gcc/except.h

   1 /* Exception Handling interface routines.
   2    Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
   3    2007, 2008  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 #include "sbitmap.h"
  23 #include "vecprim.h"
  24
  25 struct function;
  26
  27 /* Describes one exception region.  */
  28 struct GTY(()) eh_region
  29 {
  30   /* The immediately surrounding region.  */
  31   struct eh_region *outer;
  32
  33   /* The list of immediately contained regions.  */
  34   struct eh_region *inner;
  35   struct eh_region *next_peer;
  36
  37   /* List of regions sharing label.  */
  38   struct eh_region *next_region_sharing_label;
  39
  40   /* An identifier for this region.  */
  41   int region_number;
  42
  43   /* When a region is deleted, its parents inherit the REG_EH_REGION
  44      numbers already assigned.  */
  45   bitmap aka;
  46
  47   /* Each region does exactly one thing.  */
  48   enum eh_region_type
  49   {
  50     ERT_UNKNOWN = 0,
  51     ERT_CLEANUP,
  52     ERT_TRY,
  53     ERT_CATCH,
  54     ERT_ALLOWED_EXCEPTIONS,
  55     ERT_MUST_NOT_THROW,
  56     ERT_THROW
  57   } type;
  58
  59   /* Holds the action to perform based on the preceding type.  */
  60   union eh_region_u {
  61     /* A list of catch blocks, a surrounding try block,
  62        and the label for continuing after a catch.  */
  63     struct eh_region_u_try {
  64       struct eh_region *eh_catch;
  65       struct eh_region *last_catch;
  66     } GTY ((tag ("ERT_TRY"))) eh_try;
  67
  68     /* The list through the catch handlers, the list of type objects
  69        matched, and the list of associated filters.  */
  70     struct eh_region_u_catch {
  71       struct eh_region *next_catch;
  72       struct eh_region *prev_catch;
  73       tree type_list;
  74       tree filter_list;
  75     } GTY ((tag ("ERT_CATCH"))) eh_catch;
  76
  77     /* A tree_list of allowed types.  */
  78     struct eh_region_u_allowed {
  79       tree type_list;
  80       int filter;
  81     } GTY ((tag ("ERT_ALLOWED_EXCEPTIONS"))) allowed;
  82
  83     /* The type given by a call to "throw foo();", or discovered
  84        for a throw.  */
  85     struct eh_region_u_throw {
  86       tree type;
  87     } GTY ((tag ("ERT_THROW"))) eh_throw;
  88
  89     /* Retain the cleanup expression even after expansion so that
  90        we can match up fixup regions.  */
  91     struct eh_region_u_cleanup {
  92       struct eh_region *prev_try;
  93     } GTY ((tag ("ERT_CLEANUP"))) cleanup;
  94   } GTY ((desc ("%0.type"))) u;
  95
  96   /* Entry point for this region's handler before landing pads are built.  */
  97   rtx label;
  98   tree tree_label;
  99
 100   /* Entry point for this region's handler from the runtime eh library.  */
 101   rtx landing_pad;
 102
 103   /* Entry point for this region's handler from an inner region.  */
 104   rtx post_landing_pad;
 105
 106   /* The RESX insn for handing off control to the next outermost handler,
 107      if appropriate.  */
 108   rtx resume;
 109
 110   /* True if something in this region may throw.  */
 111   unsigned may_contain_throw : 1;
 112 };
 113
 114 typedef struct eh_region *eh_region;
 115 DEF_VEC_P(eh_region);
 116 DEF_VEC_ALLOC_P(eh_region, gc);
 117 DEF_VEC_ALLOC_P(eh_region, heap);
 118
 119 /* Per-function EH data.  Used to save exception status for each
 120    function.  */
 121 struct GTY(()) eh_status
 122 {
 123   /* The tree of all regions for this function.  */
 124   struct eh_region *region_tree;
 125
 126   /* The same information as an indexable array.  */
 127   VEC(eh_region,gc) *region_array;
 128   int last_region_number;
 129
 130   htab_t GTY((param_is (struct throw_stmt_node))) throw_stmt_table;
 131 };
 132
 133
 134 /* Test: is exception handling turned on?  */
 135 extern int doing_eh (int);
 136
 137 /* Note that the current EH region (if any) may contain a throw, or a
 138    call to a function which itself may contain a throw.  */
 139 extern void note_eh_region_may_contain_throw (struct eh_region *);
 140
 141 /* Invokes CALLBACK for every exception handler label.  Only used by old
 142    loop hackery; should not be used by new code.  */
 143 extern void for_each_eh_label (void (*) (rtx));
 144
 145 /* Invokes CALLBACK for every exception region in the current function.  */
 146 extern void for_each_eh_region (void (*) (struct eh_region *));
 147
 148 /* Determine if the given INSN can throw an exception.  */
 149 extern bool can_throw_internal_1 (int, bool, bool);
 150 extern bool can_throw_internal (const_rtx);
 151 extern bool can_throw_external_1 (int, bool, bool);
 152 extern bool can_throw_external (const_rtx);
 153
 154 /* Set TREE_NOTHROW and cfun->all_throwers_are_sibcalls.  */
 155 extern unsigned int set_nothrow_function_flags (void);
 156
 157 extern void init_eh (void);
 158 extern void init_eh_for_function (void);
 159
 160 extern rtx reachable_handlers (rtx);
 161 extern void remove_eh_region (int);
 162 extern void remove_eh_region_and_replace_by_outer_of (int, int);
 163
 164 extern void convert_from_eh_region_ranges (void);
 165 extern unsigned int convert_to_eh_region_ranges (void);
 166 extern void find_exception_handler_labels (void);
 167 extern bool current_function_has_exception_handlers (void);
 168 extern void output_function_exception_table (const char *);
 169
 170 extern void expand_builtin_unwind_init (void);
 171 extern rtx expand_builtin_eh_return_data_regno (tree);
 172 extern rtx expand_builtin_extract_return_addr (tree);
 173 extern void expand_builtin_init_dwarf_reg_sizes (tree);
 174 extern rtx expand_builtin_frob_return_addr (tree);
 175 extern rtx expand_builtin_dwarf_sp_column (void);
 176 extern void expand_builtin_eh_return (tree, tree);
 177 extern void expand_eh_return (void);
 178 extern rtx expand_builtin_extend_pointer (tree);
 179 extern rtx get_exception_pointer (void);
 180 extern rtx get_exception_filter (void);
 181 typedef tree (*duplicate_eh_regions_map) (tree, void *);
 182 extern int duplicate_eh_regions (struct function *, duplicate_eh_regions_map,
 183                                  void *, int, int);
 184
 185 extern void sjlj_emit_function_exit_after (rtx);
 186 extern void default_init_unwind_resume_libfunc (void);
 187
 188 extern struct eh_region *gen_eh_region_cleanup (struct eh_region *,
 189                                                 struct eh_region *);
 190 extern struct eh_region *gen_eh_region_try (struct eh_region *);
 191 extern struct eh_region *gen_eh_region_catch (struct eh_region *, tree);
 192 extern struct eh_region *gen_eh_region_allowed (struct eh_region *, tree);
 193 extern struct eh_region *gen_eh_region_must_not_throw (struct eh_region *);
 194 extern int get_eh_region_number (struct eh_region *);
 195 extern bool get_eh_region_may_contain_throw (struct eh_region *);
 196 extern tree get_eh_region_no_tree_label (int);
 197 extern tree get_eh_region_tree_label (struct eh_region *);
 198 extern void set_eh_region_tree_label (struct eh_region *, tree);
 199
 200 extern void foreach_reachable_handler (int, bool, bool,
 201                                        void (*) (struct eh_region *, void *),
 202                                        void *);
 203
 204 extern void collect_eh_region_array (void);
 205 extern void expand_resx_expr (tree);
 206 extern void verify_eh_tree (struct function *);
 207 extern void dump_eh_tree (FILE *, struct function *);
 208 void debug_eh_tree (struct function *);
 209 extern int eh_region_outermost (struct function *, int, int);
 210 extern void add_type_for_runtime (tree);
 211 extern tree lookup_type_for_runtime (tree);
 212
 213 /* If non-NULL, this is a function that returns an expression to be
 214    executed if an unhandled exception is propagated out of a cleanup
 215    region.  For example, in C++, an exception thrown by a destructor
 216    during stack unwinding is required to result in a call to
 217    `std::terminate', so the C++ version of this function returns a
 218    CALL_EXPR for `std::terminate'.  */
 219 extern gimple (*lang_protect_cleanup_actions) (void);
 220
 221 /* Return true if type A catches type B.  */
 222 extern int (*lang_eh_type_covers) (tree a, tree b);
 223
 224 /* Map a type to a runtime object to match type.  */
 225 extern tree (*lang_eh_runtime_type) (tree);
 226
 227
 228 /* Just because the user configured --with-sjlj-exceptions=no doesn't
 229    mean that we can use call frame exceptions.  Detect that the target
 230    has appropriate support.  */
 231
 232 #ifndef MUST_USE_SJLJ_EXCEPTIONS
 233 # if defined (EH_RETURN_DATA_REGNO)                     \
 234        && (defined (TARGET_UNWIND_INFO)                 \
 235            || (DWARF2_UNWIND_INFO                       \
 236                && (defined (EH_RETURN_HANDLER_RTX)      \
 237                    || defined (HAVE_eh_return))))
 238 #  define MUST_USE_SJLJ_EXCEPTIONS      0
 239 # else
 240 #  define MUST_USE_SJLJ_EXCEPTIONS      1
 241 # endif
 242 #endif
 243
 244 #ifdef CONFIG_SJLJ_EXCEPTIONS
 245 # if CONFIG_SJLJ_EXCEPTIONS == 1
 246 #  define USING_SJLJ_EXCEPTIONS         1
 247 # endif
 248 # if CONFIG_SJLJ_EXCEPTIONS == 0
 249 #  define USING_SJLJ_EXCEPTIONS         0
 250 #  if !defined(EH_RETURN_DATA_REGNO)
 251     #error "EH_RETURN_DATA_REGNO required"
 252 #  endif
 253 #  if ! (defined(TARGET_UNWIND_INFO) || DWARF2_UNWIND_INFO)
 254     #error "{DWARF2,TARGET}_UNWIND_INFO required"
 255 #  endif
 256 #  if !defined(TARGET_UNWIND_INFO) \
 257         && !(defined(EH_RETURN_HANDLER_RTX) || defined(HAVE_eh_return))
 258     #error "EH_RETURN_HANDLER_RTX or eh_return required"
 259 #  endif
 260 /* Usually the above error checks will have already triggered an
 261    error, but backends may set MUST_USE_SJLJ_EXCEPTIONS for their own
 262    reasons.  */
 263 #  if MUST_USE_SJLJ_EXCEPTIONS
 264     #error "Must use SJLJ exceptions but configured not to"
 265 #  endif
 266 # endif
 267 #else
 268 # define USING_SJLJ_EXCEPTIONS          MUST_USE_SJLJ_EXCEPTIONS
 269 #endif
 270
 271 struct GTY(()) throw_stmt_node {
 272   gimple stmt;
 273   int region_nr;
 274 };
 275
 276 extern struct htab *get_eh_throw_stmt_table (struct function *);
 277 extern void set_eh_throw_stmt_table (struct function *, struct htab *);
 278 extern void remove_unreachable_regions (sbitmap, sbitmap);
 279 extern VEC(int,heap) * label_to_region_map (void);
 280 extern int num_eh_regions (void);
 281 extern struct eh_region *redirect_eh_edge_to_label (struct edge_def *, tree, bool, bool, int);
 282 extern int get_next_region_sharing_label (int);