Question

Does the java compiler (the default javac that comes in JDK1.6.0_21) optimize code to prevent the same method from being called with the same arguments over and over? If I wrote this code:

public class FooBar {
    public static void main(String[] args) {
        foo(bar);
        foo(bar);
        foo(bar);
    }
}

Would the method foo(bar) only run once? If so, is there any way to prevent this optimization? (I’m trying to compare runtime for two algos, one iterative and one comparative, and I want to call them a bunch of times to get a representative sample)

Any insight would be much appreciated; I took this problem to the point of insanity (I though my computer was insanely fast for a little while, so I kept on adding method calls until I got the code too large error at 43671 lines).

Answer 1

The optimization you are observing is probably nothing to do with repeated calls … because that would be an invalid optimization. More likely, the optimizer has figured out that the method calls have no observable effect on the computation.

The cure is to change the method so that it does affect the result of computation …