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12670d88 | 1 | /* Implements exception handling. |
e5e809f4 | 2 | Copyright (C) 1989, 92-97, 1998 Free Software Foundation, Inc. |
4956d07c MS |
3 | Contributed by Mike Stump <mrs@cygnus.com>. |
4 | ||
5 | This file is part of GNU CC. | |
6 | ||
7 | GNU CC is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2, or (at your option) | |
10 | any later version. | |
11 | ||
12 | GNU CC is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GNU CC; see the file COPYING. If not, write to | |
19 | the Free Software Foundation, 59 Temple Place - Suite 330, | |
20 | Boston, MA 02111-1307, USA. */ | |
21 | ||
22 | ||
12670d88 RK |
23 | /* An exception is an event that can be signaled from within a |
24 | function. This event can then be "caught" or "trapped" by the | |
25 | callers of this function. This potentially allows program flow to | |
956d6950 | 26 | be transferred to any arbitrary code associated with a function call |
12670d88 RK |
27 | several levels up the stack. |
28 | ||
29 | The intended use for this mechanism is for signaling "exceptional | |
30 | events" in an out-of-band fashion, hence its name. The C++ language | |
31 | (and many other OO-styled or functional languages) practically | |
32 | requires such a mechanism, as otherwise it becomes very difficult | |
33 | or even impossible to signal failure conditions in complex | |
34 | situations. The traditional C++ example is when an error occurs in | |
35 | the process of constructing an object; without such a mechanism, it | |
36 | is impossible to signal that the error occurs without adding global | |
37 | state variables and error checks around every object construction. | |
38 | ||
39 | The act of causing this event to occur is referred to as "throwing | |
40 | an exception". (Alternate terms include "raising an exception" or | |
41 | "signaling an exception".) The term "throw" is used because control | |
42 | is returned to the callers of the function that is signaling the | |
43 | exception, and thus there is the concept of "throwing" the | |
44 | exception up the call stack. | |
45 | ||
27a36778 MS |
46 | There are two major codegen options for exception handling. The |
47 | flag -fsjlj-exceptions can be used to select the setjmp/longjmp | |
e9a25f70 | 48 | approach, which is the default. -fno-sjlj-exceptions can be used to |
27a36778 MS |
49 | get the PC range table approach. While this is a compile time |
50 | flag, an entire application must be compiled with the same codegen | |
51 | option. The first is a PC range table approach, the second is a | |
52 | setjmp/longjmp based scheme. We will first discuss the PC range | |
53 | table approach, after that, we will discuss the setjmp/longjmp | |
54 | based approach. | |
55 | ||
12670d88 RK |
56 | It is appropriate to speak of the "context of a throw". This |
57 | context refers to the address where the exception is thrown from, | |
58 | and is used to determine which exception region will handle the | |
59 | exception. | |
60 | ||
61 | Regions of code within a function can be marked such that if it | |
62 | contains the context of a throw, control will be passed to a | |
63 | designated "exception handler". These areas are known as "exception | |
64 | regions". Exception regions cannot overlap, but they can be nested | |
65 | to any arbitrary depth. Also, exception regions cannot cross | |
66 | function boundaries. | |
67 | ||
2ed18e63 MS |
68 | Exception handlers can either be specified by the user (which we |
69 | will call a "user-defined handler") or generated by the compiler | |
70 | (which we will designate as a "cleanup"). Cleanups are used to | |
71 | perform tasks such as destruction of objects allocated on the | |
72 | stack. | |
73 | ||
956d6950 | 74 | In the current implementation, cleanups are handled by allocating an |
2ed18e63 MS |
75 | exception region for the area that the cleanup is designated for, |
76 | and the handler for the region performs the cleanup and then | |
77 | rethrows the exception to the outer exception region. From the | |
78 | standpoint of the current implementation, there is little | |
79 | distinction made between a cleanup and a user-defined handler, and | |
80 | the phrase "exception handler" can be used to refer to either one | |
81 | equally well. (The section "Future Directions" below discusses how | |
82 | this will change). | |
83 | ||
84 | Each object file that is compiled with exception handling contains | |
85 | a static array of exception handlers named __EXCEPTION_TABLE__. | |
86 | Each entry contains the starting and ending addresses of the | |
87 | exception region, and the address of the handler designated for | |
88 | that region. | |
12670d88 | 89 | |
ca55abae JM |
90 | If the target does not use the DWARF 2 frame unwind information, at |
91 | program startup each object file invokes a function named | |
12670d88 | 92 | __register_exceptions with the address of its local |
ca55abae JM |
93 | __EXCEPTION_TABLE__. __register_exceptions is defined in libgcc2.c, and |
94 | is responsible for recording all of the exception regions into one list | |
95 | (which is kept in a static variable named exception_table_list). | |
96 | ||
97 | On targets that support crtstuff.c, the unwind information | |
98 | is stored in a section named .eh_frame and the information for the | |
99 | entire shared object or program is registered with a call to | |
6d8ccdbb | 100 | __register_frame_info. On other targets, the information for each |
d1485032 | 101 | translation unit is registered from the file generated by collect2. |
6d8ccdbb | 102 | __register_frame_info is defined in frame.c, and is responsible for |
ca55abae JM |
103 | recording all of the unwind regions into one list (which is kept in a |
104 | static variable named unwind_table_list). | |
12670d88 | 105 | |
27a36778 | 106 | The function __throw is actually responsible for doing the |
ca55abae JM |
107 | throw. On machines that have unwind info support, __throw is generated |
108 | by code in libgcc2.c, otherwise __throw is generated on a | |
12670d88 | 109 | per-object-file basis for each source file compiled with |
38e01259 | 110 | -fexceptions by the C++ frontend. Before __throw is invoked, |
ca55abae JM |
111 | the current context of the throw needs to be placed in the global |
112 | variable __eh_pc. | |
12670d88 | 113 | |
27a36778 | 114 | __throw attempts to find the appropriate exception handler for the |
12670d88 | 115 | PC value stored in __eh_pc by calling __find_first_exception_table_match |
2ed18e63 | 116 | (which is defined in libgcc2.c). If __find_first_exception_table_match |
ca55abae JM |
117 | finds a relevant handler, __throw transfers control directly to it. |
118 | ||
119 | If a handler for the context being thrown from can't be found, __throw | |
120 | walks (see Walking the stack below) the stack up the dynamic call chain to | |
121 | continue searching for an appropriate exception handler based upon the | |
122 | caller of the function it last sought a exception handler for. It stops | |
123 | then either an exception handler is found, or when the top of the | |
124 | call chain is reached. | |
125 | ||
126 | If no handler is found, an external library function named | |
127 | __terminate is called. If a handler is found, then we restart | |
128 | our search for a handler at the end of the call chain, and repeat | |
129 | the search process, but instead of just walking up the call chain, | |
130 | we unwind the call chain as we walk up it. | |
12670d88 RK |
131 | |
132 | Internal implementation details: | |
133 | ||
12670d88 | 134 | To associate a user-defined handler with a block of statements, the |
27a36778 | 135 | function expand_start_try_stmts is used to mark the start of the |
12670d88 | 136 | block of statements with which the handler is to be associated |
2ed18e63 MS |
137 | (which is known as a "try block"). All statements that appear |
138 | afterwards will be associated with the try block. | |
139 | ||
27a36778 | 140 | A call to expand_start_all_catch marks the end of the try block, |
2ed18e63 MS |
141 | and also marks the start of the "catch block" (the user-defined |
142 | handler) associated with the try block. | |
143 | ||
144 | This user-defined handler will be invoked for *every* exception | |
145 | thrown with the context of the try block. It is up to the handler | |
146 | to decide whether or not it wishes to handle any given exception, | |
147 | as there is currently no mechanism in this implementation for doing | |
148 | this. (There are plans for conditionally processing an exception | |
149 | based on its "type", which will provide a language-independent | |
150 | mechanism). | |
151 | ||
152 | If the handler chooses not to process the exception (perhaps by | |
153 | looking at an "exception type" or some other additional data | |
154 | supplied with the exception), it can fall through to the end of the | |
27a36778 | 155 | handler. expand_end_all_catch and expand_leftover_cleanups |
2ed18e63 MS |
156 | add additional code to the end of each handler to take care of |
157 | rethrowing to the outer exception handler. | |
158 | ||
159 | The handler also has the option to continue with "normal flow of | |
160 | code", or in other words to resume executing at the statement | |
161 | immediately after the end of the exception region. The variable | |
162 | caught_return_label_stack contains a stack of labels, and jumping | |
27a36778 | 163 | to the topmost entry's label via expand_goto will resume normal |
2ed18e63 MS |
164 | flow to the statement immediately after the end of the exception |
165 | region. If the handler falls through to the end, the exception will | |
166 | be rethrown to the outer exception region. | |
167 | ||
168 | The instructions for the catch block are kept as a separate | |
169 | sequence, and will be emitted at the end of the function along with | |
27a36778 MS |
170 | the handlers specified via expand_eh_region_end. The end of the |
171 | catch block is marked with expand_end_all_catch. | |
12670d88 RK |
172 | |
173 | Any data associated with the exception must currently be handled by | |
174 | some external mechanism maintained in the frontend. For example, | |
175 | the C++ exception mechanism passes an arbitrary value along with | |
176 | the exception, and this is handled in the C++ frontend by using a | |
2ed18e63 MS |
177 | global variable to hold the value. (This will be changing in the |
178 | future.) | |
179 | ||
180 | The mechanism in C++ for handling data associated with the | |
181 | exception is clearly not thread-safe. For a thread-based | |
182 | environment, another mechanism must be used (possibly using a | |
183 | per-thread allocation mechanism if the size of the area that needs | |
184 | to be allocated isn't known at compile time.) | |
185 | ||
186 | Internally-generated exception regions (cleanups) are marked by | |
27a36778 | 187 | calling expand_eh_region_start to mark the start of the region, |
2ed18e63 MS |
188 | and expand_eh_region_end (handler) is used to both designate the |
189 | end of the region and to associate a specified handler/cleanup with | |
190 | the region. The rtl code in HANDLER will be invoked whenever an | |
191 | exception occurs in the region between the calls to | |
192 | expand_eh_region_start and expand_eh_region_end. After HANDLER is | |
193 | executed, additional code is emitted to handle rethrowing the | |
194 | exception to the outer exception handler. The code for HANDLER will | |
195 | be emitted at the end of the function. | |
12670d88 RK |
196 | |
197 | TARGET_EXPRs can also be used to designate exception regions. A | |
198 | TARGET_EXPR gives an unwind-protect style interface commonly used | |
199 | in functional languages such as LISP. The associated expression is | |
2ed18e63 MS |
200 | evaluated, and whether or not it (or any of the functions that it |
201 | calls) throws an exception, the protect expression is always | |
202 | invoked. This implementation takes care of the details of | |
203 | associating an exception table entry with the expression and | |
204 | generating the necessary code (it actually emits the protect | |
205 | expression twice, once for normal flow and once for the exception | |
206 | case). As for the other handlers, the code for the exception case | |
207 | will be emitted at the end of the function. | |
208 | ||
209 | Cleanups can also be specified by using add_partial_entry (handler) | |
27a36778 | 210 | and end_protect_partials. add_partial_entry creates the start of |
2ed18e63 MS |
211 | a new exception region; HANDLER will be invoked if an exception is |
212 | thrown with the context of the region between the calls to | |
213 | add_partial_entry and end_protect_partials. end_protect_partials is | |
214 | used to mark the end of these regions. add_partial_entry can be | |
215 | called as many times as needed before calling end_protect_partials. | |
216 | However, end_protect_partials should only be invoked once for each | |
27a36778 | 217 | group of calls to add_partial_entry as the entries are queued |
2ed18e63 MS |
218 | and all of the outstanding entries are processed simultaneously |
219 | when end_protect_partials is invoked. Similarly to the other | |
220 | handlers, the code for HANDLER will be emitted at the end of the | |
221 | function. | |
12670d88 RK |
222 | |
223 | The generated RTL for an exception region includes | |
224 | NOTE_INSN_EH_REGION_BEG and NOTE_INSN_EH_REGION_END notes that mark | |
225 | the start and end of the exception region. A unique label is also | |
2ed18e63 MS |
226 | generated at the start of the exception region, which is available |
227 | by looking at the ehstack variable. The topmost entry corresponds | |
228 | to the current region. | |
12670d88 RK |
229 | |
230 | In the current implementation, an exception can only be thrown from | |
231 | a function call (since the mechanism used to actually throw an | |
232 | exception involves calling __throw). If an exception region is | |
233 | created but no function calls occur within that region, the region | |
2ed18e63 | 234 | can be safely optimized away (along with its exception handlers) |
27a36778 MS |
235 | since no exceptions can ever be caught in that region. This |
236 | optimization is performed unless -fasynchronous-exceptions is | |
237 | given. If the user wishes to throw from a signal handler, or other | |
238 | asynchronous place, -fasynchronous-exceptions should be used when | |
239 | compiling for maximally correct code, at the cost of additional | |
240 | exception regions. Using -fasynchronous-exceptions only produces | |
241 | code that is reasonably safe in such situations, but a correct | |
242 | program cannot rely upon this working. It can be used in failsafe | |
243 | code, where trying to continue on, and proceeding with potentially | |
244 | incorrect results is better than halting the program. | |
245 | ||
12670d88 | 246 | |
ca55abae | 247 | Walking the stack: |
12670d88 | 248 | |
ca55abae JM |
249 | The stack is walked by starting with a pointer to the current |
250 | frame, and finding the pointer to the callers frame. The unwind info | |
251 | tells __throw how to find it. | |
12670d88 | 252 | |
ca55abae | 253 | Unwinding the stack: |
12670d88 | 254 | |
ca55abae JM |
255 | When we use the term unwinding the stack, we mean undoing the |
256 | effects of the function prologue in a controlled fashion so that we | |
257 | still have the flow of control. Otherwise, we could just return | |
258 | (jump to the normal end of function epilogue). | |
259 | ||
260 | This is done in __throw in libgcc2.c when we know that a handler exists | |
261 | in a frame higher up the call stack than its immediate caller. | |
262 | ||
263 | To unwind, we find the unwind data associated with the frame, if any. | |
264 | If we don't find any, we call the library routine __terminate. If we do | |
265 | find it, we use the information to copy the saved register values from | |
266 | that frame into the register save area in the frame for __throw, return | |
267 | into a stub which updates the stack pointer, and jump to the handler. | |
268 | The normal function epilogue for __throw handles restoring the saved | |
269 | values into registers. | |
270 | ||
271 | When unwinding, we use this method if we know it will | |
272 | work (if DWARF2_UNWIND_INFO is defined). Otherwise, we know that | |
273 | an inline unwinder will have been emitted for any function that | |
274 | __unwind_function cannot unwind. The inline unwinder appears as a | |
275 | normal exception handler for the entire function, for any function | |
276 | that we know cannot be unwound by __unwind_function. We inform the | |
277 | compiler of whether a function can be unwound with | |
278 | __unwind_function by having DOESNT_NEED_UNWINDER evaluate to true | |
279 | when the unwinder isn't needed. __unwind_function is used as an | |
280 | action of last resort. If no other method can be used for | |
281 | unwinding, __unwind_function is used. If it cannot unwind, it | |
956d6950 | 282 | should call __terminate. |
ca55abae JM |
283 | |
284 | By default, if the target-specific backend doesn't supply a definition | |
285 | for __unwind_function and doesn't support DWARF2_UNWIND_INFO, inlined | |
286 | unwinders will be used instead. The main tradeoff here is in text space | |
287 | utilization. Obviously, if inline unwinders have to be generated | |
288 | repeatedly, this uses much more space than if a single routine is used. | |
2ed18e63 MS |
289 | |
290 | However, it is simply not possible on some platforms to write a | |
291 | generalized routine for doing stack unwinding without having some | |
ca55abae JM |
292 | form of additional data associated with each function. The current |
293 | implementation can encode this data in the form of additional | |
294 | machine instructions or as static data in tabular form. The later | |
295 | is called the unwind data. | |
12670d88 | 296 | |
ca55abae JM |
297 | The backend macro DOESNT_NEED_UNWINDER is used to conditionalize whether |
298 | or not per-function unwinders are needed. If DOESNT_NEED_UNWINDER is | |
299 | defined and has a non-zero value, a per-function unwinder is not emitted | |
300 | for the current function. If the static unwind data is supported, then | |
301 | a per-function unwinder is not emitted. | |
12670d88 | 302 | |
27a36778 | 303 | On some platforms it is possible that neither __unwind_function |
12670d88 | 304 | nor inlined unwinders are available. For these platforms it is not |
27a36778 | 305 | possible to throw through a function call, and abort will be |
2ed18e63 MS |
306 | invoked instead of performing the throw. |
307 | ||
ca55abae JM |
308 | The reason the unwind data may be needed is that on some platforms |
309 | the order and types of data stored on the stack can vary depending | |
310 | on the type of function, its arguments and returned values, and the | |
311 | compilation options used (optimization versus non-optimization, | |
312 | -fomit-frame-pointer, processor variations, etc). | |
313 | ||
314 | Unfortunately, this also means that throwing through functions that | |
315 | aren't compiled with exception handling support will still not be | |
316 | possible on some platforms. This problem is currently being | |
317 | investigated, but no solutions have been found that do not imply | |
318 | some unacceptable performance penalties. | |
319 | ||
2ed18e63 MS |
320 | Future directions: |
321 | ||
27a36778 | 322 | Currently __throw makes no differentiation between cleanups and |
2ed18e63 MS |
323 | user-defined exception regions. While this makes the implementation |
324 | simple, it also implies that it is impossible to determine if a | |
325 | user-defined exception handler exists for a given exception without | |
326 | completely unwinding the stack in the process. This is undesirable | |
327 | from the standpoint of debugging, as ideally it would be possible | |
328 | to trap unhandled exceptions in the debugger before the process of | |
329 | unwinding has even started. | |
330 | ||
331 | This problem can be solved by marking user-defined handlers in a | |
332 | special way (probably by adding additional bits to exception_table_list). | |
27a36778 | 333 | A two-pass scheme could then be used by __throw to iterate |
2ed18e63 MS |
334 | through the table. The first pass would search for a relevant |
335 | user-defined handler for the current context of the throw, and if | |
336 | one is found, the second pass would then invoke all needed cleanups | |
337 | before jumping to the user-defined handler. | |
338 | ||
339 | Many languages (including C++ and Ada) make execution of a | |
340 | user-defined handler conditional on the "type" of the exception | |
341 | thrown. (The type of the exception is actually the type of the data | |
342 | that is thrown with the exception.) It will thus be necessary for | |
27a36778 | 343 | __throw to be able to determine if a given user-defined |
2ed18e63 MS |
344 | exception handler will actually be executed, given the type of |
345 | exception. | |
346 | ||
347 | One scheme is to add additional information to exception_table_list | |
27a36778 | 348 | as to the types of exceptions accepted by each handler. __throw |
2ed18e63 MS |
349 | can do the type comparisons and then determine if the handler is |
350 | actually going to be executed. | |
351 | ||
352 | There is currently no significant level of debugging support | |
27a36778 | 353 | available, other than to place a breakpoint on __throw. While |
2ed18e63 MS |
354 | this is sufficient in most cases, it would be helpful to be able to |
355 | know where a given exception was going to be thrown to before it is | |
356 | actually thrown, and to be able to choose between stopping before | |
357 | every exception region (including cleanups), or just user-defined | |
358 | exception regions. This should be possible to do in the two-pass | |
27a36778 | 359 | scheme by adding additional labels to __throw for appropriate |
2ed18e63 MS |
360 | breakpoints, and additional debugger commands could be added to |
361 | query various state variables to determine what actions are to be | |
362 | performed next. | |
363 | ||
ca55abae JM |
364 | Another major problem that is being worked on is the issue with stack |
365 | unwinding on various platforms. Currently the only platforms that have | |
366 | support for the generation of a generic unwinder are the SPARC and MIPS. | |
367 | All other ports require per-function unwinders, which produce large | |
368 | amounts of code bloat. | |
27a36778 MS |
369 | |
370 | For setjmp/longjmp based exception handling, some of the details | |
371 | are as above, but there are some additional details. This section | |
372 | discusses the details. | |
373 | ||
374 | We don't use NOTE_INSN_EH_REGION_{BEG,END} pairs. We don't | |
375 | optimize EH regions yet. We don't have to worry about machine | |
376 | specific issues with unwinding the stack, as we rely upon longjmp | |
377 | for all the machine specific details. There is no variable context | |
378 | of a throw, just the one implied by the dynamic handler stack | |
379 | pointed to by the dynamic handler chain. There is no exception | |
956d6950 | 380 | table, and no calls to __register_exceptions. __sjthrow is used |
27a36778 MS |
381 | instead of __throw, and it works by using the dynamic handler |
382 | chain, and longjmp. -fasynchronous-exceptions has no effect, as | |
383 | the elimination of trivial exception regions is not yet performed. | |
384 | ||
385 | A frontend can set protect_cleanup_actions_with_terminate when all | |
386 | the cleanup actions should be protected with an EH region that | |
387 | calls terminate when an unhandled exception is throw. C++ does | |
388 | this, Ada does not. */ | |
4956d07c MS |
389 | |
390 | ||
391 | #include "config.h" | |
ca55abae | 392 | #include "defaults.h" |
9a0d1e1b | 393 | #include "eh-common.h" |
670ee920 | 394 | #include "system.h" |
4956d07c MS |
395 | #include "rtl.h" |
396 | #include "tree.h" | |
397 | #include "flags.h" | |
398 | #include "except.h" | |
399 | #include "function.h" | |
400 | #include "insn-flags.h" | |
401 | #include "expr.h" | |
402 | #include "insn-codes.h" | |
403 | #include "regs.h" | |
404 | #include "hard-reg-set.h" | |
405 | #include "insn-config.h" | |
406 | #include "recog.h" | |
407 | #include "output.h" | |
10f0ad3d | 408 | #include "toplev.h" |
4956d07c | 409 | |
27a36778 MS |
410 | /* One to use setjmp/longjmp method of generating code for exception |
411 | handling. */ | |
412 | ||
d1485032 | 413 | int exceptions_via_longjmp = 2; |
27a36778 MS |
414 | |
415 | /* One to enable asynchronous exception support. */ | |
416 | ||
417 | int asynchronous_exceptions = 0; | |
418 | ||
419 | /* One to protect cleanup actions with a handler that calls | |
420 | __terminate, zero otherwise. */ | |
421 | ||
e701eb4d | 422 | int protect_cleanup_actions_with_terminate; |
27a36778 | 423 | |
12670d88 | 424 | /* A list of labels used for exception handlers. Created by |
4956d07c MS |
425 | find_exception_handler_labels for the optimization passes. */ |
426 | ||
427 | rtx exception_handler_labels; | |
428 | ||
154bba13 TT |
429 | /* The EH context. Nonzero if the function has already |
430 | fetched a pointer to the EH context for exception handling. */ | |
27a36778 | 431 | |
154bba13 | 432 | rtx current_function_ehc; |
27a36778 | 433 | |
956d6950 | 434 | /* A stack used for keeping track of the currently active exception |
12670d88 | 435 | handling region. As each exception region is started, an entry |
4956d07c MS |
436 | describing the region is pushed onto this stack. The current |
437 | region can be found by looking at the top of the stack, and as we | |
12670d88 RK |
438 | exit regions, the corresponding entries are popped. |
439 | ||
27a36778 | 440 | Entries cannot overlap; they can be nested. So there is only one |
12670d88 RK |
441 | entry at most that corresponds to the current instruction, and that |
442 | is the entry on the top of the stack. */ | |
4956d07c | 443 | |
27a36778 | 444 | static struct eh_stack ehstack; |
4956d07c | 445 | |
9a0d1e1b AM |
446 | |
447 | /* This stack is used to represent what the current eh region is | |
448 | for the catch blocks beings processed */ | |
449 | ||
450 | static struct eh_stack catchstack; | |
451 | ||
12670d88 RK |
452 | /* A queue used for tracking which exception regions have closed but |
453 | whose handlers have not yet been expanded. Regions are emitted in | |
454 | groups in an attempt to improve paging performance. | |
455 | ||
456 | As we exit a region, we enqueue a new entry. The entries are then | |
27a36778 | 457 | dequeued during expand_leftover_cleanups and expand_start_all_catch, |
12670d88 RK |
458 | |
459 | We should redo things so that we either take RTL for the handler, | |
460 | or we expand the handler expressed as a tree immediately at region | |
461 | end time. */ | |
4956d07c | 462 | |
27a36778 | 463 | static struct eh_queue ehqueue; |
4956d07c | 464 | |
12670d88 | 465 | /* Insns for all of the exception handlers for the current function. |
abeeec2a | 466 | They are currently emitted by the frontend code. */ |
4956d07c MS |
467 | |
468 | rtx catch_clauses; | |
469 | ||
12670d88 RK |
470 | /* A TREE_CHAINed list of handlers for regions that are not yet |
471 | closed. The TREE_VALUE of each entry contains the handler for the | |
abeeec2a | 472 | corresponding entry on the ehstack. */ |
4956d07c | 473 | |
12670d88 | 474 | static tree protect_list; |
4956d07c MS |
475 | |
476 | /* Stacks to keep track of various labels. */ | |
477 | ||
12670d88 RK |
478 | /* Keeps track of the label to resume to should one want to resume |
479 | normal control flow out of a handler (instead of, say, returning to | |
1418bb67 | 480 | the caller of the current function or exiting the program). */ |
4956d07c MS |
481 | |
482 | struct label_node *caught_return_label_stack = NULL; | |
483 | ||
956d6950 JL |
484 | /* Keeps track of the label used as the context of a throw to rethrow an |
485 | exception to the outer exception region. */ | |
486 | ||
487 | struct label_node *outer_context_label_stack = NULL; | |
488 | ||
12670d88 | 489 | /* A random data area for the front end's own use. */ |
4956d07c MS |
490 | |
491 | struct label_node *false_label_stack = NULL; | |
492 | ||
242c13b0 JL |
493 | static void push_eh_entry PROTO((struct eh_stack *)); |
494 | static struct eh_entry * pop_eh_entry PROTO((struct eh_stack *)); | |
495 | static void enqueue_eh_entry PROTO((struct eh_queue *, struct eh_entry *)); | |
496 | static struct eh_entry * dequeue_eh_entry PROTO((struct eh_queue *)); | |
497 | static rtx call_get_eh_context PROTO((void)); | |
498 | static void start_dynamic_cleanup PROTO((tree, tree)); | |
499 | static void start_dynamic_handler PROTO((void)); | |
e701eb4d | 500 | static void expand_rethrow PROTO((rtx)); |
242c13b0 JL |
501 | static void output_exception_table_entry PROTO((FILE *, int)); |
502 | static int can_throw PROTO((rtx)); | |
503 | static rtx scan_region PROTO((rtx, int, int *)); | |
504 | static void eh_regs PROTO((rtx *, rtx *, int)); | |
505 | static void set_insn_eh_region PROTO((rtx *, int)); | |
e701eb4d | 506 | |
242c13b0 | 507 | rtx expand_builtin_return_addr PROTO((enum built_in_function, int, rtx)); |
4956d07c MS |
508 | \f |
509 | /* Various support routines to manipulate the various data structures | |
510 | used by the exception handling code. */ | |
511 | ||
512 | /* Push a label entry onto the given STACK. */ | |
513 | ||
514 | void | |
515 | push_label_entry (stack, rlabel, tlabel) | |
516 | struct label_node **stack; | |
517 | rtx rlabel; | |
518 | tree tlabel; | |
519 | { | |
520 | struct label_node *newnode | |
521 | = (struct label_node *) xmalloc (sizeof (struct label_node)); | |
522 | ||
523 | if (rlabel) | |
524 | newnode->u.rlabel = rlabel; | |
525 | else | |
526 | newnode->u.tlabel = tlabel; | |
527 | newnode->chain = *stack; | |
528 | *stack = newnode; | |
529 | } | |
530 | ||
531 | /* Pop a label entry from the given STACK. */ | |
532 | ||
533 | rtx | |
534 | pop_label_entry (stack) | |
535 | struct label_node **stack; | |
536 | { | |
537 | rtx label; | |
538 | struct label_node *tempnode; | |
539 | ||
540 | if (! *stack) | |
541 | return NULL_RTX; | |
542 | ||
543 | tempnode = *stack; | |
544 | label = tempnode->u.rlabel; | |
545 | *stack = (*stack)->chain; | |
546 | free (tempnode); | |
547 | ||
548 | return label; | |
549 | } | |
550 | ||
551 | /* Return the top element of the given STACK. */ | |
552 | ||
553 | tree | |
554 | top_label_entry (stack) | |
555 | struct label_node **stack; | |
556 | { | |
557 | if (! *stack) | |
558 | return NULL_TREE; | |
559 | ||
560 | return (*stack)->u.tlabel; | |
561 | } | |
562 | ||
9a0d1e1b AM |
563 | /* get an exception label. These must be on the permanent obstack */ |
564 | ||
565 | rtx | |
566 | gen_exception_label () | |
567 | { | |
568 | rtx lab; | |
569 | ||
570 | push_obstacks_nochange (); | |
571 | end_temporary_allocation (); | |
572 | lab = gen_label_rtx (); | |
573 | pop_obstacks (); | |
574 | return lab; | |
575 | } | |
576 | ||
478b0752 | 577 | /* Push a new eh_node entry onto STACK. */ |
4956d07c | 578 | |
478b0752 | 579 | static void |
4956d07c MS |
580 | push_eh_entry (stack) |
581 | struct eh_stack *stack; | |
582 | { | |
583 | struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node)); | |
584 | struct eh_entry *entry = (struct eh_entry *) xmalloc (sizeof (struct eh_entry)); | |
585 | ||
478b0752 | 586 | entry->outer_context = gen_label_rtx (); |
4956d07c | 587 | entry->finalization = NULL_TREE; |
9a0d1e1b AM |
588 | entry->label_used = 0; |
589 | entry->exception_handler_label = gen_exception_label (); | |
590 | ||
591 | node->entry = entry; | |
592 | node->chain = stack->top; | |
593 | stack->top = node; | |
594 | } | |
4956d07c | 595 | |
9a0d1e1b AM |
596 | /* push an existing entry onto a stack. */ |
597 | static void | |
598 | push_entry (stack, entry) | |
599 | struct eh_stack *stack; | |
600 | struct eh_entry *entry; | |
601 | { | |
602 | struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node)); | |
4956d07c MS |
603 | node->entry = entry; |
604 | node->chain = stack->top; | |
605 | stack->top = node; | |
4956d07c MS |
606 | } |
607 | ||
608 | /* Pop an entry from the given STACK. */ | |
609 | ||
610 | static struct eh_entry * | |
611 | pop_eh_entry (stack) | |
612 | struct eh_stack *stack; | |
613 | { | |
614 | struct eh_node *tempnode; | |
615 | struct eh_entry *tempentry; | |
616 | ||
617 | tempnode = stack->top; | |
618 | tempentry = tempnode->entry; | |
619 | stack->top = stack->top->chain; | |
620 | free (tempnode); | |
621 | ||
622 | return tempentry; | |
623 | } | |
624 | ||
625 | /* Enqueue an ENTRY onto the given QUEUE. */ | |
626 | ||
627 | static void | |
628 | enqueue_eh_entry (queue, entry) | |
629 | struct eh_queue *queue; | |
630 | struct eh_entry *entry; | |
631 | { | |
632 | struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node)); | |
633 | ||
634 | node->entry = entry; | |
635 | node->chain = NULL; | |
636 | ||
637 | if (queue->head == NULL) | |
638 | { | |
639 | queue->head = node; | |
640 | } | |
641 | else | |
642 | { | |
643 | queue->tail->chain = node; | |
644 | } | |
645 | queue->tail = node; | |
646 | } | |
647 | ||
648 | /* Dequeue an entry from the given QUEUE. */ | |
649 | ||
650 | static struct eh_entry * | |
651 | dequeue_eh_entry (queue) | |
652 | struct eh_queue *queue; | |
653 | { | |
654 | struct eh_node *tempnode; | |
655 | struct eh_entry *tempentry; | |
656 | ||
657 | if (queue->head == NULL) | |
658 | return NULL; | |
659 | ||
660 | tempnode = queue->head; | |
661 | queue->head = queue->head->chain; | |
662 | ||
663 | tempentry = tempnode->entry; | |
664 | free (tempnode); | |
665 | ||
666 | return tempentry; | |
667 | } | |
9a0d1e1b AM |
668 | |
669 | static void | |
670 | receive_exception_label (handler_label) | |
671 | rtx handler_label; | |
672 | { | |
673 | emit_label (handler_label); | |
674 | ||
675 | #ifdef HAVE_exception_receiver | |
676 | if (! exceptions_via_longjmp) | |
677 | if (HAVE_exception_receiver) | |
678 | emit_insn (gen_exception_receiver ()); | |
679 | #endif | |
680 | ||
681 | #ifdef HAVE_nonlocal_goto_receiver | |
682 | if (! exceptions_via_longjmp) | |
683 | if (HAVE_nonlocal_goto_receiver) | |
684 | emit_insn (gen_nonlocal_goto_receiver ()); | |
685 | #endif | |
686 | } | |
687 | ||
688 | ||
689 | struct func_eh_entry | |
690 | { | |
691 | int range_number; /* EH region number from EH NOTE insn's */ | |
692 | struct handler_info *handlers; | |
693 | }; | |
694 | ||
695 | ||
696 | /* table of function eh regions */ | |
697 | static struct func_eh_entry *function_eh_regions = NULL; | |
698 | static int num_func_eh_entries = 0; | |
699 | static int current_func_eh_entry = 0; | |
700 | ||
701 | #define SIZE_FUNC_EH(X) (sizeof (struct func_eh_entry) * X) | |
702 | ||
703 | /* Add a new eh_entry for this function, and base it off of the information | |
704 | in the EH_ENTRY parameter. A NULL parameter is invalid. The number | |
705 | returned is an number which uniquely identifies this exception range. */ | |
706 | ||
707 | int | |
708 | new_eh_region_entry (note_eh_region) | |
709 | int note_eh_region; | |
710 | { | |
711 | if (current_func_eh_entry == num_func_eh_entries) | |
712 | { | |
713 | if (num_func_eh_entries == 0) | |
714 | { | |
715 | function_eh_regions = | |
716 | (struct func_eh_entry *) malloc (SIZE_FUNC_EH (50)); | |
717 | num_func_eh_entries = 50; | |
718 | } | |
719 | else | |
720 | { | |
721 | num_func_eh_entries = num_func_eh_entries * 3 / 2; | |
722 | function_eh_regions = (struct func_eh_entry *) | |
723 | realloc (function_eh_regions, SIZE_FUNC_EH (num_func_eh_entries)); | |
724 | } | |
725 | } | |
726 | function_eh_regions[current_func_eh_entry].range_number = note_eh_region; | |
727 | function_eh_regions[current_func_eh_entry].handlers = NULL; | |
728 | ||
729 | return current_func_eh_entry++; | |
730 | } | |
731 | ||
732 | /* Add new handler information to an exception range. The first parameter | |
733 | specifies the range number (returned from new_eh_entry()). The second | |
734 | parameter specifies the handler. By default the handler is inserted at | |
735 | the end of the list. A handler list may contain only ONE NULL_TREE | |
736 | typeinfo entry. Regardless where it is positioned, a NULL_TREE entry | |
737 | is always output as the LAST handler in the exception table for a region. */ | |
738 | ||
739 | void | |
740 | add_new_handler (region, newhandler) | |
741 | int region; | |
742 | struct handler_info *newhandler; | |
743 | { | |
744 | struct handler_info *last; | |
745 | ||
746 | newhandler->next = NULL; | |
747 | last = function_eh_regions[region].handlers; | |
748 | if (last == NULL) | |
749 | function_eh_regions[region].handlers = newhandler; | |
750 | else | |
751 | { | |
752 | for ( ; last->next != NULL; last = last->next) | |
753 | last->next = newhandler; | |
754 | } | |
755 | } | |
756 | ||
9f8e6243 AM |
757 | /* Remove a handler label. The handler label is being deleted, so all |
758 | regions which reference this handler should have it removed from their | |
759 | list of possible handlers. Any region which has the final handler | |
760 | removed can be deleted. */ | |
761 | ||
762 | void remove_handler (removing_label) | |
763 | rtx removing_label; | |
764 | { | |
765 | struct handler_info *handler, *last; | |
766 | int x; | |
767 | for (x = 0 ; x < current_func_eh_entry; ++x) | |
768 | { | |
769 | last = NULL; | |
770 | handler = function_eh_regions[x].handlers; | |
771 | for ( ; handler; last = handler, handler = handler->next) | |
772 | if (handler->handler_label == removing_label) | |
773 | { | |
774 | if (last) | |
775 | { | |
776 | last->next = handler->next; | |
777 | handler = last; | |
778 | } | |
779 | else | |
780 | function_eh_regions[x].handlers = handler->next; | |
781 | } | |
782 | } | |
783 | } | |
784 | ||
9a0d1e1b AM |
785 | /* Create a new handler structure initialized with the handler label and |
786 | typeinfo fields passed in. */ | |
787 | ||
788 | struct handler_info * | |
789 | get_new_handler (handler, typeinfo) | |
790 | rtx handler; | |
791 | void *typeinfo; | |
792 | { | |
793 | struct handler_info* ptr; | |
794 | ptr = (struct handler_info *) malloc (sizeof (struct handler_info)); | |
795 | ptr->handler_label = handler; | |
796 | ptr->type_info = typeinfo; | |
797 | ptr->next = NULL; | |
798 | ||
799 | return ptr; | |
800 | } | |
801 | ||
802 | ||
803 | ||
804 | /* Find the index in function_eh_regions associated with a NOTE region. If | |
805 | the region cannot be found, a -1 is returned. This should never happen! */ | |
806 | ||
807 | int | |
808 | find_func_region (insn_region) | |
809 | int insn_region; | |
810 | { | |
811 | int x; | |
812 | for (x = 0; x < current_func_eh_entry; x++) | |
813 | if (function_eh_regions[x].range_number == insn_region) | |
814 | return x; | |
815 | ||
816 | return -1; | |
817 | } | |
818 | ||
819 | /* Get a pointer to the first handler in an exception region's list. */ | |
820 | ||
821 | struct handler_info * | |
822 | get_first_handler (region) | |
823 | int region; | |
824 | { | |
825 | return function_eh_regions[find_func_region (region)].handlers; | |
826 | } | |
827 | ||
828 | /* Clean out the function_eh_region table and free all memory */ | |
829 | ||
830 | static void | |
831 | clear_function_eh_region () | |
832 | { | |
833 | int x; | |
834 | struct handler_info *ptr, *next; | |
835 | for (x = 0; x < current_func_eh_entry; x++) | |
836 | for (ptr = function_eh_regions[x].handlers; ptr != NULL; ptr = next) | |
837 | { | |
838 | next = ptr->next; | |
839 | free (ptr); | |
840 | } | |
841 | free (function_eh_regions); | |
842 | num_func_eh_entries = 0; | |
843 | current_func_eh_entry = 0; | |
844 | } | |
845 | ||
846 | /* Make a duplicate of an exception region by copying all the handlers | |
847 | for an exception region. Return the new handler index. */ | |
848 | ||
849 | int | |
850 | duplicate_handlers (old_note_eh_region, new_note_eh_region) | |
851 | int old_note_eh_region, new_note_eh_region; | |
852 | { | |
853 | struct handler_info *ptr, *new_ptr; | |
854 | int new_region, region; | |
855 | ||
856 | region = find_func_region (old_note_eh_region); | |
857 | if (region == -1) | |
858 | error ("Cannot duplicate non-existant exception region."); | |
859 | ||
860 | if (find_func_region (new_note_eh_region) != -1) | |
861 | error ("Cannot duplicate EH region because new note region already exists"); | |
862 | ||
863 | new_region = new_eh_region_entry (new_note_eh_region); | |
864 | ptr = function_eh_regions[region].handlers; | |
865 | ||
866 | for ( ; ptr; ptr = ptr->next) | |
867 | { | |
868 | new_ptr = get_new_handler (ptr->handler_label, ptr->type_info); | |
869 | add_new_handler (new_region, new_ptr); | |
870 | } | |
871 | ||
872 | return new_region; | |
873 | } | |
874 | ||
4956d07c | 875 | \f |
38e01259 | 876 | /* Routine to see if exception handling is turned on. |
4956d07c | 877 | DO_WARN is non-zero if we want to inform the user that exception |
12670d88 RK |
878 | handling is turned off. |
879 | ||
880 | This is used to ensure that -fexceptions has been specified if the | |
abeeec2a | 881 | compiler tries to use any exception-specific functions. */ |
4956d07c MS |
882 | |
883 | int | |
884 | doing_eh (do_warn) | |
885 | int do_warn; | |
886 | { | |
887 | if (! flag_exceptions) | |
888 | { | |
889 | static int warned = 0; | |
890 | if (! warned && do_warn) | |
891 | { | |
892 | error ("exception handling disabled, use -fexceptions to enable"); | |
893 | warned = 1; | |
894 | } | |
895 | return 0; | |
896 | } | |
897 | return 1; | |
898 | } | |
899 | ||
12670d88 | 900 | /* Given a return address in ADDR, determine the address we should use |
abeeec2a | 901 | to find the corresponding EH region. */ |
4956d07c MS |
902 | |
903 | rtx | |
904 | eh_outer_context (addr) | |
905 | rtx addr; | |
906 | { | |
907 | /* First mask out any unwanted bits. */ | |
908 | #ifdef MASK_RETURN_ADDR | |
ca55abae | 909 | expand_and (addr, MASK_RETURN_ADDR, addr); |
4956d07c MS |
910 | #endif |
911 | ||
ca55abae JM |
912 | /* Then adjust to find the real return address. */ |
913 | #if defined (RETURN_ADDR_OFFSET) | |
914 | addr = plus_constant (addr, RETURN_ADDR_OFFSET); | |
4956d07c MS |
915 | #endif |
916 | ||
917 | return addr; | |
918 | } | |
919 | ||
27a36778 MS |
920 | /* Start a new exception region for a region of code that has a |
921 | cleanup action and push the HANDLER for the region onto | |
922 | protect_list. All of the regions created with add_partial_entry | |
923 | will be ended when end_protect_partials is invoked. */ | |
12670d88 RK |
924 | |
925 | void | |
926 | add_partial_entry (handler) | |
927 | tree handler; | |
928 | { | |
929 | expand_eh_region_start (); | |
930 | ||
abeeec2a | 931 | /* Make sure the entry is on the correct obstack. */ |
12670d88 RK |
932 | push_obstacks_nochange (); |
933 | resume_temporary_allocation (); | |
27a36778 MS |
934 | |
935 | /* Because this is a cleanup action, we may have to protect the handler | |
936 | with __terminate. */ | |
937 | handler = protect_with_terminate (handler); | |
938 | ||
12670d88 RK |
939 | protect_list = tree_cons (NULL_TREE, handler, protect_list); |
940 | pop_obstacks (); | |
941 | } | |
942 | ||
100d81d4 | 943 | /* Emit code to get EH context to current function. */ |
27a36778 | 944 | |
154bba13 | 945 | static rtx |
01eb7f9a | 946 | call_get_eh_context () |
27a36778 | 947 | { |
bb727b5a JM |
948 | static tree fn; |
949 | tree expr; | |
950 | ||
951 | if (fn == NULL_TREE) | |
952 | { | |
953 | tree fntype; | |
154bba13 | 954 | fn = get_identifier ("__get_eh_context"); |
bb727b5a JM |
955 | push_obstacks_nochange (); |
956 | end_temporary_allocation (); | |
957 | fntype = build_pointer_type (build_pointer_type | |
958 | (build_pointer_type (void_type_node))); | |
959 | fntype = build_function_type (fntype, NULL_TREE); | |
960 | fn = build_decl (FUNCTION_DECL, fn, fntype); | |
961 | DECL_EXTERNAL (fn) = 1; | |
962 | TREE_PUBLIC (fn) = 1; | |
963 | DECL_ARTIFICIAL (fn) = 1; | |
964 | TREE_READONLY (fn) = 1; | |
965 | make_decl_rtl (fn, NULL_PTR, 1); | |
966 | assemble_external (fn); | |
967 | pop_obstacks (); | |
968 | } | |
969 | ||
970 | expr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (fn)), fn); | |
971 | expr = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (fn)), | |
972 | expr, NULL_TREE, NULL_TREE); | |
973 | TREE_SIDE_EFFECTS (expr) = 1; | |
bb727b5a | 974 | |
100d81d4 | 975 | return copy_to_reg (expand_expr (expr, NULL_RTX, VOIDmode, 0)); |
154bba13 TT |
976 | } |
977 | ||
978 | /* Get a reference to the EH context. | |
979 | We will only generate a register for the current function EH context here, | |
980 | and emit a USE insn to mark that this is a EH context register. | |
981 | ||
982 | Later, emit_eh_context will emit needed call to __get_eh_context | |
983 | in libgcc2, and copy the value to the register we have generated. */ | |
984 | ||
985 | rtx | |
01eb7f9a | 986 | get_eh_context () |
154bba13 TT |
987 | { |
988 | if (current_function_ehc == 0) | |
989 | { | |
990 | rtx insn; | |
991 | ||
992 | current_function_ehc = gen_reg_rtx (Pmode); | |
993 | ||
38a448ca RH |
994 | insn = gen_rtx_USE (GET_MODE (current_function_ehc), |
995 | current_function_ehc); | |
154bba13 TT |
996 | insn = emit_insn_before (insn, get_first_nonparm_insn ()); |
997 | ||
998 | REG_NOTES (insn) | |
38a448ca RH |
999 | = gen_rtx_EXPR_LIST (REG_EH_CONTEXT, current_function_ehc, |
1000 | REG_NOTES (insn)); | |
154bba13 TT |
1001 | } |
1002 | return current_function_ehc; | |
1003 | } | |
1004 | ||
154bba13 TT |
1005 | /* Get a reference to the dynamic handler chain. It points to the |
1006 | pointer to the next element in the dynamic handler chain. It ends | |
1007 | when there are no more elements in the dynamic handler chain, when | |
1008 | the value is &top_elt from libgcc2.c. Immediately after the | |
1009 | pointer, is an area suitable for setjmp/longjmp when | |
1010 | DONT_USE_BUILTIN_SETJMP is defined, and an area suitable for | |
1011 | __builtin_setjmp/__builtin_longjmp when DONT_USE_BUILTIN_SETJMP | |
1012 | isn't defined. */ | |
1013 | ||
1014 | rtx | |
1015 | get_dynamic_handler_chain () | |
1016 | { | |
1017 | rtx ehc, dhc, result; | |
1018 | ||
01eb7f9a | 1019 | ehc = get_eh_context (); |
154bba13 TT |
1020 | dhc = ehc; |
1021 | ||
1022 | result = copy_to_reg (dhc); | |
1023 | ||
1024 | /* We don't want a copy of the dcc, but rather, the single dcc. */ | |
38a448ca | 1025 | return gen_rtx_MEM (Pmode, result); |
27a36778 MS |
1026 | } |
1027 | ||
1028 | /* Get a reference to the dynamic cleanup chain. It points to the | |
1029 | pointer to the next element in the dynamic cleanup chain. | |
1030 | Immediately after the pointer, are two Pmode variables, one for a | |
1031 | pointer to a function that performs the cleanup action, and the | |
1032 | second, the argument to pass to that function. */ | |
1033 | ||
1034 | rtx | |
1035 | get_dynamic_cleanup_chain () | |
1036 | { | |
154bba13 | 1037 | rtx dhc, dcc, result; |
27a36778 MS |
1038 | |
1039 | dhc = get_dynamic_handler_chain (); | |
1040 | dcc = plus_constant (dhc, GET_MODE_SIZE (Pmode)); | |
1041 | ||
154bba13 | 1042 | result = copy_to_reg (dcc); |
27a36778 MS |
1043 | |
1044 | /* We don't want a copy of the dcc, but rather, the single dcc. */ | |
38a448ca | 1045 | return gen_rtx_MEM (Pmode, result); |
154bba13 TT |
1046 | } |
1047 | ||
27a36778 MS |
1048 | /* Generate code to evaluate X and jump to LABEL if the value is nonzero. |
1049 | LABEL is an rtx of code CODE_LABEL, in this function. */ | |
1050 | ||
1051 | void | |
1052 | jumpif_rtx (x, label) | |
1053 | rtx x; | |
1054 | rtx label; | |
1055 | { | |
1056 | jumpif (make_tree (type_for_mode (GET_MODE (x), 0), x), label); | |
1057 | } | |
1058 | ||
1059 | /* Generate code to evaluate X and jump to LABEL if the value is zero. | |
1060 | LABEL is an rtx of code CODE_LABEL, in this function. */ | |
1061 | ||
1062 | void | |
1063 | jumpifnot_rtx (x, label) | |
1064 | rtx x; | |
1065 | rtx label; | |
1066 | { | |
1067 | jumpifnot (make_tree (type_for_mode (GET_MODE (x), 0), x), label); | |
1068 | } | |
1069 | ||
1070 | /* Start a dynamic cleanup on the EH runtime dynamic cleanup stack. | |
1071 | We just need to create an element for the cleanup list, and push it | |
1072 | into the chain. | |
1073 | ||
1074 | A dynamic cleanup is a cleanup action implied by the presence of an | |
1075 | element on the EH runtime dynamic cleanup stack that is to be | |
1076 | performed when an exception is thrown. The cleanup action is | |
1077 | performed by __sjthrow when an exception is thrown. Only certain | |
1078 | actions can be optimized into dynamic cleanup actions. For the | |
1079 | restrictions on what actions can be performed using this routine, | |
1080 | see expand_eh_region_start_tree. */ | |
1081 | ||
1082 | static void | |
1083 | start_dynamic_cleanup (func, arg) | |
1084 | tree func; | |
1085 | tree arg; | |
1086 | { | |
381127e8 | 1087 | rtx dcc; |
27a36778 MS |
1088 | rtx new_func, new_arg; |
1089 | rtx x, buf; | |
1090 | int size; | |
1091 | ||
1092 | /* We allocate enough room for a pointer to the function, and | |
1093 | one argument. */ | |
1094 | size = 2; | |
1095 | ||
1096 | /* XXX, FIXME: The stack space allocated this way is too long lived, | |
1097 | but there is no allocation routine that allocates at the level of | |
1098 | the last binding contour. */ | |
1099 | buf = assign_stack_local (BLKmode, | |
1100 | GET_MODE_SIZE (Pmode)*(size+1), | |
1101 | 0); | |
1102 | ||
1103 | buf = change_address (buf, Pmode, NULL_RTX); | |
1104 | ||
1105 | /* Store dcc into the first word of the newly allocated buffer. */ | |
1106 | ||
1107 | dcc = get_dynamic_cleanup_chain (); | |
1108 | emit_move_insn (buf, dcc); | |
1109 | ||
1110 | /* Store func and arg into the cleanup list element. */ | |
1111 | ||
38a448ca RH |
1112 | new_func = gen_rtx_MEM (Pmode, plus_constant (XEXP (buf, 0), |
1113 | GET_MODE_SIZE (Pmode))); | |
1114 | new_arg = gen_rtx_MEM (Pmode, plus_constant (XEXP (buf, 0), | |
1115 | GET_MODE_SIZE (Pmode)*2)); | |
27a36778 MS |
1116 | x = expand_expr (func, new_func, Pmode, 0); |
1117 | if (x != new_func) | |
1118 | emit_move_insn (new_func, x); | |
1119 | ||
1120 | x = expand_expr (arg, new_arg, Pmode, 0); | |
1121 | if (x != new_arg) | |
1122 | emit_move_insn (new_arg, x); | |
1123 | ||
1124 | /* Update the cleanup chain. */ | |
1125 | ||
1126 | emit_move_insn (dcc, XEXP (buf, 0)); | |
1127 | } | |
1128 | ||
1129 | /* Emit RTL to start a dynamic handler on the EH runtime dynamic | |
1130 | handler stack. This should only be used by expand_eh_region_start | |
1131 | or expand_eh_region_start_tree. */ | |
1132 | ||
1133 | static void | |
1134 | start_dynamic_handler () | |
1135 | { | |
1136 | rtx dhc, dcc; | |
6e6a07d2 | 1137 | rtx x, arg, buf; |
27a36778 MS |
1138 | int size; |
1139 | ||
6e6a07d2 | 1140 | #ifndef DONT_USE_BUILTIN_SETJMP |
27a36778 MS |
1141 | /* The number of Pmode words for the setjmp buffer, when using the |
1142 | builtin setjmp/longjmp, see expand_builtin, case | |
1143 | BUILT_IN_LONGJMP. */ | |
1144 | size = 5; | |
1145 | #else | |
1146 | #ifdef JMP_BUF_SIZE | |
1147 | size = JMP_BUF_SIZE; | |
1148 | #else | |
1149 | /* Should be large enough for most systems, if it is not, | |
1150 | JMP_BUF_SIZE should be defined with the proper value. It will | |
1151 | also tend to be larger than necessary for most systems, a more | |
1152 | optimal port will define JMP_BUF_SIZE. */ | |
1153 | size = FIRST_PSEUDO_REGISTER+2; | |
1154 | #endif | |
1155 | #endif | |
1156 | /* XXX, FIXME: The stack space allocated this way is too long lived, | |
1157 | but there is no allocation routine that allocates at the level of | |
1158 | the last binding contour. */ | |
1159 | arg = assign_stack_local (BLKmode, | |
1160 | GET_MODE_SIZE (Pmode)*(size+1), | |
1161 | 0); | |
1162 | ||
1163 | arg = change_address (arg, Pmode, NULL_RTX); | |
1164 | ||
1165 | /* Store dhc into the first word of the newly allocated buffer. */ | |
1166 | ||
1167 | dhc = get_dynamic_handler_chain (); | |
38a448ca RH |
1168 | dcc = gen_rtx_MEM (Pmode, plus_constant (XEXP (arg, 0), |
1169 | GET_MODE_SIZE (Pmode))); | |
27a36778 MS |
1170 | emit_move_insn (arg, dhc); |
1171 | ||
1172 | /* Zero out the start of the cleanup chain. */ | |
1173 | emit_move_insn (dcc, const0_rtx); | |
1174 | ||
1175 | /* The jmpbuf starts two words into the area allocated. */ | |
6e6a07d2 | 1176 | buf = plus_constant (XEXP (arg, 0), GET_MODE_SIZE (Pmode)*2); |
27a36778 | 1177 | |
6e6a07d2 | 1178 | #ifdef DONT_USE_BUILTIN_SETJMP |
27a36778 | 1179 | x = emit_library_call_value (setjmp_libfunc, NULL_RTX, 1, SImode, 1, |
6e6a07d2 | 1180 | buf, Pmode); |
6fd1c67b RH |
1181 | /* If we come back here for a catch, transfer control to the handler. */ |
1182 | jumpif_rtx (x, ehstack.top->entry->exception_handler_label); | |
6e6a07d2 | 1183 | #else |
6fd1c67b RH |
1184 | { |
1185 | /* A label to continue execution for the no exception case. */ | |
1186 | rtx noex = gen_label_rtx(); | |
1187 | x = expand_builtin_setjmp (buf, NULL_RTX, noex, | |
1188 | ehstack.top->entry->exception_handler_label); | |
1189 | emit_label (noex); | |
1190 | } | |
6e6a07d2 | 1191 | #endif |
27a36778 | 1192 | |
27a36778 MS |
1193 | /* We are committed to this, so update the handler chain. */ |
1194 | ||
1195 | emit_move_insn (dhc, XEXP (arg, 0)); | |
1196 | } | |
1197 | ||
1198 | /* Start an exception handling region for the given cleanup action. | |
12670d88 | 1199 | All instructions emitted after this point are considered to be part |
27a36778 MS |
1200 | of the region until expand_eh_region_end is invoked. CLEANUP is |
1201 | the cleanup action to perform. The return value is true if the | |
1202 | exception region was optimized away. If that case, | |
1203 | expand_eh_region_end does not need to be called for this cleanup, | |
1204 | nor should it be. | |
1205 | ||
1206 | This routine notices one particular common case in C++ code | |
1207 | generation, and optimizes it so as to not need the exception | |
1208 | region. It works by creating a dynamic cleanup action, instead of | |
38e01259 | 1209 | a using an exception region. */ |
27a36778 MS |
1210 | |
1211 | int | |
4c581243 MS |
1212 | expand_eh_region_start_tree (decl, cleanup) |
1213 | tree decl; | |
27a36778 MS |
1214 | tree cleanup; |
1215 | { | |
27a36778 MS |
1216 | /* This is the old code. */ |
1217 | if (! doing_eh (0)) | |
1218 | return 0; | |
1219 | ||
1220 | /* The optimization only applies to actions protected with | |
1221 | terminate, and only applies if we are using the setjmp/longjmp | |
1222 | codegen method. */ | |
1223 | if (exceptions_via_longjmp | |
1224 | && protect_cleanup_actions_with_terminate) | |
1225 | { | |
1226 | tree func, arg; | |
1227 | tree args; | |
1228 | ||
1229 | /* Ignore any UNSAVE_EXPR. */ | |
1230 | if (TREE_CODE (cleanup) == UNSAVE_EXPR) | |
1231 | cleanup = TREE_OPERAND (cleanup, 0); | |
1232 | ||
1233 | /* Further, it only applies if the action is a call, if there | |
1234 | are 2 arguments, and if the second argument is 2. */ | |
1235 | ||
1236 | if (TREE_CODE (cleanup) == CALL_EXPR | |
1237 | && (args = TREE_OPERAND (cleanup, 1)) | |
1238 | && (func = TREE_OPERAND (cleanup, 0)) | |
1239 | && (arg = TREE_VALUE (args)) | |
1240 | && (args = TREE_CHAIN (args)) | |
1241 | ||
1242 | /* is the second argument 2? */ | |
1243 | && TREE_CODE (TREE_VALUE (args)) == INTEGER_CST | |
1244 | && TREE_INT_CST_LOW (TREE_VALUE (args)) == 2 | |
1245 | && TREE_INT_CST_HIGH (TREE_VALUE (args)) == 0 | |
1246 | ||
1247 | /* Make sure there are no other arguments. */ | |
1248 | && TREE_CHAIN (args) == NULL_TREE) | |
1249 | { | |
1250 | /* Arrange for returns and gotos to pop the entry we make on the | |
1251 | dynamic cleanup stack. */ | |
4c581243 | 1252 | expand_dcc_cleanup (decl); |
27a36778 MS |
1253 | start_dynamic_cleanup (func, arg); |
1254 | return 1; | |
1255 | } | |
1256 | } | |
1257 | ||
4c581243 | 1258 | expand_eh_region_start_for_decl (decl); |
9762d48d | 1259 | ehstack.top->entry->finalization = cleanup; |
27a36778 MS |
1260 | |
1261 | return 0; | |
1262 | } | |
1263 | ||
4c581243 MS |
1264 | /* Just like expand_eh_region_start, except if a cleanup action is |
1265 | entered on the cleanup chain, the TREE_PURPOSE of the element put | |
1266 | on the chain is DECL. DECL should be the associated VAR_DECL, if | |
1267 | any, otherwise it should be NULL_TREE. */ | |
4956d07c MS |
1268 | |
1269 | void | |
4c581243 MS |
1270 | expand_eh_region_start_for_decl (decl) |
1271 | tree decl; | |
4956d07c MS |
1272 | { |
1273 | rtx note; | |
1274 | ||
1275 | /* This is the old code. */ | |
1276 | if (! doing_eh (0)) | |
1277 | return; | |
1278 | ||
27a36778 MS |
1279 | if (exceptions_via_longjmp) |
1280 | { | |
1281 | /* We need a new block to record the start and end of the | |
1282 | dynamic handler chain. We could always do this, but we | |
1283 | really want to permit jumping into such a block, and we want | |
1284 | to avoid any errors or performance impact in the SJ EH code | |
1285 | for now. */ | |
1286 | expand_start_bindings (0); | |
1287 | ||
1288 | /* But we don't need or want a new temporary level. */ | |
1289 | pop_temp_slots (); | |
1290 | ||
1291 | /* Mark this block as created by expand_eh_region_start. This | |
1292 | is so that we can pop the block with expand_end_bindings | |
1293 | automatically. */ | |
1294 | mark_block_as_eh_region (); | |
1295 | ||
1296 | /* Arrange for returns and gotos to pop the entry we make on the | |
1297 | dynamic handler stack. */ | |
4c581243 | 1298 | expand_dhc_cleanup (decl); |
27a36778 | 1299 | } |
4956d07c | 1300 | |
478b0752 | 1301 | push_eh_entry (&ehstack); |
9ad8a5f0 MS |
1302 | note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_BEG); |
1303 | NOTE_BLOCK_NUMBER (note) | |
1304 | = CODE_LABEL_NUMBER (ehstack.top->entry->exception_handler_label); | |
27a36778 MS |
1305 | if (exceptions_via_longjmp) |
1306 | start_dynamic_handler (); | |
4956d07c MS |
1307 | } |
1308 | ||
4c581243 MS |
1309 | /* Start an exception handling region. All instructions emitted after |
1310 | this point are considered to be part of the region until | |
1311 | expand_eh_region_end is invoked. */ | |
1312 | ||
1313 | void | |
1314 | expand_eh_region_start () | |
1315 | { | |
1316 | expand_eh_region_start_for_decl (NULL_TREE); | |
1317 | } | |
1318 | ||
27a36778 MS |
1319 | /* End an exception handling region. The information about the region |
1320 | is found on the top of ehstack. | |
12670d88 RK |
1321 | |
1322 | HANDLER is either the cleanup for the exception region, or if we're | |
1323 | marking the end of a try block, HANDLER is integer_zero_node. | |
1324 | ||
27a36778 | 1325 | HANDLER will be transformed to rtl when expand_leftover_cleanups |
abeeec2a | 1326 | is invoked. */ |
4956d07c MS |
1327 | |
1328 | void | |
1329 | expand_eh_region_end (handler) | |
1330 | tree handler; | |
1331 | { | |
4956d07c | 1332 | struct eh_entry *entry; |
9ad8a5f0 | 1333 | rtx note; |
4956d07c MS |
1334 | |
1335 | if (! doing_eh (0)) | |
1336 | return; | |
1337 | ||
1338 | entry = pop_eh_entry (&ehstack); | |
1339 | ||
9ad8a5f0 MS |
1340 | note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_END); |
1341 | NOTE_BLOCK_NUMBER (note) | |
1342 | = CODE_LABEL_NUMBER (entry->exception_handler_label); | |
e701eb4d JM |
1343 | if (exceptions_via_longjmp == 0 |
1344 | /* We share outer_context between regions; only emit it once. */ | |
1345 | && INSN_UID (entry->outer_context) == 0) | |
27a36778 | 1346 | { |
478b0752 | 1347 | rtx label; |
4956d07c | 1348 | |
478b0752 MS |
1349 | label = gen_label_rtx (); |
1350 | emit_jump (label); | |
1351 | ||
1352 | /* Emit a label marking the end of this exception region that | |
1353 | is used for rethrowing into the outer context. */ | |
1354 | emit_label (entry->outer_context); | |
e701eb4d | 1355 | expand_internal_throw (); |
4956d07c | 1356 | |
478b0752 | 1357 | emit_label (label); |
27a36778 | 1358 | } |
4956d07c MS |
1359 | |
1360 | entry->finalization = handler; | |
1361 | ||
9a0d1e1b AM |
1362 | /* create region entry in final exception table */ |
1363 | new_eh_region_entry (NOTE_BLOCK_NUMBER (note)); | |
1364 | ||
4956d07c MS |
1365 | enqueue_eh_entry (&ehqueue, entry); |
1366 | ||
27a36778 MS |
1367 | /* If we have already started ending the bindings, don't recurse. |
1368 | This only happens when exceptions_via_longjmp is true. */ | |
1369 | if (is_eh_region ()) | |
1370 | { | |
1371 | /* Because we don't need or want a new temporary level and | |
1372 | because we didn't create one in expand_eh_region_start, | |
1373 | create a fake one now to avoid removing one in | |
1374 | expand_end_bindings. */ | |
1375 | push_temp_slots (); | |
1376 | ||
1377 | mark_block_as_not_eh_region (); | |
1378 | ||
1379 | /* Maybe do this to prevent jumping in and so on... */ | |
1380 | expand_end_bindings (NULL_TREE, 0, 0); | |
1381 | } | |
4956d07c MS |
1382 | } |
1383 | ||
9762d48d JM |
1384 | /* End the EH region for a goto fixup. We only need them in the region-based |
1385 | EH scheme. */ | |
1386 | ||
1387 | void | |
1388 | expand_fixup_region_start () | |
1389 | { | |
1390 | if (! doing_eh (0) || exceptions_via_longjmp) | |
1391 | return; | |
1392 | ||
1393 | expand_eh_region_start (); | |
1394 | } | |
1395 | ||
1396 | /* End the EH region for a goto fixup. CLEANUP is the cleanup we just | |
1397 | expanded; to avoid running it twice if it throws, we look through the | |
1398 | ehqueue for a matching region and rethrow from its outer_context. */ | |
1399 | ||
1400 | void | |
1401 | expand_fixup_region_end (cleanup) | |
1402 | tree cleanup; | |
1403 | { | |
9762d48d | 1404 | struct eh_node *node; |
9762d48d JM |
1405 | |
1406 | if (! doing_eh (0) || exceptions_via_longjmp) | |
1407 | return; | |
1408 | ||
1409 | for (node = ehstack.top; node && node->entry->finalization != cleanup; ) | |
1410 | node = node->chain; | |
1411 | if (node == 0) | |
1412 | for (node = ehqueue.head; node && node->entry->finalization != cleanup; ) | |
1413 | node = node->chain; | |
1414 | if (node == 0) | |
1415 | abort (); | |
1416 | ||
e701eb4d | 1417 | ehstack.top->entry->outer_context = node->entry->outer_context; |
9762d48d | 1418 | |
e701eb4d JM |
1419 | /* Just rethrow. size_zero_node is just a NOP. */ |
1420 | expand_eh_region_end (size_zero_node); | |
9762d48d JM |
1421 | } |
1422 | ||
27a36778 MS |
1423 | /* If we are using the setjmp/longjmp EH codegen method, we emit a |
1424 | call to __sjthrow. | |
1425 | ||
1426 | Otherwise, we emit a call to __throw and note that we threw | |
1427 | something, so we know we need to generate the necessary code for | |
1428 | __throw. | |
12670d88 RK |
1429 | |
1430 | Before invoking throw, the __eh_pc variable must have been set up | |
1431 | to contain the PC being thrown from. This address is used by | |
27a36778 | 1432 | __throw to determine which exception region (if any) is |
abeeec2a | 1433 | responsible for handling the exception. */ |
4956d07c | 1434 | |
27a36778 | 1435 | void |
4956d07c MS |
1436 | emit_throw () |
1437 | { | |
27a36778 MS |
1438 | if (exceptions_via_longjmp) |
1439 | { | |
1440 | emit_library_call (sjthrow_libfunc, 0, VOIDmode, 0); | |
1441 | } | |
1442 | else | |
1443 | { | |
4956d07c | 1444 | #ifdef JUMP_TO_THROW |
27a36778 | 1445 | emit_indirect_jump (throw_libfunc); |
4956d07c | 1446 | #else |
27a36778 | 1447 | emit_library_call (throw_libfunc, 0, VOIDmode, 0); |
4956d07c | 1448 | #endif |
27a36778 | 1449 | } |
4956d07c MS |
1450 | emit_barrier (); |
1451 | } | |
1452 | ||
e701eb4d JM |
1453 | /* Throw the current exception. If appropriate, this is done by jumping |
1454 | to the next handler. */ | |
4956d07c MS |
1455 | |
1456 | void | |
e701eb4d | 1457 | expand_internal_throw () |
4956d07c | 1458 | { |
e701eb4d | 1459 | emit_throw (); |
4956d07c MS |
1460 | } |
1461 | ||
1462 | /* Called from expand_exception_blocks and expand_end_catch_block to | |
27a36778 | 1463 | emit any pending handlers/cleanups queued from expand_eh_region_end. */ |
4956d07c MS |
1464 | |
1465 | void | |
1466 | expand_leftover_cleanups () | |
1467 | { | |
1468 | struct eh_entry *entry; | |
1469 | ||
1470 | while ((entry = dequeue_eh_entry (&ehqueue)) != 0) | |
1471 | { | |
1472 | rtx prev; | |
1473 | ||
12670d88 RK |
1474 | /* A leftover try block. Shouldn't be one here. */ |
1475 | if (entry->finalization == integer_zero_node) | |
1476 | abort (); | |
1477 | ||
abeeec2a | 1478 | /* Output the label for the start of the exception handler. */ |
4956d07c | 1479 | |
9a0d1e1b | 1480 | receive_exception_label (entry->exception_handler_label); |
f51430ed | 1481 | |
9a0d1e1b AM |
1482 | /* register a handler for this cleanup region */ |
1483 | add_new_handler ( | |
1484 | find_func_region (CODE_LABEL_NUMBER (entry->exception_handler_label)), | |
1485 | get_new_handler (entry->exception_handler_label, NULL)); | |
05f5b2cd | 1486 | |
abeeec2a | 1487 | /* And now generate the insns for the handler. */ |
4956d07c MS |
1488 | expand_expr (entry->finalization, const0_rtx, VOIDmode, 0); |
1489 | ||
1490 | prev = get_last_insn (); | |
27a36778 | 1491 | if (prev == NULL || GET_CODE (prev) != BARRIER) |
e701eb4d JM |
1492 | /* Emit code to throw to the outer context if we fall off |
1493 | the end of the handler. */ | |
1494 | expand_rethrow (entry->outer_context); | |
4956d07c | 1495 | |
c7ae64f2 | 1496 | do_pending_stack_adjust (); |
4956d07c MS |
1497 | free (entry); |
1498 | } | |
1499 | } | |
1500 | ||
abeeec2a | 1501 | /* Called at the start of a block of try statements. */ |
12670d88 RK |
1502 | void |
1503 | expand_start_try_stmts () | |
1504 | { | |
1505 | if (! doing_eh (1)) | |
1506 | return; | |
1507 | ||
1508 | expand_eh_region_start (); | |
1509 | } | |
1510 | ||
9a0d1e1b AM |
1511 | /* Called to begin a catch clause. The parameter is the object which |
1512 | will be passed to the runtime type check routine. */ | |
1513 | void | |
1514 | expand_start_catch (rtime) | |
1515 | tree rtime; | |
1516 | { | |
1517 | rtx handler_label = catchstack.top->entry->exception_handler_label; | |
1518 | int insn_region_num = CODE_LABEL_NUMBER (handler_label); | |
1519 | int eh_region_entry = find_func_region (insn_region_num); | |
1520 | ||
1521 | /* If we've already issued this label, pick a new one */ | |
7ecb5d27 | 1522 | if (catchstack.top->entry->label_used) |
9a0d1e1b AM |
1523 | handler_label = gen_exception_label (); |
1524 | else | |
1525 | catchstack.top->entry->label_used = 1; | |
1526 | ||
1527 | receive_exception_label (handler_label); | |
1528 | ||
1529 | add_new_handler (eh_region_entry, get_new_handler (handler_label, rtime)); | |
1530 | } | |
1531 | ||
1532 | /* End a catch clause by dequeuing the current region */ | |
1533 | ||
1534 | void | |
1535 | expand_end_catch () | |
1536 | { | |
1537 | struct eh_entry *entry; | |
1538 | entry = pop_eh_entry (&catchstack); | |
1539 | free (entry); | |
1540 | } | |
1541 | ||
12670d88 RK |
1542 | /* Generate RTL for the start of a group of catch clauses. |
1543 | ||
1544 | It is responsible for starting a new instruction sequence for the | |
1545 | instructions in the catch block, and expanding the handlers for the | |
1546 | internally-generated exception regions nested within the try block | |
abeeec2a | 1547 | corresponding to this catch block. */ |
4956d07c MS |
1548 | |
1549 | void | |
1550 | expand_start_all_catch () | |
1551 | { | |
1552 | struct eh_entry *entry; | |
1553 | tree label; | |
e701eb4d | 1554 | rtx outer_context; |
4956d07c MS |
1555 | |
1556 | if (! doing_eh (1)) | |
1557 | return; | |
1558 | ||
e701eb4d | 1559 | outer_context = ehstack.top->entry->outer_context; |
1418bb67 | 1560 | |
abeeec2a | 1561 | /* End the try block. */ |
12670d88 RK |
1562 | expand_eh_region_end (integer_zero_node); |
1563 | ||
4956d07c MS |
1564 | emit_line_note (input_filename, lineno); |
1565 | label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE); | |
1566 | ||
12670d88 | 1567 | /* The label for the exception handling block that we will save. |
956d6950 | 1568 | This is Lresume in the documentation. */ |
4956d07c MS |
1569 | expand_label (label); |
1570 | ||
12670d88 | 1571 | /* Push the label that points to where normal flow is resumed onto |
abeeec2a | 1572 | the top of the label stack. */ |
4956d07c MS |
1573 | push_label_entry (&caught_return_label_stack, NULL_RTX, label); |
1574 | ||
1575 | /* Start a new sequence for all the catch blocks. We will add this | |
12670d88 | 1576 | to the global sequence catch_clauses when we have completed all |
4956d07c MS |
1577 | the handlers in this handler-seq. */ |
1578 | start_sequence (); | |
1579 | ||
9a0d1e1b AM |
1580 | entry = dequeue_eh_entry (&ehqueue); |
1581 | for ( ; entry->finalization != integer_zero_node; | |
1582 | entry = dequeue_eh_entry (&ehqueue)) | |
4956d07c MS |
1583 | { |
1584 | rtx prev; | |
1585 | ||
9a0d1e1b | 1586 | /* Emit the label for the cleanup handler for this region, and |
12670d88 RK |
1587 | expand the code for the handler. |
1588 | ||
1589 | Note that a catch region is handled as a side-effect here; | |
1590 | for a try block, entry->finalization will contain | |
1591 | integer_zero_node, so no code will be generated in the | |
1592 | expand_expr call below. But, the label for the handler will | |
1593 | still be emitted, so any code emitted after this point will | |
abeeec2a | 1594 | end up being the handler. */ |
9a0d1e1b AM |
1595 | |
1596 | receive_exception_label (entry->exception_handler_label); | |
05f5b2cd | 1597 | |
9a0d1e1b AM |
1598 | /* register a handler for this cleanup region */ |
1599 | add_new_handler ( | |
1600 | find_func_region (CODE_LABEL_NUMBER (entry->exception_handler_label)), | |
1601 | get_new_handler (entry->exception_handler_label, NULL)); | |
4956d07c | 1602 | |
9a0d1e1b | 1603 | /* And now generate the insns for the cleanup handler. */ |
27a36778 MS |
1604 | expand_expr (entry->finalization, const0_rtx, VOIDmode, 0); |
1605 | ||
4956d07c | 1606 | prev = get_last_insn (); |
12670d88 | 1607 | if (prev == NULL || GET_CODE (prev) != BARRIER) |
e701eb4d JM |
1608 | /* Code to throw out to outer context when we fall off end |
1609 | of the handler. We can't do this here for catch blocks, | |
1610 | so it's done in expand_end_all_catch instead. */ | |
1611 | expand_rethrow (entry->outer_context); | |
12670d88 | 1612 | |
f45ebe47 | 1613 | do_pending_stack_adjust (); |
4956d07c MS |
1614 | free (entry); |
1615 | } | |
e701eb4d | 1616 | |
9a0d1e1b AM |
1617 | /* At this point, all the cleanups are done, and the ehqueue now has |
1618 | the current exception region at its head. We dequeue it, and put it | |
1619 | on the catch stack. */ | |
1620 | ||
1621 | push_entry (&catchstack, entry); | |
1622 | ||
e701eb4d JM |
1623 | /* If we are not doing setjmp/longjmp EH, because we are reordered |
1624 | out of line, we arrange to rethrow in the outer context. We need to | |
1625 | do this because we are not physically within the region, if any, that | |
1626 | logically contains this catch block. */ | |
1627 | if (! exceptions_via_longjmp) | |
1628 | { | |
1629 | expand_eh_region_start (); | |
1630 | ehstack.top->entry->outer_context = outer_context; | |
1631 | } | |
4956d07c MS |
1632 | } |
1633 | ||
12670d88 RK |
1634 | /* Finish up the catch block. At this point all the insns for the |
1635 | catch clauses have already been generated, so we only have to add | |
1636 | them to the catch_clauses list. We also want to make sure that if | |
1637 | we fall off the end of the catch clauses that we rethrow to the | |
abeeec2a | 1638 | outer EH region. */ |
4956d07c MS |
1639 | |
1640 | void | |
1641 | expand_end_all_catch () | |
1642 | { | |
5dfa7520 | 1643 | rtx new_catch_clause, outer_context = NULL_RTX; |
4956d07c MS |
1644 | |
1645 | if (! doing_eh (1)) | |
1646 | return; | |
1647 | ||
e701eb4d | 1648 | if (! exceptions_via_longjmp) |
5dfa7520 JM |
1649 | { |
1650 | outer_context = ehstack.top->entry->outer_context; | |
1651 | ||
1652 | /* Finish the rethrow region. size_zero_node is just a NOP. */ | |
1653 | expand_eh_region_end (size_zero_node); | |
1654 | } | |
1655 | ||
e701eb4d JM |
1656 | /* Code to throw out to outer context, if we fall off end of catch |
1657 | handlers. This is rethrow (Lresume, same id, same obj) in the | |
1658 | documentation. We use Lresume because we know that it will throw | |
1659 | to the correct context. | |
12670d88 | 1660 | |
e701eb4d JM |
1661 | In other words, if the catch handler doesn't exit or return, we |
1662 | do a "throw" (using the address of Lresume as the point being | |
1663 | thrown from) so that the outer EH region can then try to process | |
1664 | the exception. */ | |
1665 | expand_rethrow (outer_context); | |
4956d07c MS |
1666 | |
1667 | /* Now we have the complete catch sequence. */ | |
1668 | new_catch_clause = get_insns (); | |
1669 | end_sequence (); | |
1670 | ||
1671 | /* This level of catch blocks is done, so set up the successful | |
1672 | catch jump label for the next layer of catch blocks. */ | |
1673 | pop_label_entry (&caught_return_label_stack); | |
956d6950 | 1674 | pop_label_entry (&outer_context_label_stack); |
4956d07c MS |
1675 | |
1676 | /* Add the new sequence of catches to the main one for this function. */ | |
1677 | push_to_sequence (catch_clauses); | |
1678 | emit_insns (new_catch_clause); | |
1679 | catch_clauses = get_insns (); | |
1680 | end_sequence (); | |
1681 | ||
1682 | /* Here we fall through into the continuation code. */ | |
1683 | } | |
1684 | ||
e701eb4d JM |
1685 | /* Rethrow from the outer context LABEL. */ |
1686 | ||
1687 | static void | |
1688 | expand_rethrow (label) | |
1689 | rtx label; | |
1690 | { | |
1691 | if (exceptions_via_longjmp) | |
1692 | emit_throw (); | |
1693 | else | |
1694 | emit_jump (label); | |
1695 | } | |
1696 | ||
12670d88 | 1697 | /* End all the pending exception regions on protect_list. The handlers |
27a36778 | 1698 | will be emitted when expand_leftover_cleanups is invoked. */ |
4956d07c MS |
1699 | |
1700 | void | |
1701 | end_protect_partials () | |
1702 | { | |
1703 | while (protect_list) | |
1704 | { | |
1705 | expand_eh_region_end (TREE_VALUE (protect_list)); | |
1706 | protect_list = TREE_CHAIN (protect_list); | |
1707 | } | |
1708 | } | |
27a36778 MS |
1709 | |
1710 | /* Arrange for __terminate to be called if there is an unhandled throw | |
1711 | from within E. */ | |
1712 | ||
1713 | tree | |
1714 | protect_with_terminate (e) | |
1715 | tree e; | |
1716 | { | |
1717 | /* We only need to do this when using setjmp/longjmp EH and the | |
1718 | language requires it, as otherwise we protect all of the handlers | |
1719 | at once, if we need to. */ | |
1720 | if (exceptions_via_longjmp && protect_cleanup_actions_with_terminate) | |
1721 | { | |
1722 | tree handler, result; | |
1723 | ||
1724 | /* All cleanups must be on the function_obstack. */ | |
1725 | push_obstacks_nochange (); | |
1726 | resume_temporary_allocation (); | |
1727 | ||
1728 | handler = make_node (RTL_EXPR); | |
1729 | TREE_TYPE (handler) = void_type_node; | |
1730 | RTL_EXPR_RTL (handler) = const0_rtx; | |
1731 | TREE_SIDE_EFFECTS (handler) = 1; | |
1732 | start_sequence_for_rtl_expr (handler); | |
1733 | ||
1734 | emit_library_call (terminate_libfunc, 0, VOIDmode, 0); | |
1735 | emit_barrier (); | |
1736 | ||
1737 | RTL_EXPR_SEQUENCE (handler) = get_insns (); | |
1738 | end_sequence (); | |
1739 | ||
1740 | result = build (TRY_CATCH_EXPR, TREE_TYPE (e), e, handler); | |
1741 | TREE_SIDE_EFFECTS (result) = TREE_SIDE_EFFECTS (e); | |
1742 | TREE_THIS_VOLATILE (result) = TREE_THIS_VOLATILE (e); | |
1743 | TREE_READONLY (result) = TREE_READONLY (e); | |
1744 | ||
1745 | pop_obstacks (); | |
1746 | ||
1747 | e = result; | |
1748 | } | |
1749 | ||
1750 | return e; | |
1751 | } | |
4956d07c MS |
1752 | \f |
1753 | /* The exception table that we build that is used for looking up and | |
12670d88 RK |
1754 | dispatching exceptions, the current number of entries, and its |
1755 | maximum size before we have to extend it. | |
1756 | ||
1757 | The number in eh_table is the code label number of the exception | |
27a36778 MS |
1758 | handler for the region. This is added by add_eh_table_entry and |
1759 | used by output_exception_table_entry. */ | |
12670d88 | 1760 | |
9a0d1e1b AM |
1761 | static int *eh_table = NULL; |
1762 | static int eh_table_size = 0; | |
1763 | static int eh_table_max_size = 0; | |
4956d07c MS |
1764 | |
1765 | /* Note the need for an exception table entry for region N. If we | |
12670d88 RK |
1766 | don't need to output an explicit exception table, avoid all of the |
1767 | extra work. | |
1768 | ||
1769 | Called from final_scan_insn when a NOTE_INSN_EH_REGION_BEG is seen. | |
9a0d1e1b | 1770 | (Or NOTE_INSN_EH_REGION_END sometimes) |
12670d88 | 1771 | N is the NOTE_BLOCK_NUMBER of the note, which comes from the code |
abeeec2a | 1772 | label number of the exception handler for the region. */ |
4956d07c MS |
1773 | |
1774 | void | |
1775 | add_eh_table_entry (n) | |
1776 | int n; | |
1777 | { | |
1778 | #ifndef OMIT_EH_TABLE | |
1779 | if (eh_table_size >= eh_table_max_size) | |
1780 | { | |
1781 | if (eh_table) | |
1782 | { | |
1783 | eh_table_max_size += eh_table_max_size>>1; | |
1784 | ||
1785 | if (eh_table_max_size < 0) | |
1786 | abort (); | |
1787 | ||
ca55abae JM |
1788 | eh_table = (int *) xrealloc (eh_table, |
1789 | eh_table_max_size * sizeof (int)); | |
4956d07c MS |
1790 | } |
1791 | else | |
1792 | { | |
1793 | eh_table_max_size = 252; | |
1794 | eh_table = (int *) xmalloc (eh_table_max_size * sizeof (int)); | |
1795 | } | |
1796 | } | |
1797 | eh_table[eh_table_size++] = n; | |
1798 | #endif | |
1799 | } | |
1800 | ||
12670d88 RK |
1801 | /* Return a non-zero value if we need to output an exception table. |
1802 | ||
1803 | On some platforms, we don't have to output a table explicitly. | |
1804 | This routine doesn't mean we don't have one. */ | |
4956d07c MS |
1805 | |
1806 | int | |
1807 | exception_table_p () | |
1808 | { | |
1809 | if (eh_table) | |
1810 | return 1; | |
1811 | ||
1812 | return 0; | |
1813 | } | |
1814 | ||
38e01259 | 1815 | /* Output the entry of the exception table corresponding to the |
12670d88 RK |
1816 | exception region numbered N to file FILE. |
1817 | ||
1818 | N is the code label number corresponding to the handler of the | |
abeeec2a | 1819 | region. */ |
4956d07c MS |
1820 | |
1821 | static void | |
1822 | output_exception_table_entry (file, n) | |
1823 | FILE *file; | |
1824 | int n; | |
1825 | { | |
1826 | char buf[256]; | |
1827 | rtx sym; | |
9a0d1e1b AM |
1828 | struct handler_info *handler; |
1829 | ||
1830 | handler = get_first_handler (n); | |
4956d07c | 1831 | |
9a0d1e1b AM |
1832 | for ( ; handler != NULL; handler = handler->next) |
1833 | { | |
1834 | ASM_GENERATE_INTERNAL_LABEL (buf, "LEHB", n); | |
1835 | sym = gen_rtx_SYMBOL_REF (Pmode, buf); | |
1836 | assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1); | |
4956d07c | 1837 | |
9a0d1e1b AM |
1838 | ASM_GENERATE_INTERNAL_LABEL (buf, "LEHE", n); |
1839 | sym = gen_rtx_SYMBOL_REF (Pmode, buf); | |
1840 | assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1); | |
1841 | ||
1842 | assemble_integer (handler->handler_label, | |
1843 | POINTER_SIZE / BITS_PER_UNIT, 1); | |
4956d07c | 1844 | |
a1622f83 AM |
1845 | if (flag_new_exceptions) |
1846 | { | |
1847 | if (handler->type_info == NULL) | |
1848 | assemble_integer (const0_rtx, POINTER_SIZE / BITS_PER_UNIT, 1); | |
1849 | else | |
1850 | output_constant ((tree)(handler->type_info), | |
9a0d1e1b | 1851 | POINTER_SIZE / BITS_PER_UNIT); |
a1622f83 | 1852 | } |
9a0d1e1b AM |
1853 | putc ('\n', file); /* blank line */ |
1854 | } | |
4956d07c MS |
1855 | } |
1856 | ||
abeeec2a | 1857 | /* Output the exception table if we have and need one. */ |
4956d07c | 1858 | |
9a0d1e1b AM |
1859 | static short language_code = 0; |
1860 | static short version_code = 0; | |
1861 | ||
1862 | /* This routine will set the language code for exceptions. */ | |
1863 | void set_exception_lang_code (code) | |
1864 | short code; | |
1865 | { | |
1866 | language_code = code; | |
1867 | } | |
1868 | ||
1869 | /* This routine will set the language version code for exceptions. */ | |
1870 | void set_exception_version_code (code) | |
1871 | short code; | |
1872 | { | |
1873 | version_code = code; | |
1874 | } | |
1875 | ||
9a0d1e1b | 1876 | |
4956d07c MS |
1877 | void |
1878 | output_exception_table () | |
1879 | { | |
1880 | int i; | |
1881 | extern FILE *asm_out_file; | |
1882 | ||
ca55abae | 1883 | if (! doing_eh (0) || ! eh_table) |
4956d07c MS |
1884 | return; |
1885 | ||
1886 | exception_section (); | |
1887 | ||
1888 | /* Beginning marker for table. */ | |
1889 | assemble_align (GET_MODE_ALIGNMENT (ptr_mode)); | |
1890 | assemble_label ("__EXCEPTION_TABLE__"); | |
1891 | ||
a1622f83 AM |
1892 | if (flag_new_exceptions) |
1893 | { | |
1894 | assemble_integer (GEN_INT (NEW_EH_RUNTIME), | |
1895 | POINTER_SIZE / BITS_PER_UNIT, 1); | |
1896 | assemble_integer (GEN_INT (language_code), 2 , 1); | |
1897 | assemble_integer (GEN_INT (version_code), 2 , 1); | |
1898 | ||
1899 | /* Add enough padding to make sure table aligns on a pointer boundry. */ | |
1900 | i = GET_MODE_ALIGNMENT (ptr_mode) / BITS_PER_UNIT - 4; | |
1901 | for ( ; i < 0; i = i + GET_MODE_ALIGNMENT (ptr_mode) / BITS_PER_UNIT) | |
1902 | ; | |
1903 | if (i != 0) | |
1904 | assemble_integer (const0_rtx, i , 1); | |
1905 | } | |
9a0d1e1b | 1906 | |
4956d07c MS |
1907 | for (i = 0; i < eh_table_size; ++i) |
1908 | output_exception_table_entry (asm_out_file, eh_table[i]); | |
1909 | ||
1910 | free (eh_table); | |
9a0d1e1b | 1911 | clear_function_eh_region (); |
4956d07c MS |
1912 | |
1913 | /* Ending marker for table. */ | |
4956d07c | 1914 | assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1); |
a1622f83 | 1915 | |
9a0d1e1b AM |
1916 | /* for binary compatability, the old __throw checked the second |
1917 | position for a -1, so we should output at least 2 -1's */ | |
a1622f83 AM |
1918 | if (! flag_new_exceptions) |
1919 | assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1); | |
1920 | ||
4956d07c MS |
1921 | putc ('\n', asm_out_file); /* blank line */ |
1922 | } | |
4956d07c | 1923 | \f |
154bba13 TT |
1924 | /* Emit code to get EH context. |
1925 | ||
1926 | We have to scan thru the code to find possible EH context registers. | |
1927 | Inlined functions may use it too, and thus we'll have to be able | |
1928 | to change them too. | |
1929 | ||
1930 | This is done only if using exceptions_via_longjmp. */ | |
1931 | ||
1932 | void | |
1933 | emit_eh_context () | |
1934 | { | |
1935 | rtx insn; | |
1936 | rtx ehc = 0; | |
1937 | ||
1938 | if (! doing_eh (0)) | |
1939 | return; | |
1940 | ||
1941 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) | |
1942 | if (GET_CODE (insn) == INSN | |
1943 | && GET_CODE (PATTERN (insn)) == USE) | |
1944 | { | |
1945 | rtx reg = find_reg_note (insn, REG_EH_CONTEXT, 0); | |
1946 | if (reg) | |
1947 | { | |
1948 | rtx insns; | |
1949 | ||
100d81d4 JM |
1950 | start_sequence (); |
1951 | ||
d9c92f32 JM |
1952 | /* If this is the first use insn, emit the call here. This |
1953 | will always be at the top of our function, because if | |
1954 | expand_inline_function notices a REG_EH_CONTEXT note, it | |
1955 | adds a use insn to this function as well. */ | |
154bba13 | 1956 | if (ehc == 0) |
01eb7f9a | 1957 | ehc = call_get_eh_context (); |
154bba13 | 1958 | |
154bba13 TT |
1959 | emit_move_insn (XEXP (reg, 0), ehc); |
1960 | insns = get_insns (); | |
1961 | end_sequence (); | |
1962 | ||
1963 | emit_insns_before (insns, insn); | |
1964 | } | |
1965 | } | |
1966 | } | |
1967 | ||
12670d88 RK |
1968 | /* Scan the current insns and build a list of handler labels. The |
1969 | resulting list is placed in the global variable exception_handler_labels. | |
1970 | ||
1971 | It is called after the last exception handling region is added to | |
1972 | the current function (when the rtl is almost all built for the | |
1973 | current function) and before the jump optimization pass. */ | |
4956d07c MS |
1974 | |
1975 | void | |
1976 | find_exception_handler_labels () | |
1977 | { | |
1978 | rtx insn; | |
4956d07c MS |
1979 | |
1980 | exception_handler_labels = NULL_RTX; | |
1981 | ||
1982 | /* If we aren't doing exception handling, there isn't much to check. */ | |
1983 | if (! doing_eh (0)) | |
1984 | return; | |
1985 | ||
12670d88 RK |
1986 | /* For each start of a region, add its label to the list. */ |
1987 | ||
4956d07c MS |
1988 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) |
1989 | { | |
9a0d1e1b | 1990 | struct handler_info* ptr; |
4956d07c MS |
1991 | if (GET_CODE (insn) == NOTE |
1992 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG) | |
1993 | { | |
9a0d1e1b AM |
1994 | ptr = get_first_handler (NOTE_BLOCK_NUMBER (insn)); |
1995 | for ( ; ptr; ptr = ptr->next) | |
1996 | { | |
1997 | /* make sure label isn't in the list already */ | |
1998 | rtx x; | |
1999 | for (x = exception_handler_labels; x; x = XEXP (x, 1)) | |
2000 | if (XEXP (x, 0) == ptr->handler_label) | |
2001 | break; | |
2002 | if (! x) | |
2003 | exception_handler_labels = gen_rtx_EXPR_LIST (VOIDmode, | |
2004 | ptr->handler_label, exception_handler_labels); | |
2005 | } | |
4956d07c MS |
2006 | } |
2007 | } | |
9a0d1e1b AM |
2008 | } |
2009 | ||
2010 | /* Return a value of 1 if the parameter label number is an exception handler | |
2011 | label. Return 0 otherwise. */ | |
988cea7d | 2012 | |
9a0d1e1b AM |
2013 | int |
2014 | is_exception_handler_label (lab) | |
2015 | int lab; | |
2016 | { | |
2017 | rtx x; | |
2018 | for (x = exception_handler_labels ; x ; x = XEXP (x, 1)) | |
2019 | if (lab == CODE_LABEL_NUMBER (XEXP (x, 0))) | |
2020 | return 1; | |
2021 | return 0; | |
4956d07c MS |
2022 | } |
2023 | ||
12670d88 RK |
2024 | /* Perform sanity checking on the exception_handler_labels list. |
2025 | ||
2026 | Can be called after find_exception_handler_labels is called to | |
2027 | build the list of exception handlers for the current function and | |
2028 | before we finish processing the current function. */ | |
4956d07c MS |
2029 | |
2030 | void | |
2031 | check_exception_handler_labels () | |
2032 | { | |
9a0d1e1b | 2033 | rtx insn, insn2; |
4956d07c MS |
2034 | |
2035 | /* If we aren't doing exception handling, there isn't much to check. */ | |
2036 | if (! doing_eh (0)) | |
2037 | return; | |
2038 | ||
9a0d1e1b AM |
2039 | /* Make sure there is no more than 1 copy of a label */ |
2040 | for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1)) | |
4956d07c | 2041 | { |
9a0d1e1b AM |
2042 | int count = 0; |
2043 | for (insn2 = exception_handler_labels; insn2; insn2 = XEXP (insn2, 1)) | |
2044 | if (XEXP (insn, 0) == XEXP (insn2, 0)) | |
2045 | count++; | |
2046 | if (count != 1) | |
2047 | warning ("Counted %d copies of EH region %d in list.\n", count, | |
2048 | CODE_LABEL_NUMBER (insn)); | |
4956d07c MS |
2049 | } |
2050 | ||
4956d07c MS |
2051 | } |
2052 | \f | |
2053 | /* This group of functions initializes the exception handling data | |
2054 | structures at the start of the compilation, initializes the data | |
12670d88 | 2055 | structures at the start of a function, and saves and restores the |
4956d07c MS |
2056 | exception handling data structures for the start/end of a nested |
2057 | function. */ | |
2058 | ||
2059 | /* Toplevel initialization for EH things. */ | |
2060 | ||
2061 | void | |
2062 | init_eh () | |
2063 | { | |
4956d07c MS |
2064 | } |
2065 | ||
abeeec2a | 2066 | /* Initialize the per-function EH information. */ |
4956d07c MS |
2067 | |
2068 | void | |
2069 | init_eh_for_function () | |
2070 | { | |
2071 | ehstack.top = 0; | |
9a0d1e1b | 2072 | catchstack.top = 0; |
4956d07c MS |
2073 | ehqueue.head = ehqueue.tail = 0; |
2074 | catch_clauses = NULL_RTX; | |
2075 | false_label_stack = 0; | |
2076 | caught_return_label_stack = 0; | |
2077 | protect_list = NULL_TREE; | |
154bba13 | 2078 | current_function_ehc = NULL_RTX; |
4956d07c MS |
2079 | } |
2080 | ||
12670d88 RK |
2081 | /* Save some of the per-function EH info into the save area denoted by |
2082 | P. | |
2083 | ||
27a36778 | 2084 | This is currently called from save_stmt_status. */ |
4956d07c MS |
2085 | |
2086 | void | |
2087 | save_eh_status (p) | |
2088 | struct function *p; | |
2089 | { | |
3a88cbd1 JL |
2090 | if (p == NULL) |
2091 | abort (); | |
12670d88 | 2092 | |
4956d07c | 2093 | p->ehstack = ehstack; |
9a0d1e1b | 2094 | p->catchstack = catchstack; |
4956d07c MS |
2095 | p->ehqueue = ehqueue; |
2096 | p->catch_clauses = catch_clauses; | |
2097 | p->false_label_stack = false_label_stack; | |
2098 | p->caught_return_label_stack = caught_return_label_stack; | |
2099 | p->protect_list = protect_list; | |
154bba13 | 2100 | p->ehc = current_function_ehc; |
4956d07c | 2101 | |
6e1f1f93 | 2102 | init_eh_for_function (); |
4956d07c MS |
2103 | } |
2104 | ||
12670d88 RK |
2105 | /* Restore the per-function EH info saved into the area denoted by P. |
2106 | ||
abeeec2a | 2107 | This is currently called from restore_stmt_status. */ |
4956d07c MS |
2108 | |
2109 | void | |
2110 | restore_eh_status (p) | |
2111 | struct function *p; | |
2112 | { | |
3a88cbd1 JL |
2113 | if (p == NULL) |
2114 | abort (); | |
12670d88 | 2115 | |
4956d07c MS |
2116 | protect_list = p->protect_list; |
2117 | caught_return_label_stack = p->caught_return_label_stack; | |
2118 | false_label_stack = p->false_label_stack; | |
2119 | catch_clauses = p->catch_clauses; | |
2120 | ehqueue = p->ehqueue; | |
2121 | ehstack = p->ehstack; | |
9a0d1e1b | 2122 | catchstack = p->catchstack; |
154bba13 | 2123 | current_function_ehc = p->ehc; |
4956d07c MS |
2124 | } |
2125 | \f | |
2126 | /* This section is for the exception handling specific optimization | |
2127 | pass. First are the internal routines, and then the main | |
2128 | optimization pass. */ | |
2129 | ||
2130 | /* Determine if the given INSN can throw an exception. */ | |
2131 | ||
2132 | static int | |
2133 | can_throw (insn) | |
2134 | rtx insn; | |
2135 | { | |
abeeec2a | 2136 | /* Calls can always potentially throw exceptions. */ |
4956d07c MS |
2137 | if (GET_CODE (insn) == CALL_INSN) |
2138 | return 1; | |
2139 | ||
27a36778 MS |
2140 | if (asynchronous_exceptions) |
2141 | { | |
2142 | /* If we wanted asynchronous exceptions, then everything but NOTEs | |
2143 | and CODE_LABELs could throw. */ | |
2144 | if (GET_CODE (insn) != NOTE && GET_CODE (insn) != CODE_LABEL) | |
2145 | return 1; | |
2146 | } | |
4956d07c MS |
2147 | |
2148 | return 0; | |
2149 | } | |
2150 | ||
12670d88 RK |
2151 | /* Scan a exception region looking for the matching end and then |
2152 | remove it if possible. INSN is the start of the region, N is the | |
2153 | region number, and DELETE_OUTER is to note if anything in this | |
2154 | region can throw. | |
2155 | ||
2156 | Regions are removed if they cannot possibly catch an exception. | |
27a36778 | 2157 | This is determined by invoking can_throw on each insn within the |
12670d88 RK |
2158 | region; if can_throw returns true for any of the instructions, the |
2159 | region can catch an exception, since there is an insn within the | |
2160 | region that is capable of throwing an exception. | |
2161 | ||
2162 | Returns the NOTE_INSN_EH_REGION_END corresponding to this region, or | |
27a36778 | 2163 | calls abort if it can't find one. |
12670d88 RK |
2164 | |
2165 | Can abort if INSN is not a NOTE_INSN_EH_REGION_BEGIN, or if N doesn't | |
abeeec2a | 2166 | correspond to the region number, or if DELETE_OUTER is NULL. */ |
4956d07c MS |
2167 | |
2168 | static rtx | |
2169 | scan_region (insn, n, delete_outer) | |
2170 | rtx insn; | |
2171 | int n; | |
2172 | int *delete_outer; | |
2173 | { | |
2174 | rtx start = insn; | |
2175 | ||
2176 | /* Assume we can delete the region. */ | |
2177 | int delete = 1; | |
2178 | ||
3a88cbd1 JL |
2179 | if (insn == NULL_RTX |
2180 | || GET_CODE (insn) != NOTE | |
2181 | || NOTE_LINE_NUMBER (insn) != NOTE_INSN_EH_REGION_BEG | |
2182 | || NOTE_BLOCK_NUMBER (insn) != n | |
2183 | || delete_outer == NULL) | |
2184 | abort (); | |
12670d88 | 2185 | |
4956d07c MS |
2186 | insn = NEXT_INSN (insn); |
2187 | ||
2188 | /* Look for the matching end. */ | |
2189 | while (! (GET_CODE (insn) == NOTE | |
2190 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)) | |
2191 | { | |
2192 | /* If anything can throw, we can't remove the region. */ | |
2193 | if (delete && can_throw (insn)) | |
2194 | { | |
2195 | delete = 0; | |
2196 | } | |
2197 | ||
2198 | /* Watch out for and handle nested regions. */ | |
2199 | if (GET_CODE (insn) == NOTE | |
2200 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG) | |
2201 | { | |
2202 | insn = scan_region (insn, NOTE_BLOCK_NUMBER (insn), &delete); | |
2203 | } | |
2204 | ||
2205 | insn = NEXT_INSN (insn); | |
2206 | } | |
2207 | ||
2208 | /* The _BEG/_END NOTEs must match and nest. */ | |
2209 | if (NOTE_BLOCK_NUMBER (insn) != n) | |
2210 | abort (); | |
2211 | ||
12670d88 | 2212 | /* If anything in this exception region can throw, we can throw. */ |
4956d07c MS |
2213 | if (! delete) |
2214 | *delete_outer = 0; | |
2215 | else | |
2216 | { | |
2217 | /* Delete the start and end of the region. */ | |
2218 | delete_insn (start); | |
2219 | delete_insn (insn); | |
2220 | ||
9a0d1e1b AM |
2221 | /* We no longer removed labels here, since flow will now remove any |
2222 | handler which cannot be called any more. */ | |
2223 | ||
2224 | #if 0 | |
4956d07c MS |
2225 | /* Only do this part if we have built the exception handler |
2226 | labels. */ | |
2227 | if (exception_handler_labels) | |
2228 | { | |
2229 | rtx x, *prev = &exception_handler_labels; | |
2230 | ||
2231 | /* Find it in the list of handlers. */ | |
2232 | for (x = exception_handler_labels; x; x = XEXP (x, 1)) | |
2233 | { | |
2234 | rtx label = XEXP (x, 0); | |
2235 | if (CODE_LABEL_NUMBER (label) == n) | |
2236 | { | |
2237 | /* If we are the last reference to the handler, | |
2238 | delete it. */ | |
2239 | if (--LABEL_NUSES (label) == 0) | |
2240 | delete_insn (label); | |
2241 | ||
2242 | if (optimize) | |
2243 | { | |
2244 | /* Remove it from the list of exception handler | |
2245 | labels, if we are optimizing. If we are not, then | |
2246 | leave it in the list, as we are not really going to | |
2247 | remove the region. */ | |
2248 | *prev = XEXP (x, 1); | |
2249 | XEXP (x, 1) = 0; | |
2250 | XEXP (x, 0) = 0; | |
2251 | } | |
2252 | ||
2253 | break; | |
2254 | } | |
2255 | prev = &XEXP (x, 1); | |
2256 | } | |
2257 | } | |
9a0d1e1b | 2258 | #endif |
4956d07c MS |
2259 | } |
2260 | return insn; | |
2261 | } | |
2262 | ||
2263 | /* Perform various interesting optimizations for exception handling | |
2264 | code. | |
2265 | ||
12670d88 RK |
2266 | We look for empty exception regions and make them go (away). The |
2267 | jump optimization code will remove the handler if nothing else uses | |
abeeec2a | 2268 | it. */ |
4956d07c MS |
2269 | |
2270 | void | |
2271 | exception_optimize () | |
2272 | { | |
381127e8 | 2273 | rtx insn; |
4956d07c MS |
2274 | int n; |
2275 | ||
12670d88 | 2276 | /* Remove empty regions. */ |
4956d07c MS |
2277 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) |
2278 | { | |
2279 | if (GET_CODE (insn) == NOTE | |
2280 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG) | |
2281 | { | |
27a36778 | 2282 | /* Since scan_region will return the NOTE_INSN_EH_REGION_END |
12670d88 RK |
2283 | insn, we will indirectly skip through all the insns |
2284 | inbetween. We are also guaranteed that the value of insn | |
27a36778 | 2285 | returned will be valid, as otherwise scan_region won't |
abeeec2a | 2286 | return. */ |
4956d07c MS |
2287 | insn = scan_region (insn, NOTE_BLOCK_NUMBER (insn), &n); |
2288 | } | |
2289 | } | |
2290 | } | |
ca55abae JM |
2291 | \f |
2292 | /* Various hooks for the DWARF 2 __throw routine. */ | |
2293 | ||
2294 | /* Do any necessary initialization to access arbitrary stack frames. | |
2295 | On the SPARC, this means flushing the register windows. */ | |
2296 | ||
2297 | void | |
2298 | expand_builtin_unwind_init () | |
2299 | { | |
2300 | /* Set this so all the registers get saved in our frame; we need to be | |
2301 | able to copy the saved values for any registers from frames we unwind. */ | |
2302 | current_function_has_nonlocal_label = 1; | |
2303 | ||
2304 | #ifdef SETUP_FRAME_ADDRESSES | |
2305 | SETUP_FRAME_ADDRESSES (); | |
2306 | #endif | |
2307 | } | |
2308 | ||
2309 | /* Given a value extracted from the return address register or stack slot, | |
2310 | return the actual address encoded in that value. */ | |
2311 | ||
2312 | rtx | |
2313 | expand_builtin_extract_return_addr (addr_tree) | |
2314 | tree addr_tree; | |
2315 | { | |
2316 | rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0); | |
2317 | return eh_outer_context (addr); | |
2318 | } | |
2319 | ||
2320 | /* Given an actual address in addr_tree, do any necessary encoding | |
2321 | and return the value to be stored in the return address register or | |
2322 | stack slot so the epilogue will return to that address. */ | |
2323 | ||
2324 | rtx | |
2325 | expand_builtin_frob_return_addr (addr_tree) | |
2326 | tree addr_tree; | |
2327 | { | |
2328 | rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0); | |
2329 | #ifdef RETURN_ADDR_OFFSET | |
2330 | addr = plus_constant (addr, -RETURN_ADDR_OFFSET); | |
2331 | #endif | |
2332 | return addr; | |
2333 | } | |
2334 | ||
2335 | /* Given an actual address in addr_tree, set the return address register up | |
2336 | so the epilogue will return to that address. If the return address is | |
2337 | not in a register, do nothing. */ | |
2338 | ||
2339 | void | |
2340 | expand_builtin_set_return_addr_reg (addr_tree) | |
2341 | tree addr_tree; | |
2342 | { | |
4f870c04 | 2343 | rtx tmp; |
ca55abae JM |
2344 | rtx ra = expand_builtin_return_addr (BUILT_IN_RETURN_ADDRESS, |
2345 | 0, hard_frame_pointer_rtx); | |
2346 | ||
2347 | if (GET_CODE (ra) != REG || REGNO (ra) >= FIRST_PSEUDO_REGISTER) | |
2348 | return; | |
2349 | ||
4f870c04 JM |
2350 | tmp = force_operand (expand_builtin_frob_return_addr (addr_tree), ra); |
2351 | if (tmp != ra) | |
2352 | emit_move_insn (ra, tmp); | |
ca55abae JM |
2353 | } |
2354 | ||
2355 | /* Choose two registers for communication between the main body of | |
2356 | __throw and the stub for adjusting the stack pointer. The first register | |
2357 | is used to pass the address of the exception handler; the second register | |
2358 | is used to pass the stack pointer offset. | |
2359 | ||
2360 | For register 1 we use the return value register for a void *. | |
2361 | For register 2 we use the static chain register if it exists and is | |
2362 | different from register 1, otherwise some arbitrary call-clobbered | |
2363 | register. */ | |
2364 | ||
2365 | static void | |
2366 | eh_regs (r1, r2, outgoing) | |
2367 | rtx *r1, *r2; | |
2368 | int outgoing; | |
2369 | { | |
2370 | rtx reg1, reg2; | |
2371 | ||
2372 | #ifdef FUNCTION_OUTGOING_VALUE | |
2373 | if (outgoing) | |
2374 | reg1 = FUNCTION_OUTGOING_VALUE (build_pointer_type (void_type_node), | |
2375 | current_function_decl); | |
2376 | else | |
2377 | #endif | |
2378 | reg1 = FUNCTION_VALUE (build_pointer_type (void_type_node), | |
2379 | current_function_decl); | |
2380 | ||
2381 | #ifdef STATIC_CHAIN_REGNUM | |
2382 | if (outgoing) | |
2383 | reg2 = static_chain_incoming_rtx; | |
2384 | else | |
2385 | reg2 = static_chain_rtx; | |
2386 | if (REGNO (reg2) == REGNO (reg1)) | |
2387 | #endif /* STATIC_CHAIN_REGNUM */ | |
2388 | reg2 = NULL_RTX; | |
2389 | ||
2390 | if (reg2 == NULL_RTX) | |
2391 | { | |
2392 | int i; | |
2393 | for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i) | |
2394 | if (call_used_regs[i] && ! fixed_regs[i] && i != REGNO (reg1)) | |
2395 | { | |
38a448ca | 2396 | reg2 = gen_rtx_REG (Pmode, i); |
ca55abae JM |
2397 | break; |
2398 | } | |
2399 | ||
2400 | if (reg2 == NULL_RTX) | |
2401 | abort (); | |
2402 | } | |
2403 | ||
2404 | *r1 = reg1; | |
2405 | *r2 = reg2; | |
2406 | } | |
2407 | ||
9a0d1e1b AM |
2408 | |
2409 | /* Retrieve the register which contains the pointer to the eh_context | |
2410 | structure set the __throw. */ | |
2411 | ||
2412 | rtx | |
2413 | get_reg_for_handler () | |
2414 | { | |
2415 | rtx reg1; | |
2416 | reg1 = FUNCTION_VALUE (build_pointer_type (void_type_node), | |
2417 | current_function_decl); | |
2418 | return reg1; | |
2419 | } | |
2420 | ||
2421 | ||
ca55abae JM |
2422 | /* Emit inside of __throw a stub which adjusts the stack pointer and jumps |
2423 | to the exception handler. __throw will set up the necessary values | |
2424 | and then return to the stub. */ | |
2425 | ||
a1622f83 AM |
2426 | rtx |
2427 | expand_builtin_eh_stub_old () | |
2428 | { | |
2429 | rtx stub_start = gen_label_rtx (); | |
2430 | rtx after_stub = gen_label_rtx (); | |
2431 | rtx handler, offset; | |
2432 | ||
2433 | emit_jump (after_stub); | |
2434 | emit_label (stub_start); | |
2435 | ||
2436 | eh_regs (&handler, &offset, 0); | |
2437 | ||
2438 | adjust_stack (offset); | |
2439 | emit_indirect_jump (handler); | |
2440 | emit_label (after_stub); | |
2441 | return gen_rtx_LABEL_REF (Pmode, stub_start); | |
2442 | } | |
2443 | ||
ca55abae JM |
2444 | rtx |
2445 | expand_builtin_eh_stub () | |
2446 | { | |
2447 | rtx stub_start = gen_label_rtx (); | |
2448 | rtx after_stub = gen_label_rtx (); | |
381127e8 | 2449 | rtx handler, offset; |
a1622f83 | 2450 | rtx jump_to, temp; |
ca55abae JM |
2451 | |
2452 | emit_jump (after_stub); | |
2453 | emit_label (stub_start); | |
2454 | ||
2455 | eh_regs (&handler, &offset, 0); | |
2456 | ||
2457 | adjust_stack (offset); | |
9a0d1e1b AM |
2458 | |
2459 | /* Handler is in fact a pointer to the _eh_context structure, we need | |
2460 | to pick out the handler field (first element), and jump to there, | |
2461 | leaving the pointer to _eh_conext in the same hardware register. */ | |
9a0d1e1b | 2462 | |
a1622f83 AM |
2463 | temp = gen_rtx_MEM (Pmode, handler); |
2464 | MEM_IN_STRUCT_P (temp) = 1; | |
2465 | RTX_UNCHANGING_P (temp) = 1; | |
2466 | emit_insn (gen_rtx_SET (Pmode, offset, temp)); | |
2467 | emit_insn (gen_rtx_USE (Pmode, handler)); | |
9a0d1e1b | 2468 | |
a1622f83 | 2469 | emit_indirect_jump (offset); |
9a0d1e1b | 2470 | |
ca55abae | 2471 | emit_label (after_stub); |
38a448ca | 2472 | return gen_rtx_LABEL_REF (Pmode, stub_start); |
ca55abae JM |
2473 | } |
2474 | ||
2475 | /* Set up the registers for passing the handler address and stack offset | |
2476 | to the stub above. */ | |
2477 | ||
2478 | void | |
2479 | expand_builtin_set_eh_regs (handler, offset) | |
2480 | tree handler, offset; | |
2481 | { | |
2482 | rtx reg1, reg2; | |
2483 | ||
2484 | eh_regs (®1, ®2, 1); | |
2485 | ||
2486 | store_expr (offset, reg2, 0); | |
2487 | store_expr (handler, reg1, 0); | |
2488 | ||
2489 | /* These will be used by the stub. */ | |
38a448ca RH |
2490 | emit_insn (gen_rtx_USE (VOIDmode, reg1)); |
2491 | emit_insn (gen_rtx_USE (VOIDmode, reg2)); | |
ca55abae | 2492 | } |
77d33a84 AM |
2493 | |
2494 | \f | |
2495 | ||
2496 | /* This contains the code required to verify whether arbitrary instructions | |
2497 | are in the same exception region. */ | |
2498 | ||
2499 | static int *insn_eh_region = (int *)0; | |
2500 | static int maximum_uid; | |
2501 | ||
242c13b0 JL |
2502 | static void |
2503 | set_insn_eh_region (first, region_num) | |
77d33a84 AM |
2504 | rtx *first; |
2505 | int region_num; | |
2506 | { | |
2507 | rtx insn; | |
2508 | int rnum; | |
2509 | ||
2510 | for (insn = *first; insn; insn = NEXT_INSN (insn)) | |
2511 | { | |
2512 | if ((GET_CODE (insn) == NOTE) && | |
2513 | (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)) | |
2514 | { | |
2515 | rnum = NOTE_BLOCK_NUMBER (insn); | |
2516 | insn_eh_region[INSN_UID (insn)] = rnum; | |
2517 | insn = NEXT_INSN (insn); | |
2518 | set_insn_eh_region (&insn, rnum); | |
2519 | /* Upon return, insn points to the EH_REGION_END of nested region */ | |
2520 | continue; | |
2521 | } | |
2522 | insn_eh_region[INSN_UID (insn)] = region_num; | |
2523 | if ((GET_CODE (insn) == NOTE) && | |
2524 | (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)) | |
2525 | break; | |
2526 | } | |
2527 | *first = insn; | |
2528 | } | |
2529 | ||
2530 | /* Free the insn table, an make sure it cannot be used again. */ | |
2531 | ||
9a0d1e1b AM |
2532 | void |
2533 | free_insn_eh_region () | |
77d33a84 AM |
2534 | { |
2535 | if (!doing_eh (0)) | |
2536 | return; | |
2537 | ||
2538 | if (insn_eh_region) | |
2539 | { | |
2540 | free (insn_eh_region); | |
2541 | insn_eh_region = (int *)0; | |
2542 | } | |
2543 | } | |
2544 | ||
2545 | /* Initialize the table. max_uid must be calculated and handed into | |
2546 | this routine. If it is unavailable, passing a value of 0 will | |
2547 | cause this routine to calculate it as well. */ | |
2548 | ||
9a0d1e1b AM |
2549 | void |
2550 | init_insn_eh_region (first, max_uid) | |
77d33a84 AM |
2551 | rtx first; |
2552 | int max_uid; | |
2553 | { | |
2554 | rtx insn; | |
2555 | ||
2556 | if (!doing_eh (0)) | |
2557 | return; | |
2558 | ||
2559 | if (insn_eh_region) | |
2560 | free_insn_eh_region(); | |
2561 | ||
2562 | if (max_uid == 0) | |
2563 | for (insn = first; insn; insn = NEXT_INSN (insn)) | |
2564 | if (INSN_UID (insn) > max_uid) /* find largest UID */ | |
2565 | max_uid = INSN_UID (insn); | |
2566 | ||
2567 | maximum_uid = max_uid; | |
2568 | insn_eh_region = (int *) malloc ((max_uid + 1) * sizeof (int)); | |
2569 | insn = first; | |
2570 | set_insn_eh_region (&insn, 0); | |
2571 | } | |
2572 | ||
2573 | ||
2574 | /* Check whether 2 instructions are within the same region. */ | |
2575 | ||
9a0d1e1b AM |
2576 | int |
2577 | in_same_eh_region (insn1, insn2) | |
2578 | rtx insn1, insn2; | |
77d33a84 AM |
2579 | { |
2580 | int ret, uid1, uid2; | |
2581 | ||
2582 | /* If no exceptions, instructions are always in same region. */ | |
2583 | if (!doing_eh (0)) | |
2584 | return 1; | |
2585 | ||
2586 | /* If the table isn't allocated, assume the worst. */ | |
2587 | if (!insn_eh_region) | |
2588 | return 0; | |
2589 | ||
2590 | uid1 = INSN_UID (insn1); | |
2591 | uid2 = INSN_UID (insn2); | |
2592 | ||
2593 | /* if instructions have been allocated beyond the end, either | |
2594 | the table is out of date, or this is a late addition, or | |
2595 | something... Assume the worst. */ | |
2596 | if (uid1 > maximum_uid || uid2 > maximum_uid) | |
2597 | return 0; | |
2598 | ||
2599 | ret = (insn_eh_region[uid1] == insn_eh_region[uid2]); | |
2600 | return ret; | |
2601 | } | |
2602 |