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