/* * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /* * @test * @bug 8200698 * @summary Tests that exceptions are thrown for ops which would overflow * @requires (sun.arch.data.model == "64" & os.maxMemory > 4g) * @run testng/othervm -Xmx4g LargeValueExceptions */ import java.math.BigInteger; import static java.math.BigInteger.ONE; import org.testng.annotations.Test; // // The intent of this test is to probe the boundaries between overflow and // non-overflow, principally for multiplication and squaring, specifically // the largest values which should not overflow and the smallest values which // should. The transition values used are not necessarily at the exact // boundaries but should be "close." Quite a few different values were used // experimentally before settling on the ones in this test. For multiplication // and squaring all cases are exercised: definite overflow and non-overflow // which can be detected "up front," and "indefinite" overflow, i.e., overflow // which cannot be detected up front so further calculations are required. // // Testing negative values is unnecessary. For both multiplication and squaring // the paths lead to the Toom-Cook algorithm where the signum is used only to // determine the sign of the result and not in the intermediate calculations. // This is also true for exponentiation. // // @Test annotations with optional element "enabled" set to "false" should // succeed when "enabled" is set to "true" but they take too to run in the // course of the typical regression test execution scenario. // public class LargeValueExceptions { // BigInteger.MAX_MAG_LENGTH private static final int MAX_INTS = 1 << 26; // Number of bits corresponding to MAX_INTS private static final long MAX_BITS = (0xffffffffL & MAX_INTS) << 5L; // Half BigInteger.MAX_MAG_LENGTH private static final int MAX_INTS_HALF = MAX_INTS / 2; // --- squaring --- // Largest no overflow determined by examining data lengths alone. @Test(enabled=false) public void squareNoOverflow() { BigInteger x = ONE.shiftLeft(16*MAX_INTS - 1).subtract(ONE); BigInteger y = x.multiply(x); } // Smallest no overflow determined by extra calculations. @Test(enabled=false) public void squareIndefiniteOverflowSuccess() { BigInteger x = ONE.shiftLeft(16*MAX_INTS - 1); BigInteger y = x.multiply(x); } // Largest overflow detected by extra calculations. @Test(expectedExceptions=ArithmeticException.class,enabled=false) public void squareIndefiniteOverflowFailure() { BigInteger x = ONE.shiftLeft(16*MAX_INTS).subtract(ONE); BigInteger y = x.multiply(x); } // Smallest overflow detected by examining data lengths alone. @Test(expectedExceptions=ArithmeticException.class) public void squareDefiniteOverflow() { BigInteger x = ONE.shiftLeft(16*MAX_INTS); BigInteger y = x.multiply(x); } // --- multiplication --- // Largest no overflow determined by examining data lengths alone. @Test(enabled=false) public void multiplyNoOverflow() { final int halfMaxBits = MAX_INTS_HALF << 5; BigInteger x = ONE.shiftLeft(halfMaxBits).subtract(ONE); BigInteger y = ONE.shiftLeft(halfMaxBits - 1).subtract(ONE); BigInteger z = x.multiply(y); } // Smallest no overflow determined by extra calculations. @Test(enabled=false) public void multiplyIndefiniteOverflowSuccess() { BigInteger x = ONE.shiftLeft((int)(MAX_BITS/2) - 1); long m = MAX_BITS - x.bitLength(); BigInteger y = ONE.shiftLeft((int)(MAX_BITS/2) - 1); long n = MAX_BITS - y.bitLength(); if (m + n != MAX_BITS) { throw new RuntimeException("Unexpected leading zero sum"); } BigInteger z = x.multiply(y); } // Largest overflow detected by extra calculations. @Test(expectedExceptions=ArithmeticException.class,enabled=false) public void multiplyIndefiniteOverflowFailure() { BigInteger x = ONE.shiftLeft((int)(MAX_BITS/2)).subtract(ONE); long m = MAX_BITS - x.bitLength(); BigInteger y = ONE.shiftLeft((int)(MAX_BITS/2)).subtract(ONE); long n = MAX_BITS - y.bitLength(); if (m + n != MAX_BITS) { throw new RuntimeException("Unexpected leading zero sum"); } BigInteger z = x.multiply(y); } // Smallest overflow detected by examining data lengths alone. @Test(expectedExceptions=ArithmeticException.class) public void multiplyDefiniteOverflow() { // multiply by 4 as MAX_INTS_HALF refers to ints byte[] xmag = new byte[4*MAX_INTS_HALF]; xmag[0] = (byte)0xff; BigInteger x = new BigInteger(1, xmag); byte[] ymag = new byte[4*MAX_INTS_HALF + 1]; ymag[0] = (byte)0xff; BigInteger y = new BigInteger(1, ymag); BigInteger z = x.multiply(y); } // --- exponentiation --- @Test(expectedExceptions=ArithmeticException.class) public void powOverflow() { BigInteger.TEN.pow(Integer.MAX_VALUE); } @Test(expectedExceptions=ArithmeticException.class) public void powOverflow1() { int shift = 20; int exponent = 1 << shift; BigInteger x = ONE.shiftLeft((int)(MAX_BITS / exponent)); BigInteger y = x.pow(exponent); } @Test(expectedExceptions=ArithmeticException.class) public void powOverflow2() { int shift = 20; int exponent = 1 << shift; BigInteger x = ONE.shiftLeft((int)(MAX_BITS / exponent)).add(ONE); BigInteger y = x.pow(exponent); } @Test(expectedExceptions=ArithmeticException.class,enabled=false) public void powOverflow3() { int shift = 20; int exponent = 1 << shift; BigInteger x = ONE.shiftLeft((int)(MAX_BITS / exponent)).subtract(ONE); BigInteger y = x.pow(exponent); } @Test(enabled=false) public void powOverflow4() { int shift = 20; int exponent = 1 << shift; BigInteger x = ONE.shiftLeft((int)(MAX_BITS / exponent - 1)).add(ONE); BigInteger y = x.pow(exponent); } }