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 #include "vecprim.h"
  31 #include "vecir.h"
  32
  33 struct function;
  34 struct eh_region_d;
  35 struct pointer_map_t;
  36
  37 /* The type of an exception region.  */
  38 enum eh_region_type
  39 {
  40   /* CLEANUP regions implement e.g. destructors run when exiting a block.
  41      They can be generated from both GIMPLE_TRY_FINALLY and GIMPLE_TRY_CATCH
  42      nodes.  It is expected by the runtime that cleanup regions will *not*
  43      resume normal program flow, but will continue propagation of the
  44      exception.  */
  45   ERT_CLEANUP,
  46
  47   /* TRY regions implement catching an exception.  The list of types associated
  48      with the attached catch handlers is examined in order by the runtime and
  49      control is transfered to the appropriate handler.  Note that a NULL type
  50      list is a catch-all handler, and that it will catch *all* exceptions
  51      including those originating from a different language.  */
  52   ERT_TRY,
  53
  54   /* ALLOWED_EXCEPTIONS regions implement exception filtering, e.g. the
  55      throw(type-list) specification that can be added to C++ functions.
  56      The runtime examines the thrown exception vs the type list, and if
  57      the exception does not match, transfers control to the handler.  The
  58      normal handler for C++ calls __cxa_call_unexpected.  */
  59   ERT_ALLOWED_EXCEPTIONS,
  60
  61   /* MUST_NOT_THROW regions prevent all exceptions from propagating.  This
  62      region type is used in C++ to surround destructors being run inside a
  63      CLEANUP region.  This differs from an ALLOWED_EXCEPTIONS region with
  64      an empty type list in that the runtime is prepared to terminate the
  65      program directly.  We only generate code for MUST_NOT_THROW regions
  66      along control paths that are already handling an exception within the
  67      current function.  */
  68   ERT_MUST_NOT_THROW
  69 };
  70
  71
  72 /* A landing pad for a given exception region.  Any transfer of control
  73    from the EH runtime to the function happens at a landing pad.  */
  74
  75 struct GTY(()) eh_landing_pad_d
  76 {
  77   /* The linked list of all landing pads associated with the region.  */
  78   struct eh_landing_pad_d *next_lp;
  79
  80   /* The region with which this landing pad is associated.  */
  81   struct eh_region_d *region;
  82
  83   /* At the gimple level, the location to which control will be transfered
  84      for this landing pad.  There can be both EH and normal edges into the
  85      block containing the post-landing-pad label.  */
  86   tree post_landing_pad;
  87
  88   /* At the rtl level, the location to which the runtime will transfer
  89      control.  This differs from the post-landing-pad in that the target's
  90      EXCEPTION_RECEIVER pattern will be expanded here, as well as other
  91      bookkeeping specific to exceptions.  There must not be normal edges
  92      into the block containing the landing-pad label.  */
  93   rtx landing_pad;
  94
  95   /* The index of this landing pad within fun->eh->lp_array.  */
  96   int index;
  97 };
  98
  99 /* A catch handler associated with an ERT_TRY region.  */
 100
 101 struct GTY(()) eh_catch_d
 102 {
 103   /* The double-linked list of all catch handlers for the region.  */
 104   struct eh_catch_d *next_catch;
 105   struct eh_catch_d *prev_catch;
 106
 107   /* A TREE_LIST of runtime type objects that this catch handler
 108      will catch, or NULL if all exceptions are caught.  */
 109   tree type_list;
 110
 111   /* A TREE_LIST of INTEGER_CSTs that correspond to the type_list entries,
 112      having been mapped by assign_filter_values.  These integers are to be
 113      compared against the __builtin_eh_filter value.  */
 114   tree filter_list;
 115
 116   /* The code that should be executed if this catch handler matches the
 117      thrown exception.  This label is only maintained until
 118      pass_lower_eh_dispatch, at which point it is cleared.  */
 119   tree label;
 120 };
 121
 122 /* Describes one exception region.  */
 123
 124 struct GTY(()) eh_region_d
 125 {
 126   /* The immediately surrounding region.  */
 127   struct eh_region_d *outer;
 128
 129   /* The list of immediately contained regions.  */
 130   struct eh_region_d *inner;
 131   struct eh_region_d *next_peer;
 132
 133   /* The index of this region within fun->eh->region_array.  */
 134   int index;
 135
 136   /* Each region does exactly one thing.  */
 137   enum eh_region_type type;
 138
 139   /* Holds the action to perform based on the preceding type.  */
 140   union eh_region_u {
 141     struct eh_region_u_try {
 142       /* The double-linked list of all catch handlers for this region.  */
 143       struct eh_catch_d *first_catch;
 144       struct eh_catch_d *last_catch;
 145     } GTY ((tag ("ERT_TRY"))) eh_try;
 146
 147     struct eh_region_u_allowed {
 148       /* A TREE_LIST of runtime type objects allowed to pass.  */
 149       tree type_list;
 150       /* The code that should be executed if the thrown exception does
 151          not match the type list.  This label is only maintained until
 152          pass_lower_eh_dispatch, at which point it is cleared.  */
 153       tree label;
 154       /* The integer that will be passed by the runtime to signal that
 155          we should execute the code at LABEL.  This integer is assigned
 156          by assign_filter_values and is to be compared against the
 157          __builtin_eh_filter value.  */
 158       int filter;
 159     } GTY ((tag ("ERT_ALLOWED_EXCEPTIONS"))) allowed;
 160
 161     struct eh_region_u_must_not_throw {
 162       /* A function decl to be invoked if this region is actually reachable
 163          from within the function, rather than implementable from the runtime.
 164          The normal way for this to happen is for there to be a CLEANUP region
 165          contained within this MUST_NOT_THROW region.  Note that if the
 166          runtime handles the MUST_NOT_THROW region, we have no control over
 167          what termination function is called; it will be decided by the
 168          personality function in effect for this CIE.  */
 169       tree failure_decl;
 170       /* The location assigned to the call of FAILURE_DECL, if expanded.  */
 171       location_t failure_loc;
 172     } GTY ((tag ("ERT_MUST_NOT_THROW"))) must_not_throw;
 173   } GTY ((desc ("%0.type"))) u;
 174
 175   /* The list of landing pads associated with this region.  */
 176   struct eh_landing_pad_d *landing_pads;
 177
 178   /* EXC_PTR and FILTER values copied from the runtime for this region.
 179      Each region gets its own psuedos so that if there are nested exceptions
 180      we do not overwrite the values of the first exception.  */
 181   rtx exc_ptr_reg, filter_reg;
 182
 183   /* True if this region should use __cxa_end_cleanup instead
 184      of _Unwind_Resume.  */
 185   bool use_cxa_end_cleanup;
 186 };
 187
 188 typedef struct eh_landing_pad_d *eh_landing_pad;
 189 typedef struct eh_catch_d *eh_catch;
 190 typedef struct eh_region_d *eh_region;
 191
 192 DEF_VEC_P(eh_region);
 193 DEF_VEC_ALLOC_P(eh_region, gc);
 194 DEF_VEC_ALLOC_P(eh_region, heap);
 195
 196 DEF_VEC_P(eh_landing_pad);
 197 DEF_VEC_ALLOC_P(eh_landing_pad, gc);
 198
 199
 200 /* The exception status for each function.  */
 201
 202 struct GTY(()) eh_status
 203 {
 204   /* The tree of all regions for this function.  */
 205   eh_region region_tree;
 206
 207   /* The same information as an indexable array.  */
 208   VEC(eh_region,gc) *region_array;
 209
 210   /* The landing pads as an indexable array.  */
 211   VEC(eh_landing_pad,gc) *lp_array;
 212
 213   /* At the gimple level, a mapping from gimple statement to landing pad
 214      or must-not-throw region.  See record_stmt_eh_region.  */
 215   htab_t GTY((param_is (struct throw_stmt_node))) throw_stmt_table;
 216
 217   /* All of the runtime type data used by the function.  These objects
 218      are emitted to the lang-specific-data-area for the function.  */
 219   VEC(tree,gc) *ttype_data;
 220
 221   /* The table of all action chains.  These encode the eh_region tree in
 222      a compact form for use by the runtime, and is also emitted to the
 223      lang-specific-data-area.  Note that the ARM EABI uses a different
 224      format for the encoding than all other ports.  */
 225   union eh_status_u {
 226     VEC(tree,gc) * GTY((tag ("1"))) arm_eabi;
 227     VEC(uchar,gc) * GTY((tag ("0"))) other;
 228   } GTY ((desc ("targetm.arm_eabi_unwinder"))) ehspec_data;
 229 };
 230
 231
 232 /* Invokes CALLBACK for every exception handler label.  Only used by old
 233    loop hackery; should not be used by new code.  */
 234 extern void for_each_eh_label (void (*) (rtx));
 235
 236 extern void init_eh_for_function (void);
 237
 238 extern void remove_eh_landing_pad (eh_landing_pad);
 239 extern void remove_eh_handler (eh_region);
 240
 241 extern bool current_function_has_exception_handlers (void);
 242 extern void output_function_exception_table (const char *);
 243
 244 extern rtx expand_builtin_eh_pointer (tree);
 245 extern rtx expand_builtin_eh_filter (tree);
 246 extern rtx expand_builtin_eh_copy_values (tree);
 247 extern void expand_builtin_unwind_init (void);
 248 extern rtx expand_builtin_eh_return_data_regno (tree);
 249 extern rtx expand_builtin_extract_return_addr (tree);
 250 extern void expand_builtin_init_dwarf_reg_sizes (tree);
 251 extern rtx expand_builtin_frob_return_addr (tree);
 252 extern rtx expand_builtin_dwarf_sp_column (void);
 253 extern void expand_builtin_eh_return (tree, tree);
 254 extern void expand_eh_return (void);
 255 extern rtx expand_builtin_extend_pointer (tree);
 256 extern void expand_dw2_landing_pad_for_region (eh_region);
 257
 258 typedef tree (*duplicate_eh_regions_map) (tree, void *);
 259 extern struct pointer_map_t *duplicate_eh_regions
 260   (struct function *, eh_region, int, duplicate_eh_regions_map, void *);
 261
 262 extern void sjlj_emit_function_exit_after (rtx);
 263
 264 extern eh_region gen_eh_region_cleanup (eh_region);
 265 extern eh_region gen_eh_region_try (eh_region);
 266 extern eh_region gen_eh_region_allowed (eh_region, tree);
 267 extern eh_region gen_eh_region_must_not_throw (eh_region);
 268
 269 extern eh_catch gen_eh_region_catch (eh_region, tree);
 270 extern eh_landing_pad gen_eh_landing_pad (eh_region);
 271
 272 extern eh_region get_eh_region_from_number_fn (struct function *, int);
 273 extern eh_region get_eh_region_from_number (int);
 274 extern eh_landing_pad get_eh_landing_pad_from_number_fn (struct function*,int);
 275 extern eh_landing_pad get_eh_landing_pad_from_number (int);
 276 extern eh_region get_eh_region_from_lp_number_fn (struct function *, int);
 277 extern eh_region get_eh_region_from_lp_number (int);
 278
 279 extern eh_region eh_region_outermost (struct function *, eh_region, eh_region);
 280
 281 extern void make_reg_eh_region_note (rtx insn, int ecf_flags, int lp_nr);
 282 extern void make_reg_eh_region_note_nothrow_nononlocal (rtx);
 283
 284 extern void verify_eh_tree (struct function *);
 285 extern void dump_eh_tree (FILE *, struct function *);
 286 void debug_eh_tree (struct function *);
 287 extern void add_type_for_runtime (tree);
 288 extern tree lookup_type_for_runtime (tree);
 289 extern void assign_filter_values (void);
 290
 291 extern eh_region get_eh_region_from_rtx (const_rtx);
 292 extern eh_landing_pad get_eh_landing_pad_from_rtx (const_rtx);
 293
 294 struct GTY(()) throw_stmt_node {
 295   gimple stmt;
 296   int lp_nr;
 297 };
 298
 299 extern struct htab *get_eh_throw_stmt_table (struct function *);
 300 extern void set_eh_throw_stmt_table (struct function *, struct htab *);
 301
 302 enum eh_personality_kind {
 303   eh_personality_none,
 304   eh_personality_any,
 305   eh_personality_lang
 306 };
 307
 308 extern enum eh_personality_kind
 309 function_needs_eh_personality (struct function *);
 310
 311 /* Pre-order iteration within the eh_region tree.  */
 312
 313 static inline eh_region
 314 ehr_next (eh_region r, eh_region start)
 315 {
 316   if (r->inner)
 317     r = r->inner;
 318   else if (r->next_peer && r != start)
 319     r = r->next_peer;
 320   else
 321     {
 322       do
 323         {
 324           r = r->outer;
 325           if (r == start)
 326             return NULL;
 327         }
 328       while (r->next_peer == NULL);
 329       r = r->next_peer;
 330     }
 331   return r;
 332 }
 333
 334 #define FOR_ALL_EH_REGION_AT(R, START) \
 335   for ((R) = (START); (R) != NULL; (R) = ehr_next (R, START))
 336
 337 #define FOR_ALL_EH_REGION_FN(R, FN) \
 338   for ((R) = (FN)->eh->region_tree; (R) != NULL; (R) = ehr_next (R, NULL))
 339
 340 #define FOR_ALL_EH_REGION(R) FOR_ALL_EH_REGION_FN (R, cfun)