test/hotspot/jtreg/compiler/loopopts/TestOneIterationStripMined.java

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/*
 * @test
 * @bug 8208275
 * @summary Test removal of strip mined loop with only one iteration.
 * @run main/othervm -XX:-TieredCompilation -Xcomp
 *                   -XX:CompileCommand=compileonly,compiler.loopopts.TestOneIterationStripMined::test*
 *                   compiler.loopopts.TestOneIterationStripMined
 */

package compiler.loopopts;

public class TestOneIterationStripMined {
    static int iField;
    static volatile Object oField;

    public static void test1(int val) {
        iField = 0; // Do something
        // This loop is strip mined and then removed because it has only one iteration.
        for (int i = 0; i < 1; ++i) {
            // Trigger split-if optimization
            if (val == 0) {
                break;
            }
            val = 0;
        }
    }

    // Same as test1 but with a volatile Object field
    // (will trigger a different failure mode)
    public static void test2(int val) {
        oField = null;
        for (int i = 0; i < 1; ++i) {
            if (val == 0) {
                break;
            }
            val = 0;
        }
    }

    // Same as test1 but without any code outside loop body
    // (will trigger a different failure mode)
    public static void test3(int val) {
        for (int i = 0; i < 1; ++i) {
            if (val == 0) {
                break;
            }
            val = 0;
        }
    }

    public static void main(String[] args) {
        test1(0);
        test2(0);
        test3(0);
    }
}