1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   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.
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   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  *
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
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  20  * or visit www.oracle.com if you need additional information or have any
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  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