1/* Exception Handling interface routines. 2 Copyright (C) 1996-2015 Free Software Foundation, Inc. 3 Contributed by Mike Stump <mrs@cygnus.com>. 4 5This file is part of GCC. 6 7GCC is free software; you can redistribute it and/or modify it under 8the terms of the GNU General Public License as published by the Free 9Software Foundation; either version 3, or (at your option) any later 10version. 11 12GCC is distributed in the hope that it will be useful, but WITHOUT ANY 13WARRANTY; without even the implied warranty of MERCHANTABILITY or 14FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15for more details. 16 17You should have received a copy of the GNU General Public License 18along 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 27#include "hash-map.h" 28#include "hashtab.h" 29 30struct function; 31struct eh_region_d; 32 33/* The type of an exception region. */ 34enum eh_region_type 35{ 36 /* CLEANUP regions implement e.g. destructors run when exiting a block. 37 They can be generated from both GIMPLE_TRY_FINALLY and GIMPLE_TRY_CATCH 38 nodes. It is expected by the runtime that cleanup regions will *not* 39 resume normal program flow, but will continue propagation of the 40 exception. */ 41 ERT_CLEANUP, 42 43 /* TRY regions implement catching an exception. The list of types associated 44 with the attached catch handlers is examined in order by the runtime and 45 control is transferred to the appropriate handler. Note that a NULL type 46 list is a catch-all handler, and that it will catch *all* exceptions 47 including those originating from a different language. */ 48 ERT_TRY, 49 50 /* ALLOWED_EXCEPTIONS regions implement exception filtering, e.g. the 51 throw(type-list) specification that can be added to C++ functions. 52 The runtime examines the thrown exception vs the type list, and if 53 the exception does not match, transfers control to the handler. The 54 normal handler for C++ calls __cxa_call_unexpected. */ 55 ERT_ALLOWED_EXCEPTIONS, 56 57 /* MUST_NOT_THROW regions prevent all exceptions from propagating. This 58 region type is used in C++ to surround destructors being run inside a 59 CLEANUP region. This differs from an ALLOWED_EXCEPTIONS region with 60 an empty type list in that the runtime is prepared to terminate the 61 program directly. We only generate code for MUST_NOT_THROW regions 62 along control paths that are already handling an exception within the 63 current function. */ 64 ERT_MUST_NOT_THROW 65}; 66 67 68/* A landing pad for a given exception region. Any transfer of control 69 from the EH runtime to the function happens at a landing pad. */ 70 71struct GTY(()) eh_landing_pad_d 72{ 73 /* The linked list of all landing pads associated with the region. */ 74 struct eh_landing_pad_d *next_lp; 75 76 /* The region with which this landing pad is associated. */ 77 struct eh_region_d *region; 78 79 /* At the gimple level, the location to which control will be transferred 80 for this landing pad. There can be both EH and normal edges into the 81 block containing the post-landing-pad label. */ 82 tree post_landing_pad; 83 84 /* At the rtl level, the location to which the runtime will transfer 85 control. This differs from the post-landing-pad in that the target's 86 EXCEPTION_RECEIVER pattern will be expanded here, as well as other 87 bookkeeping specific to exceptions. There must not be normal edges 88 into the block containing the landing-pad label. */ 89 rtx_code_label *landing_pad; 90 91 /* The index of this landing pad within fun->eh->lp_array. */ 92 int index; 93}; 94 95/* A catch handler associated with an ERT_TRY region. */ 96 97struct GTY(()) eh_catch_d 98{ 99 /* The double-linked list of all catch handlers for the region. */ 100 struct eh_catch_d *next_catch; 101 struct eh_catch_d *prev_catch; 102 103 /* A TREE_LIST of runtime type objects that this catch handler 104 will catch, or NULL if all exceptions are caught. */ 105 tree type_list; 106 107 /* A TREE_LIST of INTEGER_CSTs that correspond to the type_list entries, 108 having been mapped by assign_filter_values. These integers are to be 109 compared against the __builtin_eh_filter value. */ 110 tree filter_list; 111 112 /* The code that should be executed if this catch handler matches the 113 thrown exception. This label is only maintained until 114 pass_lower_eh_dispatch, at which point it is cleared. */ 115 tree label; 116}; 117 118/* Describes one exception region. */ 119 120struct GTY(()) eh_region_d 121{ 122 /* The immediately surrounding region. */ 123 struct eh_region_d *outer; 124 125 /* The list of immediately contained regions. */ 126 struct eh_region_d *inner; 127 struct eh_region_d *next_peer; 128 129 /* The index of this region within fun->eh->region_array. */ 130 int index; 131 132 /* Each region does exactly one thing. */ 133 enum eh_region_type type; 134 135 /* Holds the action to perform based on the preceding type. */ 136 union eh_region_u { 137 struct eh_region_u_try { 138 /* The double-linked list of all catch handlers for this region. */ 139 struct eh_catch_d *first_catch; 140 struct eh_catch_d *last_catch; 141 } GTY ((tag ("ERT_TRY"))) eh_try; 142 143 struct eh_region_u_allowed { 144 /* A TREE_LIST of runtime type objects allowed to pass. */ 145 tree type_list; 146 /* The code that should be executed if the thrown exception does 147 not match the type list. This label is only maintained until 148 pass_lower_eh_dispatch, at which point it is cleared. */ 149 tree label; 150 /* The integer that will be passed by the runtime to signal that 151 we should execute the code at LABEL. This integer is assigned 152 by assign_filter_values and is to be compared against the 153 __builtin_eh_filter value. */ 154 int filter; 155 } GTY ((tag ("ERT_ALLOWED_EXCEPTIONS"))) allowed; 156 157 struct eh_region_u_must_not_throw { 158 /* A function decl to be invoked if this region is actually reachable 159 from within the function, rather than implementable from the runtime. 160 The normal way for this to happen is for there to be a CLEANUP region 161 contained within this MUST_NOT_THROW region. Note that if the 162 runtime handles the MUST_NOT_THROW region, we have no control over 163 what termination function is called; it will be decided by the 164 personality function in effect for this CIE. */ 165 tree failure_decl; 166 /* The location assigned to the call of FAILURE_DECL, if expanded. */ 167 location_t failure_loc; 168 } GTY ((tag ("ERT_MUST_NOT_THROW"))) must_not_throw; 169 } GTY ((desc ("%0.type"))) u; 170 171 /* The list of landing pads associated with this region. */ 172 struct eh_landing_pad_d *landing_pads; 173 174 /* EXC_PTR and FILTER values copied from the runtime for this region. 175 Each region gets its own psuedos so that if there are nested exceptions 176 we do not overwrite the values of the first exception. */ 177 rtx exc_ptr_reg, filter_reg; 178 179 /* True if this region should use __cxa_end_cleanup instead 180 of _Unwind_Resume. */ 181 bool use_cxa_end_cleanup; 182}; 183 184typedef struct eh_landing_pad_d *eh_landing_pad; 185typedef struct eh_catch_d *eh_catch; 186typedef struct eh_region_d *eh_region; 187 188 189 190 191/* The exception status for each function. */ 192 193struct GTY(()) eh_status 194{ 195 /* The tree of all regions for this function. */ 196 eh_region region_tree; 197 198 /* The same information as an indexable array. */ 199 vec<eh_region, va_gc> *region_array; 200 201 /* The landing pads as an indexable array. */ 202 vec<eh_landing_pad, va_gc> *lp_array; 203 204 /* At the gimple level, a mapping from gimple statement to landing pad 205 or must-not-throw region. See record_stmt_eh_region. */ 206 hash_map<gimple, int> *GTY(()) throw_stmt_table; 207 208 /* All of the runtime type data used by the function. These objects 209 are emitted to the lang-specific-data-area for the function. */ 210 vec<tree, va_gc> *ttype_data; 211 212 /* The table of all action chains. These encode the eh_region tree in 213 a compact form for use by the runtime, and is also emitted to the 214 lang-specific-data-area. Note that the ARM EABI uses a different 215 format for the encoding than all other ports. */ 216 union eh_status_u { 217 vec<tree, va_gc> *GTY((tag ("1"))) arm_eabi; 218 vec<uchar, va_gc> *GTY((tag ("0"))) other; 219 } GTY ((desc ("targetm.arm_eabi_unwinder"))) ehspec_data; 220}; 221 222 223/* Invokes CALLBACK for every exception handler label. Only used by old 224 loop hackery; should not be used by new code. */ 225extern void for_each_eh_label (void (*) (rtx)); 226 227extern void init_eh_for_function (void); 228 229extern void remove_eh_landing_pad (eh_landing_pad); 230extern void remove_eh_handler (eh_region); 231extern void remove_unreachable_eh_regions (sbitmap); 232 233extern bool current_function_has_exception_handlers (void); 234extern void output_function_exception_table (const char *); 235 236extern rtx expand_builtin_eh_pointer (tree); 237extern rtx expand_builtin_eh_filter (tree); 238extern rtx expand_builtin_eh_copy_values (tree); 239extern void expand_builtin_unwind_init (void); 240extern rtx expand_builtin_eh_return_data_regno (tree); 241extern rtx expand_builtin_extract_return_addr (tree); 242extern void expand_builtin_init_dwarf_reg_sizes (tree); 243extern rtx expand_builtin_frob_return_addr (tree); 244extern rtx expand_builtin_dwarf_sp_column (void); 245extern void expand_builtin_eh_return (tree, tree); 246extern void expand_eh_return (void); 247extern rtx expand_builtin_extend_pointer (tree); 248extern void expand_dw2_landing_pad_for_region (eh_region); 249 250typedef tree (*duplicate_eh_regions_map) (tree, void *); 251extern hash_map<void *, void *> *duplicate_eh_regions 252 (struct function *, eh_region, int, duplicate_eh_regions_map, void *); 253 254extern void sjlj_emit_function_exit_after (rtx_insn *); 255 256extern eh_region gen_eh_region_cleanup (eh_region); 257extern eh_region gen_eh_region_try (eh_region); 258extern eh_region gen_eh_region_allowed (eh_region, tree); 259extern eh_region gen_eh_region_must_not_throw (eh_region); 260 261extern eh_catch gen_eh_region_catch (eh_region, tree); 262extern eh_landing_pad gen_eh_landing_pad (eh_region); 263 264extern eh_region get_eh_region_from_number_fn (struct function *, int); 265extern eh_region get_eh_region_from_number (int); 266extern eh_landing_pad get_eh_landing_pad_from_number_fn (struct function*,int); 267extern eh_landing_pad get_eh_landing_pad_from_number (int); 268extern eh_region get_eh_region_from_lp_number_fn (struct function *, int); 269extern eh_region get_eh_region_from_lp_number (int); 270 271extern eh_region eh_region_outermost (struct function *, eh_region, eh_region); 272 273extern void make_reg_eh_region_note (rtx insn, int ecf_flags, int lp_nr); 274extern void make_reg_eh_region_note_nothrow_nononlocal (rtx); 275 276extern void verify_eh_tree (struct function *); 277extern void dump_eh_tree (FILE *, struct function *); 278void debug_eh_tree (struct function *); 279extern void add_type_for_runtime (tree); 280extern tree lookup_type_for_runtime (tree); 281extern void assign_filter_values (void); 282 283extern eh_region get_eh_region_from_rtx (const_rtx); 284extern eh_landing_pad get_eh_landing_pad_from_rtx (const_rtx); 285 286extern void finish_eh_generation (void); 287 288struct GTY(()) throw_stmt_node { 289 gimple stmt; 290 int lp_nr; 291}; 292 293extern hash_map<gimple, int> *get_eh_throw_stmt_table (struct function *); 294extern void set_eh_throw_stmt_table (function *, hash_map<gimple, int> *); 295 296enum eh_personality_kind { 297 eh_personality_none, 298 eh_personality_any, 299 eh_personality_lang 300}; 301 302extern enum eh_personality_kind 303function_needs_eh_personality (struct function *); 304 305/* Pre-order iteration within the eh_region tree. */ 306 307static inline eh_region 308ehr_next (eh_region r, eh_region start) 309{ 310 if (r->inner) 311 r = r->inner; 312 else if (r->next_peer && r != start) 313 r = r->next_peer; 314 else 315 { 316 do 317 { 318 r = r->outer; 319 if (r == start) 320 return NULL; 321 } 322 while (r->next_peer == NULL); 323 r = r->next_peer; 324 } 325 return r; 326} 327 328#define FOR_ALL_EH_REGION_AT(R, START) \ 329 for ((R) = (START); (R) != NULL; (R) = ehr_next (R, START)) 330 331#define FOR_ALL_EH_REGION_FN(R, FN) \ 332 for ((R) = (FN)->eh->region_tree; (R) != NULL; (R) = ehr_next (R, NULL)) 333 334#define FOR_ALL_EH_REGION(R) FOR_ALL_EH_REGION_FN (R, cfun) 335 336#endif 337