</a></p></li>
<li><p><a class="reference internal" href="#full-code-listing" id="id7">Full Code Listing</a></p></li>
</ul>
</div>
<div class="section" id="chapter-8-introduction">
<h2><a class="toc-backref" href="#id1"><span class="section-number">8.1. </span>Chapter 8 Introduction</a><a class="headerlink" href="#chapter-8-introduction" title="Permalink to this headline">¶</a></h2>
<p>Welcome to Chapter 8 of the “<a class="reference external" href="index.html">Implementing a language with LLVM</a>” tutorial. This chapter describes how to compile our
language down to object files.</p>
</div>
<div class="section" id="choosing-a-target">
<h2><a class="toc-backref" href="#id2"><span class="section-number">8.2. </span>Choosing a target</a><a class="headerlink" href="#choosing-a-target" title="Permalink to this headline">¶</a></h2>
<p>LLVM has native support for cross-compilation. You can compile to the
architecture of your current machine, or just as easily compile for
other architectures. In this tutorial, we’ll target the current
machine.</p>
<p>To specify the architecture that you want to target, we use a string
called a “target triple”. This takes the form
<code class="docutils literal notranslate"><span class="pre">&lt;arch&gt;&lt;sub&gt;-&lt;vendor&gt;-&lt;sys&gt;-&lt;abi&gt;</span></code> (see the <a class="reference external" href="https://clang.llvm.org/docs/CrossCompilation.html#target-triple">cross compilation docs</a>).</p>
<p>As an example, we can see what clang thinks is our current target
triple:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>$ clang --version | grep Target
Target: x86_64-unknown-linux-gnu
</pre></div>
</div>
<p>Running this command may show something different on your machine as
you might be using a different architecture or operating system to me.</p>
<p>Fortunately, we don’t need to hard-code a target triple to target the
current machine. LLVM provides <code class="docutils literal notranslate"><span class="pre">sys::getDefaultTargetTriple</span></code>, which
returns the target triple of the current machine.</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">auto</span> <span class="n">TargetTriple</span> <span class="o">=</span> <span class="n">sys</span><span class="o">::</span><span class="n">getDefaultTargetTriple</span><span class="p">();</span>
</pre></div>
</div>
<p>LLVM doesn’t require us to link in all the target
functionality. For example, if we’re just using the JIT, we don’t need
the assembly printers. Similarly, if we’re only targeting certain
architectures, we can only link in the functionality for those
architectures.</p>
<p>For this example, we’ll initialize all the targets for emitting object
code.</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">InitializeAllTargetInfos</span><span class="p">();</span>
<span class="n">InitializeAllTargets</span><span class="p">();</span>
<span class="n">InitializeAllTargetMCs</span><span class="p">();</span>
<span class="n">InitializeAllAsmParsers</span><span class="p">();</span>
<span class="n">InitializeAllAsmPrinters</span><span class="p">();</span>
</pre></div>
</div>
<p>We can now use our target triple to get a <code class="docutils literal notranslate"><span class="pre">Target</span></code>:</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">Error</span><span class="p">;</span>
<span class="k">auto</span> <span class="n">Target</span> <span class="o">=</span> <span class="n">TargetRegistry</span><span class="o">::</span><span class="n">lookupTarget</span><span class="p">(</span><span class="n">TargetTriple</span><span class="p">,</span> <span class="n">Error</span><span class="p">);</span>

<span class="c1">// Print an error and exit if we couldn&#39;t find the requested target.</span>
<span class="c1">// This generally occurs if we&#39;ve forgotten to initialise the</span>
<span class="c1">// TargetRegistry or we have a bogus target triple.</span>
<span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">Target</span><span class="p">)</span> <span class="p">{</span>
  <span class="n">errs</span><span class="p">()</span> <span class="o">&lt;&lt;</span> <span class="n">Error</span><span class="p">;</span>
  <span class="k">return</span> <span class="mi">1</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
</div>
<div class="section" id="target-machine">
<h2><a class="toc-backref" href="#id3"><span class="section-number">8.3. </span>Target Machine</a><a class="headerlink" href="#target-machine" title="Permalink to this headline">¶</a></h2>
<p>We will also need a <code class="docutils literal notranslate"><span class="pre">TargetMachine</span></code>. This class provides a complete
machine description of the machine we’re targeting. If we want to
target a specific feature (such as SSE) or a specific CPU (such as
Intel’s Sandylake), we do so now.</p>
<p>To see which features and CPUs that LLVM knows about, we can use
<code class="docutils literal notranslate"><span class="pre">llc</span></code>. For example, let’s look at x86:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>$ llvm-as &lt; /dev/null | llc -march=x86 -mattr=help
Available CPUs for this target:

  amdfam10      - Select the amdfam10 processor.
  athlon        - Select the athlon processor.
  athlon-4      - Select the athlon-4 processor.
  ...

Available features for this target:

  16bit-mode            - 16-bit mode (i8086).
  32bit-mode            - 32-bit mode (80386).
  3dnow                 - Enable 3DNow! instructions.
  3dnowa                - Enable 3DNow! Athlon instructions.
  ...
</pre></div>
</div>
<p>For our example, we’ll use the generic CPU without any additional
features, options or relocation model.</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">auto</span> <span class="n">CPU</span> <span class="o">=</span> <span class="s">&quot;generic&quot;</span><span class="p">;</span>
<span class="k">auto</span> <span class="n">Features</span> <span class="o">=</span> <span class="s">&quot;&quot;</span><span class="p">;</span>

<span class="n">TargetOptions</span> <span class="n">opt</span><span class="p">;</span>
<span class="k">auto</span> <span class="n">RM</span> <span class="o">=</span> <span class="n">Optional</span><span class="o">&lt;</span><span class="n">Reloc</span><span class="o">::</span><span class="n">Model</span><span class="o">&gt;</span><span class="p">();</span>
<span class="k">auto</span> <span class="n">TargetMachine</span> <span class="o">=</span> <span class="n">Target</span><span class="o">-&gt;</span><span class="n">createTargetMachine</span><span class="p">(</span><span class="n">TargetTriple</span><span class="p">,</span> <span class="n">CPU</span><span class="p">,</span> <span class="n">Features</span><span class="p">,</span> <span class="n">opt</span><span class="p">,</span> <span class="n">RM</span><span class="p">);</span>
</pre></div>
</div>
</div>
<div class="section" id="configuring-the-module">
<h2><a class="toc-backref" href="#id4"><span class="section-number">8.4. </span>Configuring the Module</a><a class="headerlink" href="#configuring-the-module" title="Permalink to this headline">¶</a></h2>
<p>We’re now ready to configure our module, to specify the target and
data layout. This isn’t strictly necessary, but the <a class="reference external" href="../Frontend/PerformanceTips.html">frontend
performance guide</a> recommends
this. Optimizations benefit from knowing about the target and data
layout.</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">TheModule</span><span class="o">-&gt;</span><span class="n">setDataLayout</span><span class="p">(</span><span class="n">TargetMachine</span><span class="o">-&gt;</span><span class="n">createDataLayout</span><span class="p">());</span>
<span class="n">TheModule</span><span class="o">-&gt;</span><span class="n">setTargetTriple</span><span class="p">(</span><span class="n">TargetTriple</span><span class="p">);</span>
</pre></div>
</div>
</div>
<div class="section" id="emit-object-code">
<h2><a class="toc-backref" href="#id5"><span class="section-number">8.5. </span>Emit Object Code</a><a class="headerlink" href="#emit-object-code" title="Permalink to this headline">¶</a></h2>
<p>We’re ready to emit object code! Let’s define where we want to write
our file to:</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">auto</span> <span class="n">Filename</span> <span class="o">=</span> <span class="s">&quot;output.o&quot;</span><span class="p">;</span>
<span class="n">std</span><span class="o">::</span><span class="n">error_code</span> <span class="n">EC</span><span class="p">;</span>
<span class="n">raw_fd_ostream</span> <span class="nf">dest</span><span class="p">(</span><span class="n">Filename</span><span class="p">,</span> <span class="n">EC</span><span class="p">,</span> <span class="n">sys</span><span class="o">::</span><span class="n">fs</span><span class="o">::</span><span class="n">OF_None</span><span class="p">);</span>

<span class="k">if</span> <span class="p">(</span><span class="n">EC</span><span class="p">)</span> <span class="p">{</span>
  <span class="n">errs</span><span class="p">()</span> <span class="o">&lt;&lt;</span> <span class="s">&quot;Could not open file: &quot;</span> <span class="o">&lt;&lt;</span> <span class="n">EC</span><span class="p">.</span><span class="n">message</span><span class="p">();</span>
  <span class="k">return</span> <span class="mi">1</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Finally, we define a pass that emits object code, then we run that
pass:</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">legacy</span><span class="o">::</span><span class="n">PassManager</span> <span class="n">pass</span><span class="p">;</span>
<span class="k">auto</span> <span class="n">FileType</span> <span class="o">=</span> <span class="n">CGFT_ObjectFile</span><span class="p">;</span>

<span class="k">if</span> <span class="p">(</span><span class="n">TargetMachine</span><span class="o">-&gt;</span><span class="n">addPassesToEmitFile</span><span class="p">(</span><span class="n">pass</span><span class="p">,</span> <span class="n">dest</span><span class="p">,</span> <span class="k">nullptr</span><span class="p">,</span> <span class="n">FileType</span><span class="p">))</span> <span class="p">{</span>
  <span class="n">errs</span><span class="p">()</span> <span class="o">&lt;&lt;</span> <span class="s">&quot;TargetMachine can&#39;t emit a file of this type&quot;</span><span class="p">;</span>
  <span class="k">return</span> <span class="mi">1</span><span class="p">;</span>
<span class="p">}</span>

<span class="n">pass</span><span class="p">.</span><span class="n">run</span><span class="p">(</span><span class="o">*</span><span class="n">TheModule</span><span class="p">);</span>
<span class="n">dest</span><span class="p">.</span><span class="n">flush</span><span class="p">();</span>
</pre></div>
</div>
</div>
<div class="section" id="putting-it-all-together">
<h2><a class="toc-backref" href="#id6"><span class="section-number">8.6. </span>Putting It All Together</a><a class="headerlink" href="#putting-it-all-together" title="Permalink to this headline">¶</a></h2>
<p>Does it work? Let’s give it a try. We need to compile our code, but
note that the arguments to <code class="docutils literal notranslate"><span class="pre">llvm-config</span></code> are different to the previous chapters.</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>$ clang++ -g -O3 toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs all` -o toy
</pre></div>
</div>
<p>Let’s run it, and define a simple <code class="docutils literal notranslate"><span class="pre">average</span></code> function. Press Ctrl-D
when you’re done.</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>$ ./toy
ready&gt; def average(x y) (x + y) * 0.5;
^D
Wrote output.o
</pre></div>
</div>
<p>We have an object file! To test it, let’s write a simple program and
link it with our output. Here’s the source code:</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span> <span class="cpf">&lt;iostream&gt;</span><span class="cp"></span>

<span class="k">extern</span> <span class="s">&quot;C&quot;</span> <span class="p">{</span>
    <span class="kt">double</span> <span class="nf">average</span><span class="p">(</span><span class="kt">double</span><span class="p">,</span> <span class="kt">double</span><span class="p">);</span>
<span class="p">}</span>

<span class="kt">int</span> <span class="n">main</span><span class="p">()</span> <span class="p">{</span>
    <span class="n">std</span><span class="o">::</span><span class="n">cout</span> <span class="o">&lt;&lt;</span> <span class="s">&quot;average of 3.0 and 4.0: &quot;</span> <span class="o">&lt;&lt;</span> <span class="n">average</span><span class="p">(</span><span class="mf">3.0</span><span class="p">,</span> <span class="mf">4.0</span><span class="p">)</span> <span class="o">&lt;&lt;</span> <span class="n">std</span><span class="o">::</span><span class="n">endl</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
</div>
<p>We link our program to output.o and check the result is what we
expected:</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>$ clang++ main.cpp output.o -o main
$ ./main
average of 3.0 and 4.0: 3.5
</pre></div>
</div>
</div>
<div class="section" id="full-code-listing">
<h2><a class="toc-backref" href="#id7"><span class="section-number">8.7. </span>Full Code Listing</a><a class="headerlink" href="#full-code-listing" title="Permalink to this headline">¶</a></h2>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span> <span class="cpf">&quot;llvm/ADT/APFloat.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ADT/Optional.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ADT/STLExtras.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/IR/BasicBlock.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/IR/Constants.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/IR/DerivedTypes.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/IR/Function.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/IR/Instructions.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/IR/IRBuilder.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/IR/LLVMContext.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/IR/LegacyPassManager.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/IR/Module.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/IR/Type.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/IR/Verifier.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/Support/FileSystem.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/Support/Host.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/Support/raw_ostream.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/Support/TargetRegistry.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/Support/TargetSelect.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/Target/TargetMachine.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/Target/TargetOptions.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&lt;algorithm&gt;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&lt;cassert&gt;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&lt;cctype&gt;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&lt;cstdio&gt;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&lt;cstdlib&gt;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&lt;map&gt;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&lt;memory&gt;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&lt;string&gt;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&lt;system_error&gt;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&lt;utility&gt;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&lt;vector&gt;</span><span class="cp"></span>

<span class="k">using</span> <span class="k">namespace</span> <span class="n">llvm</span><span class="p">;</span>
<span class="k">using</span> <span class="k">namespace</span> <span class="n">llvm</span><span class="o">::</span><span class="n">sys</span><span class="p">;</span>

<span class="c1">//===----------------------------------------------------------------------===//</span>
<span class="c1">// Lexer</span>
<span class="c1">//===----------------------------------------------------------------------===//</span>

<span class="c1">// The lexer returns tokens [0-255] if it is an unknown character, otherwise one</span>
<span class="c1">// of these for known things.</span>
<span class="k">enum</span> <span class="nc">Token</span> <span class="p">{</span>
  <span class="n">tok_eof</span> <span class="o">=</span> <span class="mi">-1</span><span class="p">,</span>

  <span class="c1">// commands</span>
  <span class="n">tok_def</span> <span class="o">=</span> <span class="mi">-2</span><span class="p">,</span>
  <span class="n">tok_extern</span> <span class="o">=</span> <span class="mi">-3</span><span class="p">,</span>

  <span class="c1">// primary</span>
  <span class="n">tok_identifier</span> <span class="o">=</span> <span class="mi">-4</span><span class="p">,</span>
  <span class="n">tok_number</span> <span class="o">=</span> <span class="mi">-5</span><span class="p">,</span>

  <span class="c1">// control</span>
  <span class="n">tok_if</span> <span class="o">=</span> <span class="mi">-6</span><span class="p">,</span>
  <span class="n">tok_then</span> <span class="o">=</span> <span class="mi">-7</span><span class="p">,</span>
  <span class="n">tok_else</span> <span class="o">=</span> <span class="mi">-8</span><span class="p">,</span>
  <span class="n">tok_for</span> <span class="o">=</span> <span class="mi">-9</span><span class="p">,</span>
  <span class="n">tok_in</span> <span class="o">=</span> <span class="mi">-10</span><span class="p">,</span>

  <span class="c1">// operators</span>
  <span class="n">tok_binary</span> <span class="o">=</span> <span class="mi">-11</span><span class="p">,</span>
  <span class="n">tok_unary</span> <span class="o">=</span> <span class="mi">-12</span><span class="p">,</span>

  <span class="c1">// var definition</span>
  <span class="n">tok_var</span> <span class="o">=</span> <span class="mi">-13</span>
<span class="p">};</span>

<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">IdentifierStr</span><span class="p">;</span> <span class="c1">// Filled in if tok_identifier</span>
<span class="k">static</span> <span class="kt">double</span> <span class="n">NumVal</span><span class="p">;</span>             <span class="c1">// Filled in if tok_number</span>

<span class="c1">/// gettok - Return the next token from standard input.</span>
<span class="k">static</span> <span class="kt">int</span> <span class="n">gettok</span><span class="p">()</span> <span class="p">{</span>
  <span class="k">static</span> <span class="kt">int</span> <span class="n">LastChar</span> <span class="o">=</span> <span class="sc">&#39; &#39;</span><span class="p">;</span>

  <span class="c1">// Skip any whitespace.</span>
  <span class="k">while</span> <span class="p">(</span><span class="n">isspace</span><span class="p">(</span><span class="n">LastChar</span><span class="p">))</span>
    <span class="n">LastChar</span> <span class="o">=</span> <span class="n">getchar</span><span class="p">();</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">isalpha</span><span class="p">(</span><span class="n">LastChar</span><span class="p">))</span> <span class="p">{</span> <span class="c1">// identifier: [a-zA-Z][a-zA-Z0-9]*</span>
    <span class="n">IdentifierStr</span> <span class="o">=</span> <span class="n">LastChar</span><span class="p">;</span>
    <span class="k">while</span> <span class="p">(</span><span class="n">isalnum</span><span class="p">((</span><span class="n">LastChar</span> <span class="o">=</span> <span class="n">getchar</span><span class="p">())))</span>
      <span class="n">IdentifierStr</span> <span class="o">+=</span> <span class="n">LastChar</span><span class="p">;</span>

    <span class="k">if</span> <span class="p">(</span><span class="n">IdentifierStr</span> <span class="o">==</span> <span class="s">&quot;def&quot;</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">tok_def</span><span class="p">;</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">IdentifierStr</span> <span class="o">==</span> <span class="s">&quot;extern&quot;</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">tok_extern</span><span class="p">;</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">IdentifierStr</span> <span class="o">==</span> <span class="s">&quot;if&quot;</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">tok_if</span><span class="p">;</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">IdentifierStr</span> <span class="o">==</span> <span class="s">&quot;then&quot;</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">tok_then</span><span class="p">;</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">IdentifierStr</span> <span class="o">==</span> <span class="s">&quot;else&quot;</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">tok_else</span><span class="p">;</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">IdentifierStr</span> <span class="o">==</span> <span class="s">&quot;for&quot;</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">tok_for</span><span class="p">;</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">IdentifierStr</span> <span class="o">==</span> <span class="s">&quot;in&quot;</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">tok_in</span><span class="p">;</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">IdentifierStr</span> <span class="o">==</span> <span class="s">&quot;binary&quot;</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">tok_binary</span><span class="p">;</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">IdentifierStr</span> <span class="o">==</span> <span class="s">&quot;unary&quot;</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">tok_unary</span><span class="p">;</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">IdentifierStr</span> <span class="o">==</span> <span class="s">&quot;var&quot;</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">tok_var</span><span class="p">;</span>
    <span class="k">return</span> <span class="n">tok_identifier</span><span class="p">;</span>
  <span class="p">}</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">isdigit</span><span class="p">(</span><span class="n">LastChar</span><span class="p">)</span> <span class="o">||</span> <span class="n">LastChar</span> <span class="o">==</span> <span class="sc">&#39;.&#39;</span><span class="p">)</span> <span class="p">{</span> <span class="c1">// Number: [0-9.]+</span>
    <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">NumStr</span><span class="p">;</span>
    <span class="k">do</span> <span class="p">{</span>
      <span class="n">NumStr</span> <span class="o">+=</span> <span class="n">LastChar</span><span class="p">;</span>
      <span class="n">LastChar</span> <span class="o">=</span> <span class="n">getchar</span><span class="p">();</span>
    <span class="p">}</span> <span class="k">while</span> <span class="p">(</span><span class="n">isdigit</span><span class="p">(</span><span class="n">LastChar</span><span class="p">)</span> <span class="o">||</span> <span class="n">LastChar</span> <span class="o">==</span> <span class="sc">&#39;.&#39;</span><span class="p">);</span>

    <span class="n">NumVal</span> <span class="o">=</span> <span class="n">strtod</span><span class="p">(</span><span class="n">NumStr</span><span class="p">.</span><span class="n">c_str</span><span class="p">(),</span> <span class="k">nullptr</span><span class="p">);</span>
    <span class="k">return</span> <span class="n">tok_number</span><span class="p">;</span>
  <span class="p">}</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">LastChar</span> <span class="o">==</span> <span class="sc">&#39;#&#39;</span><span class="p">)</span> <span class="p">{</span>
    <span class="c1">// Comment until end of line.</span>
    <span class="k">do</span>
      <span class="n">LastChar</span> <span class="o">=</span> <span class="n">getchar</span><span class="p">();</span>
    <span class="k">while</span> <span class="p">(</span><span class="n">LastChar</span> <span class="o">!=</span> <span class="n">EOF</span> <span class="o">&amp;&amp;</span> <span class="n">LastChar</span> <span class="o">!=</span> <span class="sc">&#39;\n&#39;</span> <span class="o">&amp;&amp;</span> <span class="n">LastChar</span> <span class="o">!=</span> <span class="sc">&#39;\r&#39;</span><span class="p">);</span>

    <span class="k">if</span> <span class="p">(</span><span class="n">LastChar</span> <span class="o">!=</span> <span class="n">EOF</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">gettok</span><span class="p">();</span>
  <span class="p">}</span>

  <span class="c1">// Check for end of file.  Don&#39;t eat the EOF.</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">LastChar</span> <span class="o">==</span> <span class="n">EOF</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">tok_eof</span><span class="p">;</span>

  <span class="c1">// Otherwise, just return the character as its ascii value.</span>
  <span class="kt">int</span> <span class="n">ThisChar</span> <span class="o">=</span> <span class="n">LastChar</span><span class="p">;</span>
  <span class="n">LastChar</span> <span class="o">=</span> <span class="n">getchar</span><span class="p">();</span>
  <span class="k">return</span> <span class="n">ThisChar</span><span class="p">;</span>
<span class="p">}</span>

<span class="c1">//===----------------------------------------------------------------------===//</span>
<span class="c1">// Abstract Syntax Tree (aka Parse Tree)</span>
<span class="c1">//===----------------------------------------------------------------------===//</span>

<span class="k">namespace</span> <span class="p">{</span>

<span class="c1">/// ExprAST - Base class for all expression nodes.</span>
<span class="k">class</span> <span class="nc">ExprAST</span> <span class="p">{</span>
<span class="k">public</span><span class="o">:</span>
  <span class="k">virtual</span> <span class="o">~</span><span class="n">ExprAST</span><span class="p">()</span> <span class="o">=</span> <span class="k">default</span><span class="p">;</span>

  <span class="k">virtual</span> <span class="n">Value</span> <span class="o">*</span><span class="n">codegen</span><span class="p">()</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">};</span>

<span class="c1">/// NumberExprAST - Expression class for numeric literals like &quot;1.0&quot;.</span>
<span class="k">class</span> <span class="nc">NumberExprAST</span> <span class="o">:</span> <span class="k">public</span> <span class="n">ExprAST</span> <span class="p">{</span>
  <span class="kt">double</span> <span class="n">Val</span><span class="p">;</span>

<span class="k">public</span><span class="o">:</span>
  <span class="n">NumberExprAST</span><span class="p">(</span><span class="kt">double</span> <span class="n">Val</span><span class="p">)</span> <span class="o">:</span> <span class="n">Val</span><span class="p">(</span><span class="n">Val</span><span class="p">)</span> <span class="p">{}</span>

  <span class="n">Value</span> <span class="o">*</span><span class="n">codegen</span><span class="p">()</span> <span class="k">override</span><span class="p">;</span>
<span class="p">};</span>

<span class="c1">/// VariableExprAST - Expression class for referencing a variable, like &quot;a&quot;.</span>
<span class="k">class</span> <span class="nc">VariableExprAST</span> <span class="o">:</span> <span class="k">public</span> <span class="n">ExprAST</span> <span class="p">{</span>
  <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">Name</span><span class="p">;</span>

<span class="k">public</span><span class="o">:</span>
  <span class="n">VariableExprAST</span><span class="p">(</span><span class="k">const</span> <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="o">&amp;</span><span class="n">Name</span><span class="p">)</span> <span class="o">:</span> <span class="n">Name</span><span class="p">(</span><span class="n">Name</span><span class="p">)</span> <span class="p">{}</span>

  <span class="n">Value</span> <span class="o">*</span><span class="n">codegen</span><span class="p">()</span> <span class="k">override</span><span class="p">;</span>
  <span class="k">const</span> <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="o">&amp;</span><span class="n">getName</span><span class="p">()</span> <span class="k">const</span> <span class="p">{</span> <span class="k">return</span> <span class="n">Name</span><span class="p">;</span> <span class="p">}</span>
<span class="p">};</span>

<span class="c1">/// UnaryExprAST - Expression class for a unary operator.</span>
<span class="k">class</span> <span class="nc">UnaryExprAST</span> <span class="o">:</span> <span class="k">public</span> <span class="n">ExprAST</span> <span class="p">{</span>
  <span class="kt">char</span> <span class="n">Opcode</span><span class="p">;</span>
  <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Operand</span><span class="p">;</span>

<span class="k">public</span><span class="o">:</span>
  <span class="n">UnaryExprAST</span><span class="p">(</span><span class="kt">char</span> <span class="n">Opcode</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Operand</span><span class="p">)</span>
      <span class="o">:</span> <span class="n">Opcode</span><span class="p">(</span><span class="n">Opcode</span><span class="p">),</span> <span class="n">Operand</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Operand</span><span class="p">))</span> <span class="p">{}</span>

  <span class="n">Value</span> <span class="o">*</span><span class="n">codegen</span><span class="p">()</span> <span class="k">override</span><span class="p">;</span>
<span class="p">};</span>

<span class="c1">/// BinaryExprAST - Expression class for a binary operator.</span>
<span class="k">class</span> <span class="nc">BinaryExprAST</span> <span class="o">:</span> <span class="k">public</span> <span class="n">ExprAST</span> <span class="p">{</span>
  <span class="kt">char</span> <span class="n">Op</span><span class="p">;</span>
  <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">LHS</span><span class="p">,</span> <span class="n">RHS</span><span class="p">;</span>

<span class="k">public</span><span class="o">:</span>
  <span class="n">BinaryExprAST</span><span class="p">(</span><span class="kt">char</span> <span class="n">Op</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">LHS</span><span class="p">,</span>
                <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">RHS</span><span class="p">)</span>
      <span class="o">:</span> <span class="n">Op</span><span class="p">(</span><span class="n">Op</span><span class="p">),</span> <span class="n">LHS</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">LHS</span><span class="p">)),</span> <span class="n">RHS</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">RHS</span><span class="p">))</span> <span class="p">{}</span>

  <span class="n">Value</span> <span class="o">*</span><span class="n">codegen</span><span class="p">()</span> <span class="k">override</span><span class="p">;</span>
<span class="p">};</span>

<span class="c1">/// CallExprAST - Expression class for function calls.</span>
<span class="k">class</span> <span class="nc">CallExprAST</span> <span class="o">:</span> <span class="k">public</span> <span class="n">ExprAST</span> <span class="p">{</span>
  <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">Callee</span><span class="p">;</span>
  <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;&gt;</span> <span class="n">Args</span><span class="p">;</span>

<span class="k">public</span><span class="o">:</span>
  <span class="n">CallExprAST</span><span class="p">(</span><span class="k">const</span> <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="o">&amp;</span><span class="n">Callee</span><span class="p">,</span>
              <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;&gt;</span> <span class="n">Args</span><span class="p">)</span>
      <span class="o">:</span> <span class="n">Callee</span><span class="p">(</span><span class="n">Callee</span><span class="p">),</span> <span class="n">Args</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Args</span><span class="p">))</span> <span class="p">{}</span>

  <span class="n">Value</span> <span class="o">*</span><span class="n">codegen</span><span class="p">()</span> <span class="k">override</span><span class="p">;</span>
<span class="p">};</span>

<span class="c1">/// IfExprAST - Expression class for if/then/else.</span>
<span class="k">class</span> <span class="nc">IfExprAST</span> <span class="o">:</span> <span class="k">public</span> <span class="n">ExprAST</span> <span class="p">{</span>
  <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Cond</span><span class="p">,</span> <span class="n">Then</span><span class="p">,</span> <span class="n">Else</span><span class="p">;</span>

<span class="k">public</span><span class="o">:</span>
  <span class="n">IfExprAST</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Cond</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Then</span><span class="p">,</span>
            <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Else</span><span class="p">)</span>
      <span class="o">:</span> <span class="n">Cond</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Cond</span><span class="p">)),</span> <span class="n">Then</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Then</span><span class="p">)),</span> <span class="n">Else</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Else</span><span class="p">))</span> <span class="p">{}</span>

  <span class="n">Value</span> <span class="o">*</span><span class="n">codegen</span><span class="p">()</span> <span class="k">override</span><span class="p">;</span>
<span class="p">};</span>

<span class="c1">/// ForExprAST - Expression class for for/in.</span>
<span class="k">class</span> <span class="nc">ForExprAST</span> <span class="o">:</span> <span class="k">public</span> <span class="n">ExprAST</span> <span class="p">{</span>
  <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">VarName</span><span class="p">;</span>
  <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Start</span><span class="p">,</span> <span class="n">End</span><span class="p">,</span> <span class="n">Step</span><span class="p">,</span> <span class="n">Body</span><span class="p">;</span>

<span class="k">public</span><span class="o">:</span>
  <span class="n">ForExprAST</span><span class="p">(</span><span class="k">const</span> <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="o">&amp;</span><span class="n">VarName</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Start</span><span class="p">,</span>
             <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">End</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Step</span><span class="p">,</span>
             <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Body</span><span class="p">)</span>
      <span class="o">:</span> <span class="n">VarName</span><span class="p">(</span><span class="n">VarName</span><span class="p">),</span> <span class="n">Start</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Start</span><span class="p">)),</span> <span class="n">End</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">End</span><span class="p">)),</span>
        <span class="n">Step</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Step</span><span class="p">)),</span> <span class="n">Body</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Body</span><span class="p">))</span> <span class="p">{}</span>

  <span class="n">Value</span> <span class="o">*</span><span class="n">codegen</span><span class="p">()</span> <span class="k">override</span><span class="p">;</span>
<span class="p">};</span>

<span class="c1">/// VarExprAST - Expression class for var/in</span>
<span class="k">class</span> <span class="nc">VarExprAST</span> <span class="o">:</span> <span class="k">public</span> <span class="n">ExprAST</span> <span class="p">{</span>
  <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">pair</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;&gt;&gt;</span> <span class="n">VarNames</span><span class="p">;</span>
  <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Body</span><span class="p">;</span>

<span class="k">public</span><span class="o">:</span>
  <span class="n">VarExprAST</span><span class="p">(</span>
      <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">pair</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;&gt;&gt;</span> <span class="n">VarNames</span><span class="p">,</span>
      <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Body</span><span class="p">)</span>
      <span class="o">:</span> <span class="n">VarNames</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">VarNames</span><span class="p">)),</span> <span class="n">Body</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Body</span><span class="p">))</span> <span class="p">{}</span>

  <span class="n">Value</span> <span class="o">*</span><span class="n">codegen</span><span class="p">()</span> <span class="k">override</span><span class="p">;</span>
<span class="p">};</span>

<span class="c1">/// PrototypeAST - This class represents the &quot;prototype&quot; for a function,</span>
<span class="c1">/// which captures its name, and its argument names (thus implicitly the number</span>
<span class="c1">/// of arguments the function takes), as well as if it is an operator.</span>
<span class="k">class</span> <span class="nc">PrototypeAST</span> <span class="p">{</span>
  <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">Name</span><span class="p">;</span>
  <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">&gt;</span> <span class="n">Args</span><span class="p">;</span>
  <span class="kt">bool</span> <span class="n">IsOperator</span><span class="p">;</span>
  <span class="kt">unsigned</span> <span class="n">Precedence</span><span class="p">;</span> <span class="c1">// Precedence if a binary op.</span>

<span class="k">public</span><span class="o">:</span>
  <span class="n">PrototypeAST</span><span class="p">(</span><span class="k">const</span> <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="o">&amp;</span><span class="n">Name</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">&gt;</span> <span class="n">Args</span><span class="p">,</span>
               <span class="kt">bool</span> <span class="n">IsOperator</span> <span class="o">=</span> <span class="nb">false</span><span class="p">,</span> <span class="kt">unsigned</span> <span class="n">Prec</span> <span class="o">=</span> <span class="mi">0</span><span class="p">)</span>
      <span class="o">:</span> <span class="n">Name</span><span class="p">(</span><span class="n">Name</span><span class="p">),</span> <span class="n">Args</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Args</span><span class="p">)),</span> <span class="n">IsOperator</span><span class="p">(</span><span class="n">IsOperator</span><span class="p">),</span>
        <span class="n">Precedence</span><span class="p">(</span><span class="n">Prec</span><span class="p">)</span> <span class="p">{}</span>

  <span class="n">Function</span> <span class="o">*</span><span class="n">codegen</span><span class="p">();</span>
  <span class="k">const</span> <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="o">&amp;</span><span class="n">getName</span><span class="p">()</span> <span class="k">const</span> <span class="p">{</span> <span class="k">return</span> <span class="n">Name</span><span class="p">;</span> <span class="p">}</span>

  <span class="kt">bool</span> <span class="n">isUnaryOp</span><span class="p">()</span> <span class="k">const</span> <span class="p">{</span> <span class="k">return</span> <span class="n">IsOperator</span> <span class="o">&amp;&amp;</span> <span class="n">Args</span><span class="p">.</span><span class="n">size</span><span class="p">()</span> <span class="o">==</span> <span class="mi">1</span><span class="p">;</span> <span class="p">}</span>
  <span class="kt">bool</span> <span class="n">isBinaryOp</span><span class="p">()</span> <span class="k">const</span> <span class="p">{</span> <span class="k">return</span> <span class="n">IsOperator</span> <span class="o">&amp;&amp;</span> <span class="n">Args</span><span class="p">.</span><span class="n">size</span><span class="p">()</span> <span class="o">==</span> <span class="mi">2</span><span class="p">;</span> <span class="p">}</span>

  <span class="kt">char</span> <span class="n">getOperatorName</span><span class="p">()</span> <span class="k">const</span> <span class="p">{</span>
    <span class="n">assert</span><span class="p">(</span><span class="n">isUnaryOp</span><span class="p">()</span> <span class="o">||</span> <span class="n">isBinaryOp</span><span class="p">());</span>
    <span class="k">return</span> <span class="n">Name</span><span class="p">[</span><span class="n">Name</span><span class="p">.</span><span class="n">size</span><span class="p">()</span> <span class="o">-</span> <span class="mi">1</span><span class="p">];</span>
  <span class="p">}</span>

  <span class="kt">unsigned</span> <span class="n">getBinaryPrecedence</span><span class="p">()</span> <span class="k">const</span> <span class="p">{</span> <span class="k">return</span> <span class="n">Precedence</span><span class="p">;</span> <span class="p">}</span>
<span class="p">};</span>

<span class="c1">/// FunctionAST - This class represents a function definition itself.</span>
<span class="k">class</span> <span class="nc">FunctionAST</span> <span class="p">{</span>
  <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">PrototypeAST</span><span class="o">&gt;</span> <span class="n">Proto</span><span class="p">;</span>
  <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Body</span><span class="p">;</span>

<span class="k">public</span><span class="o">:</span>
  <span class="n">FunctionAST</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">PrototypeAST</span><span class="o">&gt;</span> <span class="n">Proto</span><span class="p">,</span>
              <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Body</span><span class="p">)</span>
      <span class="o">:</span> <span class="n">Proto</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Proto</span><span class="p">)),</span> <span class="n">Body</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Body</span><span class="p">))</span> <span class="p">{}</span>

  <span class="n">Function</span> <span class="o">*</span><span class="n">codegen</span><span class="p">();</span>
<span class="p">};</span>

<span class="p">}</span> <span class="c1">// end anonymous namespace</span>

<span class="c1">//===----------------------------------------------------------------------===//</span>
<span class="c1">// Parser</span>
<span class="c1">//===----------------------------------------------------------------------===//</span>

<span class="c1">/// CurTok/getNextToken - Provide a simple token buffer.  CurTok is the current</span>
<span class="c1">/// token the parser is looking at.  getNextToken reads another token from the</span>
<span class="c1">/// lexer and updates CurTok with its results.</span>
<span class="k">static</span> <span class="kt">int</span> <span class="n">CurTok</span><span class="p">;</span>
<span class="k">static</span> <span class="kt">int</span> <span class="n">getNextToken</span><span class="p">()</span> <span class="p">{</span> <span class="k">return</span> <span class="n">CurTok</span> <span class="o">=</span> <span class="n">gettok</span><span class="p">();</span> <span class="p">}</span>

<span class="c1">/// BinopPrecedence - This holds the precedence for each binary operator that is</span>
<span class="c1">/// defined.</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">map</span><span class="o">&lt;</span><span class="kt">char</span><span class="p">,</span> <span class="kt">int</span><span class="o">&gt;</span> <span class="n">BinopPrecedence</span><span class="p">;</span>

<span class="c1">/// GetTokPrecedence - Get the precedence of the pending binary operator token.</span>
<span class="k">static</span> <span class="kt">int</span> <span class="n">GetTokPrecedence</span><span class="p">()</span> <span class="p">{</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">isascii</span><span class="p">(</span><span class="n">CurTok</span><span class="p">))</span>
    <span class="k">return</span> <span class="mi">-1</span><span class="p">;</span>

  <span class="c1">// Make sure it&#39;s a declared binop.</span>
  <span class="kt">int</span> <span class="n">TokPrec</span> <span class="o">=</span> <span class="n">BinopPrecedence</span><span class="p">[</span><span class="n">CurTok</span><span class="p">];</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">TokPrec</span> <span class="o">&lt;=</span> <span class="mi">0</span><span class="p">)</span>
    <span class="k">return</span> <span class="mi">-1</span><span class="p">;</span>
  <span class="k">return</span> <span class="n">TokPrec</span><span class="p">;</span>
<span class="p">}</span>

<span class="c1">/// LogError* - These are little helper functions for error handling.</span>
<span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">LogError</span><span class="p">(</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">Str</span><span class="p">)</span> <span class="p">{</span>
  <span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;Error: %s</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">,</span> <span class="n">Str</span><span class="p">);</span>
  <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
<span class="p">}</span>

<span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">PrototypeAST</span><span class="o">&gt;</span> <span class="n">LogErrorP</span><span class="p">(</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">Str</span><span class="p">)</span> <span class="p">{</span>
  <span class="n">LogError</span><span class="p">(</span><span class="n">Str</span><span class="p">);</span>
  <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
<span class="p">}</span>

<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">ParseExpression</span><span class="p">();</span>

<span class="c1">/// numberexpr ::= number</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">ParseNumberExpr</span><span class="p">()</span> <span class="p">{</span>
  <span class="k">auto</span> <span class="n">Result</span> <span class="o">=</span> <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">NumberExprAST</span><span class="o">&gt;</span><span class="p">(</span><span class="n">NumVal</span><span class="p">);</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// consume the number</span>
  <span class="k">return</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Result</span><span class="p">);</span>
<span class="p">}</span>

<span class="c1">/// parenexpr ::= &#39;(&#39; expression &#39;)&#39;</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">ParseParenExpr</span><span class="p">()</span> <span class="p">{</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat (.</span>
  <span class="k">auto</span> <span class="n">V</span> <span class="o">=</span> <span class="n">ParseExpression</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">V</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="sc">&#39;)&#39;</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogError</span><span class="p">(</span><span class="s">&quot;expected &#39;)&#39;&quot;</span><span class="p">);</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat ).</span>
  <span class="k">return</span> <span class="n">V</span><span class="p">;</span>
<span class="p">}</span>

<span class="c1">/// identifierexpr</span>
<span class="c1">///   ::= identifier</span>
<span class="c1">///   ::= identifier &#39;(&#39; expression* &#39;)&#39;</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">ParseIdentifierExpr</span><span class="p">()</span> <span class="p">{</span>
  <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">IdName</span> <span class="o">=</span> <span class="n">IdentifierStr</span><span class="p">;</span>

  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat identifier.</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="sc">&#39;(&#39;</span><span class="p">)</span> <span class="c1">// Simple variable ref.</span>
    <span class="k">return</span> <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">VariableExprAST</span><span class="o">&gt;</span><span class="p">(</span><span class="n">IdName</span><span class="p">);</span>

  <span class="c1">// Call.</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat (</span>
  <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;&gt;</span> <span class="n">Args</span><span class="p">;</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="sc">&#39;)&#39;</span><span class="p">)</span> <span class="p">{</span>
    <span class="k">while</span> <span class="p">(</span><span class="nb">true</span><span class="p">)</span> <span class="p">{</span>
      <span class="k">if</span> <span class="p">(</span><span class="k">auto</span> <span class="n">Arg</span> <span class="o">=</span> <span class="n">ParseExpression</span><span class="p">())</span>
        <span class="n">Args</span><span class="p">.</span><span class="n">push_back</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Arg</span><span class="p">));</span>
      <span class="k">else</span>
        <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

      <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">==</span> <span class="sc">&#39;)&#39;</span><span class="p">)</span>
        <span class="k">break</span><span class="p">;</span>

      <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="sc">&#39;,&#39;</span><span class="p">)</span>
        <span class="k">return</span> <span class="n">LogError</span><span class="p">(</span><span class="s">&quot;Expected &#39;)&#39; or &#39;,&#39; in argument list&quot;</span><span class="p">);</span>
      <span class="n">getNextToken</span><span class="p">();</span>
    <span class="p">}</span>
  <span class="p">}</span>

  <span class="c1">// Eat the &#39;)&#39;.</span>
  <span class="n">getNextToken</span><span class="p">();</span>

  <span class="k">return</span> <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">CallExprAST</span><span class="o">&gt;</span><span class="p">(</span><span class="n">IdName</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Args</span><span class="p">));</span>
<span class="p">}</span>

<span class="c1">/// ifexpr ::= &#39;if&#39; expression &#39;then&#39; expression &#39;else&#39; expression</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">ParseIfExpr</span><span class="p">()</span> <span class="p">{</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat the if.</span>

  <span class="c1">// condition.</span>
  <span class="k">auto</span> <span class="n">Cond</span> <span class="o">=</span> <span class="n">ParseExpression</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">Cond</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="n">tok_then</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogError</span><span class="p">(</span><span class="s">&quot;expected then&quot;</span><span class="p">);</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat the then</span>

  <span class="k">auto</span> <span class="n">Then</span> <span class="o">=</span> <span class="n">ParseExpression</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">Then</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="n">tok_else</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogError</span><span class="p">(</span><span class="s">&quot;expected else&quot;</span><span class="p">);</span>

  <span class="n">getNextToken</span><span class="p">();</span>

  <span class="k">auto</span> <span class="n">Else</span> <span class="o">=</span> <span class="n">ParseExpression</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">Else</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="k">return</span> <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">IfExprAST</span><span class="o">&gt;</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Cond</span><span class="p">),</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Then</span><span class="p">),</span>
                                      <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Else</span><span class="p">));</span>
<span class="p">}</span>

<span class="c1">/// forexpr ::= &#39;for&#39; identifier &#39;=&#39; expr &#39;,&#39; expr (&#39;,&#39; expr)? &#39;in&#39; expression</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">ParseForExpr</span><span class="p">()</span> <span class="p">{</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat the for.</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="n">tok_identifier</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogError</span><span class="p">(</span><span class="s">&quot;expected identifier after for&quot;</span><span class="p">);</span>

  <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">IdName</span> <span class="o">=</span> <span class="n">IdentifierStr</span><span class="p">;</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat identifier.</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="sc">&#39;=&#39;</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogError</span><span class="p">(</span><span class="s">&quot;expected &#39;=&#39; after for&quot;</span><span class="p">);</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat &#39;=&#39;.</span>

  <span class="k">auto</span> <span class="n">Start</span> <span class="o">=</span> <span class="n">ParseExpression</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">Start</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="sc">&#39;,&#39;</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogError</span><span class="p">(</span><span class="s">&quot;expected &#39;,&#39; after for start value&quot;</span><span class="p">);</span>
  <span class="n">getNextToken</span><span class="p">();</span>

  <span class="k">auto</span> <span class="n">End</span> <span class="o">=</span> <span class="n">ParseExpression</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">End</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="c1">// The step value is optional.</span>
  <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Step</span><span class="p">;</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">==</span> <span class="sc">&#39;,&#39;</span><span class="p">)</span> <span class="p">{</span>
    <span class="n">getNextToken</span><span class="p">();</span>
    <span class="n">Step</span> <span class="o">=</span> <span class="n">ParseExpression</span><span class="p">();</span>
    <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">Step</span><span class="p">)</span>
      <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
  <span class="p">}</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="n">tok_in</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogError</span><span class="p">(</span><span class="s">&quot;expected &#39;in&#39; after for&quot;</span><span class="p">);</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat &#39;in&#39;.</span>

  <span class="k">auto</span> <span class="n">Body</span> <span class="o">=</span> <span class="n">ParseExpression</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">Body</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="k">return</span> <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">ForExprAST</span><span class="o">&gt;</span><span class="p">(</span><span class="n">IdName</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Start</span><span class="p">),</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">End</span><span class="p">),</span>
                                       <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Step</span><span class="p">),</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Body</span><span class="p">));</span>
<span class="p">}</span>

<span class="c1">/// varexpr ::= &#39;var&#39; identifier (&#39;=&#39; expression)?</span>
<span class="c1">//                    (&#39;,&#39; identifier (&#39;=&#39; expression)?)* &#39;in&#39; expression</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">ParseVarExpr</span><span class="p">()</span> <span class="p">{</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat the var.</span>

  <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">pair</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;&gt;&gt;</span> <span class="n">VarNames</span><span class="p">;</span>

  <span class="c1">// At least one variable name is required.</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="n">tok_identifier</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogError</span><span class="p">(</span><span class="s">&quot;expected identifier after var&quot;</span><span class="p">);</span>

  <span class="k">while</span> <span class="p">(</span><span class="nb">true</span><span class="p">)</span> <span class="p">{</span>
    <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">Name</span> <span class="o">=</span> <span class="n">IdentifierStr</span><span class="p">;</span>
    <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat identifier.</span>

    <span class="c1">// Read the optional initializer.</span>
    <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">Init</span> <span class="o">=</span> <span class="k">nullptr</span><span class="p">;</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">==</span> <span class="sc">&#39;=&#39;</span><span class="p">)</span> <span class="p">{</span>
      <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat the &#39;=&#39;.</span>

      <span class="n">Init</span> <span class="o">=</span> <span class="n">ParseExpression</span><span class="p">();</span>
      <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">Init</span><span class="p">)</span>
        <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
    <span class="p">}</span>

    <span class="n">VarNames</span><span class="p">.</span><span class="n">push_back</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">make_pair</span><span class="p">(</span><span class="n">Name</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Init</span><span class="p">)));</span>

    <span class="c1">// End of var list, exit loop.</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="sc">&#39;,&#39;</span><span class="p">)</span>
      <span class="k">break</span><span class="p">;</span>
    <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat the &#39;,&#39;.</span>

    <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="n">tok_identifier</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">LogError</span><span class="p">(</span><span class="s">&quot;expected identifier list after var&quot;</span><span class="p">);</span>
  <span class="p">}</span>

  <span class="c1">// At this point, we have to have &#39;in&#39;.</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="n">tok_in</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogError</span><span class="p">(</span><span class="s">&quot;expected &#39;in&#39; keyword after &#39;var&#39;&quot;</span><span class="p">);</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat &#39;in&#39;.</span>

  <span class="k">auto</span> <span class="n">Body</span> <span class="o">=</span> <span class="n">ParseExpression</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">Body</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="k">return</span> <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">VarExprAST</span><span class="o">&gt;</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">VarNames</span><span class="p">),</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Body</span><span class="p">));</span>
<span class="p">}</span>

<span class="c1">/// primary</span>
<span class="c1">///   ::= identifierexpr</span>
<span class="c1">///   ::= numberexpr</span>
<span class="c1">///   ::= parenexpr</span>
<span class="c1">///   ::= ifexpr</span>
<span class="c1">///   ::= forexpr</span>
<span class="c1">///   ::= varexpr</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">ParsePrimary</span><span class="p">()</span> <span class="p">{</span>
  <span class="k">switch</span> <span class="p">(</span><span class="n">CurTok</span><span class="p">)</span> <span class="p">{</span>
  <span class="k">default</span><span class="o">:</span>
    <span class="k">return</span> <span class="n">LogError</span><span class="p">(</span><span class="s">&quot;unknown token when expecting an expression&quot;</span><span class="p">);</span>
  <span class="k">case</span> <span class="nl">tok_identifier</span><span class="p">:</span>
    <span class="k">return</span> <span class="n">ParseIdentifierExpr</span><span class="p">();</span>
  <span class="k">case</span> <span class="nl">tok_number</span><span class="p">:</span>
    <span class="k">return</span> <span class="n">ParseNumberExpr</span><span class="p">();</span>
  <span class="k">case</span> <span class="sc">&#39;(&#39;</span><span class="o">:</span>
    <span class="k">return</span> <span class="n">ParseParenExpr</span><span class="p">();</span>
  <span class="k">case</span> <span class="nl">tok_if</span><span class="p">:</span>
    <span class="k">return</span> <span class="n">ParseIfExpr</span><span class="p">();</span>
  <span class="k">case</span> <span class="nl">tok_for</span><span class="p">:</span>
    <span class="k">return</span> <span class="n">ParseForExpr</span><span class="p">();</span>
  <span class="k">case</span> <span class="nl">tok_var</span><span class="p">:</span>
    <span class="k">return</span> <span class="n">ParseVarExpr</span><span class="p">();</span>
  <span class="p">}</span>
<span class="p">}</span>

<span class="c1">/// unary</span>
<span class="c1">///   ::= primary</span>
<span class="c1">///   ::= &#39;!&#39; unary</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">ParseUnary</span><span class="p">()</span> <span class="p">{</span>
  <span class="c1">// If the current token is not an operator, it must be a primary expr.</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">isascii</span><span class="p">(</span><span class="n">CurTok</span><span class="p">)</span> <span class="o">||</span> <span class="n">CurTok</span> <span class="o">==</span> <span class="sc">&#39;(&#39;</span> <span class="o">||</span> <span class="n">CurTok</span> <span class="o">==</span> <span class="sc">&#39;,&#39;</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">ParsePrimary</span><span class="p">();</span>

  <span class="c1">// If this is a unary operator, read it.</span>
  <span class="kt">int</span> <span class="n">Opc</span> <span class="o">=</span> <span class="n">CurTok</span><span class="p">;</span>
  <span class="n">getNextToken</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="k">auto</span> <span class="n">Operand</span> <span class="o">=</span> <span class="n">ParseUnary</span><span class="p">())</span>
    <span class="k">return</span> <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">UnaryExprAST</span><span class="o">&gt;</span><span class="p">(</span><span class="n">Opc</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Operand</span><span class="p">));</span>
  <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
<span class="p">}</span>

<span class="c1">/// binoprhs</span>
<span class="c1">///   ::= (&#39;+&#39; unary)*</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">ParseBinOpRHS</span><span class="p">(</span><span class="kt">int</span> <span class="n">ExprPrec</span><span class="p">,</span>
                                              <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">LHS</span><span class="p">)</span> <span class="p">{</span>
  <span class="c1">// If this is a binop, find its precedence.</span>
  <span class="k">while</span> <span class="p">(</span><span class="nb">true</span><span class="p">)</span> <span class="p">{</span>
    <span class="kt">int</span> <span class="n">TokPrec</span> <span class="o">=</span> <span class="n">GetTokPrecedence</span><span class="p">();</span>

    <span class="c1">// If this is a binop that binds at least as tightly as the current binop,</span>
    <span class="c1">// consume it, otherwise we are done.</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">TokPrec</span> <span class="o">&lt;</span> <span class="n">ExprPrec</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">LHS</span><span class="p">;</span>

    <span class="c1">// Okay, we know this is a binop.</span>
    <span class="kt">int</span> <span class="n">BinOp</span> <span class="o">=</span> <span class="n">CurTok</span><span class="p">;</span>
    <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat binop</span>

    <span class="c1">// Parse the unary expression after the binary operator.</span>
    <span class="k">auto</span> <span class="n">RHS</span> <span class="o">=</span> <span class="n">ParseUnary</span><span class="p">();</span>
    <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">RHS</span><span class="p">)</span>
      <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

    <span class="c1">// If BinOp binds less tightly with RHS than the operator after RHS, let</span>
    <span class="c1">// the pending operator take RHS as its LHS.</span>
    <span class="kt">int</span> <span class="n">NextPrec</span> <span class="o">=</span> <span class="n">GetTokPrecedence</span><span class="p">();</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">TokPrec</span> <span class="o">&lt;</span> <span class="n">NextPrec</span><span class="p">)</span> <span class="p">{</span>
      <span class="n">RHS</span> <span class="o">=</span> <span class="n">ParseBinOpRHS</span><span class="p">(</span><span class="n">TokPrec</span> <span class="o">+</span> <span class="mi">1</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">RHS</span><span class="p">));</span>
      <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">RHS</span><span class="p">)</span>
        <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
    <span class="p">}</span>

    <span class="c1">// Merge LHS/RHS.</span>
    <span class="n">LHS</span> <span class="o">=</span>
        <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">BinaryExprAST</span><span class="o">&gt;</span><span class="p">(</span><span class="n">BinOp</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">LHS</span><span class="p">),</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">RHS</span><span class="p">));</span>
  <span class="p">}</span>
<span class="p">}</span>

<span class="c1">/// expression</span>
<span class="c1">///   ::= unary binoprhs</span>
<span class="c1">///</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">ExprAST</span><span class="o">&gt;</span> <span class="n">ParseExpression</span><span class="p">()</span> <span class="p">{</span>
  <span class="k">auto</span> <span class="n">LHS</span> <span class="o">=</span> <span class="n">ParseUnary</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">LHS</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="k">return</span> <span class="nf">ParseBinOpRHS</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">LHS</span><span class="p">));</span>
<span class="p">}</span>

<span class="c1">/// prototype</span>
<span class="c1">///   ::= id &#39;(&#39; id* &#39;)&#39;</span>
<span class="c1">///   ::= binary LETTER number? (id, id)</span>
<span class="c1">///   ::= unary LETTER (id)</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">PrototypeAST</span><span class="o">&gt;</span> <span class="n">ParsePrototype</span><span class="p">()</span> <span class="p">{</span>
  <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">FnName</span><span class="p">;</span>

  <span class="kt">unsigned</span> <span class="n">Kind</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span> <span class="c1">// 0 = identifier, 1 = unary, 2 = binary.</span>
  <span class="kt">unsigned</span> <span class="n">BinaryPrecedence</span> <span class="o">=</span> <span class="mi">30</span><span class="p">;</span>

  <span class="k">switch</span> <span class="p">(</span><span class="n">CurTok</span><span class="p">)</span> <span class="p">{</span>
  <span class="k">default</span><span class="o">:</span>
    <span class="k">return</span> <span class="n">LogErrorP</span><span class="p">(</span><span class="s">&quot;Expected function name in prototype&quot;</span><span class="p">);</span>
  <span class="k">case</span> <span class="nl">tok_identifier</span><span class="p">:</span>
    <span class="n">FnName</span> <span class="o">=</span> <span class="n">IdentifierStr</span><span class="p">;</span>
    <span class="n">Kind</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
    <span class="n">getNextToken</span><span class="p">();</span>
    <span class="k">break</span><span class="p">;</span>
  <span class="k">case</span> <span class="nl">tok_unary</span><span class="p">:</span>
    <span class="n">getNextToken</span><span class="p">();</span>
    <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">isascii</span><span class="p">(</span><span class="n">CurTok</span><span class="p">))</span>
      <span class="k">return</span> <span class="n">LogErrorP</span><span class="p">(</span><span class="s">&quot;Expected unary operator&quot;</span><span class="p">);</span>
    <span class="n">FnName</span> <span class="o">=</span> <span class="s">&quot;unary&quot;</span><span class="p">;</span>
    <span class="n">FnName</span> <span class="o">+=</span> <span class="p">(</span><span class="kt">char</span><span class="p">)</span><span class="n">CurTok</span><span class="p">;</span>
    <span class="n">Kind</span> <span class="o">=</span> <span class="mi">1</span><span class="p">;</span>
    <span class="n">getNextToken</span><span class="p">();</span>
    <span class="k">break</span><span class="p">;</span>
  <span class="k">case</span> <span class="nl">tok_binary</span><span class="p">:</span>
    <span class="n">getNextToken</span><span class="p">();</span>
    <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">isascii</span><span class="p">(</span><span class="n">CurTok</span><span class="p">))</span>
      <span class="k">return</span> <span class="n">LogErrorP</span><span class="p">(</span><span class="s">&quot;Expected binary operator&quot;</span><span class="p">);</span>
    <span class="n">FnName</span> <span class="o">=</span> <span class="s">&quot;binary&quot;</span><span class="p">;</span>
    <span class="n">FnName</span> <span class="o">+=</span> <span class="p">(</span><span class="kt">char</span><span class="p">)</span><span class="n">CurTok</span><span class="p">;</span>
    <span class="n">Kind</span> <span class="o">=</span> <span class="mi">2</span><span class="p">;</span>
    <span class="n">getNextToken</span><span class="p">();</span>

    <span class="c1">// Read the precedence if present.</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">==</span> <span class="n">tok_number</span><span class="p">)</span> <span class="p">{</span>
      <span class="k">if</span> <span class="p">(</span><span class="n">NumVal</span> <span class="o">&lt;</span> <span class="mi">1</span> <span class="o">||</span> <span class="n">NumVal</span> <span class="o">&gt;</span> <span class="mi">100</span><span class="p">)</span>
        <span class="k">return</span> <span class="n">LogErrorP</span><span class="p">(</span><span class="s">&quot;Invalid precedence: must be 1..100&quot;</span><span class="p">);</span>
      <span class="n">BinaryPrecedence</span> <span class="o">=</span> <span class="p">(</span><span class="kt">unsigned</span><span class="p">)</span><span class="n">NumVal</span><span class="p">;</span>
      <span class="n">getNextToken</span><span class="p">();</span>
    <span class="p">}</span>
    <span class="k">break</span><span class="p">;</span>
  <span class="p">}</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="sc">&#39;(&#39;</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogErrorP</span><span class="p">(</span><span class="s">&quot;Expected &#39;(&#39; in prototype&quot;</span><span class="p">);</span>

  <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">&gt;</span> <span class="n">ArgNames</span><span class="p">;</span>
  <span class="k">while</span> <span class="p">(</span><span class="n">getNextToken</span><span class="p">()</span> <span class="o">==</span> <span class="n">tok_identifier</span><span class="p">)</span>
    <span class="n">ArgNames</span><span class="p">.</span><span class="n">push_back</span><span class="p">(</span><span class="n">IdentifierStr</span><span class="p">);</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">CurTok</span> <span class="o">!=</span> <span class="sc">&#39;)&#39;</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogErrorP</span><span class="p">(</span><span class="s">&quot;Expected &#39;)&#39; in prototype&quot;</span><span class="p">);</span>

  <span class="c1">// success.</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat &#39;)&#39;.</span>

  <span class="c1">// Verify right number of names for operator.</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">Kind</span> <span class="o">&amp;&amp;</span> <span class="n">ArgNames</span><span class="p">.</span><span class="n">size</span><span class="p">()</span> <span class="o">!=</span> <span class="n">Kind</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogErrorP</span><span class="p">(</span><span class="s">&quot;Invalid number of operands for operator&quot;</span><span class="p">);</span>

  <span class="k">return</span> <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">PrototypeAST</span><span class="o">&gt;</span><span class="p">(</span><span class="n">FnName</span><span class="p">,</span> <span class="n">ArgNames</span><span class="p">,</span> <span class="n">Kind</span> <span class="o">!=</span> <span class="mi">0</span><span class="p">,</span>
                                         <span class="n">BinaryPrecedence</span><span class="p">);</span>
<span class="p">}</span>

<span class="c1">/// definition ::= &#39;def&#39; prototype expression</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">FunctionAST</span><span class="o">&gt;</span> <span class="n">ParseDefinition</span><span class="p">()</span> <span class="p">{</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat def.</span>
  <span class="k">auto</span> <span class="n">Proto</span> <span class="o">=</span> <span class="n">ParsePrototype</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">Proto</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="k">if</span> <span class="p">(</span><span class="k">auto</span> <span class="n">E</span> <span class="o">=</span> <span class="n">ParseExpression</span><span class="p">())</span>
    <span class="k">return</span> <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">FunctionAST</span><span class="o">&gt;</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Proto</span><span class="p">),</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">E</span><span class="p">));</span>
  <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
<span class="p">}</span>

<span class="c1">/// toplevelexpr ::= expression</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">FunctionAST</span><span class="o">&gt;</span> <span class="n">ParseTopLevelExpr</span><span class="p">()</span> <span class="p">{</span>
  <span class="k">if</span> <span class="p">(</span><span class="k">auto</span> <span class="n">E</span> <span class="o">=</span> <span class="n">ParseExpression</span><span class="p">())</span> <span class="p">{</span>
    <span class="c1">// Make an anonymous proto.</span>
    <span class="k">auto</span> <span class="n">Proto</span> <span class="o">=</span> <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">PrototypeAST</span><span class="o">&gt;</span><span class="p">(</span><span class="s">&quot;__anon_expr&quot;</span><span class="p">,</span>
                                                 <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">&gt;</span><span class="p">());</span>
    <span class="k">return</span> <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">FunctionAST</span><span class="o">&gt;</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Proto</span><span class="p">),</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">E</span><span class="p">));</span>
  <span class="p">}</span>
  <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
<span class="p">}</span>

<span class="c1">/// external ::= &#39;extern&#39; prototype</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">PrototypeAST</span><span class="o">&gt;</span> <span class="n">ParseExtern</span><span class="p">()</span> <span class="p">{</span>
  <span class="n">getNextToken</span><span class="p">();</span> <span class="c1">// eat extern.</span>
  <span class="k">return</span> <span class="nf">ParsePrototype</span><span class="p">();</span>
<span class="p">}</span>

<span class="c1">//===----------------------------------------------------------------------===//</span>
<span class="c1">// Code Generation</span>
<span class="c1">//===----------------------------------------------------------------------===//</span>

<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">LLVMContext</span><span class="o">&gt;</span> <span class="n">TheContext</span><span class="p">;</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">Module</span><span class="o">&gt;</span> <span class="n">TheModule</span><span class="p">;</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">IRBuilder</span><span class="o">&lt;&gt;&gt;</span> <span class="n">Builder</span><span class="p">;</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">map</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="p">,</span> <span class="n">AllocaInst</span> <span class="o">*&gt;</span> <span class="n">NamedValues</span><span class="p">;</span>
<span class="k">static</span> <span class="n">std</span><span class="o">::</span><span class="n">map</span><span class="o">&lt;</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="p">,</span> <span class="n">std</span><span class="o">::</span><span class="n">unique_ptr</span><span class="o">&lt;</span><span class="n">PrototypeAST</span><span class="o">&gt;&gt;</span> <span class="n">FunctionProtos</span><span class="p">;</span>
<span class="k">static</span> <span class="n">ExitOnError</span> <span class="n">ExitOnErr</span><span class="p">;</span>

<span class="n">Value</span> <span class="o">*</span><span class="nf">LogErrorV</span><span class="p">(</span><span class="k">const</span> <span class="kt">char</span> <span class="o">*</span><span class="n">Str</span><span class="p">)</span> <span class="p">{</span>
  <span class="n">LogError</span><span class="p">(</span><span class="n">Str</span><span class="p">);</span>
  <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
<span class="p">}</span>

<span class="n">Function</span> <span class="o">*</span><span class="nf">getFunction</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">Name</span><span class="p">)</span> <span class="p">{</span>
  <span class="c1">// First, see if the function has already been added to the current module.</span>
  <span class="k">if</span> <span class="p">(</span><span class="k">auto</span> <span class="o">*</span><span class="n">F</span> <span class="o">=</span> <span class="n">TheModule</span><span class="o">-&gt;</span><span class="n">getFunction</span><span class="p">(</span><span class="n">Name</span><span class="p">))</span>
    <span class="k">return</span> <span class="n">F</span><span class="p">;</span>

  <span class="c1">// If not, check whether we can codegen the declaration from some existing</span>
  <span class="c1">// prototype.</span>
  <span class="k">auto</span> <span class="n">FI</span> <span class="o">=</span> <span class="n">FunctionProtos</span><span class="p">.</span><span class="n">find</span><span class="p">(</span><span class="n">Name</span><span class="p">);</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">FI</span> <span class="o">!=</span> <span class="n">FunctionProtos</span><span class="p">.</span><span class="n">end</span><span class="p">())</span>
    <span class="k">return</span> <span class="n">FI</span><span class="o">-&gt;</span><span class="n">second</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">();</span>

  <span class="c1">// If no existing prototype exists, return null.</span>
  <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
<span class="p">}</span>

<span class="c1">/// CreateEntryBlockAlloca - Create an alloca instruction in the entry block of</span>
<span class="c1">/// the function.  This is used for mutable variables etc.</span>
<span class="k">static</span> <span class="n">AllocaInst</span> <span class="o">*</span><span class="n">CreateEntryBlockAlloca</span><span class="p">(</span><span class="n">Function</span> <span class="o">*</span><span class="n">TheFunction</span><span class="p">,</span>
                                          <span class="n">StringRef</span> <span class="n">VarName</span><span class="p">)</span> <span class="p">{</span>
  <span class="n">IRBuilder</span><span class="o">&lt;&gt;</span> <span class="n">TmpB</span><span class="p">(</span><span class="o">&amp;</span><span class="n">TheFunction</span><span class="o">-&gt;</span><span class="n">getEntryBlock</span><span class="p">(),</span>
                   <span class="n">TheFunction</span><span class="o">-&gt;</span><span class="n">getEntryBlock</span><span class="p">().</span><span class="n">begin</span><span class="p">());</span>
  <span class="k">return</span> <span class="n">TmpB</span><span class="p">.</span><span class="n">CreateAlloca</span><span class="p">(</span><span class="n">Type</span><span class="o">::</span><span class="n">getDoubleTy</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">),</span> <span class="k">nullptr</span><span class="p">,</span> <span class="n">VarName</span><span class="p">);</span>
<span class="p">}</span>

<span class="n">Value</span> <span class="o">*</span><span class="n">NumberExprAST</span><span class="o">::</span><span class="n">codegen</span><span class="p">()</span> <span class="p">{</span>
  <span class="k">return</span> <span class="n">ConstantFP</span><span class="o">::</span><span class="n">get</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">,</span> <span class="n">APFloat</span><span class="p">(</span><span class="n">Val</span><span class="p">));</span>
<span class="p">}</span>

<span class="n">Value</span> <span class="o">*</span><span class="n">VariableExprAST</span><span class="o">::</span><span class="n">codegen</span><span class="p">()</span> <span class="p">{</span>
  <span class="c1">// Look this variable up in the function.</span>
  <span class="n">Value</span> <span class="o">*</span><span class="n">V</span> <span class="o">=</span> <span class="n">NamedValues</span><span class="p">[</span><span class="n">Name</span><span class="p">];</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">V</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogErrorV</span><span class="p">(</span><span class="s">&quot;Unknown variable name&quot;</span><span class="p">);</span>

  <span class="c1">// Load the value.</span>
  <span class="k">return</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateLoad</span><span class="p">(</span><span class="n">Type</span><span class="o">::</span><span class="n">getDoubleTy</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">),</span> <span class="n">V</span><span class="p">,</span> <span class="n">Name</span><span class="p">.</span><span class="n">c_str</span><span class="p">());</span>
<span class="p">}</span>

<span class="n">Value</span> <span class="o">*</span><span class="n">UnaryExprAST</span><span class="o">::</span><span class="n">codegen</span><span class="p">()</span> <span class="p">{</span>
  <span class="n">Value</span> <span class="o">*</span><span class="n">OperandV</span> <span class="o">=</span> <span class="n">Operand</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">OperandV</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="n">Function</span> <span class="o">*</span><span class="n">F</span> <span class="o">=</span> <span class="n">getFunction</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="p">(</span><span class="s">&quot;unary&quot;</span><span class="p">)</span> <span class="o">+</span> <span class="n">Opcode</span><span class="p">);</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">F</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogErrorV</span><span class="p">(</span><span class="s">&quot;Unknown unary operator&quot;</span><span class="p">);</span>

  <span class="k">return</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateCall</span><span class="p">(</span><span class="n">F</span><span class="p">,</span> <span class="n">OperandV</span><span class="p">,</span> <span class="s">&quot;unop&quot;</span><span class="p">);</span>
<span class="p">}</span>

<span class="n">Value</span> <span class="o">*</span><span class="n">BinaryExprAST</span><span class="o">::</span><span class="n">codegen</span><span class="p">()</span> <span class="p">{</span>
  <span class="c1">// Special case &#39;=&#39; because we don&#39;t want to emit the LHS as an expression.</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">Op</span> <span class="o">==</span> <span class="sc">&#39;=&#39;</span><span class="p">)</span> <span class="p">{</span>
    <span class="c1">// Assignment requires the LHS to be an identifier.</span>
    <span class="c1">// This assume we&#39;re building without RTTI because LLVM builds that way by</span>
    <span class="c1">// default.  If you build LLVM with RTTI this can be changed to a</span>
    <span class="c1">// dynamic_cast for automatic error checking.</span>
    <span class="n">VariableExprAST</span> <span class="o">*</span><span class="n">LHSE</span> <span class="o">=</span> <span class="k">static_cast</span><span class="o">&lt;</span><span class="n">VariableExprAST</span> <span class="o">*&gt;</span><span class="p">(</span><span class="n">LHS</span><span class="p">.</span><span class="n">get</span><span class="p">());</span>
    <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">LHSE</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">LogErrorV</span><span class="p">(</span><span class="s">&quot;destination of &#39;=&#39; must be a variable&quot;</span><span class="p">);</span>
    <span class="c1">// Codegen the RHS.</span>
    <span class="n">Value</span> <span class="o">*</span><span class="n">Val</span> <span class="o">=</span> <span class="n">RHS</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">();</span>
    <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">Val</span><span class="p">)</span>
      <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

    <span class="c1">// Look up the name.</span>
    <span class="n">Value</span> <span class="o">*</span><span class="n">Variable</span> <span class="o">=</span> <span class="n">NamedValues</span><span class="p">[</span><span class="n">LHSE</span><span class="o">-&gt;</span><span class="n">getName</span><span class="p">()];</span>
    <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">Variable</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">LogErrorV</span><span class="p">(</span><span class="s">&quot;Unknown variable name&quot;</span><span class="p">);</span>

    <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateStore</span><span class="p">(</span><span class="n">Val</span><span class="p">,</span> <span class="n">Variable</span><span class="p">);</span>
    <span class="k">return</span> <span class="n">Val</span><span class="p">;</span>
  <span class="p">}</span>

  <span class="n">Value</span> <span class="o">*</span><span class="n">L</span> <span class="o">=</span> <span class="n">LHS</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">();</span>
  <span class="n">Value</span> <span class="o">*</span><span class="n">R</span> <span class="o">=</span> <span class="n">RHS</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">L</span> <span class="o">||</span> <span class="o">!</span><span class="n">R</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="k">switch</span> <span class="p">(</span><span class="n">Op</span><span class="p">)</span> <span class="p">{</span>
  <span class="k">case</span> <span class="sc">&#39;+&#39;</span><span class="o">:</span>
    <span class="k">return</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateFAdd</span><span class="p">(</span><span class="n">L</span><span class="p">,</span> <span class="n">R</span><span class="p">,</span> <span class="s">&quot;addtmp&quot;</span><span class="p">);</span>
  <span class="k">case</span> <span class="sc">&#39;-&#39;</span><span class="o">:</span>
    <span class="k">return</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateFSub</span><span class="p">(</span><span class="n">L</span><span class="p">,</span> <span class="n">R</span><span class="p">,</span> <span class="s">&quot;subtmp&quot;</span><span class="p">);</span>
  <span class="k">case</span> <span class="sc">&#39;*&#39;</span><span class="o">:</span>
    <span class="k">return</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateFMul</span><span class="p">(</span><span class="n">L</span><span class="p">,</span> <span class="n">R</span><span class="p">,</span> <span class="s">&quot;multmp&quot;</span><span class="p">);</span>
  <span class="k">case</span> <span class="sc">&#39;&lt;&#39;</span><span class="o">:</span>
    <span class="n">L</span> <span class="o">=</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateFCmpULT</span><span class="p">(</span><span class="n">L</span><span class="p">,</span> <span class="n">R</span><span class="p">,</span> <span class="s">&quot;cmptmp&quot;</span><span class="p">);</span>
    <span class="c1">// Convert bool 0/1 to double 0.0 or 1.0</span>
    <span class="k">return</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateUIToFP</span><span class="p">(</span><span class="n">L</span><span class="p">,</span> <span class="n">Type</span><span class="o">::</span><span class="n">getDoubleTy</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">),</span> <span class="s">&quot;booltmp&quot;</span><span class="p">);</span>
  <span class="k">default</span><span class="o">:</span>
    <span class="k">break</span><span class="p">;</span>
  <span class="p">}</span>

  <span class="c1">// If it wasn&#39;t a builtin binary operator, it must be a user defined one. Emit</span>
  <span class="c1">// a call to it.</span>
  <span class="n">Function</span> <span class="o">*</span><span class="n">F</span> <span class="o">=</span> <span class="n">getFunction</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="p">(</span><span class="s">&quot;binary&quot;</span><span class="p">)</span> <span class="o">+</span> <span class="n">Op</span><span class="p">);</span>
  <span class="n">assert</span><span class="p">(</span><span class="n">F</span> <span class="o">&amp;&amp;</span> <span class="s">&quot;binary operator not found!&quot;</span><span class="p">);</span>

  <span class="n">Value</span> <span class="o">*</span><span class="n">Ops</span><span class="p">[]</span> <span class="o">=</span> <span class="p">{</span><span class="n">L</span><span class="p">,</span> <span class="n">R</span><span class="p">};</span>
  <span class="k">return</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateCall</span><span class="p">(</span><span class="n">F</span><span class="p">,</span> <span class="n">Ops</span><span class="p">,</span> <span class="s">&quot;binop&quot;</span><span class="p">);</span>
<span class="p">}</span>

<span class="n">Value</span> <span class="o">*</span><span class="n">CallExprAST</span><span class="o">::</span><span class="n">codegen</span><span class="p">()</span> <span class="p">{</span>
  <span class="c1">// Look up the name in the global module table.</span>
  <span class="n">Function</span> <span class="o">*</span><span class="n">CalleeF</span> <span class="o">=</span> <span class="n">getFunction</span><span class="p">(</span><span class="n">Callee</span><span class="p">);</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">CalleeF</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">LogErrorV</span><span class="p">(</span><span class="s">&quot;Unknown function referenced&quot;</span><span class="p">);</span>

  <span class="c1">// If argument mismatch error.</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">CalleeF</span><span class="o">-&gt;</span><span class="n">arg_size</span><span class="p">()</span> <span class="o">!=</span> <span class="n">Args</span><span class="p">.</span><span class="n">size</span><span class="p">())</span>
    <span class="k">return</span> <span class="n">LogErrorV</span><span class="p">(</span><span class="s">&quot;Incorrect # arguments passed&quot;</span><span class="p">);</span>

  <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">Value</span> <span class="o">*&gt;</span> <span class="n">ArgsV</span><span class="p">;</span>
  <span class="k">for</span> <span class="p">(</span><span class="kt">unsigned</span> <span class="n">i</span> <span class="o">=</span> <span class="mi">0</span><span class="p">,</span> <span class="n">e</span> <span class="o">=</span> <span class="n">Args</span><span class="p">.</span><span class="n">size</span><span class="p">();</span> <span class="n">i</span> <span class="o">!=</span> <span class="n">e</span><span class="p">;</span> <span class="o">++</span><span class="n">i</span><span class="p">)</span> <span class="p">{</span>
    <span class="n">ArgsV</span><span class="p">.</span><span class="n">push_back</span><span class="p">(</span><span class="n">Args</span><span class="p">[</span><span class="n">i</span><span class="p">]</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">());</span>
    <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">ArgsV</span><span class="p">.</span><span class="n">back</span><span class="p">())</span>
      <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
  <span class="p">}</span>

  <span class="k">return</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateCall</span><span class="p">(</span><span class="n">CalleeF</span><span class="p">,</span> <span class="n">ArgsV</span><span class="p">,</span> <span class="s">&quot;calltmp&quot;</span><span class="p">);</span>
<span class="p">}</span>

<span class="n">Value</span> <span class="o">*</span><span class="n">IfExprAST</span><span class="o">::</span><span class="n">codegen</span><span class="p">()</span> <span class="p">{</span>
  <span class="n">Value</span> <span class="o">*</span><span class="n">CondV</span> <span class="o">=</span> <span class="n">Cond</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">CondV</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="c1">// Convert condition to a bool by comparing non-equal to 0.0.</span>
  <span class="n">CondV</span> <span class="o">=</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateFCmpONE</span><span class="p">(</span>
      <span class="n">CondV</span><span class="p">,</span> <span class="n">ConstantFP</span><span class="o">::</span><span class="n">get</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">,</span> <span class="n">APFloat</span><span class="p">(</span><span class="mf">0.0</span><span class="p">)),</span> <span class="s">&quot;ifcond&quot;</span><span class="p">);</span>

  <span class="n">Function</span> <span class="o">*</span><span class="n">TheFunction</span> <span class="o">=</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">GetInsertBlock</span><span class="p">()</span><span class="o">-&gt;</span><span class="n">getParent</span><span class="p">();</span>

  <span class="c1">// Create blocks for the then and else cases.  Insert the &#39;then&#39; block at the</span>
  <span class="c1">// end of the function.</span>
  <span class="n">BasicBlock</span> <span class="o">*</span><span class="n">ThenBB</span> <span class="o">=</span> <span class="n">BasicBlock</span><span class="o">::</span><span class="n">Create</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">,</span> <span class="s">&quot;then&quot;</span><span class="p">,</span> <span class="n">TheFunction</span><span class="p">);</span>
  <span class="n">BasicBlock</span> <span class="o">*</span><span class="n">ElseBB</span> <span class="o">=</span> <span class="n">BasicBlock</span><span class="o">::</span><span class="n">Create</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">,</span> <span class="s">&quot;else&quot;</span><span class="p">);</span>
  <span class="n">BasicBlock</span> <span class="o">*</span><span class="n">MergeBB</span> <span class="o">=</span> <span class="n">BasicBlock</span><span class="o">::</span><span class="n">Create</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">,</span> <span class="s">&quot;ifcont&quot;</span><span class="p">);</span>

  <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateCondBr</span><span class="p">(</span><span class="n">CondV</span><span class="p">,</span> <span class="n">ThenBB</span><span class="p">,</span> <span class="n">ElseBB</span><span class="p">);</span>

  <span class="c1">// Emit then value.</span>
  <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">SetInsertPoint</span><span class="p">(</span><span class="n">ThenBB</span><span class="p">);</span>

  <span class="n">Value</span> <span class="o">*</span><span class="n">ThenV</span> <span class="o">=</span> <span class="n">Then</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">ThenV</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateBr</span><span class="p">(</span><span class="n">MergeBB</span><span class="p">);</span>
  <span class="c1">// Codegen of &#39;Then&#39; can change the current block, update ThenBB for the PHI.</span>
  <span class="n">ThenBB</span> <span class="o">=</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">GetInsertBlock</span><span class="p">();</span>

  <span class="c1">// Emit else block.</span>
  <span class="n">TheFunction</span><span class="o">-&gt;</span><span class="n">getBasicBlockList</span><span class="p">().</span><span class="n">push_back</span><span class="p">(</span><span class="n">ElseBB</span><span class="p">);</span>
  <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">SetInsertPoint</span><span class="p">(</span><span class="n">ElseBB</span><span class="p">);</span>

  <span class="n">Value</span> <span class="o">*</span><span class="n">ElseV</span> <span class="o">=</span> <span class="n">Else</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">ElseV</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateBr</span><span class="p">(</span><span class="n">MergeBB</span><span class="p">);</span>
  <span class="c1">// Codegen of &#39;Else&#39; can change the current block, update ElseBB for the PHI.</span>
  <span class="n">ElseBB</span> <span class="o">=</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">GetInsertBlock</span><span class="p">();</span>

  <span class="c1">// Emit merge block.</span>
  <span class="n">TheFunction</span><span class="o">-&gt;</span><span class="n">getBasicBlockList</span><span class="p">().</span><span class="n">push_back</span><span class="p">(</span><span class="n">MergeBB</span><span class="p">);</span>
  <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">SetInsertPoint</span><span class="p">(</span><span class="n">MergeBB</span><span class="p">);</span>
  <span class="n">PHINode</span> <span class="o">*</span><span class="n">PN</span> <span class="o">=</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreatePHI</span><span class="p">(</span><span class="n">Type</span><span class="o">::</span><span class="n">getDoubleTy</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">),</span> <span class="mi">2</span><span class="p">,</span> <span class="s">&quot;iftmp&quot;</span><span class="p">);</span>

  <span class="n">PN</span><span class="o">-&gt;</span><span class="n">addIncoming</span><span class="p">(</span><span class="n">ThenV</span><span class="p">,</span> <span class="n">ThenBB</span><span class="p">);</span>
  <span class="n">PN</span><span class="o">-&gt;</span><span class="n">addIncoming</span><span class="p">(</span><span class="n">ElseV</span><span class="p">,</span> <span class="n">ElseBB</span><span class="p">);</span>
  <span class="k">return</span> <span class="n">PN</span><span class="p">;</span>
<span class="p">}</span>

<span class="c1">// Output for-loop as:</span>
<span class="c1">//   var = alloca double</span>
<span class="c1">//   ...</span>
<span class="c1">//   start = startexpr</span>
<span class="c1">//   store start -&gt; var</span>
<span class="c1">//   goto loop</span>
<span class="c1">// loop:</span>
<span class="c1">//   ...</span>
<span class="c1">//   bodyexpr</span>
<span class="c1">//   ...</span>
<span class="c1">// loopend:</span>
<span class="c1">//   step = stepexpr</span>
<span class="c1">//   endcond = endexpr</span>
<span class="c1">//</span>
<span class="c1">//   curvar = load var</span>
<span class="c1">//   nextvar = curvar + step</span>
<span class="c1">//   store nextvar -&gt; var</span>
<span class="c1">//   br endcond, loop, endloop</span>
<span class="c1">// outloop:</span>
<span class="n">Value</span> <span class="o">*</span><span class="n">ForExprAST</span><span class="o">::</span><span class="n">codegen</span><span class="p">()</span> <span class="p">{</span>
  <span class="n">Function</span> <span class="o">*</span><span class="n">TheFunction</span> <span class="o">=</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">GetInsertBlock</span><span class="p">()</span><span class="o">-&gt;</span><span class="n">getParent</span><span class="p">();</span>

  <span class="c1">// Create an alloca for the variable in the entry block.</span>
  <span class="n">AllocaInst</span> <span class="o">*</span><span class="n">Alloca</span> <span class="o">=</span> <span class="n">CreateEntryBlockAlloca</span><span class="p">(</span><span class="n">TheFunction</span><span class="p">,</span> <span class="n">VarName</span><span class="p">);</span>

  <span class="c1">// Emit the start code first, without &#39;variable&#39; in scope.</span>
  <span class="n">Value</span> <span class="o">*</span><span class="n">StartVal</span> <span class="o">=</span> <span class="n">Start</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">StartVal</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="c1">// Store the value into the alloca.</span>
  <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateStore</span><span class="p">(</span><span class="n">StartVal</span><span class="p">,</span> <span class="n">Alloca</span><span class="p">);</span>

  <span class="c1">// Make the new basic block for the loop header, inserting after current</span>
  <span class="c1">// block.</span>
  <span class="n">BasicBlock</span> <span class="o">*</span><span class="n">LoopBB</span> <span class="o">=</span> <span class="n">BasicBlock</span><span class="o">::</span><span class="n">Create</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">,</span> <span class="s">&quot;loop&quot;</span><span class="p">,</span> <span class="n">TheFunction</span><span class="p">);</span>

  <span class="c1">// Insert an explicit fall through from the current block to the LoopBB.</span>
  <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateBr</span><span class="p">(</span><span class="n">LoopBB</span><span class="p">);</span>

  <span class="c1">// Start insertion in LoopBB.</span>
  <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">SetInsertPoint</span><span class="p">(</span><span class="n">LoopBB</span><span class="p">);</span>

  <span class="c1">// Within the loop, the variable is defined equal to the PHI node.  If it</span>
  <span class="c1">// shadows an existing variable, we have to restore it, so save it now.</span>
  <span class="n">AllocaInst</span> <span class="o">*</span><span class="n">OldVal</span> <span class="o">=</span> <span class="n">NamedValues</span><span class="p">[</span><span class="n">VarName</span><span class="p">];</span>
  <span class="n">NamedValues</span><span class="p">[</span><span class="n">VarName</span><span class="p">]</span> <span class="o">=</span> <span class="n">Alloca</span><span class="p">;</span>

  <span class="c1">// Emit the body of the loop.  This, like any other expr, can change the</span>
  <span class="c1">// current BB.  Note that we ignore the value computed by the body, but don&#39;t</span>
  <span class="c1">// allow an error.</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">Body</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">())</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="c1">// Emit the step value.</span>
  <span class="n">Value</span> <span class="o">*</span><span class="n">StepVal</span> <span class="o">=</span> <span class="k">nullptr</span><span class="p">;</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">Step</span><span class="p">)</span> <span class="p">{</span>
    <span class="n">StepVal</span> <span class="o">=</span> <span class="n">Step</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">();</span>
    <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">StepVal</span><span class="p">)</span>
      <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
  <span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
    <span class="c1">// If not specified, use 1.0.</span>
    <span class="n">StepVal</span> <span class="o">=</span> <span class="n">ConstantFP</span><span class="o">::</span><span class="n">get</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">,</span> <span class="n">APFloat</span><span class="p">(</span><span class="mf">1.0</span><span class="p">));</span>
  <span class="p">}</span>

  <span class="c1">// Compute the end condition.</span>
  <span class="n">Value</span> <span class="o">*</span><span class="n">EndCond</span> <span class="o">=</span> <span class="n">End</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">EndCond</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="c1">// Reload, increment, and restore the alloca.  This handles the case where</span>
  <span class="c1">// the body of the loop mutates the variable.</span>
  <span class="n">Value</span> <span class="o">*</span><span class="n">CurVar</span> <span class="o">=</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateLoad</span><span class="p">(</span><span class="n">Type</span><span class="o">::</span><span class="n">getDoubleTy</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">),</span> <span class="n">Alloca</span><span class="p">,</span>
                                      <span class="n">VarName</span><span class="p">.</span><span class="n">c_str</span><span class="p">());</span>
  <span class="n">Value</span> <span class="o">*</span><span class="n">NextVar</span> <span class="o">=</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateFAdd</span><span class="p">(</span><span class="n">CurVar</span><span class="p">,</span> <span class="n">StepVal</span><span class="p">,</span> <span class="s">&quot;nextvar&quot;</span><span class="p">);</span>
  <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateStore</span><span class="p">(</span><span class="n">NextVar</span><span class="p">,</span> <span class="n">Alloca</span><span class="p">);</span>

  <span class="c1">// Convert condition to a bool by comparing non-equal to 0.0.</span>
  <span class="n">EndCond</span> <span class="o">=</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateFCmpONE</span><span class="p">(</span>
      <span class="n">EndCond</span><span class="p">,</span> <span class="n">ConstantFP</span><span class="o">::</span><span class="n">get</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">,</span> <span class="n">APFloat</span><span class="p">(</span><span class="mf">0.0</span><span class="p">)),</span> <span class="s">&quot;loopcond&quot;</span><span class="p">);</span>

  <span class="c1">// Create the &quot;after loop&quot; block and insert it.</span>
  <span class="n">BasicBlock</span> <span class="o">*</span><span class="n">AfterBB</span> <span class="o">=</span>
      <span class="n">BasicBlock</span><span class="o">::</span><span class="n">Create</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">,</span> <span class="s">&quot;afterloop&quot;</span><span class="p">,</span> <span class="n">TheFunction</span><span class="p">);</span>

  <span class="c1">// Insert the conditional branch into the end of LoopEndBB.</span>
  <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateCondBr</span><span class="p">(</span><span class="n">EndCond</span><span class="p">,</span> <span class="n">LoopBB</span><span class="p">,</span> <span class="n">AfterBB</span><span class="p">);</span>

  <span class="c1">// Any new code will be inserted in AfterBB.</span>
  <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">SetInsertPoint</span><span class="p">(</span><span class="n">AfterBB</span><span class="p">);</span>

  <span class="c1">// Restore the unshadowed variable.</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">OldVal</span><span class="p">)</span>
    <span class="n">NamedValues</span><span class="p">[</span><span class="n">VarName</span><span class="p">]</span> <span class="o">=</span> <span class="n">OldVal</span><span class="p">;</span>
  <span class="k">else</span>
    <span class="n">NamedValues</span><span class="p">.</span><span class="n">erase</span><span class="p">(</span><span class="n">VarName</span><span class="p">);</span>

  <span class="c1">// for expr always returns 0.0.</span>
  <span class="k">return</span> <span class="n">Constant</span><span class="o">::</span><span class="n">getNullValue</span><span class="p">(</span><span class="n">Type</span><span class="o">::</span><span class="n">getDoubleTy</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">));</span>
<span class="p">}</span>

<span class="n">Value</span> <span class="o">*</span><span class="n">VarExprAST</span><span class="o">::</span><span class="n">codegen</span><span class="p">()</span> <span class="p">{</span>
  <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">AllocaInst</span> <span class="o">*&gt;</span> <span class="n">OldBindings</span><span class="p">;</span>

  <span class="n">Function</span> <span class="o">*</span><span class="n">TheFunction</span> <span class="o">=</span> <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">GetInsertBlock</span><span class="p">()</span><span class="o">-&gt;</span><span class="n">getParent</span><span class="p">();</span>

  <span class="c1">// Register all variables and emit their initializer.</span>
  <span class="k">for</span> <span class="p">(</span><span class="kt">unsigned</span> <span class="n">i</span> <span class="o">=</span> <span class="mi">0</span><span class="p">,</span> <span class="n">e</span> <span class="o">=</span> <span class="n">VarNames</span><span class="p">.</span><span class="n">size</span><span class="p">();</span> <span class="n">i</span> <span class="o">!=</span> <span class="n">e</span><span class="p">;</span> <span class="o">++</span><span class="n">i</span><span class="p">)</span> <span class="p">{</span>
    <span class="k">const</span> <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="o">&amp;</span><span class="n">VarName</span> <span class="o">=</span> <span class="n">VarNames</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">first</span><span class="p">;</span>
    <span class="n">ExprAST</span> <span class="o">*</span><span class="n">Init</span> <span class="o">=</span> <span class="n">VarNames</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">second</span><span class="p">.</span><span class="n">get</span><span class="p">();</span>

    <span class="c1">// Emit the initializer before adding the variable to scope, this prevents</span>
    <span class="c1">// the initializer from referencing the variable itself, and permits stuff</span>
    <span class="c1">// like this:</span>
    <span class="c1">//  var a = 1 in</span>
    <span class="c1">//    var a = a in ...   # refers to outer &#39;a&#39;.</span>
    <span class="n">Value</span> <span class="o">*</span><span class="n">InitVal</span><span class="p">;</span>
    <span class="k">if</span> <span class="p">(</span><span class="n">Init</span><span class="p">)</span> <span class="p">{</span>
      <span class="n">InitVal</span> <span class="o">=</span> <span class="n">Init</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">();</span>
      <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">InitVal</span><span class="p">)</span>
        <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
    <span class="p">}</span> <span class="k">else</span> <span class="p">{</span> <span class="c1">// If not specified, use 0.0.</span>
      <span class="n">InitVal</span> <span class="o">=</span> <span class="n">ConstantFP</span><span class="o">::</span><span class="n">get</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">,</span> <span class="n">APFloat</span><span class="p">(</span><span class="mf">0.0</span><span class="p">));</span>
    <span class="p">}</span>

    <span class="n">AllocaInst</span> <span class="o">*</span><span class="n">Alloca</span> <span class="o">=</span> <span class="n">CreateEntryBlockAlloca</span><span class="p">(</span><span class="n">TheFunction</span><span class="p">,</span> <span class="n">VarName</span><span class="p">);</span>
    <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateStore</span><span class="p">(</span><span class="n">InitVal</span><span class="p">,</span> <span class="n">Alloca</span><span class="p">);</span>

    <span class="c1">// Remember the old variable binding so that we can restore the binding when</span>
    <span class="c1">// we unrecurse.</span>
    <span class="n">OldBindings</span><span class="p">.</span><span class="n">push_back</span><span class="p">(</span><span class="n">NamedValues</span><span class="p">[</span><span class="n">VarName</span><span class="p">]);</span>

    <span class="c1">// Remember this binding.</span>
    <span class="n">NamedValues</span><span class="p">[</span><span class="n">VarName</span><span class="p">]</span> <span class="o">=</span> <span class="n">Alloca</span><span class="p">;</span>
  <span class="p">}</span>

  <span class="c1">// Codegen the body, now that all vars are in scope.</span>
  <span class="n">Value</span> <span class="o">*</span><span class="n">BodyVal</span> <span class="o">=</span> <span class="n">Body</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">BodyVal</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="c1">// Pop all our variables from scope.</span>
  <span class="k">for</span> <span class="p">(</span><span class="kt">unsigned</span> <span class="n">i</span> <span class="o">=</span> <span class="mi">0</span><span class="p">,</span> <span class="n">e</span> <span class="o">=</span> <span class="n">VarNames</span><span class="p">.</span><span class="n">size</span><span class="p">();</span> <span class="n">i</span> <span class="o">!=</span> <span class="n">e</span><span class="p">;</span> <span class="o">++</span><span class="n">i</span><span class="p">)</span>
    <span class="n">NamedValues</span><span class="p">[</span><span class="n">VarNames</span><span class="p">[</span><span class="n">i</span><span class="p">].</span><span class="n">first</span><span class="p">]</span> <span class="o">=</span> <span class="n">OldBindings</span><span class="p">[</span><span class="n">i</span><span class="p">];</span>

  <span class="c1">// Return the body computation.</span>
  <span class="k">return</span> <span class="n">BodyVal</span><span class="p">;</span>
<span class="p">}</span>

<span class="n">Function</span> <span class="o">*</span><span class="n">PrototypeAST</span><span class="o">::</span><span class="n">codegen</span><span class="p">()</span> <span class="p">{</span>
  <span class="c1">// Make the function type:  double(double,double) etc.</span>
  <span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o">&lt;</span><span class="n">Type</span> <span class="o">*&gt;</span> <span class="n">Doubles</span><span class="p">(</span><span class="n">Args</span><span class="p">.</span><span class="n">size</span><span class="p">(),</span> <span class="n">Type</span><span class="o">::</span><span class="n">getDoubleTy</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">));</span>
  <span class="n">FunctionType</span> <span class="o">*</span><span class="n">FT</span> <span class="o">=</span>
      <span class="n">FunctionType</span><span class="o">::</span><span class="n">get</span><span class="p">(</span><span class="n">Type</span><span class="o">::</span><span class="n">getDoubleTy</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">),</span> <span class="n">Doubles</span><span class="p">,</span> <span class="nb">false</span><span class="p">);</span>

  <span class="n">Function</span> <span class="o">*</span><span class="n">F</span> <span class="o">=</span>
      <span class="n">Function</span><span class="o">::</span><span class="n">Create</span><span class="p">(</span><span class="n">FT</span><span class="p">,</span> <span class="n">Function</span><span class="o">::</span><span class="n">ExternalLinkage</span><span class="p">,</span> <span class="n">Name</span><span class="p">,</span> <span class="n">TheModule</span><span class="p">.</span><span class="n">get</span><span class="p">());</span>

  <span class="c1">// Set names for all arguments.</span>
  <span class="kt">unsigned</span> <span class="n">Idx</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
  <span class="k">for</span> <span class="p">(</span><span class="k">auto</span> <span class="o">&amp;</span><span class="nl">Arg</span> <span class="p">:</span> <span class="n">F</span><span class="o">-&gt;</span><span class="n">args</span><span class="p">())</span>
    <span class="n">Arg</span><span class="p">.</span><span class="n">setName</span><span class="p">(</span><span class="n">Args</span><span class="p">[</span><span class="n">Idx</span><span class="o">++</span><span class="p">]);</span>

  <span class="k">return</span> <span class="n">F</span><span class="p">;</span>
<span class="p">}</span>

<span class="n">Function</span> <span class="o">*</span><span class="n">FunctionAST</span><span class="o">::</span><span class="n">codegen</span><span class="p">()</span> <span class="p">{</span>
  <span class="c1">// Transfer ownership of the prototype to the FunctionProtos map, but keep a</span>
  <span class="c1">// reference to it for use below.</span>
  <span class="k">auto</span> <span class="o">&amp;</span><span class="n">P</span> <span class="o">=</span> <span class="o">*</span><span class="n">Proto</span><span class="p">;</span>
  <span class="n">FunctionProtos</span><span class="p">[</span><span class="n">Proto</span><span class="o">-&gt;</span><span class="n">getName</span><span class="p">()]</span> <span class="o">=</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">Proto</span><span class="p">);</span>
  <span class="n">Function</span> <span class="o">*</span><span class="n">TheFunction</span> <span class="o">=</span> <span class="n">getFunction</span><span class="p">(</span><span class="n">P</span><span class="p">.</span><span class="n">getName</span><span class="p">());</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">TheFunction</span><span class="p">)</span>
    <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>

  <span class="c1">// If this is an operator, install it.</span>
  <span class="k">if</span> <span class="p">(</span><span class="n">P</span><span class="p">.</span><span class="n">isBinaryOp</span><span class="p">())</span>
    <span class="n">BinopPrecedence</span><span class="p">[</span><span class="n">P</span><span class="p">.</span><span class="n">getOperatorName</span><span class="p">()]</span> <span class="o">=</span> <span class="n">P</span><span class="p">.</span><span class="n">getBinaryPrecedence</span><span class="p">();</span>

  <span class="c1">// Create a new basic block to start insertion into.</span>
  <span class="n">BasicBlock</span> <span class="o">*</span><span class="n">BB</span> <span class="o">=</span> <span class="n">BasicBlock</span><span class="o">::</span><span class="n">Create</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">,</span> <span class="s">&quot;entry&quot;</span><span class="p">,</span> <span class="n">TheFunction</span><span class="p">);</span>
  <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">SetInsertPoint</span><span class="p">(</span><span class="n">BB</span><span class="p">);</span>

  <span class="c1">// Record the function arguments in the NamedValues map.</span>
  <span class="n">NamedValues</span><span class="p">.</span><span class="n">clear</span><span class="p">();</span>
  <span class="k">for</span> <span class="p">(</span><span class="k">auto</span> <span class="o">&amp;</span><span class="nl">Arg</span> <span class="p">:</span> <span class="n">TheFunction</span><span class="o">-&gt;</span><span class="n">args</span><span class="p">())</span> <span class="p">{</span>
    <span class="c1">// Create an alloca for this variable.</span>
    <span class="n">AllocaInst</span> <span class="o">*</span><span class="n">Alloca</span> <span class="o">=</span> <span class="n">CreateEntryBlockAlloca</span><span class="p">(</span><span class="n">TheFunction</span><span class="p">,</span> <span class="n">Arg</span><span class="p">.</span><span class="n">getName</span><span class="p">());</span>

    <span class="c1">// Store the initial value into the alloca.</span>
    <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateStore</span><span class="p">(</span><span class="o">&amp;</span><span class="n">Arg</span><span class="p">,</span> <span class="n">Alloca</span><span class="p">);</span>

    <span class="c1">// Add arguments to variable symbol table.</span>
    <span class="n">NamedValues</span><span class="p">[</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="p">(</span><span class="n">Arg</span><span class="p">.</span><span class="n">getName</span><span class="p">())]</span> <span class="o">=</span> <span class="n">Alloca</span><span class="p">;</span>
  <span class="p">}</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">Value</span> <span class="o">*</span><span class="n">RetVal</span> <span class="o">=</span> <span class="n">Body</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">())</span> <span class="p">{</span>
    <span class="c1">// Finish off the function.</span>
    <span class="n">Builder</span><span class="o">-&gt;</span><span class="n">CreateRet</span><span class="p">(</span><span class="n">RetVal</span><span class="p">);</span>

    <span class="c1">// Validate the generated code, checking for consistency.</span>
    <span class="n">verifyFunction</span><span class="p">(</span><span class="o">*</span><span class="n">TheFunction</span><span class="p">);</span>

    <span class="k">return</span> <span class="n">TheFunction</span><span class="p">;</span>
  <span class="p">}</span>

  <span class="c1">// Error reading body, remove function.</span>
  <span class="n">TheFunction</span><span class="o">-&gt;</span><span class="n">eraseFromParent</span><span class="p">();</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">P</span><span class="p">.</span><span class="n">isBinaryOp</span><span class="p">())</span>
    <span class="n">BinopPrecedence</span><span class="p">.</span><span class="n">erase</span><span class="p">(</span><span class="n">P</span><span class="p">.</span><span class="n">getOperatorName</span><span class="p">());</span>
  <span class="k">return</span> <span class="k">nullptr</span><span class="p">;</span>
<span class="p">}</span>

<span class="c1">//===----------------------------------------------------------------------===//</span>
<span class="c1">// Top-Level parsing and JIT Driver</span>
<span class="c1">//===----------------------------------------------------------------------===//</span>

<span class="k">static</span> <span class="kt">void</span> <span class="n">InitializeModuleAndPassManager</span><span class="p">()</span> <span class="p">{</span>
  <span class="c1">// Open a new module.</span>
  <span class="n">TheContext</span> <span class="o">=</span> <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">LLVMContext</span><span class="o">&gt;</span><span class="p">();</span>
  <span class="n">TheModule</span> <span class="o">=</span> <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">Module</span><span class="o">&gt;</span><span class="p">(</span><span class="s">&quot;my cool jit&quot;</span><span class="p">,</span> <span class="o">*</span><span class="n">TheContext</span><span class="p">);</span>

  <span class="c1">// Create a new builder for the module.</span>
  <span class="n">Builder</span> <span class="o">=</span> <span class="n">std</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">IRBuilder</span><span class="o">&lt;&gt;&gt;</span><span class="p">(</span><span class="o">*</span><span class="n">TheContext</span><span class="p">);</span>
<span class="p">}</span>

<span class="k">static</span> <span class="kt">void</span> <span class="n">HandleDefinition</span><span class="p">()</span> <span class="p">{</span>
  <span class="k">if</span> <span class="p">(</span><span class="k">auto</span> <span class="n">FnAST</span> <span class="o">=</span> <span class="n">ParseDefinition</span><span class="p">())</span> <span class="p">{</span>
    <span class="k">if</span> <span class="p">(</span><span class="k">auto</span> <span class="o">*</span><span class="n">FnIR</span> <span class="o">=</span> <span class="n">FnAST</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">())</span> <span class="p">{</span>
      <span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;Read function definition:&quot;</span><span class="p">);</span>
      <span class="n">FnIR</span><span class="o">-&gt;</span><span class="n">print</span><span class="p">(</span><span class="n">errs</span><span class="p">());</span>
      <span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">);</span>
    <span class="p">}</span>
  <span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
    <span class="c1">// Skip token for error recovery.</span>
    <span class="n">getNextToken</span><span class="p">();</span>
  <span class="p">}</span>
<span class="p">}</span>

<span class="k">static</span> <span class="kt">void</span> <span class="n">HandleExtern</span><span class="p">()</span> <span class="p">{</span>
  <span class="k">if</span> <span class="p">(</span><span class="k">auto</span> <span class="n">ProtoAST</span> <span class="o">=</span> <span class="n">ParseExtern</span><span class="p">())</span> <span class="p">{</span>
    <span class="k">if</span> <span class="p">(</span><span class="k">auto</span> <span class="o">*</span><span class="n">FnIR</span> <span class="o">=</span> <span class="n">ProtoAST</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">())</span> <span class="p">{</span>
      <span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;Read extern: &quot;</span><span class="p">);</span>
      <span class="n">FnIR</span><span class="o">-&gt;</span><span class="n">print</span><span class="p">(</span><span class="n">errs</span><span class="p">());</span>
      <span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">);</span>
      <span class="n">FunctionProtos</span><span class="p">[</span><span class="n">ProtoAST</span><span class="o">-&gt;</span><span class="n">getName</span><span class="p">()]</span> <span class="o">=</span> <span class="n">std</span><span class="o">::</span><span class="n">move</span><span class="p">(</span><span class="n">ProtoAST</span><span class="p">);</span>
    <span class="p">}</span>
  <span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
    <span class="c1">// Skip token for error recovery.</span>
    <span class="n">getNextToken</span><span class="p">();</span>
  <span class="p">}</span>
<span class="p">}</span>

<span class="k">static</span> <span class="kt">void</span> <span class="n">HandleTopLevelExpression</span><span class="p">()</span> <span class="p">{</span>
  <span class="c1">// Evaluate a top-level expression into an anonymous function.</span>
  <span class="k">if</span> <span class="p">(</span><span class="k">auto</span> <span class="n">FnAST</span> <span class="o">=</span> <span class="n">ParseTopLevelExpr</span><span class="p">())</span> <span class="p">{</span>
    <span class="n">FnAST</span><span class="o">-&gt;</span><span class="n">codegen</span><span class="p">();</span>
  <span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
    <span class="c1">// Skip token for error recovery.</span>
    <span class="n">getNextToken</span><span class="p">();</span>
  <span class="p">}</span>
<span class="p">}</span>

<span class="c1">/// top ::= definition | external | expression | &#39;;&#39;</span>
<span class="k">static</span> <span class="kt">void</span> <span class="n">MainLoop</span><span class="p">()</span> <span class="p">{</span>
  <span class="k">while</span> <span class="p">(</span><span class="nb">true</span><span class="p">)</span> <span class="p">{</span>
    <span class="k">switch</span> <span class="p">(</span><span class="n">CurTok</span><span class="p">)</span> <span class="p">{</span>
    <span class="k">case</span> <span class="nl">tok_eof</span><span class="p">:</span>
      <span class="k">return</span><span class="p">;</span>
    <span class="k">case</span> <span class="sc">&#39;;&#39;</span><span class="o">:</span> <span class="c1">// ignore top-level semicolons.</span>
      <span class="n">getNextToken</span><span class="p">();</span>
      <span class="k">break</span><span class="p">;</span>
    <span class="k">case</span> <span class="nl">tok_def</span><span class="p">:</span>
      <span class="n">HandleDefinition</span><span class="p">();</span>
      <span class="k">break</span><span class="p">;</span>
    <span class="k">case</span> <span class="nl">tok_extern</span><span class="p">:</span>
      <span class="n">HandleExtern</span><span class="p">();</span>
      <span class="k">break</span><span class="p">;</span>
    <span class="k">default</span><span class="o">:</span>
      <span class="n">HandleTopLevelExpression</span><span class="p">();</span>
      <span class="k">break</span><span class="p">;</span>
    <span class="p">}</span>
  <span class="p">}</span>
<span class="p">}</span>

<span class="c1">//===----------------------------------------------------------------------===//</span>
<span class="c1">// &quot;Library&quot; functions that can be &quot;extern&#39;d&quot; from user code.</span>
<span class="c1">//===----------------------------------------------------------------------===//</span>

<span class="cp">#ifdef _WIN32</span>
<span class="cp">#define DLLEXPORT __declspec(dllexport)</span>
<span class="cp">#else</span>
<span class="cp">#define DLLEXPORT</span>
<span class="cp">#endif</span>

<span class="c1">/// putchard - putchar that takes a double and returns 0.</span>
<span class="k">extern</span> <span class="s">&quot;C&quot;</span> <span class="n">DLLEXPORT</span> <span class="kt">double</span> <span class="n">putchard</span><span class="p">(</span><span class="kt">double</span> <span class="n">X</span><span class="p">)</span> <span class="p">{</span>
  <span class="n">fputc</span><span class="p">((</span><span class="kt">char</span><span class="p">)</span><span class="n">X</span><span class="p">,</span> <span class="n">stderr</span><span class="p">);</span>
  <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>

<span class="c1">/// printd - printf that takes a double prints it as &quot;%f\n&quot;, returning 0.</span>
<span class="k">extern</span> <span class="s">&quot;C&quot;</span> <span class="n">DLLEXPORT</span> <span class="kt">double</span> <span class="n">printd</span><span class="p">(</span><span class="kt">double</span> <span class="n">X</span><span class="p">)</span> <span class="p">{</span>
  <span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;%f</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">,</span> <span class="n">X</span><span class="p">);</span>
  <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>

<span class="c1">//===----------------------------------------------------------------------===//</span>
<span class="c1">// Main driver code.</span>
<span class="c1">//===----------------------------------------------------------------------===//</span>

<span class="kt">int</span> <span class="n">main</span><span class="p">()</span> <span class="p">{</span>
  <span class="c1">// Install standard binary operators.</span>
  <span class="c1">// 1 is lowest precedence.</span>
  <span class="n">BinopPrecedence</span><span class="p">[</span><span class="sc">&#39;&lt;&#39;</span><span class="p">]</span> <span class="o">=</span> <span class="mi">10</span><span class="p">;</span>
  <span class="n">BinopPrecedence</span><span class="p">[</span><span class="sc">&#39;+&#39;</span><span class="p">]</span> <span class="o">=</span> <span class="mi">20</span><span class="p">;</span>
  <span class="n">BinopPrecedence</span><span class="p">[</span><span class="sc">&#39;-&#39;</span><span class="p">]</span> <span class="o">=</span> <span class="mi">20</span><span class="p">;</span>
  <span class="n">BinopPrecedence</span><span class="p">[</span><span class="sc">&#39;*&#39;</span><span class="p">]</span> <span class="o">=</span> <span class="mi">40</span><span class="p">;</span> <span class="c1">// highest.</span>

  <span class="c1">// Prime the first token.</span>
  <span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span> <span class="s">&quot;ready&gt; &quot;</span><span class="p">);</span>
  <span class="n">getNextToken</span><span class="p">();</span>

  <span class="n">InitializeModuleAndPassManager</span><span class="p">();</span>

  <span class="c1">// Run the main &quot;interpreter loop&quot; now.</span>
  <span class="n">MainLoop</span><span class="p">();</span>

  <span class="c1">// Initialize the target registry etc.</span>
  <span class="n">InitializeAllTargetInfos</span><span class="p">();</span>
  <span class="n">InitializeAllTargets</span><span class="p">();</span>
  <span class="n">InitializeAllTargetMCs</span><span class="p">();</span>
  <span class="n">InitializeAllAsmParsers</span><span class="p">();</span>
  <span class="n">InitializeAllAsmPrinters</span><span class="p">();</span>

  <span class="k">auto</span> <span class="n">TargetTriple</span> <span class="o">=</span> <span class="n">sys</span><span class="o">::</span><span class="n">getDefaultTargetTriple</span><span class="p">();</span>
  <span class="n">TheModule</span><span class="o">-&gt;</span><span class="n">setTargetTriple</span><span class="p">(</span><span class="n">TargetTriple</span><span class="p">);</span>

  <span class="n">std</span><span class="o">::</span><span class="n">string</span> <span class="n">Error</span><span class="p">;</span>
  <span class="k">auto</span> <span class="n">Target</span> <span class="o">=</span> <span class="n">TargetRegistry</span><span class="o">::</span><span class="n">lookupTarget</span><span class="p">(</span><span class="n">TargetTriple</span><span class="p">,</span> <span class="n">Error</span><span class="p">);</span>

  <span class="c1">// Print an error and exit if we couldn&#39;t find the requested target.</span>
  <span class="c1">// This generally occurs if we&#39;ve forgotten to initialise the</span>
  <span class="c1">// TargetRegistry or we have a bogus target triple.</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">Target</span><span class="p">)</span> <span class="p">{</span>
    <span class="n">errs</span><span class="p">()</span> <span class="o">&lt;&lt;</span> <span class="n">Error</span><span class="p">;</span>
    <span class="k">return</span> <span class="mi">1</span><span class="p">;</span>
  <span class="p">}</span>

  <span class="k">auto</span> <span class="n">CPU</span> <span class="o">=</span> <span class="s">&quot;generic&quot;</span><span class="p">;</span>
  <span class="k">auto</span> <span class="n">Features</span> <span class="o">=</span> <span class="s">&quot;&quot;</span><span class="p">;</span>

  <span class="n">TargetOptions</span> <span class="n">opt</span><span class="p">;</span>
  <span class="k">auto</span> <span class="n">RM</span> <span class="o">=</span> <span class="n">Optional</span><span class="o">&lt;</span><span class="n">Reloc</span><span class="o">::</span><span class="n">Model</span><span class="o">&gt;</span><span class="p">();</span>
  <span class="k">auto</span> <span class="n">TheTargetMachine</span> <span class="o">=</span>
      <span class="n">Target</span><span class="o">-&gt;</span><span class="n">createTargetMachine</span><span class="p">(</span><span class="n">TargetTriple</span><span class="p">,</span> <span class="n">CPU</span><span class="p">,</span> <span class="n">Features</span><span class="p">,</span> <span class="n">opt</span><span class="p">,</span> <span class="n">RM</span><span class="p">);</span>

  <span class="n">TheModule</span><span class="o">-&gt;</span><span class="n">setDataLayout</span><span class="p">(</span><span class="n">TheTargetMachine</span><span class="o">-&gt;</span><span class="n">createDataLayout</span><span class="p">());</span>

  <span class="k">auto</span> <span class="n">Filename</span> <span class="o">=</span> <span class="s">&quot;output.o&quot;</span><span class="p">;</span>
  <span class="n">std</span><span class="o">::</span><span class="n">error_code</span> <span class="n">EC</span><span class="p">;</span>
  <span class="n">raw_fd_ostream</span> <span class="nf">dest</span><span class="p">(</span><span class="n">Filename</span><span class="p">,</span> <span class="n">EC</span><span class="p">,</span> <span class="n">sys</span><span class="o">::</span><span class="n">fs</span><span class="o">::</span><span class="n">OF_None</span><span class="p">);</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">EC</span><span class="p">)</span> <span class="p">{</span>
    <span class="n">errs</span><span class="p">()</span> <span class="o">&lt;&lt;</span> <span class="s">&quot;Could not open file: &quot;</span> <span class="o">&lt;&lt;</span> <span class="n">EC</span><span class="p">.</span><span class="n">message</span><span class="p">();</span>
    <span class="k">return</span> <span class="mi">1</span><span class="p">;</span>
  <span class="p">}</span>

  <span class="n">legacy</span><span class="o">::</span><span class="n">PassManager</span> <span class="n">pass</span><span class="p">;</span>
  <span class="k">auto</span> <span class="n">FileType</span> <span class="o">=</span> <span class="n">CGFT_ObjectFile</span><span class="p">;</span>

  <span class="k">if</span> <span class="p">(</span><span class="n">TheTargetMachine</span><span class="o">-&gt;</span><span class="n">addPassesToEmitFile</span><span class="p">(</span><span class="n">pass</span><span class="p">,</span> <span class="n">dest</span><span class="p">,</span> <span class="k">nullptr</span><span class="p">,</span> <span class="n">FileType</span><span class="p">))</span> <span class="p">{</span>
    <span class="n">errs</span><span class="p">()</span> <span class="o">&lt;&lt;</span> <span class="s">&quot;TheTargetMachine can&#39;t emit a file of this type&quot;</span><span class="p">;</span>
    <span class="k">return</span> <span class="mi">1</span><span class="p">;</span>
  <span class="p">}</span>

  <span class="n">pass</span><span class="p">.</span><span class="n">run</span><span class="p">(</span><span class="o">*</span><span class="n">TheModule</span><span class="p">);</span>
  <span class="n">dest</span><span class="p">.</span><span class="n">flush</span><span class="p">();</span>

  <span class="n">outs</span><span class="p">()</span> <span class="o">&lt;&lt;</span> <span class="s">&quot;Wrote &quot;</span> <span class="o">&lt;&lt;</span> <span class="n">Filename</span> <span class="o">&lt;&lt;</span> <span class="s">&quot;</span><span class="se">\n</span><span class="s">&quot;</span><span class="p">;</span>

  <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
</pre></div>
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<p><a class="reference external" href="LangImpl09.html">Next: Adding Debug Information</a></p>
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