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111
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1 /* Exception handling and frame unwind runtime interface routines. -*- C -*-
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2 Copyright (C) 2001-2017 Free Software Foundation, Inc.
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3
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4 This file is part of GCC.
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5
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6 GCC is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 3, or (at your option)
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9 any later version.
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10
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11 GCC is distributed in the hope that it will be useful, but WITHOUT
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12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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14 License for more details.
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15
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16 Under Section 7 of GPL version 3, you are granted additional
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17 permissions described in the GCC Runtime Library Exception, version
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18 3.1, as published by the Free Software Foundation.
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19
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20 You should have received a copy of the GNU General Public License and
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21 a copy of the GCC Runtime Library Exception along with this program;
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22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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23 <http://www.gnu.org/licenses/>. */
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24
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25 /* This is derived from the C++ ABI for IA-64. Where we diverge
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26 for cross-architecture compatibility are noted with "@@@".
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27 This file is included from unwind-dw2.c, unwind-sjlj.c or
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28 unwind-ia64.c. */
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29
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30 /* Subroutine of _Unwind_RaiseException also invoked from _Unwind_Resume.
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31
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32 Unwind the stack calling the personality routine to find both the
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33 exception handler and intermediary cleanup code. We'll only locate
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34 the first such frame here. Cleanup code will call back into
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35 _Unwind_Resume and we'll continue Phase 2 there. */
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36
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37 static _Unwind_Reason_Code
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38 _Unwind_RaiseException_Phase2(struct _Unwind_Exception *exc,
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39 struct _Unwind_Context *context)
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40 {
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41 _Unwind_Reason_Code code;
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42
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43 while (1)
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44 {
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45 _Unwind_FrameState fs;
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46 int match_handler;
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47
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48 code = uw_frame_state_for (context, &fs);
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49
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50 /* Identify when we've reached the designated handler context. */
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51 match_handler = (uw_identify_context (context) == exc->private_2
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52 ? _UA_HANDLER_FRAME : 0);
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53
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54 if (code != _URC_NO_REASON)
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55 /* Some error encountered. Usually the unwinder doesn't
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56 diagnose these and merely crashes. */
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57 return _URC_FATAL_PHASE2_ERROR;
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58
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59 /* Unwind successful. Run the personality routine, if any. */
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60 if (fs.personality)
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61 {
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62 code = (*fs.personality) (1, _UA_CLEANUP_PHASE | match_handler,
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63 exc->exception_class, exc, context);
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64 if (code == _URC_INSTALL_CONTEXT)
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65 break;
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66 if (code != _URC_CONTINUE_UNWIND)
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67 return _URC_FATAL_PHASE2_ERROR;
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68 }
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69
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70 /* Don't let us unwind past the handler context. */
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71 gcc_assert (!match_handler);
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72
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73 uw_update_context (context, &fs);
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74 }
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75
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76 return code;
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77 }
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78
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79 /* Raise an exception, passing along the given exception object. */
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80
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81 _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
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82 _Unwind_RaiseException(struct _Unwind_Exception *exc)
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83 {
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84 struct _Unwind_Context this_context, cur_context;
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85 _Unwind_Reason_Code code;
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86
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87 /* Set up this_context to describe the current stack frame. */
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88 uw_init_context (&this_context);
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89 cur_context = this_context;
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90
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91 /* Phase 1: Search. Unwind the stack, calling the personality routine
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92 with the _UA_SEARCH_PHASE flag set. Do not modify the stack yet. */
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93 while (1)
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94 {
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95 _Unwind_FrameState fs;
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96
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97 /* Set up fs to describe the FDE for the caller of cur_context. The
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98 first time through the loop, that means __cxa_throw. */
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99 code = uw_frame_state_for (&cur_context, &fs);
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100
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101 if (code == _URC_END_OF_STACK)
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102 /* Hit end of stack with no handler found. */
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103 return _URC_END_OF_STACK;
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104
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105 if (code != _URC_NO_REASON)
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106 /* Some error encountered. Usually the unwinder doesn't
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107 diagnose these and merely crashes. */
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108 return _URC_FATAL_PHASE1_ERROR;
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109
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110 /* Unwind successful. Run the personality routine, if any. */
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111 if (fs.personality)
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112 {
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113 code = (*fs.personality) (1, _UA_SEARCH_PHASE, exc->exception_class,
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114 exc, &cur_context);
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115 if (code == _URC_HANDLER_FOUND)
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116 break;
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117 else if (code != _URC_CONTINUE_UNWIND)
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118 return _URC_FATAL_PHASE1_ERROR;
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119 }
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120
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121 /* Update cur_context to describe the same frame as fs. */
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122 uw_update_context (&cur_context, &fs);
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123 }
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124
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125 /* Indicate to _Unwind_Resume and associated subroutines that this
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126 is not a forced unwind. Further, note where we found a handler. */
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127 exc->private_1 = 0;
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128 exc->private_2 = uw_identify_context (&cur_context);
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129
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130 cur_context = this_context;
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131 code = _Unwind_RaiseException_Phase2 (exc, &cur_context);
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132 if (code != _URC_INSTALL_CONTEXT)
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133 return code;
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134
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135 uw_install_context (&this_context, &cur_context);
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136 }
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137
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138
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139 /* Subroutine of _Unwind_ForcedUnwind also invoked from _Unwind_Resume. */
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140
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141 static _Unwind_Reason_Code
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142 _Unwind_ForcedUnwind_Phase2 (struct _Unwind_Exception *exc,
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143 struct _Unwind_Context *context)
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144 {
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145 _Unwind_Stop_Fn stop = (_Unwind_Stop_Fn) (_Unwind_Ptr) exc->private_1;
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146 void *stop_argument = (void *) (_Unwind_Ptr) exc->private_2;
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147 _Unwind_Reason_Code code, stop_code;
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148
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149 while (1)
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150 {
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151 _Unwind_FrameState fs;
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152 int action;
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153
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154 /* Set up fs to describe the FDE for the caller of cur_context. */
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155 code = uw_frame_state_for (context, &fs);
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156 if (code != _URC_NO_REASON && code != _URC_END_OF_STACK)
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157 return _URC_FATAL_PHASE2_ERROR;
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158
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159 /* Unwind successful. */
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160 action = _UA_FORCE_UNWIND | _UA_CLEANUP_PHASE;
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161 if (code == _URC_END_OF_STACK)
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162 action |= _UA_END_OF_STACK;
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163 stop_code = (*stop) (1, action, exc->exception_class, exc,
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164 context, stop_argument);
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165 if (stop_code != _URC_NO_REASON)
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166 return _URC_FATAL_PHASE2_ERROR;
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167
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168 /* Stop didn't want to do anything. Invoke the personality
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169 handler, if applicable, to run cleanups. */
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170 if (code == _URC_END_OF_STACK)
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171 break;
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172
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173 if (fs.personality)
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174 {
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175 code = (*fs.personality) (1, _UA_FORCE_UNWIND | _UA_CLEANUP_PHASE,
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176 exc->exception_class, exc, context);
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177 if (code == _URC_INSTALL_CONTEXT)
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178 break;
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179 if (code != _URC_CONTINUE_UNWIND)
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180 return _URC_FATAL_PHASE2_ERROR;
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181 }
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182
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183 /* Update cur_context to describe the same frame as fs, and discard
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184 the previous context if necessary. */
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185 uw_advance_context (context, &fs);
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186 }
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187
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188 return code;
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189 }
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190
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191
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192 /* Raise an exception for forced unwinding. */
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193
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194 _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
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195 _Unwind_ForcedUnwind (struct _Unwind_Exception *exc,
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196 _Unwind_Stop_Fn stop, void * stop_argument)
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197 {
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198 struct _Unwind_Context this_context, cur_context;
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199 _Unwind_Reason_Code code;
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200
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201 uw_init_context (&this_context);
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202 cur_context = this_context;
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203
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204 exc->private_1 = (_Unwind_Ptr) stop;
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205 exc->private_2 = (_Unwind_Ptr) stop_argument;
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206
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207 code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context);
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208 if (code != _URC_INSTALL_CONTEXT)
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209 return code;
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210
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211 uw_install_context (&this_context, &cur_context);
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212 }
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213
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214
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215 /* Resume propagation of an existing exception. This is used after
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216 e.g. executing cleanup code, and not to implement rethrowing. */
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217
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218 void LIBGCC2_UNWIND_ATTRIBUTE
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219 _Unwind_Resume (struct _Unwind_Exception *exc)
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220 {
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221 struct _Unwind_Context this_context, cur_context;
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222 _Unwind_Reason_Code code;
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223
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224 uw_init_context (&this_context);
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225 cur_context = this_context;
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226
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227 /* Choose between continuing to process _Unwind_RaiseException
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228 or _Unwind_ForcedUnwind. */
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229 if (exc->private_1 == 0)
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230 code = _Unwind_RaiseException_Phase2 (exc, &cur_context);
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231 else
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232 code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context);
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233
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234 gcc_assert (code == _URC_INSTALL_CONTEXT);
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235
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236 uw_install_context (&this_context, &cur_context);
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237 }
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238
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239
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240 /* Resume propagation of an FORCE_UNWIND exception, or to rethrow
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241 a normal exception that was handled. */
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242
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243 _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
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244 _Unwind_Resume_or_Rethrow (struct _Unwind_Exception *exc)
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245 {
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246 struct _Unwind_Context this_context, cur_context;
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247 _Unwind_Reason_Code code;
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248
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249 /* Choose between continuing to process _Unwind_RaiseException
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250 or _Unwind_ForcedUnwind. */
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251 if (exc->private_1 == 0)
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252 return _Unwind_RaiseException (exc);
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253
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254 uw_init_context (&this_context);
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255 cur_context = this_context;
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256
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257 code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context);
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258
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259 gcc_assert (code == _URC_INSTALL_CONTEXT);
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260
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261 uw_install_context (&this_context, &cur_context);
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262 }
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263
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264
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265 /* A convenience function that calls the exception_cleanup field. */
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266
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267 void
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268 _Unwind_DeleteException (struct _Unwind_Exception *exc)
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269 {
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270 if (exc->exception_cleanup)
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271 (*exc->exception_cleanup) (_URC_FOREIGN_EXCEPTION_CAUGHT, exc);
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272 }
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273
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274
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275 /* Perform stack backtrace through unwind data. */
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276
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277 _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
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278 _Unwind_Backtrace(_Unwind_Trace_Fn trace, void * trace_argument)
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279 {
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280 struct _Unwind_Context context;
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281 _Unwind_Reason_Code code;
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282
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283 uw_init_context (&context);
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284
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285 while (1)
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286 {
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287 _Unwind_FrameState fs;
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288
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289 /* Set up fs to describe the FDE for the caller of context. */
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290 code = uw_frame_state_for (&context, &fs);
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291 if (code != _URC_NO_REASON && code != _URC_END_OF_STACK)
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292 return _URC_FATAL_PHASE1_ERROR;
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293
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294 /* Call trace function. */
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295 if ((*trace) (&context, trace_argument) != _URC_NO_REASON)
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296 return _URC_FATAL_PHASE1_ERROR;
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297
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298 /* We're done at end of stack. */
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299 if (code == _URC_END_OF_STACK)
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300 break;
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301
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302 /* Update context to describe the same frame as fs. */
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303 uw_update_context (&context, &fs);
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304 }
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305
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306 return code;
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307 }
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