3 [![Build Status](https://travis-ci.org/KhronosGroup/glslang.svg?branch=master)](https://travis-ci.org/KhronosGroup/glslang)
4 [![Build status](https://ci.appveyor.com/api/projects/status/q6fi9cb0qnhkla68/branch/master?svg=true)](https://ci.appveyor.com/project/Khronoswebmaster/glslang/branch/master)
6 ## Planned Deprecations/Removals
8 1. **SPIRV Folder, 1-May, 2020.** Glslang, when installed through CMake,
9 will install a `SPIRV` folder into `${CMAKE_INSTALL_INCLUDEDIR}`.
10 This `SPIRV` folder is being moved to `glslang/SPIRV`.
11 During the transition the `SPIRV` folder will be installed into both locations.
12 The old install of `SPIRV/` will be removed as a CMake install target no sooner than May 1, 2020.
15 2. **Visual Studio 2013, 20-July, 2020.** Keeping code compiling for MS Visual Studio 2013 will no longer be
16 a goal as of July 20, 2020, the fifth anniversary of the release of Visual Studio 2015.
18 # Glslang Components and Status
20 There are several components:
22 **Reference Validator and GLSL/ESSL -> AST Front End.** An OpenGL GLSL and OpenGL|ES GLSL (ESSL) front-end for reference validation and translation of GLSL/ESSL into an internal abstract syntax tree (AST).
24 Status: Virtually complete, with results carrying similar weight as the specifications.
26 **HLSL -> AST Front End.** An HLSL front-end for translation of an approximation of HLSL to glslang's AST form.
28 Status: Partially complete. Semantics are not reference quality and input is not validated.
29 This is in contrast to the [DXC project](https://github.com/Microsoft/DirectXShaderCompiler), which receives a much larger investment and attempts to have definitive/reference-level semantics.
31 See [issue 362](https://github.com/KhronosGroup/glslang/issues/362) and [issue 701](https://github.com/KhronosGroup/glslang/issues/701) for current status.
33 **AST -> SPIR-V Back End.** Translates glslang's AST to the Khronos-specified SPIR-V intermediate language.
35 Status: Virtually complete.
37 **Standalone Wrapper.** `glslangValidator` is command-line tool for accessing the functionality above.
41 Tasks waiting to be done are documented as GitHub issues.
45 Also see the Khronos landing page for glslang as a reference front end:
47 https://www.khronos.org/opengles/sdk/tools/Reference-Compiler/
49 The above page, while not kept up to date, includes additional information regarding glslang as a reference validator.
53 ## Execution of Standalone Wrapper
55 To use the standalone binary form, execute `glslangValidator`, and it will print
56 a usage statement. Basic operation is to give it a file containing a shader,
57 and it will print out warnings/errors and optionally an AST.
59 The applied stage-specific rules are based on the file extension:
60 * `.vert` for a vertex shader
61 * `.tesc` for a tessellation control shader
62 * `.tese` for a tessellation evaluation shader
63 * `.geom` for a geometry shader
64 * `.frag` for a fragment shader
65 * `.comp` for a compute shader
67 There is also a non-shader extension
68 * `.conf` for a configuration file of limits, see usage statement for example
72 Instead of building manually, you can also download the binaries for your
73 platform directly from the [master-tot release][master-tot-release] on GitHub.
74 Those binaries are automatically uploaded by the buildbots after successful
75 testing and they always reflect the current top of the tree of the master
81 (For MSVS: 2015 is recommended, 2013 is fully supported/tested, and 2010 support is attempted, but not tested.)
82 * [CMake][cmake]: for generating compilation targets.
83 * make: _Linux_, ninja is an alternative, if configured.
84 * [Python 3.x][python]: for executing SPIRV-Tools scripts. (Optional if not using SPIRV-Tools and the 'External' subdirectory does not exist.)
85 * [bison][bison]: _optional_, but needed when changing the grammar (glslang.y).
86 * [googletest][googletest]: _optional_, but should use if making any changes to glslang.
90 The following steps assume a Bash shell. On Windows, that could be the Git Bash
91 shell or some other shell of your choosing.
93 #### 1) Check-Out this project
96 cd <parent of where you want glslang to be>
97 git clone https://github.com/KhronosGroup/glslang.git
100 #### 2) Check-Out External Projects
103 cd <the directory glslang was cloned to, "External" will be a subdirectory>
104 git clone https://github.com/google/googletest.git External/googletest
107 If you want to use googletest with Visual Studio 2013, you also need to check out an older version:
110 # to use googletest with Visual Studio 2013
111 cd External/googletest
112 git checkout 440527a61e1c91188195f7de212c63c77e8f0a45
116 If you wish to assure that SPIR-V generated from HLSL is legal for Vulkan,
117 wish to invoke -Os to reduce SPIR-V size from HLSL or GLSL, or wish to run the
118 integrated test suite, install spirv-tools with this:
121 ./update_glslang_sources.py
126 Assume the source directory is `$SOURCE_DIR` and the build directory is
127 `$BUILD_DIR`. First ensure the build directory exists, then navigate to it:
134 For building on Linux:
137 cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="$(pwd)/install" $SOURCE_DIR
138 # "Release" (for CMAKE_BUILD_TYPE) could also be "Debug" or "RelWithDebInfo"
141 For building on Windows:
144 cmake $SOURCE_DIR -DCMAKE_INSTALL_PREFIX="$(pwd)/install"
145 # The CMAKE_INSTALL_PREFIX part is for testing (explained later).
148 The CMake GUI also works for Windows (version 3.4.1 tested).
150 Also, consider using `git config --global core.fileMode false` (or with `--local`) on Windows
151 to prevent the addition of execution permission on files.
153 #### 4) Build and Install
160 cmake --build . --config Release --target install
161 # "Release" (for --config) could also be "Debug", "MinSizeRel", or "RelWithDebInfo"
164 If using MSVC, after running CMake to configure, use the
165 Configuration Manager to check the `INSTALL` project.
167 ### If you need to change the GLSL grammar
169 The grammar in `glslang/MachineIndependent/glslang.y` has to be recompiled with
170 bison if it changes, the output files are committed to the repo to avoid every
171 developer needing to have bison configured to compile the project when grammar
172 changes are quite infrequent. For windows you can get binaries from
173 [GnuWin32][bison-gnu-win32].
175 The command to rebuild is:
178 m4 -P MachineIndependent/glslang.m4 > MachineIndependent/glslang.y
179 bison --defines=MachineIndependent/glslang_tab.cpp.h
180 -t MachineIndependent/glslang.y
181 -o MachineIndependent/glslang_tab.cpp
184 The above commands are also available in the bash script in `updateGrammar`,
185 when executed from the glslang subdirectory of the glslang repository.
186 With no arguments it builds the full grammar, and with a "web" argument,
187 the web grammar subset (see more about the web subset in the next section).
189 ### Building to WASM for the Web and Node
191 Use the steps in [Build Steps](#build-steps), with the following notes/exceptions:
192 * For building the web subset of core glslang:
193 + execute `updateGrammar web` from the glslang subdirectory
194 (or if using your own scripts, `m4` needs a `-DGLSLANG_WEB` argument)
195 + set `-DENABLE_HLSL=OFF -DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF`
196 + turn on `-DENABLE_GLSLANG_JS=ON`
197 + optionally, for a minimum-size binary, turn on `-DENABLE_GLSLANG_WEBMIN=ON`
198 + optionally, for GLSL compilation error messages, turn on `-DENABLE_GLSLANG_WEB_DEVEL=ON`
199 * `emsdk` needs to be present in your executable search path, *PATH* for
200 Bash-like environments
201 + [Instructions located
202 here](https://emscripten.org/docs/getting_started/downloads.html#sdk-download-and-install)
203 * Wrap cmake call: `emcmake cmake`
204 * To get a fully minimized build, make sure to use `brotli` to compress the .js
210 emcmake cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_GLSLANG_WEB=ON \
211 -DENABLE_HLSL=OFF -DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF ..
214 ## Building glslang - Using vcpkg
216 You can download and install glslang using the [vcpkg](https://github.com/Microsoft/vcpkg) dependency manager:
218 git clone https://github.com/Microsoft/vcpkg.git
221 ./vcpkg integrate install
222 ./vcpkg install glslang
224 The glslang port in vcpkg is kept up to date by Microsoft team members and community contributors. If the version is out of date, please [create an issue or pull request](https://github.com/Microsoft/vcpkg) on the vcpkg repository.
228 Right now, there are two test harnesses existing in glslang: one is [Google
229 Test](gtests/), one is the [`runtests` script](Test/runtests). The former
230 runs unit tests and single-shader single-threaded integration tests, while
231 the latter runs multiple-shader linking tests and multi-threaded tests.
235 The [`runtests` script](Test/runtests) requires compiled binaries to be
236 installed into `$BUILD_DIR/install`. Please make sure you have supplied the
237 correct configuration to CMake (using `-DCMAKE_INSTALL_PREFIX`) when building;
238 otherwise, you may want to modify the path in the `runtests` script.
240 Running Google Test-backed tests:
249 ctest -C {Debug|Release|RelWithDebInfo|MinSizeRel}
251 # or, run the test binary directly
252 # (which gives more fine-grained control like filtering):
253 <dir-to-glslangtests-in-build-dir>/glslangtests
256 Running `runtests` script-backed tests:
259 cd $SOURCE_DIR/Test && ./runtests
262 If some tests fail with validation errors, there may be a mismatch between the
263 version of `spirv-val` on the system and the version of glslang. In this
264 case, it is necessary to run `update_glslang_sources.py`. See "Check-Out
265 External Projects" above for more details.
267 ### Contributing tests
269 Test results should always be included with a pull request that modifies
272 If you are writing unit tests, please use the Google Test framework and
273 place the tests under the `gtests/` directory.
275 Integration tests are placed in the `Test/` directory. It contains test input
276 and a subdirectory `baseResults/` that contains the expected results of the
277 tests. Both the tests and `baseResults/` are under source-code control.
279 Google Test runs those integration tests by reading the test input, compiling
280 them, and then compare against the expected results in `baseResults/`. The
281 integration tests to run via Google Test is registered in various
282 `gtests/*.FromFile.cpp` source files. `glslangtests` provides a command-line
283 option `--update-mode`, which, if supplied, will overwrite the golden files
284 under the `baseResults/` directory with real output from that invocation.
285 For more information, please check `gtests/` directory's
286 [README](gtests/README.md).
288 For the `runtests` script, it will generate current results in the
289 `localResults/` directory and `diff` them against the `baseResults/`.
290 When you want to update the tracked test results, they need to be
291 copied from `localResults/` to `baseResults/`. This can be done by
292 the `bump` shell script.
294 You can add your own private list of tests, not tracked publicly, by using
295 `localtestlist` to list non-tracked tests. This is automatically read
296 by `runtests` and included in the `diff` and `bump` process.
298 ## Programmatic Interfaces
300 Another piece of software can programmatically translate shaders to an AST
301 using one of two different interfaces:
302 * A new C++ class-oriented interface, or
303 * The original C functional interface
305 The `main()` in `StandAlone/StandAlone.cpp` shows examples using both styles.
307 ### C++ Class Interface (new, preferred)
309 This interface is in roughly the last 1/3 of `ShaderLang.h`. It is in the
310 glslang namespace and contains the following, here with suggested calls
311 for generating SPIR-V:
314 const char* GetEsslVersionString();
315 const char* GetGlslVersionString();
316 bool InitializeProcess();
317 void FinalizeProcess();
321 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientVulkan or EShClientOpenGL, 100);
322 setEnvClient(EShClientVulkan or EShClientOpenGL, EShTargetVulkan_1_0 or EShTargetVulkan_1_1 or EShTargetOpenGL_450);
323 setEnvTarget(EShTargetSpv, EShTargetSpv_1_0 or EShTargetSpv_1_3);
325 const char* getInfoLog();
330 const char* getInfoLog();
334 For just validating (not generating code), substitute these calls:
337 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientNone, 0);
338 setEnvClient(EShClientNone, 0);
339 setEnvTarget(EShTargetNone, 0);
342 See `ShaderLang.h` and the usage of it in `StandAlone/StandAlone.cpp` for more
343 details. There is a block comment giving more detail above the calls for
344 `setEnvInput, setEnvClient, and setEnvTarget`.
346 ### C Functional Interface (original)
348 This interface is in roughly the first 2/3 of `ShaderLang.h`, and referred to
349 as the `Sh*()` interface, as all the entry points start `Sh`.
351 The `Sh*()` interface takes a "compiler" call-back object, which it calls after
352 building call back that is passed the AST and can then execute a back end on it.
354 The following is a simplified resulting run-time call stack:
357 ShCompile(shader, compiler) -> compiler(AST) -> <back end>
360 In practice, `ShCompile()` takes shader strings, default version, and
361 warning/error and other options for controlling compilation.
363 ## Basic Internal Operation
365 * Initial lexical analysis is done by the preprocessor in
366 `MachineIndependent/Preprocessor`, and then refined by a GLSL scanner
367 in `MachineIndependent/Scan.cpp`. There is currently no use of flex.
369 * Code is parsed using bison on `MachineIndependent/glslang.y` with the
370 aid of a symbol table and an AST. The symbol table is not passed on to
371 the back-end; the intermediate representation stands on its own.
372 The tree is built by the grammar productions, many of which are
373 offloaded into `ParseHelper.cpp`, and by `Intermediate.cpp`.
375 * The intermediate representation is very high-level, and represented
376 as an in-memory tree. This serves to lose no information from the
377 original program, and to have efficient transfer of the result from
378 parsing to the back-end. In the AST, constants are propagated and
379 folded, and a very small amount of dead code is eliminated.
381 To aid linking and reflection, the last top-level branch in the AST
382 lists all global symbols.
384 * The primary algorithm of the back-end compiler is to traverse the
385 tree (high-level intermediate representation), and create an internal
386 object code representation. There is an example of how to do this
387 in `MachineIndependent/intermOut.cpp`.
389 * Reduction of the tree to a linear byte-code style low-level intermediate
390 representation is likely a good way to generate fully optimized code.
392 * There is currently some dead old-style linker-type code still lying around.
394 * Memory pool: parsing uses types derived from C++ `std` types, using a
395 custom allocator that puts them in a memory pool. This makes allocation
396 of individual container/contents just few cycles and deallocation free.
397 This pool is popped after the AST is made and processed.
399 The use is simple: if you are going to call `new`, there are three cases:
401 - the object comes from the pool (its base class has the macro
402 `POOL_ALLOCATOR_NEW_DELETE` in it) and you do not have to call `delete`
404 - it is a `TString`, in which case call `NewPoolTString()`, which gets
405 it from the pool, and there is no corresponding `delete`
407 - the object does not come from the pool, and you have to do normal
408 C++ memory management of what you `new`
410 * Features can be protected by version/extension/stage/profile:
411 See the comment in `glslang/MachineIndependent/Versions.cpp`.
413 [cmake]: https://cmake.org/
414 [python]: https://www.python.org/
415 [bison]: https://www.gnu.org/software/bison/
416 [googletest]: https://github.com/google/googletest
417 [bison-gnu-win32]: http://gnuwin32.sourceforge.net/packages/bison.htm
418 [master-tot-release]: https://github.com/KhronosGroup/glslang/releases/tag/master-tot