gcc/unwind-sjlj.c

   1 /* SJLJ exception handling and frame unwind runtime interface routines.
   2    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
   3    Free Software Foundation, Inc.
   4
   5    This file is part of GCC.
   6
   7    GCC is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2, or (at your option)
  10    any later version.
  11
  12    GCC is distributed in the hope that it will be useful, but WITHOUT
  13    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  15    License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with GCC; see the file COPYING.  If not, write to the Free
  19    Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20    02111-1307, USA.  */
  21
  22 #include "tconfig.h"
  23 #include "tsystem.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "unwind.h"
  27 #include "gthr.h"
  28
  29 #ifdef __USING_SJLJ_EXCEPTIONS__
  30
  31 #ifdef DONT_USE_BUILTIN_SETJMP
  32 #ifndef inhibit_libc
  33 #include <setjmp.h>
  34 #else
  35 typedef void *jmp_buf[JMP_BUF_SIZE];
  36 extern void longjmp(jmp_buf, int) __attribute__((noreturn));
  37 #endif
  38 #else
  39 #define setjmp __builtin_setjmp
  40 #define longjmp __builtin_longjmp
  41 #endif
  42
  43 /* This structure is allocated on the stack of the target function.
  44    This must match the definition created in except.c:init_eh.  */
  45 struct SjLj_Function_Context
  46 {
  47   /* This is the chain through all registered contexts.  It is
  48      filled in by _Unwind_SjLj_Register.  */
  49   struct SjLj_Function_Context *prev;
  50
  51   /* This is assigned in by the target function before every call
  52      to the index of the call site in the lsda.  It is assigned by
  53      the personality routine to the landing pad index.  */
  54   int call_site;
  55
  56   /* This is how data is returned from the personality routine to
  57      the target function's handler.  */
  58   _Unwind_Word data[4];
  59
  60   /* These are filled in once by the target function before any
  61      exceptions are expected to be handled.  */
  62   _Unwind_Personality_Fn personality;
  63   void *lsda;
  64
  65 #ifdef DONT_USE_BUILTIN_SETJMP
  66   /* We don't know what sort of alignment requirements the system
  67      jmp_buf has.  We over estimated in except.c, and now we have
  68      to match that here just in case the system *didn't* have more
  69      restrictive requirements.  */
  70   jmp_buf jbuf __attribute__((aligned));
  71 #else
  72   void *jbuf[];
  73 #endif
  74 };
  75
  76 struct _Unwind_Context
  77 {
  78   struct SjLj_Function_Context *fc;
  79 };
  80
  81 typedef struct
  82 {
  83   _Unwind_Personality_Fn personality;
  84 } _Unwind_FrameState;
  85
  86 \f
  87 /* Manage the chain of registered function contexts.  */
  88
  89 /* Single threaded fallback chain.  */
  90 static struct SjLj_Function_Context *fc_static;
  91
  92 #if __GTHREADS
  93 static __gthread_key_t fc_key;
  94 static int use_fc_key = -1;
  95
  96 static void
  97 fc_key_init (void)
  98 {
  99   use_fc_key = __gthread_key_create (&fc_key, 0) == 0;
 100 }
 101
 102 static void
 103 fc_key_init_once (void)
 104 {
 105   static __gthread_once_t once = __GTHREAD_ONCE_INIT;
 106   if (__gthread_once (&once, fc_key_init) != 0 || use_fc_key < 0)
 107     use_fc_key = 0;
 108 }
 109 #endif
 110
 111 void
 112 _Unwind_SjLj_Register (struct SjLj_Function_Context *fc)
 113 {
 114 #if __GTHREADS
 115   if (use_fc_key < 0)
 116     fc_key_init_once ();
 117
 118   if (use_fc_key)
 119     {
 120       fc->prev = __gthread_getspecific (fc_key);
 121       __gthread_setspecific (fc_key, fc);
 122     }
 123   else
 124 #endif
 125     {
 126       fc->prev = fc_static;
 127       fc_static = fc;
 128     }
 129 }
 130
 131 static inline struct SjLj_Function_Context *
 132 _Unwind_SjLj_GetContext (void)
 133 {
 134 #if __GTHREADS
 135   if (use_fc_key < 0)
 136     fc_key_init_once ();
 137
 138   if (use_fc_key)
 139     return __gthread_getspecific (fc_key);
 140 #endif
 141   return fc_static;
 142 }
 143
 144 static inline void
 145 _Unwind_SjLj_SetContext (struct SjLj_Function_Context *fc)
 146 {
 147 #if __GTHREADS
 148   if (use_fc_key < 0)
 149     fc_key_init_once ();
 150
 151   if (use_fc_key)
 152     __gthread_setspecific (fc_key, fc);
 153   else
 154 #endif
 155     fc_static = fc;
 156 }
 157
 158 void
 159 _Unwind_SjLj_Unregister (struct SjLj_Function_Context *fc)
 160 {
 161   _Unwind_SjLj_SetContext (fc->prev);
 162 }
 163
 164 \f
 165 /* Get/set the return data value at INDEX in CONTEXT.  */
 166
 167 _Unwind_Word
 168 _Unwind_GetGR (struct _Unwind_Context *context, int index)
 169 {
 170   return context->fc->data[index];
 171 }
 172
 173 /* Get the value of the CFA as saved in CONTEXT.  */
 174
 175 _Unwind_Word
 176 _Unwind_GetCFA (struct _Unwind_Context *context)
 177 {
 178   /* ??? Ideally __builtin_setjmp places the CFA in the jmpbuf.  */
 179   return NULL;
 180 }
 181
 182 void
 183 _Unwind_SetGR (struct _Unwind_Context *context, int index, _Unwind_Word val)
 184 {
 185   context->fc->data[index] = val;
 186 }
 187
 188 /* Get the call-site index as saved in CONTEXT.  */
 189
 190 _Unwind_Ptr
 191 _Unwind_GetIP (struct _Unwind_Context *context)
 192 {
 193   return context->fc->call_site + 1;
 194 }
 195
 196 /* Set the return landing pad index in CONTEXT.  */
 197
 198 void
 199 _Unwind_SetIP (struct _Unwind_Context *context, _Unwind_Ptr val)
 200 {
 201   context->fc->call_site = val - 1;
 202 }
 203
 204 void *
 205 _Unwind_GetLanguageSpecificData (struct _Unwind_Context *context)
 206 {
 207   return context->fc->lsda;
 208 }
 209
 210 _Unwind_Ptr
 211 _Unwind_GetRegionStart (struct _Unwind_Context *context __attribute__((unused)) )
 212 {
 213   return 0;
 214 }
 215
 216 void *
 217 _Unwind_FindEnclosingFunction (void *pc)
 218 {
 219   return NULL;
 220 }
 221
 222 #ifndef __ia64__
 223 _Unwind_Ptr
 224 _Unwind_GetDataRelBase (struct _Unwind_Context *context __attribute__((unused)) )
 225 {
 226   return 0;
 227 }
 228
 229 _Unwind_Ptr
 230 _Unwind_GetTextRelBase (struct _Unwind_Context *context __attribute__((unused)) )
 231 {
 232   return 0;
 233 }
 234 #endif
 235 \f
 236 static inline _Unwind_Reason_Code
 237 uw_frame_state_for (struct _Unwind_Context *context, _Unwind_FrameState *fs)
 238 {
 239   if (context->fc == NULL)
 240     {
 241       fs->personality = NULL;
 242       return _URC_END_OF_STACK;
 243     }
 244   else
 245     {
 246       fs->personality = context->fc->personality;
 247       return _URC_NO_REASON;
 248     }
 249 }
 250
 251 static inline void
 252 uw_update_context (struct _Unwind_Context *context,
 253                    _Unwind_FrameState *fs __attribute__((unused)) )
 254 {
 255   context->fc = context->fc->prev;
 256 }
 257
 258 static inline void
 259 uw_init_context (struct _Unwind_Context *context)
 260 {
 261   context->fc = _Unwind_SjLj_GetContext ();
 262 }
 263
 264 /* ??? There appear to be bugs in integrate.c wrt __builtin_longjmp and
 265    virtual-stack-vars.  An inline version of this segfaults on SPARC.  */
 266 #define uw_install_context(CURRENT, TARGET)             \
 267   do                                                    \
 268     {                                                   \
 269       _Unwind_SjLj_SetContext ((TARGET)->fc);           \
 270       longjmp ((TARGET)->fc->jbuf, 1);                  \
 271     }                                                   \
 272   while (0)
 273
 274
 275 static inline _Unwind_Ptr
 276 uw_identify_context (struct _Unwind_Context *context)
 277 {
 278   return (_Unwind_Ptr) context->fc;
 279 }
 280
 281
 282 /* Play games with unwind symbols so that we can have call frame
 283    and sjlj symbols in the same shared library.  Not that you can
 284    use them simultaneously...  */
 285 #define _Unwind_RaiseException          _Unwind_SjLj_RaiseException
 286 #define _Unwind_ForcedUnwind            _Unwind_SjLj_ForcedUnwind
 287 #define _Unwind_Resume                  _Unwind_SjLj_Resume
 288 #define _Unwind_Resume_or_Rethrow       _Unwind_SjLj_Resume_or_Rethrow
 289
 290 #include "unwind.inc"
 291
 292 #endif /* USING_SJLJ_EXCEPTIONS */