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 Integration](https://github.com/KhronosGroup/glslang/actions/workflows/continuous_integration.yml/badge.svg)
24 ![Continuous Deployment](https://github.com/KhronosGroup/glslang/actions/workflows/continuous_deployment.yml/badge.svg)
26 # Glslang Components and Status
28 There are several components:
30 ### Reference Validator and GLSL/ESSL -> AST Front End
32 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).
34 **Status**: Virtually complete, with results carrying similar weight as the specifications.
36 ### HLSL -> AST Front End
38 An HLSL front-end for translation of an approximation of HLSL to glslang's AST form.
40 **Status**: Partially complete. Semantics are not reference quality and input is not validated.
41 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.
43 See [issue 362](https://github.com/KhronosGroup/glslang/issues/362) and [issue 701](https://github.com/KhronosGroup/glslang/issues/701) for current status.
45 ### AST -> SPIR-V Back End
47 Translates glslang's AST to the Khronos-specified SPIR-V intermediate language.
49 **Status**: Virtually complete.
53 An API for getting reflection information from the AST, reflection types/variables/etc. from the HLL source (not the SPIR-V).
55 **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.
57 ### Standalone Wrapper
59 `glslangValidator` is command-line tool for accessing the functionality above.
63 Tasks waiting to be done are documented as GitHub issues.
67 Also see the Khronos landing page for glslang as a reference front end:
69 https://www.khronos.org/opengles/sdk/tools/Reference-Compiler/
71 The above page, while not kept up to date, includes additional information regarding glslang as a reference validator.
75 ## Execution of Standalone Wrapper
77 To use the standalone binary form, execute `glslangValidator`, and it will print
78 a usage statement. Basic operation is to give it a file containing a shader,
79 and it will print out warnings/errors and optionally an AST.
81 The applied stage-specific rules are based on the file extension:
82 * `.vert` for a vertex shader
83 * `.tesc` for a tessellation control shader
84 * `.tese` for a tessellation evaluation shader
85 * `.geom` for a geometry shader
86 * `.frag` for a fragment shader
87 * `.comp` for a compute shader
89 There is also a non-shader extension
90 * `.conf` for a configuration file of limits, see usage statement for example
94 Instead of building manually, you can also download the binaries for your
95 platform directly from the [master-tot release][master-tot-release] on GitHub.
96 Those binaries are automatically uploaded by the buildbots after successful
97 testing and they always reflect the current top of the tree of the master
103 (For MSVS: use 2015 or later.)
104 * [CMake][cmake]: for generating compilation targets.
105 * make: _Linux_, ninja is an alternative, if configured.
106 * [Python 3.x][python]: for executing SPIRV-Tools scripts. (Optional if not using SPIRV-Tools and the 'External' subdirectory does not exist.)
107 * [bison][bison]: _optional_, but needed when changing the grammar (glslang.y).
108 * [googletest][googletest]: _optional_, but should use if making any changes to glslang.
112 The following steps assume a Bash shell. On Windows, that could be the Git Bash
113 shell or some other shell of your choosing.
115 #### 1) Check-Out this project
118 cd <parent of where you want glslang to be>
119 git clone https://github.com/KhronosGroup/glslang.git
122 #### 2) Check-Out External Projects
125 cd <the directory glslang was cloned to, "External" will be a subdirectory>
126 git clone https://github.com/google/googletest.git External/googletest
129 TEMPORARY NOTICE: additionally perform the following to avoid a current
130 breakage in googletest:
133 cd External/googletest
134 git checkout 0c400f67fcf305869c5fb113dd296eca266c9725
138 If you wish to assure that SPIR-V generated from HLSL is legal for Vulkan,
139 wish to invoke -Os to reduce SPIR-V size from HLSL or GLSL, or wish to run the
140 integrated test suite, install spirv-tools with this:
143 ./update_glslang_sources.py
148 Assume the source directory is `$SOURCE_DIR` and the build directory is
149 `$BUILD_DIR`. First ensure the build directory exists, then navigate to it:
156 For building on Linux:
159 cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="$(pwd)/install" $SOURCE_DIR
160 # "Release" (for CMAKE_BUILD_TYPE) could also be "Debug" or "RelWithDebInfo"
163 For building on Android:
165 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
166 # If on Windows will be -DCMAKE_MAKE_PROGRAM=%ANDROID_NDK_ROOT%\prebuilt\windows-x86_64\bin\make.exe
167 # -G is needed for building on Windows
168 # -DANDROID_ABI can also be armeabi-v7a for 32 bit
171 For building on Windows:
174 cmake $SOURCE_DIR -DCMAKE_INSTALL_PREFIX="$(pwd)/install"
175 # The CMAKE_INSTALL_PREFIX part is for testing (explained later).
178 The CMake GUI also works for Windows (version 3.4.1 tested).
180 Also, consider using `git config --global core.fileMode false` (or with `--local`) on Windows
181 to prevent the addition of execution permission on files.
183 #### 4) Build and Install
190 cmake --build . --config Release --target install
191 # "Release" (for --config) could also be "Debug", "MinSizeRel", or "RelWithDebInfo"
194 If using MSVC, after running CMake to configure, use the
195 Configuration Manager to check the `INSTALL` project.
199 glslang can also be built with the [GN build system](https://gn.googlesource.com/gn/).
201 #### 1) Install `depot_tools`
203 Download [depot_tools.zip](https://storage.googleapis.com/chrome-infra/depot_tools.zip),
204 extract to a directory, and add this directory to your `PATH`.
206 #### 2) Synchronize dependencies and generate build files
208 This only needs to be done once after updating `glslang`.
210 With the current directory set to your `glslang` checkout, type:
213 ./update_glslang_sources.py
214 gclient sync --gclientfile=standalone.gclient
220 With the current directory set to your `glslang` checkout, type:
227 ### If you need to change the GLSL grammar
229 The grammar in `glslang/MachineIndependent/glslang.y` has to be recompiled with
230 bison if it changes, the output files are committed to the repo to avoid every
231 developer needing to have bison configured to compile the project when grammar
232 changes are quite infrequent. For windows you can get binaries from
233 [GnuWin32][bison-gnu-win32].
235 The command to rebuild is:
238 m4 -P MachineIndependent/glslang.m4 > MachineIndependent/glslang.y
239 bison --defines=MachineIndependent/glslang_tab.cpp.h
240 -t MachineIndependent/glslang.y
241 -o MachineIndependent/glslang_tab.cpp
244 The above commands are also available in the bash script in `updateGrammar`,
245 when executed from the glslang subdirectory of the glslang repository.
246 With no arguments it builds the full grammar, and with a "web" argument,
247 the web grammar subset (see more about the web subset in the next section).
249 ### Building to WASM for the Web and Node
250 ### Building a standalone JS/WASM library for the Web and Node
252 Use the steps in [Build Steps](#build-steps), with the following notes/exceptions:
253 * `emsdk` needs to be present in your executable search path, *PATH* for
254 Bash-like environments:
255 + [Instructions located here](https://emscripten.org/docs/getting_started/downloads.html#sdk-download-and-install)
256 * Wrap cmake call: `emcmake cmake`
257 * Set `-DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF`.
258 * Set `-DENABLE_HLSL=OFF` if HLSL is not needed.
259 * For a standalone JS/WASM library, turn on `-DENABLE_GLSLANG_JS=ON`.
260 * For building a minimum-size web subset of core glslang:
261 + turn on `-DENABLE_GLSLANG_WEBMIN=ON` (disables HLSL)
262 + execute `updateGrammar web` from the glslang subdirectory
263 (or if using your own scripts, `m4` needs a `-DGLSLANG_WEB` argument)
264 + optionally, for GLSL compilation error messages, turn on
265 `-DENABLE_GLSLANG_WEBMIN_DEVEL=ON`
266 * To get a fully minimized build, make sure to use `brotli` to compress the .js
272 emcmake cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_GLSLANG_JS=ON \
273 -DENABLE_HLSL=OFF -DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF ..
276 ## Building glslang - Using vcpkg
278 You can download and install glslang using the [vcpkg](https://github.com/Microsoft/vcpkg) dependency manager:
280 git clone https://github.com/Microsoft/vcpkg.git
283 ./vcpkg integrate install
284 ./vcpkg install glslang
286 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.
290 Right now, there are two test harnesses existing in glslang: one is [Google
291 Test](gtests/), one is the [`runtests` script](Test/runtests). The former
292 runs unit tests and single-shader single-threaded integration tests, while
293 the latter runs multiple-shader linking tests and multi-threaded tests.
297 The [`runtests` script](Test/runtests) requires compiled binaries to be
298 installed into `$BUILD_DIR/install`. Please make sure you have supplied the
299 correct configuration to CMake (using `-DCMAKE_INSTALL_PREFIX`) when building;
300 otherwise, you may want to modify the path in the `runtests` script.
302 Running Google Test-backed tests:
311 ctest -C {Debug|Release|RelWithDebInfo|MinSizeRel}
313 # or, run the test binary directly
314 # (which gives more fine-grained control like filtering):
315 <dir-to-glslangtests-in-build-dir>/glslangtests
318 Running `runtests` script-backed tests:
321 cd $SOURCE_DIR/Test && ./runtests
324 If some tests fail with validation errors, there may be a mismatch between the
325 version of `spirv-val` on the system and the version of glslang. In this
326 case, it is necessary to run `update_glslang_sources.py`. See "Check-Out
327 External Projects" above for more details.
329 ### Contributing tests
331 Test results should always be included with a pull request that modifies
334 If you are writing unit tests, please use the Google Test framework and
335 place the tests under the `gtests/` directory.
337 Integration tests are placed in the `Test/` directory. It contains test input
338 and a subdirectory `baseResults/` that contains the expected results of the
339 tests. Both the tests and `baseResults/` are under source-code control.
341 Google Test runs those integration tests by reading the test input, compiling
342 them, and then compare against the expected results in `baseResults/`. The
343 integration tests to run via Google Test is registered in various
344 `gtests/*.FromFile.cpp` source files. `glslangtests` provides a command-line
345 option `--update-mode`, which, if supplied, will overwrite the golden files
346 under the `baseResults/` directory with real output from that invocation.
347 For more information, please check `gtests/` directory's
348 [README](gtests/README.md).
350 For the `runtests` script, it will generate current results in the
351 `localResults/` directory and `diff` them against the `baseResults/`.
352 When you want to update the tracked test results, they need to be
353 copied from `localResults/` to `baseResults/`. This can be done by
354 the `bump` shell script.
356 You can add your own private list of tests, not tracked publicly, by using
357 `localtestlist` to list non-tracked tests. This is automatically read
358 by `runtests` and included in the `diff` and `bump` process.
360 ## Programmatic Interfaces
362 Another piece of software can programmatically translate shaders to an AST
363 using one of two different interfaces:
364 * A new C++ class-oriented interface, or
365 * The original C functional interface
367 The `main()` in `StandAlone/StandAlone.cpp` shows examples using both styles.
369 ### C++ Class Interface (new, preferred)
371 This interface is in roughly the last 1/3 of `ShaderLang.h`. It is in the
372 glslang namespace and contains the following, here with suggested calls
373 for generating SPIR-V:
376 const char* GetEsslVersionString();
377 const char* GetGlslVersionString();
378 bool InitializeProcess();
379 void FinalizeProcess();
383 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientVulkan or EShClientOpenGL, 100);
384 setEnvClient(EShClientVulkan or EShClientOpenGL, EShTargetVulkan_1_0 or EShTargetVulkan_1_1 or EShTargetOpenGL_450);
385 setEnvTarget(EShTargetSpv, EShTargetSpv_1_0 or EShTargetSpv_1_3);
387 const char* getInfoLog();
392 const char* getInfoLog();
396 For just validating (not generating code), substitute these calls:
399 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientNone, 0);
400 setEnvClient(EShClientNone, 0);
401 setEnvTarget(EShTargetNone, 0);
404 See `ShaderLang.h` and the usage of it in `StandAlone/StandAlone.cpp` for more
405 details. There is a block comment giving more detail above the calls for
406 `setEnvInput, setEnvClient, and setEnvTarget`.
408 ### C Functional Interface (original)
410 This interface is in roughly the first 2/3 of `ShaderLang.h`, and referred to
411 as the `Sh*()` interface, as all the entry points start `Sh`.
413 The `Sh*()` interface takes a "compiler" call-back object, which it calls after
414 building call back that is passed the AST and can then execute a back end on it.
416 The following is a simplified resulting run-time call stack:
419 ShCompile(shader, compiler) -> compiler(AST) -> <back end>
422 In practice, `ShCompile()` takes shader strings, default version, and
423 warning/error and other options for controlling compilation.
425 ## Basic Internal Operation
427 * Initial lexical analysis is done by the preprocessor in
428 `MachineIndependent/Preprocessor`, and then refined by a GLSL scanner
429 in `MachineIndependent/Scan.cpp`. There is currently no use of flex.
431 * Code is parsed using bison on `MachineIndependent/glslang.y` with the
432 aid of a symbol table and an AST. The symbol table is not passed on to
433 the back-end; the intermediate representation stands on its own.
434 The tree is built by the grammar productions, many of which are
435 offloaded into `ParseHelper.cpp`, and by `Intermediate.cpp`.
437 * The intermediate representation is very high-level, and represented
438 as an in-memory tree. This serves to lose no information from the
439 original program, and to have efficient transfer of the result from
440 parsing to the back-end. In the AST, constants are propagated and
441 folded, and a very small amount of dead code is eliminated.
443 To aid linking and reflection, the last top-level branch in the AST
444 lists all global symbols.
446 * The primary algorithm of the back-end compiler is to traverse the
447 tree (high-level intermediate representation), and create an internal
448 object code representation. There is an example of how to do this
449 in `MachineIndependent/intermOut.cpp`.
451 * Reduction of the tree to a linear byte-code style low-level intermediate
452 representation is likely a good way to generate fully optimized code.
454 * There is currently some dead old-style linker-type code still lying around.
456 * Memory pool: parsing uses types derived from C++ `std` types, using a
457 custom allocator that puts them in a memory pool. This makes allocation
458 of individual container/contents just few cycles and deallocation free.
459 This pool is popped after the AST is made and processed.
461 The use is simple: if you are going to call `new`, there are three cases:
463 - the object comes from the pool (its base class has the macro
464 `POOL_ALLOCATOR_NEW_DELETE` in it) and you do not have to call `delete`
466 - it is a `TString`, in which case call `NewPoolTString()`, which gets
467 it from the pool, and there is no corresponding `delete`
469 - the object does not come from the pool, and you have to do normal
470 C++ memory management of what you `new`
472 * Features can be protected by version/extension/stage/profile:
473 See the comment in `glslang/MachineIndependent/Versions.cpp`.
475 [cmake]: https://cmake.org/
476 [python]: https://www.python.org/
477 [bison]: https://www.gnu.org/software/bison/
478 [googletest]: https://github.com/google/googletest
479 [bison-gnu-win32]: http://gnuwin32.sourceforge.net/packages/bison.htm
480 [master-tot-release]: https://github.com/KhronosGroup/glslang/releases/tag/master-tot