Mercurial > hg > graal-jvmci-8
diff graal/com.oracle.truffle.api/src/com/oracle/truffle/api/intrinsics/ExactMath.java @ 7267:a4b84ba6dc2e
Introduction of the Truffle API for efficient implementation of dynamic languages on top of the Graal VM. New projects com.oracle.truffle.api for the API definition and com.oracle.truffle.api.test for API tests and documentation.
author | Thomas Wuerthinger <thomas.wuerthinger@oracle.com> |
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date | Tue, 18 Dec 2012 15:33:55 +0100 |
parents | |
children | 5e3d1a68664e |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/graal/com.oracle.truffle.api/src/com/oracle/truffle/api/intrinsics/ExactMath.java Tue Dec 18 15:33:55 2012 +0100 @@ -0,0 +1,91 @@ +/* + * Copyright (c) 2012, 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. + */ +package com.oracle.truffle.api.intrinsics; + +/** + * This class contains methods that will be part of java.lang.Math starting with JDK 8. Until JDK 8 is release, we + * duplicate them here because they are generally useful for dynamic language implementations. + */ +public class ExactMath { + + public static int addExact(int x, int y) { + int r = x + y; + // HD 2-12 Overflow iff both arguments have the opposite sign of the result + if (((x ^ r) & (y ^ r)) < 0) { + throw new ArithmeticException("integer overflow"); + } + return r; + } + + public static long addExact(long x, long y) { + long r = x + y; + // HD 2-12 Overflow iff both arguments have the opposite sign of the result + if (((x ^ r) & (y ^ r)) < 0) { + throw new ArithmeticException("long overflow"); + } + return r; + } + + public static int subtractExact(int x, int y) { + int r = x - y; + // HD 2-12 Overflow iff the arguments have different signs and + // the sign of the result is different than the sign of x + if (((x ^ y) & (x ^ r)) < 0) { + throw new ArithmeticException("integer overflow"); + } + return r; + } + + public static long subtractExact(long x, long y) { + long r = x - y; + // HD 2-12 Overflow iff the arguments have different signs and + // the sign of the result is different than the sign of x + if (((x ^ y) & (x ^ r)) < 0) { + throw new ArithmeticException("long overflow"); + } + return r; + } + + public static int multiplyExact(int x, int y) { + long r = (long) x * (long) y; + if ((int) r != r) { + throw new ArithmeticException("long overflow"); + } + return (int) r; + } + + public static long multiplyExact(long x, long y) { + long r = x * y; + long ax = Math.abs(x); + long ay = Math.abs(y); + if (((ax | ay) >>> 31 != 0)) { + // Some bits greater than 2^31 that might cause overflow + // Check the result using the divide operator + // and check for the special case of Long.MIN_VALUE * -1 + if (((y != 0) && (r / y != x)) || (x == Long.MIN_VALUE && y == -1)) { + throw new ArithmeticException("long overflow"); + } + } + return r; + } +}