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Re: Checking shader optimizations

On Oct 29, 2007, at 12:33 PM, Stefan Dösinger wrote:

Hello,

I am looking for a way to check the code after it has been optimized by the
glsl implementation.
I have found something by chance: In the opengl shader builder, I can look at
some sort of ARB assembly in the GLSL log window.

What I am not sure about is if this is some sort of optimized code or not. I
don't mean hardware specific optimizations, but general things like constant
propagation, filtering out NOP operations like + 0.0 or * 1.0. Does anyone
have information about that?

I have heard that the code you see here is pre-optimization—an optimization pass is applied to the code but what you see does not reflect that pass. Also, I believe that there is also another optimization phase where the vertex and fragment shader are fused together into one big program, and that is also something that developers don't get to see.

AFAIK this is an undocumented, custom language. It's not too hard to read if you know ARB, but it's definitely got its own set of quirks. There's no public way to submit code to the OS in this language either. (If there is a private way, I don't know it.)

Really the anomaly is that they present this information to us at all, because there isn't much that we can do with it. The only thing I can think of is, if you suspect the GLSL parser is translating your program incorrectly, you might be able to use that view to demonstrate the issue. _______________________________________________
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 >Checking shader optimizations (From: Stefan Dösinger <email@hidden>)
 >Re: Checking shader optimizations (From: Stefan Dösinger <email@hidden>)



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