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111
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1 /* SJLJ exception handling and frame unwind runtime interface routines.
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2 Copyright (C) 1997-2017 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 #include "tconfig.h"
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26 #include "tsystem.h"
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27 #include "coretypes.h"
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28 #include "tm.h"
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29 #include "libgcc_tm.h"
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30 #include "unwind.h"
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31 #include "gthr.h"
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32
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33 #ifdef __USING_SJLJ_EXCEPTIONS__
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34
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35 #ifdef __LIBGCC_DONT_USE_BUILTIN_SETJMP__
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36 #ifndef inhibit_libc
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37 #include <setjmp.h>
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38 #else
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39 typedef void *jmp_buf[__LIBGCC_JMP_BUF_SIZE__];
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40 extern void longjmp(jmp_buf, int) __attribute__((noreturn));
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41 #endif
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42 #else
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43 #define longjmp __builtin_longjmp
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44 #endif
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45
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46 /* The setjmp side is dealt with in the except.c file. */
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47 #undef setjmp
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48 #define setjmp setjmp_should_not_be_used_in_this_file
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49
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50
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51 /* This structure is allocated on the stack of the target function.
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52 This must match the definition created in except.c:init_eh. */
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53 struct SjLj_Function_Context
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54 {
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55 /* This is the chain through all registered contexts. It is
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56 filled in by _Unwind_SjLj_Register. */
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57 struct SjLj_Function_Context *prev;
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58
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59 /* This is assigned in by the target function before every call
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60 to the index of the call site in the lsda. It is assigned by
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61 the personality routine to the landing pad index. */
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62 int call_site;
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63
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64 /* This is how data is returned from the personality routine to
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65 the target function's handler. */
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66 _Unwind_Word data[4];
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67
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68 /* These are filled in once by the target function before any
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69 exceptions are expected to be handled. */
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70 _Unwind_Personality_Fn personality;
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71 void *lsda;
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72
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73 #ifdef __LIBGCC_DONT_USE_BUILTIN_SETJMP__
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74 /* We don't know what sort of alignment requirements the system
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75 jmp_buf has. We over estimated in except.c, and now we have
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76 to match that here just in case the system *didn't* have more
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77 restrictive requirements. */
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78 jmp_buf jbuf __attribute__((aligned));
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79 #else
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80 void *jbuf[];
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81 #endif
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82 };
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83
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84 struct _Unwind_Context
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85 {
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86 struct SjLj_Function_Context *fc;
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87 };
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88
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89 typedef struct
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90 {
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91 _Unwind_Personality_Fn personality;
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92 } _Unwind_FrameState;
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93
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94
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95 /* Manage the chain of registered function contexts. */
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96
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97 /* Single threaded fallback chain. */
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98 static struct SjLj_Function_Context *fc_static;
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99
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100 #if __GTHREADS
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101 static __gthread_key_t fc_key;
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102 static int use_fc_key = -1;
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103
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104 static void
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105 fc_key_init (void)
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106 {
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107 use_fc_key = __gthread_key_create (&fc_key, 0) == 0;
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108 }
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109
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110 static void
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111 fc_key_init_once (void)
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112 {
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113 static __gthread_once_t once = __GTHREAD_ONCE_INIT;
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114 if (__gthread_once (&once, fc_key_init) != 0 || use_fc_key < 0)
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115 use_fc_key = 0;
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116 }
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117 #endif
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118
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119 void
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120 _Unwind_SjLj_Register (struct SjLj_Function_Context *fc)
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121 {
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122 #if __GTHREADS
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123 if (use_fc_key < 0)
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124 fc_key_init_once ();
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125
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126 if (use_fc_key)
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127 {
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128 fc->prev = __gthread_getspecific (fc_key);
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129 __gthread_setspecific (fc_key, fc);
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130 }
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131 else
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132 #endif
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133 {
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134 fc->prev = fc_static;
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135 fc_static = fc;
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136 }
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137 }
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138
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139 static inline struct SjLj_Function_Context *
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140 _Unwind_SjLj_GetContext (void)
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141 {
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142 #if __GTHREADS
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143 if (use_fc_key < 0)
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144 fc_key_init_once ();
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145
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146 if (use_fc_key)
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147 return __gthread_getspecific (fc_key);
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148 #endif
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149 return fc_static;
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150 }
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151
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152 static inline void
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153 _Unwind_SjLj_SetContext (struct SjLj_Function_Context *fc)
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154 {
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155 #if __GTHREADS
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156 if (use_fc_key < 0)
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157 fc_key_init_once ();
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158
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159 if (use_fc_key)
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160 __gthread_setspecific (fc_key, fc);
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161 else
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162 #endif
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163 fc_static = fc;
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164 }
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165
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166 void
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167 _Unwind_SjLj_Unregister (struct SjLj_Function_Context *fc)
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168 {
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169 _Unwind_SjLj_SetContext (fc->prev);
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170 }
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171
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172
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173 /* Get/set the return data value at INDEX in CONTEXT. */
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174
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175 _Unwind_Word
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176 _Unwind_GetGR (struct _Unwind_Context *context, int index)
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177 {
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178 return context->fc->data[index];
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179 }
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180
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181 /* Get the value of the CFA as saved in CONTEXT. */
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182
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183 _Unwind_Word
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184 _Unwind_GetCFA (struct _Unwind_Context *context __attribute__((unused)))
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185 {
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186 /* ??? Ideally __builtin_setjmp places the CFA in the jmpbuf. */
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187
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188 #ifndef __LIBGCC_DONT_USE_BUILTIN_SETJMP__
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189 /* This is a crude imitation of the CFA: the saved stack pointer.
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190 This is roughly the CFA of the frame before CONTEXT. When using the
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191 DWARF-2 unwinder _Unwind_GetCFA returns the CFA of the frame described
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192 by CONTEXT instead; but for DWARF-2 the cleanups associated with
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193 CONTEXT have already been run, and for SJLJ they have not yet been. */
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194 if (context->fc != NULL)
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195 return (_Unwind_Word) context->fc->jbuf[2];
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196 #endif
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197
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198 /* Otherwise we're out of luck for now. */
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199 return (_Unwind_Word) 0;
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200 }
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201
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202 void
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203 _Unwind_SetGR (struct _Unwind_Context *context, int index, _Unwind_Word val)
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204 {
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205 context->fc->data[index] = val;
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206 }
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207
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208 /* Get the call-site index as saved in CONTEXT. */
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209
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210 _Unwind_Ptr
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211 _Unwind_GetIP (struct _Unwind_Context *context)
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212 {
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213 return context->fc->call_site + 1;
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214 }
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215
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216 _Unwind_Ptr
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217 _Unwind_GetIPInfo (struct _Unwind_Context *context, int *ip_before_insn)
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218 {
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219 *ip_before_insn = 0;
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220 if (context->fc != NULL)
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221 return context->fc->call_site + 1;
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222 else
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223 return 0;
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224 }
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225
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226 /* Set the return landing pad index in CONTEXT. */
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227
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228 void
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229 _Unwind_SetIP (struct _Unwind_Context *context, _Unwind_Ptr val)
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230 {
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231 context->fc->call_site = val - 1;
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232 }
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233
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234 void *
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235 _Unwind_GetLanguageSpecificData (struct _Unwind_Context *context)
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236 {
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237 return context->fc->lsda;
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238 }
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239
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240 _Unwind_Ptr
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241 _Unwind_GetRegionStart (struct _Unwind_Context *context __attribute__((unused)) )
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242 {
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243 return 0;
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244 }
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245
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246 void *
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247 _Unwind_FindEnclosingFunction (void *pc __attribute__((unused)))
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248 {
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249 return NULL;
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250 }
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251
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252 #ifndef __ia64__
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253 _Unwind_Ptr
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254 _Unwind_GetDataRelBase (struct _Unwind_Context *context __attribute__((unused)) )
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255 {
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256 return 0;
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257 }
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258
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259 _Unwind_Ptr
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260 _Unwind_GetTextRelBase (struct _Unwind_Context *context __attribute__((unused)) )
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261 {
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262 return 0;
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263 }
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264 #endif
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265
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266 static inline _Unwind_Reason_Code
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267 uw_frame_state_for (struct _Unwind_Context *context, _Unwind_FrameState *fs)
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268 {
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269 if (context->fc == NULL)
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270 {
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271 fs->personality = NULL;
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272 return _URC_END_OF_STACK;
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273 }
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274 else
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275 {
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276 fs->personality = context->fc->personality;
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277 return _URC_NO_REASON;
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278 }
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279 }
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280
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281 static inline void
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282 uw_update_context (struct _Unwind_Context *context,
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283 _Unwind_FrameState *fs __attribute__((unused)) )
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284 {
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285 context->fc = context->fc->prev;
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286 }
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287
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288 static void
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289 uw_advance_context (struct _Unwind_Context *context, _Unwind_FrameState *fs)
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290 {
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291 _Unwind_SjLj_Unregister (context->fc);
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292 uw_update_context (context, fs);
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293 }
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294
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295 static inline void
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296 uw_init_context (struct _Unwind_Context *context)
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297 {
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298 context->fc = _Unwind_SjLj_GetContext ();
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299 }
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300
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301 static void __attribute__((noreturn))
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302 uw_install_context (struct _Unwind_Context *current __attribute__((unused)),
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303 struct _Unwind_Context *target)
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304 {
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305 _Unwind_SjLj_SetContext (target->fc);
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306 longjmp (target->fc->jbuf, 1);
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307 }
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308
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309 static inline _Unwind_Ptr
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310 uw_identify_context (struct _Unwind_Context *context)
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311 {
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312 return (_Unwind_Ptr) context->fc;
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313 }
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314
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315
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316 /* Play games with unwind symbols so that we can have call frame
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317 and sjlj symbols in the same shared library. Not that you can
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318 use them simultaneously... */
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319 #define _Unwind_RaiseException _Unwind_SjLj_RaiseException
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320 #define _Unwind_ForcedUnwind _Unwind_SjLj_ForcedUnwind
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321 #define _Unwind_Resume _Unwind_SjLj_Resume
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322 #define _Unwind_Resume_or_Rethrow _Unwind_SjLj_Resume_or_Rethrow
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323
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324 #include "unwind.inc"
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325
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326 #endif /* USING_SJLJ_EXCEPTIONS */
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