1<?xml version="1.0" encoding="utf-8" ?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> 4<head> 5<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 6<meta name="generator" content="Docutils 0.6: http://docutils.sourceforge.net/" /> 7<title>Tutorial - Using LLVMC</title> 8<link rel="stylesheet" href="llvm.css" type="text/css" /> 9</head> 10<body> 11<div class="document" id="tutorial-using-llvmc"> 12<h1 class="title">Tutorial - Using LLVMC</h1> 13 14<!-- This file was automatically generated by rst2html. 15Please do not edit directly! 16The ReST source lives in the directory 'tools/llvmc/doc'. --> 17<div class="contents topic" id="contents"> 18<p class="topic-title first">Contents</p> 19<ul class="simple"> 20<li><a class="reference internal" href="#introduction" id="id1">Introduction</a></li> 21<li><a class="reference internal" href="#using-the-llvmc-program" id="id2">Using the <tt class="docutils literal">llvmc</tt> program</a></li> 22<li><a class="reference internal" href="#using-llvmc-to-generate-toolchain-drivers" id="id3">Using LLVMC to generate toolchain drivers</a></li> 23</ul> 24</div> 25<div class="doc_author"> 26<p>Written by <a href="mailto:foldr@codedgers.com">Mikhail Glushenkov</a></p> 27</div><div class="section" id="introduction"> 28<h1><a class="toc-backref" href="#id1">Introduction</a></h1> 29<p>LLVMC is a generic compiler driver, which plays the same role for LLVM as the 30<tt class="docutils literal">gcc</tt> program does for GCC - the difference being that LLVMC is designed to be 31more adaptable and easier to customize. Most of LLVMC functionality is 32implemented via high-level TableGen code, from which a corresponding C++ source 33file is automatically generated. This tutorial describes the basic usage and 34configuration of LLVMC.</p> 35</div> 36<div class="section" id="using-the-llvmc-program"> 37<h1><a class="toc-backref" href="#id2">Using the <tt class="docutils literal">llvmc</tt> program</a></h1> 38<p>In general, <tt class="docutils literal">llvmc</tt> tries to be command-line compatible with <tt class="docutils literal">gcc</tt> as much 39as possible, so most of the familiar options work:</p> 40<pre class="literal-block"> 41$ llvmc -O3 -Wall hello.cpp 42$ ./a.out 43hello 44</pre> 45<p>This will invoke <tt class="docutils literal"><span class="pre">llvm-g++</span></tt> under the hood (you can see which commands are 46executed by using the <tt class="docutils literal"><span class="pre">-v</span></tt> option). For further help on command-line LLVMC 47usage, refer to the <tt class="docutils literal">llvmc <span class="pre">--help</span></tt> output.</p> 48</div> 49<div class="section" id="using-llvmc-to-generate-toolchain-drivers"> 50<h1><a class="toc-backref" href="#id3">Using LLVMC to generate toolchain drivers</a></h1> 51<p>LLVMC-based drivers are written mostly using <a class="reference external" href="http://llvm.org/docs/TableGenFundamentals.html">TableGen</a>, so you need to be 52familiar with it to get anything done.</p> 53<p>Start by compiling <tt class="docutils literal">example/Simple</tt>, which is a primitive wrapper for 54<tt class="docutils literal">gcc</tt>:</p> 55<pre class="literal-block"> 56$ cd $LLVM_OBJ_DIR/tools/examples/Simple 57$ make 58$ cat > hello.c 59#include <stdio.h> 60int main() { printf("Hello\n"); } 61$ $LLVM_BIN_DIR/Simple -v hello.c 62gcc hello.c -o hello.out 63$ ./hello.out 64Hello 65</pre> 66<p>We have thus produced a simple driver called, appropriately, <tt class="docutils literal">Simple</tt>, from 67the input TableGen file <tt class="docutils literal">Simple.td</tt>. The <tt class="docutils literal">llvmc</tt> program itself is generated 68using a similar process (see <tt class="docutils literal">llvmc/src</tt>). Contents of the file <tt class="docutils literal">Simple.td</tt> 69look like this:</p> 70<pre class="literal-block"> 71// Include common definitions 72include "llvm/CompilerDriver/Common.td" 73 74// Tool descriptions 75def gcc : Tool< 76[(in_language "c"), 77 (out_language "executable"), 78 (output_suffix "out"), 79 (command "gcc"), 80 (sink), 81 82 // -o is what is used by default, out_file_option here is included for 83 // instructive purposes. 84 (out_file_option "-o") 85]>; 86 87// Language map 88def LanguageMap : LanguageMap<[(lang_to_suffixes "c", "c")]>; 89 90// Compilation graph 91def CompilationGraph : CompilationGraph<[(edge "root", "gcc")]>; 92</pre> 93<p>As you can see, this file consists of three parts: tool descriptions, language 94map, and the compilation graph definition.</p> 95<p>At the heart of LLVMC is the idea of a compilation graph: vertices in this graph 96are tools, and edges represent a transformation path between two tools (for 97example, assembly source produced by the compiler can be transformed into 98executable code by an assembler). The compilation graph is basically a list of 99edges; a special node named <tt class="docutils literal">root</tt> is used to mark graph entry points.</p> 100<p>Tool descriptions are represented as property lists: most properties in the 101example above should be self-explanatory; the <tt class="docutils literal">sink</tt> property means that all 102options lacking an explicit description should be forwarded to this tool.</p> 103<p>The <tt class="docutils literal">LanguageMap</tt> associates a language name with a list of suffixes and is 104used for deciding which toolchain corresponds to a given input file.</p> 105<p>To learn more about writing your own drivers with LLVMC, refer to the reference 106manual and examples in the <tt class="docutils literal">examples</tt> directory. Of a particular interest is 107the <tt class="docutils literal">Skeleton</tt> example, which can serve as a template for your LLVMC-based 108drivers.</p> 109<hr /> 110<address> 111<a href="http://jigsaw.w3.org/css-validator/check/referer"> 112<img src="http://jigsaw.w3.org/css-validator/images/vcss-blue" 113 alt="Valid CSS" /></a> 114<a href="http://validator.w3.org/check?uri=referer"> 115<img src="http://www.w3.org/Icons/valid-xhtml10-blue" 116 alt="Valid XHTML 1.0 Transitional"/></a> 117 118<a href="mailto:foldr@codedgers.com">Mikhail Glushenkov</a><br /> 119<a href="http://llvm.org">LLVM Compiler Infrastructure</a><br /> 120 121Last modified: $Date: 2008-12-11 11:34:48 -0600 (Thu, 11 Dec 2008) $ 122</address></div> 123</div> 124</body> 125</html> 126