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Java example source code file (Bytecodes.java)

This example Java source code file (Bytecodes.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

bytecodes, for, method, object, observer, runtimeexception, see, string, util

The Bytecodes.java Java example source code

/*
 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

package sun.jvm.hotspot.interpreter;

import java.util.*;
import sun.jvm.hotspot.oops.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.utilities.*;

// Bytecodes specifies all bytecodes used in the VM and
// provides utility functions to get bytecode attributes.

public class Bytecodes {
  public static final int _illegal    =  -1;

  // Java bytecodes
  public static final int _nop                  =   0; // 0x00
  public static final int _aconst_null          =   1; // 0x01
  public static final int _iconst_m1            =   2; // 0x02
  public static final int _iconst_0             =   3; // 0x03
  public static final int _iconst_1             =   4; // 0x04
  public static final int _iconst_2             =   5; // 0x05
  public static final int _iconst_3             =   6; // 0x06
  public static final int _iconst_4             =   7; // 0x07
  public static final int _iconst_5             =   8; // 0x08
  public static final int _lconst_0             =   9; // 0x09
  public static final int _lconst_1             =  10; // 0x0a
  public static final int _fconst_0             =  11; // 0x0b
  public static final int _fconst_1             =  12; // 0x0c
  public static final int _fconst_2             =  13; // 0x0d
  public static final int _dconst_0             =  14; // 0x0e
  public static final int _dconst_1             =  15; // 0x0f
  public static final int _bipush               =  16; // 0x10
  public static final int _sipush               =  17; // 0x11
  public static final int _ldc                  =  18; // 0x12
  public static final int _ldc_w                =  19; // 0x13
  public static final int _ldc2_w               =  20; // 0x14
  public static final int _iload                =  21; // 0x15
  public static final int _lload                =  22; // 0x16
  public static final int _fload                =  23; // 0x17
  public static final int _dload                =  24; // 0x18
  public static final int _aload                =  25; // 0x19
  public static final int _iload_0              =  26; // 0x1a
  public static final int _iload_1              =  27; // 0x1b
  public static final int _iload_2              =  28; // 0x1c
  public static final int _iload_3              =  29; // 0x1d
  public static final int _lload_0              =  30; // 0x1e
  public static final int _lload_1              =  31; // 0x1f
  public static final int _lload_2              =  32; // 0x20
  public static final int _lload_3              =  33; // 0x21
  public static final int _fload_0              =  34; // 0x22
  public static final int _fload_1              =  35; // 0x23
  public static final int _fload_2              =  36; // 0x24
  public static final int _fload_3              =  37; // 0x25
  public static final int _dload_0              =  38; // 0x26
  public static final int _dload_1              =  39; // 0x27
  public static final int _dload_2              =  40; // 0x28
  public static final int _dload_3              =  41; // 0x29
  public static final int _aload_0              =  42; // 0x2a
  public static final int _aload_1              =  43; // 0x2b
  public static final int _aload_2              =  44; // 0x2c
  public static final int _aload_3              =  45; // 0x2d
  public static final int _iaload               =  46; // 0x2e
  public static final int _laload               =  47; // 0x2f
  public static final int _faload               =  48; // 0x30
  public static final int _daload               =  49; // 0x31
  public static final int _aaload               =  50; // 0x32
  public static final int _baload               =  51; // 0x33
  public static final int _caload               =  52; // 0x34
  public static final int _saload               =  53; // 0x35
  public static final int _istore               =  54; // 0x36
  public static final int _lstore               =  55; // 0x37
  public static final int _fstore               =  56; // 0x38
  public static final int _dstore               =  57; // 0x39
  public static final int _astore               =  58; // 0x3a
  public static final int _istore_0             =  59; // 0x3b
  public static final int _istore_1             =  60; // 0x3c
  public static final int _istore_2             =  61; // 0x3d
  public static final int _istore_3             =  62; // 0x3e
  public static final int _lstore_0             =  63; // 0x3f
  public static final int _lstore_1             =  64; // 0x40
  public static final int _lstore_2             =  65; // 0x41
  public static final int _lstore_3             =  66; // 0x42
  public static final int _fstore_0             =  67; // 0x43
  public static final int _fstore_1             =  68; // 0x44
  public static final int _fstore_2             =  69; // 0x45
  public static final int _fstore_3             =  70; // 0x46
  public static final int _dstore_0             =  71; // 0x47
  public static final int _dstore_1             =  72; // 0x48
  public static final int _dstore_2             =  73; // 0x49
  public static final int _dstore_3             =  74; // 0x4a
  public static final int _astore_0             =  75; // 0x4b
  public static final int _astore_1             =  76; // 0x4c
  public static final int _astore_2             =  77; // 0x4d
  public static final int _astore_3             =  78; // 0x4e
  public static final int _iastore              =  79; // 0x4f
  public static final int _lastore              =  80; // 0x50
  public static final int _fastore              =  81; // 0x51
  public static final int _dastore              =  82; // 0x52
  public static final int _aastore              =  83; // 0x53
  public static final int _bastore              =  84; // 0x54
  public static final int _castore              =  85; // 0x55
  public static final int _sastore              =  86; // 0x56
  public static final int _pop                  =  87; // 0x57
  public static final int _pop2                 =  88; // 0x58
  public static final int _dup                  =  89; // 0x59
  public static final int _dup_x1               =  90; // 0x5a
  public static final int _dup_x2               =  91; // 0x5b
  public static final int _dup2                 =  92; // 0x5c
  public static final int _dup2_x1              =  93; // 0x5d
  public static final int _dup2_x2              =  94; // 0x5e
  public static final int _swap                 =  95; // 0x5f
  public static final int _iadd                 =  96; // 0x60
  public static final int _ladd                 =  97; // 0x61
  public static final int _fadd                 =  98; // 0x62
  public static final int _dadd                 =  99; // 0x63
  public static final int _isub                 = 100; // 0x64
  public static final int _lsub                 = 101; // 0x65
  public static final int _fsub                 = 102; // 0x66
  public static final int _dsub                 = 103; // 0x67
  public static final int _imul                 = 104; // 0x68
  public static final int _lmul                 = 105; // 0x69
  public static final int _fmul                 = 106; // 0x6a
  public static final int _dmul                 = 107; // 0x6b
  public static final int _idiv                 = 108; // 0x6c
  public static final int _ldiv                 = 109; // 0x6d
  public static final int _fdiv                 = 110; // 0x6e
  public static final int _ddiv                 = 111; // 0x6f
  public static final int _irem                 = 112; // 0x70
  public static final int _lrem                 = 113; // 0x71
  public static final int _frem                 = 114; // 0x72
  public static final int _drem                 = 115; // 0x73
  public static final int _ineg                 = 116; // 0x74
  public static final int _lneg                 = 117; // 0x75
  public static final int _fneg                 = 118; // 0x76
  public static final int _dneg                 = 119; // 0x77
  public static final int _ishl                 = 120; // 0x78
  public static final int _lshl                 = 121; // 0x79
  public static final int _ishr                 = 122; // 0x7a
  public static final int _lshr                 = 123; // 0x7b
  public static final int _iushr                = 124; // 0x7c
  public static final int _lushr                = 125; // 0x7d
  public static final int _iand                 = 126; // 0x7e
  public static final int _land                 = 127; // 0x7f
  public static final int _ior                  = 128; // 0x80
  public static final int _lor                  = 129; // 0x81
  public static final int _ixor                 = 130; // 0x82
  public static final int _lxor                 = 131; // 0x83
  public static final int _iinc                 = 132; // 0x84
  public static final int _i2l                  = 133; // 0x85
  public static final int _i2f                  = 134; // 0x86
  public static final int _i2d                  = 135; // 0x87
  public static final int _l2i                  = 136; // 0x88
  public static final int _l2f                  = 137; // 0x89
  public static final int _l2d                  = 138; // 0x8a
  public static final int _f2i                  = 139; // 0x8b
  public static final int _f2l                  = 140; // 0x8c
  public static final int _f2d                  = 141; // 0x8d
  public static final int _d2i                  = 142; // 0x8e
  public static final int _d2l                  = 143; // 0x8f
  public static final int _d2f                  = 144; // 0x90
  public static final int _i2b                  = 145; // 0x91
  public static final int _i2c                  = 146; // 0x92
  public static final int _i2s                  = 147; // 0x93
  public static final int _lcmp                 = 148; // 0x94
  public static final int _fcmpl                = 149; // 0x95
  public static final int _fcmpg                = 150; // 0x96
  public static final int _dcmpl                = 151; // 0x97
  public static final int _dcmpg                = 152; // 0x98
  public static final int _ifeq                 = 153; // 0x99
  public static final int _ifne                 = 154; // 0x9a
  public static final int _iflt                 = 155; // 0x9b
  public static final int _ifge                 = 156; // 0x9c
  public static final int _ifgt                 = 157; // 0x9d
  public static final int _ifle                 = 158; // 0x9e
  public static final int _if_icmpeq            = 159; // 0x9f
  public static final int _if_icmpne            = 160; // 0xa0
  public static final int _if_icmplt            = 161; // 0xa1
  public static final int _if_icmpge            = 162; // 0xa2
  public static final int _if_icmpgt            = 163; // 0xa3
  public static final int _if_icmple            = 164; // 0xa4
  public static final int _if_acmpeq            = 165; // 0xa5
  public static final int _if_acmpne            = 166; // 0xa6
  public static final int _goto                 = 167; // 0xa7
  public static final int _jsr                  = 168; // 0xa8
  public static final int _ret                  = 169; // 0xa9
  public static final int _tableswitch          = 170; // 0xaa
  public static final int _lookupswitch         = 171; // 0xab
  public static final int _ireturn              = 172; // 0xac
  public static final int _lreturn              = 173; // 0xad
  public static final int _freturn              = 174; // 0xae
  public static final int _dreturn              = 175; // 0xaf
  public static final int _areturn              = 176; // 0xb0
  public static final int _return               = 177; // 0xb1
  public static final int _getstatic            = 178; // 0xb2
  public static final int _putstatic            = 179; // 0xb3
  public static final int _getfield             = 180; // 0xb4
  public static final int _putfield             = 181; // 0xb5
  public static final int _invokevirtual        = 182; // 0xb6
  public static final int _invokespecial        = 183; // 0xb7
  public static final int _invokestatic         = 184; // 0xb8
  public static final int _invokeinterface      = 185; // 0xb9
  public static final int _invokedynamic        = 186; // 0xba
  public static final int _new                  = 187; // 0xbb
  public static final int _newarray             = 188; // 0xbc
  public static final int _anewarray            = 189; // 0xbd
  public static final int _arraylength          = 190; // 0xbe
  public static final int _athrow               = 191; // 0xbf
  public static final int _checkcast            = 192; // 0xc0
  public static final int _instanceof           = 193; // 0xc1
  public static final int _monitorenter         = 194; // 0xc2
  public static final int _monitorexit          = 195; // 0xc3
  public static final int _wide                 = 196; // 0xc4
  public static final int _multianewarray       = 197; // 0xc5
  public static final int _ifnull               = 198; // 0xc6
  public static final int _ifnonnull            = 199; // 0xc7
  public static final int _goto_w               = 200; // 0xc8
  public static final int _jsr_w                = 201; // 0xc9
  public static final int _breakpoint           = 202; // 0xca

  public static final int number_of_java_codes  = 203;

  // JVM bytecodes
  public static final int _fast_agetfield       = number_of_java_codes;
  public static final int _fast_bgetfield       = 204;
  public static final int _fast_cgetfield       = 205;
  public static final int _fast_dgetfield       = 206;
  public static final int _fast_fgetfield       = 207;
  public static final int _fast_igetfield       = 208;
  public static final int _fast_lgetfield       = 209;
  public static final int _fast_sgetfield       = 210;
  public static final int _fast_aputfield       = 211;
  public static final int _fast_bputfield       = 212;
  public static final int _fast_cputfield       = 213;
  public static final int _fast_dputfield       = 214;
  public static final int _fast_fputfield       = 215;
  public static final int _fast_iputfield       = 216;
  public static final int _fast_lputfield       = 217;
  public static final int _fast_sputfield       = 218;
  public static final int _fast_aload_0         = 219;
  public static final int _fast_iaccess_0       = 220;
  public static final int _fast_aaccess_0       = 221;
  public static final int _fast_faccess_0       = 222;
  public static final int _fast_iload           = 223;
  public static final int _fast_iload2          = 224;
  public static final int _fast_icaload         = 225;
  public static final int _fast_invokevfinal    = 226;
  public static final int _fast_linearswitch    = 227;
  public static final int _fast_binaryswitch    = 228;
  public static final int _fast_aldc            = 229;
  public static final int _fast_aldc_w          = 230;
  public static final int _return_register_finalizer = 231;
  public static final int _invokehandle         = 232;
  public static final int _shouldnotreachhere   = 233; // For debugging

  public static final int number_of_codes       = 234;

  // Flag bits derived from format strings, can_trap, can_rewrite, etc.:
  // semantic flags:
  static final int  _bc_can_trap      = 1<<0;     // bytecode execution can trap or block
  static final int  _bc_can_rewrite   = 1<<1;     // bytecode execution has an alternate form

  // format bits (determined only by the format string):
  static final int  _fmt_has_c        = 1<<2;     // constant, such as sipush "bcc"
  static final int  _fmt_has_j        = 1<<3;     // constant pool cache index, such as getfield "bjj"
  static final int  _fmt_has_k        = 1<<4;     // constant pool index, such as ldc "bk"
  static final int  _fmt_has_i        = 1<<5;     // local index, such as iload
  static final int  _fmt_has_o        = 1<<6;     // offset, such as ifeq
  static final int  _fmt_has_nbo      = 1<<7;     // contains native-order field(s)
  static final int  _fmt_has_u2       = 1<<8;     // contains double-byte field(s)
  static final int  _fmt_has_u4       = 1<<9;     // contains quad-byte field
  static final int  _fmt_not_variable = 1<<10;    // not of variable length (simple or wide)
  static final int  _fmt_not_simple   = 1<<11;    // either wide or variable length
  static final int  _all_fmt_bits     = (_fmt_not_simple*2 - _fmt_has_c);

  // Example derived format syndromes:
  static final int  _fmt_b      = _fmt_not_variable;
  static final int  _fmt_bc     = _fmt_b | _fmt_has_c;
  static final int  _fmt_bi     = _fmt_b | _fmt_has_i;
  static final int  _fmt_bkk    = _fmt_b | _fmt_has_k | _fmt_has_u2;
  static final int  _fmt_bJJ    = _fmt_b | _fmt_has_j | _fmt_has_u2 | _fmt_has_nbo;
  static final int  _fmt_bo2    = _fmt_b | _fmt_has_o | _fmt_has_u2;
  static final int  _fmt_bo4    = _fmt_b | _fmt_has_o | _fmt_has_u4;


  public static int specialLengthAt(Method method, int bci) {
    int code = codeAt(method, bci);
    switch (code) {
    case _wide:
      return wideLengthFor(method.getBytecodeOrBPAt(bci + 1));
    case _tableswitch:
      {
        int alignedBCI = Bits.roundTo(bci + 1, jintSize);
        int lo = method.getBytecodeIntArg(alignedBCI + 1*jintSize);
        int hi = method.getBytecodeIntArg(alignedBCI + 2*jintSize);
        return (alignedBCI - bci) + (3 + hi - lo + 1)*jintSize;
      }

    case _lookupswitch:      // fall through
    case _fast_binaryswitch: // fall through
    case _fast_linearswitch:
      {
        int alignedBCI = Bits.roundTo(bci + 1, jintSize);
        int npairs = method.getBytecodeIntArg(alignedBCI + jintSize);
        return (alignedBCI - bci) + (2 + 2*npairs)*jintSize;
      }

    }
    throw new RuntimeException("should not reach here");
  }

  // Conversion
  public static void check(int code) {
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(isDefined(code), "illegal code " + code);
    }
  }
  public static void wideCheck(int code) {
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(wideIsDefined(code), "illegal code " + code);
    }
  }

  /** Fetches a bytecode, hiding breakpoints as necessary */
  public static int codeAt(Method method, int bci) {
    int res = codeOrBPAt(method, bci);
    if (res == _breakpoint) {
      res = method.getOrigBytecodeAt(bci);
    }
    return res;
  }

  /** Fetches a bytecode or a breakpoint */
  public static int codeOrBPAt(Method method, int bci) {
    return method.getBytecodeOrBPAt(bci);
  }

  public static boolean isActiveBreakpointAt(Method method, int bci) {
    return (codeOrBPAt(method, bci) == _breakpoint);
  }

  // find a bytecode, behind a breakpoint if necessary:
  // FIXME: not yet implementable
  //   static Code       non_breakpoint_code_at(address bcp, Method* method = null);

  // Bytecode attributes
  public static boolean   isDefined    (int code) { return 0 <= code && code < number_of_codes && flags(code, false) != 0; }
  public static boolean   wideIsDefined(int code) { return isDefined(code) && flags(code, true) != 0; }
  public static String    name         (int code) { check(code);      return _name          [code]; }
  public static String    format       (int code) { check(code);      return _format        [code]; }
  public static String    wideFormat   (int code) { wideCheck(code);  return _wide_format   [code]; }
  public static int       resultType   (int code) { check(code);      return _result_type   [code]; }
  public static int       depth        (int code) { check(code);      return _depth         [code]; }
  public static int       lengthFor    (int code) { check(code);      return _lengths       [code] & 0xF; }
  public static int       wideLengthFor(int code) { check(code);      return _lengths       [code] >> 4; }
  public static boolean   canTrap      (int code) { check(code);      return has_all_flags(code, _bc_can_trap, false); }
  public static int       javaCode     (int code) { check(code);      return _java_code     [code]; }
  public static boolean   canRewrite   (int code) { check(code);      return has_all_flags(code, _bc_can_rewrite, false); }
  public static boolean   native_byte_order(int code)  { check(code);      return has_all_flags(code, _fmt_has_nbo, false); }
  public static boolean   uses_cp_cache  (int code)    { check(code);      return has_all_flags(code, _fmt_has_j, false); }
  public static int       lengthAt     (Method method, int bci) { int l = lengthFor(codeAt(method, bci)); return l > 0 ? l : specialLengthAt(method, bci); }
  public static int       javaLengthAt (Method method, int bci) { int l = lengthFor(javaCode(codeAt(method, bci))); return l > 0 ? l : specialLengthAt(method, bci); }
  public static boolean   isJavaCode   (int code) { return 0 <= code && code < number_of_java_codes; }
  public static boolean   isFastCode   (int code) { return number_of_java_codes <= code && code < number_of_codes; }

  public static boolean   isAload      (int code) { return (code == _aload  || code == _aload_0  || code == _aload_1
                                                                            || code == _aload_2  || code == _aload_3); }
  public static boolean   isAstore     (int code) { return (code == _astore || code == _astore_0 || code == _astore_1
                                                                            || code == _astore_2 || code == _astore_3); }

  public static boolean   isZeroConst  (int code) { return (code == _aconst_null || code == _iconst_0
                                                                                 || code == _fconst_0 || code == _dconst_0); }

  static int         flags          (int code, boolean is_wide) {
    assert code == (code & 0xff) : "must be a byte";
    return _flags[code + (is_wide ? 256 : 0)];
  }
  static int         format_bits    (int code, boolean is_wide) { return flags(code, is_wide) & _all_fmt_bits; }
  static boolean     has_all_flags  (int code, int test_flags, boolean is_wide) {
    return (flags(code, is_wide) & test_flags) == test_flags;
  }

  static char compute_flags(String format) {
    return compute_flags(format, 0);
  }
  static char compute_flags(String format, int more_flags) {
    if (format == null)  return 0;  // not even more_flags
    int flags = more_flags;
    int fp = 0;
    if (format.length() == 0) {
      flags |= _fmt_not_simple; // but variable
    } else {
      switch (format.charAt(fp)) {
      case 'b':
        flags |= _fmt_not_variable;  // but simple
        ++fp;  // skip 'b'
        break;
      case 'w':
        flags |= _fmt_not_variable | _fmt_not_simple;
        ++fp;  // skip 'w'
      assert(format.charAt(fp) == 'b') : "wide format must start with 'wb'";
        ++fp;  // skip 'b'
        break;
      }
    }

    boolean has_nbo = false, has_jbo = false;
    int has_size = 0;
    while (fp < format.length()) {
      int this_flag = 0;
      char fc = format.charAt(fp++);
      switch (fc) {
      case '_': continue;         // ignore these

      case 'j': this_flag = _fmt_has_j; has_jbo = true; break;
      case 'k': this_flag = _fmt_has_k; has_jbo = true; break;
      case 'i': this_flag = _fmt_has_i; has_jbo = true; break;
      case 'c': this_flag = _fmt_has_c; has_jbo = true; break;
      case 'o': this_flag = _fmt_has_o; has_jbo = true; break;

        // uppercase versions mark native byte order (from Rewriter)
        // actually, only the 'J' case happens currently
      case 'J': this_flag = _fmt_has_j; has_nbo = true; break;
      case 'K': this_flag = _fmt_has_k; has_nbo = true; break;
      case 'I': this_flag = _fmt_has_i; has_nbo = true; break;
      case 'C': this_flag = _fmt_has_c; has_nbo = true; break;
      case 'O': this_flag = _fmt_has_o; has_nbo = true; break;
      default:  assert false : "bad char in format";
      }

      flags |= this_flag;

      assert !(has_jbo && has_nbo) : "mixed byte orders in format";
      if (has_nbo)
        flags |= _fmt_has_nbo;

      int this_size = 1;
      if (fp < format.length() && format.charAt(fp) == fc) {
        // advance beyond run of the same characters
        this_size = 2;
        while (fp  + 1 < format.length() && format.charAt(++fp) == fc)  this_size++;
        switch (this_size) {
        case 2: flags |= _fmt_has_u2; break;
        case 4: flags |= _fmt_has_u4; break;
        default: assert false : "bad rep count in format";
        }
      }
      assert has_size == 0 ||                     // no field yet
        this_size == has_size ||             // same size
        this_size < has_size && fp == format.length() : // last field can be short
             "mixed field sizes in format";
      has_size = this_size;
    }

    assert flags == (char)flags : "change _format_flags";
    return (char)flags;
  }


  //----------------------------------------------------------------------
  // Internals only below this point
  //

  private static String[]    _name;
  private static String[]    _format;
  private static String[]    _wide_format;
  private static int[]       _result_type;
  private static byte[]      _depth;
  private static byte[]      _lengths;
  private static int[]       _java_code;
  private static char[]      _flags;

  static {
    _name           = new String [number_of_codes];
    _format         = new String [number_of_codes];
    _wide_format    = new String [number_of_codes];
    _result_type    = new int    [number_of_codes]; // See BasicType.java
    _depth          = new byte   [number_of_codes];
    _lengths        = new byte   [number_of_codes];
    _java_code      = new int    [number_of_codes];
    _flags          = new char[256 * 2]; // all second page for wide formats

    // In case we want to fetch this information from the VM in the
    // future
    VM.registerVMInitializedObserver(new Observer() {
        public void update(Observable o, Object data) {
          initialize();
        }
      });
  }

  private static final int jintSize    =   4;

  //  private static String[]    _name           = new String [number_of_codes];
  //  private static String[]    _format         = new String [number_of_codes];
  //  private static String[]    _wide_format    = new String [number_of_codes];
  //  private static int[]       _result_type    = new int    [number_of_codes]; // See BasicType.java
  //  private static byte[]      _depth          = new byte   [number_of_codes];
  //  private static byte[]      _length         = new byte   [number_of_codes];
  //  private static boolean[]   _can_trap       = new boolean[number_of_codes];
  //  private static int[]       _java_code      = new int    [number_of_codes];
  //  private static boolean[]   _can_rewrite    = new boolean[number_of_codes];

  // Initialization
  private static void initialize() {
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(number_of_codes <= 256, "too many bytecodes");
    }

    // Format strings interpretation:
    //
    // b: bytecode
    // c: signed constant, Java byte-ordering
    // i: unsigned index , Java byte-ordering
    // j: unsigned index , native byte-ordering
    // o: branch offset  , Java byte-ordering
    // _: unused/ignored
    // w: wide bytecode
    //
    // Note: Right now the format strings are used for 2 purposes:
    //       1. to specify the length of the bytecode
    //          (= number of characters in format string)
    //       2. to specify the bytecode attributes
    //
    //       The bytecode attributes are currently used only for bytecode tracing
    //       (see BytecodeTracer); thus if more specific format information is
    //       used, one would also have to adjust the bytecode tracer.
    //
    // Note: For bytecodes with variable length, the format string is the empty string.

    // Note 1: null for the format string means the bytecode doesn't exist
    //         in that form.
    //
    // Note 2: The result type is T_ILLEGAL for bytecodes where the top of stack
    //         type after execution is not only determined by the bytecode itself.

    //  Java bytecodes
    //  bytecode               bytecode name           format   wide f.   result tp                stk traps
    def(_nop                 , "nop"                 , "b"    , null    , BasicType.getTVoid()   ,  0, false);
    def(_aconst_null         , "aconst_null"         , "b"    , null    , BasicType.getTObject() ,  1, false);
    def(_iconst_m1           , "iconst_m1"           , "b"    , null    , BasicType.getTInt()    ,  1, false);
    def(_iconst_0            , "iconst_0"            , "b"    , null    , BasicType.getTInt()    ,  1, false);
    def(_iconst_1            , "iconst_1"            , "b"    , null    , BasicType.getTInt()    ,  1, false);
    def(_iconst_2            , "iconst_2"            , "b"    , null    , BasicType.getTInt()    ,  1, false);
    def(_iconst_3            , "iconst_3"            , "b"    , null    , BasicType.getTInt()    ,  1, false);
    def(_iconst_4            , "iconst_4"            , "b"    , null    , BasicType.getTInt()    ,  1, false);
    def(_iconst_5            , "iconst_5"            , "b"    , null    , BasicType.getTInt()    ,  1, false);
    def(_lconst_0            , "lconst_0"            , "b"    , null    , BasicType.getTLong()   ,  2, false);
    def(_lconst_1            , "lconst_1"            , "b"    , null    , BasicType.getTLong()   ,  2, false);
    def(_fconst_0            , "fconst_0"            , "b"    , null    , BasicType.getTFloat()  ,  1, false);
    def(_fconst_1            , "fconst_1"            , "b"    , null    , BasicType.getTFloat()  ,  1, false);
    def(_fconst_2            , "fconst_2"            , "b"    , null    , BasicType.getTFloat()  ,  1, false);
    def(_dconst_0            , "dconst_0"            , "b"    , null    , BasicType.getTDouble() ,  2, false);
    def(_dconst_1            , "dconst_1"            , "b"    , null    , BasicType.getTDouble() ,  2, false);
    def(_bipush              , "bipush"              , "bc"   , null    , BasicType.getTInt()    ,  1, false);
    def(_sipush              , "sipush"              , "bcc"  , null    , BasicType.getTInt()    ,  1, false);
    def(_ldc                 , "ldc"                 , "bk"   , null    , BasicType.getTIllegal(),  1, true );
    def(_ldc_w               , "ldc_w"               , "bkk"  , null    , BasicType.getTIllegal(),  1, true );
    def(_ldc2_w              , "ldc2_w"              , "bkk"  , null    , BasicType.getTIllegal(),  2, true );
    def(_iload               , "iload"               , "bi"   , "wbii"  , BasicType.getTInt()    ,  1, false);
    def(_lload               , "lload"               , "bi"   , "wbii"  , BasicType.getTLong()   ,  2, false);
    def(_fload               , "fload"               , "bi"   , "wbii"  , BasicType.getTFloat()  ,  1, false);
    def(_dload               , "dload"               , "bi"   , "wbii"  , BasicType.getTDouble() ,  2, false);
    def(_aload               , "aload"               , "bi"   , "wbii"  , BasicType.getTObject() ,  1, false);
    def(_iload_0             , "iload_0"             , "b"    , null    , BasicType.getTInt()    ,  1, false);
    def(_iload_1             , "iload_1"             , "b"    , null    , BasicType.getTInt()    ,  1, false);
    def(_iload_2             , "iload_2"             , "b"    , null    , BasicType.getTInt()    ,  1, false);
    def(_iload_3             , "iload_3"             , "b"    , null    , BasicType.getTInt()    ,  1, false);
    def(_lload_0             , "lload_0"             , "b"    , null    , BasicType.getTLong()   ,  2, false);
    def(_lload_1             , "lload_1"             , "b"    , null    , BasicType.getTLong()   ,  2, false);
    def(_lload_2             , "lload_2"             , "b"    , null    , BasicType.getTLong()   ,  2, false);
    def(_lload_3             , "lload_3"             , "b"    , null    , BasicType.getTLong()   ,  2, false);
    def(_fload_0             , "fload_0"             , "b"    , null    , BasicType.getTFloat()  ,  1, false);
    def(_fload_1             , "fload_1"             , "b"    , null    , BasicType.getTFloat()  ,  1, false);
    def(_fload_2             , "fload_2"             , "b"    , null    , BasicType.getTFloat()  ,  1, false);
    def(_fload_3             , "fload_3"             , "b"    , null    , BasicType.getTFloat()  ,  1, false);
    def(_dload_0             , "dload_0"             , "b"    , null    , BasicType.getTDouble() ,  2, false);
    def(_dload_1             , "dload_1"             , "b"    , null    , BasicType.getTDouble() ,  2, false);
    def(_dload_2             , "dload_2"             , "b"    , null    , BasicType.getTDouble() ,  2, false);
    def(_dload_3             , "dload_3"             , "b"    , null    , BasicType.getTDouble() ,  2, false);
    def(_aload_0             , "aload_0"             , "b"    , null    , BasicType.getTObject() ,  1, true ); // rewriting in interpreter
    def(_aload_1             , "aload_1"             , "b"    , null    , BasicType.getTObject() ,  1, false);
    def(_aload_2             , "aload_2"             , "b"    , null    , BasicType.getTObject() ,  1, false);
    def(_aload_3             , "aload_3"             , "b"    , null    , BasicType.getTObject() ,  1, false);
    def(_iaload              , "iaload"              , "b"    , null    , BasicType.getTInt()    , -1, true );
    def(_laload              , "laload"              , "b"    , null    , BasicType.getTLong()   ,  0, true );
    def(_faload              , "faload"              , "b"    , null    , BasicType.getTFloat()  , -1, true );
    def(_daload              , "daload"              , "b"    , null    , BasicType.getTDouble() ,  0, true );
    def(_aaload              , "aaload"              , "b"    , null    , BasicType.getTObject() , -1, true );
    def(_baload              , "baload"              , "b"    , null    , BasicType.getTInt()    , -1, true );
    def(_caload              , "caload"              , "b"    , null    , BasicType.getTInt()    , -1, true );
    def(_saload              , "saload"              , "b"    , null    , BasicType.getTInt()    , -1, true );
    def(_istore              , "istore"              , "bi"   , "wbii"  , BasicType.getTVoid()   , -1, false);
    def(_lstore              , "lstore"              , "bi"   , "wbii"  , BasicType.getTVoid()   , -2, false);
    def(_fstore              , "fstore"              , "bi"   , "wbii"  , BasicType.getTVoid()   , -1, false);
    def(_dstore              , "dstore"              , "bi"   , "wbii"  , BasicType.getTVoid()   , -2, false);
    def(_astore              , "astore"              , "bi"   , "wbii"  , BasicType.getTVoid()   , -1, false);
    def(_istore_0            , "istore_0"            , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_istore_1            , "istore_1"            , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_istore_2            , "istore_2"            , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_istore_3            , "istore_3"            , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_lstore_0            , "lstore_0"            , "b"    , null    , BasicType.getTVoid()   , -2, false);
    def(_lstore_1            , "lstore_1"            , "b"    , null    , BasicType.getTVoid()   , -2, false);
    def(_lstore_2            , "lstore_2"            , "b"    , null    , BasicType.getTVoid()   , -2, false);
    def(_lstore_3            , "lstore_3"            , "b"    , null    , BasicType.getTVoid()   , -2, false);
    def(_fstore_0            , "fstore_0"            , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_fstore_1            , "fstore_1"            , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_fstore_2            , "fstore_2"            , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_fstore_3            , "fstore_3"            , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_dstore_0            , "dstore_0"            , "b"    , null    , BasicType.getTVoid()   , -2, false);
    def(_dstore_1            , "dstore_1"            , "b"    , null    , BasicType.getTVoid()   , -2, false);
    def(_dstore_2            , "dstore_2"            , "b"    , null    , BasicType.getTVoid()   , -2, false);
    def(_dstore_3            , "dstore_3"            , "b"    , null    , BasicType.getTVoid()   , -2, false);
    def(_astore_0            , "astore_0"            , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_astore_1            , "astore_1"            , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_astore_2            , "astore_2"            , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_astore_3            , "astore_3"            , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_iastore             , "iastore"             , "b"    , null    , BasicType.getTVoid()   , -3, true );
    def(_lastore             , "lastore"             , "b"    , null    , BasicType.getTVoid()   , -4, true );
    def(_fastore             , "fastore"             , "b"    , null    , BasicType.getTVoid()   , -3, true );
    def(_dastore             , "dastore"             , "b"    , null    , BasicType.getTVoid()   , -4, true );
    def(_aastore             , "aastore"             , "b"    , null    , BasicType.getTVoid()   , -3, true );
    def(_bastore             , "bastore"             , "b"    , null    , BasicType.getTVoid()   , -3, true );
    def(_castore             , "castore"             , "b"    , null    , BasicType.getTVoid()   , -3, true );
    def(_sastore             , "sastore"             , "b"    , null    , BasicType.getTVoid()   , -3, true );
    def(_pop                 , "pop"                 , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_pop2                , "pop2"                , "b"    , null    , BasicType.getTVoid()   , -2, false);
    def(_dup                 , "dup"                 , "b"    , null    , BasicType.getTVoid()   ,  1, false);
    def(_dup_x1              , "dup_x1"              , "b"    , null    , BasicType.getTVoid()   ,  1, false);
    def(_dup_x2              , "dup_x2"              , "b"    , null    , BasicType.getTVoid()   ,  1, false);
    def(_dup2                , "dup2"                , "b"    , null    , BasicType.getTVoid()   ,  2, false);
    def(_dup2_x1             , "dup2_x1"             , "b"    , null    , BasicType.getTVoid()   ,  2, false);
    def(_dup2_x2             , "dup2_x2"             , "b"    , null    , BasicType.getTVoid()   ,  2, false);
    def(_swap                , "swap"                , "b"    , null    , BasicType.getTVoid()   ,  0, false);
    def(_iadd                , "iadd"                , "b"    , null    , BasicType.getTInt()    , -1, false);
    def(_ladd                , "ladd"                , "b"    , null    , BasicType.getTLong()   , -2, false);
    def(_fadd                , "fadd"                , "b"    , null    , BasicType.getTFloat()  , -1, false);
    def(_dadd                , "dadd"                , "b"    , null    , BasicType.getTDouble() , -2, false);
    def(_isub                , "isub"                , "b"    , null    , BasicType.getTInt()    , -1, false);
    def(_lsub                , "lsub"                , "b"    , null    , BasicType.getTLong()   , -2, false);
    def(_fsub                , "fsub"                , "b"    , null    , BasicType.getTFloat()  , -1, false);
    def(_dsub                , "dsub"                , "b"    , null    , BasicType.getTDouble() , -2, false);
    def(_imul                , "imul"                , "b"    , null    , BasicType.getTInt()    , -1, false);
    def(_lmul                , "lmul"                , "b"    , null    , BasicType.getTLong()   , -2, false);
    def(_fmul                , "fmul"                , "b"    , null    , BasicType.getTFloat()  , -1, false);
    def(_dmul                , "dmul"                , "b"    , null    , BasicType.getTDouble() , -2, false);
    def(_idiv                , "idiv"                , "b"    , null    , BasicType.getTInt()    , -1, true );
    def(_ldiv                , "ldiv"                , "b"    , null    , BasicType.getTLong()   , -2, true );
    def(_fdiv                , "fdiv"                , "b"    , null    , BasicType.getTFloat()  , -1, false);
    def(_ddiv                , "ddiv"                , "b"    , null    , BasicType.getTDouble() , -2, false);
    def(_irem                , "irem"                , "b"    , null    , BasicType.getTInt()    , -1, true );
    def(_lrem                , "lrem"                , "b"    , null    , BasicType.getTLong()   , -2, true );
    def(_frem                , "frem"                , "b"    , null    , BasicType.getTFloat()  , -1, false);
    def(_drem                , "drem"                , "b"    , null    , BasicType.getTDouble() , -2, false);
    def(_ineg                , "ineg"                , "b"    , null    , BasicType.getTInt()    ,  0, false);
    def(_lneg                , "lneg"                , "b"    , null    , BasicType.getTLong()   ,  0, false);
    def(_fneg                , "fneg"                , "b"    , null    , BasicType.getTFloat()  ,  0, false);
    def(_dneg                , "dneg"                , "b"    , null    , BasicType.getTDouble() ,  0, false);
    def(_ishl                , "ishl"                , "b"    , null    , BasicType.getTInt()    , -1, false);
    def(_lshl                , "lshl"                , "b"    , null    , BasicType.getTLong()   , -1, false);
    def(_ishr                , "ishr"                , "b"    , null    , BasicType.getTInt()    , -1, false);
    def(_lshr                , "lshr"                , "b"    , null    , BasicType.getTLong()   , -1, false);
    def(_iushr               , "iushr"               , "b"    , null    , BasicType.getTInt()    , -1, false);
    def(_lushr               , "lushr"               , "b"    , null    , BasicType.getTLong()   , -1, false);
    def(_iand                , "iand"                , "b"    , null    , BasicType.getTInt()    , -1, false);
    def(_land                , "land"                , "b"    , null    , BasicType.getTLong()   , -2, false);
    def(_ior                 , "ior"                 , "b"    , null    , BasicType.getTInt()    , -1, false);
    def(_lor                 , "lor"                 , "b"    , null    , BasicType.getTLong()   , -2, false);
    def(_ixor                , "ixor"                , "b"    , null    , BasicType.getTInt()    , -1, false);
    def(_lxor                , "lxor"                , "b"    , null    , BasicType.getTLong()   , -2, false);
    def(_iinc                , "iinc"                , "bic"  , "wbiicc", BasicType.getTVoid()   ,  0, false);
    def(_i2l                 , "i2l"                 , "b"    , null    , BasicType.getTLong()   ,  1, false);
    def(_i2f                 , "i2f"                 , "b"    , null    , BasicType.getTFloat()  ,  0, false);
    def(_i2d                 , "i2d"                 , "b"    , null    , BasicType.getTDouble() ,  1, false);
    def(_l2i                 , "l2i"                 , "b"    , null    , BasicType.getTInt()    , -1, false);
    def(_l2f                 , "l2f"                 , "b"    , null    , BasicType.getTFloat()  , -1, false);
    def(_l2d                 , "l2d"                 , "b"    , null    , BasicType.getTDouble() ,  0, false);
    def(_f2i                 , "f2i"                 , "b"    , null    , BasicType.getTInt()    ,  0, false);
    def(_f2l                 , "f2l"                 , "b"    , null    , BasicType.getTLong()   ,  1, false);
    def(_f2d                 , "f2d"                 , "b"    , null    , BasicType.getTDouble() ,  1, false);
    def(_d2i                 , "d2i"                 , "b"    , null    , BasicType.getTInt()    , -1, false);
    def(_d2l                 , "d2l"                 , "b"    , null    , BasicType.getTLong()   ,  0, false);
    def(_d2f                 , "d2f"                 , "b"    , null    , BasicType.getTFloat()  , -1, false);
    def(_i2b                 , "i2b"                 , "b"    , null    , BasicType.getTByte()   ,  0, false);
    def(_i2c                 , "i2c"                 , "b"    , null    , BasicType.getTChar()   ,  0, false);
    def(_i2s                 , "i2s"                 , "b"    , null    , BasicType.getTShort()  ,  0, false);
    def(_lcmp                , "lcmp"                , "b"    , null    , BasicType.getTVoid()   , -3, false);
    def(_fcmpl               , "fcmpl"               , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_fcmpg               , "fcmpg"               , "b"    , null    , BasicType.getTVoid()   , -1, false);
    def(_dcmpl               , "dcmpl"               , "b"    , null    , BasicType.getTVoid()   , -3, false);
    def(_dcmpg               , "dcmpg"               , "b"    , null    , BasicType.getTVoid()   , -3, false);
    def(_ifeq                , "ifeq"                , "boo"  , null    , BasicType.getTVoid()   , -1, false);
    def(_ifne                , "ifne"                , "boo"  , null    , BasicType.getTVoid()   , -1, false);
    def(_iflt                , "iflt"                , "boo"  , null    , BasicType.getTVoid()   , -1, false);
    def(_ifge                , "ifge"                , "boo"  , null    , BasicType.getTVoid()   , -1, false);
    def(_ifgt                , "ifgt"                , "boo"  , null    , BasicType.getTVoid()   , -1, false);
    def(_ifle                , "ifle"                , "boo"  , null    , BasicType.getTVoid()   , -1, false);
    def(_if_icmpeq           , "if_icmpeq"           , "boo"  , null    , BasicType.getTVoid()   , -2, false);
    def(_if_icmpne           , "if_icmpne"           , "boo"  , null    , BasicType.getTVoid()   , -2, false);
    def(_if_icmplt           , "if_icmplt"           , "boo"  , null    , BasicType.getTVoid()   , -2, false);
    def(_if_icmpge           , "if_icmpge"           , "boo"  , null    , BasicType.getTVoid()   , -2, false);
    def(_if_icmpgt           , "if_icmpgt"           , "boo"  , null    , BasicType.getTVoid()   , -2, false);
    def(_if_icmple           , "if_icmple"           , "boo"  , null    , BasicType.getTVoid()   , -2, false);
    def(_if_acmpeq           , "if_acmpeq"           , "boo"  , null    , BasicType.getTVoid()   , -2, false);
    def(_if_acmpne           , "if_acmpne"           , "boo"  , null    , BasicType.getTVoid()   , -2, false);
    def(_goto                , "goto"                , "boo"  , null    , BasicType.getTVoid()   ,  0, false);
    def(_jsr                 , "jsr"                 , "boo"  , null    , BasicType.getTInt()    ,  0, false);
    def(_ret                 , "ret"                 , "bi"   , "wbii"  , BasicType.getTVoid()   ,  0, false);
    def(_tableswitch         , "tableswitch"         , ""     , null    , BasicType.getTVoid()   , -1, false); // may have backward branches
    def(_lookupswitch        , "lookupswitch"        , ""     , null    , BasicType.getTVoid()   , -1, false); // rewriting in interpreter
    def(_ireturn             , "ireturn"             , "b"    , null    , BasicType.getTInt()    , -1, true );
    def(_lreturn             , "lreturn"             , "b"    , null    , BasicType.getTLong()   , -2, true );
    def(_freturn             , "freturn"             , "b"    , null    , BasicType.getTFloat()  , -1, true );
    def(_dreturn             , "dreturn"             , "b"    , null    , BasicType.getTDouble() , -2, true );
    def(_areturn             , "areturn"             , "b"    , null    , BasicType.getTObject() , -1, true );
    def(_return              , "return"              , "b"    , null    , BasicType.getTVoid()   ,  0, true );
    def(_getstatic           , "getstatic"           , "bJJ"  , null    , BasicType.getTIllegal(),  1, true );
    def(_putstatic           , "putstatic"           , "bJJ"  , null    , BasicType.getTIllegal(), -1, true );
    def(_getfield            , "getfield"            , "bJJ"  , null    , BasicType.getTIllegal(),  0, true );
    def(_putfield            , "putfield"            , "bJJ"  , null    , BasicType.getTIllegal(), -2, true );
    def(_invokevirtual       , "invokevirtual"       , "bJJ"  , null    , BasicType.getTIllegal(), -1, true );
    def(_invokespecial       , "invokespecial"       , "bJJ"  , null    , BasicType.getTIllegal(), -1, true );
    def(_invokestatic        , "invokestatic"        , "bJJ"  , null    , BasicType.getTIllegal(),  0, true );
    def(_invokeinterface     , "invokeinterface"     , "bJJ__", null    , BasicType.getTIllegal(), -1, true );
    def(_invokedynamic       , "invokedynamic"       , "bJJJJ", null    , BasicType.getTIllegal(),  0, true );
    def(_new                 , "new"                 , "bkk"  , null    , BasicType.getTObject() ,  1, true );
    def(_newarray            , "newarray"            , "bc"   , null    , BasicType.getTObject() ,  0, true );
    def(_anewarray           , "anewarray"           , "bkk"  , null    , BasicType.getTObject() ,  0, true );
    def(_arraylength         , "arraylength"         , "b"    , null    , BasicType.getTVoid()   ,  0, true );
    def(_athrow              , "athrow"              , "b"    , null    , BasicType.getTVoid()   , -1, true );
    def(_checkcast           , "checkcast"           , "bkk"  , null    , BasicType.getTObject() ,  0, true );
    def(_instanceof          , "instanceof"          , "bkk"  , null    , BasicType.getTInt()    ,  0, true );
    def(_monitorenter        , "monitorenter"        , "b"    , null    , BasicType.getTVoid()   , -1, true );
    def(_monitorexit         , "monitorexit"         , "b"    , null    , BasicType.getTVoid()   , -1, true );
    def(_wide                , "wide"                , ""     , null    , BasicType.getTVoid()   ,  0, false);
    def(_multianewarray      , "multianewarray"      , "bkkc" , null    , BasicType.getTObject() ,  1, true );
    def(_ifnull              , "ifnull"              , "boo"  , null    , BasicType.getTVoid()   , -1, false);
    def(_ifnonnull           , "ifnonnull"           , "boo"  , null    , BasicType.getTVoid()   , -1, false);
    def(_goto_w              , "goto_w"              , "boooo", null    , BasicType.getTVoid()   ,  0, false);
    def(_jsr_w               , "jsr_w"               , "boooo", null    , BasicType.getTInt()    ,  0, false);
    def(_breakpoint          , "breakpoint"          , ""     , null    , BasicType.getTVoid()   ,  0, true );

    //  JVM bytecodes
    //  bytecode               bytecode name           format   wide f.   result tp               stk traps  std code

    def(_fast_agetfield      , "fast_agetfield"      , "bJJ"  , null    , BasicType.getTObject() ,  0, true , _getfield       );
    def(_fast_bgetfield      , "fast_bgetfield"      , "bJJ"  , null    , BasicType.getTInt()    ,  0, true , _getfield       );
    def(_fast_cgetfield      , "fast_cgetfield"      , "bJJ"  , null    , BasicType.getTChar()   ,  0, true , _getfield       );
    def(_fast_dgetfield      , "fast_dgetfield"      , "bJJ"  , null    , BasicType.getTDouble() ,  0, true , _getfield       );
    def(_fast_fgetfield      , "fast_fgetfield"      , "bJJ"  , null    , BasicType.getTFloat()  ,  0, true , _getfield       );
    def(_fast_igetfield      , "fast_igetfield"      , "bJJ"  , null    , BasicType.getTInt()    ,  0, true , _getfield       );
    def(_fast_lgetfield      , "fast_lgetfield"      , "bJJ"  , null    , BasicType.getTLong()   ,  0, true , _getfield       );
    def(_fast_sgetfield      , "fast_sgetfield"      , "bJJ"  , null    , BasicType.getTShort()  ,  0, true , _getfield       );

    def(_fast_aputfield      , "fast_aputfield"      , "bJJ"  , null    , BasicType.getTObject() ,  0, true , _putfield       );
    def(_fast_bputfield      , "fast_bputfield"      , "bJJ"  , null    , BasicType.getTInt()    ,  0, true , _putfield       );
    def(_fast_cputfield      , "fast_cputfield"      , "bJJ"  , null    , BasicType.getTChar()   ,  0, true , _putfield       );
    def(_fast_dputfield      , "fast_dputfield"      , "bJJ"  , null    , BasicType.getTDouble() ,  0, true , _putfield       );
    def(_fast_fputfield      , "fast_fputfield"      , "bJJ"  , null    , BasicType.getTFloat()  ,  0, true , _putfield       );
    def(_fast_iputfield      , "fast_iputfield"      , "bJJ"  , null    , BasicType.getTInt()    ,  0, true , _putfield       );
    def(_fast_lputfield      , "fast_lputfield"      , "bJJ"  , null    , BasicType.getTLong()   ,  0, true , _putfield       );
    def(_fast_sputfield      , "fast_sputfield"      , "bJJ"  , null    , BasicType.getTShort()  ,  0, true , _putfield       );

    def(_fast_aload_0        , "fast_aload_0"        , "b"    , null    , BasicType.getTObject() ,  1, true , _aload_0        );
    def(_fast_iaccess_0      , "fast_iaccess_0"      , "b_JJ" , null    , BasicType.getTInt()    ,  1, true , _aload_0        );
    def(_fast_aaccess_0      , "fast_aaccess_0"      , "b_JJ" , null    , BasicType.getTObject() ,  1, true , _aload_0        );
    def(_fast_faccess_0      , "fast_faccess_0"      , "b_JJ" , null    , BasicType.getTObject() ,  1, true , _aload_0        );

    def(_fast_iload          , "fast_iload"          , "bi"   , null    , BasicType.getTInt()    ,  1, false, _iload          );
    def(_fast_iload2         , "fast_iload2"         , "bi_i" , null    , BasicType.getTInt()    ,  2, false, _iload          );
    def(_fast_icaload        , "fast_icaload"        , "bi_"  , null    , BasicType.getTInt()    ,  0, false, _iload          );

    // Faster method invocation.
    def(_fast_invokevfinal   , "fast_invokevfinal"   , "bJJ"  , null    , BasicType.getTIllegal(), -1, true, _invokevirtual   );

    def(_fast_linearswitch   , "fast_linearswitch"   , ""     , null    , BasicType.getTVoid()   , -1, false, _lookupswitch   );
    def(_fast_binaryswitch   , "fast_binaryswitch"   , ""     , null    , BasicType.getTVoid()   , -1, false, _lookupswitch   );
    def(_fast_aldc           , "fast_aldc"           , "bj"   , null    , BasicType.getTObject(),   1, true,  _ldc            );
    def(_fast_aldc_w         , "fast_aldc_w"         , "bJJ"  , null    , BasicType.getTObject(),   1, true,  _ldc_w          );

    def(_return_register_finalizer, "return_register_finalizer", "b"    , null    , BasicType.getTVoid()   , 0, true, _return );

    // special handling of signature-polymorphic methods
    def(_invokehandle        , "invokehandle"        , "bJJ"  , null    , BasicType.getTIllegal(), -1, true, _invokevirtual   );

    def(_shouldnotreachhere  , "_shouldnotreachhere" , "b"    , null    , BasicType.getTVoid()   ,  0, false);

    if (Assert.ASSERTS_ENABLED) {
      // compare can_trap information for each bytecode with the
      // can_trap information for the corresponding base bytecode
      // (if a rewritten bytecode can trap, so must the base bytecode)
      for (int i = 0; i < number_of_codes; i++) {
        if (isDefined(i)) {
          int j = javaCode(i);
          if (canTrap(i) && !canTrap(j)) {
            Assert.that(false, name(i) + " can trap => " + name(j) + " can trap, too");
          }
        }
      }
    }
  }

  private static void def(int code, String name, String format, String wide_format, int result_type, int depth, boolean can_trap) {
    def(code, name, format, wide_format, result_type, depth, can_trap, code);
  }

  private static void def(int code, String name, String format, String wide_format, int result_type, int depth, boolean can_trap, int java_code) {
    if (Assert.ASSERTS_ENABLED) {
      Assert.that(wide_format == null || format != null, "short form must exist if there's a wide form");
    }
    int len  = (format      != null ? format.length()      : 0);
    int wlen = (wide_format != null ? wide_format.length() : 0);
    _name          [code] = name;
    _result_type   [code] = result_type;
    _depth         [code] = (byte) depth;
    _lengths       [code] = (byte)((wlen << 4) | (len & 0xF));
    _java_code     [code] = java_code;
    _format        [code] = format;
    _wide_format   [code] = wide_format;
    int bc_flags = 0;
    if (can_trap)           bc_flags |= _bc_can_trap;
    if (java_code != code)  bc_flags |= _bc_can_rewrite;
    _flags[code+0*256] = compute_flags(format,      bc_flags);
    _flags[code+1*256] = compute_flags(wide_format, bc_flags);
  }
}

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