1================================================================== 2Getting Started with the LLVM System using Microsoft Visual Studio 3================================================================== 4 5.. contents:: 6 :local: 7 8 9Overview 10======== 11Welcome to LLVM on Windows! This document only covers LLVM on Windows using 12Visual Studio, not mingw or cygwin. In order to get started, you first need to 13know some basic information. 14 15There are many different projects that compose LLVM. The first piece is the 16LLVM suite. This contains all of the tools, libraries, and header files needed 17to use LLVM. It contains an assembler, disassembler, bitcode analyzer and 18bitcode optimizer. It also contains basic regression tests that can be used to 19test the LLVM tools and the Clang front end. 20 21The second piece is the `Clang <http://clang.llvm.org/>`_ front end. This 22component compiles C, C++, Objective C, and Objective C++ code into LLVM 23bitcode. Clang typically uses LLVM libraries to optimize the bitcode and emit 24machine code. LLVM fully supports the COFF object file format, which is 25compatible with all other existing Windows toolchains. 26 27The last major part of LLVM, the execution Test Suite, does not run on Windows, 28and this document does not discuss it. 29 30Additional information about the LLVM directory structure and tool chain 31can be found on the main :doc:`GettingStarted` page. 32 33 34Requirements 35============ 36Before you begin to use the LLVM system, review the requirements given 37below. This may save you some trouble by knowing ahead of time what hardware 38and software you will need. 39 40Hardware 41-------- 42Any system that can adequately run Visual Studio 2015 is fine. The LLVM 43source tree and object files, libraries and executables will consume 44approximately 3GB. 45 46Software 47-------- 48You will need Visual Studio 2015 or higher, with the latest Update installed. 49 50You will also need the `CMake <http://www.cmake.org/>`_ build system since it 51generates the project files you will use to build with. 52 53If you would like to run the LLVM tests you will need `Python 54<http://www.python.org/>`_. Version 2.7 and newer are known to work. You will 55need `GnuWin32 <http://gnuwin32.sourceforge.net/>`_ tools, too. 56 57Do not install the LLVM directory tree into a path containing spaces (e.g. 58``C:\Documents and Settings\...``) as the configure step will fail. 59 60 61Getting Started 62=============== 63Here's the short story for getting up and running quickly with LLVM: 64 651. Read the documentation. 662. Seriously, read the documentation. 673. Remember that you were warned twice about reading the documentation. 684. Get the Source Code 69 70 * With the distributed files: 71 72 1. ``cd <where-you-want-llvm-to-live>`` 73 2. ``gunzip --stdout llvm-VERSION.tar.gz | tar -xvf -`` 74 (*or use WinZip*) 75 3. ``cd llvm`` 76 77 * With anonymous Subversion access: 78 79 *Note:* some regression tests require Unix-style line ending (``\n``). To 80 pass all regression tests, please add two lines *enable-auto-props = yes* 81 and *\* = svn:mime-type=application/octet-stream* to 82 ``C:\Users\<username>\AppData\Roaming\Subversion\config``. 83 84 1. ``cd <where-you-want-llvm-to-live>`` 85 2. ``svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm`` 86 3. ``cd llvm`` 87 885. Use `CMake <http://www.cmake.org/>`_ to generate up-to-date project files: 89 90 * Once CMake is installed then the simplest way is to just start the 91 CMake GUI, select the directory where you have LLVM extracted to, and 92 the default options should all be fine. One option you may really 93 want to change, regardless of anything else, might be the 94 ``CMAKE_INSTALL_PREFIX`` setting to select a directory to INSTALL to 95 once compiling is complete, although installation is not mandatory for 96 using LLVM. Another important option is ``LLVM_TARGETS_TO_BUILD``, 97 which controls the LLVM target architectures that are included on the 98 build. 99 * If CMake complains that it cannot find the compiler, make sure that 100 you have the Visual Studio C++ Tools installed, not just Visual Studio 101 itself (trying to create a C++ project in Visual Studio will generally 102 download the C++ tools if they haven't already been). 103 * See the :doc:`LLVM CMake guide <CMake>` for detailed information about 104 how to configure the LLVM build. 105 * CMake generates project files for all build types. To select a specific 106 build type, use the Configuration manager from the VS IDE or the 107 ``/property:Configuration`` command line option when using MSBuild. 108 * By default, the Visual Studio project files generated by CMake use the 109 32-bit toolset. If you are developing on a 64-bit version of Windows and 110 want to use the 64-bit toolset, pass the ``-Thost=x64`` flag when 111 generating the Visual Studio solution. This requires CMake 3.8.0 or later. 112 1136. Start Visual Studio 114 115 * In the directory you created the project files will have an ``llvm.sln`` 116 file, just double-click on that to open Visual Studio. 117 1187. Build the LLVM Suite: 119 120 * The projects may still be built individually, but to build them all do 121 not just select all of them in batch build (as some are meant as 122 configuration projects), but rather select and build just the 123 ``ALL_BUILD`` project to build everything, or the ``INSTALL`` project, 124 which first builds the ``ALL_BUILD`` project, then installs the LLVM 125 headers, libs, and other useful things to the directory set by the 126 ``CMAKE_INSTALL_PREFIX`` setting when you first configured CMake. 127 * The Fibonacci project is a sample program that uses the JIT. Modify the 128 project's debugging properties to provide a numeric command line argument 129 or run it from the command line. The program will print the 130 corresponding fibonacci value. 131 1328. Test LLVM in Visual Studio: 133 134 * If ``%PATH%`` does not contain GnuWin32, you may specify 135 ``LLVM_LIT_TOOLS_DIR`` on CMake for the path to GnuWin32. 136 * You can run LLVM tests by merely building the project "check". The test 137 results will be shown in the VS output window. 138 1399. Test LLVM on the command line: 140 141 * The LLVM tests can be run by changing directory to the llvm source 142 directory and running: 143 144 .. code-block:: bat 145 146 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 147 148 This example assumes that Python is in your PATH variable, you 149 have built a Win32 Debug version of llvm with a standard out of 150 line build. You should not see any unexpected failures, but will 151 see many unsupported tests and expected failures. 152 153 A specific test or test directory can be run with: 154 155 .. code-block:: bat 156 157 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 158 159 160An Example Using the LLVM Tool Chain 161==================================== 162 1631. First, create a simple C file, name it '``hello.c``': 164 165 .. code-block:: c 166 167 #include <stdio.h> 168 int main() { 169 printf("hello world\n"); 170 return 0; 171 } 172 1732. Next, compile the C file into an LLVM bitcode file: 174 175 .. code-block:: bat 176 177 C:\..> clang -c hello.c -emit-llvm -o hello.bc 178 179 This will create the result file ``hello.bc`` which is the LLVM bitcode 180 that corresponds the compiled program and the library facilities that 181 it required. You can execute this file directly using ``lli`` tool, 182 compile it to native assembly with the ``llc``, optimize or analyze it 183 further with the ``opt`` tool, etc. 184 185 Alternatively you can directly output an executable with clang with: 186 187 .. code-block:: bat 188 189 C:\..> clang hello.c -o hello.exe 190 191 The ``-o hello.exe`` is required because clang currently outputs ``a.out`` 192 when neither ``-o`` nor ``-c`` are given. 193 1943. Run the program using the just-in-time compiler: 195 196 .. code-block:: bat 197 198 C:\..> lli hello.bc 199 2004. Use the ``llvm-dis`` utility to take a look at the LLVM assembly code: 201 202 .. code-block:: bat 203 204 C:\..> llvm-dis < hello.bc | more 205 2065. Compile the program to object code using the LLC code generator: 207 208 .. code-block:: bat 209 210 C:\..> llc -filetype=obj hello.bc 211 2126. Link to binary using Microsoft link: 213 214 .. code-block:: bat 215 216 C:\..> link hello.obj -defaultlib:libcmt 217 2187. Execute the native code program: 219 220 .. code-block:: bat 221 222 C:\..> hello.exe 223 224 225Common Problems 226=============== 227If you are having problems building or using LLVM, or if you have any other 228general questions about LLVM, please consult the :doc:`Frequently Asked Questions 229<FAQ>` page. 230 231 232Links 233===== 234This document is just an **introduction** to how to use LLVM to do some simple 235things... there are many more interesting and complicated things that you can 236do that aren't documented here (but we'll gladly accept a patch if you want to 237write something up!). For more information about LLVM, check out: 238 239* `LLVM homepage <http://llvm.org/>`_ 240* `LLVM doxygen tree <http://llvm.org/doxygen/>`_ 241 242