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12670d88 | 1 | /* Implements exception handling. |
e9a25f70 | 2 | Copyright (C) 1989, 92-96, 1997 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 | |
100 | __register_frame. On other targets, the information for each | |
d1485032 | 101 | translation unit is registered from the file generated by collect2. |
ca55abae JM |
102 | __register_frame is defined in frame.c, and is responsible for |
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 |
ca55abae JM |
110 | -fexceptions by the the C++ frontend. Before __throw is invoked, |
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" |
4956d07c MS |
393 | #include <stdio.h> |
394 | #include "rtl.h" | |
395 | #include "tree.h" | |
396 | #include "flags.h" | |
397 | #include "except.h" | |
398 | #include "function.h" | |
399 | #include "insn-flags.h" | |
400 | #include "expr.h" | |
401 | #include "insn-codes.h" | |
402 | #include "regs.h" | |
403 | #include "hard-reg-set.h" | |
404 | #include "insn-config.h" | |
405 | #include "recog.h" | |
406 | #include "output.h" | |
407 | ||
27a36778 MS |
408 | /* One to use setjmp/longjmp method of generating code for exception |
409 | handling. */ | |
410 | ||
d1485032 | 411 | int exceptions_via_longjmp = 2; |
27a36778 MS |
412 | |
413 | /* One to enable asynchronous exception support. */ | |
414 | ||
415 | int asynchronous_exceptions = 0; | |
416 | ||
417 | /* One to protect cleanup actions with a handler that calls | |
418 | __terminate, zero otherwise. */ | |
419 | ||
e701eb4d | 420 | int protect_cleanup_actions_with_terminate; |
27a36778 | 421 | |
12670d88 | 422 | /* A list of labels used for exception handlers. Created by |
4956d07c MS |
423 | find_exception_handler_labels for the optimization passes. */ |
424 | ||
425 | rtx exception_handler_labels; | |
426 | ||
12670d88 RK |
427 | /* Nonzero means that __throw was invoked. |
428 | ||
429 | This is used by the C++ frontend to know if code needs to be emitted | |
430 | for __throw or not. */ | |
4956d07c MS |
431 | |
432 | int throw_used; | |
433 | ||
154bba13 TT |
434 | /* The EH context. Nonzero if the function has already |
435 | fetched a pointer to the EH context for exception handling. */ | |
27a36778 | 436 | |
154bba13 | 437 | rtx current_function_ehc; |
27a36778 | 438 | |
956d6950 | 439 | /* A stack used for keeping track of the currently active exception |
12670d88 | 440 | handling region. As each exception region is started, an entry |
4956d07c MS |
441 | describing the region is pushed onto this stack. The current |
442 | region can be found by looking at the top of the stack, and as we | |
12670d88 RK |
443 | exit regions, the corresponding entries are popped. |
444 | ||
27a36778 | 445 | Entries cannot overlap; they can be nested. So there is only one |
12670d88 RK |
446 | entry at most that corresponds to the current instruction, and that |
447 | is the entry on the top of the stack. */ | |
4956d07c | 448 | |
27a36778 | 449 | static struct eh_stack ehstack; |
4956d07c | 450 | |
12670d88 RK |
451 | /* A queue used for tracking which exception regions have closed but |
452 | whose handlers have not yet been expanded. Regions are emitted in | |
453 | groups in an attempt to improve paging performance. | |
454 | ||
455 | As we exit a region, we enqueue a new entry. The entries are then | |
27a36778 | 456 | dequeued during expand_leftover_cleanups and expand_start_all_catch, |
12670d88 RK |
457 | |
458 | We should redo things so that we either take RTL for the handler, | |
459 | or we expand the handler expressed as a tree immediately at region | |
460 | end time. */ | |
4956d07c | 461 | |
27a36778 | 462 | static struct eh_queue ehqueue; |
4956d07c | 463 | |
12670d88 | 464 | /* Insns for all of the exception handlers for the current function. |
abeeec2a | 465 | They are currently emitted by the frontend code. */ |
4956d07c MS |
466 | |
467 | rtx catch_clauses; | |
468 | ||
12670d88 RK |
469 | /* A TREE_CHAINed list of handlers for regions that are not yet |
470 | closed. The TREE_VALUE of each entry contains the handler for the | |
abeeec2a | 471 | corresponding entry on the ehstack. */ |
4956d07c | 472 | |
12670d88 | 473 | static tree protect_list; |
4956d07c MS |
474 | |
475 | /* Stacks to keep track of various labels. */ | |
476 | ||
12670d88 RK |
477 | /* Keeps track of the label to resume to should one want to resume |
478 | normal control flow out of a handler (instead of, say, returning to | |
1418bb67 | 479 | the caller of the current function or exiting the program). */ |
4956d07c MS |
480 | |
481 | struct label_node *caught_return_label_stack = NULL; | |
482 | ||
956d6950 JL |
483 | /* Keeps track of the label used as the context of a throw to rethrow an |
484 | exception to the outer exception region. */ | |
485 | ||
486 | struct label_node *outer_context_label_stack = NULL; | |
487 | ||
12670d88 | 488 | /* A random data area for the front end's own use. */ |
4956d07c MS |
489 | |
490 | struct label_node *false_label_stack = NULL; | |
491 | ||
4956d07c | 492 | rtx expand_builtin_return_addr PROTO((enum built_in_function, int, rtx)); |
e701eb4d JM |
493 | static void expand_rethrow PROTO((rtx)); |
494 | ||
4956d07c MS |
495 | \f |
496 | /* Various support routines to manipulate the various data structures | |
497 | used by the exception handling code. */ | |
498 | ||
499 | /* Push a label entry onto the given STACK. */ | |
500 | ||
501 | void | |
502 | push_label_entry (stack, rlabel, tlabel) | |
503 | struct label_node **stack; | |
504 | rtx rlabel; | |
505 | tree tlabel; | |
506 | { | |
507 | struct label_node *newnode | |
508 | = (struct label_node *) xmalloc (sizeof (struct label_node)); | |
509 | ||
510 | if (rlabel) | |
511 | newnode->u.rlabel = rlabel; | |
512 | else | |
513 | newnode->u.tlabel = tlabel; | |
514 | newnode->chain = *stack; | |
515 | *stack = newnode; | |
516 | } | |
517 | ||
518 | /* Pop a label entry from the given STACK. */ | |
519 | ||
520 | rtx | |
521 | pop_label_entry (stack) | |
522 | struct label_node **stack; | |
523 | { | |
524 | rtx label; | |
525 | struct label_node *tempnode; | |
526 | ||
527 | if (! *stack) | |
528 | return NULL_RTX; | |
529 | ||
530 | tempnode = *stack; | |
531 | label = tempnode->u.rlabel; | |
532 | *stack = (*stack)->chain; | |
533 | free (tempnode); | |
534 | ||
535 | return label; | |
536 | } | |
537 | ||
538 | /* Return the top element of the given STACK. */ | |
539 | ||
540 | tree | |
541 | top_label_entry (stack) | |
542 | struct label_node **stack; | |
543 | { | |
544 | if (! *stack) | |
545 | return NULL_TREE; | |
546 | ||
547 | return (*stack)->u.tlabel; | |
548 | } | |
549 | ||
12670d88 | 550 | /* Make a copy of ENTRY using xmalloc to allocate the space. */ |
4956d07c MS |
551 | |
552 | static struct eh_entry * | |
553 | copy_eh_entry (entry) | |
554 | struct eh_entry *entry; | |
555 | { | |
556 | struct eh_entry *newentry; | |
557 | ||
558 | newentry = (struct eh_entry *) xmalloc (sizeof (struct eh_entry)); | |
559 | bcopy ((char *) entry, (char *) newentry, sizeof (struct eh_entry)); | |
560 | ||
561 | return newentry; | |
562 | } | |
563 | ||
478b0752 | 564 | /* Push a new eh_node entry onto STACK. */ |
4956d07c | 565 | |
478b0752 | 566 | static void |
4956d07c MS |
567 | push_eh_entry (stack) |
568 | struct eh_stack *stack; | |
569 | { | |
570 | struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node)); | |
571 | struct eh_entry *entry = (struct eh_entry *) xmalloc (sizeof (struct eh_entry)); | |
572 | ||
478b0752 | 573 | entry->outer_context = gen_label_rtx (); |
4956d07c MS |
574 | entry->exception_handler_label = gen_label_rtx (); |
575 | entry->finalization = NULL_TREE; | |
576 | ||
577 | node->entry = entry; | |
578 | node->chain = stack->top; | |
579 | stack->top = node; | |
4956d07c MS |
580 | } |
581 | ||
582 | /* Pop an entry from the given STACK. */ | |
583 | ||
584 | static struct eh_entry * | |
585 | pop_eh_entry (stack) | |
586 | struct eh_stack *stack; | |
587 | { | |
588 | struct eh_node *tempnode; | |
589 | struct eh_entry *tempentry; | |
590 | ||
591 | tempnode = stack->top; | |
592 | tempentry = tempnode->entry; | |
593 | stack->top = stack->top->chain; | |
594 | free (tempnode); | |
595 | ||
596 | return tempentry; | |
597 | } | |
598 | ||
599 | /* Enqueue an ENTRY onto the given QUEUE. */ | |
600 | ||
601 | static void | |
602 | enqueue_eh_entry (queue, entry) | |
603 | struct eh_queue *queue; | |
604 | struct eh_entry *entry; | |
605 | { | |
606 | struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node)); | |
607 | ||
608 | node->entry = entry; | |
609 | node->chain = NULL; | |
610 | ||
611 | if (queue->head == NULL) | |
612 | { | |
613 | queue->head = node; | |
614 | } | |
615 | else | |
616 | { | |
617 | queue->tail->chain = node; | |
618 | } | |
619 | queue->tail = node; | |
620 | } | |
621 | ||
622 | /* Dequeue an entry from the given QUEUE. */ | |
623 | ||
624 | static struct eh_entry * | |
625 | dequeue_eh_entry (queue) | |
626 | struct eh_queue *queue; | |
627 | { | |
628 | struct eh_node *tempnode; | |
629 | struct eh_entry *tempentry; | |
630 | ||
631 | if (queue->head == NULL) | |
632 | return NULL; | |
633 | ||
634 | tempnode = queue->head; | |
635 | queue->head = queue->head->chain; | |
636 | ||
637 | tempentry = tempnode->entry; | |
638 | free (tempnode); | |
639 | ||
640 | return tempentry; | |
641 | } | |
642 | \f | |
643 | /* Routine to see if exception exception handling is turned on. | |
644 | DO_WARN is non-zero if we want to inform the user that exception | |
12670d88 RK |
645 | handling is turned off. |
646 | ||
647 | This is used to ensure that -fexceptions has been specified if the | |
abeeec2a | 648 | compiler tries to use any exception-specific functions. */ |
4956d07c MS |
649 | |
650 | int | |
651 | doing_eh (do_warn) | |
652 | int do_warn; | |
653 | { | |
654 | if (! flag_exceptions) | |
655 | { | |
656 | static int warned = 0; | |
657 | if (! warned && do_warn) | |
658 | { | |
659 | error ("exception handling disabled, use -fexceptions to enable"); | |
660 | warned = 1; | |
661 | } | |
662 | return 0; | |
663 | } | |
664 | return 1; | |
665 | } | |
666 | ||
12670d88 | 667 | /* Given a return address in ADDR, determine the address we should use |
abeeec2a | 668 | to find the corresponding EH region. */ |
4956d07c MS |
669 | |
670 | rtx | |
671 | eh_outer_context (addr) | |
672 | rtx addr; | |
673 | { | |
674 | /* First mask out any unwanted bits. */ | |
675 | #ifdef MASK_RETURN_ADDR | |
ca55abae | 676 | expand_and (addr, MASK_RETURN_ADDR, addr); |
4956d07c MS |
677 | #endif |
678 | ||
ca55abae JM |
679 | /* Then adjust to find the real return address. */ |
680 | #if defined (RETURN_ADDR_OFFSET) | |
681 | addr = plus_constant (addr, RETURN_ADDR_OFFSET); | |
4956d07c MS |
682 | #endif |
683 | ||
684 | return addr; | |
685 | } | |
686 | ||
27a36778 MS |
687 | /* Start a new exception region for a region of code that has a |
688 | cleanup action and push the HANDLER for the region onto | |
689 | protect_list. All of the regions created with add_partial_entry | |
690 | will be ended when end_protect_partials is invoked. */ | |
12670d88 RK |
691 | |
692 | void | |
693 | add_partial_entry (handler) | |
694 | tree handler; | |
695 | { | |
696 | expand_eh_region_start (); | |
697 | ||
abeeec2a | 698 | /* Make sure the entry is on the correct obstack. */ |
12670d88 RK |
699 | push_obstacks_nochange (); |
700 | resume_temporary_allocation (); | |
27a36778 MS |
701 | |
702 | /* Because this is a cleanup action, we may have to protect the handler | |
703 | with __terminate. */ | |
704 | handler = protect_with_terminate (handler); | |
705 | ||
12670d88 RK |
706 | protect_list = tree_cons (NULL_TREE, handler, protect_list); |
707 | pop_obstacks (); | |
708 | } | |
709 | ||
100d81d4 | 710 | /* Emit code to get EH context to current function. */ |
27a36778 | 711 | |
154bba13 | 712 | static rtx |
01eb7f9a | 713 | call_get_eh_context () |
27a36778 | 714 | { |
bb727b5a JM |
715 | static tree fn; |
716 | tree expr; | |
717 | ||
718 | if (fn == NULL_TREE) | |
719 | { | |
720 | tree fntype; | |
154bba13 | 721 | fn = get_identifier ("__get_eh_context"); |
bb727b5a JM |
722 | push_obstacks_nochange (); |
723 | end_temporary_allocation (); | |
724 | fntype = build_pointer_type (build_pointer_type | |
725 | (build_pointer_type (void_type_node))); | |
726 | fntype = build_function_type (fntype, NULL_TREE); | |
727 | fn = build_decl (FUNCTION_DECL, fn, fntype); | |
728 | DECL_EXTERNAL (fn) = 1; | |
729 | TREE_PUBLIC (fn) = 1; | |
730 | DECL_ARTIFICIAL (fn) = 1; | |
731 | TREE_READONLY (fn) = 1; | |
732 | make_decl_rtl (fn, NULL_PTR, 1); | |
733 | assemble_external (fn); | |
734 | pop_obstacks (); | |
735 | } | |
736 | ||
737 | expr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (fn)), fn); | |
738 | expr = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (fn)), | |
739 | expr, NULL_TREE, NULL_TREE); | |
740 | TREE_SIDE_EFFECTS (expr) = 1; | |
bb727b5a | 741 | |
100d81d4 | 742 | return copy_to_reg (expand_expr (expr, NULL_RTX, VOIDmode, 0)); |
154bba13 TT |
743 | } |
744 | ||
745 | /* Get a reference to the EH context. | |
746 | We will only generate a register for the current function EH context here, | |
747 | and emit a USE insn to mark that this is a EH context register. | |
748 | ||
749 | Later, emit_eh_context will emit needed call to __get_eh_context | |
750 | in libgcc2, and copy the value to the register we have generated. */ | |
751 | ||
752 | rtx | |
01eb7f9a | 753 | get_eh_context () |
154bba13 TT |
754 | { |
755 | if (current_function_ehc == 0) | |
756 | { | |
757 | rtx insn; | |
758 | ||
759 | current_function_ehc = gen_reg_rtx (Pmode); | |
760 | ||
761 | insn = gen_rtx (USE, | |
762 | GET_MODE (current_function_ehc), | |
0776059e | 763 | current_function_ehc); |
154bba13 TT |
764 | insn = emit_insn_before (insn, get_first_nonparm_insn ()); |
765 | ||
766 | REG_NOTES (insn) | |
767 | = gen_rtx (EXPR_LIST, | |
0776059e | 768 | REG_EH_CONTEXT, current_function_ehc, |
154bba13 TT |
769 | REG_NOTES (insn)); |
770 | } | |
771 | return current_function_ehc; | |
772 | } | |
773 | ||
154bba13 TT |
774 | /* Get a reference to the dynamic handler chain. It points to the |
775 | pointer to the next element in the dynamic handler chain. It ends | |
776 | when there are no more elements in the dynamic handler chain, when | |
777 | the value is &top_elt from libgcc2.c. Immediately after the | |
778 | pointer, is an area suitable for setjmp/longjmp when | |
779 | DONT_USE_BUILTIN_SETJMP is defined, and an area suitable for | |
780 | __builtin_setjmp/__builtin_longjmp when DONT_USE_BUILTIN_SETJMP | |
781 | isn't defined. */ | |
782 | ||
783 | rtx | |
784 | get_dynamic_handler_chain () | |
785 | { | |
786 | rtx ehc, dhc, result; | |
787 | ||
01eb7f9a | 788 | ehc = get_eh_context (); |
154bba13 TT |
789 | dhc = ehc; |
790 | ||
791 | result = copy_to_reg (dhc); | |
792 | ||
793 | /* We don't want a copy of the dcc, but rather, the single dcc. */ | |
794 | return gen_rtx (MEM, Pmode, result); | |
27a36778 MS |
795 | } |
796 | ||
797 | /* Get a reference to the dynamic cleanup chain. It points to the | |
798 | pointer to the next element in the dynamic cleanup chain. | |
799 | Immediately after the pointer, are two Pmode variables, one for a | |
800 | pointer to a function that performs the cleanup action, and the | |
801 | second, the argument to pass to that function. */ | |
802 | ||
803 | rtx | |
804 | get_dynamic_cleanup_chain () | |
805 | { | |
154bba13 | 806 | rtx dhc, dcc, result; |
27a36778 MS |
807 | |
808 | dhc = get_dynamic_handler_chain (); | |
809 | dcc = plus_constant (dhc, GET_MODE_SIZE (Pmode)); | |
810 | ||
154bba13 | 811 | result = copy_to_reg (dcc); |
27a36778 MS |
812 | |
813 | /* We don't want a copy of the dcc, but rather, the single dcc. */ | |
154bba13 TT |
814 | return gen_rtx (MEM, Pmode, result); |
815 | } | |
816 | ||
27a36778 MS |
817 | /* Generate code to evaluate X and jump to LABEL if the value is nonzero. |
818 | LABEL is an rtx of code CODE_LABEL, in this function. */ | |
819 | ||
820 | void | |
821 | jumpif_rtx (x, label) | |
822 | rtx x; | |
823 | rtx label; | |
824 | { | |
825 | jumpif (make_tree (type_for_mode (GET_MODE (x), 0), x), label); | |
826 | } | |
827 | ||
828 | /* Generate code to evaluate X and jump to LABEL if the value is zero. | |
829 | LABEL is an rtx of code CODE_LABEL, in this function. */ | |
830 | ||
831 | void | |
832 | jumpifnot_rtx (x, label) | |
833 | rtx x; | |
834 | rtx label; | |
835 | { | |
836 | jumpifnot (make_tree (type_for_mode (GET_MODE (x), 0), x), label); | |
837 | } | |
838 | ||
839 | /* Start a dynamic cleanup on the EH runtime dynamic cleanup stack. | |
840 | We just need to create an element for the cleanup list, and push it | |
841 | into the chain. | |
842 | ||
843 | A dynamic cleanup is a cleanup action implied by the presence of an | |
844 | element on the EH runtime dynamic cleanup stack that is to be | |
845 | performed when an exception is thrown. The cleanup action is | |
846 | performed by __sjthrow when an exception is thrown. Only certain | |
847 | actions can be optimized into dynamic cleanup actions. For the | |
848 | restrictions on what actions can be performed using this routine, | |
849 | see expand_eh_region_start_tree. */ | |
850 | ||
851 | static void | |
852 | start_dynamic_cleanup (func, arg) | |
853 | tree func; | |
854 | tree arg; | |
855 | { | |
856 | rtx dhc, dcc; | |
857 | rtx new_func, new_arg; | |
858 | rtx x, buf; | |
859 | int size; | |
860 | ||
861 | /* We allocate enough room for a pointer to the function, and | |
862 | one argument. */ | |
863 | size = 2; | |
864 | ||
865 | /* XXX, FIXME: The stack space allocated this way is too long lived, | |
866 | but there is no allocation routine that allocates at the level of | |
867 | the last binding contour. */ | |
868 | buf = assign_stack_local (BLKmode, | |
869 | GET_MODE_SIZE (Pmode)*(size+1), | |
870 | 0); | |
871 | ||
872 | buf = change_address (buf, Pmode, NULL_RTX); | |
873 | ||
874 | /* Store dcc into the first word of the newly allocated buffer. */ | |
875 | ||
876 | dcc = get_dynamic_cleanup_chain (); | |
877 | emit_move_insn (buf, dcc); | |
878 | ||
879 | /* Store func and arg into the cleanup list element. */ | |
880 | ||
881 | new_func = gen_rtx (MEM, Pmode, plus_constant (XEXP (buf, 0), | |
882 | GET_MODE_SIZE (Pmode))); | |
883 | new_arg = gen_rtx (MEM, Pmode, plus_constant (XEXP (buf, 0), | |
884 | GET_MODE_SIZE (Pmode)*2)); | |
885 | x = expand_expr (func, new_func, Pmode, 0); | |
886 | if (x != new_func) | |
887 | emit_move_insn (new_func, x); | |
888 | ||
889 | x = expand_expr (arg, new_arg, Pmode, 0); | |
890 | if (x != new_arg) | |
891 | emit_move_insn (new_arg, x); | |
892 | ||
893 | /* Update the cleanup chain. */ | |
894 | ||
895 | emit_move_insn (dcc, XEXP (buf, 0)); | |
896 | } | |
897 | ||
898 | /* Emit RTL to start a dynamic handler on the EH runtime dynamic | |
899 | handler stack. This should only be used by expand_eh_region_start | |
900 | or expand_eh_region_start_tree. */ | |
901 | ||
902 | static void | |
903 | start_dynamic_handler () | |
904 | { | |
905 | rtx dhc, dcc; | |
6e6a07d2 | 906 | rtx x, arg, buf; |
27a36778 MS |
907 | int size; |
908 | ||
6e6a07d2 | 909 | #ifndef DONT_USE_BUILTIN_SETJMP |
27a36778 MS |
910 | /* The number of Pmode words for the setjmp buffer, when using the |
911 | builtin setjmp/longjmp, see expand_builtin, case | |
912 | BUILT_IN_LONGJMP. */ | |
913 | size = 5; | |
914 | #else | |
915 | #ifdef JMP_BUF_SIZE | |
916 | size = JMP_BUF_SIZE; | |
917 | #else | |
918 | /* Should be large enough for most systems, if it is not, | |
919 | JMP_BUF_SIZE should be defined with the proper value. It will | |
920 | also tend to be larger than necessary for most systems, a more | |
921 | optimal port will define JMP_BUF_SIZE. */ | |
922 | size = FIRST_PSEUDO_REGISTER+2; | |
923 | #endif | |
924 | #endif | |
925 | /* XXX, FIXME: The stack space allocated this way is too long lived, | |
926 | but there is no allocation routine that allocates at the level of | |
927 | the last binding contour. */ | |
928 | arg = assign_stack_local (BLKmode, | |
929 | GET_MODE_SIZE (Pmode)*(size+1), | |
930 | 0); | |
931 | ||
932 | arg = change_address (arg, Pmode, NULL_RTX); | |
933 | ||
934 | /* Store dhc into the first word of the newly allocated buffer. */ | |
935 | ||
936 | dhc = get_dynamic_handler_chain (); | |
937 | dcc = gen_rtx (MEM, Pmode, plus_constant (XEXP (arg, 0), | |
938 | GET_MODE_SIZE (Pmode))); | |
939 | emit_move_insn (arg, dhc); | |
940 | ||
941 | /* Zero out the start of the cleanup chain. */ | |
942 | emit_move_insn (dcc, const0_rtx); | |
943 | ||
944 | /* The jmpbuf starts two words into the area allocated. */ | |
6e6a07d2 | 945 | buf = plus_constant (XEXP (arg, 0), GET_MODE_SIZE (Pmode)*2); |
27a36778 | 946 | |
6e6a07d2 | 947 | #ifdef DONT_USE_BUILTIN_SETJMP |
27a36778 | 948 | x = emit_library_call_value (setjmp_libfunc, NULL_RTX, 1, SImode, 1, |
6e6a07d2 MS |
949 | buf, Pmode); |
950 | #else | |
951 | x = expand_builtin_setjmp (buf, NULL_RTX); | |
952 | #endif | |
27a36778 MS |
953 | |
954 | /* If we come back here for a catch, transfer control to the | |
955 | handler. */ | |
956 | ||
957 | jumpif_rtx (x, ehstack.top->entry->exception_handler_label); | |
958 | ||
959 | /* We are committed to this, so update the handler chain. */ | |
960 | ||
961 | emit_move_insn (dhc, XEXP (arg, 0)); | |
962 | } | |
963 | ||
964 | /* Start an exception handling region for the given cleanup action. | |
12670d88 | 965 | All instructions emitted after this point are considered to be part |
27a36778 MS |
966 | of the region until expand_eh_region_end is invoked. CLEANUP is |
967 | the cleanup action to perform. The return value is true if the | |
968 | exception region was optimized away. If that case, | |
969 | expand_eh_region_end does not need to be called for this cleanup, | |
970 | nor should it be. | |
971 | ||
972 | This routine notices one particular common case in C++ code | |
973 | generation, and optimizes it so as to not need the exception | |
974 | region. It works by creating a dynamic cleanup action, instead of | |
975 | of a using an exception region. */ | |
976 | ||
977 | int | |
4c581243 MS |
978 | expand_eh_region_start_tree (decl, cleanup) |
979 | tree decl; | |
27a36778 MS |
980 | tree cleanup; |
981 | { | |
982 | rtx note; | |
983 | ||
984 | /* This is the old code. */ | |
985 | if (! doing_eh (0)) | |
986 | return 0; | |
987 | ||
988 | /* The optimization only applies to actions protected with | |
989 | terminate, and only applies if we are using the setjmp/longjmp | |
990 | codegen method. */ | |
991 | if (exceptions_via_longjmp | |
992 | && protect_cleanup_actions_with_terminate) | |
993 | { | |
994 | tree func, arg; | |
995 | tree args; | |
996 | ||
997 | /* Ignore any UNSAVE_EXPR. */ | |
998 | if (TREE_CODE (cleanup) == UNSAVE_EXPR) | |
999 | cleanup = TREE_OPERAND (cleanup, 0); | |
1000 | ||
1001 | /* Further, it only applies if the action is a call, if there | |
1002 | are 2 arguments, and if the second argument is 2. */ | |
1003 | ||
1004 | if (TREE_CODE (cleanup) == CALL_EXPR | |
1005 | && (args = TREE_OPERAND (cleanup, 1)) | |
1006 | && (func = TREE_OPERAND (cleanup, 0)) | |
1007 | && (arg = TREE_VALUE (args)) | |
1008 | && (args = TREE_CHAIN (args)) | |
1009 | ||
1010 | /* is the second argument 2? */ | |
1011 | && TREE_CODE (TREE_VALUE (args)) == INTEGER_CST | |
1012 | && TREE_INT_CST_LOW (TREE_VALUE (args)) == 2 | |
1013 | && TREE_INT_CST_HIGH (TREE_VALUE (args)) == 0 | |
1014 | ||
1015 | /* Make sure there are no other arguments. */ | |
1016 | && TREE_CHAIN (args) == NULL_TREE) | |
1017 | { | |
1018 | /* Arrange for returns and gotos to pop the entry we make on the | |
1019 | dynamic cleanup stack. */ | |
4c581243 | 1020 | expand_dcc_cleanup (decl); |
27a36778 MS |
1021 | start_dynamic_cleanup (func, arg); |
1022 | return 1; | |
1023 | } | |
1024 | } | |
1025 | ||
4c581243 | 1026 | expand_eh_region_start_for_decl (decl); |
9762d48d | 1027 | ehstack.top->entry->finalization = cleanup; |
27a36778 MS |
1028 | |
1029 | return 0; | |
1030 | } | |
1031 | ||
4c581243 MS |
1032 | /* Just like expand_eh_region_start, except if a cleanup action is |
1033 | entered on the cleanup chain, the TREE_PURPOSE of the element put | |
1034 | on the chain is DECL. DECL should be the associated VAR_DECL, if | |
1035 | any, otherwise it should be NULL_TREE. */ | |
4956d07c MS |
1036 | |
1037 | void | |
4c581243 MS |
1038 | expand_eh_region_start_for_decl (decl) |
1039 | tree decl; | |
4956d07c MS |
1040 | { |
1041 | rtx note; | |
1042 | ||
1043 | /* This is the old code. */ | |
1044 | if (! doing_eh (0)) | |
1045 | return; | |
1046 | ||
27a36778 MS |
1047 | if (exceptions_via_longjmp) |
1048 | { | |
1049 | /* We need a new block to record the start and end of the | |
1050 | dynamic handler chain. We could always do this, but we | |
1051 | really want to permit jumping into such a block, and we want | |
1052 | to avoid any errors or performance impact in the SJ EH code | |
1053 | for now. */ | |
1054 | expand_start_bindings (0); | |
1055 | ||
1056 | /* But we don't need or want a new temporary level. */ | |
1057 | pop_temp_slots (); | |
1058 | ||
1059 | /* Mark this block as created by expand_eh_region_start. This | |
1060 | is so that we can pop the block with expand_end_bindings | |
1061 | automatically. */ | |
1062 | mark_block_as_eh_region (); | |
1063 | ||
1064 | /* Arrange for returns and gotos to pop the entry we make on the | |
1065 | dynamic handler stack. */ | |
4c581243 | 1066 | expand_dhc_cleanup (decl); |
27a36778 | 1067 | } |
4956d07c | 1068 | |
478b0752 | 1069 | push_eh_entry (&ehstack); |
9ad8a5f0 MS |
1070 | note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_BEG); |
1071 | NOTE_BLOCK_NUMBER (note) | |
1072 | = CODE_LABEL_NUMBER (ehstack.top->entry->exception_handler_label); | |
27a36778 MS |
1073 | if (exceptions_via_longjmp) |
1074 | start_dynamic_handler (); | |
4956d07c MS |
1075 | } |
1076 | ||
4c581243 MS |
1077 | /* Start an exception handling region. All instructions emitted after |
1078 | this point are considered to be part of the region until | |
1079 | expand_eh_region_end is invoked. */ | |
1080 | ||
1081 | void | |
1082 | expand_eh_region_start () | |
1083 | { | |
1084 | expand_eh_region_start_for_decl (NULL_TREE); | |
1085 | } | |
1086 | ||
27a36778 MS |
1087 | /* End an exception handling region. The information about the region |
1088 | is found on the top of ehstack. | |
12670d88 RK |
1089 | |
1090 | HANDLER is either the cleanup for the exception region, or if we're | |
1091 | marking the end of a try block, HANDLER is integer_zero_node. | |
1092 | ||
27a36778 | 1093 | HANDLER will be transformed to rtl when expand_leftover_cleanups |
abeeec2a | 1094 | is invoked. */ |
4956d07c MS |
1095 | |
1096 | void | |
1097 | expand_eh_region_end (handler) | |
1098 | tree handler; | |
1099 | { | |
4956d07c | 1100 | struct eh_entry *entry; |
9ad8a5f0 | 1101 | rtx note; |
4956d07c MS |
1102 | |
1103 | if (! doing_eh (0)) | |
1104 | return; | |
1105 | ||
1106 | entry = pop_eh_entry (&ehstack); | |
1107 | ||
9ad8a5f0 MS |
1108 | note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_END); |
1109 | NOTE_BLOCK_NUMBER (note) | |
1110 | = CODE_LABEL_NUMBER (entry->exception_handler_label); | |
e701eb4d JM |
1111 | if (exceptions_via_longjmp == 0 |
1112 | /* We share outer_context between regions; only emit it once. */ | |
1113 | && INSN_UID (entry->outer_context) == 0) | |
27a36778 | 1114 | { |
478b0752 | 1115 | rtx label; |
4956d07c | 1116 | |
478b0752 MS |
1117 | label = gen_label_rtx (); |
1118 | emit_jump (label); | |
1119 | ||
1120 | /* Emit a label marking the end of this exception region that | |
1121 | is used for rethrowing into the outer context. */ | |
1122 | emit_label (entry->outer_context); | |
e701eb4d | 1123 | expand_internal_throw (); |
4956d07c | 1124 | |
478b0752 | 1125 | emit_label (label); |
27a36778 | 1126 | } |
4956d07c MS |
1127 | |
1128 | entry->finalization = handler; | |
1129 | ||
1130 | enqueue_eh_entry (&ehqueue, entry); | |
1131 | ||
27a36778 MS |
1132 | /* If we have already started ending the bindings, don't recurse. |
1133 | This only happens when exceptions_via_longjmp is true. */ | |
1134 | if (is_eh_region ()) | |
1135 | { | |
1136 | /* Because we don't need or want a new temporary level and | |
1137 | because we didn't create one in expand_eh_region_start, | |
1138 | create a fake one now to avoid removing one in | |
1139 | expand_end_bindings. */ | |
1140 | push_temp_slots (); | |
1141 | ||
1142 | mark_block_as_not_eh_region (); | |
1143 | ||
1144 | /* Maybe do this to prevent jumping in and so on... */ | |
1145 | expand_end_bindings (NULL_TREE, 0, 0); | |
1146 | } | |
4956d07c MS |
1147 | } |
1148 | ||
9762d48d JM |
1149 | /* End the EH region for a goto fixup. We only need them in the region-based |
1150 | EH scheme. */ | |
1151 | ||
1152 | void | |
1153 | expand_fixup_region_start () | |
1154 | { | |
1155 | if (! doing_eh (0) || exceptions_via_longjmp) | |
1156 | return; | |
1157 | ||
1158 | expand_eh_region_start (); | |
1159 | } | |
1160 | ||
1161 | /* End the EH region for a goto fixup. CLEANUP is the cleanup we just | |
1162 | expanded; to avoid running it twice if it throws, we look through the | |
1163 | ehqueue for a matching region and rethrow from its outer_context. */ | |
1164 | ||
1165 | void | |
1166 | expand_fixup_region_end (cleanup) | |
1167 | tree cleanup; | |
1168 | { | |
9762d48d | 1169 | struct eh_node *node; |
9762d48d JM |
1170 | |
1171 | if (! doing_eh (0) || exceptions_via_longjmp) | |
1172 | return; | |
1173 | ||
1174 | for (node = ehstack.top; node && node->entry->finalization != cleanup; ) | |
1175 | node = node->chain; | |
1176 | if (node == 0) | |
1177 | for (node = ehqueue.head; node && node->entry->finalization != cleanup; ) | |
1178 | node = node->chain; | |
1179 | if (node == 0) | |
1180 | abort (); | |
1181 | ||
e701eb4d | 1182 | ehstack.top->entry->outer_context = node->entry->outer_context; |
9762d48d | 1183 | |
e701eb4d JM |
1184 | /* Just rethrow. size_zero_node is just a NOP. */ |
1185 | expand_eh_region_end (size_zero_node); | |
9762d48d JM |
1186 | } |
1187 | ||
27a36778 MS |
1188 | /* If we are using the setjmp/longjmp EH codegen method, we emit a |
1189 | call to __sjthrow. | |
1190 | ||
1191 | Otherwise, we emit a call to __throw and note that we threw | |
1192 | something, so we know we need to generate the necessary code for | |
1193 | __throw. | |
12670d88 RK |
1194 | |
1195 | Before invoking throw, the __eh_pc variable must have been set up | |
1196 | to contain the PC being thrown from. This address is used by | |
27a36778 | 1197 | __throw to determine which exception region (if any) is |
abeeec2a | 1198 | responsible for handling the exception. */ |
4956d07c | 1199 | |
27a36778 | 1200 | void |
4956d07c MS |
1201 | emit_throw () |
1202 | { | |
27a36778 MS |
1203 | if (exceptions_via_longjmp) |
1204 | { | |
1205 | emit_library_call (sjthrow_libfunc, 0, VOIDmode, 0); | |
1206 | } | |
1207 | else | |
1208 | { | |
4956d07c | 1209 | #ifdef JUMP_TO_THROW |
27a36778 | 1210 | emit_indirect_jump (throw_libfunc); |
4956d07c | 1211 | #else |
27a36778 | 1212 | emit_library_call (throw_libfunc, 0, VOIDmode, 0); |
4956d07c | 1213 | #endif |
27a36778 MS |
1214 | throw_used = 1; |
1215 | } | |
4956d07c MS |
1216 | emit_barrier (); |
1217 | } | |
1218 | ||
e701eb4d JM |
1219 | /* Throw the current exception. If appropriate, this is done by jumping |
1220 | to the next handler. */ | |
4956d07c MS |
1221 | |
1222 | void | |
e701eb4d | 1223 | expand_internal_throw () |
4956d07c | 1224 | { |
e701eb4d | 1225 | emit_throw (); |
4956d07c MS |
1226 | } |
1227 | ||
1228 | /* Called from expand_exception_blocks and expand_end_catch_block to | |
27a36778 | 1229 | emit any pending handlers/cleanups queued from expand_eh_region_end. */ |
4956d07c MS |
1230 | |
1231 | void | |
1232 | expand_leftover_cleanups () | |
1233 | { | |
1234 | struct eh_entry *entry; | |
1235 | ||
1236 | while ((entry = dequeue_eh_entry (&ehqueue)) != 0) | |
1237 | { | |
1238 | rtx prev; | |
1239 | ||
12670d88 RK |
1240 | /* A leftover try block. Shouldn't be one here. */ |
1241 | if (entry->finalization == integer_zero_node) | |
1242 | abort (); | |
1243 | ||
abeeec2a | 1244 | /* Output the label for the start of the exception handler. */ |
4956d07c MS |
1245 | emit_label (entry->exception_handler_label); |
1246 | ||
f51430ed MS |
1247 | #ifdef HAVE_exception_receiver |
1248 | if (! exceptions_via_longjmp) | |
1249 | if (HAVE_exception_receiver) | |
1250 | emit_insn (gen_exception_receiver ()); | |
1251 | #endif | |
1252 | ||
05f5b2cd MS |
1253 | #ifdef HAVE_nonlocal_goto_receiver |
1254 | if (! exceptions_via_longjmp) | |
1255 | if (HAVE_nonlocal_goto_receiver) | |
1256 | emit_insn (gen_nonlocal_goto_receiver ()); | |
1257 | #endif | |
1258 | ||
abeeec2a | 1259 | /* And now generate the insns for the handler. */ |
4956d07c MS |
1260 | expand_expr (entry->finalization, const0_rtx, VOIDmode, 0); |
1261 | ||
1262 | prev = get_last_insn (); | |
27a36778 | 1263 | if (prev == NULL || GET_CODE (prev) != BARRIER) |
e701eb4d JM |
1264 | /* Emit code to throw to the outer context if we fall off |
1265 | the end of the handler. */ | |
1266 | expand_rethrow (entry->outer_context); | |
4956d07c | 1267 | |
c7ae64f2 | 1268 | do_pending_stack_adjust (); |
4956d07c MS |
1269 | free (entry); |
1270 | } | |
1271 | } | |
1272 | ||
abeeec2a | 1273 | /* Called at the start of a block of try statements. */ |
12670d88 RK |
1274 | void |
1275 | expand_start_try_stmts () | |
1276 | { | |
1277 | if (! doing_eh (1)) | |
1278 | return; | |
1279 | ||
1280 | expand_eh_region_start (); | |
1281 | } | |
1282 | ||
1283 | /* Generate RTL for the start of a group of catch clauses. | |
1284 | ||
1285 | It is responsible for starting a new instruction sequence for the | |
1286 | instructions in the catch block, and expanding the handlers for the | |
1287 | internally-generated exception regions nested within the try block | |
abeeec2a | 1288 | corresponding to this catch block. */ |
4956d07c MS |
1289 | |
1290 | void | |
1291 | expand_start_all_catch () | |
1292 | { | |
1293 | struct eh_entry *entry; | |
1294 | tree label; | |
e701eb4d | 1295 | rtx outer_context; |
4956d07c MS |
1296 | |
1297 | if (! doing_eh (1)) | |
1298 | return; | |
1299 | ||
e701eb4d | 1300 | outer_context = ehstack.top->entry->outer_context; |
1418bb67 | 1301 | |
abeeec2a | 1302 | /* End the try block. */ |
12670d88 RK |
1303 | expand_eh_region_end (integer_zero_node); |
1304 | ||
4956d07c MS |
1305 | emit_line_note (input_filename, lineno); |
1306 | label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE); | |
1307 | ||
12670d88 | 1308 | /* The label for the exception handling block that we will save. |
956d6950 | 1309 | This is Lresume in the documentation. */ |
4956d07c MS |
1310 | expand_label (label); |
1311 | ||
12670d88 | 1312 | /* Push the label that points to where normal flow is resumed onto |
abeeec2a | 1313 | the top of the label stack. */ |
4956d07c MS |
1314 | push_label_entry (&caught_return_label_stack, NULL_RTX, label); |
1315 | ||
1316 | /* Start a new sequence for all the catch blocks. We will add this | |
12670d88 | 1317 | to the global sequence catch_clauses when we have completed all |
4956d07c MS |
1318 | the handlers in this handler-seq. */ |
1319 | start_sequence (); | |
1320 | ||
1321 | while (1) | |
1322 | { | |
1323 | rtx prev; | |
1324 | ||
1325 | entry = dequeue_eh_entry (&ehqueue); | |
12670d88 RK |
1326 | /* Emit the label for the exception handler for this region, and |
1327 | expand the code for the handler. | |
1328 | ||
1329 | Note that a catch region is handled as a side-effect here; | |
1330 | for a try block, entry->finalization will contain | |
1331 | integer_zero_node, so no code will be generated in the | |
1332 | expand_expr call below. But, the label for the handler will | |
1333 | still be emitted, so any code emitted after this point will | |
abeeec2a | 1334 | end up being the handler. */ |
4956d07c | 1335 | emit_label (entry->exception_handler_label); |
4956d07c | 1336 | |
f51430ed MS |
1337 | #ifdef HAVE_exception_receiver |
1338 | if (! exceptions_via_longjmp) | |
1339 | if (HAVE_exception_receiver) | |
1340 | emit_insn (gen_exception_receiver ()); | |
1341 | #endif | |
1342 | ||
05f5b2cd MS |
1343 | #ifdef HAVE_nonlocal_goto_receiver |
1344 | if (! exceptions_via_longjmp) | |
1345 | if (HAVE_nonlocal_goto_receiver) | |
1346 | emit_insn (gen_nonlocal_goto_receiver ()); | |
1347 | #endif | |
1348 | ||
12670d88 | 1349 | /* When we get down to the matching entry for this try block, stop. */ |
4956d07c | 1350 | if (entry->finalization == integer_zero_node) |
12670d88 | 1351 | { |
abeeec2a | 1352 | /* Don't forget to free this entry. */ |
12670d88 RK |
1353 | free (entry); |
1354 | break; | |
1355 | } | |
4956d07c | 1356 | |
27a36778 MS |
1357 | /* And now generate the insns for the handler. */ |
1358 | expand_expr (entry->finalization, const0_rtx, VOIDmode, 0); | |
1359 | ||
4956d07c | 1360 | prev = get_last_insn (); |
12670d88 | 1361 | if (prev == NULL || GET_CODE (prev) != BARRIER) |
e701eb4d JM |
1362 | /* Code to throw out to outer context when we fall off end |
1363 | of the handler. We can't do this here for catch blocks, | |
1364 | so it's done in expand_end_all_catch instead. */ | |
1365 | expand_rethrow (entry->outer_context); | |
12670d88 | 1366 | |
f45ebe47 | 1367 | do_pending_stack_adjust (); |
4956d07c MS |
1368 | free (entry); |
1369 | } | |
e701eb4d JM |
1370 | |
1371 | /* If we are not doing setjmp/longjmp EH, because we are reordered | |
1372 | out of line, we arrange to rethrow in the outer context. We need to | |
1373 | do this because we are not physically within the region, if any, that | |
1374 | logically contains this catch block. */ | |
1375 | if (! exceptions_via_longjmp) | |
1376 | { | |
1377 | expand_eh_region_start (); | |
1378 | ehstack.top->entry->outer_context = outer_context; | |
1379 | } | |
4956d07c MS |
1380 | } |
1381 | ||
12670d88 RK |
1382 | /* Finish up the catch block. At this point all the insns for the |
1383 | catch clauses have already been generated, so we only have to add | |
1384 | them to the catch_clauses list. We also want to make sure that if | |
1385 | we fall off the end of the catch clauses that we rethrow to the | |
abeeec2a | 1386 | outer EH region. */ |
4956d07c MS |
1387 | |
1388 | void | |
1389 | expand_end_all_catch () | |
1390 | { | |
5dfa7520 | 1391 | rtx new_catch_clause, outer_context = NULL_RTX; |
4956d07c MS |
1392 | |
1393 | if (! doing_eh (1)) | |
1394 | return; | |
1395 | ||
e701eb4d | 1396 | if (! exceptions_via_longjmp) |
5dfa7520 JM |
1397 | { |
1398 | outer_context = ehstack.top->entry->outer_context; | |
1399 | ||
1400 | /* Finish the rethrow region. size_zero_node is just a NOP. */ | |
1401 | expand_eh_region_end (size_zero_node); | |
1402 | } | |
1403 | ||
e701eb4d JM |
1404 | /* Code to throw out to outer context, if we fall off end of catch |
1405 | handlers. This is rethrow (Lresume, same id, same obj) in the | |
1406 | documentation. We use Lresume because we know that it will throw | |
1407 | to the correct context. | |
12670d88 | 1408 | |
e701eb4d JM |
1409 | In other words, if the catch handler doesn't exit or return, we |
1410 | do a "throw" (using the address of Lresume as the point being | |
1411 | thrown from) so that the outer EH region can then try to process | |
1412 | the exception. */ | |
1413 | expand_rethrow (outer_context); | |
4956d07c MS |
1414 | |
1415 | /* Now we have the complete catch sequence. */ | |
1416 | new_catch_clause = get_insns (); | |
1417 | end_sequence (); | |
1418 | ||
1419 | /* This level of catch blocks is done, so set up the successful | |
1420 | catch jump label for the next layer of catch blocks. */ | |
1421 | pop_label_entry (&caught_return_label_stack); | |
956d6950 | 1422 | pop_label_entry (&outer_context_label_stack); |
4956d07c MS |
1423 | |
1424 | /* Add the new sequence of catches to the main one for this function. */ | |
1425 | push_to_sequence (catch_clauses); | |
1426 | emit_insns (new_catch_clause); | |
1427 | catch_clauses = get_insns (); | |
1428 | end_sequence (); | |
1429 | ||
1430 | /* Here we fall through into the continuation code. */ | |
1431 | } | |
1432 | ||
e701eb4d JM |
1433 | /* Rethrow from the outer context LABEL. */ |
1434 | ||
1435 | static void | |
1436 | expand_rethrow (label) | |
1437 | rtx label; | |
1438 | { | |
1439 | if (exceptions_via_longjmp) | |
1440 | emit_throw (); | |
1441 | else | |
1442 | emit_jump (label); | |
1443 | } | |
1444 | ||
12670d88 | 1445 | /* End all the pending exception regions on protect_list. The handlers |
27a36778 | 1446 | will be emitted when expand_leftover_cleanups is invoked. */ |
4956d07c MS |
1447 | |
1448 | void | |
1449 | end_protect_partials () | |
1450 | { | |
1451 | while (protect_list) | |
1452 | { | |
1453 | expand_eh_region_end (TREE_VALUE (protect_list)); | |
1454 | protect_list = TREE_CHAIN (protect_list); | |
1455 | } | |
1456 | } | |
27a36778 MS |
1457 | |
1458 | /* Arrange for __terminate to be called if there is an unhandled throw | |
1459 | from within E. */ | |
1460 | ||
1461 | tree | |
1462 | protect_with_terminate (e) | |
1463 | tree e; | |
1464 | { | |
1465 | /* We only need to do this when using setjmp/longjmp EH and the | |
1466 | language requires it, as otherwise we protect all of the handlers | |
1467 | at once, if we need to. */ | |
1468 | if (exceptions_via_longjmp && protect_cleanup_actions_with_terminate) | |
1469 | { | |
1470 | tree handler, result; | |
1471 | ||
1472 | /* All cleanups must be on the function_obstack. */ | |
1473 | push_obstacks_nochange (); | |
1474 | resume_temporary_allocation (); | |
1475 | ||
1476 | handler = make_node (RTL_EXPR); | |
1477 | TREE_TYPE (handler) = void_type_node; | |
1478 | RTL_EXPR_RTL (handler) = const0_rtx; | |
1479 | TREE_SIDE_EFFECTS (handler) = 1; | |
1480 | start_sequence_for_rtl_expr (handler); | |
1481 | ||
1482 | emit_library_call (terminate_libfunc, 0, VOIDmode, 0); | |
1483 | emit_barrier (); | |
1484 | ||
1485 | RTL_EXPR_SEQUENCE (handler) = get_insns (); | |
1486 | end_sequence (); | |
1487 | ||
1488 | result = build (TRY_CATCH_EXPR, TREE_TYPE (e), e, handler); | |
1489 | TREE_SIDE_EFFECTS (result) = TREE_SIDE_EFFECTS (e); | |
1490 | TREE_THIS_VOLATILE (result) = TREE_THIS_VOLATILE (e); | |
1491 | TREE_READONLY (result) = TREE_READONLY (e); | |
1492 | ||
1493 | pop_obstacks (); | |
1494 | ||
1495 | e = result; | |
1496 | } | |
1497 | ||
1498 | return e; | |
1499 | } | |
4956d07c MS |
1500 | \f |
1501 | /* The exception table that we build that is used for looking up and | |
12670d88 RK |
1502 | dispatching exceptions, the current number of entries, and its |
1503 | maximum size before we have to extend it. | |
1504 | ||
1505 | The number in eh_table is the code label number of the exception | |
27a36778 MS |
1506 | handler for the region. This is added by add_eh_table_entry and |
1507 | used by output_exception_table_entry. */ | |
12670d88 | 1508 | |
4956d07c MS |
1509 | static int *eh_table; |
1510 | static int eh_table_size; | |
1511 | static int eh_table_max_size; | |
1512 | ||
1513 | /* Note the need for an exception table entry for region N. If we | |
12670d88 RK |
1514 | don't need to output an explicit exception table, avoid all of the |
1515 | extra work. | |
1516 | ||
1517 | Called from final_scan_insn when a NOTE_INSN_EH_REGION_BEG is seen. | |
1518 | N is the NOTE_BLOCK_NUMBER of the note, which comes from the code | |
abeeec2a | 1519 | label number of the exception handler for the region. */ |
4956d07c MS |
1520 | |
1521 | void | |
1522 | add_eh_table_entry (n) | |
1523 | int n; | |
1524 | { | |
1525 | #ifndef OMIT_EH_TABLE | |
1526 | if (eh_table_size >= eh_table_max_size) | |
1527 | { | |
1528 | if (eh_table) | |
1529 | { | |
1530 | eh_table_max_size += eh_table_max_size>>1; | |
1531 | ||
1532 | if (eh_table_max_size < 0) | |
1533 | abort (); | |
1534 | ||
ca55abae JM |
1535 | eh_table = (int *) xrealloc (eh_table, |
1536 | eh_table_max_size * sizeof (int)); | |
4956d07c MS |
1537 | } |
1538 | else | |
1539 | { | |
1540 | eh_table_max_size = 252; | |
1541 | eh_table = (int *) xmalloc (eh_table_max_size * sizeof (int)); | |
1542 | } | |
1543 | } | |
1544 | eh_table[eh_table_size++] = n; | |
1545 | #endif | |
1546 | } | |
1547 | ||
12670d88 RK |
1548 | /* Return a non-zero value if we need to output an exception table. |
1549 | ||
1550 | On some platforms, we don't have to output a table explicitly. | |
1551 | This routine doesn't mean we don't have one. */ | |
4956d07c MS |
1552 | |
1553 | int | |
1554 | exception_table_p () | |
1555 | { | |
1556 | if (eh_table) | |
1557 | return 1; | |
1558 | ||
1559 | return 0; | |
1560 | } | |
1561 | ||
ca55abae JM |
1562 | /* 1 if we need a static constructor to register EH table info. */ |
1563 | ||
1564 | int | |
1565 | register_exception_table_p () | |
1566 | { | |
1567 | #if defined (DWARF2_UNWIND_INFO) | |
1568 | return 0; | |
1569 | #endif | |
1570 | ||
1571 | return exception_table_p (); | |
1572 | } | |
1573 | ||
12670d88 RK |
1574 | /* Output the entry of the exception table corresponding to to the |
1575 | exception region numbered N to file FILE. | |
1576 | ||
1577 | N is the code label number corresponding to the handler of the | |
abeeec2a | 1578 | region. */ |
4956d07c MS |
1579 | |
1580 | static void | |
1581 | output_exception_table_entry (file, n) | |
1582 | FILE *file; | |
1583 | int n; | |
1584 | { | |
1585 | char buf[256]; | |
1586 | rtx sym; | |
1587 | ||
1588 | ASM_GENERATE_INTERNAL_LABEL (buf, "LEHB", n); | |
1589 | sym = gen_rtx (SYMBOL_REF, Pmode, buf); | |
1590 | assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1); | |
1591 | ||
1592 | ASM_GENERATE_INTERNAL_LABEL (buf, "LEHE", n); | |
1593 | sym = gen_rtx (SYMBOL_REF, Pmode, buf); | |
1594 | assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1); | |
1595 | ||
1596 | ASM_GENERATE_INTERNAL_LABEL (buf, "L", n); | |
1597 | sym = gen_rtx (SYMBOL_REF, Pmode, buf); | |
1598 | assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1); | |
1599 | ||
1600 | putc ('\n', file); /* blank line */ | |
1601 | } | |
1602 | ||
abeeec2a | 1603 | /* Output the exception table if we have and need one. */ |
4956d07c MS |
1604 | |
1605 | void | |
1606 | output_exception_table () | |
1607 | { | |
1608 | int i; | |
1609 | extern FILE *asm_out_file; | |
1610 | ||
ca55abae | 1611 | if (! doing_eh (0) || ! eh_table) |
4956d07c MS |
1612 | return; |
1613 | ||
1614 | exception_section (); | |
1615 | ||
1616 | /* Beginning marker for table. */ | |
1617 | assemble_align (GET_MODE_ALIGNMENT (ptr_mode)); | |
1618 | assemble_label ("__EXCEPTION_TABLE__"); | |
1619 | ||
4956d07c MS |
1620 | for (i = 0; i < eh_table_size; ++i) |
1621 | output_exception_table_entry (asm_out_file, eh_table[i]); | |
1622 | ||
1623 | free (eh_table); | |
1624 | ||
1625 | /* Ending marker for table. */ | |
4956d07c MS |
1626 | assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1); |
1627 | assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1); | |
1628 | assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1); | |
1629 | putc ('\n', asm_out_file); /* blank line */ | |
1630 | } | |
1631 | ||
1632 | /* Generate code to initialize the exception table at program startup | |
1633 | time. */ | |
1634 | ||
1635 | void | |
1636 | register_exception_table () | |
1637 | { | |
1638 | emit_library_call (gen_rtx (SYMBOL_REF, Pmode, "__register_exceptions"), 0, | |
1639 | VOIDmode, 1, | |
1640 | gen_rtx (SYMBOL_REF, Pmode, "__EXCEPTION_TABLE__"), | |
1641 | Pmode); | |
1642 | } | |
1643 | \f | |
154bba13 TT |
1644 | /* Emit code to get EH context. |
1645 | ||
1646 | We have to scan thru the code to find possible EH context registers. | |
1647 | Inlined functions may use it too, and thus we'll have to be able | |
1648 | to change them too. | |
1649 | ||
1650 | This is done only if using exceptions_via_longjmp. */ | |
1651 | ||
1652 | void | |
1653 | emit_eh_context () | |
1654 | { | |
1655 | rtx insn; | |
1656 | rtx ehc = 0; | |
1657 | ||
1658 | if (! doing_eh (0)) | |
1659 | return; | |
1660 | ||
1661 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) | |
1662 | if (GET_CODE (insn) == INSN | |
1663 | && GET_CODE (PATTERN (insn)) == USE) | |
1664 | { | |
1665 | rtx reg = find_reg_note (insn, REG_EH_CONTEXT, 0); | |
1666 | if (reg) | |
1667 | { | |
1668 | rtx insns; | |
1669 | ||
100d81d4 JM |
1670 | start_sequence (); |
1671 | ||
1672 | /* If this is the first use insn, emit the call here. */ | |
154bba13 | 1673 | if (ehc == 0) |
01eb7f9a | 1674 | ehc = call_get_eh_context (); |
154bba13 | 1675 | |
154bba13 TT |
1676 | emit_move_insn (XEXP (reg, 0), ehc); |
1677 | insns = get_insns (); | |
1678 | end_sequence (); | |
1679 | ||
1680 | emit_insns_before (insns, insn); | |
1681 | } | |
1682 | } | |
1683 | } | |
1684 | ||
12670d88 RK |
1685 | /* Scan the current insns and build a list of handler labels. The |
1686 | resulting list is placed in the global variable exception_handler_labels. | |
1687 | ||
1688 | It is called after the last exception handling region is added to | |
1689 | the current function (when the rtl is almost all built for the | |
1690 | current function) and before the jump optimization pass. */ | |
4956d07c MS |
1691 | |
1692 | void | |
1693 | find_exception_handler_labels () | |
1694 | { | |
1695 | rtx insn; | |
1696 | int max_labelno = max_label_num (); | |
1697 | int min_labelno = get_first_label_num (); | |
1698 | rtx *labels; | |
1699 | ||
1700 | exception_handler_labels = NULL_RTX; | |
1701 | ||
1702 | /* If we aren't doing exception handling, there isn't much to check. */ | |
1703 | if (! doing_eh (0)) | |
1704 | return; | |
1705 | ||
12670d88 | 1706 | /* Generate a handy reference to each label. */ |
4956d07c | 1707 | |
1d77fa53 BK |
1708 | /* We call xmalloc here instead of alloca; we did the latter in the past, |
1709 | but found that it can sometimes end up being asked to allocate space | |
1710 | for more than 1 million labels. */ | |
1711 | labels = (rtx *) xmalloc ((max_labelno - min_labelno) * sizeof (rtx)); | |
abeeec2a | 1712 | bzero ((char *) labels, (max_labelno - min_labelno) * sizeof (rtx)); |
12670d88 | 1713 | |
abeeec2a | 1714 | /* Arrange for labels to be indexed directly by CODE_LABEL_NUMBER. */ |
4956d07c MS |
1715 | labels -= min_labelno; |
1716 | ||
1717 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) | |
1718 | { | |
1719 | if (GET_CODE (insn) == CODE_LABEL) | |
1720 | if (CODE_LABEL_NUMBER (insn) >= min_labelno | |
1721 | && CODE_LABEL_NUMBER (insn) < max_labelno) | |
1722 | labels[CODE_LABEL_NUMBER (insn)] = insn; | |
1723 | } | |
1724 | ||
12670d88 RK |
1725 | /* For each start of a region, add its label to the list. */ |
1726 | ||
4956d07c MS |
1727 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) |
1728 | { | |
1729 | if (GET_CODE (insn) == NOTE | |
1730 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG) | |
1731 | { | |
1732 | rtx label = NULL_RTX; | |
1733 | ||
1734 | if (NOTE_BLOCK_NUMBER (insn) >= min_labelno | |
1735 | && NOTE_BLOCK_NUMBER (insn) < max_labelno) | |
1736 | { | |
1737 | label = labels[NOTE_BLOCK_NUMBER (insn)]; | |
1738 | ||
1739 | if (label) | |
1740 | exception_handler_labels | |
1741 | = gen_rtx (EXPR_LIST, VOIDmode, | |
1742 | label, exception_handler_labels); | |
1743 | else | |
1744 | warning ("didn't find handler for EH region %d", | |
1745 | NOTE_BLOCK_NUMBER (insn)); | |
1746 | } | |
1747 | else | |
1748 | warning ("mismatched EH region %d", NOTE_BLOCK_NUMBER (insn)); | |
1749 | } | |
1750 | } | |
988cea7d | 1751 | |
3f34faec | 1752 | free (labels + min_labelno); |
4956d07c MS |
1753 | } |
1754 | ||
12670d88 RK |
1755 | /* Perform sanity checking on the exception_handler_labels list. |
1756 | ||
1757 | Can be called after find_exception_handler_labels is called to | |
1758 | build the list of exception handlers for the current function and | |
1759 | before we finish processing the current function. */ | |
4956d07c MS |
1760 | |
1761 | void | |
1762 | check_exception_handler_labels () | |
1763 | { | |
1764 | rtx insn, handler; | |
1765 | ||
1766 | /* If we aren't doing exception handling, there isn't much to check. */ | |
1767 | if (! doing_eh (0)) | |
1768 | return; | |
1769 | ||
12670d88 RK |
1770 | /* Ensure that the CODE_LABEL_NUMBER for the CODE_LABEL entry point |
1771 | in each handler corresponds to the CODE_LABEL_NUMBER of the | |
abeeec2a | 1772 | handler. */ |
12670d88 | 1773 | |
4956d07c MS |
1774 | for (handler = exception_handler_labels; |
1775 | handler; | |
1776 | handler = XEXP (handler, 1)) | |
1777 | { | |
1778 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) | |
1779 | { | |
1780 | if (GET_CODE (insn) == CODE_LABEL) | |
1781 | { | |
1782 | if (CODE_LABEL_NUMBER (insn) | |
1783 | == CODE_LABEL_NUMBER (XEXP (handler, 0))) | |
1784 | { | |
1785 | if (insn != XEXP (handler, 0)) | |
1786 | warning ("mismatched handler %d", | |
1787 | CODE_LABEL_NUMBER (insn)); | |
1788 | break; | |
1789 | } | |
1790 | } | |
1791 | } | |
1792 | if (insn == NULL_RTX) | |
1793 | warning ("handler not found %d", | |
1794 | CODE_LABEL_NUMBER (XEXP (handler, 0))); | |
1795 | } | |
1796 | ||
12670d88 RK |
1797 | /* Now go through and make sure that for each region there is a |
1798 | corresponding label. */ | |
4956d07c MS |
1799 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) |
1800 | { | |
1801 | if (GET_CODE (insn) == NOTE | |
27a36778 MS |
1802 | && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG |
1803 | || NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)) | |
4956d07c MS |
1804 | { |
1805 | for (handler = exception_handler_labels; | |
1806 | handler; | |
1807 | handler = XEXP (handler, 1)) | |
1808 | { | |
1809 | if (CODE_LABEL_NUMBER (XEXP (handler, 0)) | |
1810 | == NOTE_BLOCK_NUMBER (insn)) | |
1811 | break; | |
1812 | } | |
1813 | if (handler == NULL_RTX) | |
1814 | warning ("region exists, no handler %d", | |
1815 | NOTE_BLOCK_NUMBER (insn)); | |
1816 | } | |
1817 | } | |
1818 | } | |
1819 | \f | |
1820 | /* This group of functions initializes the exception handling data | |
1821 | structures at the start of the compilation, initializes the data | |
12670d88 | 1822 | structures at the start of a function, and saves and restores the |
4956d07c MS |
1823 | exception handling data structures for the start/end of a nested |
1824 | function. */ | |
1825 | ||
1826 | /* Toplevel initialization for EH things. */ | |
1827 | ||
1828 | void | |
1829 | init_eh () | |
1830 | { | |
12670d88 | 1831 | /* Generate rtl to reference the variable in which the PC of the |
abeeec2a | 1832 | current context is saved. */ |
843e8335 | 1833 | tree type = build_pointer_type (make_node (VOID_TYPE)); |
4956d07c MS |
1834 | } |
1835 | ||
abeeec2a | 1836 | /* Initialize the per-function EH information. */ |
4956d07c MS |
1837 | |
1838 | void | |
1839 | init_eh_for_function () | |
1840 | { | |
1841 | ehstack.top = 0; | |
1842 | ehqueue.head = ehqueue.tail = 0; | |
1843 | catch_clauses = NULL_RTX; | |
1844 | false_label_stack = 0; | |
1845 | caught_return_label_stack = 0; | |
1846 | protect_list = NULL_TREE; | |
154bba13 | 1847 | current_function_ehc = NULL_RTX; |
4956d07c MS |
1848 | } |
1849 | ||
12670d88 RK |
1850 | /* Save some of the per-function EH info into the save area denoted by |
1851 | P. | |
1852 | ||
27a36778 | 1853 | This is currently called from save_stmt_status. */ |
4956d07c MS |
1854 | |
1855 | void | |
1856 | save_eh_status (p) | |
1857 | struct function *p; | |
1858 | { | |
3a88cbd1 JL |
1859 | if (p == NULL) |
1860 | abort (); | |
12670d88 | 1861 | |
4956d07c MS |
1862 | p->ehstack = ehstack; |
1863 | p->ehqueue = ehqueue; | |
1864 | p->catch_clauses = catch_clauses; | |
1865 | p->false_label_stack = false_label_stack; | |
1866 | p->caught_return_label_stack = caught_return_label_stack; | |
1867 | p->protect_list = protect_list; | |
154bba13 | 1868 | p->ehc = current_function_ehc; |
4956d07c MS |
1869 | |
1870 | init_eh (); | |
1871 | } | |
1872 | ||
12670d88 RK |
1873 | /* Restore the per-function EH info saved into the area denoted by P. |
1874 | ||
abeeec2a | 1875 | This is currently called from restore_stmt_status. */ |
4956d07c MS |
1876 | |
1877 | void | |
1878 | restore_eh_status (p) | |
1879 | struct function *p; | |
1880 | { | |
3a88cbd1 JL |
1881 | if (p == NULL) |
1882 | abort (); | |
12670d88 | 1883 | |
4956d07c MS |
1884 | protect_list = p->protect_list; |
1885 | caught_return_label_stack = p->caught_return_label_stack; | |
1886 | false_label_stack = p->false_label_stack; | |
1887 | catch_clauses = p->catch_clauses; | |
1888 | ehqueue = p->ehqueue; | |
1889 | ehstack = p->ehstack; | |
154bba13 | 1890 | current_function_ehc = p->ehc; |
4956d07c MS |
1891 | } |
1892 | \f | |
1893 | /* This section is for the exception handling specific optimization | |
1894 | pass. First are the internal routines, and then the main | |
1895 | optimization pass. */ | |
1896 | ||
1897 | /* Determine if the given INSN can throw an exception. */ | |
1898 | ||
1899 | static int | |
1900 | can_throw (insn) | |
1901 | rtx insn; | |
1902 | { | |
abeeec2a | 1903 | /* Calls can always potentially throw exceptions. */ |
4956d07c MS |
1904 | if (GET_CODE (insn) == CALL_INSN) |
1905 | return 1; | |
1906 | ||
27a36778 MS |
1907 | if (asynchronous_exceptions) |
1908 | { | |
1909 | /* If we wanted asynchronous exceptions, then everything but NOTEs | |
1910 | and CODE_LABELs could throw. */ | |
1911 | if (GET_CODE (insn) != NOTE && GET_CODE (insn) != CODE_LABEL) | |
1912 | return 1; | |
1913 | } | |
4956d07c MS |
1914 | |
1915 | return 0; | |
1916 | } | |
1917 | ||
12670d88 RK |
1918 | /* Scan a exception region looking for the matching end and then |
1919 | remove it if possible. INSN is the start of the region, N is the | |
1920 | region number, and DELETE_OUTER is to note if anything in this | |
1921 | region can throw. | |
1922 | ||
1923 | Regions are removed if they cannot possibly catch an exception. | |
27a36778 | 1924 | This is determined by invoking can_throw on each insn within the |
12670d88 RK |
1925 | region; if can_throw returns true for any of the instructions, the |
1926 | region can catch an exception, since there is an insn within the | |
1927 | region that is capable of throwing an exception. | |
1928 | ||
1929 | Returns the NOTE_INSN_EH_REGION_END corresponding to this region, or | |
27a36778 | 1930 | calls abort if it can't find one. |
12670d88 RK |
1931 | |
1932 | Can abort if INSN is not a NOTE_INSN_EH_REGION_BEGIN, or if N doesn't | |
abeeec2a | 1933 | correspond to the region number, or if DELETE_OUTER is NULL. */ |
4956d07c MS |
1934 | |
1935 | static rtx | |
1936 | scan_region (insn, n, delete_outer) | |
1937 | rtx insn; | |
1938 | int n; | |
1939 | int *delete_outer; | |
1940 | { | |
1941 | rtx start = insn; | |
1942 | ||
1943 | /* Assume we can delete the region. */ | |
1944 | int delete = 1; | |
1945 | ||
3a88cbd1 JL |
1946 | if (insn == NULL_RTX |
1947 | || GET_CODE (insn) != NOTE | |
1948 | || NOTE_LINE_NUMBER (insn) != NOTE_INSN_EH_REGION_BEG | |
1949 | || NOTE_BLOCK_NUMBER (insn) != n | |
1950 | || delete_outer == NULL) | |
1951 | abort (); | |
12670d88 | 1952 | |
4956d07c MS |
1953 | insn = NEXT_INSN (insn); |
1954 | ||
1955 | /* Look for the matching end. */ | |
1956 | while (! (GET_CODE (insn) == NOTE | |
1957 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)) | |
1958 | { | |
1959 | /* If anything can throw, we can't remove the region. */ | |
1960 | if (delete && can_throw (insn)) | |
1961 | { | |
1962 | delete = 0; | |
1963 | } | |
1964 | ||
1965 | /* Watch out for and handle nested regions. */ | |
1966 | if (GET_CODE (insn) == NOTE | |
1967 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG) | |
1968 | { | |
1969 | insn = scan_region (insn, NOTE_BLOCK_NUMBER (insn), &delete); | |
1970 | } | |
1971 | ||
1972 | insn = NEXT_INSN (insn); | |
1973 | } | |
1974 | ||
1975 | /* The _BEG/_END NOTEs must match and nest. */ | |
1976 | if (NOTE_BLOCK_NUMBER (insn) != n) | |
1977 | abort (); | |
1978 | ||
12670d88 | 1979 | /* If anything in this exception region can throw, we can throw. */ |
4956d07c MS |
1980 | if (! delete) |
1981 | *delete_outer = 0; | |
1982 | else | |
1983 | { | |
1984 | /* Delete the start and end of the region. */ | |
1985 | delete_insn (start); | |
1986 | delete_insn (insn); | |
1987 | ||
1988 | /* Only do this part if we have built the exception handler | |
1989 | labels. */ | |
1990 | if (exception_handler_labels) | |
1991 | { | |
1992 | rtx x, *prev = &exception_handler_labels; | |
1993 | ||
1994 | /* Find it in the list of handlers. */ | |
1995 | for (x = exception_handler_labels; x; x = XEXP (x, 1)) | |
1996 | { | |
1997 | rtx label = XEXP (x, 0); | |
1998 | if (CODE_LABEL_NUMBER (label) == n) | |
1999 | { | |
2000 | /* If we are the last reference to the handler, | |
2001 | delete it. */ | |
2002 | if (--LABEL_NUSES (label) == 0) | |
2003 | delete_insn (label); | |
2004 | ||
2005 | if (optimize) | |
2006 | { | |
2007 | /* Remove it from the list of exception handler | |
2008 | labels, if we are optimizing. If we are not, then | |
2009 | leave it in the list, as we are not really going to | |
2010 | remove the region. */ | |
2011 | *prev = XEXP (x, 1); | |
2012 | XEXP (x, 1) = 0; | |
2013 | XEXP (x, 0) = 0; | |
2014 | } | |
2015 | ||
2016 | break; | |
2017 | } | |
2018 | prev = &XEXP (x, 1); | |
2019 | } | |
2020 | } | |
2021 | } | |
2022 | return insn; | |
2023 | } | |
2024 | ||
2025 | /* Perform various interesting optimizations for exception handling | |
2026 | code. | |
2027 | ||
12670d88 RK |
2028 | We look for empty exception regions and make them go (away). The |
2029 | jump optimization code will remove the handler if nothing else uses | |
abeeec2a | 2030 | it. */ |
4956d07c MS |
2031 | |
2032 | void | |
2033 | exception_optimize () | |
2034 | { | |
2035 | rtx insn, regions = NULL_RTX; | |
2036 | int n; | |
2037 | ||
12670d88 | 2038 | /* Remove empty regions. */ |
4956d07c MS |
2039 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) |
2040 | { | |
2041 | if (GET_CODE (insn) == NOTE | |
2042 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG) | |
2043 | { | |
27a36778 | 2044 | /* Since scan_region will return the NOTE_INSN_EH_REGION_END |
12670d88 RK |
2045 | insn, we will indirectly skip through all the insns |
2046 | inbetween. We are also guaranteed that the value of insn | |
27a36778 | 2047 | returned will be valid, as otherwise scan_region won't |
abeeec2a | 2048 | return. */ |
4956d07c MS |
2049 | insn = scan_region (insn, NOTE_BLOCK_NUMBER (insn), &n); |
2050 | } | |
2051 | } | |
2052 | } | |
ca55abae JM |
2053 | \f |
2054 | /* Various hooks for the DWARF 2 __throw routine. */ | |
2055 | ||
2056 | /* Do any necessary initialization to access arbitrary stack frames. | |
2057 | On the SPARC, this means flushing the register windows. */ | |
2058 | ||
2059 | void | |
2060 | expand_builtin_unwind_init () | |
2061 | { | |
2062 | /* Set this so all the registers get saved in our frame; we need to be | |
2063 | able to copy the saved values for any registers from frames we unwind. */ | |
2064 | current_function_has_nonlocal_label = 1; | |
2065 | ||
2066 | #ifdef SETUP_FRAME_ADDRESSES | |
2067 | SETUP_FRAME_ADDRESSES (); | |
2068 | #endif | |
2069 | } | |
2070 | ||
2071 | /* Given a value extracted from the return address register or stack slot, | |
2072 | return the actual address encoded in that value. */ | |
2073 | ||
2074 | rtx | |
2075 | expand_builtin_extract_return_addr (addr_tree) | |
2076 | tree addr_tree; | |
2077 | { | |
2078 | rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0); | |
2079 | return eh_outer_context (addr); | |
2080 | } | |
2081 | ||
2082 | /* Given an actual address in addr_tree, do any necessary encoding | |
2083 | and return the value to be stored in the return address register or | |
2084 | stack slot so the epilogue will return to that address. */ | |
2085 | ||
2086 | rtx | |
2087 | expand_builtin_frob_return_addr (addr_tree) | |
2088 | tree addr_tree; | |
2089 | { | |
2090 | rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0); | |
2091 | #ifdef RETURN_ADDR_OFFSET | |
2092 | addr = plus_constant (addr, -RETURN_ADDR_OFFSET); | |
2093 | #endif | |
2094 | return addr; | |
2095 | } | |
2096 | ||
2097 | /* Given an actual address in addr_tree, set the return address register up | |
2098 | so the epilogue will return to that address. If the return address is | |
2099 | not in a register, do nothing. */ | |
2100 | ||
2101 | void | |
2102 | expand_builtin_set_return_addr_reg (addr_tree) | |
2103 | tree addr_tree; | |
2104 | { | |
4f870c04 | 2105 | rtx tmp; |
ca55abae JM |
2106 | rtx ra = expand_builtin_return_addr (BUILT_IN_RETURN_ADDRESS, |
2107 | 0, hard_frame_pointer_rtx); | |
2108 | ||
2109 | if (GET_CODE (ra) != REG || REGNO (ra) >= FIRST_PSEUDO_REGISTER) | |
2110 | return; | |
2111 | ||
4f870c04 JM |
2112 | tmp = force_operand (expand_builtin_frob_return_addr (addr_tree), ra); |
2113 | if (tmp != ra) | |
2114 | emit_move_insn (ra, tmp); | |
ca55abae JM |
2115 | } |
2116 | ||
2117 | /* Choose two registers for communication between the main body of | |
2118 | __throw and the stub for adjusting the stack pointer. The first register | |
2119 | is used to pass the address of the exception handler; the second register | |
2120 | is used to pass the stack pointer offset. | |
2121 | ||
2122 | For register 1 we use the return value register for a void *. | |
2123 | For register 2 we use the static chain register if it exists and is | |
2124 | different from register 1, otherwise some arbitrary call-clobbered | |
2125 | register. */ | |
2126 | ||
2127 | static void | |
2128 | eh_regs (r1, r2, outgoing) | |
2129 | rtx *r1, *r2; | |
2130 | int outgoing; | |
2131 | { | |
2132 | rtx reg1, reg2; | |
2133 | ||
2134 | #ifdef FUNCTION_OUTGOING_VALUE | |
2135 | if (outgoing) | |
2136 | reg1 = FUNCTION_OUTGOING_VALUE (build_pointer_type (void_type_node), | |
2137 | current_function_decl); | |
2138 | else | |
2139 | #endif | |
2140 | reg1 = FUNCTION_VALUE (build_pointer_type (void_type_node), | |
2141 | current_function_decl); | |
2142 | ||
2143 | #ifdef STATIC_CHAIN_REGNUM | |
2144 | if (outgoing) | |
2145 | reg2 = static_chain_incoming_rtx; | |
2146 | else | |
2147 | reg2 = static_chain_rtx; | |
2148 | if (REGNO (reg2) == REGNO (reg1)) | |
2149 | #endif /* STATIC_CHAIN_REGNUM */ | |
2150 | reg2 = NULL_RTX; | |
2151 | ||
2152 | if (reg2 == NULL_RTX) | |
2153 | { | |
2154 | int i; | |
2155 | for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i) | |
2156 | if (call_used_regs[i] && ! fixed_regs[i] && i != REGNO (reg1)) | |
2157 | { | |
2158 | reg2 = gen_rtx (REG, Pmode, i); | |
2159 | break; | |
2160 | } | |
2161 | ||
2162 | if (reg2 == NULL_RTX) | |
2163 | abort (); | |
2164 | } | |
2165 | ||
2166 | *r1 = reg1; | |
2167 | *r2 = reg2; | |
2168 | } | |
2169 | ||
2170 | /* Emit inside of __throw a stub which adjusts the stack pointer and jumps | |
2171 | to the exception handler. __throw will set up the necessary values | |
2172 | and then return to the stub. */ | |
2173 | ||
2174 | rtx | |
2175 | expand_builtin_eh_stub () | |
2176 | { | |
2177 | rtx stub_start = gen_label_rtx (); | |
2178 | rtx after_stub = gen_label_rtx (); | |
2179 | rtx handler, offset, temp; | |
2180 | ||
2181 | emit_jump (after_stub); | |
2182 | emit_label (stub_start); | |
2183 | ||
2184 | eh_regs (&handler, &offset, 0); | |
2185 | ||
2186 | adjust_stack (offset); | |
2187 | emit_indirect_jump (handler); | |
2188 | ||
2189 | emit_label (after_stub); | |
2190 | return gen_rtx (LABEL_REF, Pmode, stub_start); | |
2191 | } | |
2192 | ||
2193 | /* Set up the registers for passing the handler address and stack offset | |
2194 | to the stub above. */ | |
2195 | ||
2196 | void | |
2197 | expand_builtin_set_eh_regs (handler, offset) | |
2198 | tree handler, offset; | |
2199 | { | |
2200 | rtx reg1, reg2; | |
2201 | ||
2202 | eh_regs (®1, ®2, 1); | |
2203 | ||
2204 | store_expr (offset, reg2, 0); | |
2205 | store_expr (handler, reg1, 0); | |
2206 | ||
2207 | /* These will be used by the stub. */ | |
2208 | emit_insn (gen_rtx (USE, VOIDmode, reg1)); | |
2209 | emit_insn (gen_rtx (USE, VOIDmode, reg2)); | |
2210 | } |