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1 /*
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2 * Copyright 1998-2005 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 HandlerTableEntry describes an individual entry of a subtable
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26 // of ExceptionHandlerTable. An entry consists of a pair(bci, pco),
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27 // where bci is the exception handler bci, and pco is the pc offset
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28 // relative to the nmethod code start for the compiled exception
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29 // handler corresponding to the (interpreted) exception handler
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30 // starting at bci.
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31 //
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32 // The first HandlerTableEntry of each subtable holds the length
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33 // and catch_pco for the subtable (the length is the number of
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34 // subtable entries w/o header).
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35
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36 class HandlerTableEntry {
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37 private:
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38 int _bci;
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39 int _pco;
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40 int _scope_depth;
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41
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42 public:
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43 HandlerTableEntry(int bci, int pco, int scope_depth) {
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44 assert( 0 <= pco, "pco must be positive");
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45 assert( 0 <= scope_depth, "scope_depth must be positive");
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46 _bci = bci;
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47 _pco = pco;
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48 _scope_depth = scope_depth;
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49 }
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50
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51 int len() const { return _bci; } // for entry at subtable begin
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52 int bci() const { return _bci; }
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53 int pco() const { return _pco; }
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54 int scope_depth() const { return _scope_depth; }
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55 };
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56
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57
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58 // An ExceptionHandlerTable is an abstraction over a list of subtables
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59 // of exception handlers for CatchNodes. Each subtable has a one-entry
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60 // header holding length and catch_pco of the subtable, followed
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61 // by 'length' entries for each exception handler that can be reached
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62 // from the corresponding CatchNode. The catch_pco is the pc offset of
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63 // the CatchNode in the corresponding nmethod. Empty subtables are dis-
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64 // carded.
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65 //
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66 // Structure of the table:
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67 //
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68 // table = { subtable }.
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69 // subtable = header entry { entry }.
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70 // header = a pair (number of subtable entries, catch pc offset, [unused])
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71 // entry = a pair (handler bci, handler pc offset, scope depth)
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72 //
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73 // An ExceptionHandlerTable can be created from scratch, in which case
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74 // it is possible to add subtables. It can also be created from an
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75 // nmethod (for lookup purposes) in which case the table cannot be
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76 // modified.
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77
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78 class nmethod;
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79 class ExceptionHandlerTable VALUE_OBJ_CLASS_SPEC {
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80 private:
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81 HandlerTableEntry* _table; // the table
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82 int _length; // the current length of the table
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83 int _size; // the number of allocated entries
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84 ReallocMark _nesting; // assertion check for reallocations
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85
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86 // add the entry & grow the table if needed
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87 void add_entry(HandlerTableEntry entry);
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88 HandlerTableEntry* subtable_for(int catch_pco) const;
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89
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90 public:
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91 // (compile-time) construction within compiler
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92 ExceptionHandlerTable(int initial_size = 8);
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93
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94 // (run-time) construction from nmethod
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95 ExceptionHandlerTable(const nmethod* nm);
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96
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97 // (compile-time) add entries
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98 void add_subtable(
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99 int catch_pco, // the pc offset for the CatchNode
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100 GrowableArray<intptr_t>* handler_bcis, // the exception handler entry point bcis
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101 GrowableArray<intptr_t>* scope_depths_from_top_scope,
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102 // if representing exception handlers in multiple
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103 // inlined scopes, indicates which scope relative to
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104 // the youngest/innermost one in which we are performing
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105 // the lookup; zero (or null GrowableArray) indicates
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106 // innermost scope
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107 GrowableArray<intptr_t>* handler_pcos // pc offsets for the compiled handlers
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108 );
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109
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110 // nmethod support
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111 int size_in_bytes() const { return round_to(_length * sizeof(HandlerTableEntry), oopSize); }
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112 void copy_to(nmethod* nm);
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113
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114 // lookup
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115 HandlerTableEntry* entry_for(int catch_pco, int handler_bci, int scope_depth) const;
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116
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117 // debugging
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118 void print_subtable(HandlerTableEntry* t) const;
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119 void print() const;
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120 void print_subtable_for(int catch_pco) const;
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121 };
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122
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123
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124 // ----------------------------------------------------------------------------
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125 // Implicit null exception tables. Maps an exception PC offset to a
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126 // continuation PC offset. During construction it's a variable sized
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127 // array with a max size and current length. When stored inside an
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128 // nmethod a zero length table takes no space. This is detected by
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129 // nul_chk_table_size() == 0. Otherwise the table has a length word
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130 // followed by pairs of <excp-offset, const-offset>.
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131
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132 // Use 32-bit representation for offsets
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133 typedef uint implicit_null_entry;
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134
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135 class ImplicitExceptionTable VALUE_OBJ_CLASS_SPEC {
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136 uint _size;
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137 uint _len;
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138 implicit_null_entry *_data;
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139 implicit_null_entry *adr( uint idx ) const { return &_data[2*idx]; }
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140 ReallocMark _nesting; // assertion check for reallocations
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141 public:
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142 ImplicitExceptionTable( ) : _data(0), _size(0), _len(0) { }
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143 // (run-time) construction from nmethod
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144 ImplicitExceptionTable( const nmethod *nm );
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145
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146 void set_size( uint size );
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147 void append( uint exec_off, uint cont_off );
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148 uint at( uint exec_off ) const;
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149
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150 uint len() const { return _len; }
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151 int size_in_bytes() const { return len() == 0 ? 0 : ((2 * len() + 1) * sizeof(implicit_null_entry)); }
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152
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153 void copy_to(nmethod* nm);
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154 void print(address base) const;
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155 void verify(nmethod *nm) const;
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156 };
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