GLSL optimizer

A C++ library that takes GLSL shaders, does some GPU-independent optimizations on them and outputs GLSL back. Optimizations are function inlining, dead code removal, copy propagation, constant folding, constant propagation, arithmetic optimizations and so on.

Apparently quite a few mobile platforms are pretty bad at optimizing GLSL shaders; and unfortunately they also lack offline shader compilers. So using a GLSL optimizer offline before can make the shader run much faster on a platform like that. See performance numbers in this blog post.

Almost all actual code is Mesa 3D's GLSL2 compiler; all this library does is spits out optimized GLSL back.

This GLSL optimizer is made for Unity's purposes and is built-in in Unity 3.0.

Usage

Visual Studio 2008 (Windows, x86) and Xcode 3.2 (Mac, i386) project files for a static library are provided in src/glsl/msvc/mesaglsl2.vcproj and src/glsl/xcode/mesaglsl2 respectively. A Linux Makefile (x86/x86_64) is at src/glsl.

Interface for the library is src/glsl/glsl_optimizer.h. General usage is:

ctx = glslopt_initialize();
for (lots of shaders) {
	shader = glslopt_optimize (ctx, shaderType, shaderSource, options);
	if (glslopt_get_status (shader)) {
		newSource = glslopt_get_output (shader);
	} else {
		errorLog = glslopt_get_log (shader);
	}
	glslopt_shader_delete (shader);
}
glslopt_cleanup (ctx);

Notes

• I haven't checked if/how it works with higher GLSL versions than the default (1.10?).