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);