gcc/except.h

   1 /* Exception Handling interface routines.
   2    Copyright (C) 1996-2014 Free Software Foundation, Inc.
   3    Contributed by Mike Stump <mrs@cygnus.com>.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 /* No include guards here, but define an include file marker anyway, so
  22    that the compiler can keep track of where this file is included.  This
  23    is e.g. used to avoid including this file in front-end specific files.  */
  24 #ifndef GCC_EXCEPT_H
  25 #  define GCC_EXCEPT_H
  26 #endif
  27
  28 #include "hash-map.h"
  29 #include "hashtab.h"
  30
  31 struct function;
  32 struct eh_region_d;
  33
  34 /* The type of an exception region.  */
  35 enum eh_region_type
  36 {
  37   /* CLEANUP regions implement e.g. destructors run when exiting a block.
  38      They can be generated from both GIMPLE_TRY_FINALLY and GIMPLE_TRY_CATCH
  39      nodes.  It is expected by the runtime that cleanup regions will *not*
  40      resume normal program flow, but will continue propagation of the
  41      exception.  */
  42   ERT_CLEANUP,
  43
  44   /* TRY regions implement catching an exception.  The list of types associated
  45      with the attached catch handlers is examined in order by the runtime and
  46      control is transferred to the appropriate handler.  Note that a NULL type
  47      list is a catch-all handler, and that it will catch *all* exceptions
  48      including those originating from a different language.  */
  49   ERT_TRY,
  50
  51   /* ALLOWED_EXCEPTIONS regions implement exception filtering, e.g. the
  52      throw(type-list) specification that can be added to C++ functions.
  53      The runtime examines the thrown exception vs the type list, and if
  54      the exception does not match, transfers control to the handler.  The
  55      normal handler for C++ calls __cxa_call_unexpected.  */
  56   ERT_ALLOWED_EXCEPTIONS,
  57
  58   /* MUST_NOT_THROW regions prevent all exceptions from propagating.  This
  59      region type is used in C++ to surround destructors being run inside a
  60      CLEANUP region.  This differs from an ALLOWED_EXCEPTIONS region with
  61      an empty type list in that the runtime is prepared to terminate the
  62      program directly.  We only generate code for MUST_NOT_THROW regions
  63      along control paths that are already handling an exception within the
  64      current function.  */
  65   ERT_MUST_NOT_THROW
  66 };
  67
  68
  69 /* A landing pad for a given exception region.  Any transfer of control
  70    from the EH runtime to the function happens at a landing pad.  */
  71
  72 struct GTY(()) eh_landing_pad_d
  73 {
  74   /* The linked list of all landing pads associated with the region.  */
  75   struct eh_landing_pad_d *next_lp;
  76
  77   /* The region with which this landing pad is associated.  */
  78   struct eh_region_d *region;
  79
  80   /* At the gimple level, the location to which control will be transferred
  81      for this landing pad.  There can be both EH and normal edges into the
  82      block containing the post-landing-pad label.  */
  83   tree post_landing_pad;
  84
  85   /* At the rtl level, the location to which the runtime will transfer
  86      control.  This differs from the post-landing-pad in that the target's
  87      EXCEPTION_RECEIVER pattern will be expanded here, as well as other
  88      bookkeeping specific to exceptions.  There must not be normal edges
  89      into the block containing the landing-pad label.  */
  90   rtx_code_label *landing_pad;
  91
  92   /* The index of this landing pad within fun->eh->lp_array.  */
  93   int index;
  94 };
  95
  96 /* A catch handler associated with an ERT_TRY region.  */
  97
  98 struct GTY(()) eh_catch_d
  99 {
 100   /* The double-linked list of all catch handlers for the region.  */
 101   struct eh_catch_d *next_catch;
 102   struct eh_catch_d *prev_catch;
 103
 104   /* A TREE_LIST of runtime type objects that this catch handler
 105      will catch, or NULL if all exceptions are caught.  */
 106   tree type_list;
 107
 108   /* A TREE_LIST of INTEGER_CSTs that correspond to the type_list entries,
 109      having been mapped by assign_filter_values.  These integers are to be
 110      compared against the __builtin_eh_filter value.  */
 111   tree filter_list;
 112
 113   /* The code that should be executed if this catch handler matches the
 114      thrown exception.  This label is only maintained until
 115      pass_lower_eh_dispatch, at which point it is cleared.  */
 116   tree label;
 117 };
 118
 119 /* Describes one exception region.  */
 120
 121 struct GTY(()) eh_region_d
 122 {
 123   /* The immediately surrounding region.  */
 124   struct eh_region_d *outer;
 125
 126   /* The list of immediately contained regions.  */
 127   struct eh_region_d *inner;
 128   struct eh_region_d *next_peer;
 129
 130   /* The index of this region within fun->eh->region_array.  */
 131   int index;
 132
 133   /* Each region does exactly one thing.  */
 134   enum eh_region_type type;
 135
 136   /* Holds the action to perform based on the preceding type.  */
 137   union eh_region_u {
 138     struct eh_region_u_try {
 139       /* The double-linked list of all catch handlers for this region.  */
 140       struct eh_catch_d *first_catch;
 141       struct eh_catch_d *last_catch;
 142     } GTY ((tag ("ERT_TRY"))) eh_try;
 143
 144     struct eh_region_u_allowed {
 145       /* A TREE_LIST of runtime type objects allowed to pass.  */
 146       tree type_list;
 147       /* The code that should be executed if the thrown exception does
 148          not match the type list.  This label is only maintained until
 149          pass_lower_eh_dispatch, at which point it is cleared.  */
 150       tree label;
 151       /* The integer that will be passed by the runtime to signal that
 152          we should execute the code at LABEL.  This integer is assigned
 153          by assign_filter_values and is to be compared against the
 154          __builtin_eh_filter value.  */
 155       int filter;
 156     } GTY ((tag ("ERT_ALLOWED_EXCEPTIONS"))) allowed;
 157
 158     struct eh_region_u_must_not_throw {
 159       /* A function decl to be invoked if this region is actually reachable
 160          from within the function, rather than implementable from the runtime.
 161          The normal way for this to happen is for there to be a CLEANUP region
 162          contained within this MUST_NOT_THROW region.  Note that if the
 163          runtime handles the MUST_NOT_THROW region, we have no control over
 164          what termination function is called; it will be decided by the
 165          personality function in effect for this CIE.  */
 166       tree failure_decl;
 167       /* The location assigned to the call of FAILURE_DECL, if expanded.  */
 168       location_t failure_loc;
 169     } GTY ((tag ("ERT_MUST_NOT_THROW"))) must_not_throw;
 170   } GTY ((desc ("%0.type"))) u;
 171
 172   /* The list of landing pads associated with this region.  */
 173   struct eh_landing_pad_d *landing_pads;
 174
 175   /* EXC_PTR and FILTER values copied from the runtime for this region.
 176      Each region gets its own psuedos so that if there are nested exceptions
 177      we do not overwrite the values of the first exception.  */
 178   rtx exc_ptr_reg, filter_reg;
 179
 180   /* True if this region should use __cxa_end_cleanup instead
 181      of _Unwind_Resume.  */
 182   bool use_cxa_end_cleanup;
 183 };
 184
 185 typedef struct eh_landing_pad_d *eh_landing_pad;
 186 typedef struct eh_catch_d *eh_catch;
 187 typedef struct eh_region_d *eh_region;
 188
 189
 190
 191
 192 /* The exception status for each function.  */
 193
 194 struct GTY(()) eh_status
 195 {
 196   /* The tree of all regions for this function.  */
 197   eh_region region_tree;
 198
 199   /* The same information as an indexable array.  */
 200   vec<eh_region, va_gc> *region_array;
 201
 202   /* The landing pads as an indexable array.  */
 203   vec<eh_landing_pad, va_gc> *lp_array;
 204
 205   /* At the gimple level, a mapping from gimple statement to landing pad
 206      or must-not-throw region.  See record_stmt_eh_region.  */
 207   htab_t GTY((param_is (struct throw_stmt_node))) throw_stmt_table;
 208
 209   /* All of the runtime type data used by the function.  These objects
 210      are emitted to the lang-specific-data-area for the function.  */
 211   vec<tree, va_gc> *ttype_data;
 212
 213   /* The table of all action chains.  These encode the eh_region tree in
 214      a compact form for use by the runtime, and is also emitted to the
 215      lang-specific-data-area.  Note that the ARM EABI uses a different
 216      format for the encoding than all other ports.  */
 217   union eh_status_u {
 218     vec<tree, va_gc> *GTY((tag ("1"))) arm_eabi;
 219     vec<uchar, va_gc> *GTY((tag ("0"))) other;
 220   } GTY ((desc ("targetm.arm_eabi_unwinder"))) ehspec_data;
 221 };
 222
 223
 224 /* Invokes CALLBACK for every exception handler label.  Only used by old
 225    loop hackery; should not be used by new code.  */
 226 extern void for_each_eh_label (void (*) (rtx));
 227
 228 extern void init_eh_for_function (void);
 229
 230 extern void remove_eh_landing_pad (eh_landing_pad);
 231 extern void remove_eh_handler (eh_region);
 232 extern void remove_unreachable_eh_regions (sbitmap);
 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 hash_map<void *, void *> *duplicate_eh_regions
 253   (struct function *, eh_region, int, duplicate_eh_regions_map, void *);
 254
 255 extern void sjlj_emit_function_exit_after (rtx_insn *);
 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)