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  <div class="section" id="building-a-jit-starting-out-with-kaleidoscopejit">
<h1>1. Building a JIT: Starting out with KaleidoscopeJIT<a class="headerlink" href="#building-a-jit-starting-out-with-kaleidoscopejit" title="Permalink to this headline">¶</a></h1>
<div class="contents local topic" id="contents">
<ul class="simple">
<li><a class="reference internal" href="#chapter-1-introduction" id="id9">Chapter 1 Introduction</a></li>
<li><a class="reference internal" href="#jit-api-basics" id="id10">JIT API Basics</a></li>
<li><a class="reference internal" href="#kaleidoscopejit" id="id11">KaleidoscopeJIT</a></li>
<li><a class="reference internal" href="#full-code-listing" id="id12">Full Code Listing</a></li>
</ul>
</div>
<div class="section" id="chapter-1-introduction">
<h2><a class="toc-backref" href="#id9">1.1. Chapter 1 Introduction</a><a class="headerlink" href="#chapter-1-introduction" title="Permalink to this headline">¶</a></h2>
<p><strong>Warning: This tutorial is currently being updated to account for ORC API
changes. Only Chapters 1 and 2 are up-to-date.</strong></p>
<p><strong>Example code from Chapters 3 to 5 will compile and run, but has not been
updated</strong></p>
<p>Welcome to Chapter 1 of the “Building an ORC-based JIT in LLVM” tutorial. This
tutorial runs through the implementation of a JIT compiler using LLVM’s
On-Request-Compilation (ORC) APIs. It begins with a simplified version of the
KaleidoscopeJIT class used in the
<a class="reference external" href="LangImpl01.html">Implementing a language with LLVM</a> tutorials and then
introduces new features like concurrent compilation, optimization, lazy
compilation and remote execution.</p>
<p>The goal of this tutorial is to introduce you to LLVM’s ORC JIT APIs, show how
these APIs interact with other parts of LLVM, and to teach you how to recombine
them to build a custom JIT that is suited to your use-case.</p>
<p>The structure of the tutorial is:</p>
<ul class="simple">
<li>Chapter #1: Investigate the simple KaleidoscopeJIT class. This will
introduce some of the basic concepts of the ORC JIT APIs, including the
idea of an ORC <em>Layer</em>.</li>
<li><a class="reference external" href="BuildingAJIT2.html">Chapter #2</a>: Extend the basic KaleidoscopeJIT by adding
a new layer that will optimize IR and generated code.</li>
<li><a class="reference external" href="BuildingAJIT3.html">Chapter #3</a>: Further extend the JIT by adding a
Compile-On-Demand layer to lazily compile IR.</li>
<li><a class="reference external" href="BuildingAJIT4.html">Chapter #4</a>: Improve the laziness of our JIT by
replacing the Compile-On-Demand layer with a custom layer that uses the ORC
Compile Callbacks API directly to defer IR-generation until functions are
called.</li>
<li><a class="reference external" href="BuildingAJIT5.html">Chapter #5</a>: Add process isolation by JITing code into
a remote process with reduced privileges using the JIT Remote APIs.</li>
</ul>
<p>To provide input for our JIT we will use a lightly modified version of the
Kaleidoscope REPL from <a class="reference external" href="LangImpl07.html">Chapter 7</a> of the “Implementing a
language in LLVM tutorial”.</p>
<p>Finally, a word on API generations: ORC is the 3rd generation of LLVM JIT API.
It was preceded by MCJIT, and before that by the (now deleted) legacy JIT.
These tutorials don’t assume any experience with these earlier APIs, but
readers acquainted with them will see many familiar elements. Where appropriate
we will make this connection with the earlier APIs explicit to help people who
are transitioning from them to ORC.</p>
</div>
<div class="section" id="jit-api-basics">
<h2><a class="toc-backref" href="#id10">1.2. JIT API Basics</a><a class="headerlink" href="#jit-api-basics" title="Permalink to this headline">¶</a></h2>
<p>The purpose of a JIT compiler is to compile code “on-the-fly” as it is needed,
rather than compiling whole programs to disk ahead of time as a traditional
compiler does. To support that aim our initial, bare-bones JIT API will have
just two functions:</p>
<ol class="arabic simple">
<li><code class="docutils literal notranslate"><span class="pre">Error</span> <span class="pre">addModule(std::unique_ptr&lt;Module&gt;</span> <span class="pre">M)</span></code>: Make the given IR module
available for execution.</li>
<li><code class="docutils literal notranslate"><span class="pre">Expected&lt;JITEvaluatedSymbol&gt;</span> <span class="pre">lookup()</span></code>: Search for pointers to
symbols (functions or variables) that have been added to the JIT.</li>
</ol>
<p>A basic use-case for this API, executing the ‘main’ function from a module,
will look like:</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="n">JIT</span> <span class="n">J</span><span class="p">;</span>
<span class="n">J</span><span class="p">.</span><span class="n">addModule</span><span class="p">(</span><span class="n">buildModule</span><span class="p">());</span>
<span class="k">auto</span> <span class="o">*</span><span class="n">Main</span> <span class="o">=</span> <span class="p">(</span><span class="kt">int</span><span class="p">(</span><span class="o">*</span><span class="p">)(</span><span class="kt">int</span><span class="p">,</span> <span class="kt">char</span><span class="o">*</span><span class="p">[]))</span><span class="n">J</span><span class="p">.</span><span class="n">lookup</span><span class="p">(</span><span class="s">&quot;main&quot;</span><span class="p">).</span><span class="n">getAddress</span><span class="p">();</span>
<span class="kt">int</span> <span class="n">Result</span> <span class="o">=</span> <span class="n">Main</span><span class="p">();</span>
</pre></div>
</div>
<p>The APIs that we build in these tutorials will all be variations on this simple
theme. Behind this API we will refine the implementation of the JIT to add
support for concurrent compilation, optimization and lazy compilation.
Eventually we will extend the API itself to allow higher-level program
representations (e.g. ASTs) to be added to the JIT.</p>
</div>
<div class="section" id="kaleidoscopejit">
<h2><a class="toc-backref" href="#id11">1.3. KaleidoscopeJIT</a><a class="headerlink" href="#kaleidoscopejit" title="Permalink to this headline">¶</a></h2>
<p>In the previous section we described our API, now we examine a simple
implementation of it: The KaleidoscopeJIT class <a class="footnote-reference" href="#id6" id="id1">[1]</a> that was used in the
<a class="reference external" href="LangImpl01.html">Implementing a language with LLVM</a> tutorials. We will use
the REPL code from <a class="reference external" href="LangImpl07.html">Chapter 7</a> of that tutorial to supply the
input for our JIT: Each time the user enters an expression the REPL will add a
new IR module containing the code for that expression to the JIT. If the
expression is a top-level expression like ‘1+1’ or ‘sin(x)’, the REPL will also
use the lookup method of our JIT class find and execute the code for the
expression. In later chapters of this tutorial we will modify the REPL to enable
new interactions with our JIT class, but for now we will take this setup for
granted and focus our attention on the implementation of our JIT itself.</p>
<p>Our KaleidoscopeJIT class is defined in the KaleidoscopeJIT.h header. After the
usual include guards and #includes <a class="footnote-reference" href="#id7" id="id4">[2]</a>, we get to the definition of our class:</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#ifndef LLVM_EXECUTIONENGINE_ORC_KALEIDOSCOPEJIT_H</span>
<span class="cp">#define LLVM_EXECUTIONENGINE_ORC_KALEIDOSCOPEJIT_H</span>

<span class="cp">#include</span> <span class="cpf">&quot;llvm/ADT/StringRef.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/JITSymbol.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/Orc/CompileUtils.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/Orc/Core.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/Orc/ExecutionUtils.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/Orc/IRCompileLayer.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/Orc/JITTargetMachineBuilder.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/SectionMemoryManager.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/IR/DataLayout.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">&lt;memory&gt;</span><span class="cp"></span>

<span class="k">namespace</span> <span class="n">llvm</span> <span class="p">{</span>
<span class="k">namespace</span> <span class="n">orc</span> <span class="p">{</span>

<span class="k">class</span> <span class="nc">KaleidoscopeJIT</span> <span class="p">{</span>
<span class="k">private</span><span class="o">:</span>
  <span class="n">ExecutionSession</span> <span class="n">ES</span><span class="p">;</span>
  <span class="n">RTDyldObjectLinkingLayer</span> <span class="n">ObjectLayer</span><span class="p">;</span>
  <span class="n">IRCompileLayer</span> <span class="n">CompileLayer</span><span class="p">;</span>

  <span class="n">DataLayout</span> <span class="n">DL</span><span class="p">;</span>
  <span class="n">MangleAndInterner</span> <span class="n">Mangle</span><span class="p">;</span>
  <span class="n">ThreadSafeContext</span> <span class="n">Ctx</span><span class="p">;</span>

<span class="k">public</span><span class="o">:</span>
  <span class="n">KaleidoscopeJIT</span><span class="p">(</span><span class="n">JITTargetMachineBuilder</span> <span class="n">JTMB</span><span class="p">,</span> <span class="n">DataLayout</span> <span class="n">DL</span><span class="p">)</span>
      <span class="o">:</span> <span class="n">ObjectLayer</span><span class="p">(</span><span class="n">ES</span><span class="p">,</span>
                    <span class="p">[]()</span> <span class="p">{</span> <span class="k">return</span> <span class="n">llvm</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">SectionMemoryManager</span><span class="o">&gt;</span><span class="p">();</span> <span class="p">}),</span>
        <span class="n">CompileLayer</span><span class="p">(</span><span class="n">ES</span><span class="p">,</span> <span class="n">ObjectLayer</span><span class="p">,</span> <span class="n">ConcurrentIRCompiler</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">JTMB</span><span class="p">))),</span>
        <span class="n">DL</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">DL</span><span class="p">)),</span> <span class="n">Mangle</span><span class="p">(</span><span class="n">ES</span><span class="p">,</span> <span class="k">this</span><span class="o">-&gt;</span><span class="n">DL</span><span class="p">),</span>
        <span class="n">Ctx</span><span class="p">(</span><span class="n">llvm</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="p">{</span>
    <span class="n">ES</span><span class="p">.</span><span class="n">getMainJITDylib</span><span class="p">().</span><span class="n">setGenerator</span><span class="p">(</span>
        <span class="n">cantFail</span><span class="p">(</span><span class="n">DynamicLibrarySearchGenerator</span><span class="o">::</span><span class="n">GetForCurrentProcess</span><span class="p">(</span><span class="n">DL</span><span class="p">)));</span>
  <span class="p">}</span>
</pre></div>
</div>
<p>Our class begins with six member variables: An ExecutionSession member, <code class="docutils literal notranslate"><span class="pre">ES</span></code>,
which provides context for our running JIT’d code (including the string pool,
global mutex, and error reporting facilities); An RTDyldObjectLinkingLayer,
<code class="docutils literal notranslate"><span class="pre">ObjectLayer</span></code>, that can be used to add object files to our JIT (though we will
not use it directly); An IRCompileLayer, <code class="docutils literal notranslate"><span class="pre">CompileLayer</span></code>, that can be used to
add LLVM Modules to our JIT (and which builds on the ObjectLayer), A DataLayout
and MangleAndInterner, <code class="docutils literal notranslate"><span class="pre">DL</span></code> and <code class="docutils literal notranslate"><span class="pre">Mangle</span></code>, that will be used for symbol mangling
(more on that later); and finally an LLVMContext that clients will use when
building IR files for the JIT.</p>
<p>Next up we have our class constructor, which takes a <cite>JITTargetMachineBuilder`</cite>
that will be used by our IRCompiler, and a <code class="docutils literal notranslate"><span class="pre">DataLayout</span></code> that we will use to
initialize our DL member. The constructor begins by initializing our
ObjectLayer.  The ObjectLayer requires a reference to the ExecutionSession, and
a function object that will build a JIT memory manager for each module that is
added (a JIT memory manager manages memory allocations, memory permissions, and
registration of exception handlers for JIT’d code). For this we use a lambda
that returns a SectionMemoryManager, an off-the-shelf utility that provides all
the basic memory management functionality required for this chapter. Next we
initialize our CompileLayer. The CompileLayer needs three things: (1) A
reference to the ExecutionSession, (2) A reference to our object layer, and (3)
a compiler instance to use to perform the actual compilation from IR to object
files. We use the off-the-shelf ConcurrentIRCompiler utility as our compiler,
which we construct using this constructor’s JITTargetMachineBuilder argument.
The ConcurrentIRCompiler utility will use the JITTargetMachineBuilder to build
llvm TargetMachines (which are not thread safe) as needed for compiles. After
this, we initialize our supporting members: <code class="docutils literal notranslate"><span class="pre">DL</span></code>, <code class="docutils literal notranslate"><span class="pre">Mangler</span></code> and <code class="docutils literal notranslate"><span class="pre">Ctx</span></code> with
the input DataLayout, the ExecutionSession and DL member, and a new default
constucted LLVMContext respectively. Now that our members have been initialized,
so the one thing that remains to do is to tweak the configuration of the
<em>JITDylib</em> that we will store our code in. We want to modify this dylib to
contain not only the symbols that we add to it, but also the symbols from our
REPL process as well. We do this by attaching a
<code class="docutils literal notranslate"><span class="pre">DynamicLibrarySearchGenerator</span></code> instance using the
<code class="docutils literal notranslate"><span class="pre">DynamicLibrarySearchGenerator::GetForCurrentProcess</span></code> method.</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">static</span> <span class="n">Expected</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">KaleidoscopeJIT</span><span class="o">&gt;&gt;</span> <span class="n">Create</span><span class="p">()</span> <span class="p">{</span>
  <span class="k">auto</span> <span class="n">JTMB</span> <span class="o">=</span> <span class="n">JITTargetMachineBuilder</span><span class="o">::</span><span class="n">detectHost</span><span class="p">();</span>

  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">JTMB</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">JTMB</span><span class="p">.</span><span class="n">takeError</span><span class="p">();</span>

  <span class="k">auto</span> <span class="n">DL</span> <span class="o">=</span> <span class="n">JTMB</span><span class="o">-&gt;</span><span class="n">getDefaultDataLayoutForTarget</span><span class="p">();</span>
  <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">DL</span><span class="p">)</span>
    <span class="k">return</span> <span class="n">DL</span><span class="p">.</span><span class="n">takeError</span><span class="p">();</span>

  <span class="k">return</span> <span class="n">llvm</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">KaleidoscopeJIT</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="o">*</span><span class="n">JTMB</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="o">*</span><span class="n">DL</span><span class="p">));</span>
<span class="p">}</span>

<span class="k">const</span> <span class="n">DataLayout</span> <span class="o">&amp;</span><span class="n">getDataLayout</span><span class="p">()</span> <span class="k">const</span> <span class="p">{</span> <span class="k">return</span> <span class="n">DL</span><span class="p">;</span> <span class="p">}</span>

<span class="n">LLVMContext</span> <span class="o">&amp;</span><span class="n">getContext</span><span class="p">()</span> <span class="p">{</span> <span class="k">return</span> <span class="o">*</span><span class="n">Ctx</span><span class="p">.</span><span class="n">getContext</span><span class="p">();</span> <span class="p">}</span>
</pre></div>
</div>
<p>Next we have a named constructor, <code class="docutils literal notranslate"><span class="pre">Create</span></code>, which will build a KaleidoscopeJIT
instance that is configured to generate code for our host process. It does this
by first generating a JITTargetMachineBuilder instance using that clases’s
detectHost method and then using that instance to generate a datalayout for
the target process. Each of these operations can fail, so each returns its
result wrapped in an Expected value <a class="footnote-reference" href="#id8" id="id5">[3]</a> that we must check for error before
continuing. If both operations succeed we can unwrap their results (using the
dereference operator) and pass them into KaleidoscopeJIT’s constructor on the
last line of the function.</p>
<p>Following the named constructor we have the <code class="docutils literal notranslate"><span class="pre">getDataLayout()</span></code> and
<code class="docutils literal notranslate"><span class="pre">getContext()</span></code> methods. These are used to make data structures created and
managed by the JIT (especially the LLVMContext) available to the REPL code that
will build our IR modules.</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="kt">void</span> <span class="nf">addModule</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">Module</span><span class="o">&gt;</span> <span class="n">M</span><span class="p">)</span> <span class="p">{</span>
  <span class="n">cantFail</span><span class="p">(</span><span class="n">CompileLayer</span><span class="p">.</span><span class="n">add</span><span class="p">(</span><span class="n">ES</span><span class="p">.</span><span class="n">getMainJITDylib</span><span class="p">(),</span>
                            <span class="n">ThreadSafeModule</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">M</span><span class="p">),</span> <span class="n">Ctx</span><span class="p">)));</span>
<span class="p">}</span>

<span class="n">Expected</span><span class="o">&lt;</span><span class="n">JITEvaluatedSymbol</span><span class="o">&gt;</span> <span class="n">lookup</span><span class="p">(</span><span class="n">StringRef</span> <span class="n">Name</span><span class="p">)</span> <span class="p">{</span>
  <span class="k">return</span> <span class="n">ES</span><span class="p">.</span><span class="n">lookup</span><span class="p">({</span><span class="o">&amp;</span><span class="n">ES</span><span class="p">.</span><span class="n">getMainJITDylib</span><span class="p">()},</span> <span class="n">Mangle</span><span class="p">(</span><span class="n">Name</span><span class="p">.</span><span class="n">str</span><span class="p">()));</span>
<span class="p">}</span>
</pre></div>
</div>
<p>Now we come to the first of our JIT API methods: addModule. This method is
responsible for adding IR to the JIT and making it available for execution. In
this initial implementation of our JIT we will make our modules “available for
execution” by adding them to the CompileLayer, which will it turn store the
Module in the main JITDylib. This process will create new symbol table entries
in the JITDylib for each definition in the module, and will defer compilation of
the module until any of its definitions is looked up. Note that this is not lazy
compilation: just referencing a definition, even if it is never used, will be
enough to trigger compilation. In later chapters we will teach our JIT to defer
compilation of functions until they’re actually called.  To add our Module we
must first wrap it in a ThreadSafeModule instance, which manages the lifetime of
the Module’s LLVMContext (our Ctx member) in a thread-friendly way. In our
example, all modules will share the Ctx member, which will exist for the
duration of the JIT. Once we switch to concurrent compilation in later chapters
we will use a new context per module.</p>
<p>Our last method is <code class="docutils literal notranslate"><span class="pre">lookup</span></code>, which allows us to look up addresses for
function and variable definitions added to the JIT based on their symbol names.
As noted above, lookup will implicitly trigger compilation for any symbol
that has not already been compiled. Our lookup method calls through to
<cite>ExecutionSession::lookup</cite>, passing in a list of dylibs to search (in our case
just the main dylib), and the symbol name to search for, with a twist: We have
to <em>mangle</em> the name of the symbol we’re searching for first. The ORC JIT
components use mangled symbols internally the same way a static compiler and
linker would, rather than using plain IR symbol names. This allows JIT’d code
to interoperate easily with precompiled code in the application or shared
libraries. The kind of mangling will depend on the DataLayout, which in turn
depends on the target platform. To allow us to remain portable and search based
on the un-mangled name, we just re-produce this mangling ourselves using our
<code class="docutils literal notranslate"><span class="pre">Mangle</span></code> member function object.</p>
<p>This brings us to the end of Chapter 1 of Building a JIT. You now have a basic
but fully functioning JIT stack that you can use to take LLVM IR and make it
executable within the context of your JIT process. In the next chapter we’ll
look at how to extend this JIT to produce better quality code, and in the
process take a deeper look at the ORC layer concept.</p>
<p><a class="reference external" href="BuildingAJIT2.html">Next: Extending the KaleidoscopeJIT</a></p>
</div>
<div class="section" id="full-code-listing">
<h2><a class="toc-backref" href="#id12">1.4. Full Code Listing</a><a class="headerlink" href="#full-code-listing" title="Permalink to this headline">¶</a></h2>
<p>Here is the complete code listing for our running example. To build this
example, use:</p>
<div class="highlight-bash notranslate"><div class="highlight"><pre><span></span><span class="c1"># Compile</span>
clang++ -g toy.cpp <span class="sb">`</span>llvm-config --cxxflags --ldflags --system-libs --libs core orcjit native<span class="sb">`</span> -O3 -o toy
<span class="c1"># Run</span>
./toy
</pre></div>
</div>
<p>Here is the code:</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="c1">//===- KaleidoscopeJIT.h - A simple JIT for Kaleidoscope --------*- C++ -*-===//</span>
<span class="c1">//</span>
<span class="c1">//                     The LLVM Compiler Infrastructure</span>
<span class="c1">//</span>
<span class="c1">// This file is distributed under the University of Illinois Open Source</span>
<span class="c1">// License. See LICENSE.TXT for details.</span>
<span class="c1">//</span>
<span class="c1">//===----------------------------------------------------------------------===//</span>
<span class="c1">//</span>
<span class="c1">// Contains a simple JIT definition for use in the kaleidoscope tutorials.</span>
<span class="c1">//</span>
<span class="c1">//===----------------------------------------------------------------------===//</span>

<span class="cp">#ifndef LLVM_EXECUTIONENGINE_ORC_KALEIDOSCOPEJIT_H</span>
<span class="cp">#define LLVM_EXECUTIONENGINE_ORC_KALEIDOSCOPEJIT_H</span>

<span class="cp">#include</span> <span class="cpf">&quot;llvm/ADT/StringRef.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/JITSymbol.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/Orc/CompileUtils.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/Orc/Core.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/Orc/ExecutionUtils.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/Orc/IRCompileLayer.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/Orc/JITTargetMachineBuilder.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/ExecutionEngine/SectionMemoryManager.h&quot;</span><span class="cp"></span>
<span class="cp">#include</span> <span class="cpf">&quot;llvm/IR/DataLayout.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">&lt;memory&gt;</span><span class="cp"></span>

<span class="k">namespace</span> <span class="n">llvm</span> <span class="p">{</span>
<span class="k">namespace</span> <span class="n">orc</span> <span class="p">{</span>

<span class="k">class</span> <span class="nc">KaleidoscopeJIT</span> <span class="p">{</span>
<span class="k">private</span><span class="o">:</span>
  <span class="n">ExecutionSession</span> <span class="n">ES</span><span class="p">;</span>
  <span class="n">RTDyldObjectLinkingLayer</span> <span class="n">ObjectLayer</span><span class="p">;</span>
  <span class="n">IRCompileLayer</span> <span class="n">CompileLayer</span><span class="p">;</span>

  <span class="n">DataLayout</span> <span class="n">DL</span><span class="p">;</span>
  <span class="n">MangleAndInterner</span> <span class="n">Mangle</span><span class="p">;</span>
  <span class="n">ThreadSafeContext</span> <span class="n">Ctx</span><span class="p">;</span>

<span class="k">public</span><span class="o">:</span>
  <span class="n">KaleidoscopeJIT</span><span class="p">(</span><span class="n">JITTargetMachineBuilder</span> <span class="n">JTMB</span><span class="p">,</span> <span class="n">DataLayout</span> <span class="n">DL</span><span class="p">)</span>
      <span class="o">:</span> <span class="n">ObjectLayer</span><span class="p">(</span><span class="n">ES</span><span class="p">,</span>
                    <span class="p">[]()</span> <span class="p">{</span> <span class="k">return</span> <span class="n">llvm</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">SectionMemoryManager</span><span class="o">&gt;</span><span class="p">();</span> <span class="p">}),</span>
        <span class="n">CompileLayer</span><span class="p">(</span><span class="n">ES</span><span class="p">,</span> <span class="n">ObjectLayer</span><span class="p">,</span> <span class="n">ConcurrentIRCompiler</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">JTMB</span><span class="p">))),</span>
        <span class="n">DL</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">DL</span><span class="p">)),</span> <span class="n">Mangle</span><span class="p">(</span><span class="n">ES</span><span class="p">,</span> <span class="k">this</span><span class="o">-&gt;</span><span class="n">DL</span><span class="p">),</span>
        <span class="n">Ctx</span><span class="p">(</span><span class="n">llvm</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="p">{</span>
    <span class="n">ES</span><span class="p">.</span><span class="n">getMainJITDylib</span><span class="p">().</span><span class="n">setGenerator</span><span class="p">(</span>
        <span class="n">cantFail</span><span class="p">(</span><span class="n">DynamicLibrarySearchGenerator</span><span class="o">::</span><span class="n">GetForCurrentProcess</span><span class="p">(</span><span class="n">DL</span><span class="p">)));</span>
  <span class="p">}</span>

  <span class="k">static</span> <span class="n">Expected</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">KaleidoscopeJIT</span><span class="o">&gt;&gt;</span> <span class="n">Create</span><span class="p">()</span> <span class="p">{</span>
    <span class="k">auto</span> <span class="n">JTMB</span> <span class="o">=</span> <span class="n">JITTargetMachineBuilder</span><span class="o">::</span><span class="n">detectHost</span><span class="p">();</span>

    <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">JTMB</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">JTMB</span><span class="p">.</span><span class="n">takeError</span><span class="p">();</span>

    <span class="k">auto</span> <span class="n">DL</span> <span class="o">=</span> <span class="n">JTMB</span><span class="o">-&gt;</span><span class="n">getDefaultDataLayoutForTarget</span><span class="p">();</span>
    <span class="k">if</span> <span class="p">(</span><span class="o">!</span><span class="n">DL</span><span class="p">)</span>
      <span class="k">return</span> <span class="n">DL</span><span class="p">.</span><span class="n">takeError</span><span class="p">();</span>

    <span class="k">return</span> <span class="n">llvm</span><span class="o">::</span><span class="n">make_unique</span><span class="o">&lt;</span><span class="n">KaleidoscopeJIT</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="o">*</span><span class="n">JTMB</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="o">*</span><span class="n">DL</span><span class="p">));</span>
  <span class="p">}</span>

  <span class="k">const</span> <span class="n">DataLayout</span> <span class="o">&amp;</span><span class="n">getDataLayout</span><span class="p">()</span> <span class="k">const</span> <span class="p">{</span> <span class="k">return</span> <span class="n">DL</span><span class="p">;</span> <span class="p">}</span>

  <span class="n">LLVMContext</span> <span class="o">&amp;</span><span class="n">getContext</span><span class="p">()</span> <span class="p">{</span> <span class="k">return</span> <span class="o">*</span><span class="n">Ctx</span><span class="p">.</span><span class="n">getContext</span><span class="p">();</span> <span class="p">}</span>

  <span class="n">Error</span> <span class="n">addModule</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">Module</span><span class="o">&gt;</span> <span class="n">M</span><span class="p">)</span> <span class="p">{</span>
    <span class="k">return</span> <span class="n">CompileLayer</span><span class="p">.</span><span class="n">add</span><span class="p">(</span><span class="n">ES</span><span class="p">.</span><span class="n">getMainJITDylib</span><span class="p">(),</span>
                            <span class="n">ThreadSafeModule</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">M</span><span class="p">),</span> <span class="n">Ctx</span><span class="p">));</span>
  <span class="p">}</span>

  <span class="n">Expected</span><span class="o">&lt;</span><span class="n">JITEvaluatedSymbol</span><span class="o">&gt;</span> <span class="n">lookup</span><span class="p">(</span><span class="n">StringRef</span> <span class="n">Name</span><span class="p">)</span> <span class="p">{</span>
    <span class="k">return</span> <span class="n">ES</span><span class="p">.</span><span class="n">lookup</span><span class="p">({</span><span class="o">&amp;</span><span class="n">ES</span><span class="p">.</span><span class="n">getMainJITDylib</span><span class="p">()},</span> <span class="n">Mangle</span><span class="p">(</span><span class="n">Name</span><span class="p">.</span><span class="n">str</span><span class="p">()));</span>
  <span class="p">}</span>
<span class="p">};</span>

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

<span class="cp">#endif </span><span class="c1">// LLVM_EXECUTIONENGINE_ORC_KALEIDOSCOPEJIT_H</span>
</pre></div>
</div>
<table class="docutils footnote" frame="void" id="id6" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#id1">[1]</a></td><td>Actually we use a cut-down version of KaleidoscopeJIT that makes a
simplifying assumption: symbols cannot be re-defined. This will make it
impossible to re-define symbols in the REPL, but will make our symbol
lookup logic simpler. Re-introducing support for symbol redefinition is
left as an exercise for the reader. (The KaleidoscopeJIT.h used in the
original tutorials will be a helpful reference).</td></tr>
</tbody>
</table>
<table class="docutils footnote" frame="void" id="id7" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#id4">[2]</a></td><td><table border="1" class="first last docutils">
<colgroup>
<col width="38%" />
<col width="62%" />
</colgroup>
<thead valign="bottom">
<tr class="row-odd"><th class="head">File</th>
<th class="head">Reason for inclusion</th>
</tr>
</thead>
<tbody valign="top">
<tr class="row-even"><td>JITSymbol.h</td>
<td>Defines the lookup result type
JITEvaluatedSymbol</td>
</tr>
<tr class="row-odd"><td>CompileUtils.h</td>
<td>Provides the SimpleCompiler class.</td>
</tr>
<tr class="row-even"><td>Core.h</td>
<td>Core utilities such as ExecutionSession and
JITDylib.</td>
</tr>
<tr class="row-odd"><td>ExecutionUtils.h</td>
<td>Provides the DynamicLibrarySearchGenerator
class.</td>
</tr>
<tr class="row-even"><td>IRCompileLayer.h</td>
<td>Provides the IRCompileLayer class.</td>
</tr>
<tr class="row-odd"><td>JITTargetMachineBuilder.h</td>
<td>Provides the JITTargetMachineBuilder class.</td>
</tr>
<tr class="row-even"><td>RTDyldObjectLinkingLayer.h</td>
<td>Provides the RTDyldObjectLinkingLayer class.</td>
</tr>
<tr class="row-odd"><td>SectionMemoryManager.h</td>
<td>Provides the SectionMemoryManager class.</td>
</tr>
<tr class="row-even"><td>DataLayout.h</td>
<td>Provides the DataLayout class.</td>
</tr>
<tr class="row-odd"><td>LLVMContext.h</td>
<td>Provides the LLVMContext class.</td>
</tr>
</tbody>
</table>
</td></tr>
</tbody>
</table>
<table class="docutils footnote" frame="void" id="id8" rules="none">
<colgroup><col class="label" /><col /></colgroup>
<tbody valign="top">
<tr><td class="label"><a class="fn-backref" href="#id5">[3]</a></td><td>See the ErrorHandling section in the LLVM Programmer’s Manual
(<a class="reference external" href="http://llvm.org/docs/ProgrammersManual.html#error-handling">http://llvm.org/docs/ProgrammersManual.html#error-handling</a>)</td></tr>
</tbody>
</table>
</div>
</div>


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