Also see the Khronos landing page for glslang as a reference front end: https://www.khronos.org/opengles/sdk/tools/Reference-Compiler/ The above page includes where to get binaries, and is kept up to date regarding the feature level of glslang. glslang ======= [![Build Status](https://travis-ci.org/KhronosGroup/glslang.svg?branch=master)](https://travis-ci.org/KhronosGroup/glslang) [![Build status](https://ci.appveyor.com/api/projects/status/q6fi9cb0qnhkla68/branch/master?svg=true)](https://ci.appveyor.com/project/Khronoswebmaster/glslang/branch/master) An OpenGL and OpenGL ES shader front end and validator. There are several components: 1. A GLSL/ESSL front-end for reference validation and translation of GLSL/ESSL into an AST. 2. An HLSL front-end for translation of a broad generic HLL into the AST. 3. A SPIR-V back end for translating the AST to SPIR-V. 4. A standalone wrapper, `glslangValidator`, that can be used as a command-line tool for the above. How to add a feature protected by a version/extension/stage/profile: See the comment in `glslang/MachineIndependent/Versions.cpp`. Tasks waiting to be done are documented as GitHub issues. Execution of Standalone Wrapper ------------------------------- To use the standalone binary form, execute `glslangValidator`, and it will print a usage statement. Basic operation is to give it a file containing a shader, and it will print out warnings/errors and optionally an AST. The applied stage-specific rules are based on the file extension: * `.vert` for a vertex shader * `.tesc` for a tessellation control shader * `.tese` for a tessellation evaluation shader * `.geom` for a geometry shader * `.frag` for a fragment shader * `.comp` for a compute shader There is also a non-shader extension * `.conf` for a configuration file of limits, see usage statement for example Building -------- ### Dependencies * [CMake][cmake]: for generating compilation targets. * [bison][bison]: _optional_, but needed when changing the grammar (glslang.y). * [googletest][googletest]: _optional_, but should use if making any changes to glslang. ### Build steps #### 1) Check-Out this project ```bash cd git clone git@github.com:KhronosGroup/glslang.git ``` #### 2) Check-Out External Projects ```bash cd git clone https://github.com/google/googletest.git External/googletest ``` #### 3) Configure Assume the source directory is `$SOURCE_DIR` and the build directory is `$BUILD_DIR`: For building on Linux (assuming using the Ninja generator): ```bash cd $BUILD_DIR cmake -GNinja -DCMAKE_BUILD_TYPE={Debug|Release|RelWithDebInfo} \ -DCMAKE_INSTALL_PREFIX=`pwd`/install $SOURCE_DIR ``` For building on Windows: ```bash cmake $SOURCE_DIR -DCMAKE_INSTALL_PREFIX=`pwd`/install # The CMAKE_INSTALL_PREFIX part is for testing (explained later). ``` The CMake GUI also works for Windows (version 3.4.1 tested). #### 4) Build and Install ```bash # for Linux: ninja install # for Windows: cmake --build . --config {Release|Debug|MinSizeRel|RelWithDebInfo} \ --target install ``` If using MSVC, after running CMake to configure, use the Configuration Manager to check the `INSTALL` project. ### If you need to change the GLSL grammar The grammar in `glslang/MachineIndependent/glslang.y` has to be recompiled with bison if it changes, the output files are committed to the repo to avoid every developer needing to have bison configured to compile the project when grammar changes are quite infrequent. For windows you can get binaries from [GnuWin32][bison-gnu-win32]. The command to rebuild is: ```bash bison --defines=MachineIndependent/glslang_tab.cpp.h -t MachineIndependent/glslang.y -o MachineIndependent/glslang_tab.cpp ``` The above command is also available in the bash script at `glslang/updateGrammar`. Testing ------- Right now, there are two test harnesses existing in glslang: one is [Google Test](gtests/), one is the [`runtests` script](Test/runtests). The former runs unit tests and single-shader single-threaded integration tests, while the latter runs multiple-shader linking tests and multi-threaded tests. ### Running tests The [`runtests` script](Test/runtests) requires compiled binaries to be installed into `$BUILD_DIR/install`. Please make sure you have supplied the correct configuration to CMake (using `-DCMAKE_INSTALL_PREFIX`) when building; otherwise, you may want to modify the path in the `runtests` script. Running Google Test-backed tests: ```bash cd $BUILD_DIR # for Linux: ctest # for Windows: ctest -C {Debug|Release|RelWithDebInfo|MinSizeRel} # or, run the test binary directly # (which gives more fine-grained control like filtering): /glslangtests ``` Running `runtests` script-backed tests: ```bash cd $SOURCE_DIR/Test && ./runtests ``` ### Contributing tests Test results should always be included with a pull request that modifies functionality. If you are writing unit tests, please use the Google Test framework and place the tests under the `gtests/` directory. Integration tests are placed in the `Test/` directory. It contains test input and a subdirectory `baseResults/` that contains the expected results of the tests. Both the tests and `baseResults/` are under source-code control. Google Test runs those integration tests by reading the test input, compiling them, and then compare against the expected results in `baseResults/`. The integration tests to run via Google Test is registered in various `gtests/*.FromFile.cpp` source files. `glslangtests` provides a command-line option `--update-mode`, which, if supplied, will overwrite the golden files under the `baseResults/` directory with real output from that invocation. For more information, please check `gtests/` directory's [README](gtests/README.md). For the `runtests` script, it will generate current results in the `localResults/` directory and `diff` them against the `baseResults/`. When you want to update the tracked test results, they need to be copied from `localResults/` to `baseResults/`. This can be done by the `bump` shell script. You can add your own private list of tests, not tracked publicly, by using `localtestlist` to list non-tracked tests. This is automatically read by `runtests` and included in the `diff` and `bump` process. Programmatic Interfaces ----------------------- Another piece of software can programmatically translate shaders to an AST using one of two different interfaces: * A new C++ class-oriented interface, or * The original C functional interface The `main()` in `StandAlone/StandAlone.cpp` shows examples using both styles. ### C++ Class Interface (new, preferred) This interface is in roughly the last 1/3 of `ShaderLang.h`. It is in the glslang namespace and contains the following. ```cxx const char* GetEsslVersionString(); const char* GetGlslVersionString(); bool InitializeProcess(); void FinalizeProcess(); class TShader bool parse(...); void setStrings(...); const char* getInfoLog(); class TProgram void addShader(...); bool link(...); const char* getInfoLog(); Reflection queries ``` See `ShaderLang.h` and the usage of it in `StandAlone/StandAlone.cpp` for more details. ### C Functional Interface (orignal) This interface is in roughly the first 2/3 of `ShaderLang.h`, and referred to as the `Sh*()` interface, as all the entry points start `Sh`. The `Sh*()` interface takes a "compiler" call-back object, which it calls after building call back that is passed the AST and can then execute a backend on it. The following is a simplified resulting run-time call stack: ```c ShCompile(shader, compiler) -> compiler(AST) -> ``` In practice, `ShCompile()` takes shader strings, default version, and warning/error and other options for controlling compilation. Basic Internal Operation ------------------------ * Initial lexical analysis is done by the preprocessor in `MachineIndependent/Preprocessor`, and then refined by a GLSL scanner in `MachineIndependent/Scan.cpp`. There is currently no use of flex. * Code is parsed using bison on `MachineIndependent/glslang.y` with the aid of a symbol table and an AST. The symbol table is not passed on to the back-end; the intermediate representation stands on its own. The tree is built by the grammar productions, many of which are offloaded into `ParseHelper.cpp`, and by `Intermediate.cpp`. * The intermediate representation is very high-level, and represented as an in-memory tree. This serves to lose no information from the original program, and to have efficient transfer of the result from parsing to the back-end. In the AST, constants are propogated and folded, and a very small amount of dead code is eliminated. To aid linking and reflection, the last top-level branch in the AST lists all global symbols. * The primary algorithm of the back-end compiler is to traverse the tree (high-level intermediate representation), and create an internal object code representation. There is an example of how to do this in `MachineIndependent/intermOut.cpp`. * Reduction of the tree to a linear byte-code style low-level intermediate representation is likely a good way to generate fully optimized code. * There is currently some dead old-style linker-type code still lying around. * Memory pool: parsing uses types derived from C++ `std` types, using a custom allocator that puts them in a memory pool. This makes allocation of individual container/contents just few cycles and deallocation free. This pool is popped after the AST is made and processed. The use is simple: if you are going to call `new`, there are three cases: - the object comes from the pool (its base class has the macro `POOL_ALLOCATOR_NEW_DELETE` in it) and you do not have to call `delete` - it is a `TString`, in which case call `NewPoolTString()`, which gets it from the pool, and there is no corresponding `delete` - the object does not come from the pool, and you have to do normal C++ memory management of what you `new` [cmake]: https://cmake.org/ [bison]: https://www.gnu.org/software/bison/ [googletest]: https://github.com/google/googletest [bison-gnu-win32]: http://gnuwin32.sourceforge.net/packages/bison.htm