News

  1. Visual Studio 2013 is no longer supported

    As scheduled, Microsoft Visual Studio 2013 is no longer officially supported.
    Please upgrade to at least Visual Studio 2015.

  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.

  3. If you get a new compilation error due to a missing header, it might be caused by this planned removal:

SPIRV Folder, 1-May, 2020. Glslang, when installed through CMake, will install a SPIRV folder into ${CMAKE_INSTALL_INCLUDEDIR}. This SPIRV folder is being moved to glslang/SPIRV. During the transition the SPIRV folder will be installed into both locations. The old install of SPIRV/ will be removed as a CMake install target no sooner than May 1, 2020. See issue #1964.

If people are only using this location to get spirv.hpp, I recommend they get that from SPIRV-Headers instead.

appveyor status Continuous Deployment

Glslang Components and Status

There are several components:

Reference Validator and GLSL/ESSL -> AST Front End

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).

Status: Virtually complete, with results carrying similar weight as the specifications.

HLSL -> AST Front End

An HLSL front-end for translation of an approximation of HLSL to glslang's AST form.

Status: Partially complete. Semantics are not reference quality and input is not validated. This is in contrast to the DXC project, which receives a much larger investment and attempts to have definitive/reference-level semantics.

See issue 362 and issue 701 for current status.

AST -> SPIR-V Back End

Translates glslang's AST to the Khronos-specified SPIR-V intermediate language.

Status: Virtually complete.

Reflector

An API for getting reflection information from the AST, reflection types/variables/etc. from the HLL source (not the SPIR-V).

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.

Standalone Wrapper

glslangValidator is command-line tool for accessing the functionality above.

Status: Complete.

Tasks waiting to be done are documented as GitHub issues.

Other References

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, while not kept up to date, includes additional information regarding glslang as a reference validator.

How to Use Glslang

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:

For ray tracing pipeline shaders:

There is also a non-shader extension:

Building (CMake)

Instead of building manually, you can also download the binaries for your platform directly from the master-tot release on GitHub. Those binaries are automatically uploaded by the buildbots after successful testing and they always reflect the current top of the tree of the master branch.

Dependencies

Build steps

The following steps assume a Bash shell. On Windows, that could be the Git Bash shell or some other shell of your choosing.

1) Check-Out this project

cd <parent of where you want glslang to be>
git clone https://github.com/KhronosGroup/glslang.git

2) Check-Out External Projects

cd <the directory glslang was cloned to, "External" will be a subdirectory>
git clone https://github.com/google/googletest.git External/googletest

TEMPORARY NOTICE: additionally perform the following to avoid a current breakage in googletest:

cd External/googletest
git checkout 0c400f67fcf305869c5fb113dd296eca266c9725
cd ../..

If you wish to assure that SPIR-V generated from HLSL is legal for Vulkan, wish to invoke -Os to reduce SPIR-V size from HLSL or GLSL, or wish to run the integrated test suite, install spirv-tools with this:

./update_glslang_sources.py

3) Configure

Assume the source directory is $SOURCE_DIR and the build directory is $BUILD_DIR. First ensure the build directory exists, then navigate to it:

mkdir -p $BUILD_DIR
cd $BUILD_DIR

For building on Linux:

cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="$(pwd)/install" $SOURCE_DIR
# "Release" (for CMAKE_BUILD_TYPE) could also be "Debug" or "RelWithDebInfo"

For building on Android:

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
# If on Windows will be -DCMAKE_MAKE_PROGRAM=%ANDROID_NDK_HOME%\prebuilt\windows-x86_64\bin\make.exe
# -G is needed for building on Windows
# -DANDROID_ABI can also be armeabi-v7a for 32 bit

For building on Windows:

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).

Also, consider using git config --global core.fileMode false (or with --local) on Windows to prevent the addition of execution permission on files.

4) Build and Install

# for Linux:
make -j4 install

# for Windows:
cmake --build . --config Release --target install
# "Release" (for --config) could also be "Debug", "MinSizeRel", or "RelWithDebInfo"

If using MSVC, after running CMake to configure, use the Configuration Manager to check the INSTALL project.

Building (GN)

glslang can also be built with the GN build system.

1) Install depot_tools

Download depot_tools.zip, extract to a directory, and add this directory to your PATH.

2) Synchronize dependencies and generate build files

This only needs to be done once after updating glslang.

With the current directory set to your glslang checkout, type:

./update_glslang_sources.py
gclient sync --gclientfile=standalone.gclient
gn gen out/Default

3) Build

With the current directory set to your glslang checkout, type:

cd out/Default
ninja

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.

The command to rebuild is:

m4 -P MachineIndependent/glslang.m4 > MachineIndependent/glslang.y
bison --defines=MachineIndependent/glslang_tab.cpp.h
      -t MachineIndependent/glslang.y
      -o MachineIndependent/glslang_tab.cpp

The above commands are also available in the bash script in updateGrammar, when executed from the glslang subdirectory of the glslang repository. With no arguments it builds the full grammar, and with a "web" argument, the web grammar subset (see more about the web subset in the next section).

Building to WASM for the Web and Node

Building a standalone JS/WASM library for the Web and Node

Use the steps in Build Steps, with the following notes/exceptions:

Example:

emcmake cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_GLSLANG_JS=ON \
    -DENABLE_HLSL=OFF -DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF ..

Building glslang - Using vcpkg

You can download and install glslang using the vcpkg dependency manager:

git clone https://github.com/Microsoft/vcpkg.git
cd vcpkg
./bootstrap-vcpkg.sh
./vcpkg integrate install
./vcpkg install glslang

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 on the vcpkg repository.

Testing

Right now, there are two test harnesses existing in glslang: one is Google Test, one is the runtests script. 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 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:

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):
<dir-to-glslangtests-in-build-dir>/glslangtests

Running runtests script-backed tests:

cd $SOURCE_DIR/Test && ./runtests

If some tests fail with validation errors, there may be a mismatch between the version of spirv-val on the system and the version of glslang. In this case, it is necessary to run update_glslang_sources.py. See "Check-Out External Projects" above for more details.

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.

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:

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, here with suggested calls for generating SPIR-V:

const char* GetEsslVersionString();
const char* GetGlslVersionString();
bool InitializeProcess();
void FinalizeProcess();

class TShader
    setStrings(...);
    setEnvInput(EShSourceHlsl or EShSourceGlsl, stage,  EShClientVulkan or EShClientOpenGL, 100);
    setEnvClient(EShClientVulkan or EShClientOpenGL, EShTargetVulkan_1_0 or EShTargetVulkan_1_1 or EShTargetOpenGL_450);
    setEnvTarget(EShTargetSpv, EShTargetSpv_1_0 or EShTargetSpv_1_3);
    bool parse(...);
    const char* getInfoLog();

class TProgram
    void addShader(...);
    bool link(...);
    const char* getInfoLog();
    Reflection queries

For just validating (not generating code), substitute these calls:

    setEnvInput(EShSourceHlsl or EShSourceGlsl, stage,  EShClientNone, 0);
    setEnvClient(EShClientNone, 0);
    setEnvTarget(EShTargetNone, 0);

See ShaderLang.h and the usage of it in StandAlone/StandAlone.cpp for more details. There is a block comment giving more detail above the calls for setEnvInput, setEnvClient, and setEnvTarget.

C Functional Interface (original)

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 back end on it.

The following is a simplified resulting run-time call stack:

ShCompile(shader, compiler) -> compiler(AST) -> <back end>

In practice, ShCompile() takes shader strings, default version, and warning/error and other options for controlling compilation.

C Functional Interface (new)

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.

std::vector<uint32_t> compileShaderToSPIRV_Vulkan(glslang_stage_t stage, const char* shaderSource, const char* fileName)
{
    const glslang_input_t input = {
        .language = GLSLANG_SOURCE_GLSL,
        .stage = stage,
        .client = GLSLANG_CLIENT_VULKAN,
        .client_version = GLSLANG_TARGET_VULKAN_1_2,
        .target_language = GLSLANG_TARGET_SPV,
        .target_language_version = GLSLANG_TARGET_SPV_1_5,
        .code = shaderSource,
        .default_version = 100,
        .default_profile = GLSLANG_NO_PROFILE,
        .force_default_version_and_profile = false,
        .forward_compatible = false,
        .messages = GLSLANG_MSG_DEFAULT_BIT,
        .resource = reinterpret_cast<const glslang_resource_t*>(&glslang::DefaultTBuiltInResource),
    };

    glslang_shader_t* shader = glslang_shader_create(&input);

    if (!glslang_shader_preprocess(shader, &input)) {
        printf("GLSL preprocessing failed %s\n", fileName);
        printf("%s\n", glslang_shader_get_info_log(shader));
        printf("%s\n", glslang_shader_get_info_debug_log(shader));
        printf("%s\n", input.code);
        glslang_shader_delete(shader);
        return std::vector<uint32_t>();
    }

    if (!glslang_shader_parse(shader, &input)) {
        printf("GLSL parsing failed %s\n", fileName);
        printf("%s\n", glslang_shader_get_info_log(shader));
        printf("%s\n", glslang_shader_get_info_debug_log(shader));
        printf("%s\n", glslang_shader_get_preprocessed_code(shader));
        glslang_shader_delete(shader);
        return std::vector<uint32_t>();
    }

    glslang_program_t* program = glslang_program_create();
    glslang_program_add_shader(program, shader);

    if (!glslang_program_link(program, GLSLANG_MSG_SPV_RULES_BIT | GLSLANG_MSG_VULKAN_RULES_BIT)) {
        printf("GLSL linking failed %s\n", fileName);
        printf("%s\n", glslang_program_get_info_log(program));
        printf("%s\n", glslang_program_get_info_debug_log(program));
        glslang_program_delete(program);
        glslang_shader_delete(shader);
        return std::vector<uint32_t>();
    }

    glslang_program_SPIRV_generate(program, stage);

    std::vector<uint32_t> outShaderModule(glslang_program_SPIRV_get_size(program));
    glslang_program_SPIRV_get(program, outShaderModule.data());

    const char* spirv_messages = glslang_program_SPIRV_get_messages(program);
    if (spirv_messages)
        printf("(%s) %s\b", fileName, spirv_messages);

    glslang_program_delete(program);
    glslang_shader_delete(shader);

    return outShaderModule;
}

Basic Internal Operation