The glShaderBinary function provides us with the ability to load shaders that have been compiled to the SPIR-V format. This part is fairly straightforward.

The function that might be a bit more confusing is glSpecializeShader. We are required to call this function before the shader stage can be linked. This call is needed because a single SPIR-V file can have multiple entry points, and SPIR-V files can have specialization constants, which are parameters that the user can provide before it is compiled into native code. 

At a minimum, we need to define the entry point for our shader. Since the source language is GLSL, the entry point is main. We specify the entry point(s) via the second argument. For GLSL, we simply use the main constant string. The last three parameters can be used to define the specialization constants. The first of the three is the number of constants, the next is a pointer to an array of constant indices, and the last is a pointer to an array of constant values.

The process of specializing an SPIR-V shader is similar to compiling a GLSL shader. Before calling glSpecializeShader, or if specialization fails, the compile status will be GL_FALSE. If specialization succeeds, the compile status will be GL_TRUE. As with GLSL shaders, we can query the shader info log to get detailed error messages (see the Compiling a shader recipe).