[okaleniuk]

Some safety critical real time systems have strict time predictability requirements. This means that the whole loop should pass in exactly X microsecond, not more not less. For this, all the programming should be pretty much branchless.

For instance, all the sorting algorithm turn to, effectively, bubble sort since without branches, you always go with the worst case - and the sorting complexity is always the O(n^2). But it's okay, since the algorithm becomes predictable. You just swap a conditional swap:

    if a < b then swap(a, b)

with arithmetic swap:

    c = (a+b)/2
    d = |a-b|/2
    a = c + d 
    b = c - d

and that's it.

[ashdnazg]

O(n^2) isn't required. One could do an in-place merge-sort, which is also always worst case, but with O(n*log(n)).

I suspect everyone turns to Bubblesort since the inputs are small enough that it doesn't matter (evident by the fact that it should fit within microseconds).