The Weird Concept of Branchless Programming

I kind of like branchless programming, because in SIMD programming, some of its concepts are directly borrowed from branchless techniques, for example using bit masks to represent which vector to enable scatter and gather for.

For example, I can give it an array A and a vector V and a mask which output another vector O, then if the specific position i in the bit mask is 1, then O[i] will pick this element from A[V[i]], otherwise just A[i].

In Python this may sound like [A[V[i]] if M[i] else V[i] for i in range(len(V))], so it is very branchy, but in SIMD this would just be a bunch of SIMD operations without branch!

Speaking of which, this is particularly informative about what "branchless programming" really are: https://en.m.wikipedia.org/wiki/Predication_(computer_archit...

If you want to learn about the ultimate form of branchless programming, check out Church encoding: https://en.m.wikipedia.org/wiki/Church_encoding and https://gautier.difolco.dev/2025-09/extreme-branchless-expr-...