gcc/except.h

   1 /* Exception Handling interface routines.
   2    Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
   3    2007, 2008, 2009, 2010  Free Software Foundation, Inc.
   4    Contributed by Mike Stump <mrs@cygnus.com>.
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 /* No include guards here, but define an include file marker anyway, so
  23    that the compiler can keep track of where this file is included.  This
  24    is e.g. used to avoid including this file in front-end specific files.  */
  25 #ifndef GCC_EXCEPT_H
  26 #  define GCC_EXCEPT_H
  27 #endif
  28
  29 #include "hashtab.h"
  30
  31 struct function;
  32 struct eh_region_d;
  33 struct pointer_map_t;
  34
  35 /* The type of an exception region.  */
  36 enum eh_region_type
  37 {
  38   /* CLEANUP regions implement e.g. destructors run when exiting a block.
  39      They can be generated from both GIMPLE_TRY_FINALLY and GIMPLE_TRY_CATCH
  40      nodes.  It is expected by the runtime that cleanup regions will *not*
  41      resume normal program flow, but will continue propagation of the
  42      exception.  */
  43   ERT_CLEANUP,
  44
  45   /* TRY regions implement catching an exception.  The list of types associated
  46      with the attached catch handlers is examined in order by the runtime and
  47      control is transferred to the appropriate handler.  Note that a NULL type
  48      list is a catch-all handler, and that it will catch *all* exceptions
  49      including those originating from a different language.  */
  50   ERT_TRY,
  51
  52   /* ALLOWED_EXCEPTIONS regions implement exception filtering, e.g. the
  53      throw(type-list) specification that can be added to C++ functions.
  54      The runtime examines the thrown exception vs the type list, and if
  55      the exception does not match, transfers control to the handler.  The
  56      normal handler for C++ calls __cxa_call_unexpected.  */
  57   ERT_ALLOWED_EXCEPTIONS,
  58
  59   /* MUST_NOT_THROW regions prevent all exceptions from propagating.  This
  60      region type is used in C++ to surround destructors being run inside a
  61      CLEANUP region.  This differs from an ALLOWED_EXCEPTIONS region with
  62      an empty type list in that the runtime is prepared to terminate the
  63      program directly.  We only generate code for MUST_NOT_THROW regions
  64      along control paths that are already handling an exception within the
  65      current function.  */
  66   ERT_MUST_NOT_THROW
  67 };
  68
  69
  70 /* A landing pad for a given exception region.  Any transfer of control
  71    from the EH runtime to the function happens at a landing pad.  */
  72
  73 struct GTY(()) eh_landing_pad_d
  74 {
  75   /* The linked list of all landing pads associated with the region.  */
  76   struct eh_landing_pad_d *next_lp;
  77
  78   /* The region with which this landing pad is associated.  */
  79   struct eh_region_d *region;
  80
  81   /* At the gimple level, the location to which control will be transferred
  82      for this landing pad.  There can be both EH and normal edges into the
  83      block containing the post-landing-pad label.  */
  84   tree post_landing_pad;
  85
  86   /* At the rtl level, the location to which the runtime will transfer
  87      control.  This differs from the post-landing-pad in that the target's
  88      EXCEPTION_RECEIVER pattern will be expanded here, as well as other
  89      bookkeeping specific to exceptions.  There must not be normal edges
  90      into the block containing the landing-pad label.  */
  91   rtx landing_pad;
  92
  93   /* The index of this landing pad within fun->eh->lp_array.  */
  94   int index;
  95 };
  96
  97 /* A catch handler associated with an ERT_TRY region.  */
  98
  99 struct GTY(()) eh_catch_d
 100 {
 101   /* The double-linked list of all catch handlers for the region.  */
 102   struct eh_catch_d *next_catch;
 103   struct eh_catch_d *prev_catch;
 104
 105   /* A TREE_LIST of runtime type objects that this catch handler
 106      will catch, or NULL if all exceptions are caught.  */
 107   tree type_list;
 108
 109   /* A TREE_LIST of INTEGER_CSTs that correspond to the type_list entries,
 110      having been mapped by assign_filter_values.  These integers are to be
 111      compared against the __builtin_eh_filter value.  */
 112   tree filter_list;
 113
 114   /* The code that should be executed if this catch handler matches the
 115      thrown exception.  This label is only maintained until
 116      pass_lower_eh_dispatch, at which point it is cleared.  */
 117   tree label;
 118 };
 119
 120 /* Describes one exception region.  */
 121
 122 struct GTY(()) eh_region_d
 123 {
 124   /* The immediately surrounding region.  */
 125   struct eh_region_d *outer;
 126
 127   /* The list of immediately contained regions.  */
 128   struct eh_region_d *inner;
 129   struct eh_region_d *next_peer;
 130
 131   /* The index of this region within fun->eh->region_array.  */
 132   int index;
 133
 134   /* Each region does exactly one thing.  */
 135   enum eh_region_type type;
 136
 137   /* Holds the action to perform based on the preceding type.  */
 138   union eh_region_u {
 139     struct eh_region_u_try {
 140       /* The double-linked list of all catch handlers for this region.  */
 141       struct eh_catch_d *first_catch;
 142       struct eh_catch_d *last_catch;
 143     } GTY ((tag ("ERT_TRY"))) eh_try;
 144
 145     struct eh_region_u_allowed {
 146       /* A TREE_LIST of runtime type objects allowed to pass.  */
 147       tree type_list;
 148       /* The code that should be executed if the thrown exception does
 149          not match the type list.  This label is only maintained until
 150          pass_lower_eh_dispatch, at which point it is cleared.  */
 151       tree label;
 152       /* The integer that will be passed by the runtime to signal that
 153          we should execute the code at LABEL.  This integer is assigned
 154          by assign_filter_values and is to be compared against the
 155          __builtin_eh_filter value.  */
 156       int filter;
 157     } GTY ((tag ("ERT_ALLOWED_EXCEPTIONS"))) allowed;
 158
 159     struct eh_region_u_must_not_throw {
 160       /* A function decl to be invoked if this region is actually reachable
 161          from within the function, rather than implementable from the runtime.
 162          The normal way for this to happen is for there to be a CLEANUP region
 163          contained within this MUST_NOT_THROW region.  Note that if the
 164          runtime handles the MUST_NOT_THROW region, we have no control over
 165          what termination function is called; it will be decided by the
 166          personality function in effect for this CIE.  */
 167       tree failure_decl;
 168       /* The location assigned to the call of FAILURE_DECL, if expanded.  */
 169       location_t failure_loc;
 170     } GTY ((tag ("ERT_MUST_NOT_THROW"))) must_not_throw;
 171   } GTY ((desc ("%0.type"))) u;
 172
 173   /* The list of landing pads associated with this region.  */
 174   struct eh_landing_pad_d *landing_pads;
 175
 176   /* EXC_PTR and FILTER values copied from the runtime for this region.
 177      Each region gets its own psuedos so that if there are nested exceptions
 178      we do not overwrite the values of the first exception.  */
 179   rtx exc_ptr_reg, filter_reg;
 180
 181   /* True if this region should use __cxa_end_cleanup instead
 182      of _Unwind_Resume.  */
 183   bool use_cxa_end_cleanup;
 184 };
 185
 186 typedef struct eh_landing_pad_d *eh_landing_pad;
 187 typedef struct eh_catch_d *eh_catch;
 188 typedef struct eh_region_d *eh_region;
 189
 190
 191
 192
 193 /* The exception status for each function.  */
 194
 195 struct GTY(()) eh_status
 196 {
 197   /* The tree of all regions for this function.  */
 198   eh_region region_tree;
 199
 200   /* The same information as an indexable array.  */
 201   vec<eh_region, va_gc> *region_array;
 202
 203   /* The landing pads as an indexable array.  */
 204   vec<eh_landing_pad, va_gc> *lp_array;
 205
 206   /* At the gimple level, a mapping from gimple statement to landing pad
 207      or must-not-throw region.  See record_stmt_eh_region.  */
 208   htab_t GTY((param_is (struct throw_stmt_node))) throw_stmt_table;
 209
 210   /* All of the runtime type data used by the function.  These objects
 211      are emitted to the lang-specific-data-area for the function.  */
 212   vec<tree, va_gc> *ttype_data;
 213
 214   /* The table of all action chains.  These encode the eh_region tree in
 215      a compact form for use by the runtime, and is also emitted to the
 216      lang-specific-data-area.  Note that the ARM EABI uses a different
 217      format for the encoding than all other ports.  */
 218   union eh_status_u {
 219     vec<tree, va_gc> *GTY((tag ("1"))) arm_eabi;
 220     vec<uchar, va_gc> *GTY((tag ("0"))) other;
 221   } GTY ((desc ("targetm.arm_eabi_unwinder"))) ehspec_data;
 222 };
 223
 224
 225 /* Invokes CALLBACK for every exception handler label.  Only used by old
 226    loop hackery; should not be used by new code.  */
 227 extern void for_each_eh_label (void (*) (rtx));
 228
 229 extern void init_eh_for_function (void);
 230
 231 extern void remove_eh_landing_pad (eh_landing_pad);
 232 extern void remove_eh_handler (eh_region);
 233
 234 extern bool current_function_has_exception_handlers (void);
 235 extern void output_function_exception_table (const char *);
 236
 237 extern rtx expand_builtin_eh_pointer (tree);
 238 extern rtx expand_builtin_eh_filter (tree);
 239 extern rtx expand_builtin_eh_copy_values (tree);
 240 extern void expand_builtin_unwind_init (void);
 241 extern rtx expand_builtin_eh_return_data_regno (tree);
 242 extern rtx expand_builtin_extract_return_addr (tree);
 243 extern void expand_builtin_init_dwarf_reg_sizes (tree);
 244 extern rtx expand_builtin_frob_return_addr (tree);
 245 extern rtx expand_builtin_dwarf_sp_column (void);
 246 extern void expand_builtin_eh_return (tree, tree);
 247 extern void expand_eh_return (void);
 248 extern rtx expand_builtin_extend_pointer (tree);
 249 extern void expand_dw2_landing_pad_for_region (eh_region);
 250
 251 typedef tree (*duplicate_eh_regions_map) (tree, void *);
 252 extern struct pointer_map_t *duplicate_eh_regions
 253   (struct function *, eh_region, int, duplicate_eh_regions_map, void *);
 254
 255 extern void sjlj_emit_function_exit_after (rtx);
 256
 257 extern eh_region gen_eh_region_cleanup (eh_region);
 258 extern eh_region gen_eh_region_try (eh_region);
 259 extern eh_region gen_eh_region_allowed (eh_region, tree);
 260 extern eh_region gen_eh_region_must_not_throw (eh_region);
 261
 262 extern eh_catch gen_eh_region_catch (eh_region, tree);
 263 extern eh_landing_pad gen_eh_landing_pad (eh_region);
 264
 265 extern eh_region get_eh_region_from_number_fn (struct function *, int);
 266 extern eh_region get_eh_region_from_number (int);
 267 extern eh_landing_pad get_eh_landing_pad_from_number_fn (struct function*,int);
 268 extern eh_landing_pad get_eh_landing_pad_from_number (int);
 269 extern eh_region get_eh_region_from_lp_number_fn (struct function *, int);
 270 extern eh_region get_eh_region_from_lp_number (int);
 271
 272 extern eh_region eh_region_outermost (struct function *, eh_region, eh_region);
 273
 274 extern void make_reg_eh_region_note (rtx insn, int ecf_flags, int lp_nr);
 275 extern void make_reg_eh_region_note_nothrow_nononlocal (rtx);
 276
 277 extern void verify_eh_tree (struct function *);
 278 extern void dump_eh_tree (FILE *, struct function *);
 279 void debug_eh_tree (struct function *);
 280 extern void add_type_for_runtime (tree);
 281 extern tree lookup_type_for_runtime (tree);
 282 extern void assign_filter_values (void);
 283
 284 extern eh_region get_eh_region_from_rtx (const_rtx);
 285 extern eh_landing_pad get_eh_landing_pad_from_rtx (const_rtx);
 286
 287 extern void finish_eh_generation (void);
 288
 289 struct GTY(()) throw_stmt_node {
 290   gimple stmt;
 291   int lp_nr;
 292 };
 293
 294 extern struct htab *get_eh_throw_stmt_table (struct function *);
 295 extern void set_eh_throw_stmt_table (struct function *, struct htab *);
 296
 297 enum eh_personality_kind {
 298   eh_personality_none,
 299   eh_personality_any,
 300   eh_personality_lang
 301 };
 302
 303 extern enum eh_personality_kind
 304 function_needs_eh_personality (struct function *);
 305
 306 /* Pre-order iteration within the eh_region tree.  */
 307
 308 static inline eh_region
 309 ehr_next (eh_region r, eh_region start)
 310 {
 311   if (r->inner)
 312     r = r->inner;
 313   else if (r->next_peer && r != start)
 314     r = r->next_peer;
 315   else
 316     {
 317       do
 318         {
 319           r = r->outer;
 320           if (r == start)
 321             return NULL;
 322         }
 323       while (r->next_peer == NULL);
 324       r = r->next_peer;
 325     }
 326   return r;
 327 }
 328
 329 #define FOR_ALL_EH_REGION_AT(R, START) \
 330   for ((R) = (START); (R) != NULL; (R) = ehr_next (R, START))
 331
 332 #define FOR_ALL_EH_REGION_FN(R, FN) \
 333   for ((R) = (FN)->eh->region_tree; (R) != NULL; (R) = ehr_next (R, NULL))
 334
 335 #define FOR_ALL_EH_REGION(R) FOR_ALL_EH_REGION_FN (R, cfun)