Originally posted by StealthHawk
Please read this post by CatalystMaker here
Something very important that he says.
Notice that he is quoting Tim Sweeney. Notice that Sweeney says that any function that has the same result as the original for any argument is a valid optimization. Then notice that CatalystMaker says that is exactly what they did.
Now look at your example. It does not have the same output for every argument. If c = false then you are skipping instructions.
wow you are correct, the program model of mine is what i think ati is doing, the shaders only work on GT4 sky and water