6b056f929d
The high byte of a long variable on a 64-bit platform is now zeroed when it is pushed to stack. Reviewed-by: coleenp, dlong
100 lines
4.0 KiB
Java
100 lines
4.0 KiB
Java
/*
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* Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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import java.lang.reflect.Field;
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import java.lang.reflect.Method;
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import java.util.List;
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import java.util.Set;
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import java.util.stream.Collectors;
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import java.lang.StackWalker.StackFrame;
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public class LocalLongHelper {
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static StackWalker sw;
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static Method intValue;
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static Method getLocals;
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static Class<?> primitiveValueClass;
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static Method primitiveType;
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static Method getMethodType;
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static Field memberName;
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static Field offset;
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public static void main(String[] args) throws Throwable {
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setupReflectionStatics();
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new LocalLongHelper().longArg(0xC0FFEE, 0x1234567890ABCDEFL);
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}
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// locals[2] contains the high byte of the long argument.
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public long longArg(int i, long l) throws Throwable {
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List<StackFrame> frames = sw.walk(s -> s.collect(Collectors.toList()));
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Object[] locals = (Object[]) getLocals.invoke(frames.get(0));
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int locals_2 = (int) intValue.invoke(locals[2]);
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if (locals_2 != 0){
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throw new RuntimeException("Expected locals_2 == 0");
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}
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return l; // Don't want l to become a dead var
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}
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private static void setupReflectionStatics() throws Throwable {
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Class<?> liveStackFrameClass = Class.forName("java.lang.LiveStackFrame");
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primitiveValueClass = Class.forName("java.lang.LiveStackFrame$PrimitiveValue");
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getLocals = liveStackFrameClass.getDeclaredMethod("getLocals");
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getLocals.setAccessible(true);
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intValue = primitiveValueClass.getDeclaredMethod("intValue");
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intValue.setAccessible(true);
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Class<?> stackFrameInfoClass = Class.forName("java.lang.StackFrameInfo");
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memberName = stackFrameInfoClass.getDeclaredField("memberName");
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memberName.setAccessible(true);
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offset = stackFrameInfoClass.getDeclaredField("bci");
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offset.setAccessible(true);
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getMethodType = Class.forName("java.lang.invoke.MemberName").getDeclaredMethod("getMethodType");
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getMethodType.setAccessible(true);
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Class<?> extendedOptionClass = Class.forName("java.lang.StackWalker$ExtendedOption");
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Method ewsNI = StackWalker.class.getDeclaredMethod("newInstance", Set.class, extendedOptionClass);
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ewsNI.setAccessible(true);
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Field f = extendedOptionClass.getDeclaredField("LOCALS_AND_OPERANDS");
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f.setAccessible(true);
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Object localsAndOperandsOption = f.get(null);
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primitiveType = primitiveValueClass.getDeclaredMethod("type");
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primitiveType.setAccessible(true);
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sw = (StackWalker) ewsNI.invoke(null, java.util.Collections.emptySet(), localsAndOperandsOption);
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}
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private static String type(Object o) throws Throwable {
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if (primitiveValueClass.isInstance(o)) {
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final char c = (char) primitiveType.invoke(o);
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return String.valueOf(c);
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} else if (o != null) {
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return o.getClass().getName();
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} else {
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return "null";
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}
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}
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}
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