1 /* 2 * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 package jdk.vm.ci.hotspot; 24 25 import static jdk.vm.ci.hotspot.HotSpotJVMCIRuntime.runtime; 26 27 import jdk.vm.ci.meta.JavaConstant; 28 29 final class IndirectHotSpotObjectConstantImpl extends HotSpotObjectConstantImpl { 30 /** 31 * An object handle in {@code JVMCI::_jvmci_handles}. 32 */ 33 final long objectHandle; 34 private int hashCode; 35 36 final IndirectHotSpotObjectConstantImpl base; 37 38 @VMEntryPoint 39 private IndirectHotSpotObjectConstantImpl(long objectHandle, boolean compressed, boolean skipRegister) { 40 super(compressed); 41 assert objectHandle != 0 && UnsafeAccess.UNSAFE.getLong(objectHandle) != 0; 42 this.objectHandle = objectHandle; 43 this.base = null; 44 if (!skipRegister) { 45 HandleCleaner.create(this, objectHandle); 46 } 47 } 48 49 private IndirectHotSpotObjectConstantImpl(IndirectHotSpotObjectConstantImpl base, boolean compressed) { 50 super(compressed); 51 // This is a variant of an original object that only varies in compress vs uncompressed. 52 // Instead of creating a new handle, reference that object and objectHandle. 53 this.objectHandle = base.objectHandle; 54 // There should only be on level of indirection to the base object. 55 assert base.base == null || base.base.base == null; 56 this.base = base.base != null ? base.base : base; 57 } 58 59 @Override 60 public JavaConstant compress() { 61 assert !compressed; 62 return new IndirectHotSpotObjectConstantImpl(this, true); 63 } 64 65 @Override 66 public JavaConstant uncompress() { 67 assert compressed; 68 return new IndirectHotSpotObjectConstantImpl(this, false); 69 } 70 71 @Override 72 public int getIdentityHashCode() { 73 int hash = hashCode; 74 if (hash == 0) { 75 hash = runtime().compilerToVm.getIdentityHashCode(this); 76 if (hash == 0) { 77 hash = 31; 78 } 79 hashCode = hash; 80 } 81 return hash; 82 } 83 }