# News

1. Visual Studio 2013 is no longer supported

As scheduled, Microsoft Visual Studio 2013 is no longer officially supported.

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:

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_ROOT/prebuilt/linux-x86_64/bin/make -DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK_ROOT/build/cmake/android.toolchain.cmake # If on Windows will be -DCMAKE_MAKE_PROGRAM=%ANDROID_NDK_ROOT%\prebuilt\windows-x86_64\bin\make.exe # -G is needed for building on Windows # -DANDROID_ABI can also be armeabi-v7a for 32 bit For building on Windows: cmake$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: • emsdk needs to be present in your executable search path, PATH for Bash-like environments: • Wrap cmake call: emcmake cmake • Set -DBUILD_TESTING=OFF -DENABLE_OPT=OFF -DINSTALL_GTEST=OFF. • Set -DENABLE_HLSL=OFF if HLSL is not needed. • For a standalone JS/WASM library, turn on -DENABLE_GLSLANG_JS=ON. • For building a minimum-size web subset of core glslang: • turn on -DENABLE_GLSLANG_WEBMIN=ON (disables HLSL) • execute updateGrammar web from the glslang subdirectory (or if using your own scripts, m4 needs a -DGLSLANG_WEB argument) • optionally, for GLSL compilation error messages, turn on -DENABLE_GLSLANG_WEBMIN_DEVEL=ON • To get a fully minimized build, make sure to use brotli to compress the .js and .wasm files 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.

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:

• 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, here with suggested calls for generating SPIR-V:

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

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
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.

## 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 propagated 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

• Features can be protected by version/extension/stage/profile: See the comment in glslang/MachineIndependent/Versions.cpp.

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