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.
34 1. GLSLang, when installed through CMake, will install a `SPIRV` folder into
35 `${CMAKE_INSTALL_INCLUDEDIR}`. This `SPIRV` folder is being moved to
36 `glslang/SPIRV`. During the transition the `SPIRV` folder will be installed into
37 both locations. The old install of `SPIRV/` will be removed as a CMake install
38 target no sooner then May 1, 2020. See issue #1964.
40 Execution of Standalone Wrapper
41 -------------------------------
43 To use the standalone binary form, execute `glslangValidator`, and it will print
44 a usage statement. Basic operation is to give it a file containing a shader,
45 and it will print out warnings/errors and optionally an AST.
47 The applied stage-specific rules are based on the file extension:
48 * `.vert` for a vertex shader
49 * `.tesc` for a tessellation control shader
50 * `.tese` for a tessellation evaluation shader
51 * `.geom` for a geometry shader
52 * `.frag` for a fragment shader
53 * `.comp` for a compute shader
55 There is also a non-shader extension
56 * `.conf` for a configuration file of limits, see usage statement for example
61 Instead of building manually, you can also download the binaries for your
62 platform directly from the [master-tot release][master-tot-release] on GitHub.
63 Those binaries are automatically uploaded by the buildbots after successful
64 testing and they always reflect the current top of the tree of the master
70 (For MSVS: 2015 is recommended, 2013 is fully supported/tested, and 2010 support is attempted, but not tested.)
71 * [CMake][cmake]: for generating compilation targets.
72 * make: _Linux_, ninja is an alternative, if configured.
73 * [Python 3.x][python]: for executing SPIRV-Tools scripts. (Optional if not using SPIRV-Tools and the 'External' subdirectory does not exist.)
74 * [bison][bison]: _optional_, but needed when changing the grammar (glslang.y).
75 * [googletest][googletest]: _optional_, but should use if making any changes to glslang.
79 The following steps assume a Bash shell. On Windows, that could be the Git Bash
80 shell or some other shell of your choosing.
82 #### 1) Check-Out this project
85 cd <parent of where you want glslang to be>
86 git clone https://github.com/KhronosGroup/glslang.git
89 #### 2) Check-Out External Projects
92 cd <the directory glslang was cloned to, "External" will be a subdirectory>
93 git clone https://github.com/google/googletest.git External/googletest
96 If you want to use googletest with Visual Studio 2013, you also need to check out an older version:
99 # to use googletest with Visual Studio 2013
100 cd External/googletest
101 git checkout 440527a61e1c91188195f7de212c63c77e8f0a45
105 If you wish to assure that SPIR-V generated from HLSL is legal for Vulkan,
106 wish to invoke -Os to reduce SPIR-V size from HLSL or GLSL, or wish to run the
107 integrated test suite, install spirv-tools with this:
110 ./update_glslang_sources.py
115 Assume the source directory is `$SOURCE_DIR` and the build directory is
116 `$BUILD_DIR`. First ensure the build directory exists, then navigate to it:
123 For building on Linux:
126 cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="$(pwd)/install" $SOURCE_DIR
127 # "Release" (for CMAKE_BUILD_TYPE) could also be "Debug" or "RelWithDebInfo"
130 For building on Windows:
133 cmake $SOURCE_DIR -DCMAKE_INSTALL_PREFIX="$(pwd)/install"
134 # The CMAKE_INSTALL_PREFIX part is for testing (explained later).
137 The CMake GUI also works for Windows (version 3.4.1 tested).
139 Also, consider using `git config --global core.fileMode false` (or with `--local`) on Windows
140 to prevent the addition of execution permission on files.
142 #### 4) Build and Install
149 cmake --build . --config Release --target install
150 # "Release" (for --config) could also be "Debug", "MinSizeRel", or "RelWithDebInfo"
153 If using MSVC, after running CMake to configure, use the
154 Configuration Manager to check the `INSTALL` project.
156 ### If you need to change the GLSL grammar
158 The grammar in `glslang/MachineIndependent/glslang.y` has to be recompiled with
159 bison if it changes, the output files are committed to the repo to avoid every
160 developer needing to have bison configured to compile the project when grammar
161 changes are quite infrequent. For windows you can get binaries from
162 [GnuWin32][bison-gnu-win32].
164 The command to rebuild is:
167 m4 -P MachineIndependent/glslang.m4 > MachineIndependent/glslang.y
168 bison --defines=MachineIndependent/glslang_tab.cpp.h
169 -t MachineIndependent/glslang.y
170 -o MachineIndependent/glslang_tab.cpp
173 The above commands are also available in the bash script in `updateGrammar`,
174 when executed from the glslang subdirectory of the glslang repository.
175 With no arguments it builds the full grammar, and with a "web" argument,
176 the web grammar subset (see more about the web subset in the next section).
178 ### Building to WASM for the Web and Node
180 Use the steps in [Build Steps](#build-steps), with the following notes/exceptions:
181 * For building the web subset of core glslang:
182 + execute `updateGrammar web` from the glslang subdirectory
183 (or if using your own scripts, `m4` needs a `-DGLSLANG_WEB` argument)
184 + set `-DENABLE_HLSL=OFF -DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF`
185 + turn on `-DENABLE_GLSLANG_WEB=ON`
186 + optionally, for GLSL compilation error messages, turn on `-DENABLE_GLSLANG_WEB_DEVEL=ON`
187 * `emsdk` needs to be present in your executable search path, *PATH* for
188 Bash-like enivironments
189 + [Instructions located
190 here](https://emscripten.org/docs/getting_started/downloads.html#sdk-download-and-install)
191 * Wrap cmake call: `emcmake cmake`
192 * To get a fully minimized build, make sure to use `brotli` to compress the .js
198 emcmake cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_GLSLANG_WEB=ON \
199 -DENABLE_HLSL=OFF -DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF ..
205 Right now, there are two test harnesses existing in glslang: one is [Google
206 Test](gtests/), one is the [`runtests` script](Test/runtests). The former
207 runs unit tests and single-shader single-threaded integration tests, while
208 the latter runs multiple-shader linking tests and multi-threaded tests.
212 The [`runtests` script](Test/runtests) requires compiled binaries to be
213 installed into `$BUILD_DIR/install`. Please make sure you have supplied the
214 correct configuration to CMake (using `-DCMAKE_INSTALL_PREFIX`) when building;
215 otherwise, you may want to modify the path in the `runtests` script.
217 Running Google Test-backed tests:
226 ctest -C {Debug|Release|RelWithDebInfo|MinSizeRel}
228 # or, run the test binary directly
229 # (which gives more fine-grained control like filtering):
230 <dir-to-glslangtests-in-build-dir>/glslangtests
233 Running `runtests` script-backed tests:
236 cd $SOURCE_DIR/Test && ./runtests
239 If some tests fail with validation errors, there may be a mismatch between the
240 version of `spirv-val` on the system and the version of glslang. In this
241 case, it is necessary to run `update_glslang_sources.py`. See "Check-Out
242 External Projects" above for more details.
244 ### Contributing tests
246 Test results should always be included with a pull request that modifies
249 If you are writing unit tests, please use the Google Test framework and
250 place the tests under the `gtests/` directory.
252 Integration tests are placed in the `Test/` directory. It contains test input
253 and a subdirectory `baseResults/` that contains the expected results of the
254 tests. Both the tests and `baseResults/` are under source-code control.
256 Google Test runs those integration tests by reading the test input, compiling
257 them, and then compare against the expected results in `baseResults/`. The
258 integration tests to run via Google Test is registered in various
259 `gtests/*.FromFile.cpp` source files. `glslangtests` provides a command-line
260 option `--update-mode`, which, if supplied, will overwrite the golden files
261 under the `baseResults/` directory with real output from that invocation.
262 For more information, please check `gtests/` directory's
263 [README](gtests/README.md).
265 For the `runtests` script, it will generate current results in the
266 `localResults/` directory and `diff` them against the `baseResults/`.
267 When you want to update the tracked test results, they need to be
268 copied from `localResults/` to `baseResults/`. This can be done by
269 the `bump` shell script.
271 You can add your own private list of tests, not tracked publicly, by using
272 `localtestlist` to list non-tracked tests. This is automatically read
273 by `runtests` and included in the `diff` and `bump` process.
275 Programmatic Interfaces
276 -----------------------
278 Another piece of software can programmatically translate shaders to an AST
279 using one of two different interfaces:
280 * A new C++ class-oriented interface, or
281 * The original C functional interface
283 The `main()` in `StandAlone/StandAlone.cpp` shows examples using both styles.
285 ### C++ Class Interface (new, preferred)
287 This interface is in roughly the last 1/3 of `ShaderLang.h`. It is in the
288 glslang namespace and contains the following, here with suggested calls
289 for generating SPIR-V:
292 const char* GetEsslVersionString();
293 const char* GetGlslVersionString();
294 bool InitializeProcess();
295 void FinalizeProcess();
299 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientVulkan or EShClientOpenGL, 100);
300 setEnvClient(EShClientVulkan or EShClientOpenGL, EShTargetVulkan_1_0 or EShTargetVulkan_1_1 or EShTargetOpenGL_450);
301 setEnvTarget(EShTargetSpv, EShTargetSpv_1_0 or EShTargetSpv_1_3);
303 const char* getInfoLog();
308 const char* getInfoLog();
312 For just validating (not generating code), subsitute these calls:
315 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientNone, 0);
316 setEnvClient(EShClientNone, 0);
317 setEnvTarget(EShTargetNone, 0);
320 See `ShaderLang.h` and the usage of it in `StandAlone/StandAlone.cpp` for more
321 details. There is a block comment giving more detail above the calls for
322 `setEnvInput, setEnvClient, and setEnvTarget`.
324 ### C Functional Interface (original)
326 This interface is in roughly the first 2/3 of `ShaderLang.h`, and referred to
327 as the `Sh*()` interface, as all the entry points start `Sh`.
329 The `Sh*()` interface takes a "compiler" call-back object, which it calls after
330 building call back that is passed the AST and can then execute a backend on it.
332 The following is a simplified resulting run-time call stack:
335 ShCompile(shader, compiler) -> compiler(AST) -> <back end>
338 In practice, `ShCompile()` takes shader strings, default version, and
339 warning/error and other options for controlling compilation.
341 Basic Internal Operation
342 ------------------------
344 * Initial lexical analysis is done by the preprocessor in
345 `MachineIndependent/Preprocessor`, and then refined by a GLSL scanner
346 in `MachineIndependent/Scan.cpp`. There is currently no use of flex.
348 * Code is parsed using bison on `MachineIndependent/glslang.y` with the
349 aid of a symbol table and an AST. The symbol table is not passed on to
350 the back-end; the intermediate representation stands on its own.
351 The tree is built by the grammar productions, many of which are
352 offloaded into `ParseHelper.cpp`, and by `Intermediate.cpp`.
354 * The intermediate representation is very high-level, and represented
355 as an in-memory tree. This serves to lose no information from the
356 original program, and to have efficient transfer of the result from
357 parsing to the back-end. In the AST, constants are propogated and
358 folded, and a very small amount of dead code is eliminated.
360 To aid linking and reflection, the last top-level branch in the AST
361 lists all global symbols.
363 * The primary algorithm of the back-end compiler is to traverse the
364 tree (high-level intermediate representation), and create an internal
365 object code representation. There is an example of how to do this
366 in `MachineIndependent/intermOut.cpp`.
368 * Reduction of the tree to a linear byte-code style low-level intermediate
369 representation is likely a good way to generate fully optimized code.
371 * There is currently some dead old-style linker-type code still lying around.
373 * Memory pool: parsing uses types derived from C++ `std` types, using a
374 custom allocator that puts them in a memory pool. This makes allocation
375 of individual container/contents just few cycles and deallocation free.
376 This pool is popped after the AST is made and processed.
378 The use is simple: if you are going to call `new`, there are three cases:
380 - the object comes from the pool (its base class has the macro
381 `POOL_ALLOCATOR_NEW_DELETE` in it) and you do not have to call `delete`
383 - it is a `TString`, in which case call `NewPoolTString()`, which gets
384 it from the pool, and there is no corresponding `delete`
386 - the object does not come from the pool, and you have to do normal
387 C++ memory management of what you `new`
390 [cmake]: https://cmake.org/
391 [python]: https://www.python.org/
392 [bison]: https://www.gnu.org/software/bison/
393 [googletest]: https://github.com/google/googletest
394 [bison-gnu-win32]: http://gnuwin32.sourceforge.net/packages/bison.htm
395 [master-tot-release]: https://github.com/KhronosGroup/glslang/releases/tag/master-tot