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1 /*
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2 * Copyright 2001-2003 Sun Microsystems, Inc. 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.interpreter;
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26
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27 import sun.jvm.hotspot.oops.*;
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28 import sun.jvm.hotspot.utilities.*;
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29
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30 public class BytecodeTableswitch extends Bytecode {
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31 BytecodeTableswitch(Method method, int bci) {
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32 super(method, bci);
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33 }
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34
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35
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36 // Attributes
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37 public int defaultOffset() { return javaSignedWordAt(alignedOffset(1 + 0*jintSize)); }
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38 public int lowKey() { return javaSignedWordAt(alignedOffset(1 + 1*jintSize)); }
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39 public int highKey() { return javaSignedWordAt(alignedOffset(1 + 2*jintSize)); }
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40 public int length() { return highKey()-lowKey()+1; }
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41 public int destOffsetAt(int i) {
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42 int x2 = alignedOffset(1 + (3 + i)*jintSize);
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43 int val = javaSignedWordAt(x2);
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44 return javaSignedWordAt(alignedOffset(1 + (3 + i)*jintSize));
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45 }
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46
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47 public void verify() {
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48 if (Assert.ASSERTS_ENABLED) {
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49 Assert.that(isValid(), "check tableswitch");
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50 }
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51 }
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52
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53 public boolean isValid() {
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54 boolean result = javaCode() == Bytecodes._tableswitch;
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55 if (result == false) return false;
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56 int lo = lowKey();
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57 int hi = highKey();
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58 if (hi < lo) // incorrect hi/lo values in tableswitch
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59 return false;
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60
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61 int i = hi - lo - 1 ;
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62 while (i-- > 0) {
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63 // no special check needed
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64 }
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65 return true;
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66 }
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67
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68 public static BytecodeTableswitch at(Method method, int bci) {
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69 BytecodeTableswitch b = new BytecodeTableswitch(method, bci);
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70 if (Assert.ASSERTS_ENABLED) {
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71 b.verify();
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72 }
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73 return b;
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74 }
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75
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76 /** Like at, but returns null if the BCI is not at tableswitch */
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77 public static BytecodeTableswitch atCheck(Method method, int bci) {
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78 BytecodeTableswitch b = new BytecodeTableswitch(method, bci);
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79 return (b.isValid() ? b : null);
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80 }
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81
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82 public static BytecodeTableswitch at(BytecodeStream bcs) {
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83 return new BytecodeTableswitch(bcs.method(), bcs.bci());
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84 }
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85
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86 public String toString() {
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87 StringBuffer buf = new StringBuffer();
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88 buf.append("tableswitch");
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89 buf.append(spaces);
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90 buf.append("default: ");
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91 buf.append(Integer.toString(bci() + defaultOffset()));
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92 buf.append(comma);
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93 int lo = lowKey();
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94 int hi = highKey();
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95 int i = hi - lo - 1 ;
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96 while (i-- > 0) {
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97 buf.append("case ");
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98 buf.append(Integer.toString(lo + i));
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99 buf.append(':');
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100 buf.append(Integer.toString(bci() + destOffsetAt(i)));
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101 buf.append(comma);
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102 }
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103 return buf.toString();
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104 }
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105 }
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