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
24 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).
26 **Status**: Virtually complete, with results carrying similar weight as the specifications.
28 ### HLSL -> AST Front End
30 An HLSL front-end for translation of an approximation of HLSL to glslang's AST form.
32 **Status**: Partially complete. Semantics are not reference quality and input is not validated.
33 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.
35 See [issue 362](https://github.com/KhronosGroup/glslang/issues/362) and [issue 701](https://github.com/KhronosGroup/glslang/issues/701) for current status.
37 ### AST -> SPIR-V Back End
39 Translates glslang's AST to the Khronos-specified SPIR-V intermediate language.
41 **Status**: Virtually complete.
45 An API for getting reflection information from the AST, reflection types/variables/etc. from the HLL source (not the SPIR-V).
47 **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.
49 ### Standalone Wrapper
51 `glslangValidator` is command-line tool for accessing the functionality above.
55 Tasks waiting to be done are documented as GitHub issues.
59 Also see the Khronos landing page for glslang as a reference front end:
61 https://www.khronos.org/opengles/sdk/tools/Reference-Compiler/
63 The above page, while not kept up to date, includes additional information regarding glslang as a reference validator.
67 ## Execution of Standalone Wrapper
69 To use the standalone binary form, execute `glslangValidator`, and it will print
70 a usage statement. Basic operation is to give it a file containing a shader,
71 and it will print out warnings/errors and optionally an AST.
73 The applied stage-specific rules are based on the file extension:
74 * `.vert` for a vertex shader
75 * `.tesc` for a tessellation control shader
76 * `.tese` for a tessellation evaluation shader
77 * `.geom` for a geometry shader
78 * `.frag` for a fragment shader
79 * `.comp` for a compute shader
81 There is also a non-shader extension
82 * `.conf` for a configuration file of limits, see usage statement for example
86 Instead of building manually, you can also download the binaries for your
87 platform directly from the [master-tot release][master-tot-release] on GitHub.
88 Those binaries are automatically uploaded by the buildbots after successful
89 testing and they always reflect the current top of the tree of the master
95 (For MSVS: 2015 is recommended, 2013 is fully supported/tested, and 2010 support is attempted, but not tested.)
96 * [CMake][cmake]: for generating compilation targets.
97 * make: _Linux_, ninja is an alternative, if configured.
98 * [Python 3.x][python]: for executing SPIRV-Tools scripts. (Optional if not using SPIRV-Tools and the 'External' subdirectory does not exist.)
99 * [bison][bison]: _optional_, but needed when changing the grammar (glslang.y).
100 * [googletest][googletest]: _optional_, but should use if making any changes to glslang.
104 The following steps assume a Bash shell. On Windows, that could be the Git Bash
105 shell or some other shell of your choosing.
107 #### 1) Check-Out this project
110 cd <parent of where you want glslang to be>
111 git clone https://github.com/KhronosGroup/glslang.git
114 #### 2) Check-Out External Projects
117 cd <the directory glslang was cloned to, "External" will be a subdirectory>
118 git clone https://github.com/google/googletest.git External/googletest
121 If you want to use googletest with Visual Studio 2013, you also need to check out an older version:
124 # to use googletest with Visual Studio 2013
125 cd External/googletest
126 git checkout 440527a61e1c91188195f7de212c63c77e8f0a45
130 If you wish to assure that SPIR-V generated from HLSL is legal for Vulkan,
131 wish to invoke -Os to reduce SPIR-V size from HLSL or GLSL, or wish to run the
132 integrated test suite, install spirv-tools with this:
135 ./update_glslang_sources.py
140 Assume the source directory is `$SOURCE_DIR` and the build directory is
141 `$BUILD_DIR`. First ensure the build directory exists, then navigate to it:
148 For building on Linux:
151 cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="$(pwd)/install" $SOURCE_DIR
152 # "Release" (for CMAKE_BUILD_TYPE) could also be "Debug" or "RelWithDebInfo"
155 For building on Android:
157 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
158 # If on Windows will be -DCMAKE_MAKE_PROGRAM=%ANDROID_NDK_ROOT%\prebuilt\windows-x86_64\bin\make.exe
159 # -G is needed for building on Windows
160 # -DANDROID_ABI can also be armeabi-v7a for 32 bit
163 For building on Windows:
166 cmake $SOURCE_DIR -DCMAKE_INSTALL_PREFIX="$(pwd)/install"
167 # The CMAKE_INSTALL_PREFIX part is for testing (explained later).
170 The CMake GUI also works for Windows (version 3.4.1 tested).
172 Also, consider using `git config --global core.fileMode false` (or with `--local`) on Windows
173 to prevent the addition of execution permission on files.
175 #### 4) Build and Install
182 cmake --build . --config Release --target install
183 # "Release" (for --config) could also be "Debug", "MinSizeRel", or "RelWithDebInfo"
186 If using MSVC, after running CMake to configure, use the
187 Configuration Manager to check the `INSTALL` project.
189 ### If you need to change the GLSL grammar
191 The grammar in `glslang/MachineIndependent/glslang.y` has to be recompiled with
192 bison if it changes, the output files are committed to the repo to avoid every
193 developer needing to have bison configured to compile the project when grammar
194 changes are quite infrequent. For windows you can get binaries from
195 [GnuWin32][bison-gnu-win32].
197 The command to rebuild is:
200 m4 -P MachineIndependent/glslang.m4 > MachineIndependent/glslang.y
201 bison --defines=MachineIndependent/glslang_tab.cpp.h
202 -t MachineIndependent/glslang.y
203 -o MachineIndependent/glslang_tab.cpp
206 The above commands are also available in the bash script in `updateGrammar`,
207 when executed from the glslang subdirectory of the glslang repository.
208 With no arguments it builds the full grammar, and with a "web" argument,
209 the web grammar subset (see more about the web subset in the next section).
211 ### Building to WASM for the Web and Node
213 Use the steps in [Build Steps](#build-steps), with the following notes/exceptions:
214 * For building the web subset of core glslang:
215 + execute `updateGrammar web` from the glslang subdirectory
216 (or if using your own scripts, `m4` needs a `-DGLSLANG_WEB` argument)
217 + set `-DENABLE_HLSL=OFF -DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF`
218 + turn on `-DENABLE_GLSLANG_JS=ON`
219 + optionally, for a minimum-size binary, turn on `-DENABLE_GLSLANG_WEBMIN=ON`
220 + optionally, for GLSL compilation error messages, turn on `-DENABLE_GLSLANG_WEB_DEVEL=ON`
221 * `emsdk` needs to be present in your executable search path, *PATH* for
222 Bash-like environments
223 + [Instructions located
224 here](https://emscripten.org/docs/getting_started/downloads.html#sdk-download-and-install)
225 * Wrap cmake call: `emcmake cmake`
226 * To get a fully minimized build, make sure to use `brotli` to compress the .js
232 emcmake cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_GLSLANG_WEB=ON \
233 -DENABLE_HLSL=OFF -DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF ..
236 ## Building glslang - Using vcpkg
238 You can download and install glslang using the [vcpkg](https://github.com/Microsoft/vcpkg) dependency manager:
240 git clone https://github.com/Microsoft/vcpkg.git
243 ./vcpkg integrate install
244 ./vcpkg install glslang
246 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.
250 Right now, there are two test harnesses existing in glslang: one is [Google
251 Test](gtests/), one is the [`runtests` script](Test/runtests). The former
252 runs unit tests and single-shader single-threaded integration tests, while
253 the latter runs multiple-shader linking tests and multi-threaded tests.
257 The [`runtests` script](Test/runtests) requires compiled binaries to be
258 installed into `$BUILD_DIR/install`. Please make sure you have supplied the
259 correct configuration to CMake (using `-DCMAKE_INSTALL_PREFIX`) when building;
260 otherwise, you may want to modify the path in the `runtests` script.
262 Running Google Test-backed tests:
271 ctest -C {Debug|Release|RelWithDebInfo|MinSizeRel}
273 # or, run the test binary directly
274 # (which gives more fine-grained control like filtering):
275 <dir-to-glslangtests-in-build-dir>/glslangtests
278 Running `runtests` script-backed tests:
281 cd $SOURCE_DIR/Test && ./runtests
284 If some tests fail with validation errors, there may be a mismatch between the
285 version of `spirv-val` on the system and the version of glslang. In this
286 case, it is necessary to run `update_glslang_sources.py`. See "Check-Out
287 External Projects" above for more details.
289 ### Contributing tests
291 Test results should always be included with a pull request that modifies
294 If you are writing unit tests, please use the Google Test framework and
295 place the tests under the `gtests/` directory.
297 Integration tests are placed in the `Test/` directory. It contains test input
298 and a subdirectory `baseResults/` that contains the expected results of the
299 tests. Both the tests and `baseResults/` are under source-code control.
301 Google Test runs those integration tests by reading the test input, compiling
302 them, and then compare against the expected results in `baseResults/`. The
303 integration tests to run via Google Test is registered in various
304 `gtests/*.FromFile.cpp` source files. `glslangtests` provides a command-line
305 option `--update-mode`, which, if supplied, will overwrite the golden files
306 under the `baseResults/` directory with real output from that invocation.
307 For more information, please check `gtests/` directory's
308 [README](gtests/README.md).
310 For the `runtests` script, it will generate current results in the
311 `localResults/` directory and `diff` them against the `baseResults/`.
312 When you want to update the tracked test results, they need to be
313 copied from `localResults/` to `baseResults/`. This can be done by
314 the `bump` shell script.
316 You can add your own private list of tests, not tracked publicly, by using
317 `localtestlist` to list non-tracked tests. This is automatically read
318 by `runtests` and included in the `diff` and `bump` process.
320 ## Programmatic Interfaces
322 Another piece of software can programmatically translate shaders to an AST
323 using one of two different interfaces:
324 * A new C++ class-oriented interface, or
325 * The original C functional interface
327 The `main()` in `StandAlone/StandAlone.cpp` shows examples using both styles.
329 ### C++ Class Interface (new, preferred)
331 This interface is in roughly the last 1/3 of `ShaderLang.h`. It is in the
332 glslang namespace and contains the following, here with suggested calls
333 for generating SPIR-V:
336 const char* GetEsslVersionString();
337 const char* GetGlslVersionString();
338 bool InitializeProcess();
339 void FinalizeProcess();
343 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientVulkan or EShClientOpenGL, 100);
344 setEnvClient(EShClientVulkan or EShClientOpenGL, EShTargetVulkan_1_0 or EShTargetVulkan_1_1 or EShTargetOpenGL_450);
345 setEnvTarget(EShTargetSpv, EShTargetSpv_1_0 or EShTargetSpv_1_3);
347 const char* getInfoLog();
352 const char* getInfoLog();
356 For just validating (not generating code), substitute these calls:
359 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientNone, 0);
360 setEnvClient(EShClientNone, 0);
361 setEnvTarget(EShTargetNone, 0);
364 See `ShaderLang.h` and the usage of it in `StandAlone/StandAlone.cpp` for more
365 details. There is a block comment giving more detail above the calls for
366 `setEnvInput, setEnvClient, and setEnvTarget`.
368 ### C Functional Interface (original)
370 This interface is in roughly the first 2/3 of `ShaderLang.h`, and referred to
371 as the `Sh*()` interface, as all the entry points start `Sh`.
373 The `Sh*()` interface takes a "compiler" call-back object, which it calls after
374 building call back that is passed the AST and can then execute a back end on it.
376 The following is a simplified resulting run-time call stack:
379 ShCompile(shader, compiler) -> compiler(AST) -> <back end>
382 In practice, `ShCompile()` takes shader strings, default version, and
383 warning/error and other options for controlling compilation.
385 ## Basic Internal Operation
387 * Initial lexical analysis is done by the preprocessor in
388 `MachineIndependent/Preprocessor`, and then refined by a GLSL scanner
389 in `MachineIndependent/Scan.cpp`. There is currently no use of flex.
391 * Code is parsed using bison on `MachineIndependent/glslang.y` with the
392 aid of a symbol table and an AST. The symbol table is not passed on to
393 the back-end; the intermediate representation stands on its own.
394 The tree is built by the grammar productions, many of which are
395 offloaded into `ParseHelper.cpp`, and by `Intermediate.cpp`.
397 * The intermediate representation is very high-level, and represented
398 as an in-memory tree. This serves to lose no information from the
399 original program, and to have efficient transfer of the result from
400 parsing to the back-end. In the AST, constants are propagated and
401 folded, and a very small amount of dead code is eliminated.
403 To aid linking and reflection, the last top-level branch in the AST
404 lists all global symbols.
406 * The primary algorithm of the back-end compiler is to traverse the
407 tree (high-level intermediate representation), and create an internal
408 object code representation. There is an example of how to do this
409 in `MachineIndependent/intermOut.cpp`.
411 * Reduction of the tree to a linear byte-code style low-level intermediate
412 representation is likely a good way to generate fully optimized code.
414 * There is currently some dead old-style linker-type code still lying around.
416 * Memory pool: parsing uses types derived from C++ `std` types, using a
417 custom allocator that puts them in a memory pool. This makes allocation
418 of individual container/contents just few cycles and deallocation free.
419 This pool is popped after the AST is made and processed.
421 The use is simple: if you are going to call `new`, there are three cases:
423 - the object comes from the pool (its base class has the macro
424 `POOL_ALLOCATOR_NEW_DELETE` in it) and you do not have to call `delete`
426 - it is a `TString`, in which case call `NewPoolTString()`, which gets
427 it from the pool, and there is no corresponding `delete`
429 - the object does not come from the pool, and you have to do normal
430 C++ memory management of what you `new`
432 * Features can be protected by version/extension/stage/profile:
433 See the comment in `glslang/MachineIndependent/Versions.cpp`.
435 [cmake]: https://cmake.org/
436 [python]: https://www.python.org/
437 [bison]: https://www.gnu.org/software/bison/
438 [googletest]: https://github.com/google/googletest
439 [bison-gnu-win32]: http://gnuwin32.sourceforge.net/packages/bison.htm
440 [master-tot-release]: https://github.com/KhronosGroup/glslang/releases/tag/master-tot