1 /*
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   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
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  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
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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   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 // The THROW... macros should be used to throw an exception. They require a THREAD variable to be
 193 // visible within the scope containing the THROW. Usually this is achieved by declaring the function
 194 // with a TRAPS argument.
 195 
 196 #define THREAD_AND_LOCATION                      THREAD, __FILE__, __LINE__
 197 
 198 #define THROW_OOP(e)                                \
 199   { Exceptions::_throw_oop(THREAD_AND_LOCATION, e);                             return;  }
 200 
 201 #define THROW_HANDLE(e)                                \
 202   { Exceptions::_throw(THREAD_AND_LOCATION, e);                             return;  }
 203 
 204 #define THROW(name)                                 \
 205   { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, NULL); return;  }
 206 
 207 #define THROW_MSG(name, message)                    \
 208   { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message); return;  }
 209 
 210 #define THROW_MSG_LOADER(name, message, loader, protection_domain) \
 211   { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message, loader, protection_domain); return;  }
 212 
 213 #define THROW_ARG(name, signature, args) \
 214   { Exceptions::_throw_args(THREAD_AND_LOCATION, name, signature, args);   return; }
 215 
 216 #define THROW_OOP_(e, result)                       \
 217   { Exceptions::_throw_oop(THREAD_AND_LOCATION, e);                           return result; }
 218 
 219 #define THROW_HANDLE_(e, result)                       \
 220   { Exceptions::_throw(THREAD_AND_LOCATION, e);                           return result; }
 221 
 222 #define THROW_(name, result)                        \
 223   { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, NULL); return result; }
 224 
 225 #define THROW_MSG_(name, message, result)           \
 226   { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message); return result; }
 227 
 228 #define THROW_MSG_LOADER_(name, message, loader, protection_domain, result) \
 229   { Exceptions::_throw_msg(THREAD_AND_LOCATION, name, message, loader, protection_domain); return result; }
 230 
 231 #define THROW_ARG_(name, signature, args, result) \
 232   { Exceptions::_throw_args(THREAD_AND_LOCATION, name, signature, args); return result; }
 233 
 234 #define THROW_MSG_CAUSE_(name, message, cause, result)   \
 235   { Exceptions::_throw_msg_cause(THREAD_AND_LOCATION, name, message, cause); return result; }
 236 
 237 
 238 #define THROW_OOP_0(e)                      THROW_OOP_(e, 0)
 239 #define THROW_HANDLE_0(e)                   THROW_HANDLE_(e, 0)
 240 #define THROW_0(name)                       THROW_(name, 0)
 241 #define THROW_MSG_0(name, message)          THROW_MSG_(name, message, 0)
 242 #define THROW_WRAPPED_0(name, oop_to_wrap)  THROW_WRAPPED_(name, oop_to_wrap, 0)
 243 #define THROW_ARG_0(name, signature, arg)   THROW_ARG_(name, signature, arg, 0)
 244 #define THROW_MSG_CAUSE_0(name, message, cause) THROW_MSG_CAUSE_(name, message, cause, 0)
 245 
 246 #define THROW_NULL(name)                    THROW_(name, NULL)
 247 #define THROW_MSG_NULL(name, message)       THROW_MSG_(name, message, NULL)
 248 
 249 // The CATCH macro checks that no exception has been thrown by a function; it is used at
 250 // call sites about which is statically known that the callee cannot throw an exception
 251 // even though it is declared with TRAPS.
 252 
 253 #define CATCH                              \
 254   THREAD); if (HAS_PENDING_EXCEPTION) {    \
 255     oop ex = PENDING_EXCEPTION;            \
 256     CLEAR_PENDING_EXCEPTION;               \
 257     ex->print();                           \
 258     ShouldNotReachHere();                  \
 259   } (0
 260 
 261 
 262 // ExceptionMark is a stack-allocated helper class for local exception handling.
 263 // It is used with the EXCEPTION_MARK macro.
 264 
 265 class ExceptionMark {
 266  private:
 267   Thread* _thread;
 268 
 269  public:
 270   ExceptionMark(Thread*& thread);
 271   ~ExceptionMark();
 272 };
 273 
 274 
 275 
 276 // Use an EXCEPTION_MARK for 'local' exceptions. EXCEPTION_MARK makes sure that no
 277 // pending exception exists upon entering its scope and tests that no pending exception
 278 // exists when leaving the scope.
 279 
 280 // See also preserveException.hpp for PRESERVE_EXCEPTION_MARK macro,
 281 // which preserves pre-existing exceptions and does not allow new
 282 // exceptions.
 283 
 284 #define EXCEPTION_MARK                           Thread* THREAD; ExceptionMark __em(THREAD);
 285 
 286 #endif // SHARE_VM_UTILITIES_EXCEPTIONS_HPP