glslang

glslang is an open-source reference compiler and validator for the OpenGL Shading Language (GLSL) that targets the SPIR-V intermediate representation. It is maintained as part of the Khronos Group’s toolkit for Vulkan and OpenGL, and it is widely used to translate GLSL shaders into SPIR-V for use in modern graphics pipelines.

The project provides multiple components: a GLSL/GLSL ES front end, a capability to incorporate an HLSL front end for cross-language translation, and a SPIR-V back end that emits valid SPIR-V modules. It also offers a C++ library that can be embedded into applications and a command-line utility named glslangValidator. This tool validates GLSL and GLSL ES source and can compile or translate it to SPIR-V, providing diagnostic messages for errors and warnings.

In practice, glslang serves as the reference compiler in the Vulkan ecosystem and is used by the Vulkan SDK, graphics engines, and shader tooling to ensure shader source conforms to language rules and to generate SPIR-V binaries. It supports a range of GLSL versions and extensions, and it includes mechanisms to handle HLSL-to-SPIR-V translation as part of cross-compilation workflows.

Licensing and development: glslang is released under the Apache License 2.0. Development is hosted publicly, with contributions from the community under Khronos Group governance. The project is designed to interoperate with related SPIR-V tooling, providing a standard path from high-level shader code to a portable intermediate representation used by Vulkan and other APIs.