CountedLoopProblem.java

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/**
 * @test
 * @bug 8072753
 * @summary Inner loop induction variable increment occurs before compare which causes integer overflow
 * @run main/othervm compiler.loopopts.CountedLoopProblem
 *
 */

package compiler.loopopts;

import java.util.Random;

public class CountedLoopProblem {
    public static void main(String[] args) throws Exception {
        Random r = new Random(42);
        int x = 0;
        try {
            StringBuilder sb = new StringBuilder();
            for(int i = 0; i < 1000000; ++i) {
                int v = Math.abs(r.nextInt());
                sb.append('+').append(v).append('\n');
                x += v;
                // To trigger the problem we must OSR in the following loop
                // To make the problem 100% reproducible run with -XX:-TieredCompilation -XX:OSROnlyBCI=62
                while(x < 0) x += 1000000000;
                sb.append('=').append(x).append('\n');
            }
            if (sb.toString().hashCode() != 0xaba94591) {
                throw new Exception("Unexpected result");
            }
        } catch(OutOfMemoryError e) {
            // small heap, ignore
        }
    }
}