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 has been released as part of regular LLVM releases since LLVM 2.6. You 27 can download the release versions 28 from <a href="http://llvm.org/releases/">http://llvm.org/releases/</a>.</p> 29 30 <h2 id="build">Building Clang and Working with the Code</h2> 31 32 <h3 id="buildNix">On Unix-like Systems</h3> 33 34 <p>If you would like to check out and build Clang, the current procedure is as 35 follows:</p> 36 37 <ol> 38 <li>Get the required tools. 39 <ul> 40 <li>See 41 <a href="http://llvm.org/docs/GettingStarted.html#requirements"> 42 Getting Started with the LLVM System - Requirements</a>.</li> 43 <li>Note also that Python is needed for running the test suite. 44 Get it at: <a href="http://www.python.org/download"> 45 http://www.python.org/download</a></li> 46 </ul> 47 48 <li>Checkout LLVM: 49 <ul> 50 <li>Change directory to where you want the llvm directory placed.</li> 51 <li><tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li> 52 </ul> 53 </li> 54 <li>Checkout Clang: 55 <ul> 56 <li><tt>cd llvm/tools</tt> 57 <li><tt>svn co http://llvm.org/svn/llvm-project/cfe/trunk clang</tt></li> 58 </ul> 59 </li> 60 <li>Checkout Compiler-RT: 61 <ul> 62 <li><tt>cd ../..</tt> (back to where you started)</li> 63 <li><tt>cd llvm/projects</tt> 64 <li><tt>svn co http://llvm.org/svn/llvm-project/compiler-rt/trunk 65 compiler-rt</tt></li> 66 </ul> 67 </li> 68 <li>Build LLVM and Clang: 69 <ul> 70 <li><tt>cd ../..</tt> (back to where you started)</li> 71 <li><tt>mkdir build</tt> (for building without polluting the source dir) 72 </li> 73 <li><tt>cd build</tt></li> 74 <li><tt>../llvm/configure</tt></li> 75 <li><tt>make</tt></li> 76 <li>This builds both LLVM and Clang for debug mode.</li> 77 <li>Note: For subsequent Clang development, you can just do make at the 78 clang directory level.</li> 79 <li>It is also possible to use CMake instead of the makefiles. With CMake 80 it is also possible to generate project files for several IDEs: Eclipse 81 CDT4, CodeBlocks, Qt-Creator (use the CodeBlocks generator), KDevelop3.</li> 82 </ul> 83 </li> 84 85 <li>If you intend to work on Clang C++ support, you may need to tell it how 86 to find your C++ standard library headers. If Clang cannot find your 87 system libstdc++ headers, please follow these instructions: 88 <ul> 89 <li>'<tt>gcc -v -x c++ /dev/null -fsyntax-only</tt>' to get the 90 path.</li> 91 <li>Look for the comment "FIXME: temporary hack: 92 hard-coded paths" in <tt>clang/lib/Frontend/InitHeaderSearch.cpp</tt> and 93 change the lines below to include that path.</li> 94 </ul> 95 </li> 96 <li>Try it out (assuming you add llvm/Debug+Asserts/bin to your path): 97 <ul> 98 <li><tt>clang --help</tt></li> 99 <li><tt>clang file.c -fsyntax-only</tt> (check for correctness)</li> 100 <li><tt>clang file.c -S -emit-llvm -o -</tt> (print out unoptimized llvm code)</li> 101 <li><tt>clang file.c -S -emit-llvm -o - -O3</tt></li> 102 <li><tt>clang file.c -S -O3 -o -</tt> (output native machine code)</li> 103 </ul> 104 </li> 105 </ol> 106 107 <p>Note that the C front-end uses LLVM, but does not depend on llvm-gcc. If you 108 encounter problems with building Clang, make sure you have the latest SVN 109 version of LLVM. LLVM contains support libraries for Clang that will be updated 110 as well as development on Clang progresses.</p> 111 112 <h3>Simultaneously Building Clang and LLVM:</h3> 113 114 <p>Once you have checked out Clang into the llvm source tree it will build along 115 with the rest of <tt>llvm</tt>. To build all of LLVM and Clang together all at 116 once simply run <tt>make</tt> from the root LLVM directory.</p> 117 118 <p><em>Note:</em> Observe that Clang is technically part of a separate 119 Subversion repository. As mentioned above, the latest Clang sources are tied to 120 the latest sources in the LLVM tree. You can update your toplevel LLVM project 121 and all (possibly unrelated) projects inside it with <tt><b>make 122 update</b></tt>. This will run <tt>svn update</tt> on all subdirectories related 123 to subversion. </p> 124 125 <h3 id="buildWindows">Using Visual Studio</h3> 126 127 <p>The following details setting up for and building Clang on Windows using 128 Visual Studio:</p> 129 130 <ol> 131 <li>Get the required tools: 132 <ul> 133 <li><b>Subversion</b>. Source code control program. Get it from: 134 <a href="http://subversion.tigris.org/getting.html"> 135 http://subversion.tigris.org/getting.html</a></li> 136 <li><b>cmake</b>. This is used for generating Visual Studio solution and 137 project files. Get it from: 138 <a href="http://www.cmake.org/cmake/resources/software.html"> 139 http://www.cmake.org/cmake/resources/software.html</a></li> 140 <li><b>Visual Studio 2008 or 2010</b></li> 141 <li><b>Python</b>. This is needed only if you will be running the tests 142 (which is essential, if you will be developing for clang). 143 Get it from: 144 <a href="http://www.python.org/download/"> 145 http://www.python.org/download/</a></li> 146 <li><b>GnuWin32 tools</b> 147 These are also necessary for running the tests. 148 (Note that the grep from MSYS or Cygwin doesn't work with the tests 149 because of embedded double-quotes in the search strings. The GNU 150 grep does work in this case.) 151 Get them from <a href="http://getgnuwin32.sourceforge.net/"> 152 http://getgnuwin32.sourceforge.net/</a>.</li> 153 </ul> 154 </li> 155 156 <li>Checkout LLVM: 157 <ul> 158 <li><tt>svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm</tt></li> 159 </ul> 160 </li> 161 <li>Checkout Clang: 162 <ul> 163 <li><tt>cd llvm\tools</tt> 164 <li><tt>svn co http://llvm.org/svn/llvm-project/cfe/trunk clang</tt></li> 165 </ul> 166 </li> 167 <li>Run cmake to generate the Visual Studio solution and project files: 168 <ul> 169 <li><tt>cd ..\..</tt> (back to where you started)</li> 170 <li><tt>mkdir build</tt> (for building without polluting the source dir)</li> 171 <li><tt>cd build</tt></li> 172 <li>If you are using Visual Studio 2008: <tt>cmake -G "Visual Studio 9 2008" ..\llvm</tt></li> 173 <li>Or if you are using Visual Studio 2010: <tt>cmake -G "Visual Studio 10" ..\llvm</tt></li> 174 <li>By default, cmake will target LLVM to X86. If you want all targets 175 (needed if you want to run the LLVM tests), add the <tt>-DLLVM_TARGETS_TO_BUILD=all</tt> option to the 176 cmake command line. Or specify a target from the LLVM_TARGETS_TO_BUILD 177 definition in CMakeLists.txt.</li> 178 <li>See the <a href="http://www.llvm.org/docs/CMake.html">LLVM CMake guide</a> for 179 more information on other configuration options for cmake.</li> 180 <li>The above, if successful, will have created an LLVM.sln file in the 181 <tt>build</tt> directory. 182 </ul> 183 </li> 184 <li>Build Clang: 185 <ul> 186 <li>Open LLVM.sln in Visual Studio.</li> 187 <li>Build the "clang" project for just the compiler driver and front end, or 188 the "ALL_BUILD" project to build everything, including tools.</li> 189 </ul> 190 </li> 191 <li>Try it out (assuming you added llvm/debug/bin to your path). (See the 192 running examples from above.)</li> 193 <li>See <a href="hacking.html#testingWindows"> 194 Hacking on clang - Testing using Visual Studio on Windows</a> for information 195 on running regression tests on Windows.</li> 196 </ol> 197 198 <p>Note that once you have checked out both llvm and clang, to synchronize 199 to the latest code base, use the <tt>svn update</tt> command in both the 200 llvm and llvm\tools\clang directories, as they are separate repositories.</p> 201 202 <h2 id="driver">Clang Compiler Driver (Drop-in Substitute for GCC)</h2> 203 204 <p>The <tt>clang</tt> tool is the compiler driver and front-end, which is 205 designed to be a drop-in replacement for the <tt>gcc</tt> command. Here are 206 some examples of how to use the high-level driver: 207 </p> 208 209 <pre class="code"> 210 $ <b>cat t.c</b> 211 #include <stdio.h> 212 int main(int argc, char **argv) { printf("hello world\n"); } 213 $ <b>clang t.c</b> 214 $ <b>./a.out</b> 215 hello world 216 </pre> 217 218 <p>The 'clang' driver is designed to work as closely to GCC as possible to 219 maximize portability. The only major difference between the two is that 220 Clang defaults to gnu99 mode while GCC defaults to gnu89 mode. If you see 221 weird link-time errors relating to inline functions, try passing -std=gnu89 222 to clang.</p> 223 224 <h2>Examples of using Clang</h2> 225 226 <!-- Thanks to 227 http://shiflett.org/blog/2006/oct/formatting-and-highlighting-php-code-listings 228 Site suggested using pre in CSS, but doesn't work in IE, so went for the <pre> 229 tag. --> 230 231 <pre class="code"> 232 $ <b>cat ~/t.c</b> 233 typedef float V __attribute__((vector_size(16))); 234 V foo(V a, V b) { return a+b*a; } 235 </pre> 236 237 238 <h3>Preprocessing:</h3> 239 240 <pre class="code"> 241 $ <b>clang ~/t.c -E</b> 242 # 1 "/Users/sabre/t.c" 1 243 244 typedef float V __attribute__((vector_size(16))); 245 246 V foo(V a, V b) { return a+b*a; } 247 </pre> 248 249 250 <h3>Type checking:</h3> 251 252 <pre class="code"> 253 $ <b>clang -fsyntax-only ~/t.c</b> 254 </pre> 255 256 257 <h3>GCC options:</h3> 258 259 <pre class="code"> 260 $ <b>clang -fsyntax-only ~/t.c -pedantic</b> 261 /Users/sabre/t.c:2:17: <span style="color:magenta">warning:</span> extension used 262 <span style="color:darkgreen">typedef float V __attribute__((vector_size(16)));</span> 263 <span style="color:blue"> ^</span> 264 1 diagnostic generated. 265 </pre> 266 267 268 <h3>Pretty printing from the AST:</h3> 269 270 <p>Note, the <tt>-cc1</tt> argument indicates the the compiler front-end, and 271 not the driver, should be run. The compiler front-end has several additional 272 Clang specific features which are not exposed through the GCC compatible driver 273 interface.</p> 274 275 <pre class="code"> 276 $ <b>clang -cc1 ~/t.c -ast-print</b> 277 typedef float V __attribute__(( vector_size(16) )); 278 V foo(V a, V b) { 279 return a + b * a; 280 } 281 </pre> 282 283 284 <h3>Code generation with LLVM:</h3> 285 286 <pre class="code"> 287 $ <b>clang ~/t.c -S -emit-llvm -o -</b> 288 define <4 x float> @foo(<4 x float> %a, <4 x float> %b) { 289 entry: 290 %mul = mul <4 x float> %b, %a 291 %add = add <4 x float> %mul, %a 292 ret <4 x float> %add 293 } 294 $ <b>clang -fomit-frame-pointer -O3 -S -o - t.c</b> <i># On x86_64</i> 295 ... 296 _foo: 297 Leh_func_begin1: 298 mulps %xmm0, %xmm1 299 addps %xmm1, %xmm0 300 ret 301 Leh_func_end1: 302 </pre> 303 304 </div> 305 </body> 306 </html> 307
