# HG changeset patch # User rbackman # Date 1516299671 -3600 # Node ID a81c930a8838b1e0333a56c9ae8e419b244f98f0 # Parent 2b0b7f22280075ddd2b5c269a8bf6a8c6eef9dad 8191915: JCK tests produce incorrect results with C2 Reviewed-by: thartmann, vlivanov, goetz diff -r 2b0b7f222800 -r a81c930a8838 src/hotspot/share/opto/mathexactnode.cpp --- a/src/hotspot/share/opto/mathexactnode.cpp Tue Jan 23 14:27:10 2018 -0500 +++ b/src/hotspot/share/opto/mathexactnode.cpp Thu Jan 18 19:21:11 2018 +0100 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2013, 2014, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2013, 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 @@ -117,23 +117,33 @@ return SubHelper::will_overflow(v1, v2); } -bool OverflowMulLNode::will_overflow(jlong val1, jlong val2) const { - jlong result = val1 * val2; - jlong ax = (val1 < 0 ? -val1 : val1); - jlong ay = (val2 < 0 ? -val2 : val2); +bool OverflowMulLNode::is_overflow(jlong val1, jlong val2) { + // x * { 0, 1 } will never overflow. Even for x = min_jlong + if (val1 == 0 || val2 == 0 || val1 == 1 || val2 == 1) { + return false; + } - bool overflow = false; - if ((ax | ay) & CONST64(0xFFFFFFFF00000000)) { - // potential overflow if any bit in upper 32 bits are set - if ((val1 == min_jlong && val2 == -1) || (val2 == min_jlong && val1 == -1)) { - // -1 * Long.MIN_VALUE will overflow - overflow = true; - } else if (val2 != 0 && (result / val2 != val1)) { - overflow = true; - } + // x * min_jlong for x not in { 0, 1 } overflows + // even -1 as -1 * min_jlong is an overflow + if (val1 == min_jlong || val2 == min_jlong) { + return true; } - return overflow; + // if (x * y) / y == x there is no overflow + // + // the multiplication here is done as unsigned to avoid undefined behaviour which + // can be used by the compiler to assume that the check further down (result / val2 != val1) + // is always false and breaks the overflow check + julong v1 = (julong) val1; + julong v2 = (julong) val2; + julong tmp = v1 * v2; + jlong result = (jlong) tmp; + + if (result / val2 != val1) { + return true; + } + + return false; } bool OverflowAddINode::can_overflow(const Type* t1, const Type* t2) const { diff -r 2b0b7f222800 -r a81c930a8838 src/hotspot/share/opto/mathexactnode.hpp --- a/src/hotspot/share/opto/mathexactnode.hpp Tue Jan 23 14:27:10 2018 -0500 +++ b/src/hotspot/share/opto/mathexactnode.hpp Thu Jan 18 19:21:11 2018 +0100 @@ -129,8 +129,10 @@ OverflowMulLNode(Node* in1, Node* in2) : OverflowLNode(in1, in2) {} virtual int Opcode() const; - virtual bool will_overflow(jlong v1, jlong v2) const; + virtual bool will_overflow(jlong v1, jlong v2) const { return is_overflow(v1, v2); } virtual bool can_overflow(const Type* t1, const Type* t2) const; + + static bool is_overflow(jlong v1, jlong v2); }; #endif diff -r 2b0b7f222800 -r a81c930a8838 test/hotspot/gtest/opto/test_mathexact.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/test/hotspot/gtest/opto/test_mathexact.cpp Thu Jan 18 19:21:11 2018 +0100 @@ -0,0 +1,40 @@ +/* + * 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. + * + */ + +#include "precompiled.hpp" +#include "opto/mulnode.hpp" +#include "opto/mathexactnode.hpp" +#include "unittest.hpp" + +TEST_VM(opto, mathexact) { + ASSERT_FALSE(OverflowMulLNode::is_overflow(1, 1)); + ASSERT_FALSE(OverflowMulLNode::is_overflow(1, min_jlong)); + ASSERT_TRUE(OverflowMulLNode::is_overflow(-1, min_jlong)); + ASSERT_FALSE(OverflowMulLNode::is_overflow(-1, max_jlong)); + ASSERT_TRUE(OverflowMulLNode::is_overflow(max_jlong / 2 + 1, 2)); + ASSERT_FALSE(OverflowMulLNode::is_overflow(min_jlong, 0)); + ASSERT_FALSE(OverflowMulLNode::is_overflow(min_jlong + 1, -1)); + ASSERT_TRUE(OverflowMulLNode::is_overflow(min_jlong + 1, 2)); +} + diff -r 2b0b7f222800 -r a81c930a8838 test/hotspot/jtreg/compiler/intrinsics/mathexact/LongMulOverflowTest.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/test/hotspot/jtreg/compiler/intrinsics/mathexact/LongMulOverflowTest.java Thu Jan 18 19:21:11 2018 +0100 @@ -0,0 +1,64 @@ +/* + * 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 8191915 + * @summary Regression test for multiplyExact intrinsic + * @library /test/lib / + * @modules java.base/jdk.internal.misc + * java.management + * + * @run main/othervm -Xcomp -XX:-TieredCompilation compiler.intrinsics.mathexact.LongMulOverflowTest + */ + +package compiler.intrinsics.mathexact; + +public class LongMulOverflowTest { + public static void main(String[] args) { + LongMulOverflowTest test = new LongMulOverflowTest(); + for (int i = 0; i < 10; ++i) { + try { + test.runTest(); + throw new RuntimeException("Error, runTest() did not overflow!"); + } catch (ArithmeticException e) { + // success + } + + try { + test.runTestOverflow(); + throw new RuntimeException("Error, runTestOverflow() did not overflow!"); + } catch (ArithmeticException e) { + // success + } + } + } + + public void runTest() { + java.lang.Math.multiplyExact(Long.MIN_VALUE, 7); + } + + public void runTestOverflow() { + java.lang.Math.multiplyExact((Long.MAX_VALUE / 2) + 1, 2); + } +}