1 /*
2 * Copyright (c) 1998, 2011, 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 #ifndef SHARE_VM_UTILITIES_EXCEPTIONS_HPP
26 #define SHARE_VM_UTILITIES_EXCEPTIONS_HPP
27
28 #include "memory/allocation.hpp"
29 #include "oops/oopsHierarchy.hpp"
30 #include "utilities/sizes.hpp"
31
32 // This file provides the basic support for exception handling in the VM.
33 // Note: We do not use C++ exceptions to avoid compiler dependencies and
34 // unpredictable performance.
35 //
36 // Scheme: Exceptions are stored with the thread. There is never more
37 // than one pending exception per thread. All functions that can throw
38 // an exception carry a THREAD argument (usually the last argument and
39 // declared with the TRAPS macro). Throwing an exception means setting
40 // a pending exception in the thread. Upon return from a function that
41 // can throw an exception, we must check if an exception is pending.
42 // The CHECK macros do this in a convenient way. Carrying around the
43 // thread provides also convenient access to it (e.g. for Handle
44 // creation, w/o the need for recomputation).
45
46
47
48 // Forward declarations to be independent of the include structure.
49 // This allows us to have exceptions.hpp included in top.hpp.
50
51 class Thread;
52 class Handle;
53 class Symbol;
54 class JavaCallArguments;
55
56 // The ThreadShadow class is a helper class to access the _pending_exception
57 // field of the Thread class w/o having access to the Thread's interface (for
58 // include hierachy reasons).
59
60 class ThreadShadow: public CHeapObj {
61 protected:
62 oop _pending_exception; // Thread has gc actions.
63 const char* _exception_file; // file information for exception (debugging only)
64 int _exception_line; // line information for exception (debugging only)
65 friend void check_ThreadShadow(); // checks _pending_exception offset
66
67 // The following virtual exists only to force creation of a vtable.
68 // We need ThreadShadow to have a vtable, even in product builds,
69 // so that its layout will start at an offset of zero relative to Thread.
70 // Some C++ compilers are so "clever" that they put the ThreadShadow
71 // base class at offset 4 in Thread (after Thread's vtable), if they
72 // notice that Thread has a vtable but ThreadShadow does not.
73 virtual void unused_initial_virtual() { }
74
75 public:
76 oop pending_exception() const { return _pending_exception; }
77 bool has_pending_exception() const { return _pending_exception != NULL; }
78 const char* exception_file() const { return _exception_file; }
79 int exception_line() const { return _exception_line; }
80
81 // Code generation support
82 static ByteSize pending_exception_offset() { return byte_offset_of(ThreadShadow, _pending_exception); }
83
84 // use THROW whenever possible!
85 void set_pending_exception(oop exception, const char* file, int line);
86
87 // use CLEAR_PENDING_EXCEPTION whenever possible!
88 void clear_pending_exception();
89
90 ThreadShadow() : _pending_exception(NULL),
91 _exception_file(NULL), _exception_line(0) {}
92 };
93
94
95 // Exceptions is a helper class that encapsulates all operations
96 // that require access to the thread interface and which are
97 // relatively rare. The Exceptions operations should only be
98 // used directly if the macros below are insufficient.
99
100 class Exceptions {
101 static bool special_exception(Thread *thread, const char* file, int line, Handle exception);
102 static bool special_exception(Thread* thread, const char* file, int line, Symbol* name, const char* message);
103 public:
104 // this enum is defined to indicate whether it is safe to
105 // ignore the encoding scheme of the original message string.
106 typedef enum {
107 safe_to_utf8 = 0,
108 unsafe_to_utf8 = 1
109 } ExceptionMsgToUtf8Mode;
110 // Throw exceptions: w/o message, w/ message & with formatted message.
111 static void _throw_oop(Thread* thread, const char* file, int line, oop exception);
112 static void _throw(Thread* thread, const char* file, int line, Handle exception, const char* msg = NULL);
113 static void _throw_msg(Thread* thread, const char* file, int line,
114 Symbol* name, const char* message, Handle loader,
115 Handle protection_domain);
116 static void _throw_msg(Thread* thread, const char* file, int line,
117 Symbol* name, const char* message);
118 static void _throw_args(Thread* thread, const char* file, int line,
119 Symbol* name, Symbol* signature,
120 JavaCallArguments* args);
121 static void _throw_msg_cause(Thread* thread, const char* file,
122 int line, Symbol* h_name, const char* message,
123 Handle h_cause, Handle h_loader, Handle h_protection_domain);
124 static void _throw_msg_cause(Thread* thread, const char* file, int line,
125 Symbol* name, const char* message, Handle cause);
126
127 // There is no THROW... macro for this method. Caller should remember
128 // to do a return after calling it.
129 static void fthrow(Thread* thread, const char* file, int line, Symbol* name,
130 const char* format, ...);
131
132 // Create and initialize a new exception
133 static Handle new_exception(Thread* thread, Symbol* name,
134 Symbol* signature, JavaCallArguments* args,
135 Handle cause, Handle loader,
136 Handle protection_domain);
137
138 static Handle new_exception(Thread* thread, Symbol* name,
139 const char* message, Handle cause, Handle loader,
140 Handle protection_domain,
141 ExceptionMsgToUtf8Mode to_utf8_safe = safe_to_utf8);
142
143 static Handle new_exception(Thread* thread, Symbol* name,
144 const char* message,
145 ExceptionMsgToUtf8Mode to_utf8_safe = safe_to_utf8);
146
147 static void throw_stack_overflow_exception(Thread* thread, const char* file, int line, methodHandle method);
148
149 // for AbortVMOnException flag
150 NOT_PRODUCT(static void debug_check_abort(Handle exception, const char* message = NULL);)
151 NOT_PRODUCT(static void debug_check_abort(const char *value_string, const char* message = NULL);)
152 };
153
154
155 // The THREAD & TRAPS macros facilitate the declaration of functions that throw exceptions.
156 // Convention: Use the TRAPS macro as the last argument of such a function; e.g.:
157 //
158 // int this_function_may_trap(int x, float y, TRAPS)
159
160 #define THREAD __the_thread__
161 #define TRAPS Thread* THREAD
162
163
164 // The CHECK... macros should be used to pass along a THREAD reference and to check for pending
165 // exceptions. In special situations it is necessary to handle pending exceptions explicitly,
166 // in these cases the PENDING_EXCEPTION helper macros should be used.
167 //
168 // Macro naming conventions: Macros that end with _ require a result value to be returned. They
169 // are for functions with non-void result type. The result value is usually ignored because of
170 // the exception and is only needed for syntactic correctness. The _0 ending is a shortcut for
171 // _(0) since this is a frequent case. Example:
172 //
173 // int result = this_function_may_trap(x_arg, y_arg, CHECK_0);
174 //
175 // CAUTION: make sure that the function call using a CHECK macro is not the only statement of a
176 // conditional branch w/o enclosing {} braces, since the CHECK macros expand into several state-
177 // ments!
178
179 #define PENDING_EXCEPTION (((ThreadShadow*)THREAD)->pending_exception())
180 #define HAS_PENDING_EXCEPTION (((ThreadShadow*)THREAD)->has_pending_exception())
181 #define CLEAR_PENDING_EXCEPTION (((ThreadShadow*)THREAD)->clear_pending_exception())
182
183 #define CHECK THREAD); if (HAS_PENDING_EXCEPTION) return ; (0
184 #define CHECK_(result) THREAD); if (HAS_PENDING_EXCEPTION) return result; (0
185 #define CHECK_0 CHECK_(0)
186 #define CHECK_NH CHECK_(Handle())
187 #define CHECK_NULL CHECK_(NULL)
188 #define CHECK_false CHECK_(false)
189
190 // The THROW... macros should be used to throw an exception. They require a THREAD variable to be
191 // visible within the scope containing the THROW. Usually this is achieved by declaring the function
192 // with a TRAPS argument.
193
194 #define THREAD_AND_LOCATION THREAD, __FILE__, __LINE__
195
196 #define THROW_OOP(e) \
197 { Exceptions::_throw_oop(THREAD_AND_LOCATION, e); return; }
198
199 #define THROW_HANDLE(e) \
200 { Exceptions::_throw(THREAD_AND_LOCATION, e); return; }
201
202 #define THROW(name) \
203 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, NULL); return; }
204
205 #define THROW_MSG(name, message) \
206 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message); return; }
207
208 #define THROW_MSG_LOADER(name, message, loader, protection_domain) \
209 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message, loader, protection_domain); return; }
210
211 #define THROW_ARG(name, signature, args) \
212 { Exceptions::_throw_args(THREAD_AND_LOCATION, name, signature, args); return; }
213
214 #define THROW_OOP_(e, result) \
215 { Exceptions::_throw_oop(THREAD_AND_LOCATION, e); return result; }
216
217 #define THROW_HANDLE_(e, result) \
218 { Exceptions::_throw(THREAD_AND_LOCATION, e); return result; }
219
220 #define THROW_(name, result) \
221 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, NULL); return result; }
222
223 #define THROW_MSG_(name, message, result) \
224 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message); return result; }
225
226 #define THROW_MSG_LOADER_(name, message, loader, protection_domain, result) \
227 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message, loader, protection_domain); return result; }
228
229 #define THROW_ARG_(name, signature, args, result) \
230 { Exceptions::_throw_args(THREAD_AND_LOCATION, name, signature, args); return result; }
231
232 #define THROW_MSG_CAUSE_(name, message, cause, result) \
233 { Exceptions::_throw_msg_cause(THREAD_AND_LOCATION, name, message, cause); return result; }
234
235
236 #define THROW_OOP_0(e) THROW_OOP_(e, 0)
237 #define THROW_HANDLE_0(e) THROW_HANDLE_(e, 0)
238 #define THROW_0(name) THROW_(name, 0)
239 #define THROW_MSG_0(name, message) THROW_MSG_(name, message, 0)
240 #define THROW_WRAPPED_0(name, oop_to_wrap) THROW_WRAPPED_(name, oop_to_wrap, 0)
241 #define THROW_ARG_0(name, signature, arg) THROW_ARG_(name, signature, arg, 0)
242 #define THROW_MSG_CAUSE_0(name, message, cause) THROW_MSG_CAUSE_(name, message, cause, 0)
243
244 #define THROW_NULL(name) THROW_(name, NULL)
245 #define THROW_MSG_NULL(name, message) THROW_MSG_(name, message, NULL)
246
247 // The CATCH macro checks that no exception has been thrown by a function; it is used at
248 // call sites about which is statically known that the callee cannot throw an exception
249 // even though it is declared with TRAPS.
250
251 #define CATCH \
252 THREAD); if (HAS_PENDING_EXCEPTION) { \
253 oop ex = PENDING_EXCEPTION; \
254 CLEAR_PENDING_EXCEPTION; \
255 ex->print(); \
256 ShouldNotReachHere(); \
257 } (0
258
259
260 // ExceptionMark is a stack-allocated helper class for local exception handling.
261 // It is used with the EXCEPTION_MARK macro.
262
263 class ExceptionMark {
264 private:
265 Thread* _thread;
266
267 public:
268 ExceptionMark(Thread*& thread);
269 ~ExceptionMark();
270 };
271
272
273
274 // Use an EXCEPTION_MARK for 'local' exceptions. EXCEPTION_MARK makes sure that no
275 // pending exception exists upon entering its scope and tests that no pending exception
276 // exists when leaving the scope.
277
278 // See also preserveException.hpp for PRESERVE_EXCEPTION_MARK macro,
279 // which preserves pre-existing exceptions and does not allow new
280 // exceptions.
281
282 #define EXCEPTION_MARK Thread* THREAD; ExceptionMark __em(THREAD);
283
284 #endif // SHARE_VM_UTILITIES_EXCEPTIONS_HPP