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Mikhail Glushenkov99a3a2c2008-12-11 23:33:33 +0000[diff] [blame]7<title>Tutorial - Using LLVMC</title>
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]8<link rel="stylesheet" href="llvm-rst.css" type="text/css" />
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Mikhail Glushenkov99a3a2c2008-12-11 23:33:33 +0000[diff] [blame]11<div class="document" id="tutorial-using-llvmc">
12<h1 class="title">Tutorial - Using LLVMC</h1>
Mikhail Glushenkovd5652032008-12-13 02:28:58 +0000[diff] [blame^]13<div class="contents topic">
14<p class="topic-title first"><a id="contents" name="contents">Contents</a></p>
15<ul class="simple">
16<li><a class="reference" href="#introduction" id="id1" name="id1">Introduction</a></li>
17<li><a class="reference" href="#compiling-with-llvmc" id="id2" name="id2">Compiling with LLVMC</a></li>
18<li><a class="reference" href="#using-llvmc-to-generate-toolchain-drivers" id="id3" name="id3">Using LLVMC to generate toolchain drivers</a></li>
19</ul>
20</div>
21<div class="doc_author">
22<p>Written by <a href="mailto:foldr@codedgers.com">Mikhail Glushenkov</a></p>
23</div><div class="section">
24<h1><a class="toc-backref" href="#id1" id="introduction" name="introduction">Introduction</a></h1>
Mikhail Glushenkov99a3a2c2008-12-11 23:33:33 +0000[diff] [blame]25<p>LLVMC is a generic compiler driver, which plays the same role for LLVM
26as the <tt class="docutils literal"><span class="pre">gcc</span></tt> program does for GCC - the difference being that LLVMC
27is designed to be more adaptable and easier to customize. Most of
28LLVMC functionality is implemented via plugins, which can be loaded
29dynamically or compiled in. This tutorial describes the basic usage
30and configuration of LLVMC.</p>
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]31</div>
32<div class="section">
Mikhail Glushenkovd5652032008-12-13 02:28:58 +0000[diff] [blame^]33<h1><a class="toc-backref" href="#id2" id="compiling-with-llvmc" name="compiling-with-llvmc">Compiling with LLVMC</a></h1>
Mikhail Glushenkov99a3a2c2008-12-11 23:33:33 +0000[diff] [blame]34<p>In general, LLVMC tries to be command-line compatible with <tt class="docutils literal"><span class="pre">gcc</span></tt> as
35much as possible, so most of the familiar options work:</p>
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]36<pre class="literal-block">
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]37$ llvmc -O3 -Wall hello.cpp
38$ ./a.out
39hello
40</pre>
Mikhail Glushenkov99a3a2c2008-12-11 23:33:33 +0000[diff] [blame]41<p>This will invoke <tt class="docutils literal"><span class="pre">llvm-g++</span></tt> under the hood (you can see which
42commands are executed by using the <tt class="docutils literal"><span class="pre">-v</span></tt> option). For further help on
43command-line LLVMC usage, refer to the <tt class="docutils literal"><span class="pre">llvmc</span> <span class="pre">--help</span></tt> output.</p>
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]44</div>
45<div class="section">
Mikhail Glushenkovd5652032008-12-13 02:28:58 +0000[diff] [blame^]46<h1><a class="toc-backref" href="#id3" id="using-llvmc-to-generate-toolchain-drivers" name="using-llvmc-to-generate-toolchain-drivers">Using LLVMC to generate toolchain drivers</a></h1>
47<p>LLVMC plugins are written mostly using <a class="reference" href="http://llvm.cs.uiuc.edu/docs/TableGenFundamentals.html">TableGen</a>, so you need to
Mikhail Glushenkov99a3a2c2008-12-11 23:33:33 +0000[diff] [blame]48be familiar with it to get anything done.</p>
49<p>Start by compiling <tt class="docutils literal"><span class="pre">plugins/Simple/Simple.td</span></tt>, which is a primitive
50wrapper for <tt class="docutils literal"><span class="pre">gcc</span></tt>:</p>
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]51<pre class="literal-block">
Mikhail Glushenkov99a3a2c2008-12-11 23:33:33 +0000[diff] [blame]52$ cd $LLVM_DIR/tools/llvmc
53$ make DRIVER_NAME=mygcc BUILTIN_PLUGINS=Simple
54$ cat &gt; hello.c
55[...]
56$ mygcc hello.c
57$ ./hello.out
58Hello
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]59</pre>
Mikhail Glushenkov99a3a2c2008-12-11 23:33:33 +0000[diff] [blame]60<p>Here we link our plugin with the LLVMC core statically to form an
61executable file called <tt class="docutils literal"><span class="pre">mygcc</span></tt>. It is also possible to build our
62plugin as a standalone dynamic library; this is described in the
63reference manual.</p>
64<p>Contents of the file <tt class="docutils literal"><span class="pre">Simple.td</span></tt> look like this:</p>
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]65<pre class="literal-block">
Mikhail Glushenkov99a3a2c2008-12-11 23:33:33 +0000[diff] [blame]66// Include common definitions
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]67include &quot;llvm/CompilerDriver/Common.td&quot;
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]68
Mikhail Glushenkov99a3a2c2008-12-11 23:33:33 +0000[diff] [blame]69// Tool descriptions
70def gcc : Tool&lt;
71[(in_language &quot;c&quot;),
72 (out_language &quot;executable&quot;),
73 (output_suffix &quot;out&quot;),
74 (cmd_line &quot;gcc $INFILE -o $OUTFILE&quot;),
75 (sink)
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]76]&gt;;
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]77
Mikhail Glushenkov99a3a2c2008-12-11 23:33:33 +0000[diff] [blame]78// Language map
79def LanguageMap : LanguageMap&lt;[LangToSuffixes&lt;&quot;c&quot;, [&quot;c&quot;]&gt;]&gt;;
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]80
Mikhail Glushenkov99a3a2c2008-12-11 23:33:33 +0000[diff] [blame]81// Compilation graph
82def CompilationGraph : CompilationGraph&lt;[Edge&lt;&quot;root&quot;, &quot;gcc&quot;&gt;]&gt;;
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]83</pre>
Mikhail Glushenkov99a3a2c2008-12-11 23:33:33 +0000[diff] [blame]84<p>As you can see, this file consists of three parts: tool descriptions,
85language map, and the compilation graph definition.</p>
86<p>At the heart of LLVMC is the idea of a compilation graph: vertices in
87this graph are tools, and edges represent a transformation path
88between two tools (for example, assembly source produced by the
89compiler can be transformed into executable code by an assembler). The
90compilation graph is basically a list of edges; a special node named
91<tt class="docutils literal"><span class="pre">root</span></tt> is used to mark graph entry points.</p>
92<p>Tool descriptions are represented as property lists: most properties
93in the example above should be self-explanatory; the <tt class="docutils literal"><span class="pre">sink</span></tt> property
94means that all options lacking an explicit description should be
95forwarded to this tool.</p>
96<p>The <tt class="docutils literal"><span class="pre">LanguageMap</span></tt> associates a language name with a list of suffixes
97and is used for deciding which toolchain corresponds to a given input
98file.</p>
99<p>To learn more about LLVMC customization, refer to the reference
100manual and plugin source code in the <tt class="docutils literal"><span class="pre">plugins</span></tt> directory.</p>
Mikhail Glushenkov90531542008-12-11 23:43:14 +0000[diff] [blame]101<hr />
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]102<address>
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Mikhail Glushenkovd5652032008-12-13 02:28:58 +0000[diff] [blame^]110<a href="mailto:foldr@codedgers.com">Mikhail Glushenkov</a><br />
111<a href="http://llvm.org">LLVM Compiler Infrastructure</a><br />
Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]112
Mikhail Glushenkovd5652032008-12-13 02:28:58 +0000[diff] [blame^]113Last modified: $Date: 2008-12-11 11:34:48 -0600 (Thu, 11 Dec 2008) $
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Mikhail Glushenkov68319f82008-12-11 23:24:40 +0000[diff] [blame]115</div>
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