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23 
24 package compiler.uncommontrap;
25 
26 /**
27  * @test
28  * @bug 8261730 8265132
29  * @summary Test that no anti-dependence violation is reported between a store
30  *          used as an implicit null check and a load placed in the null block.
31  * @run main/othervm -XX:-BackgroundCompilation
32  *      compiler.uncommontrap.TestNullCheckAntiDependence
33  */
34 
35 public class TestNullCheckAntiDependence {
36 
37     private static class MyInteger {
38         int val;
39     }
40 
41     private static MyInteger foo = new MyInteger();
42     private static MyInteger bar = new MyInteger();
43     private static MyInteger[] global = {new MyInteger()};
44 
test1()45     static void test1() {
46         for (int i = 0; i < 1; i++) {
47             // This load is placed in the null block.
48             foo.val = -bar.val;
49             for (int k = 0; k < 10; k++) {
50                 // This store is hoisted and used as an implicit null check.
51                 foo.val = 0;
52             }
53         }
54     }
55 
test2(MyInteger a, MyInteger b)56     static void test2(MyInteger a, MyInteger b) {
57         global[0].val = a.val + b.val * 31;
58         global[0].val = 0;
59         return;
60     }
61 
main(String[] args)62     public static void main(String[] args) {
63         for (int i = 0; i < 10_000; i++) {
64             test1();
65         }
66 
67         for (int i = 0; i < 10_000; i++) {
68             test2(new MyInteger(), new MyInteger());
69         }
70 
71     }
72 
73 }
74