How often does branchless programming actually matter? (programming.dev)

submitted 1 year ago by firelizzard@programming.dev to c/programming@programming.dev

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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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[-] ZILtoid1991@kbin.social 8 points 1 year ago

It's useful in digital signal processing, but otherwise it just makes your code harder to read.

const int resultBranchless = aVal * switch + bVal * (1 - switch);
//vs
const int resultWithBranching = switch ? aVal : bVal;

Usually compilers will optimize the second one to a cmov or similar instruction, which is as close to fast branching as it can (except cfmov on older x86 CPUs), and is DSP compatible.

[-] AnUnusualRelic@lemmy.world 5 points 1 year ago* (last edited 1 year ago)

if branchless goto nobranch    
else return

this post was submitted on 10 Jul 2023

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