1 /*
2 * Copyright (c) 1998, 2009, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 // This file provides the basic support for exception handling in the VM.
26 // Note: We do not use C++ exceptions to avoid compiler dependencies and
27 // unpredictable performance.
28 //
29 // Scheme: Exceptions are stored with the thread. There is never more
30 // than one pending exception per thread. All functions that can throw
31 // an exception carry a THREAD argument (usually the last argument and
32 // declared with the TRAPS macro). Throwing an exception means setting
33 // a pending exception in the thread. Upon return from a function that
34 // can throw an exception, we must check if an exception is pending.
35 // The CHECK macros do this in a convenient way. Carrying around the
36 // thread provides also convenient access to it (e.g. for Handle
37 // creation, w/o the need for recomputation).
38
39
40
41 // Forward declarations to be independent of the include structure.
42 // This allows us to have exceptions.hpp included in top.hpp.
43
44 class Thread;
45 class Handle;
46 class symbolHandle;
47 class symbolOopDesc;
48 class JavaCallArguments;
49
50 // The ThreadShadow class is a helper class to access the _pending_exception
51 // field of the Thread class w/o having access to the Thread's interface (for
52 // include hierachy reasons).
53
54 class ThreadShadow: public CHeapObj {
55 protected:
56 oop _pending_exception; // Thread has gc actions.
57 const char* _exception_file; // file information for exception (debugging only)
58 int _exception_line; // line information for exception (debugging only)
59 friend void check_ThreadShadow(); // checks _pending_exception offset
60
61 // The following virtual exists only to force creation of a vtable.
62 // We need ThreadShadow to have a vtable, even in product builds,
63 // so that its layout will start at an offset of zero relative to Thread.
64 // Some C++ compilers are so "clever" that they put the ThreadShadow
65 // base class at offset 4 in Thread (after Thread's vtable), if they
66 // notice that Thread has a vtable but ThreadShadow does not.
67 virtual void unused_initial_virtual() { }
68
69 public:
70 oop pending_exception() const { return _pending_exception; }
71 bool has_pending_exception() const { return _pending_exception != NULL; }
72 const char* exception_file() const { return _exception_file; }
73 int exception_line() const { return _exception_line; }
74
75 // Code generation support
76 static ByteSize pending_exception_offset() { return byte_offset_of(ThreadShadow, _pending_exception); }
77
78 // use THROW whenever possible!
79 void set_pending_exception(oop exception, const char* file, int line);
80
81 // use CLEAR_PENDING_EXCEPTION whenever possible!
82 void clear_pending_exception();
83
84 ThreadShadow() : _pending_exception(NULL),
85 _exception_file(NULL), _exception_line(0) {}
86 };
87
88
89 // Exceptions is a helper class that encapsulates all operations
90 // that require access to the thread interface and which are
91 // relatively rare. The Exceptions operations should only be
92 // used directly if the macros below are insufficient.
93
94 class Exceptions {
95 static bool special_exception(Thread *thread, const char* file, int line, Handle exception);
96 static bool special_exception(Thread* thread, const char* file, int line, symbolHandle name, const char* message);
97 public:
98 // this enum is defined to indicate whether it is safe to
99 // ignore the encoding scheme of the original message string.
100 typedef enum {
101 safe_to_utf8 = 0,
102 unsafe_to_utf8 = 1
103 } ExceptionMsgToUtf8Mode;
104 // Throw exceptions: w/o message, w/ message & with formatted message.
105 static void _throw_oop(Thread* thread, const char* file, int line, oop exception);
106 static void _throw(Thread* thread, const char* file, int line, Handle exception, const char* msg = NULL);
107 static void _throw_msg(Thread* thread, const char* file, int line,
108 symbolHandle name, const char* message, Handle loader,
109 Handle protection_domain);
110 static void _throw_msg(Thread* thread, const char* file, int line,
111 symbolOop name, const char* message);
112 static void _throw_msg(Thread* thread, const char* file, int line,
113 symbolHandle name, const char* message);
114 static void _throw_args(Thread* thread, const char* file, int line,
115 symbolHandle name, symbolHandle signature,
116 JavaCallArguments* args);
117 static void _throw_msg_cause(Thread* thread, const char* file,
118 int line, symbolHandle h_name, const char* message,
119 Handle h_cause, Handle h_loader, Handle h_protection_domain);
120 static void _throw_msg_cause(Thread* thread, const char* file, int line,
121 symbolHandle name, const char* message, Handle cause);
122
123 // There is no THROW... macro for this method. Caller should remember
124 // to do a return after calling it.
125 static void fthrow(Thread* thread, const char* file, int line, symbolHandle name,
126 const char* format, ...);
127
128 // Create and initialize a new exception
129 static Handle new_exception(Thread* thread, symbolHandle name,
130 symbolHandle signature, JavaCallArguments* args,
131 Handle cause, Handle loader,
132 Handle protection_domain);
133
134 static Handle new_exception(Thread* thread, symbolHandle name,
135 const char* message, Handle cause, Handle loader,
136 Handle protection_domain,
137 ExceptionMsgToUtf8Mode to_utf8_safe = safe_to_utf8);
138
139 static Handle new_exception(Thread* thread, symbolOop name,
140 const char* message,
141 ExceptionMsgToUtf8Mode to_utf8_safe = safe_to_utf8);
142
143 static void throw_stack_overflow_exception(Thread* thread, const char* file, int line);
144
145 // for AbortVMOnException flag
146 NOT_PRODUCT(static void debug_check_abort(Handle exception, const char* message = NULL);)
147 NOT_PRODUCT(static void debug_check_abort(const char *value_string, const char* message = NULL);)
148 };
149
150
151 // The THREAD & TRAPS macros facilitate the declaration of functions that throw exceptions.
152 // Convention: Use the TRAPS macro as the last argument of such a function; e.g.:
153 //
154 // int this_function_may_trap(int x, float y, TRAPS)
155
156 #define THREAD __the_thread__
157 #define TRAPS Thread* THREAD
158
159
160 // The CHECK... macros should be used to pass along a THREAD reference and to check for pending
161 // exceptions. In special situations it is necessary to handle pending exceptions explicitly,
162 // in these cases the PENDING_EXCEPTION helper macros should be used.
163 //
164 // Macro naming conventions: Macros that end with _ require a result value to be returned. They
165 // are for functions with non-void result type. The result value is usually ignored because of
166 // the exception and is only needed for syntactic correctness. The _0 ending is a shortcut for
167 // _(0) since this is a frequent case. Example:
168 //
169 // int result = this_function_may_trap(x_arg, y_arg, CHECK_0);
170 //
171 // CAUTION: make sure that the function call using a CHECK macro is not the only statement of a
172 // conditional branch w/o enclosing {} braces, since the CHECK macros expand into several state-
173 // ments!
174
175 #define PENDING_EXCEPTION (((ThreadShadow*)THREAD)->pending_exception())
176 #define HAS_PENDING_EXCEPTION (((ThreadShadow*)THREAD)->has_pending_exception())
177 #define CLEAR_PENDING_EXCEPTION (((ThreadShadow*)THREAD)->clear_pending_exception())
178
179 #define CHECK THREAD); if (HAS_PENDING_EXCEPTION) return ; (0
180 #define CHECK_(result) THREAD); if (HAS_PENDING_EXCEPTION) return result; (0
181 #define CHECK_0 CHECK_(0)
182 #define CHECK_NH CHECK_(Handle())
183 #define CHECK_NULL CHECK_(NULL)
184 #define CHECK_false CHECK_(false)
185
186 // The THROW... macros should be used to throw an exception. They require a THREAD variable to be
187 // visible within the scope containing the THROW. Usually this is achieved by declaring the function
188 // with a TRAPS argument.
189
190 #define THREAD_AND_LOCATION THREAD, __FILE__, __LINE__
191
192 #define THROW_OOP(e) \
193 { Exceptions::_throw_oop(THREAD_AND_LOCATION, e); return; }
194
195 #define THROW_HANDLE(e) \
196 { Exceptions::_throw(THREAD_AND_LOCATION, e); return; }
197
198 #define THROW(name) \
199 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, NULL); return; }
200
201 #define THROW_MSG(name, message) \
202 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message); return; }
203
204 #define THROW_MSG_LOADER(name, message, loader, protection_domain) \
205 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message, loader, protection_domain); return; }
206
207 #define THROW_ARG(name, signature, args) \
208 { Exceptions::_throw_args(THREAD_AND_LOCATION, name, signature, args); return; }
209
210 #define THROW_OOP_(e, result) \
211 { Exceptions::_throw_oop(THREAD_AND_LOCATION, e); return result; }
212
213 #define THROW_HANDLE_(e, result) \
214 { Exceptions::_throw(THREAD_AND_LOCATION, e); return result; }
215
216 #define THROW_(name, result) \
217 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, NULL); return result; }
218
219 #define THROW_MSG_(name, message, result) \
220 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message); return result; }
221
222 #define THROW_MSG_LOADER_(name, message, loader, protection_domain, result) \
223 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message, loader, protection_domain); return result; }
224
225 #define THROW_ARG_(name, signature, args, result) \
226 { Exceptions::_throw_args(THREAD_AND_LOCATION, name, signature, args); return result; }
227
228 #define THROW_MSG_CAUSE_(name, message, cause, result) \
229 { Exceptions::_throw_msg_cause(THREAD_AND_LOCATION, name, message, cause); return result; }
230
231
232 #define THROW_OOP_0(e) THROW_OOP_(e, 0)
233 #define THROW_HANDLE_0(e) THROW_HANDLE_(e, 0)
234 #define THROW_0(name) THROW_(name, 0)
235 #define THROW_MSG_0(name, message) THROW_MSG_(name, message, 0)
236 #define THROW_WRAPPED_0(name, oop_to_wrap) THROW_WRAPPED_(name, oop_to_wrap, 0)
237 #define THROW_ARG_0(name, signature, arg) THROW_ARG_(name, signature, arg, 0)
238 #define THROW_MSG_CAUSE_0(name, message, cause) THROW_MSG_CAUSE_(name, message, cause, 0)
239
240 #define THROW_NULL(name) THROW_(name, NULL)
241 #define THROW_MSG_NULL(name, message) THROW_MSG_(name, message, NULL)
242
243 // The CATCH macro checks that no exception has been thrown by a function; it is used at
244 // call sites about which is statically known that the callee cannot throw an exception
245 // even though it is declared with TRAPS.
246
247 #define CATCH \
248 THREAD); if (HAS_PENDING_EXCEPTION) { \
249 oop ex = PENDING_EXCEPTION; \
250 CLEAR_PENDING_EXCEPTION; \
251 ex->print(); \
252 ShouldNotReachHere(); \
253 } (0
254
255
256 // ExceptionMark is a stack-allocated helper class for local exception handling.
257 // It is used with the EXCEPTION_MARK macro.
258
259 class ExceptionMark {
260 private:
261 Thread* _thread;
262
263 public:
264 ExceptionMark(Thread*& thread);
265 ~ExceptionMark();
266 };
267
268
269
270 // Use an EXCEPTION_MARK for 'local' exceptions. EXCEPTION_MARK makes sure that no
271 // pending exception exists upon entering its scope and tests that no pending exception
272 // exists when leaving the scope.
273
274 // See also preserveException.hpp for PRESERVE_EXCEPTION_MARK macro,
275 // which preserves pre-existing exceptions and does not allow new
276 // exceptions.
277
278 #define EXCEPTION_MARK Thread* THREAD; ExceptionMark __em(THREAD);