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 piece is the 16 LLVM suite. This contains all of the tools, libraries, and header files needed 17 to use LLVM. It contains an assembler, disassembler, bitcode analyzer and 18 bitcode optimizer. It also contains basic regression tests that can be used to 19 test the LLVM tools and the Clang front end. 20 21 The second piece is the `Clang <http://clang.llvm.org/>`_ front end. This 22 component compiles C, C++, Objective C, and Objective C++ code into LLVM 23 bitcode. Clang typically uses LLVM libraries to optimize the bitcode and emit 24 machine code. LLVM fully supports the COFF object file format, which is 25 compatible with all other existing Windows toolchains. 26 27 The last major part of LLVM, the execution Test Suite, does not run on Windows, 28 and this document does not discuss it. 29 30 Additional information about the LLVM directory structure and tool chain 31 can be found on the main :doc:`GettingStarted` page. 32 33 34 Requirements 35 ============ 36 Before you begin to use the LLVM system, review the requirements given 37 below. This may save you some trouble by knowing ahead of time what hardware 38 and software you will need. 39 40 Hardware 41 -------- 42 Any system that can adequately run Visual Studio 2013 is fine. The LLVM 43 source tree and object files, libraries and executables will consume 44 approximately 3GB. 45 46 Software 47 -------- 48 You will need Visual Studio 2013 or higher, with the latest Update installed. 49 50 You will also need the `CMake <http://www.cmake.org/>`_ build system since it 51 generates the project files you will use to build with. CMake 2.8.12.2 is the 52 minimum required version for building with Visual Studio, though the latest 53 version of CMake is recommended. 54 55 If you would like to run the LLVM tests you will need `Python 56 <http://www.python.org/>`_. Version 2.7 and newer are known to work. You will 57 need `GnuWin32 <http://gnuwin32.sourceforge.net/>`_ tools, too. 58 59 Do not install the LLVM directory tree into a path containing spaces (e.g. 60 ``C:\Documents and Settings\...``) as the configure step will fail. 61 62 63 Getting Started 64 =============== 65 Here's the short story for getting up and running quickly with LLVM: 66 67 1. Read the documentation. 68 2. Seriously, read the documentation. 69 3. Remember that you were warned twice about reading the documentation. 70 4. Get the Source Code 71 72 * With the distributed files: 73 74 1. ``cd <where-you-want-llvm-to-live>`` 75 2. ``gunzip --stdout llvm-VERSION.tar.gz | tar -xvf -`` 76 (*or use WinZip*) 77 3. ``cd llvm`` 78 79 * With anonymous Subversion access: 80 81 1. ``cd <where-you-want-llvm-to-live>`` 82 2. ``svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm`` 83 3. ``cd llvm`` 84 85 5. Use `CMake <http://www.cmake.org/>`_ to generate up-to-date project files: 86 87 * Once CMake is installed then the simplest way is to just start the 88 CMake GUI, select the directory where you have LLVM extracted to, and 89 the default options should all be fine. One option you may really 90 want to change, regardless of anything else, might be the 91 ``CMAKE_INSTALL_PREFIX`` setting to select a directory to INSTALL to 92 once compiling is complete, although installation is not mandatory for 93 using LLVM. Another important option is ``LLVM_TARGETS_TO_BUILD``, 94 which controls the LLVM target architectures that are included on the 95 build. 96 * If CMake complains that it cannot find the compiler, make sure that 97 you have the Visual Studio C++ Tools installed, not just Visual Studio 98 itself (trying to create a C++ project in Visual Studio will generally 99 download the C++ tools if they haven't already been). 100 * See the :doc:`LLVM CMake guide <CMake>` for detailed information about 101 how to configure the LLVM build. 102 * CMake generates project files for all build types. To select a specific 103 build type, use the Configuration manager from the VS IDE or the 104 ``/property:Configuration`` command line option when using MSBuild. 105 106 6. Start Visual Studio 107 108 * In the directory you created the project files will have an ``llvm.sln`` 109 file, just double-click on that to open Visual Studio. 110 111 7. Build the LLVM Suite: 112 113 * The projects may still be built individually, but to build them all do 114 not just select all of them in batch build (as some are meant as 115 configuration projects), but rather select and build just the 116 ``ALL_BUILD`` project to build everything, or the ``INSTALL`` project, 117 which first builds the ``ALL_BUILD`` project, then installs the LLVM 118 headers, libs, and other useful things to the directory set by the 119 ``CMAKE_INSTALL_PREFIX`` setting when you first configured CMake. 120 * The Fibonacci project is a sample program that uses the JIT. Modify the 121 project's debugging properties to provide a numeric command line argument 122 or run it from the command line. The program will print the 123 corresponding fibonacci value. 124 125 8. Test LLVM in Visual Studio: 126 127 * If ``%PATH%`` does not contain GnuWin32, you may specify 128 ``LLVM_LIT_TOOLS_DIR`` on CMake for the path to GnuWin32. 129 * You can run LLVM tests by merely building the project "check". The test 130 results will be shown in the VS output window. 131 132 9. Test LLVM on the command line: 133 134 * The LLVM tests can be run by changing directory to the llvm source 135 directory and running: 136 137 .. code-block:: bat 138 139 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 140 141 This example assumes that Python is in your PATH variable, you 142 have built a Win32 Debug version of llvm with a standard out of 143 line build. You should not see any unexpected failures, but will 144 see many unsupported tests and expected failures. 145 146 A specific test or test directory can be run with: 147 148 .. code-block:: bat 149 150 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 151 152 153 An Example Using the LLVM Tool Chain 154 ==================================== 155 156 1. First, create a simple C file, name it '``hello.c``': 157 158 .. code-block:: c 159 160 #include <stdio.h> 161 int main() { 162 printf("hello world\n"); 163 return 0; 164 } 165 166 2. Next, compile the C file into an LLVM bitcode file: 167 168 .. code-block:: bat 169 170 C:\..> clang -c hello.c -emit-llvm -o hello.bc 171 172 This will create the result file ``hello.bc`` which is the LLVM bitcode 173 that corresponds the compiled program and the library facilities that 174 it required. You can execute this file directly using ``lli`` tool, 175 compile it to native assembly with the ``llc``, optimize or analyze it 176 further with the ``opt`` tool, etc. 177 178 Alternatively you can directly output an executable with clang with: 179 180 .. code-block:: bat 181 182 C:\..> clang hello.c -o hello.exe 183 184 The ``-o hello.exe`` is required because clang currently outputs ``a.out`` 185 when neither ``-o`` nor ``-c`` are given. 186 187 3. Run the program using the just-in-time compiler: 188 189 .. code-block:: bat 190 191 C:\..> lli hello.bc 192 193 4. Use the ``llvm-dis`` utility to take a look at the LLVM assembly code: 194 195 .. code-block:: bat 196 197 C:\..> llvm-dis < hello.bc | more 198 199 5. Compile the program to object code using the LLC code generator: 200 201 .. code-block:: bat 202 203 C:\..> llc -filetype=obj hello.bc 204 205 6. Link to binary using Microsoft link: 206 207 .. code-block:: bat 208 209 C:\..> link hello.obj -defaultlib:libcmt 210 211 7. Execute the native code program: 212 213 .. code-block:: bat 214 215 C:\..> hello.exe 216 217 218 Common Problems 219 =============== 220 If you are having problems building or using LLVM, or if you have any other 221 general questions about LLVM, please consult the :doc:`Frequently Asked Questions 222 <FAQ>` page. 223 224 225 Links 226 ===== 227 This document is just an **introduction** to how to use LLVM to do some simple 228 things... there are many more interesting and complicated things that you can 229 do that aren't documented here (but we'll gladly accept a patch if you want to 230 write something up!). For more information about LLVM, check out: 231 232 * `LLVM homepage <http://llvm.org/>`_ 233 * `LLVM doxygen tree <http://llvm.org/doxygen/>`_ 234 235
