1 /* 2 * Copyright (c) 2011, 2012, 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.meta; 24 25 import java.util.IdentityHashMap; 26 27 // JaCoCo Exclude 28 29 /** 30 * Marker interface for location identities. A different location identity of two memory accesses 31 * guarantees that the two accesses do not interfere. 32 * 33 * Clients of {@link LocationIdentity} must use {@link #equals(Object)}, not {@code ==}, when 34 * comparing two {@link LocationIdentity} values for equality. Likewise, they must not use 35 * {@link IdentityHashMap}s with {@link LocationIdentity} values as keys. 36 */ 37 public abstract class LocationIdentity { 38 39 private static final class AnyLocationIdentity extends LocationIdentity { 40 @Override 41 public boolean isImmutable() { 42 return false; 43 } 44 45 @Override 46 public String toString() { 47 return "ANY_LOCATION"; 48 } 49 } 50 51 public static final LocationIdentity ANY_LOCATION = new AnyLocationIdentity(); 52 53 public static LocationIdentity any() { 54 return ANY_LOCATION; 55 } 56 57 /** 58 * Denotes a location is unchanging in all cases. Not that this is different than the Java 59 * notion of final which only requires definite assignment. 60 */ 61 public abstract boolean isImmutable(); 62 63 public final boolean isMutable() { 64 return !isImmutable(); 65 } 66 67 public final boolean isAny() { 68 return this == ANY_LOCATION; 69 } 70 71 public final boolean isSingle() { 72 return this != ANY_LOCATION; 73 } 74 75 public final boolean overlaps(LocationIdentity other) { 76 return isAny() || other.isAny() || this.equals(other); 77 } 78 }