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1 /*
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2 * Copyright 1997-2005 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 // A BytecodeStream is used for fast iteration over the bytecodes
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26 // of a methodOop.
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27 //
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28 // Usage:
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29 //
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30 // BytecodeStream s(method);
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31 // Bytecodes::Code c;
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32 // while ((c = s.next()) >= 0) {
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33 // ...
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34 // }
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35 //
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36 // A RawBytecodeStream is a simple version of BytecodeStream.
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37 // It is used ONLY when we know the bytecodes haven't been rewritten
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38 // yet, such as in the rewriter or the verifier. Currently only the
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39 // verifier uses this class.
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40
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41 class RawBytecodeStream: StackObj {
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42 protected:
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43 // stream buffer
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44 methodHandle _method; // read from method directly
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45
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46 // reading position
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47 int _bci; // bci if current bytecode
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48 int _next_bci; // bci of next bytecode
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49 int _end_bci; // bci after the current iteration interval
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50
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51 // last bytecode read
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52 Bytecodes::Code _code;
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53 bool _is_wide;
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54
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55 public:
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56 // Construction
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57 RawBytecodeStream(methodHandle method) : _method(method) {
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58 set_interval(0, _method->code_size());
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59 }
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60
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61 // Iteration control
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62 void set_interval(int beg_bci, int end_bci) {
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63 // iterate over the interval [beg_bci, end_bci)
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64 assert(0 <= beg_bci && beg_bci <= method()->code_size(), "illegal beg_bci");
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65 assert(0 <= end_bci && end_bci <= method()->code_size(), "illegal end_bci");
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66 // setup of iteration pointers
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67 _bci = beg_bci;
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68 _next_bci = beg_bci;
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69 _end_bci = end_bci;
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70 }
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71 void set_start (int beg_bci) {
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72 set_interval(beg_bci, _method->code_size());
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73 }
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74
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75 // Iteration
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76 // Use raw_next() rather than next() for faster method reference
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77 Bytecodes::Code raw_next() {
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78 Bytecodes::Code code;
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79 // set reading position
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80 _bci = _next_bci;
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81 assert(!is_last_bytecode(), "caller should check is_last_bytecode()");
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82
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83 address bcp = RawBytecodeStream::bcp();
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84 code = Bytecodes::code_or_bp_at(bcp);
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85
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86 // set next bytecode position
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87 int l = Bytecodes::length_for(code);
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88 if (l > 0 && (_bci + l) <= _end_bci) {
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89 assert(code != Bytecodes::_wide && code != Bytecodes::_tableswitch
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90 && code != Bytecodes::_lookupswitch, "can't be special bytecode");
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91 _is_wide = false;
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92 _next_bci += l;
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93 _code = code;
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94 return code;
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95 } else if (code == Bytecodes::_wide && _bci + 1 >= _end_bci) {
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96 return Bytecodes::_illegal;
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97 } else {
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98 return raw_next_special(code);
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99 }
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100 }
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101 Bytecodes::Code raw_next_special(Bytecodes::Code code);
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102
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103 // Stream attributes
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104 methodHandle method() const { return _method; }
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105
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106 int bci() const { return _bci; }
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107 int next_bci() const { return _next_bci; }
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108 int end_bci() const { return _end_bci; }
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109
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110 Bytecodes::Code code() const { return _code; }
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111 bool is_wide() const { return _is_wide; }
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112 bool is_last_bytecode() const { return _next_bci >= _end_bci; }
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113
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114 address bcp() const { return method()->code_base() + _bci; }
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115 address next_bcp() { return method()->code_base() + _next_bci; }
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116
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117 // State changes
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118 void set_next_bci(int bci) { assert(0 <= bci && bci <= method()->code_size(), "illegal bci"); _next_bci = bci; }
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119
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120 // Bytecode-specific attributes
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121 int dest() const { return bci() + (short)Bytes::get_Java_u2(bcp() + 1); }
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122 int dest_w() const { return bci() + (int )Bytes::get_Java_u4(bcp() + 1); }
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123
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124 // Unsigned indices, widening
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125 int get_index() const { return (is_wide()) ? Bytes::get_Java_u2(bcp() + 2) : bcp()[1]; }
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126 int get_index_big() const { return (int)Bytes::get_Java_u2(bcp() + 1); }
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127 };
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128
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129 // In BytecodeStream, non-java bytecodes will be translated into the
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130 // corresponding java bytecodes.
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131
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132 class BytecodeStream: public RawBytecodeStream {
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133 public:
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134 // Construction
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135 BytecodeStream(methodHandle method) : RawBytecodeStream(method) { }
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136
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137 // Iteration
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138 Bytecodes::Code next() {
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139 Bytecodes::Code code;
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140 // set reading position
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141 _bci = _next_bci;
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142 if (is_last_bytecode()) {
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143 // indicate end of bytecode stream
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144 code = Bytecodes::_illegal;
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145 } else {
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146 // get bytecode
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147 address bcp = BytecodeStream::bcp();
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148 code = Bytecodes::java_code_at(bcp);
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149 // set next bytecode position
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150 //
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151 // note that we cannot advance before having the
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152 // tty bytecode otherwise the stepping is wrong!
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153 // (carefull: length_for(...) must be used first!)
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154 int l = Bytecodes::length_for(code);
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155 if (l == 0) l = Bytecodes::length_at(bcp);
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156 _next_bci += l;
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157 assert(_bci < _next_bci, "length must be > 0");
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158 // set attributes
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159 _is_wide = false;
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160 // check for special (uncommon) cases
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161 if (code == Bytecodes::_wide) {
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162 code = (Bytecodes::Code)bcp[1];
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163 _is_wide = true;
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164 }
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165 assert(Bytecodes::is_java_code(code), "sanity check");
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166 }
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167 _code = code;
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168 return _code;
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169 }
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170
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171 bool is_active_breakpoint() const { return Bytecodes::is_active_breakpoint_at(bcp()); }
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172 };
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