1 Also see the Khronos landing page for glslang as a reference front end:
3 https://www.khronos.org/opengles/sdk/tools/Reference-Compiler/
5 The above page includes where to get binaries, and is kept up to date
6 regarding the feature level of glslang.
11 [![Build Status](https://travis-ci.org/KhronosGroup/glslang.svg?branch=master)](https://travis-ci.org/KhronosGroup/glslang)
12 [![Build status](https://ci.appveyor.com/api/projects/status/q6fi9cb0qnhkla68/branch/master?svg=true)](https://ci.appveyor.com/project/Khronoswebmaster/glslang/branch/master)
14 An OpenGL and OpenGL ES shader front end and validator.
16 There are several components:
18 1. A GLSL/ESSL front-end for reference validation and translation of GLSL/ESSL into an AST.
20 2. An HLSL front-end for translation of a broad generic HLL into the AST. See [issue 362](https://github.com/KhronosGroup/glslang/issues/362) and [issue 701](https://github.com/KhronosGroup/glslang/issues/701) for current status.
22 3. A SPIR-V back end for translating the AST to SPIR-V.
24 4. A standalone wrapper, `glslangValidator`, that can be used as a command-line tool for the above.
26 How to add a feature protected by a version/extension/stage/profile: See the
27 comment in `glslang/MachineIndependent/Versions.cpp`.
29 Tasks waiting to be done are documented as GitHub issues.
31 Execution of Standalone Wrapper
32 -------------------------------
34 To use the standalone binary form, execute `glslangValidator`, and it will print
35 a usage statement. Basic operation is to give it a file containing a shader,
36 and it will print out warnings/errors and optionally an AST.
38 The applied stage-specific rules are based on the file extension:
39 * `.vert` for a vertex shader
40 * `.tesc` for a tessellation control shader
41 * `.tese` for a tessellation evaluation shader
42 * `.geom` for a geometry shader
43 * `.frag` for a fragment shader
44 * `.comp` for a compute shader
46 There is also a non-shader extension
47 * `.conf` for a configuration file of limits, see usage statement for example
52 Instead of building manually, you can also download the binaries for your
53 platform directly from the [master-tot release][master-tot-release] on GitHub.
54 Those binaries are automatically uploaded by the buildbots after successful
55 testing and they always reflect the current top of the tree of the master
61 (For MSVS: 2015 is recommended, 2013 is fully supported/tested, and 2010 support is attempted, but not tested.)
62 * [CMake][cmake]: for generating compilation targets.
63 * make: _Linux_, ninja is an alternative, if configured.
64 * [Python 3.x][python]: for executing SPIRV-Tools scripts. (Optional if not using SPIRV-Tools and the 'External' subdirectory does not exist.)
65 * [bison][bison]: _optional_, but needed when changing the grammar (glslang.y).
66 * [googletest][googletest]: _optional_, but should use if making any changes to glslang.
70 The following steps assume a Bash shell. On Windows, that could be the Git Bash
71 shell or some other shell of your choosing.
73 #### 1) Check-Out this project
76 cd <parent of where you want glslang to be>
77 git clone https://github.com/KhronosGroup/glslang.git
80 #### 2) Check-Out External Projects
83 cd <the directory glslang was cloned to, "External" will be a subdirectory>
84 git clone https://github.com/google/googletest.git External/googletest
87 If you want to use googletest with Visual Studio 2013, you also need to check out an older version:
90 # to use googletest with Visual Studio 2013
91 cd External/googletest
92 git checkout 440527a61e1c91188195f7de212c63c77e8f0a45
96 If you wish to assure that SPIR-V generated from HLSL is legal for Vulkan,
97 or wish to invoke -Os to reduce SPIR-V size from HLSL or GLSL, install
98 spirv-tools with this:
101 ./update_glslang_sources.py
106 Assume the source directory is `$SOURCE_DIR` and the build directory is
107 `$BUILD_DIR`. First ensure the build directory exists, then navigate to it:
114 For building on Linux:
117 cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="$(pwd)/install" $SOURCE_DIR
118 # "Release" (for CMAKE_BUILD_TYPE) could also be "Debug" or "RelWithDebInfo"
121 For building on Windows:
124 cmake $SOURCE_DIR -DCMAKE_INSTALL_PREFIX="$(pwd)/install"
125 # The CMAKE_INSTALL_PREFIX part is for testing (explained later).
128 The CMake GUI also works for Windows (version 3.4.1 tested).
130 Also, consider using `git config --global core.fileMode false` (or with `--local`) on Windows
131 to prevent the addition of execution permission on files.
133 #### 4) Build and Install
140 cmake --build . --config Release --target install
141 # "Release" (for --config) could also be "Debug", "MinSizeRel", or "RelWithDebInfo"
144 If using MSVC, after running CMake to configure, use the
145 Configuration Manager to check the `INSTALL` project.
147 ### If you need to change the GLSL grammar
149 The grammar in `glslang/MachineIndependent/glslang.y` has to be recompiled with
150 bison if it changes, the output files are committed to the repo to avoid every
151 developer needing to have bison configured to compile the project when grammar
152 changes are quite infrequent. For windows you can get binaries from
153 [GnuWin32][bison-gnu-win32].
155 The command to rebuild is:
158 m4 -P MachineIndependent/glslang.m4 > MachineIndependent/glslang.y
159 bison --defines=MachineIndependent/glslang_tab.cpp.h
160 -t MachineIndependent/glslang.y
161 -o MachineIndependent/glslang_tab.cpp
164 The above commands are also available in the bash script in `updateGrammar`,
165 when executed from the glslang subdirectory of the glslang repository.
166 With no arguments it builds the full grammar, and with a "web" argument,
167 the web grammar subset (see more about the web subset in the next section).
169 ### WASM for the the Web
171 Use the steps in [Build Steps](#build-steps), which following notes/exceptions:
172 * For building the web subset of core glslang:
173 + `m4` also needs a `-DGLSLANG_WEB` argument, or simply execute `updateGrammar web` from the glslang subdirectory
174 + turn off the CMAKE options for `BUILD_TESTING`, `ENABLE_OPT`, and `INSTALL_GTEST`,
175 while turning on `ENABLE_GLSLANG_WEB`
176 * `emsdk` needs to be present in your executable search path, *PATH* for
177 Bash-like enivironments
178 + Instructions located
179 [here](https://emscripten.org/docs/getting_started/downloads.html#sdk-download-and-install)
180 * Do not checkout SPIRV-Tools into `External`
181 + Does not work correctly with emscripten out of the box and we don't want it
182 in the build anyway. *TBD* Have build ignore SPIRV-Tools for web build
183 * Wrap call to `cmake` using `emconfigure` with ENABLE_GLSLANG_WEB=ON:
184 + e.g. For Linux, `emconfigure cmake -DCMAKE_BUILD_TYPE=Release
185 -DENABLE_GLSLANG_WEB=ON -DCMAKE_INSTALL_PREFIX="$(pwd)/install" ..`
186 * To get a 'true' minimized build, make sure to use `brotli` to compress the .js
192 Right now, there are two test harnesses existing in glslang: one is [Google
193 Test](gtests/), one is the [`runtests` script](Test/runtests). The former
194 runs unit tests and single-shader single-threaded integration tests, while
195 the latter runs multiple-shader linking tests and multi-threaded tests.
199 The [`runtests` script](Test/runtests) requires compiled binaries to be
200 installed into `$BUILD_DIR/install`. Please make sure you have supplied the
201 correct configuration to CMake (using `-DCMAKE_INSTALL_PREFIX`) when building;
202 otherwise, you may want to modify the path in the `runtests` script.
204 Running Google Test-backed tests:
213 ctest -C {Debug|Release|RelWithDebInfo|MinSizeRel}
215 # or, run the test binary directly
216 # (which gives more fine-grained control like filtering):
217 <dir-to-glslangtests-in-build-dir>/glslangtests
220 Running `runtests` script-backed tests:
223 cd $SOURCE_DIR/Test && ./runtests
226 ### Contributing tests
228 Test results should always be included with a pull request that modifies
231 If you are writing unit tests, please use the Google Test framework and
232 place the tests under the `gtests/` directory.
234 Integration tests are placed in the `Test/` directory. It contains test input
235 and a subdirectory `baseResults/` that contains the expected results of the
236 tests. Both the tests and `baseResults/` are under source-code control.
238 Google Test runs those integration tests by reading the test input, compiling
239 them, and then compare against the expected results in `baseResults/`. The
240 integration tests to run via Google Test is registered in various
241 `gtests/*.FromFile.cpp` source files. `glslangtests` provides a command-line
242 option `--update-mode`, which, if supplied, will overwrite the golden files
243 under the `baseResults/` directory with real output from that invocation.
244 For more information, please check `gtests/` directory's
245 [README](gtests/README.md).
247 For the `runtests` script, it will generate current results in the
248 `localResults/` directory and `diff` them against the `baseResults/`.
249 When you want to update the tracked test results, they need to be
250 copied from `localResults/` to `baseResults/`. This can be done by
251 the `bump` shell script.
253 You can add your own private list of tests, not tracked publicly, by using
254 `localtestlist` to list non-tracked tests. This is automatically read
255 by `runtests` and included in the `diff` and `bump` process.
257 Programmatic Interfaces
258 -----------------------
260 Another piece of software can programmatically translate shaders to an AST
261 using one of two different interfaces:
262 * A new C++ class-oriented interface, or
263 * The original C functional interface
265 The `main()` in `StandAlone/StandAlone.cpp` shows examples using both styles.
267 ### C++ Class Interface (new, preferred)
269 This interface is in roughly the last 1/3 of `ShaderLang.h`. It is in the
270 glslang namespace and contains the following.
273 const char* GetEsslVersionString();
274 const char* GetGlslVersionString();
275 bool InitializeProcess();
276 void FinalizeProcess();
280 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientVulkan or EShClientOpenGL, 100);
281 setEnvClient(EShClientVulkan or EShClientOpenGL, EShTargetVulkan_1_0 or EShTargetVulkan_1_1 or EShTargetOpenGL_450);
282 setEnvTarget(EShTargetSpv, EShTargetSpv_1_0 or EShTargetSpv_1_3);
284 const char* getInfoLog();
289 const char* getInfoLog();
293 See `ShaderLang.h` and the usage of it in `StandAlone/StandAlone.cpp` for more
296 ### C Functional Interface (orignal)
298 This interface is in roughly the first 2/3 of `ShaderLang.h`, and referred to
299 as the `Sh*()` interface, as all the entry points start `Sh`.
301 The `Sh*()` interface takes a "compiler" call-back object, which it calls after
302 building call back that is passed the AST and can then execute a backend on it.
304 The following is a simplified resulting run-time call stack:
307 ShCompile(shader, compiler) -> compiler(AST) -> <back end>
310 In practice, `ShCompile()` takes shader strings, default version, and
311 warning/error and other options for controlling compilation.
313 Basic Internal Operation
314 ------------------------
316 * Initial lexical analysis is done by the preprocessor in
317 `MachineIndependent/Preprocessor`, and then refined by a GLSL scanner
318 in `MachineIndependent/Scan.cpp`. There is currently no use of flex.
320 * Code is parsed using bison on `MachineIndependent/glslang.y` with the
321 aid of a symbol table and an AST. The symbol table is not passed on to
322 the back-end; the intermediate representation stands on its own.
323 The tree is built by the grammar productions, many of which are
324 offloaded into `ParseHelper.cpp`, and by `Intermediate.cpp`.
326 * The intermediate representation is very high-level, and represented
327 as an in-memory tree. This serves to lose no information from the
328 original program, and to have efficient transfer of the result from
329 parsing to the back-end. In the AST, constants are propogated and
330 folded, and a very small amount of dead code is eliminated.
332 To aid linking and reflection, the last top-level branch in the AST
333 lists all global symbols.
335 * The primary algorithm of the back-end compiler is to traverse the
336 tree (high-level intermediate representation), and create an internal
337 object code representation. There is an example of how to do this
338 in `MachineIndependent/intermOut.cpp`.
340 * Reduction of the tree to a linear byte-code style low-level intermediate
341 representation is likely a good way to generate fully optimized code.
343 * There is currently some dead old-style linker-type code still lying around.
345 * Memory pool: parsing uses types derived from C++ `std` types, using a
346 custom allocator that puts them in a memory pool. This makes allocation
347 of individual container/contents just few cycles and deallocation free.
348 This pool is popped after the AST is made and processed.
350 The use is simple: if you are going to call `new`, there are three cases:
352 - the object comes from the pool (its base class has the macro
353 `POOL_ALLOCATOR_NEW_DELETE` in it) and you do not have to call `delete`
355 - it is a `TString`, in which case call `NewPoolTString()`, which gets
356 it from the pool, and there is no corresponding `delete`
358 - the object does not come from the pool, and you have to do normal
359 C++ memory management of what you `new`
362 [cmake]: https://cmake.org/
363 [python]: https://www.python.org/
364 [bison]: https://www.gnu.org/software/bison/
365 [googletest]: https://github.com/google/googletest
366 [bison-gnu-win32]: http://gnuwin32.sourceforge.net/packages/bison.htm
367 [master-tot-release]: https://github.com/KhronosGroup/glslang/releases/tag/master-tot