3 1. Default branch will be renamed from 'master' to 'main' [as requested by Khronos](https://github.com/KhronosGroup/glslang/issues/3107) on 01/30/2023.
5 2. Visual Studio 2013 is no longer supported
7 [As scheduled](https://github.com/KhronosGroup/glslang/blob/9eef54b2513ca6b40b47b07d24f453848b65c0df/README.md#planned-deprecationsremovals),
8 Microsoft Visual Studio 2013 is no longer officially supported. \
9 Please upgrade to at least Visual Studio 2015.
11 3. 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.
13 4. If you get a new **compilation error due to a missing header**, it might be caused by this planned removal:
15 **SPIRV Folder, 1-May, 2020.** Glslang, when installed through CMake,
16 will install a `SPIRV` folder into `${CMAKE_INSTALL_INCLUDEDIR}`.
17 This `SPIRV` folder is being moved to `glslang/SPIRV`.
18 During the transition the `SPIRV` folder will be installed into both locations.
19 The old install of `SPIRV/` will be removed as a CMake install target no sooner than May 1, 2020.
22 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.
24 [![appveyor status](https://ci.appveyor.com/api/projects/status/q6fi9cb0qnhkla68/branch/master?svg=true)](https://ci.appveyor.com/project/Khronoswebmaster/glslang/branch/master)
25 ![Continuous Deployment](https://github.com/KhronosGroup/glslang/actions/workflows/continuous_deployment.yml/badge.svg)
27 # Glslang Components and Status
29 There are several components:
31 ### Reference Validator and GLSL/ESSL -> AST Front End
33 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).
35 **Status**: Virtually complete, with results carrying similar weight as the specifications.
37 ### HLSL -> AST Front End
39 An HLSL front-end for translation of an approximation of HLSL to glslang's AST form.
41 **Status**: Partially complete. Semantics are not reference quality and input is not validated.
42 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.
44 See [issue 362](https://github.com/KhronosGroup/glslang/issues/362) and [issue 701](https://github.com/KhronosGroup/glslang/issues/701) for current status.
46 ### AST -> SPIR-V Back End
48 Translates glslang's AST to the Khronos-specified SPIR-V intermediate language.
50 **Status**: Virtually complete.
54 An API for getting reflection information from the AST, reflection types/variables/etc. from the HLL source (not the SPIR-V).
56 **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.
58 ### Standalone Wrapper
60 `glslangValidator` is command-line tool for accessing the functionality above.
64 Tasks waiting to be done are documented as GitHub issues.
68 Also see the Khronos landing page for glslang as a reference front end:
70 https://www.khronos.org/opengles/sdk/tools/Reference-Compiler/
72 The above page, while not kept up to date, includes additional information regarding glslang as a reference validator.
76 ## Execution of Standalone Wrapper
78 To use the standalone binary form, execute `glslangValidator`, and it will print
79 a usage statement. Basic operation is to give it a file containing a shader,
80 and it will print out warnings/errors and optionally an AST.
82 The applied stage-specific rules are based on the file extension:
83 * `.vert` for a vertex shader
84 * `.tesc` for a tessellation control shader
85 * `.tese` for a tessellation evaluation shader
86 * `.geom` for a geometry shader
87 * `.frag` for a fragment shader
88 * `.comp` for a compute shader
90 For ray tracing pipeline shaders:
91 * `.rgen` for a ray generation shader
92 * `.rint` for a ray intersection shader
93 * `.rahit` for a ray any-hit shader
94 * `.rchit` for a ray closest-hit shader
95 * `.rmiss` for a ray miss shader
96 * `.rcall` for a callable shader
98 There is also a non-shader extension:
99 * `.conf` for a configuration file of limits, see usage statement for example
103 Instead of building manually, you can also download the binaries for your
104 platform directly from the [master-tot release][master-tot-release] on GitHub.
105 Those binaries are automatically uploaded by the buildbots after successful
106 testing and they always reflect the current top of the tree of the master
112 (For MSVS: use 2015 or later.)
113 * [CMake][cmake]: for generating compilation targets.
114 * make: _Linux_, ninja is an alternative, if configured.
115 * [Python 3.x][python]: for executing SPIRV-Tools scripts. (Optional if not using SPIRV-Tools and the 'External' subdirectory does not exist.)
116 * [bison][bison]: _optional_, but needed when changing the grammar (glslang.y).
117 * [googletest][googletest]: _optional_, but should use if making any changes to glslang.
121 The following steps assume a Bash shell. On Windows, that could be the Git Bash
122 shell or some other shell of your choosing.
124 #### 1) Check-Out this project
127 cd <parent of where you want glslang to be>
128 git clone https://github.com/KhronosGroup/glslang.git
131 #### 2) Check-Out External Projects
134 cd <the directory glslang was cloned to, "External" will be a subdirectory>
135 git clone https://github.com/google/googletest.git External/googletest
138 TEMPORARY NOTICE: additionally perform the following to avoid a current
139 breakage in googletest:
142 cd External/googletest
143 git checkout 0c400f67fcf305869c5fb113dd296eca266c9725
147 If you wish to assure that SPIR-V generated from HLSL is legal for Vulkan,
148 wish to invoke -Os to reduce SPIR-V size from HLSL or GLSL, or wish to run the
149 integrated test suite, install spirv-tools with this:
152 ./update_glslang_sources.py
157 Assume the source directory is `$SOURCE_DIR` and the build directory is
158 `$BUILD_DIR`. First ensure the build directory exists, then navigate to it:
165 For building on Linux:
168 cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="$(pwd)/install" $SOURCE_DIR
169 # "Release" (for CMAKE_BUILD_TYPE) could also be "Debug" or "RelWithDebInfo"
172 For building on Android:
174 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=$ANDROID_NDK_HOME/prebuilt/linux-x86_64/bin/make -DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK_HOME/build/cmake/android.toolchain.cmake
175 # If on Windows will be -DCMAKE_MAKE_PROGRAM=%ANDROID_NDK_HOME%\prebuilt\windows-x86_64\bin\make.exe
176 # -G is needed for building on Windows
177 # -DANDROID_ABI can also be armeabi-v7a for 32 bit
180 For building on Windows:
183 cmake $SOURCE_DIR -DCMAKE_INSTALL_PREFIX="$(pwd)/install"
184 # The CMAKE_INSTALL_PREFIX part is for testing (explained later).
187 The CMake GUI also works for Windows (version 3.4.1 tested).
189 Also, consider using `git config --global core.fileMode false` (or with `--local`) on Windows
190 to prevent the addition of execution permission on files.
192 #### 4) Build and Install
199 cmake --build . --config Release --target install
200 # "Release" (for --config) could also be "Debug", "MinSizeRel", or "RelWithDebInfo"
203 If using MSVC, after running CMake to configure, use the
204 Configuration Manager to check the `INSTALL` project.
208 glslang can also be built with the [GN build system](https://gn.googlesource.com/gn/).
210 #### 1) Install `depot_tools`
212 Download [depot_tools.zip](https://storage.googleapis.com/chrome-infra/depot_tools.zip),
213 extract to a directory, and add this directory to your `PATH`.
215 #### 2) Synchronize dependencies and generate build files
217 This only needs to be done once after updating `glslang`.
219 With the current directory set to your `glslang` checkout, type:
222 ./update_glslang_sources.py
223 gclient sync --gclientfile=standalone.gclient
229 With the current directory set to your `glslang` checkout, type:
236 ### If you need to change the GLSL grammar
238 The grammar in `glslang/MachineIndependent/glslang.y` has to be recompiled with
239 bison if it changes, the output files are committed to the repo to avoid every
240 developer needing to have bison configured to compile the project when grammar
241 changes are quite infrequent. For windows you can get binaries from
242 [GnuWin32][bison-gnu-win32].
244 The command to rebuild is:
247 m4 -P MachineIndependent/glslang.m4 > MachineIndependent/glslang.y
248 bison --defines=MachineIndependent/glslang_tab.cpp.h
249 -t MachineIndependent/glslang.y
250 -o MachineIndependent/glslang_tab.cpp
253 The above commands are also available in the bash script in `updateGrammar`,
254 when executed from the glslang subdirectory of the glslang repository.
255 With no arguments it builds the full grammar, and with a "web" argument,
256 the web grammar subset (see more about the web subset in the next section).
258 ### Building to WASM for the Web and Node
259 ### Building a standalone JS/WASM library for the Web and Node
261 Use the steps in [Build Steps](#build-steps), with the following notes/exceptions:
262 * `emsdk` needs to be present in your executable search path, *PATH* for
263 Bash-like environments:
264 + [Instructions located here](https://emscripten.org/docs/getting_started/downloads.html#sdk-download-and-install)
265 * Wrap cmake call: `emcmake cmake`
266 * Set `-DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF`.
267 * Set `-DENABLE_HLSL=OFF` if HLSL is not needed.
268 * For a standalone JS/WASM library, turn on `-DENABLE_GLSLANG_JS=ON`.
269 * For building a minimum-size web subset of core glslang:
270 + turn on `-DENABLE_GLSLANG_WEBMIN=ON` (disables HLSL)
271 + execute `updateGrammar web` from the glslang subdirectory
272 (or if using your own scripts, `m4` needs a `-DGLSLANG_WEB` argument)
273 + optionally, for GLSL compilation error messages, turn on
274 `-DENABLE_GLSLANG_WEBMIN_DEVEL=ON`
275 * To get a fully minimized build, make sure to use `brotli` to compress the .js
281 emcmake cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_GLSLANG_JS=ON \
282 -DENABLE_HLSL=OFF -DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF ..
285 ## Building glslang - Using vcpkg
287 You can download and install glslang using the [vcpkg](https://github.com/Microsoft/vcpkg) dependency manager:
289 git clone https://github.com/Microsoft/vcpkg.git
292 ./vcpkg integrate install
293 ./vcpkg install glslang
295 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.
299 Right now, there are two test harnesses existing in glslang: one is [Google
300 Test](gtests/), one is the [`runtests` script](Test/runtests). The former
301 runs unit tests and single-shader single-threaded integration tests, while
302 the latter runs multiple-shader linking tests and multi-threaded tests.
306 The [`runtests` script](Test/runtests) requires compiled binaries to be
307 installed into `$BUILD_DIR/install`. Please make sure you have supplied the
308 correct configuration to CMake (using `-DCMAKE_INSTALL_PREFIX`) when building;
309 otherwise, you may want to modify the path in the `runtests` script.
311 Running Google Test-backed tests:
320 ctest -C {Debug|Release|RelWithDebInfo|MinSizeRel}
322 # or, run the test binary directly
323 # (which gives more fine-grained control like filtering):
324 <dir-to-glslangtests-in-build-dir>/glslangtests
327 Running `runtests` script-backed tests:
330 cd $SOURCE_DIR/Test && ./runtests
333 If some tests fail with validation errors, there may be a mismatch between the
334 version of `spirv-val` on the system and the version of glslang. In this
335 case, it is necessary to run `update_glslang_sources.py`. See "Check-Out
336 External Projects" above for more details.
338 ### Contributing tests
340 Test results should always be included with a pull request that modifies
343 If you are writing unit tests, please use the Google Test framework and
344 place the tests under the `gtests/` directory.
346 Integration tests are placed in the `Test/` directory. It contains test input
347 and a subdirectory `baseResults/` that contains the expected results of the
348 tests. Both the tests and `baseResults/` are under source-code control.
350 Google Test runs those integration tests by reading the test input, compiling
351 them, and then compare against the expected results in `baseResults/`. The
352 integration tests to run via Google Test is registered in various
353 `gtests/*.FromFile.cpp` source files. `glslangtests` provides a command-line
354 option `--update-mode`, which, if supplied, will overwrite the golden files
355 under the `baseResults/` directory with real output from that invocation.
356 For more information, please check `gtests/` directory's
357 [README](gtests/README.md).
359 For the `runtests` script, it will generate current results in the
360 `localResults/` directory and `diff` them against the `baseResults/`.
361 When you want to update the tracked test results, they need to be
362 copied from `localResults/` to `baseResults/`. This can be done by
363 the `bump` shell script.
365 You can add your own private list of tests, not tracked publicly, by using
366 `localtestlist` to list non-tracked tests. This is automatically read
367 by `runtests` and included in the `diff` and `bump` process.
369 ## Programmatic Interfaces
371 Another piece of software can programmatically translate shaders to an AST
372 using one of two different interfaces:
373 * A new C++ class-oriented interface, or
374 * The original C functional interface
376 The `main()` in `StandAlone/StandAlone.cpp` shows examples using both styles.
378 ### C++ Class Interface (new, preferred)
380 This interface is in roughly the last 1/3 of `ShaderLang.h`. It is in the
381 glslang namespace and contains the following, here with suggested calls
382 for generating SPIR-V:
385 const char* GetEsslVersionString();
386 const char* GetGlslVersionString();
387 bool InitializeProcess();
388 void FinalizeProcess();
392 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientVulkan or EShClientOpenGL, 100);
393 setEnvClient(EShClientVulkan or EShClientOpenGL, EShTargetVulkan_1_0 or EShTargetVulkan_1_1 or EShTargetOpenGL_450);
394 setEnvTarget(EShTargetSpv, EShTargetSpv_1_0 or EShTargetSpv_1_3);
396 const char* getInfoLog();
401 const char* getInfoLog();
405 For just validating (not generating code), substitute these calls:
408 setEnvInput(EShSourceHlsl or EShSourceGlsl, stage, EShClientNone, 0);
409 setEnvClient(EShClientNone, 0);
410 setEnvTarget(EShTargetNone, 0);
413 See `ShaderLang.h` and the usage of it in `StandAlone/StandAlone.cpp` for more
414 details. There is a block comment giving more detail above the calls for
415 `setEnvInput, setEnvClient, and setEnvTarget`.
417 ### C Functional Interface (original)
419 This interface is in roughly the first 2/3 of `ShaderLang.h`, and referred to
420 as the `Sh*()` interface, as all the entry points start `Sh`.
422 The `Sh*()` interface takes a "compiler" call-back object, which it calls after
423 building call back that is passed the AST and can then execute a back end on it.
425 The following is a simplified resulting run-time call stack:
428 ShCompile(shader, compiler) -> compiler(AST) -> <back end>
431 In practice, `ShCompile()` takes shader strings, default version, and
432 warning/error and other options for controlling compilation.
434 ### C Functional Interface (new)
436 This interface is located `glslang_c_interface.h` and exposes functionality similar to the C++ interface. The following snippet is a complete example showing how to compile GLSL into SPIR-V 1.5 for Vulkan 1.2.
439 std::vector<uint32_t> compileShaderToSPIRV_Vulkan(glslang_stage_t stage, const char* shaderSource, const char* fileName)
441 const glslang_input_t input = {
442 .language = GLSLANG_SOURCE_GLSL,
444 .client = GLSLANG_CLIENT_VULKAN,
445 .client_version = GLSLANG_TARGET_VULKAN_1_2,
446 .target_language = GLSLANG_TARGET_SPV,
447 .target_language_version = GLSLANG_TARGET_SPV_1_5,
448 .code = shaderSource,
449 .default_version = 100,
450 .default_profile = GLSLANG_NO_PROFILE,
451 .force_default_version_and_profile = false,
452 .forward_compatible = false,
453 .messages = GLSLANG_MSG_DEFAULT_BIT,
454 .resource = reinterpret_cast<const glslang_resource_t*>(&glslang::DefaultTBuiltInResource),
457 glslang_shader_t* shader = glslang_shader_create(&input);
459 if (!glslang_shader_preprocess(shader, &input)) {
460 printf("GLSL preprocessing failed %s\n", fileName);
461 printf("%s\n", glslang_shader_get_info_log(shader));
462 printf("%s\n", glslang_shader_get_info_debug_log(shader));
463 printf("%s\n", input.code);
464 glslang_shader_delete(shader);
465 return std::vector<uint32_t>();
468 if (!glslang_shader_parse(shader, &input)) {
469 printf("GLSL parsing failed %s\n", fileName);
470 printf("%s\n", glslang_shader_get_info_log(shader));
471 printf("%s\n", glslang_shader_get_info_debug_log(shader));
472 printf("%s\n", glslang_shader_get_preprocessed_code(shader));
473 glslang_shader_delete(shader);
474 return std::vector<uint32_t>();
477 glslang_program_t* program = glslang_program_create();
478 glslang_program_add_shader(program, shader);
480 if (!glslang_program_link(program, GLSLANG_MSG_SPV_RULES_BIT | GLSLANG_MSG_VULKAN_RULES_BIT)) {
481 printf("GLSL linking failed %s\n", fileName);
482 printf("%s\n", glslang_program_get_info_log(program));
483 printf("%s\n", glslang_program_get_info_debug_log(program));
484 glslang_program_delete(program);
485 glslang_shader_delete(shader);
486 return std::vector<uint32_t>();
489 glslang_program_SPIRV_generate(program, stage);
491 std::vector<uint32_t> outShaderModule(glslang_program_SPIRV_get_size(program));
492 glslang_program_SPIRV_get(program, outShaderModule.data());
494 const char* spirv_messages = glslang_program_SPIRV_get_messages(program);
496 printf("(%s) %s\b", fileName, spirv_messages);
498 glslang_program_delete(program);
499 glslang_shader_delete(shader);
501 return outShaderModule;
505 ## Basic Internal Operation
507 * Initial lexical analysis is done by the preprocessor in
508 `MachineIndependent/Preprocessor`, and then refined by a GLSL scanner
509 in `MachineIndependent/Scan.cpp`. There is currently no use of flex.
511 * Code is parsed using bison on `MachineIndependent/glslang.y` with the
512 aid of a symbol table and an AST. The symbol table is not passed on to
513 the back-end; the intermediate representation stands on its own.
514 The tree is built by the grammar productions, many of which are
515 offloaded into `ParseHelper.cpp`, and by `Intermediate.cpp`.
517 * The intermediate representation is very high-level, and represented
518 as an in-memory tree. This serves to lose no information from the
519 original program, and to have efficient transfer of the result from
520 parsing to the back-end. In the AST, constants are propagated and
521 folded, and a very small amount of dead code is eliminated.
523 To aid linking and reflection, the last top-level branch in the AST
524 lists all global symbols.
526 * The primary algorithm of the back-end compiler is to traverse the
527 tree (high-level intermediate representation), and create an internal
528 object code representation. There is an example of how to do this
529 in `MachineIndependent/intermOut.cpp`.
531 * Reduction of the tree to a linear byte-code style low-level intermediate
532 representation is likely a good way to generate fully optimized code.
534 * There is currently some dead old-style linker-type code still lying around.
536 * Memory pool: parsing uses types derived from C++ `std` types, using a
537 custom allocator that puts them in a memory pool. This makes allocation
538 of individual container/contents just few cycles and deallocation free.
539 This pool is popped after the AST is made and processed.
541 The use is simple: if you are going to call `new`, there are three cases:
543 - the object comes from the pool (its base class has the macro
544 `POOL_ALLOCATOR_NEW_DELETE` in it) and you do not have to call `delete`
546 - it is a `TString`, in which case call `NewPoolTString()`, which gets
547 it from the pool, and there is no corresponding `delete`
549 - the object does not come from the pool, and you have to do normal
550 C++ memory management of what you `new`
552 * Features can be protected by version/extension/stage/profile:
553 See the comment in `glslang/MachineIndependent/Versions.cpp`.
555 [cmake]: https://cmake.org/
556 [python]: https://www.python.org/
557 [bison]: https://www.gnu.org/software/bison/
558 [googletest]: https://github.com/google/googletest
559 [bison-gnu-win32]: http://gnuwin32.sourceforge.net/packages/bison.htm
560 [master-tot-release]: https://github.com/KhronosGroup/glslang/releases/tag/master-tot