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

It could be dependent on what operations precede or succeed the comparison. For example, if you assign a value to x just before doing the comparison, then it might be faster to check the sign flag than to compare to a specific value. Or the CPU's branch-prediction performance could be affected by which comparison you choose.

But, as others have said, this is dependent upon CPU architecture, memory architecture, compiler, and a lot of other things, so there is no general answer.