this post was submitted on 10 Jul 2023
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Programming

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How often does branchless programming actually matter? (self.programming)
submitted 1 year ago by firelizzard to c/programming
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I've started noticing articles and YouTube videos touting the benefits of branchless programming, making it sound like this is a hot new technique (or maybe a hot old technique) that everyone should be using. But it seems like it's only really applicable to data processing applications (as opposed to general programming) and there are very few times in my career where I've needed to use, much less optimize, data processing code. And when I do, I use someone else's library.

How often does branchless programming actually matter in the day to day life of an average developer?

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[–] graphicsguy 3 points 1 year ago

Also if you branch on a GPU, the compiler has to reserve enough registers to walk through both branches (handwavey), which means lower occupancy.

Often you have no choice, or removing the branch leaves you with just as much code so it's irrelevant. But sometimes it matters. If you know that a particular draw call will always use one side of the branch but not the other, a typical optimization is to compile a separate version of the shader that removes the unused branch and saves on registers