1 /*
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23 
24 /*
25  * @test
26  * @bug 6910473 8272541
27  * @summary Test that bitLength() is not negative
28  * @author Dmitry Nadezhin
29  */
30 package test.java.math.BigInteger;
31 
32 import java.math.BigInteger;
33 import java.util.function.Supplier;
34 
35 public class BitLengthOverflow {
test(Supplier<BigInteger> s)36     private static void test(Supplier<BigInteger> s) {
37         try {
38             BigInteger x = s.get();
39             System.out.println("Surprisingly passed with correct bitLength() " +
40                                x.bitLength());
41         } catch (ArithmeticException e) {
42             // expected
43             System.out.println("Overflow reported by ArithmeticException, as expected");
44         } catch (OutOfMemoryError e) {
45             // possible
46             System.err.println("BitLengthOverflow skipped: OutOfMemoryError");
47             System.err.println("Run jtreg with -javaoption:-Xmx8g");
48         }
49     }
50 
main(String[] args)51     public static void main(String[] args) {
52         test(() -> {
53             // x = pow(2,Integer.MAX_VALUE)
54             BigInteger x = BigInteger.ONE.shiftLeft(Integer.MAX_VALUE);
55             if (x.bitLength() != (1L << 31)) {
56                 throw new RuntimeException("Incorrect bitLength() " +
57                                            x.bitLength());
58             }
59             return x;
60         });
61         test(() -> {
62             BigInteger a = BigInteger.ONE.shiftLeft(1073742825);
63             BigInteger b = BigInteger.ONE.shiftLeft(1073742825);
64             return a.multiply(b);
65         });
66     }
67 }
68