3 1. Visual Studio 2013 is no longer supported
5 [As scheduled](https://github.com/KhronosGroup/glslang/blob/9eef54b2513ca6b40b47b07d24f453848b65c0df/README.md#planned-deprecationsremovals),
6 Microsoft Visual Studio 2013 is no longer officially supported. \
7 Please upgrade to at least Visual Studio 2015.
9 2. The versioning scheme is being improved, and you might notice some differences. This is currently WIP, but will be coming soon. See, for example, PR #2277.
11 3. If you get a new **compilation error due to a missing header**, it might be caused by this planned removal:
13 **SPIRV Folder, 1-May, 2020.** Glslang, when installed through CMake,
14 will install a `SPIRV` folder into `${CMAKE_INSTALL_INCLUDEDIR}`.
15 This `SPIRV` folder is being moved to `glslang/SPIRV`.
16 During the transition the `SPIRV` folder will be installed into both locations.
17 The old install of `SPIRV/` will be removed as a CMake install target no sooner than May 1, 2020.
20 If people are only using this location to get spirv.hpp, I recommend they get that from [SPIRV-Headers](https://github.com/KhronosGroup/SPIRV-Headers) instead.
22 [![appveyor status](https://ci.appveyor.com/api/projects/status/q6fi9cb0qnhkla68/branch/master?svg=true)](https://ci.appveyor.com/project/Khronoswebmaster/glslang/branch/master)
23 ![Continuous Deployment](https://github.com/KhronosGroup/glslang/actions/workflows/continuous_deployment.yml/badge.svg)
25 # Glslang Components and Status
27 There are several components:
29 ### Reference Validator and GLSL/ESSL -> AST Front End
31 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).
33 **Status**: Virtually complete, with results carrying similar weight as the specifications.
35 ### HLSL -> AST Front End
37 An HLSL front-end for translation of an approximation of HLSL to glslang's AST form.
39 **Status**: Partially complete. Semantics are not reference quality and input is not validated.
40 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.
42 See [issue 362](https://github.com/KhronosGroup/glslang/issues/362) and [issue 701](https://github.com/KhronosGroup/glslang/issues/701) for current status.
44 ### AST -> SPIR-V Back End
46 Translates glslang's AST to the Khronos-specified SPIR-V intermediate language.
48 **Status**: Virtually complete.
52 An API for getting reflection information from the AST, reflection types/variables/etc. from the HLL source (not the SPIR-V).
54 **Status**: There is a large amount of functionality present, but no specification/goal to measure completeness against. It is accurate for the input HLL and AST, but only approximate for what would later be emitted for SPIR-V.
56 ### Standalone Wrapper
58 `glslangValidator` is command-line tool for accessing the functionality above.
62 Tasks waiting to be done are documented as GitHub issues.
66 Also see the Khronos landing page for glslang as a reference front end:
68 https://www.khronos.org/opengles/sdk/tools/Reference-Compiler/
70 The above page, while not kept up to date, includes additional information regarding glslang as a reference validator.
74 ## Execution of Standalone Wrapper
76 To use the standalone binary form, execute `glslangValidator`, and it will print
77 a usage statement. Basic operation is to give it a file containing a shader,
78 and it will print out warnings/errors and optionally an AST.
80 The applied stage-specific rules are based on the file extension:
81 * `.vert` for a vertex shader
82 * `.tesc` for a tessellation control shader
83 * `.tese` for a tessellation evaluation shader
84 * `.geom` for a geometry shader
85 * `.frag` for a fragment shader
86 * `.comp` for a compute shader
88 There is also a non-shader extension
89 * `.conf` for a configuration file of limits, see usage statement for example
93 Instead of building manually, you can also download the binaries for your
94 platform directly from the [master-tot release][master-tot-release] on GitHub.
95 Those binaries are automatically uploaded by the buildbots after successful
96 testing and they always reflect the current top of the tree of the master
102 (For MSVS: use 2015 or later.)
103 * [CMake][cmake]: for generating compilation targets.
104 * make: _Linux_, ninja is an alternative, if configured.
105 * [Python 3.x][python]: for executing SPIRV-Tools scripts. (Optional if not using SPIRV-Tools and the 'External' subdirectory does not exist.)
106 * [bison][bison]: _optional_, but needed when changing the grammar (glslang.y).
107 * [googletest][googletest]: _optional_, but should use if making any changes to glslang.
111 The following steps assume a Bash shell. On Windows, that could be the Git Bash
112 shell or some other shell of your choosing.
114 #### 1) Check-Out this project
117 cd <parent of where you want glslang to be>
118 git clone https://github.com/KhronosGroup/glslang.git
121 #### 2) Check-Out External Projects
124 cd <the directory glslang was cloned to, "External" will be a subdirectory>
125 git clone https://github.com/google/googletest.git External/googletest
128 TEMPORARY NOTICE: additionally perform the following to avoid a current
129 breakage in googletest:
132 cd External/googletest
133 git checkout 0c400f67fcf305869c5fb113dd296eca266c9725
137 If you wish to assure that SPIR-V generated from HLSL is legal for Vulkan,
138 wish to invoke -Os to reduce SPIR-V size from HLSL or GLSL, or wish to run the
139 integrated test suite, install spirv-tools with this:
142 ./update_glslang_sources.py
147 Assume the source directory is `$SOURCE_DIR` and the build directory is
148 `$BUILD_DIR`. First ensure the build directory exists, then navigate to it:
155 For building on Linux:
158 cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="$(pwd)/install" $SOURCE_DIR
159 # "Release" (for CMAKE_BUILD_TYPE) could also be "Debug" or "RelWithDebInfo"
162 For building on Android:
164 cmake $SOURCE_DIR -G "Unix Makefiles" -DCMAKE_INSTALL_PREFIX="$(pwd)/install" -DANDROID_ABI=arm64-v8a -DCMAKE_BUILD_TYPE=Release -DANDROID_STL=c++_static -DANDROID_PLATFORM=android-24 -DCMAKE_SYSTEM_NAME=Android -DANDROID_TOOLCHAIN=clang -DANDROID_ARM_MODE=arm -DCMAKE_MAKE_PROGRAM=$ANDROID_NDK_ROOT/prebuilt/linux-x86_64/bin/make -DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK_ROOT/build/cmake/android.toolchain.cmake
165 # If on Windows will be -DCMAKE_MAKE_PROGRAM=%ANDROID_NDK_ROOT%\prebuilt\windows-x86_64\bin\make.exe
166 # -G is needed for building on Windows
167 # -DANDROID_ABI can also be armeabi-v7a for 32 bit
170 For building on Windows:
173 cmake $SOURCE_DIR -DCMAKE_INSTALL_PREFIX="$(pwd)/install"
174 # The CMAKE_INSTALL_PREFIX part is for testing (explained later).
177 The CMake GUI also works for Windows (version 3.4.1 tested).
179 Also, consider using `git config --global core.fileMode false` (or with `--local`) on Windows
180 to prevent the addition of execution permission on files.
182 #### 4) Build and Install
189 cmake --build . --config Release --target install
190 # "Release" (for --config) could also be "Debug", "MinSizeRel", or "RelWithDebInfo"
193 If using MSVC, after running CMake to configure, use the
194 Configuration Manager to check the `INSTALL` project.
198 glslang can also be built with the [GN build system](https://gn.googlesource.com/gn/).
200 #### 1) Install `depot_tools`
202 Download [depot_tools.zip](https://storage.googleapis.com/chrome-infra/depot_tools.zip),
203 extract to a directory, and add this directory to your `PATH`.
205 #### 2) Synchronize dependencies and generate build files
207 This only needs to be done once after updating `glslang`.
209 With the current directory set to your `glslang` checkout, type:
212 ./update_glslang_sources.py
213 gclient sync --gclientfile=standalone.gclient
219 With the current directory set to your `glslang` checkout, type:
226 ### If you need to change the GLSL grammar
228 The grammar in `glslang/MachineIndependent/glslang.y` has to be recompiled with
229 bison if it changes, the output files are committed to the repo to avoid every
230 developer needing to have bison configured to compile the project when grammar
231 changes are quite infrequent. For windows you can get binaries from
232 [GnuWin32][bison-gnu-win32].
234 The command to rebuild is:
237 m4 -P MachineIndependent/glslang.m4 > MachineIndependent/glslang.y
238 bison --defines=MachineIndependent/glslang_tab.cpp.h
239 -t MachineIndependent/glslang.y
240 -o MachineIndependent/glslang_tab.cpp
243 The above commands are also available in the bash script in `updateGrammar`,
244 when executed from the glslang subdirectory of the glslang repository.
245 With no arguments it builds the full grammar, and with a "web" argument,
246 the web grammar subset (see more about the web subset in the next section).
248 ### Building to WASM for the Web and Node
249 ### Building a standalone JS/WASM library for the Web and Node
251 Use the steps in [Build Steps](#build-steps), with the following notes/exceptions:
252 * `emsdk` needs to be present in your executable search path, *PATH* for
253 Bash-like environments:
254 + [Instructions located here](https://emscripten.org/docs/getting_started/downloads.html#sdk-download-and-install)
255 * Wrap cmake call: `emcmake cmake`
256 * Set `-DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF`.
257 * Set `-DENABLE_HLSL=OFF` if HLSL is not needed.
258 * For a standalone JS/WASM library, turn on `-DENABLE_GLSLANG_JS=ON`.
259 * For building a minimum-size web subset of core glslang:
260 + turn on `-DENABLE_GLSLANG_WEBMIN=ON` (disables HLSL)
261 + execute `updateGrammar web` from the glslang subdirectory
262 (or if using your own scripts, `m4` needs a `-DGLSLANG_WEB` argument)
263 + optionally, for GLSL compilation error messages, turn on
264 `-DENABLE_GLSLANG_WEBMIN_DEVEL=ON`
265 * To get a fully minimized build, make sure to use `brotli` to compress the .js
271 emcmake cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_GLSLANG_JS=ON \
272 -DENABLE_HLSL=OFF -DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF ..
275 ## Building glslang - Using vcpkg
277 You can download and install glslang using the [vcpkg](https://github.com/Microsoft/vcpkg) dependency manager:
279 git clone https://github.com/Microsoft/vcpkg.git
282 ./vcpkg integrate install
283 ./vcpkg install glslang
285 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.
289 Right now, there are two test harnesses existing in glslang: one is [Google
290 Test](gtests/), one is the [`runtests` script](Test/runtests). The former
291 runs unit tests and single-shader single-threaded integration tests, while
292 the latter runs multiple-shader linking tests and multi-threaded tests.
296 The [`runtests` script](Test/runtests) requires compiled binaries to be
297 installed into `$BUILD_DIR/install`. Please make sure you have supplied the
298 correct configuration to CMake (using `-DCMAKE_INSTALL_PREFIX`) when building;
299 otherwise, you may want to modify the path in the `runtests` script.
301 Running Google Test-backed tests:
310 ctest -C {Debug|Release|RelWithDebInfo|MinSizeRel}
312 # or, run the test binary directly
313 # (which gives more fine-grained control like filtering):
314 <dir-to-glslangtests-in-build-dir>/glslangtests
317 Running `runtests` script-backed tests:
320 cd $SOURCE_DIR/Test && ./runtests
323 If some tests fail with validation errors, there may be a mismatch between the
324 version of `spirv-val` on the system and the version of glslang. In this
325 case, it is necessary to run `update_glslang_sources.py`. See "Check-Out
326 External Projects" above for more details.
328 ### Contributing tests
330 Test results should always be included with a pull request that modifies
333 If you are writing unit tests, please use the Google Test framework and
334 place the tests under the `gtests/` directory.
336 Integration tests are placed in the `Test/` directory. It contains test input
337 and a subdirectory `baseResults/` that contains the expected results of the
338 tests. Both the tests and `baseResults/` are under source-code control.
340 Google Test runs those integration tests by reading the test input, compiling
341 them, and then compare against the expected results in `baseResults/`. The
342 integration tests to run via Google Test is registered in various
343 `gtests/*.FromFile.cpp` source files. `glslangtests` provides a command-line
344 option `--update-mode`, which, if supplied, will overwrite the golden files
345 under the `baseResults/` directory with real output from that invocation.
346 For more information, please check `gtests/` directory's
347 [README](gtests/README.md).
349 For the `runtests` script, it will generate current results in the
350 `localResults/` directory and `diff` them against the `baseResults/`.
351 When you want to update the tracked test results, they need to be
352 copied from `localResults/` to `baseResults/`. This can be done by
353 the `bump` shell script.
355 You can add your own private list of tests, not tracked publicly, by using
356 `localtestlist` to list non-tracked tests. This is automatically read
357 by `runtests` and included in the `diff` and `bump` process.
359 ## Programmatic Interfaces
361 Another piece of software can programmatically translate shaders to an AST
362 using one of two different interfaces:
363 * A new C++ class-oriented interface, or
364 * The original C functional interface
366 The `main()` in `StandAlone/StandAlone.cpp` shows examples using both styles.
368 ### C++ Class Interface (new, preferred)
370 This interface is in roughly the last 1/3 of `ShaderLang.h`. It is in the
371 glslang namespace and contains the following, here with suggested calls
372 for generating SPIR-V:
375 const char* GetEsslVersionString();
376 const char* GetGlslVersionString();
377 bool InitializeProcess();
378 void FinalizeProcess();
382 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientVulkan or EShClientOpenGL, 100);
383 setEnvClient(EShClientVulkan or EShClientOpenGL, EShTargetVulkan_1_0 or EShTargetVulkan_1_1 or EShTargetOpenGL_450);
384 setEnvTarget(EShTargetSpv, EShTargetSpv_1_0 or EShTargetSpv_1_3);
386 const char* getInfoLog();
391 const char* getInfoLog();
395 For just validating (not generating code), substitute these calls:
398 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientNone, 0);
399 setEnvClient(EShClientNone, 0);
400 setEnvTarget(EShTargetNone, 0);
403 See `ShaderLang.h` and the usage of it in `StandAlone/StandAlone.cpp` for more
404 details. There is a block comment giving more detail above the calls for
405 `setEnvInput, setEnvClient, and setEnvTarget`.
407 ### C Functional Interface (original)
409 This interface is in roughly the first 2/3 of `ShaderLang.h`, and referred to
410 as the `Sh*()` interface, as all the entry points start `Sh`.
412 The `Sh*()` interface takes a "compiler" call-back object, which it calls after
413 building call back that is passed the AST and can then execute a back end on it.
415 The following is a simplified resulting run-time call stack:
418 ShCompile(shader, compiler) -> compiler(AST) -> <back end>
421 In practice, `ShCompile()` takes shader strings, default version, and
422 warning/error and other options for controlling compilation.
424 ## Basic Internal Operation
426 * Initial lexical analysis is done by the preprocessor in
427 `MachineIndependent/Preprocessor`, and then refined by a GLSL scanner
428 in `MachineIndependent/Scan.cpp`. There is currently no use of flex.
430 * Code is parsed using bison on `MachineIndependent/glslang.y` with the
431 aid of a symbol table and an AST. The symbol table is not passed on to
432 the back-end; the intermediate representation stands on its own.
433 The tree is built by the grammar productions, many of which are
434 offloaded into `ParseHelper.cpp`, and by `Intermediate.cpp`.
436 * The intermediate representation is very high-level, and represented
437 as an in-memory tree. This serves to lose no information from the
438 original program, and to have efficient transfer of the result from
439 parsing to the back-end. In the AST, constants are propagated and
440 folded, and a very small amount of dead code is eliminated.
442 To aid linking and reflection, the last top-level branch in the AST
443 lists all global symbols.
445 * The primary algorithm of the back-end compiler is to traverse the
446 tree (high-level intermediate representation), and create an internal
447 object code representation. There is an example of how to do this
448 in `MachineIndependent/intermOut.cpp`.
450 * Reduction of the tree to a linear byte-code style low-level intermediate
451 representation is likely a good way to generate fully optimized code.
453 * There is currently some dead old-style linker-type code still lying around.
455 * Memory pool: parsing uses types derived from C++ `std` types, using a
456 custom allocator that puts them in a memory pool. This makes allocation
457 of individual container/contents just few cycles and deallocation free.
458 This pool is popped after the AST is made and processed.
460 The use is simple: if you are going to call `new`, there are three cases:
462 - the object comes from the pool (its base class has the macro
463 `POOL_ALLOCATOR_NEW_DELETE` in it) and you do not have to call `delete`
465 - it is a `TString`, in which case call `NewPoolTString()`, which gets
466 it from the pool, and there is no corresponding `delete`
468 - the object does not come from the pool, and you have to do normal
469 C++ memory management of what you `new`
471 * Features can be protected by version/extension/stage/profile:
472 See the comment in `glslang/MachineIndependent/Versions.cpp`.
474 [cmake]: https://cmake.org/
475 [python]: https://www.python.org/
476 [bison]: https://www.gnu.org/software/bison/
477 [googletest]: https://github.com/google/googletest
478 [bison-gnu-win32]: http://gnuwin32.sourceforge.net/packages/bison.htm
479 [master-tot-release]: https://github.com/KhronosGroup/glslang/releases/tag/master-tot