If the branch is short, that is what happens (for very divergent warps, the threshold is 7 ops, otherwise its 4). Even thought it will not ignore the other. It just fills the other warp with NOP.
Might be that with pure shaders it does actually branch (don't know, avoid it as I don't want to see regular cards die down. GPUs are better at brute force streaming than jumping) but for the purpose of CUDA it would be catastrophal.
As well you don't really need it within CUDA that much as in Shaders for example. You do pure math calculations and you first would have me to show the mathematical algorithm that has an IF in ... there are cases, but those are more or less all covered by the prediction (which is an evolved version of previous shader generations prediction).
mark: what did you want to acomplish with CUDA?
Might be that with pure shaders it does actually branch (don't know, avoid it as I don't want to see regular cards die down. GPUs are better at brute force streaming than jumping) but for the purpose of CUDA it would be catastrophal.
As well you don't really need it within CUDA that much as in Shaders for example. You do pure math calculations and you first would have me to show the mathematical algorithm that has an IF in ... there are cases, but those are more or less all covered by the prediction (which is an evolved version of previous shader generations prediction).
mark: what did you want to acomplish with CUDA?