103 lines
3.8 KiB
Markdown
103 lines
3.8 KiB
Markdown
GLSL optimizer
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==============
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A C++ library that takes GLSL shaders, does some GPU-independent optimizations on them
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and outputs GLSL or Metal source back. Optimizations are function inlining, dead code removal, copy propagation,
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constant folding, constant propagation, arithmetic optimizations and so on.
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Apparently quite a few mobile platforms are pretty bad at optimizing shaders; and
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unfortunately they *also* lack offline shader compilers. So using a GLSL optimizer offline
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before can make the shader run much faster on a platform like that. See performance numbers
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in [this blog post](http://aras-p.info/blog/2010/09/29/glsl-optimizer/).
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Even for drivers that have decent shader optimization, GLSL optimizer could be useful to just strip away
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dead code, make shaders smaller and do uniform/input reflection offline.
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Almost all actual code is [Mesa 3D's GLSL](http://cgit.freedesktop.org/mesa/mesa/log/)
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compiler; all this library does is spits out optimized GLSL or Metal back, and adds GLES type precision
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handling to the optimizer.
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This GLSL optimizer is made for [Unity's](http://unity3d.com/) purposes and is built-in
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starting with Unity 3.0.
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GLSL Optimizer is licensed according to the terms of the MIT license.
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See [change log here](Changelog.md).
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Usage
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-----
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Visual Studio 2010 (Windows, x86/x64) and Xcode 5+ (Mac, i386) project files for a static
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library are provided in `projects/vs2010/glsl_optimizer.sln` and `projects/xcode5/glsl_optimizer_lib`
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respectively.
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> Note: only the VS and Xcode project files are maintained and should work at any time.
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> There's also a cmake and gyp build system for Linux et al., and some stuff in contrib folder -
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> all that may or might not work.
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For Linux you can use cmake. Just type "cmake . && make" in the root directory.
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This will build the optimizer library and some executable binaries.
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Interface for the library is `src/glsl/glsl_optimizer.h`. General usage is:
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ctx = glslopt_initialize(targetVersion);
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for (lots of shaders) {
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shader = glslopt_optimize (ctx, shaderType, shaderSource, options);
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if (glslopt_get_status (shader)) {
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newSource = glslopt_get_output (shader);
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} else {
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errorLog = glslopt_get_log (shader);
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}
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glslopt_shader_delete (shader);
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}
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glslopt_cleanup (ctx);
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Tests
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-----
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There's a testing suite for catching regressions, see `tests` folder. In VS, build
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and run `glsl_optimizer_tests` project; in Xcode use `projects/xcode5/glsl_optimizer_tests`
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project. The test executable requires path to the `tests` folder as an argument.
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Each test comes as three text files; input, expected IR dump and expected optimized
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GLSL dump. GLES3 tests are also converted into Metal.
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If you're making changes to the project and want pull requests accepted easier, I'd
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appreciate if there would be no test suite regressions. If you are implementing a
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feature, it would be cool to add tests to cover it as well!
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Notes
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-----
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* GLSL versions 1.10 and 1.20 are supported. 1.10 is the default, use #version 120 to specify
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1.20. Higher GLSL versions might work, but aren't tested now.
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* GLSL ES versions 1.00 and 3.00 are supported.
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Status and Future
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-----------------
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**Note**: As of mid-2016, the project is unlikely to have any significant developments. At Unity we are largely moving to a different
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shader compilation pipeline, with glsl-optimizer mostly not used. So from my side there won't be significant work done on it :(
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Dev Notes
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---------
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Pulling Mesa upstream:
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git fetch upstream
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git merge upstream/master
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sh removeDeletedByUs.sh
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# inspect files, git rm unneeded ones, fix conflicts etc.
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# git commit
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Rebuilding flex/bison parsers:
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* When .y/.l files are changed, the parsers are *not* rebuilt automatically,
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* Run ./generateParsers.sh to do that. You'll need bison & flex (on Mac, do "Install Command Line Tools" from Xcode)
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* I use bison 2.3 and flex 2.5.35 (in OS X 10.8/10.9)
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