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3939
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1 /*
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2 * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 package sun.jvm.hotspot.oops;
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26
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27 import java.io.*;
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28 import java.util.*;
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29 import sun.jvm.hotspot.debugger.*;
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30 import sun.jvm.hotspot.runtime.*;
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31 import sun.jvm.hotspot.types.*;
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32 import sun.jvm.hotspot.utilities.*;
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33
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34 // BitData
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35 //
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36 // A BitData holds a flag or two in its header.
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37 public class BitData extends ProfileData {
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38
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39 // nullSeen:
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40 // saw a null operand (cast/aastore/instanceof)
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41 static final int nullSeenFlag = DataLayout.firstFlag + 0;
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42 static final int bitCellCount = 0;
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43
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44 public BitData(DataLayout layout) {
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45 super(layout);
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46 }
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47
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48 static int staticCellCount() {
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49 return bitCellCount;
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50 }
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51
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52 public int cellCount() {
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53 return staticCellCount();
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54 }
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55
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56 // Accessor
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57
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58 // The nullSeen flag bit is specially known to the interpreter.
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59 // Consulting it allows the compiler to avoid setting up nullCheck traps.
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60 boolean nullSeen() { return flagAt(nullSeenFlag); }
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61
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62 // Code generation support
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63 // static int nullSeenByteConstant() {
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64 // return flagNumberToByteConstant(nullSeenFlag);
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65 // }
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66
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67 static int bitDataSize() {
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68 return cellOffset(bitCellCount);
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69 }
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70
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71 public void printDataOn(PrintStream st) {
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72 printShared(st, "BitData");
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73 }
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74 }
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