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 "hashtab.h"
29
30 struct function;
31 struct eh_region_d;
32 struct pointer_map_t;
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 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 struct pointer_map_t *duplicate_eh_regions
253 (struct function *, eh_region, int, duplicate_eh_regions_map, void *);
254
255 extern void sjlj_emit_function_exit_after (rtx);
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
ehr_next(eh_region r,eh_region start)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)
336