1 /* 2 * Copyright (c) 2011, 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 20 * CA 95054 USA or visit www.sun.com if you need additional information or 21 * have any questions. 22 * 23 */ 24 25 package sun.jvm.hotspot.oops; 26 27 import java.io.*; 28 import java.util.*; 29 import sun.jvm.hotspot.debugger.*; 30 import sun.jvm.hotspot.runtime.*; 31 import sun.jvm.hotspot.types.*; 32 import sun.jvm.hotspot.utilities.*; 33 34 // BitData 35 // 36 // A BitData holds a flag or two in its header. 37 public class BitData extends ProfileData { 38 39 // nullSeen: 40 // saw a null operand (cast/aastore/instanceof) 41 static final int nullSeenFlag = DataLayout.firstFlag + 0; 42 static final int bitCellCount = 0; 43 44 public BitData(DataLayout layout) { 45 super(layout); 46 } 47 48 static int staticCellCount() { 49 return bitCellCount; 50 } 51 52 public int cellCount() { 53 return staticCellCount(); 54 } 55 56 // Accessor 57 58 // The nullSeen flag bit is specially known to the interpreter. 59 // Consulting it allows the compiler to avoid setting up nullCheck traps. 60 boolean nullSeen() { return flagAt(nullSeenFlag); } 61 62 // Code generation support 63 // static int nullSeenByteConstant() { 64 // return flagNumberToByteConstant(nullSeenFlag); 65 // } 66 67 static int bitDataSize() { 68 return cellOffset(bitCellCount); 69 } 70 71 public void printDataOn(PrintStream st) { 72 printShared(st, "BitData"); 73 } 74 }