What techniques to avoid conditional branching do you know?

Question

Sometimes a loop where the CPU spends most of the time has some branch prediction miss (misprediction) very often (near .5 probability.) I've seen a few techniques on very isolated threads but never a list. The ones I know already fix situations where the condition can be turned to a bool and that 0/1 is used in some way to change. Are there other conditional branches that can be avoided?

e.g. (pseudocode)

loop () {   if (in[i] < C )     out[o++] = in[i++]   ... } 

Can be rewritten, arguably losing some readability, with something like this:

loop() {   out[o] = in[i]  // copy anyway, just don't increment   inc = in[i] < C  // increment counters? (0 or 1)   o += inc   i += inc } 

Also I've seen techniques in the wild changing && to & in the conditional in certain contexts escaping my mind right now. I'm a rookie at this level of optimization but it sure feels like there's got to be more.

Answer 1

Using Matt Joiner's example:

if (b > a) b = a; 

You could also do the following, without having to dig into assembly code:

bool if_else = b > a; b = a * if_else + b * !if_else;