gcc/unwind-sjlj.c

   1 /* DWARF2 exception handling and frame unwind runtime interface routines.
   2    Copyright (C) 1997, 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
   3
   4    This file is part of GNU CC.
   5
   6    GNU CC is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    GNU CC is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with GNU CC; see the file COPYING.  If not, write to
  18    the Free Software Foundation, 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include "tconfig.h"
  22 #include "tsystem.h"
  23 #include "unwind.h"
  24 #include "gthr.h"
  25
  26 #if USING_SJLJ_EXCEPTIONS
  27
  28 #ifdef DONT_USE_BUILTIN_SETJMP
  29 #include <setjmp.h>
  30 #else
  31 #define setjmp __builtin_setjmp
  32 #define longjmp __builtin_longjmp
  33 #endif
  34
  35 /* This structure is allocated on the stack of the target function.
  36    This must match the definition created in except.c:init_eh.  */
  37 struct SjLj_Function_Context
  38 {
  39   /* This is the chain through all registered contexts.  It is
  40      filled in by _Unwind_SjLj_Register.  */
  41   struct SjLj_Function_Context *prev;
  42
  43   /* This is assigned in by the target function before every call
  44      to the index of the call site in the lsda.  It is assigned by
  45      the personality routine to the landing pad index.  */
  46   int call_site;
  47
  48   /* This is how data is returned from the personality routine to
  49      the target function's handler.  */
  50   _Unwind_Word data[4];
  51
  52   /* These are filled in once by the target function before any
  53      exceptions are expected to be handled.  */
  54   _Unwind_Personality_Fn personality;
  55   void *lsda;
  56
  57 #ifdef DONT_USE_BUILTIN_SETJMP
  58   /* We don't know what sort of alignment requirements the system
  59      jmp_buf has.  We over estimated in except.c, and now we have
  60      to match that here just in case the system *didn't* have more
  61      restrictive requirements.  */
  62   jmp_buf jbuf __attribute__((aligned));
  63 #else
  64   void *jbuf[];
  65 #endif
  66 };
  67
  68 struct _Unwind_Context
  69 {
  70   struct SjLj_Function_Context *fc;
  71 };
  72
  73 typedef struct
  74 {
  75   _Unwind_Personality_Fn personality;
  76 } _Unwind_FrameState;
  77
  78 \f
  79 /* Manage the chain of registered function contexts.  */
  80
  81 /* Single threaded fallback chain.  */
  82 static struct SjLj_Function_Context *fc_static;
  83
  84 #if __GTHREADS
  85 static __gthread_key_t fc_key;
  86 static int use_fc_key = -1;
  87
  88 static void
  89 fc_key_dtor (void *ptr)
  90 {
  91   __gthread_key_dtor (fc_key, ptr);
  92 }
  93
  94 static void
  95 fc_key_init (void)
  96 {
  97   use_fc_key = __gthread_key_create (&fc_key, fc_key_dtor) == 0;
  98 }
  99
 100 static void
 101 fc_key_init_once (void)
 102 {
 103   static __gthread_once_t once = __GTHREAD_ONCE_INIT;
 104   if (__gthread_once (&once, fc_key_init) != 0 || use_fc_key < 0)
 105     use_fc_key = 0;
 106 }
 107 #endif
 108
 109 void
 110 _Unwind_SjLj_Register (struct SjLj_Function_Context *fc)
 111 {
 112 #if __GTHREADS
 113   if (use_fc_key < 0)
 114     fc_key_init_once ();
 115
 116   if (use_fc_key)
 117     {
 118       fc->prev = __gthread_getspecific (fc_key);
 119       __gthread_setspecific (fc_key, fc);
 120     }
 121   else
 122 #endif
 123     {
 124       fc->prev = fc_static;
 125       fc_static = fc;
 126     }
 127 }
 128
 129 static inline struct SjLj_Function_Context *
 130 _Unwind_SjLj_GetContext (void)
 131 {
 132 #if __GTHREADS
 133   if (use_fc_key < 0)
 134     fc_key_init_once ();
 135
 136   if (use_fc_key)
 137     return __gthread_getspecific (fc_key);
 138 #endif
 139   return fc_static;
 140 }
 141
 142 static inline void
 143 _Unwind_SjLj_SetContext (struct SjLj_Function_Context *fc)
 144 {
 145 #if __GTHREADS
 146   if (use_fc_key < 0)
 147     fc_key_init_once ();
 148
 149   if (use_fc_key)
 150     __gthread_setspecific (fc_key, fc);
 151   else
 152 #endif
 153     fc_static = fc;
 154 }
 155
 156 void
 157 _Unwind_SjLj_Unregister (struct SjLj_Function_Context *fc)
 158 {
 159   _Unwind_SjLj_SetContext (fc->prev);
 160 }
 161
 162 \f
 163 /* Get/set the return data value at INDEX in CONTEXT.  */
 164
 165 _Unwind_Word
 166 _Unwind_GetGR (struct _Unwind_Context *context, int index)
 167 {
 168   return context->fc->data[index];
 169 }
 170
 171 void
 172 _Unwind_SetGR (struct _Unwind_Context *context, int index, _Unwind_Word val)
 173 {
 174   context->fc->data[index] = val;
 175 }
 176
 177 /* Get the call-site index as saved in CONTEXT.  */
 178
 179 _Unwind_Ptr
 180 _Unwind_GetIP (struct _Unwind_Context *context)
 181 {
 182   return context->fc->call_site + 1;
 183 }
 184
 185 /* Set the return landing pad index in CONTEXT.  */
 186
 187 void
 188 _Unwind_SetIP (struct _Unwind_Context *context, _Unwind_Ptr val)
 189 {
 190   context->fc->call_site = val - 1;
 191 }
 192
 193 void *
 194 _Unwind_GetLanguageSpecificData (struct _Unwind_Context *context)
 195 {
 196   return context->fc->lsda;
 197 }
 198
 199 _Unwind_Ptr
 200 _Unwind_GetRegionStart (struct _Unwind_Context *context)
 201 {
 202   return 0;
 203 }
 204
 205 #ifndef __ia64__
 206 _Unwind_Ptr
 207 _Unwind_GetDataRelBase (struct _Unwind_Context *context)
 208 {
 209   return 0;
 210 }
 211
 212 _Unwind_Ptr
 213 _Unwind_GetTextRelBase (struct _Unwind_Context *context)
 214 {
 215   return 0;
 216 }
 217 #endif
 218 \f
 219 static inline _Unwind_Reason_Code
 220 uw_frame_state_for (struct _Unwind_Context *context, _Unwind_FrameState *fs)
 221 {
 222   if (context->fc == NULL)
 223     {
 224       fs->personality = NULL;
 225       return _URC_END_OF_STACK;
 226     }
 227   else
 228     {
 229       fs->personality = context->fc->personality;
 230       return _URC_NO_REASON;
 231     }
 232 }
 233
 234 static inline void
 235 uw_update_context (struct _Unwind_Context *context,
 236                    _Unwind_FrameState *fs __attribute__((unused)) )
 237 {
 238   context->fc = context->fc->prev;
 239 }
 240
 241 static inline void
 242 uw_init_context (struct _Unwind_Context *context)
 243 {
 244   context->fc = _Unwind_SjLj_GetContext ();
 245 }
 246
 247 /* ??? There appear to be bugs in integrate.c wrt __builtin_longjmp and
 248    virtual-stack-vars.  An inline version of this segfaults on Sparc.  */
 249 #define uw_install_context(CURRENT, TARGET)     \
 250   do {                                          \
 251     _Unwind_SjLj_SetContext ((TARGET)->fc);     \
 252     longjmp ((TARGET)->fc->jbuf, 1);            \
 253   } while (0)
 254
 255
 256 static inline _Unwind_Ptr
 257 uw_identify_context (struct _Unwind_Context *context)
 258 {
 259   return (_Unwind_Ptr) context->fc;
 260 }
 261
 262
 263 /* Play games with unwind symbols so that we can have call frame
 264    and sjlj symbols in the same shared library.  Not that you can
 265    use them simultaneously...  */
 266 #define _Unwind_RaiseException          _Unwind_SjLj_RaiseException
 267 #define _Unwind_ForcedUnwind            _Unwind_SjLj_ForcedUnwind
 268 #define _Unwind_Resume                  _Unwind_SjLj_Resume
 269
 270 #include "unwind.inc"
 271
 272 #endif /* USING_SJLJ_EXCEPTIONS */