this post was submitted on 10 Jul 2023
72 points (97.4% liked)

Programming

17021 readers
378 users here now

Welcome to the main community in programming.dev! Feel free to post anything relating to programming here!

Cross posting is strongly encouraged in the instance. If you feel your post or another person's post makes sense in another community cross post into it.

Hope you enjoy the instance!

Rules

Rules

  • Follow the programming.dev instance rules
  • Keep content related to programming in some way
  • If you're posting long videos try to add in some form of tldr for those who don't want to watch videos

Wormhole

Follow the wormhole through a path of communities [email protected]

founded 1 year ago
MODERATORS
snowe
Ategon
[email protected]
72
How often does branchless programming actually matter? (self.programming)
submitted 1 year ago by firelizzard to c/programming
48 comments fedilink hide all child comments
 

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?

you are viewing a single comment's thread
view the rest of the comments
[โ€“] [email protected] 8 points 1 year ago (1 children)

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.

[โ€“] [email protected] 5 points 1 year ago* (last edited 1 year ago) 
if branchless goto nobranch    
else return