What is faster (x < 0) or (x == -1)?

Question

Variable x is int with possible values: -1, 0, 1, 2, 3. Which expression will be faster (in CPU ticks):

1. (x < 0)
2. (x == -1)
         


        

Answer 1

You can't even answer this question out of context. If you try for a trivial microbenchmark, it's entirely possible that the optimizer will waft your code into the ether:

// Get time
int x = -1;
for (int i = 0; i < ONE_JILLION; i++) {
    int dummy = (x < 0); // Poof!  Dummy is ignored.
}
// Compute time difference - in the presence of good optimization
// expect this time difference to be close to useless.