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 friend class VMStructs;
62
63 protected:
64 oop _pending_exception; // Thread has gc actions.
65 const char* _exception_file; // file information for exception (debugging only)
66 int _exception_line; // line information for exception (debugging only)
67 friend void check_ThreadShadow(); // checks _pending_exception offset
68
69 // The following virtual exists only to force creation of a vtable.
70 // We need ThreadShadow to have a vtable, even in product builds,
71 // so that its layout will start at an offset of zero relative to Thread.
72 // Some C++ compilers are so "clever" that they put the ThreadShadow
73 // base class at offset 4 in Thread (after Thread's vtable), if they
74 // notice that Thread has a vtable but ThreadShadow does not.
75 virtual void unused_initial_virtual() { }
76
77 public:
78 oop pending_exception() const { return _pending_exception; }
79 bool has_pending_exception() const { return _pending_exception != NULL; }
80 const char* exception_file() const { return _exception_file; }
81 int exception_line() const { return _exception_line; }
82
83 // Code generation support
84 static ByteSize pending_exception_offset() { return byte_offset_of(ThreadShadow, _pending_exception); }
85
86 // use THROW whenever possible!
87 void set_pending_exception(oop exception, const char* file, int line);
88
89 // use CLEAR_PENDING_EXCEPTION whenever possible!
90 void clear_pending_exception();
91
92 ThreadShadow() : _pending_exception(NULL),
93 _exception_file(NULL), _exception_line(0) {}
94 };
95
96
97 // Exceptions is a helper class that encapsulates all operations
98 // that require access to the thread interface and which are
99 // relatively rare. The Exceptions operations should only be
100 // used directly if the macros below are insufficient.
101
102 class Exceptions {
103 static bool special_exception(Thread *thread, const char* file, int line, Handle exception);
104 static bool special_exception(Thread* thread, const char* file, int line, Symbol* name, const char* message);
105 public:
106 // this enum is defined to indicate whether it is safe to
107 // ignore the encoding scheme of the original message string.
108 typedef enum {
109 safe_to_utf8 = 0,
110 unsafe_to_utf8 = 1
111 } ExceptionMsgToUtf8Mode;
112 // Throw exceptions: w/o message, w/ message & with formatted message.
113 static void _throw_oop(Thread* thread, const char* file, int line, oop exception);
114 static void _throw(Thread* thread, const char* file, int line, Handle exception, const char* msg = NULL);
115 static void _throw_msg(Thread* thread, const char* file, int line,
116 Symbol* name, const char* message, Handle loader,
117 Handle protection_domain);
118 static void _throw_msg(Thread* thread, const char* file, int line,
119 Symbol* name, const char* message);
120 static void _throw_args(Thread* thread, const char* file, int line,
121 Symbol* name, Symbol* signature,
122 JavaCallArguments* args);
123 static void _throw_msg_cause(Thread* thread, const char* file,
124 int line, Symbol* h_name, const char* message,
125 Handle h_cause, Handle h_loader, Handle h_protection_domain);
126 static void _throw_msg_cause(Thread* thread, const char* file, int line,
127 Symbol* name, const char* message, Handle cause);
128
129 // There is no THROW... macro for this method. Caller should remember
130 // to do a return after calling it.
131 static void fthrow(Thread* thread, const char* file, int line, Symbol* name,
132 const char* format, ...);
133
134 // Create and initialize a new exception
135 static Handle new_exception(Thread* thread, Symbol* name,
136 Symbol* signature, JavaCallArguments* args,
137 Handle cause, Handle loader,
138 Handle protection_domain);
139
140 static Handle new_exception(Thread* thread, Symbol* name,
141 const char* message, Handle cause, Handle loader,
142 Handle protection_domain,
143 ExceptionMsgToUtf8Mode to_utf8_safe = safe_to_utf8);
144
145 static Handle new_exception(Thread* thread, Symbol* name,
146 const char* message,
147 ExceptionMsgToUtf8Mode to_utf8_safe = safe_to_utf8);
148
149 static void throw_stack_overflow_exception(Thread* thread, const char* file, int line, methodHandle method);
150
151 // for AbortVMOnException flag
152 NOT_PRODUCT(static void debug_check_abort(Handle exception, const char* message = NULL);)
153 NOT_PRODUCT(static void debug_check_abort(const char *value_string, const char* message = NULL);)
154 };
155
156
157 // The THREAD & TRAPS macros facilitate the declaration of functions that throw exceptions.
158 // Convention: Use the TRAPS macro as the last argument of such a function; e.g.:
159 //
160 // int this_function_may_trap(int x, float y, TRAPS)
161
162 #define THREAD __the_thread__
163 #define TRAPS Thread* THREAD
164
165
166 // The CHECK... macros should be used to pass along a THREAD reference and to check for pending
167 // exceptions. In special situations it is necessary to handle pending exceptions explicitly,
168 // in these cases the PENDING_EXCEPTION helper macros should be used.
169 //
170 // Macro naming conventions: Macros that end with _ require a result value to be returned. They
171 // are for functions with non-void result type. The result value is usually ignored because of
172 // the exception and is only needed for syntactic correctness. The _0 ending is a shortcut for
173 // _(0) since this is a frequent case. Example:
174 //
175 // int result = this_function_may_trap(x_arg, y_arg, CHECK_0);
176 //
177 // CAUTION: make sure that the function call using a CHECK macro is not the only statement of a
178 // conditional branch w/o enclosing {} braces, since the CHECK macros expand into several state-
179 // ments!
180
181 #define PENDING_EXCEPTION (((ThreadShadow*)THREAD)->pending_exception())
182 #define HAS_PENDING_EXCEPTION (((ThreadShadow*)THREAD)->has_pending_exception())
183 #define CLEAR_PENDING_EXCEPTION (((ThreadShadow*)THREAD)->clear_pending_exception())
184
185 #define CHECK THREAD); if (HAS_PENDING_EXCEPTION) return ; (0
186 #define CHECK_(result) THREAD); if (HAS_PENDING_EXCEPTION) return result; (0
187 #define CHECK_0 CHECK_(0)
188 #define CHECK_NH CHECK_(Handle())
189 #define CHECK_NULL CHECK_(NULL)
190 #define CHECK_false CHECK_(false)
191
192 #define CHECK_AND_CLEAR THREAD); if (HAS_PENDING_EXCEPTION) { CLEAR_PENDING_EXCEPTION; return; } (0
193 #define CHECK_AND_CLEAR_(result) THREAD); if (HAS_PENDING_EXCEPTION) { CLEAR_PENDING_EXCEPTION; return result; } (0
194 #define CHECK_AND_CLEAR_0 CHECK_AND_CLEAR_(0)
195 #define CHECK_AND_CLEAR_NH CHECK_AND_CLEAR_(Handle())
196 #define CHECK_AND_CLEAR_NULL CHECK_AND_CLEAR_(NULL)
197 #define CHECK_AND_CLEAR_false CHECK_AND_CLEAR_(false)
198
199 // The THROW... macros should be used to throw an exception. They require a THREAD variable to be
200 // visible within the scope containing the THROW. Usually this is achieved by declaring the function
201 // with a TRAPS argument.
202
203 #define THREAD_AND_LOCATION THREAD, __FILE__, __LINE__
204
205 #define THROW_OOP(e) \
206 { Exceptions::_throw_oop(THREAD_AND_LOCATION, e); return; }
207
208 #define THROW_HANDLE(e) \
209 { Exceptions::_throw(THREAD_AND_LOCATION, e); return; }
210
211 #define THROW(name) \
212 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, NULL); return; }
213
214 #define THROW_MSG(name, message) \
215 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message); return; }
216
217 #define THROW_MSG_LOADER(name, message, loader, protection_domain) \
218 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message, loader, protection_domain); return; }
219
220 #define THROW_ARG(name, signature, args) \
221 { Exceptions::_throw_args(THREAD_AND_LOCATION, name, signature, args); return; }
222
223 #define THROW_OOP_(e, result) \
224 { Exceptions::_throw_oop(THREAD_AND_LOCATION, e); return result; }
225
226 #define THROW_HANDLE_(e, result) \
227 { Exceptions::_throw(THREAD_AND_LOCATION, e); return result; }
228
229 #define THROW_(name, result) \
230 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, NULL); return result; }
231
232 #define THROW_MSG_(name, message, result) \
233 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message); return result; }
234
235 #define THROW_MSG_LOADER_(name, message, loader, protection_domain, result) \
236 { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message, loader, protection_domain); return result; }
237
238 #define THROW_ARG_(name, signature, args, result) \
239 { Exceptions::_throw_args(THREAD_AND_LOCATION, name, signature, args); return result; }
240
241 #define THROW_MSG_CAUSE_(name, message, cause, result) \
242 { Exceptions::_throw_msg_cause(THREAD_AND_LOCATION, name, message, cause); return result; }
243
244
245 #define THROW_OOP_0(e) THROW_OOP_(e, 0)
246 #define THROW_HANDLE_0(e) THROW_HANDLE_(e, 0)
247 #define THROW_0(name) THROW_(name, 0)
248 #define THROW_MSG_0(name, message) THROW_MSG_(name, message, 0)
249 #define THROW_WRAPPED_0(name, oop_to_wrap) THROW_WRAPPED_(name, oop_to_wrap, 0)
250 #define THROW_ARG_0(name, signature, arg) THROW_ARG_(name, signature, arg, 0)
251 #define THROW_MSG_CAUSE_0(name, message, cause) THROW_MSG_CAUSE_(name, message, cause, 0)
252
253 #define THROW_NULL(name) THROW_(name, NULL)
254 #define THROW_MSG_NULL(name, message) THROW_MSG_(name, message, NULL)
255
256 // The CATCH macro checks that no exception has been thrown by a function; it is used at
257 // call sites about which is statically known that the callee cannot throw an exception
258 // even though it is declared with TRAPS.
259
260 #define CATCH \
261 THREAD); if (HAS_PENDING_EXCEPTION) { \
262 oop ex = PENDING_EXCEPTION; \
263 CLEAR_PENDING_EXCEPTION; \
264 ex->print(); \
265 ShouldNotReachHere(); \
266 } (0
267
268 // ExceptionMark is a stack-allocated helper class for local exception handling.
269 // It is used with the EXCEPTION_MARK macro.
270
271 class ExceptionMark {
272 private:
273 Thread* _thread;
274
275 public:
276 ExceptionMark(Thread*& thread);
277 ~ExceptionMark();
278 };
279
280
281
282 // Use an EXCEPTION_MARK for 'local' exceptions. EXCEPTION_MARK makes sure that no
283 // pending exception exists upon entering its scope and tests that no pending exception
284 // exists when leaving the scope.
285
286 // See also preserveException.hpp for PRESERVE_EXCEPTION_MARK macro,
287 // which preserves pre-existing exceptions and does not allow new
288 // exceptions.
289
290 #define EXCEPTION_MARK Thread* THREAD; ExceptionMark __em(THREAD);
291
292 #endif // SHARE_VM_UTILITIES_EXCEPTIONS_HPP