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. 15 Please do not edit directly! 16 The 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 (a] 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 31 more adaptable and easier to customize. Most of LLVMC functionality is 32 implemented via high-level TableGen code, from which a corresponding C++ source 33 file is automatically generated. This tutorial describes the basic usage and 34 configuration 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 39 as possible, so most of the familiar options work:</p> 40 <pre class="literal-block"> 41 $ llvmc -O3 -Wall hello.cpp 42 $ ./a.out 43 hello 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 46 executed by using the <tt class="docutils literal"><span class="pre">-v</span></tt> option). For further help on command-line LLVMC 47 usage, 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 52 familiar 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> 60 int main() { printf("Hello\n"); } 61 $ $LLVM_BIN_DIR/Simple -v hello.c 62 gcc hello.c -o hello.out 63 $ ./hello.out 64 Hello 65 </pre> 66 <p>We have thus produced a simple driver called, appropriately, <tt class="docutils literal">Simple</tt>, from 67 the input TableGen file <tt class="docutils literal">Simple.td</tt>. The <tt class="docutils literal">llvmc</tt> program itself is generated 68 using a similar process (see <tt class="docutils literal">llvmc/src</tt>). Contents of the file <tt class="docutils literal">Simple.td</tt> 69 look like this:</p> 70 <pre class="literal-block"> 71 // Include common definitions 72 include "llvm/CompilerDriver/Common.td" 73 74 // Tool descriptions 75 def 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 88 def LanguageMap : LanguageMap<[(lang_to_suffixes "c", "c")]>; 89 90 // Compilation graph 91 def CompilationGraph : CompilationGraph<[(edge "root", "gcc")]>; 92 </pre> 93 <p>As you can see, this file consists of three parts: tool descriptions, language 94 map, and the compilation graph definition.</p> 95 <p>At the heart of LLVMC is the idea of a compilation graph: vertices in this graph 96 are tools, and edges represent a transformation path between two tools (for 97 example, assembly source produced by the compiler can be transformed into 98 executable code by an assembler). The compilation graph is basically a list of 99 edges; 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 101 example above should be self-explanatory; the <tt class="docutils literal">sink</tt> property means that all 102 options 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 104 used 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 106 manual and examples in the <tt class="docutils literal">examples</tt> directory. Of a particular interest is 107 the <tt class="docutils literal">Skeleton</tt> example, which can serve as a template for your LLVMC-based 108 drivers.</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 (a] codedgers.com">Mikhail Glushenkov</a><br /> 119 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br /> 120 121 Last modified: $Date: 2008-12-11 11:34:48 -0600 (Thu, 11 Dec 2008) $ 122 </address></div> 123 </div> 124 </body> 125 </html> 126
