1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" 2 "http://www.w3.org/TR/html4/strict.dtd"> 3 <html> 4 <head> 5 <META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 6 <title>Clang - Getting Started</title> 7 <link type="text/css" rel="stylesheet" href="menu.css"> 8 <link type="text/css" rel="stylesheet" href="content.css"> 9 </head> 10 <body> 11 12 <!--#include virtual="menu.html.incl"--> 13 14 <div id="content"> 15 16 <h1>Getting Started: Building and Running Clang</h1> 17 18 <p>This page gives you the shortest path to checking out Clang and demos a few 19 options. This should get you up and running with the minimum of muss and fuss. 20 If you like what you see, please consider <a href="get_involved.html">getting 21 involved</a> with the Clang community. If you run into problems, please file 22 bugs in <a href="http://llvm.org/bugs/">LLVM Bugzilla</a>.</p> 23 24 <h2 id="download">Release Clang Versions</h2> 25 26 <p>Clang is released as part of regular LLVM releases. You can download the release versions from <a href="http://llvm.org/releases/">http://llvm.org/releases/</a>.</p> 27 <p>Clang is also provided in all major BSD or GNU/Linux distributions as part of their respective packaging systems. From Xcode 4.2, Clang is the default compiler for Mac OS X.</p> 28 29 <h2 id="build">Building Clang and Working with the Code</h2> 30 31 <h3 id="buildNix">On Unix-like Systems</h3> 32 33 <p>If you would like to check out and build Clang, the current procedure is as 34 follows:</p> 35 36 <ol> 37 <li>Get the required tools. 38 <ul> 39 <li>See 40 <a href="http://llvm.org/docs/GettingStarted.html#requirements"> 41 Getting Started with the LLVM System - Requirements</a>.</li> 42 <li>Note also that Python is needed for running the test suite. 43 Get it at: <a href="http://www.python.org/download"> 44 http://www.python.org/download</a></li> 45 </ul> 46 47 <li>Checkout LLVM: 48 <ul> 49 <li>Change directory to where you want the llvm directory placed.</li> 50 <li><tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li> 51 </ul> 52 </li> 53 <li>Checkout Clang: 54 <ul> 55 <li><tt>cd llvm/tools</tt></li> 56 <li><tt>svn co http://llvm.org/svn/llvm-project/cfe/trunk clang</tt></li> 57 <li><tt>cd ../..</tt></li> 58 </ul> 59 </li> 60 <li>Checkout extra Clang Tools: (optional) 61 <ul> 62 <li><tt>cd llvm/tools/clang/tools</tt></li> 63 <li><tt>svn co http://llvm.org/svn/llvm-project/clang-tools-extra/trunk 64 extra</tt></li> 65 <li><tt>cd ../../../..</tt></li> 66 </ul> 67 </li> 68 <li>Checkout Compiler-RT: 69 <ul> 70 <li><tt>cd llvm/projects</tt></li> 71 <li><tt>svn co http://llvm.org/svn/llvm-project/compiler-rt/trunk 72 compiler-rt</tt></li> 73 <li><tt>cd ../..</tt></li> 74 </ul> 75 </li> 76 <li>Build LLVM and Clang: 77 <ul> 78 <li><tt>mkdir build</tt> (for building without polluting the source dir) 79 </li> 80 <li><tt>cd build</tt></li> 81 <li><tt>../llvm/configure</tt></li> 82 <li><tt>make</tt></li> 83 <li>This builds both LLVM and Clang for debug mode.</li> 84 <li>Note: For subsequent Clang development, you can just do make at the 85 clang directory level.</li> 86 <li>It is also possible to use CMake instead of the makefiles. With CMake 87 it is possible to generate project files for several IDEs: Xcode, Eclipse 88 CDT4, CodeBlocks, Qt-Creator (use the CodeBlocks generator), KDevelop3.</li> 89 </ul> 90 </li> 91 92 <li>If you intend to use Clang's C++ support, you may need to tell it how 93 to find your C++ standard library headers. In general, Clang will detect 94 the best version of libstdc++ headers available and use them - it will 95 look both for system installations of libstdc++ as well as installations 96 adjacent to Clang itself. If your configuration fits neither of these 97 scenarios, you can use the <tt>--with-gcc-toolchain</tt> configure option 98 to tell Clang where the gcc containing the desired libstdc++ is installed. 99 </li> 100 <li>Try it out (assuming you add llvm/Debug+Asserts/bin to your path): 101 <ul> 102 <li><tt>clang --help</tt></li> 103 <li><tt>clang file.c -fsyntax-only</tt> (check for correctness)</li> 104 <li><tt>clang file.c -S -emit-llvm -o -</tt> (print out unoptimized llvm code)</li> 105 <li><tt>clang file.c -S -emit-llvm -o - -O3</tt></li> 106 <li><tt>clang file.c -S -O3 -o -</tt> (output native machine code)</li> 107 </ul> 108 </li> 109 </ol> 110 111 <p>Note that the C front-end uses LLVM, but does not depend on llvm-gcc. If you 112 encounter problems with building Clang, make sure you have the latest SVN 113 version of LLVM. LLVM contains support libraries for Clang that will be updated 114 as well as development on Clang progresses.</p> 115 116 <h3>Simultaneously Building Clang and LLVM:</h3> 117 118 <p>Once you have checked out Clang into the llvm source tree it will build along 119 with the rest of <tt>llvm</tt>. To build all of LLVM and Clang together all at 120 once simply run <tt>make</tt> from the root LLVM directory.</p> 121 122 <p><em>Note:</em> Observe that Clang is technically part of a separate 123 Subversion repository. As mentioned above, the latest Clang sources are tied to 124 the latest sources in the LLVM tree. You can update your toplevel LLVM project 125 and all (possibly unrelated) projects inside it with <tt><b>make 126 update</b></tt>. This will run <tt>svn update</tt> on all subdirectories related 127 to subversion. </p> 128 129 <h3 id="buildWindows">Using Visual Studio</h3> 130 131 <p>The following details setting up for and building Clang on Windows using 132 Visual Studio:</p> 133 134 <ol> 135 <li>Get the required tools: 136 <ul> 137 <li><b>Subversion</b>. Source code control program. Get it from: 138 <a href="http://subversion.tigris.org/getting.html"> 139 http://subversion.tigris.org/getting.html</a></li> 140 <li><b>CMake</b>. This is used for generating Visual Studio solution and 141 project files. Get it from: 142 <a href="http://www.cmake.org/cmake/resources/software.html"> 143 http://www.cmake.org/cmake/resources/software.html</a></li> 144 <li><b>Visual Studio 2012 or later</b></li> 145 <li><b>Python</b>. This is needed only if you will be running the tests 146 (which is essential, if you will be developing for clang). 147 Get it from: 148 <a href="http://www.python.org/download/"> 149 http://www.python.org/download/</a></li> 150 <li><b>GnuWin32 tools</b> 151 These are also necessary for running the tests. 152 (Note that the grep from MSYS or Cygwin doesn't work with the tests 153 because of embedded double-quotes in the search strings. The GNU 154 grep does work in this case.) 155 Get them from <a href="http://getgnuwin32.sourceforge.net/"> 156 http://getgnuwin32.sourceforge.net/</a>.</li> 157 </ul> 158 </li> 159 160 <li>Checkout LLVM: 161 <ul> 162 <li><tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li> 163 </ul> 164 </li> 165 <li>Checkout Clang: 166 <ul> 167 <li><tt>cd llvm\tools</tt> 168 <li><tt>svn co http://llvm.org/svn/llvm-project/cfe/trunk clang</tt></li> 169 </ul> 170 </li> 171 <li>Run CMake to generate the Visual Studio solution and project files: 172 <ul> 173 <li><tt>cd ..\..</tt> (back to where you started)</li> 174 <li><tt>mkdir build</tt> (for building without polluting the source dir)</li> 175 <li><tt>cd build</tt></li> 176 <li>If you are using Visual Studio 2012: <tt>cmake -G "Visual Studio 11" ..\llvm</tt></li> 177 <li>See the <a href="http://www.llvm.org/docs/CMake.html">LLVM CMake guide</a> for 178 more information on other configuration options for CMake.</li> 179 <li>The above, if successful, will have created an LLVM.sln file in the 180 <tt>build</tt> directory. 181 </ul> 182 </li> 183 <li>Build Clang: 184 <ul> 185 <li>Open LLVM.sln in Visual Studio.</li> 186 <li>Build the "clang" project for just the compiler driver and front end, or 187 the "ALL_BUILD" project to build everything, including tools.</li> 188 </ul> 189 </li> 190 <li>Try it out (assuming you added llvm/debug/bin to your path). (See the 191 running examples from above.)</li> 192 <li>See <a href="hacking.html#testingWindows"> 193 Hacking on clang - Testing using Visual Studio on Windows</a> for information 194 on running regression tests on Windows.</li> 195 </ol> 196 197 <p>Note that once you have checked out both llvm and clang, to synchronize 198 to the latest code base, use the <tt>svn update</tt> command in both the 199 llvm and llvm\tools\clang directories, as they are separate repositories.</p> 200 201 <h2 id="driver">Clang Compiler Driver (Drop-in Substitute for GCC)</h2> 202 203 <p>The <tt>clang</tt> tool is the compiler driver and front-end, which is 204 designed to be a drop-in replacement for the <tt>gcc</tt> command. Here are 205 some examples of how to use the high-level driver: 206 </p> 207 208 <pre class="code"> 209 $ <b>cat t.c</b> 210 #include <stdio.h> 211 int main(int argc, char **argv) { printf("hello world\n"); } 212 $ <b>clang t.c</b> 213 $ <b>./a.out</b> 214 hello world 215 </pre> 216 217 <p>The 'clang' driver is designed to work as closely to GCC as possible to 218 maximize portability. The only major difference between the two is that 219 Clang defaults to gnu99 mode while GCC defaults to gnu89 mode. If you see 220 weird link-time errors relating to inline functions, try passing -std=gnu89 221 to clang.</p> 222 223 <h2>Examples of using Clang</h2> 224 225 <!-- Thanks to 226 http://shiflett.org/blog/2006/oct/formatting-and-highlighting-php-code-listings 227 Site suggested using pre in CSS, but doesn't work in IE, so went for the <pre> 228 tag. --> 229 230 <pre class="code"> 231 $ <b>cat ~/t.c</b> 232 typedef float V __attribute__((vector_size(16))); 233 V foo(V a, V b) { return a+b*a; } 234 </pre> 235 236 237 <h3>Preprocessing:</h3> 238 239 <pre class="code"> 240 $ <b>clang ~/t.c -E</b> 241 # 1 "/Users/sabre/t.c" 1 242 243 typedef float V __attribute__((vector_size(16))); 244 245 V foo(V a, V b) { return a+b*a; } 246 </pre> 247 248 249 <h3>Type checking:</h3> 250 251 <pre class="code"> 252 $ <b>clang -fsyntax-only ~/t.c</b> 253 </pre> 254 255 256 <h3>GCC options:</h3> 257 258 <pre class="code"> 259 $ <b>clang -fsyntax-only ~/t.c -pedantic</b> 260 /Users/sabre/t.c:2:17: <span style="color:magenta">warning:</span> extension used 261 <span style="color:darkgreen">typedef float V __attribute__((vector_size(16)));</span> 262 <span style="color:blue"> ^</span> 263 1 diagnostic generated. 264 </pre> 265 266 267 <h3>Pretty printing from the AST:</h3> 268 269 <p>Note, the <tt>-cc1</tt> argument indicates the compiler front-end, and 270 not the driver, should be run. The compiler front-end has several additional 271 Clang specific features which are not exposed through the GCC compatible driver 272 interface.</p> 273 274 <pre class="code"> 275 $ <b>clang -cc1 ~/t.c -ast-print</b> 276 typedef float V __attribute__(( vector_size(16) )); 277 V foo(V a, V b) { 278 return a + b * a; 279 } 280 </pre> 281 282 283 <h3>Code generation with LLVM:</h3> 284 285 <pre class="code"> 286 $ <b>clang ~/t.c -S -emit-llvm -o -</b> 287 define <4 x float> @foo(<4 x float> %a, <4 x float> %b) { 288 entry: 289 %mul = mul <4 x float> %b, %a 290 %add = add <4 x float> %mul, %a 291 ret <4 x float> %add 292 } 293 $ <b>clang -fomit-frame-pointer -O3 -S -o - t.c</b> <i># On x86_64</i> 294 ... 295 _foo: 296 Leh_func_begin1: 297 mulps %xmm0, %xmm1 298 addps %xmm1, %xmm0 299 ret 300 Leh_func_end1: 301 </pre> 302 303 </div> 304 </body> 305 </html> 306
