GLSL compiler, take 2

Anon: i915-class?!

Fri, 11 Jun 2010 06:49:23 -0700

As in like the i945 in my laptop?! That would be interesting (in a good way)... This might speed up Flash http://blogs.adobe.com/penguin.swf/2008/05/flash_uses_the_gpu.html . Would it also provide enough support so super new OpenGL tutorials like http://duriansoftware.com/joe/An-intro-to-modern-OpenGL.-Table-of-Contents.html would be supported on i915-class hardware?

Anonymous: Benefits

Fri, 11 Jun 2010 15:33:27 -0700

What are the benefits of the compiler rewrite? Will it make the codebase more compact/streamlined? Will it enable support of higher GLSL versions? Will it improve performance (if so, how much have you measured?)?

IanRomanick: RE: i915-class?!

Sat, 12 Jun 2010 22:38:22 -0700

i915 can't do full GLSL, but it can handle the subset (mostly changes regarding loops and if-statement) in OpenGL ES 2.0. We want to enable that.

IanRomanick: RE: Benefits

Sat, 12 Jun 2010 22:48:18 -0700

The current compiler is not very good. It was written by Michal Krol as his final project at university. Given that, it's pretty amazing how well it works. However, the list of things that need to be fixed is long and runs from the frontend through the backend. Michal and I had a long discussion about it at XDS 2008. He really wanted to rewrite it, but he was (and presumably still is) too busy with other work.

I don't want to make any performance statements since we don't even have the compiler in Mesa. However, the current architecture should make it quite a bit easier to write new optimization passes. This is quite difficult in the current Mesa compiler. We're basing the architecture largely on "Advanced Compiler Design and Implementation" by Steven Muchnick.