1 ================================================================== 2 Getting Started with the LLVM System using Microsoft Visual Studio 3 ================================================================== 4 5 .. contents:: 6 :local: 7 8 9 Overview 10 ======== 11 Welcome to LLVM on Windows! This document only covers LLVM on Windows using 12 Visual Studio, not mingw or cygwin. In order to get started, you first need to 13 know some basic information. 14 15 There are many different projects that compose LLVM. The first is the LLVM 16 suite. This contains all of the tools, libraries, and header files needed to 17 use LLVM. It contains an assembler, disassembler, 18 bitcode analyzer and bitcode optimizer. It also contains a test suite that can 19 be used to test the LLVM tools. 20 21 Another useful project on Windows is `Clang <http://clang.llvm.org/>`_. 22 Clang is a C family ([Objective]C/C++) compiler. Clang mostly works on 23 Windows, but does not currently understand all of the Microsoft extensions 24 to C and C++. Because of this, clang cannot parse the C++ standard library 25 included with Visual Studio, nor parts of the Windows Platform SDK. However, 26 most standard C programs do compile. Clang can be used to emit bitcode, 27 directly emit object files or even linked executables using Visual Studio's 28 ``link.exe``. 29 30 The large LLVM test suite cannot be run on the Visual Studio port at this 31 time. 32 33 Most of the tools build and work. ``bugpoint`` does build, but does 34 not work. 35 36 Additional information about the LLVM directory structure and tool chain 37 can be found on the main `Getting Started <GettingStarted.html>`_ page. 38 39 40 Requirements 41 ============ 42 Before you begin to use the LLVM system, review the requirements given 43 below. This may save you some trouble by knowing ahead of time what hardware 44 and software you will need. 45 46 Hardware 47 -------- 48 Any system that can adequately run Visual Studio 2010 is fine. The LLVM 49 source tree and object files, libraries and executables will consume 50 approximately 3GB. 51 52 Software 53 -------- 54 You will need Visual Studio 2010 or higher. Earlier versions of Visual 55 Studio have bugs, are not completely compatible, or do not support the C++ 56 standard well enough. 57 58 You will also need the `CMake <http://www.cmake.org/>`_ build system since it 59 generates the project files you will use to build with. 60 61 If you would like to run the LLVM tests you will need `Python 62 <http://www.python.org/>`_. Versions 2.4-2.7 are known to work. You will need 63 `GnuWin32 <http://gnuwin32.sourceforge.net/>`_ tools, too. 64 65 Do not install the LLVM directory tree into a path containing spaces (e.g. 66 ``C:\Documents and Settings\...``) as the configure step will fail. 67 68 69 Getting Started 70 =============== 71 Here's the short story for getting up and running quickly with LLVM: 72 73 1. Read the documentation. 74 2. Seriously, read the documentation. 75 3. Remember that you were warned twice about reading the documentation. 76 4. Get the Source Code 77 78 * With the distributed files: 79 80 1. ``cd <where-you-want-llvm-to-live>`` 81 2. ``gunzip --stdout llvm-VERSION.tar.gz | tar -xvf -`` 82 (*or use WinZip*) 83 3. ``cd llvm`` 84 85 * With anonymous Subversion access: 86 87 1. ``cd <where-you-want-llvm-to-live>`` 88 2. ``svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm`` 89 3. ``cd llvm`` 90 91 5. Use `CMake <http://www.cmake.org/>`_ to generate up-to-date project files: 92 93 * Once CMake is installed then the simplest way is to just start the 94 CMake GUI, select the directory where you have LLVM extracted to, and 95 the default options should all be fine. One option you may really 96 want to change, regardless of anything else, might be the 97 ``CMAKE_INSTALL_PREFIX`` setting to select a directory to INSTALL to 98 once compiling is complete, although installation is not mandatory for 99 using LLVM. Another important option is ``LLVM_TARGETS_TO_BUILD``, 100 which controls the LLVM target architectures that are included on the 101 build. 102 * See the `LLVM CMake guide <CMake.html>`_ for detailed information about 103 how to configure the LLVM build. 104 105 6. Start Visual Studio 106 107 * In the directory you created the project files will have an ``llvm.sln`` 108 file, just double-click on that to open Visual Studio. 109 110 7. Build the LLVM Suite: 111 112 * The projects may still be built individually, but to build them all do 113 not just select all of them in batch build (as some are meant as 114 configuration projects), but rather select and build just the 115 ``ALL_BUILD`` project to build everything, or the ``INSTALL`` project, 116 which first builds the ``ALL_BUILD`` project, then installs the LLVM 117 headers, libs, and other useful things to the directory set by the 118 ``CMAKE_INSTALL_PREFIX`` setting when you first configured CMake. 119 * The Fibonacci project is a sample program that uses the JIT. Modify the 120 project's debugging properties to provide a numeric command line argument 121 or run it from the command line. The program will print the 122 corresponding fibonacci value. 123 124 8. Test LLVM on Visual Studio: 125 126 * If ``%PATH%`` does not contain GnuWin32, you may specify 127 ``LLVM_LIT_TOOLS_DIR`` on CMake for the path to GnuWin32. 128 * You can run LLVM tests by merely building the project "check". The test 129 results will be shown in the VS output window. 130 131 .. FIXME: Is it up-to-date? 132 133 9. Test LLVM: 134 135 * The LLVM tests can be run by changing directory to the llvm source 136 directory and running: 137 138 .. code-block:: bat 139 140 C:\..\llvm> python ..\build\bin\llvm-lit --param build_config=Win32 --param build_mode=Debug --param llvm_site_config=../build/test/lit.site.cfg test 141 142 This example assumes that Python is in your PATH variable, you 143 have built a Win32 Debug version of llvm with a standard out of 144 line build. You should not see any unexpected failures, but will 145 see many unsupported tests and expected failures. 146 147 A specific test or test directory can be run with: 148 149 .. code-block:: bat 150 151 C:\..\llvm> python ..\build\bin\llvm-lit --param build_config=Win32 --param build_mode=Debug --param llvm_site_config=../build/test/lit.site.cfg test/path/to/test 152 153 154 An Example Using the LLVM Tool Chain 155 ==================================== 156 157 1. First, create a simple C file, name it '``hello.c``': 158 159 .. code-block:: c 160 161 #include <stdio.h> 162 int main() { 163 printf("hello world\n"); 164 return 0; 165 } 166 167 2. Next, compile the C file into a LLVM bitcode file: 168 169 .. code-block:: bat 170 171 C:\..> clang -c hello.c -emit-llvm -o hello.bc 172 173 This will create the result file ``hello.bc`` which is the LLVM bitcode 174 that corresponds the compiled program and the library facilities that 175 it required. You can execute this file directly using ``lli`` tool, 176 compile it to native assembly with the ``llc``, optimize or analyze it 177 further with the ``opt`` tool, etc. 178 179 Alternatively you can directly output an executable with clang with: 180 181 .. code-block:: bat 182 183 C:\..> clang hello.c -o hello.exe 184 185 The ``-o hello.exe`` is required because clang currently outputs ``a.out`` 186 when neither ``-o`` nor ``-c`` are given. 187 188 3. Run the program using the just-in-time compiler: 189 190 .. code-block:: bat 191 192 C:\..> lli hello.bc 193 194 4. Use the ``llvm-dis`` utility to take a look at the LLVM assembly code: 195 196 .. code-block:: bat 197 198 C:\..> llvm-dis < hello.bc | more 199 200 5. Compile the program to object code using the LLC code generator: 201 202 .. code-block:: bat 203 204 C:\..> llc -filetype=obj hello.bc 205 206 6. Link to binary using Microsoft link: 207 208 .. code-block:: bat 209 210 C:\..> link hello.obj -defaultlib:libcmt 211 212 7. Execute the native code program: 213 214 .. code-block:: bat 215 216 C:\..> hello.exe 217 218 219 Common Problems 220 =============== 221 If you are having problems building or using LLVM, or if you have any other 222 general questions about LLVM, please consult the `Frequently Asked Questions 223 <FAQ.html>`_ page. 224 225 226 Links 227 ===== 228 This document is just an **introduction** to how to use LLVM to do some simple 229 things... there are many more interesting and complicated things that you can 230 do that aren't documented here (but we'll gladly accept a patch if you want to 231 write something up!). For more information about LLVM, check out: 232 233 * `LLVM homepage <http://llvm.org/>`_ 234 * `LLVM doxygen tree <http://llvm.org/doxygen/>`_ 235 236
