1 // Functions for Exception Support for Java.
3 /* Copyright (C) 1998, 1999, 2001 Free Software Foundation
5 This file is part of libgcj.
7 This software is copyrighted work licensed under the terms of the
8 Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
16 #include <java/lang/Class.h>
17 #include <java/lang/NullPointerException.h>
24 // More nastiness: the GC wants to define TRUE and FALSE. We don't
25 // need the Java definitions (themselves a hack), so we undefine them.
33 #include <include/gc_gcj.h>
37 struct alignment_test_struct
40 char end
[0] __attribute__((aligned
));
43 struct java_exception_header
45 /* Cache handler details between Phase 1 and Phase 2. */
46 _Unwind_Ptr landingPad
;
47 int handlerSwitchValue
;
49 /* The object being thrown. Compiled code expects this to be immediately
50 before the generic exception header. Which is complicated by the fact
51 that _Unwind_Exception is ((aligned)). */
53 char pad
[sizeof(jthrowable
) < sizeof(alignment_test_struct
)
54 ? sizeof(alignment_test_struct
) - sizeof(jthrowable
) : 0]
55 __attribute__((aligned
));
59 /* The generic exception header. */
60 _Unwind_Exception unwindHeader
;
63 // This is the exception class we report -- "GNUCJAVA".
64 const _Unwind_Exception_Class __gcj_exception_class
65 = ((((((((_Unwind_Exception_Class
) 'G'
66 << 8 | (_Unwind_Exception_Class
) 'N')
67 << 8 | (_Unwind_Exception_Class
) 'U')
68 << 8 | (_Unwind_Exception_Class
) 'C')
69 << 8 | (_Unwind_Exception_Class
) 'J')
70 << 8 | (_Unwind_Exception_Class
) 'A')
71 << 8 | (_Unwind_Exception_Class
) 'V')
72 << 8 | (_Unwind_Exception_Class
) 'A');
75 static inline java_exception_header
*
76 get_exception_header_from_ue (_Unwind_Exception
*exc
)
78 return reinterpret_cast<java_exception_header
*>(exc
+ 1) - 1;
81 /* Perform a throw, Java style. Throw will unwind through this call,
82 so there better not be any handlers or exception thrown here. */
85 _Jv_Throw (jthrowable value
)
87 /* FIXME: Use the proper API to the collector. */
88 java_exception_header
*xh
89 = static_cast<java_exception_header
*>(GC_malloc (sizeof (*xh
)));
92 value
= new java::lang::NullPointerException ();
95 xh
->unwindHeader
.exception_class
= __gcj_exception_class
;
96 xh
->unwindHeader
.exception_cleanup
= NULL
;
98 /* We're happy with setjmp/longjmp exceptions or region-based
99 exception handlers: entry points are provided here for both. */
100 _Unwind_Reason_Code code
;
101 #ifdef SJLJ_EXCEPTIONS
102 code
= _Unwind_SjLj_RaiseException (&xh
->unwindHeader
);
104 code
= _Unwind_RaiseException (&xh
->unwindHeader
);
107 /* If code == _URC_END_OF_STACK, then we reached top of stack without
108 finding a handler for the exception. Since each thread is run in
109 a try/catch, this oughtn't happen. If code is something else, we
110 encountered some sort of heinous lossage from which we could not
111 recover. As is the way of such things, almost certainly we will have
112 crashed before now, rather than actually being able to diagnose the
118 #include "unwind-pe.h"
120 struct lsda_header_info
124 const unsigned char *TType
;
125 const unsigned char *action_table
;
126 unsigned char ttype_encoding
;
127 unsigned char call_site_encoding
;
130 static const unsigned char *
131 parse_lsda_header (_Unwind_Context
*context
, const unsigned char *p
,
132 lsda_header_info
*info
)
135 unsigned char lpstart_encoding
;
137 info
->Start
= (context
? _Unwind_GetRegionStart (context
) : 0);
139 // Find @LPStart, the base to which landing pad offsets are relative.
140 lpstart_encoding
= *p
++;
141 if (lpstart_encoding
!= DW_EH_PE_omit
)
142 p
= read_encoded_value (context
, lpstart_encoding
, p
, &info
->LPStart
);
144 info
->LPStart
= info
->Start
;
146 // Find @TType, the base of the handler and exception spec type data.
147 info
->ttype_encoding
= *p
++;
148 if (info
->ttype_encoding
!= DW_EH_PE_omit
)
150 p
= read_uleb128 (p
, &tmp
);
151 info
->TType
= p
+ tmp
;
156 // The encoding and length of the call-site table; the action table
157 // immediately follows.
158 info
->call_site_encoding
= *p
++;
159 p
= read_uleb128 (p
, &tmp
);
160 info
->action_table
= p
+ tmp
;
166 get_ttype_entry (_Unwind_Context
*context
, lsda_header_info
*info
, long i
)
170 i
*= size_of_encoded_value (info
->ttype_encoding
);
171 read_encoded_value (context
, info
->ttype_encoding
, info
->TType
- i
, &ptr
);
173 return reinterpret_cast<jclass
>(ptr
);
177 // Using a different personality function name causes link failures
178 // when trying to mix code using different exception handling models.
179 #ifdef SJLJ_EXCEPTIONS
180 #define PERSONALITY_FUNCTION __gcj_personality_sj0
181 #define __builtin_eh_return_data_regno(x) x
183 #define PERSONALITY_FUNCTION __gcj_personality_v0
186 extern "C" _Unwind_Reason_Code
187 PERSONALITY_FUNCTION (int version
,
188 _Unwind_Action actions
,
189 _Unwind_Exception_Class exception_class
,
190 struct _Unwind_Exception
*ue_header
,
191 struct _Unwind_Context
*context
)
193 java_exception_header
*xh
= get_exception_header_from_ue (ue_header
);
195 lsda_header_info info
;
196 const unsigned char *language_specific_data
;
197 const unsigned char *action_record
;
198 const unsigned char *p
;
199 _Unwind_Ptr landing_pad
, ip
;
200 int handler_switch_value
;
205 // Interface version check.
207 return _URC_FATAL_PHASE1_ERROR
;
209 // Shortcut for phase 2 found handler for domestic exception.
210 if (actions
== (_UA_CLEANUP_PHASE
| _UA_HANDLER_FRAME
)
211 && exception_class
== __gcj_exception_class
)
213 handler_switch_value
= xh
->handlerSwitchValue
;
214 landing_pad
= xh
->landingPad
;
215 goto install_context
;
218 // FIXME: In Phase 1, record _Unwind_GetIP in xh->obj as a part of
219 // the stack trace for this exception. This will only collect Java
220 // frames, but perhaps that is acceptable.
221 // FIXME2: _Unwind_GetIP is nonsensical for SJLJ, being a call-site
222 // index instead of a PC value. We could perhaps arrange for
223 // _Unwind_GetRegionStart to return context->fc->jbuf[1], which
224 // is the address of the handler label for __builtin_longjmp, but
225 // there is no solution for DONT_USE_BUILTIN_SETJMP.
227 language_specific_data
= (const unsigned char *)
228 _Unwind_GetLanguageSpecificData (context
);
230 // If no LSDA, then there are no handlers or cleanups.
231 if (! language_specific_data
)
232 return _URC_CONTINUE_UNWIND
;
234 // Parse the LSDA header.
235 p
= parse_lsda_header (context
, language_specific_data
, &info
);
236 ip
= _Unwind_GetIP (context
) - 1;
239 handler_switch_value
= 0;
241 #ifdef SJLJ_EXCEPTIONS
242 // The given "IP" is an index into the call-site table, with two
243 // exceptions -- -1 means no-action, and 0 means terminate. But
244 // since we're using uleb128 values, we've not got random access
247 return _URC_CONTINUE_UNWIND
;
250 _Unwind_Ptr cs_lp
, cs_action
;
253 p
= read_uleb128 (p
, &cs_lp
);
254 p
= read_uleb128 (p
, &cs_action
);
258 // Can never have null landing pad for sjlj -- that would have
259 // been indicated by a -1 call site index.
260 landing_pad
= cs_lp
+ 1;
262 action_record
= info
.action_table
+ cs_action
- 1;
263 goto found_something
;
266 // Search the call-site table for the action associated with this IP.
267 while (p
< info
.action_table
)
269 _Unwind_Ptr cs_start
, cs_len
, cs_lp
, cs_action
;
271 // Note that all call-site encodings are "absolute" displacements.
272 p
= read_encoded_value (0, info
.call_site_encoding
, p
, &cs_start
);
273 p
= read_encoded_value (0, info
.call_site_encoding
, p
, &cs_len
);
274 p
= read_encoded_value (0, info
.call_site_encoding
, p
, &cs_lp
);
275 p
= read_uleb128 (p
, &cs_action
);
277 // The table is sorted, so if we've passed the ip, stop.
278 if (ip
< info
.Start
+ cs_start
)
279 p
= info
.action_table
;
280 else if (ip
< info
.Start
+ cs_start
+ cs_len
)
283 landing_pad
= info
.LPStart
+ cs_lp
;
285 action_record
= info
.action_table
+ cs_action
- 1;
286 goto found_something
;
289 #endif // SJLJ_EXCEPTIONS
291 // If ip is not present in the table, C++ would call terminate.
292 // ??? It is perhaps better to tweek the LSDA so that no-action
293 // is mapped to no-entry for Java.
294 return _URC_CONTINUE_UNWIND
;
300 if (landing_pad
== 0)
302 // If ip is present, and has a null landing pad, there are
303 // no cleanups or handlers to be run.
305 else if (action_record
== 0)
307 // If ip is present, has a non-null landing pad, and a null
308 // action table offset, then there are only cleanups present.
309 // Cleanups use a zero switch value, as set above.
314 // Otherwise we have a catch handler.
315 signed long ar_filter
, ar_disp
;
322 p
= read_sleb128 (p
, &tmp
); ar_filter
= tmp
;
323 read_sleb128 (p
, &tmp
); ar_disp
= tmp
;
327 // Zero filter values are cleanups.
331 // During forced unwinding, we only run cleanups. With a
332 // foreign exception class, we have no class info to match.
333 else if ((actions
& _UA_FORCE_UNWIND
)
334 || exception_class
!= __gcj_exception_class
)
337 else if (ar_filter
> 0)
339 // Positive filter values are handlers.
341 jclass catch_type
= get_ttype_entry (context
, &info
, ar_filter
);
343 // The catch_type is either a (java::lang::Class*) or
344 // is one more than a (Utf8Const*).
345 if ((size_t)catch_type
& 1)
346 catch_type
= _Jv_FindClass ((Utf8Const
*)catch_type
- 1, NULL
);
348 if (_Jv_IsInstanceOf (xh
->value
, catch_type
))
350 handler_switch_value
= ar_filter
;
357 // Negative filter values are exception specifications,
358 // which Java does not use.
359 // ??? Perhaps better to make them an index into a table
360 // of null-terminated strings instead of playing games
361 // with Utf8Const+1 as above.
367 action_record
= p
+ ar_disp
;
371 if (! saw_handler
&& ! saw_cleanup
)
372 return _URC_CONTINUE_UNWIND
;
374 if (actions
& _UA_SEARCH_PHASE
)
377 return _URC_CONTINUE_UNWIND
;
379 // For domestic exceptions, we cache data from phase 1 for phase 2.
380 if (exception_class
== __gcj_exception_class
)
382 xh
->handlerSwitchValue
= handler_switch_value
;
383 xh
->landingPad
= landing_pad
;
385 return _URC_HANDLER_FOUND
;
389 _Unwind_SetGR (context
, __builtin_eh_return_data_regno (0),
390 (_Unwind_Ptr
) &xh
->unwindHeader
);
391 _Unwind_SetGR (context
, __builtin_eh_return_data_regno (1),
392 handler_switch_value
);
393 _Unwind_SetIP (context
, landing_pad
);
394 return _URC_INSTALL_CONTEXT
;