Standard, Portable Intermediate Representation - V (SPIR-V) is an intermediate language designed and standardized by the Khronos Group for shaders. It is intended to be a compiler target for a number of different languages. In the Vulkan API, shaders are required to be compiled to SPIR-V before they can be loaded. SPIR-V is intended to provide developers with the freedom to develop their shaders in any language they want (as long as it can be compiled to SPIR-V), and avoid the need for an OpenGL (or Vulkan) implementation to provide compilers for multiple languages. 

Support for SPIR-V shader binaries was added to OpenGL core with version 4.6, but is also available via the ARB_gl_spirv extension for earlier OpenGL versions.

Currently, the Khronos Group provides a reference compiler for compiling GLSL to SPIR-V. It is available on GitHub at https://github.com/KhronosGroup/glslang.

In this recipe, we'll go through the steps involved in precompiling a GLSL shader pair to SPIR-V, and then load it into an OpenGL program.